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Efik Origin Story Compiled by David Baker, adapted by Newsela In this origin story of the
Nigerian Efik people, the first
humans defy the gods to
achieve greater power and
wisdom. The Efik people live in southern Nigeria, for many centuries dwelling near the
regions around the Cross River. They traditionally worshipped the god Abassi
as a supreme creator. Their belief system was very relaxed. They had no formal
priesthood or organized religious institutions. Worship and ritual were carried
out on an individual or family level. Their creation story is a tale of humans
defying the gods in order to achieve greater power and wisdom. Before Abassi there was nothing. Abassi was god of the Universe, and
giver of life, death, and justice. He was so powerful that he could create
life, heal the sick, and even raise the dead. Some say that Abassi was
the Sun, and they worshipped it as it rose and set every day. Abassi lived
in the sky with his wife, Atai. She was a wise goddess, who often gave
Abassi good advice. Abassi created the stars, the Earth, and all the wildlife upon it. He also
created two humans, a man and a woman. These humans lived with
Abassi and Atai in the sky. They were very innocent and had little knowledge. Abassi and Atai looked after them, protected them, and even fed
them, because they did not know how to feed themselves. One day, the
humans were looking down from the sky at the Earth. They decided they
wanted to live there. But when they asked Abassi if they could leave
the sky and live on the Earth, he forbade it. The Earth was a place with
many secrets where many things could be learned. Abassi feared that
the humans would one day match his wisdom, or even surpass it. Atai proposed a compromise. The humans could go live on Earth, but they
had to return to the sky every day to have their meals. The humans were
forbidden to learn to hunt or farm. They were also forbidden to marry
and have children, because a large nation of people might one day challenge
the power of Abassi. For a while, this plan worked. The humans returned to the sky every day
to take their meals. However, one day, the woman decided she was sick
of being fed like a helpless child. She went out into the fields and began to
farm. When the time came for dinner, she defiantly refused to return to
the sky with the man. The next day, the man visited the woman in the fields and saw she was
growing her own food. He decided to help her. Before long, the man and
woman fell in love. They did not return to the sky again. Many years went
by and they had many children. When those children were old enough,
they joined their parents working in the field. They all continued to learn
the secrets of the Earth and teach them to each other. The humans tried to hide their children from the sight of Abassi, but the
god saw them. He grew very angry. He blamed his wife, Atai, because
she had convinced him to let the humans live on Earth. Abassi feared that
one day, the humans would have learned so much that they would surpass his wisdom. He also feared they would grow so numerous that they
would surpass his power But Atai had a plan. In order to prevent the humans from growing too
powerful, she sent evil into the world in the form of death and discord. The
evil was so strong that the man and woman immediately died. Their
children have suffered the ills of the world and argued among themselves
ever since. But because their mother defied the gods, the humans have
continued to learn the secrets of the Earth. For Further Discussion Now that you’ve read all of the origin stories, see how your Origin Stories Chart answers compare to those on the answer key. Did we miss anything? If so, share what we missed in the Answers Area below. Sources Beier, Ulli. The Origin of Life and Death: African Creation Myths.
London: Heinemann, 1966. Hackett, Rosalind. Religion in Calabar: The Religious Life and History
of a Nigerian Town. Berlin: Mouton de Gruyter, 1988. Leeming, David Adams. Creation Myths of the World: An Encyclopedia.
2nd ed. Santa Barbara: ABC-CLIO, 2010. Lynch, Patricia Ann, and Jeremy Roberts. African Mythology: A to Z.
2nd ed. New York: Chelsea House, 2010. Image Credits Landscape with Stars by Henri-Edmond Cross
© Corbis |
What Happened on Easter Island? By David Burzillo, adapted by Newsela Easter Island is most famous for moai,
the huge statues that encircle the island.
What caused its civilization to collapse? Introduction In the spring of 1722, Dutch explorers landed on Easter Island. Upon arrival, they found
a most puzzling and fascinating sight – hundreds of massive stone statues were all
over this tiny island. What are they? What do they mean? Why are they placed where
they are? How did they get there? The huge stone figures of Easter Island have fascinated explorers, researchers, and
just about anyone who has seen them for hundreds of years. In spite of many years of
research, scholars still don’t agree on the answers to the puzzle of the statues. Even
more intriguing, perhaps, are the questions surrounding the rise and fall of the
population that built them. Easter Island, which native Polynesians call Rapa Nui, is located in the eastern Pacific
Ocean. Today it is part of Chile, where it is called Isla de Pascua. The island is more
than 2,000 miles from nearly all its neighbors. Easter Island is 700,000 years old, which is fairly young for an island. It was formed
by volcanic activity, and now its landscape is dominated by three dormant volcanoes.
The island is very small—around 60 square miles. This makes it less than one tenth
the size the Hawaiian island of Maui, or just about the size of Gainesville, Florida. Location of Easter Island in the southeastern Pacific Ocean Scholars do not agree on when people first settled on Easter Island. The first arrived
by boat sometime between 300 and 800 CE. These settlers probably rowed there from
a Polynesian island about 4,000 miles away. They brought bananas, taro, sugarcane,
chickens, and rats with them, adding to the natural life already on the island. Today,
Easter Island is home to over 7,600 people1^11start superscript, 1, end superscript and attracts over 100,000 tourists a year2^22squared. Why is Easter Island so fascinating? For such a small piece of land, Easter Island has been given a lot of attention for a
long time. One source of this interest is the beauty of the island and its potential for
supporting life. The Dutch ship captain Jacob Roggeveen wrote the following
description of the island in 1722: Nor can the aforementioned land be termed sandy, because we found it not only not
sandy but on the contrary exceedingly fruitful, producing bananas, potatoes, sugarcane
of remarkable thickness, and many other kinds of the fruits of the earth;
although destitute of [lacking] large trees and domestic animals, except poultry. This
place, as far as its rich soil and good climate are concerned, is such that it might be
made into an earthly Paradise…..3^33cubed Satellite image of Easter Island, Earth Observatory, NASA, public domain. But by far, Easter Island is most famous for
the moai. The moai (pronounced moe-eye or
mah-eye) are huge statues that encircle
the island. Moai at Rano Raraku, Easter Island, by Aurbina,
Public Domain. These enormous statues of elongated faces
are so popular there is even a moai emoji.
There are between 887 and 1,000 moai on
Easter Island. The largest are 33 feet high and
weigh as much as 80 tons. Most of them are
located miles from the quarries that provided
the stone for them. The size, number, and
location of the moai raise a number of
questions that scholars have puzzled over for
many years. How did the people carve these
statues without metal tools? How did they
move them without the help of large animals?
What purpose did they serve for the islanders? Detailed topographic map in Spanish of Easter island, by Eric Gaba, translation Osmar Valdebenito, CC BY-SA 2.5 Anthropologists, archaeologists, and historians have been digging for clues about this
fascinating place for many years, but there are no simple answers. Terry Hunt and Carl
Lipo, both experts in anthropology and archaeology, took on these tough questions. In
2011, they published an article that re-created how the Easter Islanders may have been
able to move the statues. Then, in January 2019, a research team including Hunt and
Lipo published another article explaining the location of the statues. They suggested
that the moai may have been placed in areas where fresh or brackish water was found,
as a way of marking the location of this important resource.4^44start superscript, 4, end superscript Exciting answers (or at least theories) are still being published, and the many
questions about Easter Island will probably continue to inspire research across many
disciplines. In recent years, researchers have also begun to ask questions about the
history of environmental change and population decline on the island. These changes
are represented in the following two charts. What were the causes of the changes represented in these graphs? How could such
changes have happened to an island with such an isolated but advanced society? As they’ve explored these questions, historians, archaeologists, and botanists have
uncovered evidence. Some of this evidence is in the form of written documents. Some
is in the form of artifacts and other material remains. Historians have studied the
accounts of the first European visitors to the island. These impressions that people wrote when they first came ashore to this new and intriguing place provide
information about what the island was like hundreds of years ago. Archaeologists
have uncovered artifacts and excavated the remains of buildings from ancient
settlements. A variety of scientists have studied the plants, animals, and geology of the
island. Easter Islanders did have a form of writing, called rongorongo, but scholars
have not yet discovered a way to read this writing. Easter Islanders may have written
about the challenges they faced, but we may never know what they thought. How have scholars explained the environmental and population changes on Easter Island? Some scholars place the blame for changes on the island on humans. Geographer
Jared Diamond illustrates this somewhat controversial opinion: In short, the reason for Easter’s unusually severe degree of deforestation isn’t that
those seemingly nice people really were unusually bad or improvident [careless].
Instead, they had the misfortune to be living in one of the most fragile environments,
at the highest risk for deforestation, of any Pacific people…. Easter’s isolation makes
it the clearest example of a society that destroyed itself by overexploiting [overusing]
its own resources.5^55start superscript, 5, end superscript Many of the explanations that blame humans for these problems have focused on the
issue of the overuse of the resources available on Easter Island. Deforestation
(removal of trees) is the primary cause in these explanations. Easter Islanders cut
down trees for a variety of purposes. Trees were probably used to move the moai.
Trees also provided the materials for making rope. People also used trees for fuel.
Terry Hunt, the anthropologist/archaeologist mentioned earlier, has found that
“Between 1300 and 1650…inhabitants burned wood from trees, but they used grass,
ferns and other similar plants for fuel after that point.”6^66start superscript, 6, end superscript This tells us that deforestation
was underway by the time Europeans arrived. Some researchers argue that trees were cut down using a method known as “slash
and burn” to create more farmland. One research team found “a single layer of
charcoal and ashes several millimeters in thickness can be found deep below the
recent surface…. The extensive distribution of charcoal layers can only have one
explanation: widespread fires in the woodland of Rapa Nui…. the beginning of intensive
slash and burn….”7^77start superscript, 7, end superscript Other experts have focused more on the role of environmental factors in the changes
on Easter Island. Some of these researchers, including Hunt and Lipo, have focused on the island’s large rat population. Rats did not have many competitors and their
population could grow rapidly. Rats were big consumers of palm nuts, the seeds for
growing trees on Easter Island. Hunt and Lipo write, “It takes several years for the tree
to form a trunk and sixty or more years to produce seeds. With rats consuming so
many of the palm nuts, as the record suggests, few trees could regrow naturally.”8^88start superscript, 8, end superscript Many researchers have focused on the impact of diseases brought by European
visitors to the island. Because Easter Island is so remote, it had very little contact with
other human communities for hundreds of years. The people there developed no
immunity to the diseases brought by Europeans. As a result, sickness would have
spread quickly. Hunt and Lipo point out that the Europeans were probably unaware of the enormous
effect disease would have had on the island’s population. They write that Captain Cook
and his men, who visited the island around 1770, “were perplexed by the small
population size, what they perceived as poverty, and generally the disheveled [messy]
state of things; in hindsight, this is precisely what the aftermath of an epidemic and
population crash would look like.”9^99start superscript, 9, end superscript Conclusion Scholars from many disciplines continue to study Easter Island in an attempt to
understand how it changed over the centuries, and in particular how humans were
affected by or caused these changes. The moai are a stunning visual reminder of the
deeper mysteries that surround the island and its inhabitants. Perhaps those statues
are the perfect guarantee that scholars will continue trying to understand how and
why the population of this remote corner of the world developed as it did. All 15 standing moai at Ahu Tongariki, excavated and restored in the 1990s, by Bjørn Christian Tørrissen,
CC BY-SA 3.0. [Notes] [Sources and attributions] |
Big History: An Overview By John Green, adapted by Newsela History is an attempt to understand both our
insignificance and our significance. To study history is
to better understand the world and your place in it. You are very small. You are one of several billion living members of your species, a
species that lives on the fifth largest planet orbiting a star we call the Sun. There are
more than a hundred billion such stars in our galaxy, and perhaps a hundred billion
galaxies in the Universe. It’s almost impossible to grasp your smallness—there are
more stars in the Universe than there are grains of sand on Earth. And yet, you’re also very large. You’re a member of an extraordinarily powerful
species that has dramatically reshaped the biosphere, the first species on Earth to
understand the vastness of the Universe around it. Your choices—how to organize
your community, what to value, what to battle against—shape not just your life but the
lives of those around you and the lives of those still to come. And you are physically
vast as well: Your body contains trillions of cells, and is colonized by trillions more
microscopic organisms. What Is History? History is an attempt to understand both our insignificance and our significance. To
study history is to better understand the world and your place in it. You, and the other
humans with whom you share this world, are the culmination of the human story. What Is Big History? There’s a lot more to history than the human story. Let’s consider the world before
humans. If you think of history as the story of life on Earth, almost all of it played out
before our species (Homo sapiens) showed up on the scene. After all, we’ve been around
only for the last 250,000 or so years—less than 0.01% of the history of life on Earth. From the very beginning, we’ve had different stories that explain the origins of the
Universe, our planet Earth, and life itself. These origin stories, as they’re called, are as
varied as the cultures that created them. At its heart, Big History is simply another
origin story. However, it differs from all other origin stories because it’s science based. Big History uses the information we have available—the scientific evidence—to
create an understanding of the Universe. Thresholds of Increasing Complexity Because the scale of Big History is so vast (remember, it covers the history of the Universe), it would be impossible for this story to include everything. All historians have to make choices about what to include and what to leave out in the stories they tell. So, what does the story of Big History focus on? Big Historians focus on eight turning points in the history of the Universe, which we call thresholds. These are moments when the Universe became significantly more complex than it had been previously. Threshold 1: The Big Bang Modern science suggests that the Universe was created in a “big bang” about 13.8
billion years ago. The Big Bang was a split second in which all matter and energy expanded at tremendous
speed and became the Universe. What was there before the Big Bang? It’s mind-bending
to think about, but in some ways, there was no “before” the Big Bang, because the Big
Bang created not only space as we know it, but also time as we know it. The important
thing to know is that around 13.8 billion years ago, very suddenly, the Universe exploded
into being. It’s also important to recognize that although scientists know a lot about the
Big Bang, there are still many questions about the details that are being researched. Threshold 2: The Stars Light Up After the Big Bang, the Universe expanded and cooled. It took some time (about
380,000 years), but eventually it was cool enough for the simplest atoms, hydrogen
and helium, to form. The early Universe consisted almost entirely of hydrogen and
helium for a very long time. After a few hundred million years, clouds of hydrogen and
helium began to collapse, and the increasing heat and pressure generated by collapse
led to the creation of the first stars. Stars represent the second threshold of increasing
complexity in Big History. Not only are stars more complex than simple atoms, they’re
also able to create tremendous energy. Over time, gravity grouped stars into galaxies,
which created further complexity in the Universe. Threshold 3: New Chemical Elements Stars made the Universe more complex, but the Universe still consisted primarily of
hydrogen and helium. This changed when the first generation of stars died. The death
of a star can generate high temperatures and pressures like those in the Big Bang, and
this makes possible the creation of more complex atoms. A greater variety of atoms is
critical to making more complex things like planets and living things, so the death of
stars is the third threshold of increasing complexity in Big History. Threshold 4: Earth and the Solar System Our Sun is a star, and like all other stars, it was formed from the collapse of a huge
cloud of gas and dust particles. More than 99 percent of this material went to make up
the Sun, but wisps of matter orbited around it at various distances. Over time, the matter
in each orbit was drawn together by gravity. The gravitational pull created violent
collisions into lumps of matter that eventually formed the planets. This process, which
we call accretion, is how our Earth was formed approximately 4.5 billion years ago. Threshold 5: Life Around volcanic vents at the bottom of Earth’s oceans, complex chemicals engaged in
ever-changing reactions powered by the heat from these volcanoes. Those reactions
led to the formation of complex chemicals that eventually created the first living
organisms. The earliest living organisms consisted of single cells, as most living
organisms do even today. Like all living organisms, those early single-celled creatures
were subject to the laws of evolution. Generation by generation, the average features
of species gradually changed, eventually forming entirely new species. And for a very long time, that was it: single-celled, microscopic organisms. Life first
emerged on Earth perhaps three billion years ago; the first multicellular life didn’t show
up until around one billion years ago. But slowly, life grew more and more complex, and
large, multi-cellular organisms eventually spread, not only in water, but also on land. One hundred million years ago, the land-based animals that flourished most were the
reptiles we call dinosaurs. About 65 million years ago, however, most of them died off. Now other types of large animals could flourish in their place. Most successful of all in
the last 65 million years has been the large class of animals called mammals. Threshold 6: Collective Learning The extinction of the dinosaurs allowed mammals and primates to evolve and
eventually dominate the Earth. Our ancestors, the hominins, are primates, and they first appeared between five and
seven million years ago in Africa. Over millions of years, hominins evolved in
important ways, both physically and socially. About 200,000 years ago, Homo sapiens,
which means “wise human,” appeared. Modern humans developed language, a method
of communication that allows them to share complex ideas and pass on knowledge
from generation to generation. This process is known as collective learning. In other
species, knowledge dies with the generation that created it. Humans have the ability to
build on the accomplishments of previous generations. Threshold 7: Agriculture Our ancestors lived by foraging. Foragers survive by gathering plants, hunting animals,
and scavenging the remains of animals killed by other predators. Foraging supported
early humans for millions of years. About 12,000 years ago, humans began to
domesticate plants and animals, in other words, to farm. They began interfering with
the natural life cycles of plants and animals in order to control where they grew and
promote characteristics in those plants and animals they preferred. Growing food gave humans access to a vast amount of energy created by the Sun through photosynthesis.
Because foraging for survival was no longer necessary, tremendous lifestyle changes
were possible, like settling down to live in cities, creating political structures, and
developing skill and trade specializations. The results of all of these changes define
the agrarian civilizations. Farming has had a tremendous impact on the way humans
live and how they interact with the Earth. Threshold 8: Modern Revolution The adoption of farming led to dramatic changes in the way humans lived. Innovation
accelerated dramatically with the Modern Revolution, which began about 300 years
ago. Rapid growth of human population and the creation of a highly interconnected
world are some of the key features of the modern world. These features make the
modern world the eighth and final of Big History’s thresholds. What's Next? The story of the Universe isn’t only about the past. We know that this story doesn’t end
with Threshold 8. So, what’s next? What might the next threshold of increasing
complexity be? When you reach the end of this course, you’ll get to use your
knowledge of the past to speculate about the future. Because Big History isn’t just
about knowing what happened when. Big Historians look across the thresholds to
understand the connections between past and present. With that understanding,
developing a view of what the future might hold becomes more than a random
guessing game. It becomes a way of expressing your own point of view about how the
future will be the logical outcome of billions of years of the past. But let’s not get ahead of ourselves. Let’s really dig into the vastness of what got us
here. Remember, you are very small, yet very large. In any other story, this might
seem like a contradiction—but not here, not in the Big History story! |
Zulu Origin Story Compiled by David Baker, adapted by Newsela Different versions of the
Zulu origin story all share
this theme: Life has a
single common ancestor. The Zulu are a proud African people, famous throughout history for their fierceness and bravery in fending off invaders. Archaeologists tell us they traveled
to the lush green lands of south-eastern Africa many centuries ago from the
huge lake regions to the north. Their creation story has many versions, passed
down by word of mouth from generation to generation. It tells of how the
ancestors of all plants, animals, and humanity began from a single source At first, there was nothing but darkness. Earth was a lifeless rock.
But in that darkness dwelt a god, Umvelinqangi, whose voice was like
thunder and who, when angered, would shake the world with earthquakes. Umvelinqangi created a single tiny seed. He sent it to the
Earth. This seed was the very first life, from which all other life descended. It landed in the soil and sprouted into a long reed. The reed
dropped more seeds, which fell off and grew into even more reeds.
This continued until they covered a massive swamp to the north, the
land called Uthlanga. At the end of one reed, there grew a man. His name was Unkulunkulu,
known as “the first ancestor” and “the Great One.” Very small at first,
he grew so large and heavy that he snapped off the end of the reed.
Walking across the land of Uthlanga, he noticed men and women were
sprouting at the ends of the other reeds. He picked them from the reeds.
These people were the first humans, the ancestors of all nations, and
they spread across the Earth. It was from Uthlanga that the ancestors
of the Zulu journeyed south to the fertile lands they inhabit today. The Great One continued to walk among the reeds. He saw many
forms of life growing at the end of them. He gathered the fish and flung
them into the rivers. Fields and forests began to grow, so he harvested
birds and antelope, and they darted off into the wild. He picked cattle
so they could be used by humans. He plucked off a ball of fire and a
round glowing stone, and flung them into the sky. These were the Sun
and Moon. Light came into the world. The Great One also plucked from the reeds fierce lions and other
beasts that would travel the lands hunting prey. He harvested magical
creatures, some good and some bad. One was the snake-like goddess
of the rivers, Mamlambo, rumored by some Zulu to drown people, eat
their faces, and suck out their brains. Another goddess was Mbaba
Mwana Waresa, a beautiful woman who created rain and rainbows, and
who invented farming and gave the Zulu the gift of beer. One of the final acts of the Great One was the most tragic. He plucked
the first chameleon off a reed and sent it to give humans the following
message: “Men must not die.” By the words of the Great One, humans
would become immortal. Unfortunately, the chameleon was slow and
lazy in his journey. The Great One grew impatient and picked a different
lizard from a reed. This lizard was fast and quickly arrived to give word to the humans.
But the lizard did not bear the same instructions. Instead the lizard
uttered the words, “Men must die.” And so from that day, humans
became mortal. It is said that chameleons change color because they
are so ashamed their ancestor was not fast enough to spare humankind the invention of death. Sources Leeming, David Adams. Creation Myths of the World: An Encyclopedia.
2nd ed. Santa Barbara: ABC-CLIO, 2010. Lynch, Patricia Ann, and Jeremy Roberts. African Mythology: A to Z.
2nd ed. New York: Chelsea House, 2010. Image Credits Zulu Huts on Film Set KwaZulu Natal, South Africa
© Corbis |
All of the following terms appear in this unit. The terms are arranged here in alphabetical order. adapt — Make fit for, or change to suit a new purpose; adapt or conform oneself to new or different conditions ancestor — Someone from whom you are descended (but usually more remote than a grandparent) astrophysics — The study of the properties and interactions of planets, stars, galaxies, and other astronomical objects. Big Bang — A theory, first articulated in the 1920s, proposing that the Universe started out extremely hot and dense and gradually cooled off as it expanded. Big History — A unified account of the entire history of the Universe that uses evidence and ideas from many disciplines to create a broad context for understanding humanity; a modern scientific origin story. century — A period of 100 years challenge — Issue a challenge to; a demanding or stimulating situation; a call to engage in a contest or fight; questioning a statement and demanding an explanation complexity — A quality of an object or system that has diverse components precisely arranged in connection with one another (so that new properties emerge which did not exist in the components alone). cosmology — The study of the Universe on its largest scales, including its origin. creation — The even that occurred at the beginning of something; the act of starting something for the first time; the human act of creating; (theology) God's act of bringing the Universe into existence; everything that exists anywhere creature — A living organism characterized by voluntary movement; emergent properties — Properties of a complex system that are not present within its parts but that emerge only when those parts are combined. entropy (the law of) — The natural tendency of all things to move from order to disorder. (Note: Although often called the law of entropy, it is more accurate to refer to it as the second law of thermodynamics.) goddess — A female deity Goldilocks Conditions — Specific set of conditions necessary to enable greater complexity. The reference is to the fairy tale Goldilocks and the Three Bears, in which Goldilocks looks for the porridge, chair, and bed that are “just right.” history — The study of past events. human — Relating to a person; having human form or attributes as opposed to those of animals or divine beings; any living or extinct member of the family Hominidae characterized by superior intelligence, articulate speech, and erect carriage; characteristic of humanity ingredients — Components that are put together to form something new and more complex. interdisciplinary approach — An approach to a subject that uses the viewpoints of many different kinds of scholars about the same topic. For instance, Big History relies on information from cosmologists, astrophysicists, geologists, chemists, paleontologists, biologists, anthropologists, and historians, as well as experts in other disciplines, to learn about the past. origin story — A narrative about the beginning of the Universe and humanity. religion — A set of beliefs and practices that concern humanity’s relationship with the spiritual, the supernatural, and reality. scale — Degrees of magnification, or perspective, used to measure time, space, and size. science — An approach to discovering knowledge about the natural world that relies on testing ideas through observation or experiment. scientific notation — A method of expressing very large and very small numbers to avoid using the many zeros that would be required otherwise. thresholds of increasing complexity — Moments in the history of the Universe when specific ingredients under the right “Goldilocks Conditions” come together to create something new and more complex. Universe — All the matter and energy in existence, as well as the space that contains it. version — An interpretation of a matter from a particular viewpoint; something a little different from others of the same type |
Cosmology and Faith An illustration of multiple worlds by 18th-‐century mathematician Leonhard Euler © Science Source By John F. Haught Since the beginning of human existence on our planet, people have asked questions of a religious nature. For example, what happens to the dead? Human beings have always wondered how things hang together. Our minds spontaneously look for connections, and we remain restless until we find them. Nothing is really intelligible unless we can relate it to other things. This is why science is such a satisfying adventure. Its mathematical principles tightly unify everything that goes on in the cosmos. Every occurrence, science tells us, is subject to the same fundamental physical laws everywhere. You can be sure, for example, that if you travel to another galaxy in our Big Bang Universe you will find the same laws of physics and chemistry operative there as on Earth. Although the Universe unfolds in rich diversity, it rests upon an underlying physical and mathematical simplicity. Before modern science came along our ancestors were not aware of the physical universality that ties all of nature together. Nevertheless, our ancestors were just as interested in finding connections as we are. The main way in which they brought coherence to their experience of things and events was to tell stories about them. These stories often took the form of myths about cosmic, biological, and human origins. Understanding the origin of things apparently reduces human anxiety in the face of the unknown. We still need stories. Big history is a good example of the human longing for narrative coherence. We want to understand, for example, how life is tied into physical processes and how the history of human beings on Earth is bonded to the natural world that gave birth to us. Science now allows us to tell a whole new story about our connection to nature. Remarkably, over the last two centuries the natural sciences have increasingly demonstrated that the Universe itself has a history and that human life is a relatively new chapter in the cosmic story. We did not float in from some other world. We blossomed gradually from roots that extend all the way back to the Big Bang. It is enormously satisfying now to be able to tell the story of the emergence of atoms, stars, planets, cells, organisms, and minds. A 1784 diagram of the Milky Way by astronomer William Herschel. © Science Source What about religion? Science and history both try to understand how things hang together, but religions do too. Since the beginning of human existence on our planet, most people have asked questions of a religious nature. For example, what happens to the dead? Are they somehow still connected to the world of the living? In his insightful book The Broken Connection, psychiatrist Robert Jay Lifton observes that in the scientific age the bonds our ancestors felt between the living and dead have been weakened or completely broken. Scientifically educated people now often question the connection that religions professed to find between our present life and a wider world of sacred mystery. Nevertheless, many of us still ask religious questions. Why, for example, does anything exist at all? Why do living beings suffer? What happens when we die? Why do human beings have a sense of rightness and wrongness? How can we find a meaning for our lives? Can we ever find final release from concerns over sickness, oppression, isolation, and guilt? Where can we find perfection? What is really going on in the Universe? Responses to these religious questions have usually taken the form of myths and other kinds of narratives. To most religions the “really real” world is infinitely larger than the visible one available to scientific study. Religions try to connect people to this wider world. Ever since the earliest stories and oral traditions, most people have had an intuition that the world is large enough to include spirits, gods, and long-departed ancestors. Religions strive to break through the physical limits that cut human existence off from the mysterious worlds to which their symbols and stories point. Religions seek to mend the sense of broken connection that stems from the experience of meaninglessness, guilt, pain, and death. Major religious traditions such as Buddhism, Hinduism, Judaism, Christianity, and Islam still hold out the hope of salvation from everything that hems us in or holds us down, including the fact that everything eventually perishes. It is therefore not hard to understand why religions have been so important to most people throughout history and around the globe. Each of Earth’s main religious traditions has countless tributaries and off-shoots. Religion on Earth is so complex and diverse that it almost resembles a rain forest. Since religions are so central to the history of human existence on our planet, they rightly attract the interest of natural scientists and not just of historians and theologians. Any objective survey of big history, therefore, cannot ignore the dominant role that religions have played in shaping the consciousness of most people who have ever lived. The question of science and faith In the age of science, however, what are we to make of religions and their sense of a connection between our present existence and a larger, scientifically unavailable life-world? Hasn’t science made religious symbols, narratives, and teachings unbelievable? For the sake of simplicity, as we address these questions let us refer to the whole body of religious hopes, stories, doctrines, speculation, prayers, and rituals as “faith.” More fascinating questions arise for your consideration: Can human minds shaped by faith traditions that stem from a prescientific era honestly take modern science seriously? Or, if you develop a sense of big history, can you still honestly accept the teachings of your faith tradition if you have one? Does belief in God, for example, contradict science, as many educated people now maintain? Isn’t it hard to be both a serious scientist and a person of faith? Or is there a way of making a plausible con- nection between science and faith? Even though it is not my task to answer such questions, it is appropriate at least to take note of their existence, especially since humans and their religious instincts are as much a part of nature as rocks and rivers. What does it say about the Universe that it has recently given birth to conscious beings who want to connect their lives to worlds that science cannot see? Many scientists, philosophers, and other skeptics wish that religious faith would just go away so that only science would remain to fill our minds and aspirations. Others, however, think that scientific discoveries, including our new sense of cosmic history, still raise questions that science alone is powerless to address. For example, why does the Universe exist in the first place? Is anything of lasting significance working itself out in the 14-billion-year-old cosmic story? Is there any point to it all? What are we supposed to be doing with our lives if we are a part of a Universe that is still coming into being? Is there any solid reason for hope in the future? There are at least three main ways of responding to questions that science raises for people of faith: Shape your own answers, make your own connections, and find your own way of understanding the beginning and how things “hang together.” For most people these are questions that will not just slip quietly away. For Further Discussion Think about the conflict, contrast, and convergence ideas that were presented in the Haught article—what do you think makes the most sense and how can you logically argue for your side? In the Questions Area below, post the side that makes the most sense and provide two reasons that support your choice. Author Bio John F. Haught is a Roman Catholic theologian and senior research fellow at the Woodstock Theological Center at Georgetown University, in Washington, D.C. He established the Georgetown Center for the Study of Science and Religion and is the author of numerous books, including Science and Faith: A New Introduction (Mahwah, NJ: Paulist Press, 2012). Image Credits An illustration of multiple worlds by 18th-century mathematician Leonhard Euler© Science Source A 1784 diagram of the Milky Way by William Herschel© Science Source Young Buddhist monks praying© Scott Stulberg/CORBIS |
Greek Origin Story: The Titans and the Gods of Olympus An illustration of Zeus crowned by Victory © Bettmann/CORBIS Compiled by Cynthia Stokes Brown This origin story comes from some of the earliest Greek writings that have survived. We know the Greek origin story from some of the earliest Greek literary sources that have survived, namely The Theogony and Works and Days, by Hesiod. This oral poet is thought to have been active sometime between 750 and 650 BCE, within decades of when the Homeric epics, The Iliad and The Odyssey, took the form in which we know them. Archeological findings support the creation story recorded in Hesiod’s work; pottery from the eighth century BCE depicts the gods and goddesses he describes. Before Hesiod told this patriarchal version, in which the first woman is the cause of much trouble, Pandora, whose name means “gift giver,” was known in oral tradition as a beneficent Earth goddess. In the beginning there was Chaos, a yawning nothingness. Out of the void emerged Gaia (the Earth) and other divine beings — Eros (love), the Abyss (part of the underworld), and the Erebus (the unknowable place where death dwells). Without male assistance, Gaia gave birth to Uranus (the Sky), who then fertilized her. From that union the first Titans were born — six males: Coeus, Crius, Cronus, Hyperion, Iapetus, and Oceanus, and six females: Mnemosyne, Phoebe, Rhea, Theia, Themis, and Tethys. After Cronus (time) was born, Gaia and Uranus decreed no more Titans were to be born. Cronus castrated his father and threw the severed genitals into the sea, from which arose Aphrodite, goddess of love, beauty and sexuality. Cronus became the ruler of the gods with his sister-wife, Rhea, as his consort. The other Titans became his court. Because Cronus had betrayed his father, he feared that his offspring would do the same. So each time Rhea gave birth, Cronus snatched up the child and ate it. Rhea hated this and tricked him by hiding one child, Zeus, and wrapping a stone in a baby’s blanket so that Cronus ate the stone instead of the baby. When Zeus was grown, he fed his father a drugged drink, which caused Cronus to vomit, throwing up Rhea’s other children and the stone. Zeus then challenged Cronus to war for the kingship of the gods. At last Zeus and his siblings, the Olympians, were victorious, and the Titans were hurled down to imprisonment in the Abyss. Zeus was plagued by the same concern as his father had been and, after a prophecy that his first wife, Metis, would give birth to a god greater than he, he swallowed Metis. But she was already pregnant with Athena, and they both made him miserable until Athena, the goddess of wisdom, civilization and justice, burst from his head — fully grown and dressed for war. Zeus was able to fight off all challenges to his power and to remain the ruler of Mt. Olympus, the home of the gods. One son of Titans, Prometheus, did not fight with fellow Titans against Zeus and was spared imprisonment; he was given the task of creating man. Prometheus shaped man out of mud, and Athena breathed life into the clay figure. Prometheus made man stand upright as the gods did and gave him fire. Prometheus tricked Zeus, and to punish him, Zeus created Pandora, the first woman, of stunning beauty, wealth, and a deceptive heart and lying tongue. He also gave Pandora a box she was commanded never to open, but eventually her curiosity got the best of her, and she opened the box to release all kinds of evil, plagues, sorrows, and misfortunes, and also hope, which lay at the bottom of the box. For Further Discussion Which two origin stories are the most similar and which are the most different? Explain your answer in the Questions Area below. Sources www.greekmythology.com David Leeming and Margaret Leeming, A Dictionary of Creation Myths (New York and Oxford: Oxford University Press, 1994), 221. Image Credits |
Approaches to Knowledge By Bob Bain, adapted by Newsela How do people create knowledge? It starts by being puzzled, curious, or even confused about the world. There’s a sense of wonder in it all. Here in a library, surrounded by books, I’ve set out to write about knowledge. Libraries make such appropriate places to discuss knowledge because their purpose is to store knowledge — that’s why communities build them. In many ways, libraries are repositories of collective learning, an idea that is very important in the Big History course. In this library and others, knowledge exists in many forms: books, maps, films, videos, CDs, and, of course, textbooks. The Big History class does not have a textbook, but it’s still useful to think about them and the knowledge within. I’ll tell you how I approached textbooks when I was a student and how most of my high school and college students approach their textbooks. They typically ask one big question: “How do we get the stuff out of that textbook and into our heads or, more important, onto the tests?” And frankly, that was the question I asked as a student: “How can I get the facts out of the textbook and onto the test?" Main Reading Room at the U.S. Library of Congress, courtesy of Carol McKinney Highsmith Archive, The Library of Congress Big History asks questions about knowledge In Big History we ask a very different question: “How did that knowledge get into the textbook?” That is, in Big History we wonder, “How did people discover the facts or create the ideas that are in our textbooks or in our courses?” Did you ever wonder how people create knowledge? Well, in this course you are going to meet many people who discovered or created the information that is in your textbooks. You will meet cosmologists, physicists, geologists, biologists, historians, and more. They are excited to tell you what they have learned. But they are also excited to tell you how they learned it. They are going to tell you how people in their field approach knowledge, the questions that interest them, and how they used intuition, authority, logic, and evidence to support their claims. In Big History, we want you to pay attention to the questions these scientists and scholars ask and the tools and evidence they use to answer their questions. Questions, tools, and evidence! Let’s look more carefully at how scholars use questions, tools, and evidence to create or discover ideas, facts, and knowledge. Most of the scholars you’ll meet in this course begin their investigations with questions. They are puzzled, curious, or even baffled about the world around them. Sometimes their inquiry begins in wonder. Unlike textbooks that place questions at the end of learning, scholars pose the questions first and use them to drive forward their learning. Galileo Explaining Moon Topography to Skeptics by Jean-Leon Huens © National Geographic Society/Corbis Have you noticed that your teacher, the Big History units, and David Christian’s videos all use questions — big questions — to launch your study? Before conducting an inquiry, scholars speculate or make a thoughtful guess about what they’ll learn. We often call these thoughtful guesses “conjectures” or “hypotheses.” But a question or a hypothesis isn’t knowledge yet. Scholars need to gather information to answer their questions. As you’ll learn in later units, sometimes people create or use new tools to help them gather new information. For example, Galileo used a telescope he made to collect new data about the heavens and the planets. Scholars turn information into evidence to support claims Gathering information does not automatically answer scholars’ questions. The information must also be organized, analyzed, and then evaluated to see if it answers the initial or driving questions. Scholars may then make claims that answer their questions, and use the information as evidence to support their claims. The stronger the evidence, the better the support for the claim — and the greater chance it has to enter a textbook, for others to learn about it. Scholars must show how they answered their questions Let’s review. In this essay, I wondered how knowledge gets in textbooks and, in answer to my question, I have described a few steps: First, scholars have questions or they are curious or puzzled about something.Second, they make a conjecture — a thoughtful guess or hypothesis.Next, they gather information to answer the question, often using new tools in the process.They then analyze the information, think about it, and, perhaps, use some of it to answer their question.Scholars use information as evidence to support or make their claims.When claims become well supported, they enter textbooks for students to learn. First, scholars have questions or they are curious or puzzled about something. Second, they make a conjecture — a thoughtful guess or hypothesis. Next, they gather information to answer the question, often using new tools in the process. They then analyze the information, think about it, and, perhaps, use some of it to answer their question. Scholars use information as evidence to support or make their claims. When claims become well supported, they enter textbooks for students to learn. But the scholars’ work is still not finished. They also must share what they learned and show how they learned it. Why do they have to show how they learned it? Isn’t simply telling what they learned enough? Why must they also explain how they conducted their investigation, how they analyzed their information, and how they supported their claims? Scholars want to contribute to collective learning. They want people to see how they arrived at their claims and what evidence supports the claims. They do not want people to simply trust their claims based only on intuition, logic, or authority. Scholars also want others to improve their claims. This might involve using new tools or new methods to gather new evidence to support or challenge the claims. Or it might mean asking a different question entirely. Different approaches to knowledge All the scholars you meet — whether archeologists, anthropologists, biologists, or experts in another field — ask important questions. They all make conjectures, gather data, and analyze it to make claims, but there are differences among and between these individuals. While they all ask important questions, make conjectures, gather data, and analyze it to make claims, there are differences among and between these scholars. They all begin their investigations asking questions, but they ask different questions. They all have ways to gather data, but they often have different ways to gather data. As you meet the instructors in this course, do more than just learn what they are teaching; try as well to understand how they do their work, what questions they ask, and how they answer their questions. You might ask each of them: What are the big questions that have interested you and driven you to personally pursue the answers?What were your guesses, speculations, and hypotheses?How did you collect your evidence?Where did you see the patterns in your evidence? What did those patterns seem to indicate?What were your biggest ideas?How did you make your ideas public?Why should others believe your ideas?When and why have you changed your mind? What are the big questions that have interested you and driven you to personally pursue the answers? What were your guesses, speculations, and hypotheses? How did you collect your evidence? Where did you see the patterns in your evidence? What did those patterns seem to indicate? What were your biggest ideas? How did you make your ideas public? Why should others believe your ideas? When and why have you changed your mind? Make sure to pay attention to big questions that haven’t been answered. These are questions that you and your friends might take up. Who knows? Maybe you can contribute to the textbooks of the future. Big History’s approach to knowledge As you might have already guessed, in Big History we ask lots of big questions. We’re going to ask questions about the physical world, the living world, and the human world. This will require us to use many different approaches to knowledge. One of the most exciting things about Big History is that we will use ideas that come from many different places. That is why you’re going to meet such a great variety of people who have contributed to our collective learning. And why we want to give you the chance to ask, “How did that knowledge get into the textbook?” For Further Discussion The ability to come up with good, researchable questions is something that we have learned that all scholars do, but how do they come up with those questions? What are some strategies you might use in figuring out how to ask the right questions when thinking about historical research and inquiry? Please share your strategies in the Questions Area below [Sources and attributions] |
Judeo-Christian Origin Story: Genesis Compiled by Cynthia Stokes Brown This story comes from the first book of the Old Testament, the sacred source book of both Judaism and Christianity. This biblical story comes from Genesis, the first book of the Old Testament, which is the sacred sourcebook of both Judaism and Christianity. In Genesis this story is followed immediately by a second creation story, in which humans are created first, followed by plants and animals. These stories were written down in the first millennium BCE and evolved into the form in which we know them around 450 BCE, some 2460 years ago. Genesis: Chapter 1 In the beginning when God created the heavens and the earth, the earth was a formless void, and darkness was over the surface of the deep, and the Spirit of God was hovering over the waters. And God said, “Let there be light,” and there was light. God saw that the light was good, and he separated the light from the darkness. God called the light “day,” and the darkness he called “night.” And there was evening, and there was morning — the first day. And God said, “Let there be a dome between the waters to separate water from water.” So God made the dome and separated the water under the dome from the water above it. And it was so. God called the dome “sky.” And there was evening, and there was morning — the second day. And God said, “Let the water under the sky be gathered to one place, and let dry ground appear.” And it was so. God called the dry ground “land,” and the gathered waters he called “seas.” And God saw that it was good. Then God said, “Let the land produce vegetation: seed-bearing plants and trees on the land that bear fruit with seed in it, of every kind.” And it was so. The land produced vegetation: plants bearing seed of every kind and trees bearing fruit with seed in it of every kind. And God saw that it was good. And there was evening, and there was morning — the third day. A detail from The Creation of the Sun, Moon, and Plants by Michelangelo Buonarroti © Bettmann/CORBIS And God said, “Let there be lights in the dome of the sky to separate the day from the night, and let them serve as signs to mark sacred times, and days and years, and let them be lights in the dome of the sky to give light on the earth.” And it was so. God made two great lights — the greater light to govern the day and the lesser light to govern the night. He also made the stars. God set them in the dome of the sky to give light on the earth, to govern the day and the night, and to separate light from darkness. And God saw that it was good. And there was evening, and there was morning — the fourth day. And God said, “Let the water teem with living creatures, and let birds fly above the earth across the dome of the sky.” So God created the great creatures of the sea and every living thing of every kind that moves in the teeming water, and every winged bird of every kind. And God saw that it was good. God blessed them and said, “Be fruitful and increase in number and fill the water in the seas, and let the birds increase on the earth.” And there was evening, and there was morning — the fifth day. And God said, “Let the land produce living creatures of every kind: the livestock, the creatures that move along the ground, and the wild animals, each of every kind.” And it was so. God made the wild animals of every kind, the livestock of every kind, and all the creatures that move along the ground of every kind. And God saw that it was good. And God said, “Let the water teem with living creatures, and let birds fly above the earth across the dome of the sky.” So God created the great creatures of the sea and every living thing of every kind that moves in the teeming water, and every winged bird of every kind. And God saw that it was good. God blessed them and said, “Be fruitful and increase in number and fill the water in the seas, and let the birds increase on the earth.” And there was evening, and there was morning — the fifth day. And God said, “Let the land produce living creatures of every kind: the livestock, the creatures that move along the ground, and the wild animals, each of every kind.” And it was so. God made the wild animals of every kind, the livestock of every kind, and all the creatures that move along the ground of every kind. And God saw that it was good. Then God said, “Let us make humankind in our image, in our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.” So God created humankind in his own image, in the image of God he created them; male and female he created them. God blessed them and said to them, “Be fruitful and increase in number; fill the earth and subdue it. Rule over the fish in the sea and the birds in the sky and over every living creature that moves on the ground.” Then God said, “I give you every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food. And to all the beasts of the earth and all the birds in the sky and all the creatures that move along the ground — everything that has the breath of life in it — I give every green plant for food.” And it was so. God saw all that he had made, and it was very good. And there was evening, and there was morning — the sixth day. Thus the heaven and the earth were finished, with all their multitudes. And on the seventh day God rested from all the work that he had done in creation. God blessed the seventh day and hallowed it because on it God rested from all the work that he had done in creation.* For Further Discussion How is the Judeo-Christian origin story similar to the Greek origin story? How is it different? Share your answers in the Questions Area below. Sources New International Version, Genesis retrieved May 2011 from www.biblegateway.com Image Credits Detail of God from Creation of Adam by Michelangelo Buonarroti© Alinari Archives/CORBIS A detail from The
Creation of the Sun, Moon, and Plantsby Michelangelo Buonarroti© Bettmann/CORBIS |
Iroquois Origin Story: The Great Turtle Illustration of the Iroquois Prayer of Thanksgiving © National Geographic Society/CORBIS Compiled by Cynthia Stokes Brown The Iroquois people of North America spoke this story. Settlers from Europe wrote it down. This story comes from the Iroquois people in North America. In the 1400s they formed a federation of five separate tribes in what is now New York State. The Iroquois did not use writing, so they told this story orally until settlers from Europe wrote it down. The first people lived beyond the sky because there was no earth beneath. The chief’s daughter became ill, and no cure could be found. A wise old man told them to dig up a tree and lay the girl beside the hole. People began to dig, but as they did the tree fell right through the hole, dragging the girl with it. Below lay an endless sheet of water where two swans floated. As the swans looked up, they saw the sky break and a strange tree fall down into the water. Then they saw the girl fall after it. They swam to her and supported her, because she was too beautiful to allow her to drown. Then they swam to the Great Turtle, master of all the animals, who at once called a council. When all the animals had arrived, the Great Turtle told them that the appearance of a woman from the sky was a sign of good fortune. Since the tree had earth on its roots, he asked them to find where it had sunk and bring up some of the earth to put on his back, to make an island for the woman to live on. The swans led the animals to the place where the tree had fallen. First Otter, then Muskrat, and then Beaver dived. As each one came up from the great depths, he rolled over exhausted and died. Many other animals tried, but they experienced the same fate. At last the old lady Toad volunteered. She was under so long that the others thought she had been lost. But at last she came to the surface and before dying managed to spit out a mouthful of dirt on the back of the Great Turtle. It was magical earth and had the power of growth. As soon as it was as big as an island, the woman was set down on it. The two white swans circled it, while it continued to grow, until, at last, it became the world island as it is today, supported in the great waters on the back of the Turtle.* Engraving of a tattooed Iroquois © CORBIS For Further Discussion Writers often rely on origin stories to serve as the inspiration for books and films. Can you think of any examples of modern works that share elements of The Great Turtle? Sources Cottie Burland, North American Indian Mythology, Rev. ed. (New York: Peter Bedrick Books, 1985), 66. Image Credits |
Origin Stories Introduction By Cynthia Stokes Brown All humans yearn to know where we came from and how our world began. We may have different stories, but they all serve
a similar purpose. Everywhere around the world people tell stories about how the Universe began and how humans came into being. Scholars, namely anthropologists and ethnologists, call these tales “creation myths” or “origin stories.” In comic-book lingo there is a specialized meaning for “origin stories.” They are accounts that relate how superheroes got their superpowers. Some origin stories are based on real people and events, while others are based on more imaginative accounts. Origin stories can contain powerful, emotional symbols that convey profound truths, but not necessarily in a literal sense. In the United States, many people tell stories about Santa Claus. But everyone, except young children, knows that he is a symbol of love and generosity, not a person who actually exists. Many cultures
tell stories that seem strange to outsiders but have deep meaning to group members. When people in a culture become literate, they write down their origin stories. But the stories frequently go back way before written records, to when people told them aloud. This is called an “oral tradition.” Multiple versions of each story often exist, since people — from group to group and generation to generation — may change them slightly as they retell them. I have chosen to summarize, in writing, five origin stories from
a wide number of places and eras — feel free to tell them aloud to each other. [Sources and attributions] |
Chinese Origin Story: Pan Gu and the Egg of the World Compiled by Cynthia Stokes Brown First written down about
1,760 years ago, this
story of how the Universe
began was told orally long
before that. This origin story comes from Chinese culture. It was first written down
about 1,760 years ago, roughly 220 — 265 CE, yet it must have been told orally
long before that. In the beginning was a huge egg containing chaos, a mixture of yin
and yang — female-male, aggressive-passive, cold-hot, dark-light, and
wet-dry. Within this yin and yang was Pan Gu, who broke forth from
the egg as the giant who separated chaos into the many opposites,
including Earth and sky. Pan Gu stood in the middle, his head touching the sky, his feet planted
on Earth. The heavens and the Earth began to grow at a rate of 10 feet a day,
and Pan Gu grew along with them. After another 18,000 years the
sky was higher and Earth was thicker. Pan Gu stood between them
like a pillar 30,000 miles in height, so they would never again join. When Pan Gu died, his skull became the top of the sky, his breath
became the wind and clouds, his voice the rolling thunder. One eye
became the Sun and the other the Moon. His body and limbs turned
into five big mountains, and his blood formed the roaring water.
His veins became roads and his muscles turned to fertile land. The
innumerable stars in the sky came from his hair and beard, and flowers
and trees from his skin. His marrow turned to jade and pearls.
His sweat flowed like the good rain and the sweet dew that nurtures
all things on Earth. Some people say that the fleas and the lice on
his body became the ancestors of humanity. Sources David Leeming and Margaret Leeming, A Dictionary of Creation Myths
(New York and Oxford: Oxford University Press, 1994), 47 – 50. Image Credits An illustration of Pan Gu from the Sancai Tuhui, public domain
Cassia-Tree Moon
© Asian Art & Archaeology, Inc./CORBIS |
Mayan Origin Story: The Popul Vuh Creation by Diego Rivera © Christie’s Images/CORBIS Compiled by Cynthia Stokes Brown This is the beginning of a long, complex story called the Popol Vuh which means “council book.” It was told by the Mayans who long ago lived in theYucatán Peninsula of Mexico. This origin story was told by the Mayas, who lived in the Yucatán Peninsula of Mexico from around 250 CE to 900 CE. It’s the beginning of a long, complex story called the Popol Vuh (literally the “council book”), first translated into alphabetic text from Mayan hieroglyphics in the 16th century. Now it still ripples, now it still murmurs, still sighs, and is empty under the sky. There is not yet one person, not one animal, bird, fish or tree. There is only the sky alone; the face of earth is not clear, only the sea alone is pooled under all the sky. Whatever might be is simply not there. There were makers in the sea, together called the Plumed Serpent. There were makers in the sky, together called the Heart of Sky. Together these makers planned the dawn of life. The earth arose because of them. It was simply their word that brought it forth. It arose suddenly, like a cloud unfolding. Then the mountains were separated from the water. All at once great mountains came forth. The sky was set apart, and the earth was set apart in the midst of the waters. Then the makers in the sky planned the animals of the mountains — the deer, pumas, jaguars, rattlesnakes, and guardians of the bushes. Then they established the nests of the birds, great and small. “You precious birds; your nests are in the trees and bushes.” Then the deer and birds were told to talk to praise their makers, to pray to them. But the birds and animals did not talk; they just squawked and howled. So they had to accept that their flesh would be eaten by others. The makers tried again to form a giver of respect, a creature who would nurture and provide. They made a body from mud, but it didn’t look good. It talked at first but then crumbled and disintegrated into the water. Then the Heart of Sky called on the wise ones, the diviners, the Grandfather Xpiyacoc and the Grandmother Xmucane, to help decide how to form a person. The Grandparents said it is well to make wooden carvings, human in looks and speech. So wooden humans came into being; they talked and multiplied, but there was nothing in their minds and hearts, no memory of their builder, no memory of Heart of Sky. Then there came a great destruction. The wooden carvings were killed when the Heart of Sky devised a flood for them. It rained all day and all night. The animals came into the homes of the wooden carvings and ate them. The people were overthrown. The monkeys in the forest are a sign of this. They look like the previous people — mere wooden carvings. The story continues with the final people being made from corn, an important crop that enabled the Maya to move from being a hunting-and-gathering society to a more complex civilization. For Further Discussion Are you having any trouble filling out your chart? Ask for help—or offer it—in the Questions Area below. Sources Edited from Dennis Tedlock, Popol Vuh: The Mayan Book of the Dawn of Life Rev. ed. (New York: Simon and Schuster, 1996), 64 – 73. Image Credits Creation by Diego Rivera© Christie’s Images/CORBIS |
Modern Scientific Origin Story: The Big Bang Planetary nebula NGC 6210 in Hercules Constellation © ESA/Hubble and NASA By Cynthia Stokes Brown From vast nothingness to a Universe of stars and galaxies and our own Earth. This version of modern science’s origin story is condensed and interpreted from a great body of historical and scientific information. In the beginning, as far as we know, there was nothing. Suddenly, from a single point, all the energy in the Universe burst forth. Since that moment 13.8 billion years ago, the Universe has been expanding — and cooling down as it gets bigger. Gradually energy cooled enough to become matter. One electron could stay in orbit around one proton to become an atom of hydrogen. Great clouds of hydrogen swirled around space until gravity pulled some atoms so close together that they began to burn as stars. Stars swirled together in giant clusters called galaxies; now there are galaxies numbering in the billions. In the beginning, as far as we know, there was nothing. Suddenly, from a single point, all the energy in the Universe burst forth. Since that moment 13.8 billion years ago, the Universe has been expanding — and cooling down as it gets bigger. Gradually energy cooled enough to become matter. One electron could stay in orbit around one proton to become an atom of hydrogen. Great clouds of hydrogen swirled around space until gravity pulled some atoms so close together that they began to burn as stars. Stars swirled together in giant clusters called galaxies; now there are galaxies numbering in the billions. After each star burned up all its matter, it died in a huge explosion. The explosion generated so much heat that some atoms fused and got more and more complex, forming many different elements, including gold and silver. One giant star, our mother star, exploded and scattered clouds of gas containing all the elements needed to form living beings. About 5 billion years ago gravity pulled these atoms into a new star: our Sun. The leftover pieces of matter stuck to each other and formed eight planets, which revolve around the Sun. The third planet out, Earth, became our home. It was the perfect size — not too big, not too small — and the perfect distance from the Sun, not too far or too close. A thin crust formed over Earth’s hot interior, and the temperature was just right for water to form on parts of the surface. Gradually the chemicals in the water formed inside of membranes and got more complex until one-celled living organisms appeared, able to maintain themselves and reproduce. For 3 billion years these one-celled creatures reproduced almost exactly, but not quite. They gradually changed in response to their environment. But they also changed their environment. They learned to burn energy from the Sun, and they released oxygen into the atmosphere. The oxygen formed an ozone layer around Earth that protected life from the Sun’s rays. Eventually cells stuck together to form creatures with many cells. Plants and animals came out of the sea onto land and became ever more complex and aware, until about 100,000 years ago human beings evolved from a shared ancestor with species of apes.Humans could talk in symbols and sing, dance, draw, and cooperate more than the other animals could. Humans learned to write and to accumulate their learning so that it kept expanding. Humans increased in skills and in numbers until there were too many people and too few big animals in some places. Eventually cells stuck together to form creatures with many cells. Plants and animals came out of the sea onto land and became ever more complex and aware, until about 100,000 years ago human beings evolved from a shared ancestor with species of apes. Humans could talk in symbols and sing, dance, draw, and cooperate more than the other animals could. Humans learned to write and to accumulate their learning so that it kept expanding. Humans increased in skills and in numbers until there were too many people and too few big animals in some places. Then humans learned to grow their own food and herd their own animals. Some animals learned to cooperate with humans. This gave humans new sources of food and work energy, and they could live in larger and larger groups. These groups expanded into cities and empires, using more and more of the resources of Earth. Humans collaborated and learned collectively in more complex ways; they traveled, traded, and exchanged inventions, creating vast civilizations of astonishing beauty and complexity. Humans were always looking for more energy for their use. About 200 years ago we learned to use the energy from coal — trees that grew more than 300,000 years ago, then were buried underground. Humans learned to burn oil — animal remains buried long ago under the sea. Using these fossil fuels, humans began to change their climate quickly, as the gases released from burning these fuels ascended into the atmosphere. Now humans are in a predicament – our population is increasing rapidly, fossil fuels are running out, we are pushing many plants and other animals into extinction, and we are changing the climate. What are we humans going to do next?* |
Complexity & Thresholds By David Christian What does complexity mean, and why is it so important? What role has complexity played in getting us to the world we live in today? One of the central themes of this course is the idea of increasing complexity. In the 13.8 billion years since our Universe appeared, more and more complex things seem to have appeared—and we’re among the most complex of them all. So it’s natural for complex things to fascinate us. Besides, modern human society is so complex that learning how the Universe creates complexity can also teach us something about today’s world. But we shouldn’t assume there’s anything special about complexity or that complex things are necessarily any better than simple things. Remember that complexity can present challenges. What does complexity mean? That’s a tough question and there’s no universally accepted answer. We may feel intuitively that empty space is much simpler than a star, or that a human being is in some sense more complex than an amoeba. But what does that really mean? Here are some ideas that may help you think about complexity during this course. A continuum from simple to complex Complexity is a quality, like “hot” or “cold.” Things can be more or less simple and more or less complex. At one end is utmost simplicity, like the cold emptiness of intergalactic space. At the other extreme is the complexity of a modern city. The qualities of more complex things Here are three qualities that make some things more complex than others. Diverse ingredients: More complex things often have more bits and pieces, and those bits and pieces are more varied.Precise arrangement: In simpler things it doesn’t matter too much how the ingredients are arranged, but in complex things the bits and pieces are arranged quite precisely. Think of the difference between a car and all the bits and pieces of that car after it’s been scrapped and is lying in a junkyard.Emergent properties: Once the ingredients are arranged correctly, they can do things that they couldn’t do when they weren’t organized. A car can get you around; its component parts cannot. A car’s capacity to be driven is a quality that “emerges” once it’s been assembled correctly, which is why it’s called an “emergent property.” Diverse ingredients: More complex things often have more bits and pieces, and those bits and pieces are more varied. Precise arrangement: In simpler things it doesn’t matter too much how the ingredients are arranged, but in complex things the bits and pieces are arranged quite precisely. Think of the difference between a car and all the bits and pieces of that car after it’s been scrapped and is lying in a junkyard. Emergent properties: Once the ingredients are arranged correctly, they can do things that they couldn’t do when they weren’t organized. A car can get you around; its component parts cannot. A car’s capacity to be driven is a quality that “emerges” once it’s been assembled correctly, which is why it’s called an “emergent property.” Complexity is fragile There’s another important thing to remember about complexity. Complex things need just the right ingredients and they need to be assembled in just the right way. So, complex things are usually more fragile than simple things. And that means that after a time, they fall apart. If they are living creatures, we say they “die.” Death, or breakdown, seems to be the fate of all complex things, though it may take billions of years for a star to break down, and just a day or two for a mayfly to die. The Second Law of Thermodynamics Creating complex things is more difficult than creating simple things. The natural tendency of the Universe seems to be for things to get less and less organized. Think of your own house if you just let it be for a month. Tidying your room means arranging everything in just the right way; it takes work. But if you don’t care how it’s arranged you can just let it un-tidy itself naturally. The idea that the Universe tends naturally to get less ordered and less complex is expressed in one of the most fundamental of all the laws of physics: the Second Law of Thermodynamics. That’s one way of explaining why making complex things requires more work, and thus more energy, than making simple things. Why complexity is rarer than simplicity The Second Law of Thermodynamics explains why most of the Universe is simple. Intergalactic space is almost completely empty, extremely cold, and randomly organized. Complexity is concentrated in just a few places: inside galaxies and particularly around stars. Goldilocks Conditions You find complex things only where the conditions are just right for making them, where there are just the right environments, just the right ingredients, and just the right energy flows. We call these conditions “Goldilocks Conditions.” Remember the children’s story of the three bears? Goldilocks enters their house when they are out. She tastes their porridge and finds that the father bear’s is too hot, the mother bear’s is too cold, but the baby bear’s is just right. Complexity seems to appear only where the conditions are “just right.” So whenever we see complex things appearing, we can ask why the Goldilocks Conditions were “just right.” Here’s an example. You always need energy. So if there’s no energy flowing, it’s hard to build complexity. Think of a still, calm lake that’s been dammed. Not much is happening. Then imagine opening the gates of the dam and allowing the water to flow downhill. Now you have energy flowing—enough to drive a turbine that can create the electricity to power a computer. Now more complex things can happen. But of course there mustn’t be too much energy. If there’s too much water pressure then the turbine will be destroyed. So you need just the right amount of energy—not too little, not too much. Thresholds of increasing complexity In this course, we will focus on moments when more complex things seemed to appear, things with new emergent properties. We call these “threshold moments.” Examples include the appearance of the first stars in a Universe that had no stars, and the appearance of the first cities in societies that had never known cities before. Each time we cross one of these thresholds we’ll ask about the ingredients and the Goldilocks Conditions. And we’ll also ask what was new. What emergent properties do these new complex things have? There are many such turning points in Big History, but in this course we will focus mainly on eight threshold moments. Some thresholds took place at a very specific point in time, while others were more gradual and we can only approximate the turning point. If this were an astronomy course or a biology course, our choice of thresholds would undoubtedly be different. In fact, during this course we will see many important “turning points” that we could, perhaps, describe as “thresholds.” For Further Discussion Think about the your life in terms of thresholds of increasing complexity. What Goldilocks Conditions allowed your thresholds to emerge? What were the emergent properties? Post your answers in the Questions Area below. [Sources and attributions] |
The Graphic Biography below uses “Three Close Reads”. If you want to learn more about this strategy, click here. Reading 1: Skimming for gist This will be your quickest read. It should help you get the general idea of what the graphic biography will be about. Pay attention to the title, headings, images, and layout. Ask yourself: what is this graphic biography going to be about? Reading 2: Understanding content For this reading, you should be looking for unfamiliar vocabulary words, the major claim and key supporting details, and analysis and evidence. You should also spend some time looking at the images and the way in which the page is designed. By the end of the second close read, you should be able to answer the following questions: What were some challenges Chien-Shiung Wu faced as she became a physicist? How did she overcome these challenges?What does this comic mean by saying the Universe is “left-handed”? What role did Wu play in this discovery?Why was Wu’s 1956 experiment important to collective learning?Looking at just the images in this comic, what information does the artist tell you with the art? What were some challenges Chien-Shiung Wu faced as she became a physicist? How did she overcome these challenges? What does this comic mean by saying the Universe is “left-handed”? What role did Wu play in this discovery? Why was Wu’s 1956 experiment important to collective learning? Looking at just the images in this comic, what information does the artist tell you with the art? Reading 3: Evaluating and Corroborating In this read, you should use the graphic biography as evidence to support, extend, or challenge claims made in the course. At the end of the third read, you should be able to respond to these questions: Had you heard about Chien-Shiung Wu before reading this comic? Why do you think someone like Wu isn't featured in more of the big stories about collective learning? Now that you know what to look for, it’s time to read! Remember to return to these questions once you’ve finished reading. Dr. Wu and the Left-Handed Universe (Graphic Biography) Writer: Bennett Sherry Artist: Kay Shohini Chien-Shiung Wu is today known as the “First Lady of Physics.” Yet, many people don’t know her name. She broke barriers and disproved one of the fundamental laws of physics. Download the Graphic Biography PDF here or click on the image above. |
Evidence for an Expanding Universe By Cynthia Stokes Brown Born: November 20, 1889; Marshfield, Missouri. Died: September 28, 1953; San Marino, California. Edwin Hubble © SPL / Photo Researchers, Inc. In the course of five years, Edwin Hubble twice changed our understanding of the Universe, helping to lay the foundations for the Big Bang theory. First he demonstrated that the Universe was much larger than previously thought, then he proved that the Universe is expanding. Early Life and Education Edwin Powell Hubble, the son of an insurance executive, was born in Marshfield, Missouri, on November 20, 1889, and moved to Wheaton, Illinois, a suburb of Chicago, soon after. Growing up, he was more outstanding as an athlete than as a student, although he did earn good grades in every subject (except spelling). He won seven first-places and a third place in a single high school track-and-field meet in 1906. That year he also set the Illinois high school record in the high jump. At the University of Chicago, Hubble studied mathematics, astronomy, and philosophy — and played for the school’s basketball team. He graduated with a bachelor of science in 1910, and then spent 1911 to 1914 earning his master’s as one of Oxford University’s first Rhodes scholars. Though he studied law and Spanish there, his love of astronomy never diminished. Edwin Hubble © Science Source At Yerkes Observatory Moving back to the United States, Hubble enrolled as a graduate student at the University of Chicago and studied the stars at their Yerkes Observatory in Wisconsin. It was here that he began to study the faint nebulae that would be the key to his greatest discoveries. After receiving his doctorate in astronomy from the University of Chicago in 1917, he won an offer to join the staff at the prestigious Mount Wilson Observatory, near Pasadena, California. At Mount Wilson Observatory Arriving at Mount Wilson in 1919, he joined an astronomy establishment that was just beginning to grasp cosmic distances. The key to that effort was work that had been done studying Cepheid variable stars, roughly a decade earlier, by Henrietta Swan Leavitt at Harvard. These stars brighten and dim in a predictable pattern, and their distance from us can be worked out by measuring how bright they appear to us. Another astronomer at the observatory, Harlow Shapley, built on Leavitt’s findings and shocked the world with his conclusions about the size of the Milky Way. Using the Cepheid variables, Shapley judged that the Milky Way was 300,000 light years across — 10 times bigger than previously thought. Hubble began his work at Mount Wilson just as the new 2.56-meter Hooker Telescope, the most powerful on Earth, was completed. With it, he was able to peer into the sky with greater detail than anyone had previously. After years of observation, Hubble made an extraordinary discovery. In 1923 he spotted a Cepheid variable star in what was known as the Andromeda Nebula. Using Leavitt’s techniques, he was able to show that Andromeda was nearly 1 million light years away and clearly a galaxy in its own right, not a gas cloud. Hubble used the Hooker Telescope at Mount Wilson Observatory for some of his most important discoveries. © Emilio Segrè Visual Archives / American Institute of Physics / Photo Researchers, Inc. Hubble then went on to discover Cepheids in multiple nebulae, and proved, in a 1924 paper called “Cepheids in Spiral Nebula,” that galaxies existed outside our own. Overnight, he became the most famous astronomer in the world, and people everywhere had to get used to the fact that the Universe was far vaster than anyone had imagined. Shapley, for one, was shaken by the news. He wrote Hubble, “I do not know whether I am sorry or glad to see this break in the nebular problem. Perhaps both.” In 1926, while developing a classification system for galaxies, Hubble discovered an odd fact: Almost every galaxy he observed appeared to be moving away from the Earth. He knew this because the light coming from the galaxies exhibited redshift. Light waves from distant galaxies get stretched by the expansion of the Universe on their way to Earth. This shifts visible light toward the red end of the spectrum. Building on the work of Vesto Slipher, who measured the redshifts associated with galaxies more than a decade earlier, Hubble and his assistant, Milton Humason, discovered a rough proportionality between the distances and redshifts of 46 galaxies they studied. By 1929 they had formulated what became known as Hubble’s Law. Hubble’s Law basically states that the greater the distance of a galaxy from ours, the faster it recedes. It was proof that the Universe is expanding. It was also the first observational support for a new theory on the origin of the Universe proposed by Georges Lemaitre: the Big Bang. After all, an expanding Universe must once have been smaller. Timeline of Hubble's life. Click here for a larger version. Download PDF. Later Life Hubble achieved scientific superstardom for his discoveries and is still considered a brilliant observational astronomer. He ran the Mount Wilson Observatory for the rest of his life, popularized astronomy through books and lectures, and worked to have astronomy recognized by the Nobel Prize committee. He also played a pivotal role in the design and construction of the Hale Telescope, on Palomar Mountain, California. At 5.08 meters, the Hale was four times as powerful as the Hooker Telescope and existed as the most advanced telescope on Earth for some time. After its completion in 1948, Edwin Hubble was given the honor of first use. When asked by a reporter what he expected to find, Hubble answered: “We hope to find something we hadn’t expected.” For Further Discussion Think about the following question and write your response and any additional questions you have in the Questions Area below. How did Hubble’s work support the Big Bang theory? [Sources and attributions] |
A sun-centered view of the universe By Cynthia Stokes Brown Born: February 19, 1473; Torun, Poland. Died: May 24, 1543; Frombork, Poland. An engraving of Copernicus © Copernicus/PoodlesRock/CORBIS In the middle of the 16th century a Catholic, Polish astronomer, Nicolaus Copernicus, synthesized observational data to formulate a comprehensive, Sun-centered cosmology, launching modern astronomy and setting off a scientific revolution. Renaissance man Have you ever heard the expression “Renaissance man”? First coined in the early 20th century, the phrase describes a well-educated person who excels in a wide variety of subjects or fields. The Renaissance is the name for a period in European history, the 14th through the 17th centuries, when the continent emerged from the “Dark Ages” with a renewed interest in the arts and sciences. European scholars were rediscovering Greek and Roman knowledge, and educated Europeans felt that humans were limitless in their thinking capacities and should embrace all types of knowledge. Nicolaus Copernicus fulfilled the Renaissance ideal. He became a mathematician, an astronomer, a church jurist with a doctorate in law, a physician, a translator, an artist, a Catholic cleric, a governor, a diplomat, and an economist. He spoke German, Polish, and Latin, and understood Greek and Italian. Family and studies You might guess that Copernicus’s parents must have been extremely wealthy to provide him with such an education. While that was the case, the family history was a bit more complicated. Nicolaus was born on February 19, 1473, in Torun, in the approximate center of what is now Poland. His father, named Nicolaus Koppernigk, was a copper merchant from Krakow, and his mother, Barbara Watzenrode, was the daughter of a wealthy Torun merchant. Nicolaus was the youngest of four children; he had a brother and two sisters. His father died when he was 10 and his mother at about the same time. His mother’s brother adopted Nicolaus and his siblings and secured the future of each of them. This maternal uncle, Lucas Watzenrode, was a wealthy, powerful man in Warmia, a small province in northeast Poland under the rule of a prince-bishop. Since 1466 Warmia had been part of the kingdom of Poland, but the king allowed it to govern itself. Watzenrode became the prince-bishop in Warmia when Copernicus was 16. Three years later he sent Copernicus and his brother to the University of Krakow, where Copernicus studied from 1492 to 1496. He was in his first year at the university when Columbus sailed to a continent that was then unknown in Europe. Copernicus changed his last name, Koppernigk, to its Latin version while at the university, since scholars used Latin as their common language. At Krakow Copernicus studied mathematics and Greek and Islamic astronomy. After studying at Krakow, Copernicus’s uncle sent him to Italy, where he studied law at the University of Bologna for four years, and then medicine at the University of Padua for two years. These were two of the earliest and best European universities and Copernicus had to travel two months by foot and horseback to reach Italy. At these universities, Copernicus began to question what he was taught. For example, his professors at Krakow taught about both Aristotle’s and Ptolemy’s views of the Universe. However, Copernicus became aware of the contradictions between Aristotle’s theory of the Earth, the Sun and the planets as a system of concentric spheres and Ptolemy’s use of eccentric orbits and epicycles. Even though his professors believed that the Earth was in the center of the Universe and it did not move, Copernicus began to question those ideas. While at the University of Padua, there is some evidence that he had already developed the idea of a new system of cosmology based on the movement of the Earth. Copernicus returned to Warmia in 1503, at age 30, to live in his uncle’s castle and serve as his secretary and physician. He stayed at this job, which gave him free time to continue his observations of the heavens, until 1510, two years before his uncle’s death. Life as a canon Copernicus’s uncle arranged for him a secure life as a church canon. A canon was a member of a group of canons, called a chapter, who together were responsible for administering all aspects of a cathedral. Canons were encouraged, but not required, to take full orders as a priest. They could take minor orders, but even minor orders included a vow of celibacy. It is not clear whether Copernicus was ever ordained as a priest. It may be that he took only minor orders, enough to be a canon. Due at least in part to the influence of his uncle, Copernicus was elected in 1497 a canon of the cathedral in Frombork (known as Frauenburg at the time), a town in Warmia on the Baltic Sea coast. Copernicus did not assume his position there until 1510, when he took a house outside the cathedral walls and an apartment inside a tower of the fortifications. He had many duties as canon, including mapmaking, collecting taxes and managing the money, serving as a secretary, and practicing medicine. He led a half-religious, half-secular life and still managed to continue his astronomical observations from his tower apartment. He conducted these with devices that looked like wooden yardsticks joined together, set up to measure the angular altitude of stars and planets and the angles between two distant bodies in the sky. He had a simple metal tube to look through, but no telescope had yet been invented. By 1514 Copernicus had written a short report that he circulated among his astronomy-minded friends. This report, called the Little Commentary, expounded his heliocentric theory. He omitted mathematical calculations for the sake of brevity, but he confidently asserted that the Earth both revolved on its axis and orbited around the Sun. This solved many of the problems he found with Ptolemy’s model, especially the lack of uniform circular motion. In 1520 the Teutonic Knights, a German Catholic military order that had Christianized the pagans in this area and controlled a large area along the Baltic Sea, attacked Frombork. They burned the whole town except for the cathedral. Soon, however, the Polish king drove the Knights out of Warmia, and the canons worked to rebuild the town. By 1531 the bishop-prince of Warmia believed that Copernicus had a mistress, Anna Schilling, whom he called his housekeeper. The next bishop-prince worked persistently to force Copernicus to give up his companion. Lutheran Protestantism was springing up nearby, as cities, dukes, and kings renounced their loyalty to the Catholic Church. The Catholic Church responded by trying to enforce more obedience to its rules. However, Copernicus and Schilling managed to keep seeing each other, although not living together, until much later when she moved to the city of Gdansk. The Copernican model from the Harmonica Macrocosmica atlas by Andreas Cellarius. Copernicus’s view of the Solar System from the 1661 Harmonica Macrocosmia by Cellarius © Bettmann/CORBIS A heliocentric theory By 1532 Copernicus had mostly completed a detailed astronomical manuscript he had been working on for 16 years. He had resisted publishing it for fear of the ensuing controversy and out of hope for more data. Finally, in 1541, the 68-year-old Copernicus agreed to publication, supported by a mathematician friend, Georg Rheticus, a professor at the University of Wittenberg, in Germany. Rheticus had traveled to Warmia to work with Copernicus, and then took his manuscript to a printer in Nuremberg, Johannes Petreius, who was known for publishing books on science and mathematics. Copernicus gave his master work the Latin title De Revolutionibus Orbium Coelestium (translated to English as On the Revolutions of the Celestial Spheres). In this work Copernicus began by describing the shape of the Universe. He provided a diagram to help the reader. In the diagram he showed the outer circle that contained all the fixed stars, much further away than previously believed. Inside the fixed stars were Saturn, then Jupiter and Mars, then Earth, Venus, and Mercury, all in circular orbits around the Sun in the center. He calculated the time required for each planet to complete its orbit and was off by only a bit. A summary of Copernicus’s theory 01 - The center of the Earth is not the center of the Universe, only of Earth’s gravity and of the lunar sphere.02 - The Sun is fixed and all other spheres revolve around the Sun. (Copernicus retained the idea of spheres and of perfectly circular orbits. In fact, the orbits are elliptical, which the German astronomer Johannes Kepler demonstrated in 1609.)03 - Earth has more than one motion, turning on its axis and moving in a spherical orbit around the sun.04 - The stars are fixed but appear to move because of the Earth’s motion. 01 - The center of the Earth is not the center of the Universe, only of Earth’s gravity and of the lunar sphere. 02 - The Sun is fixed and all other spheres revolve around the Sun. (Copernicus retained the idea of spheres and of perfectly circular orbits. In fact, the orbits are elliptical, which the German astronomer Johannes Kepler demonstrated in 1609.) 03 - Earth has more than one motion, turning on its axis and moving in a spherical orbit around the sun. 04 - The stars are fixed but appear to move because of the Earth’s motion. Timeline of Coperinicus's life. Click here for a larger version. Download PDF. Death and legacy Legend has it that Copernicus, in a sickbed when his great work was published, awoke from a stroke-induced coma to look at the first copy of his book when it was brought to him. He was able to see and appreciate his accomplishment, and then closed his eyes and died peacefully, on May 24, 1543. Thus he avoided both scorn and praise. Copernicus was thought to be buried in the cathedral at Frombork, but no marker existed. Some of his bones were finally identified there, with a DNA match from a strand of his hair found in a book owned by him, and in 2010 he was given a new burial in the same spot, now marked with a black granite tombstone. The Roman Catholic Church waited seven decades to take any action against On the Revolutions of the Celestial Spheres. Why it waited so long has been the subject of much debate. In 1616 the church issued a decree suspending On the Revolutions of the Celestial Spheres until it could be corrected and prohibiting any work that defended the movement of Earth. A correction appeared in 1620, and in 1633 Galileo Galilei was convicted of grave suspicion of heresy for following Copernicus’s position. Scholars did not generally accept the heliocentric view until Isaac Newton, in 1687, formulated the Law of Universal Gravitation. This law explained how gravity would cause the planets to orbit the much more massive Sun and why the small moons around Jupiter and Earth orbited their home planets. How long did it take for Copernicus’s ideas to reach the general public? Does anyone nowadays still believe the apparent evidence before their eyes that the Sun moves around the Earth to set and rise? Almost everyone learns in childhood that, despite appearances, the Earth moves around the Sun. Copernicus’s model asked people to give up thinking that they lived in the center of the Universe. For him the thought of the Sun illuminating all of the planets as they rotated around it had a sense of great beauty and simplicity. For further discussion Think about the following question and write your response and any additional questions you have in the Questions Area below. This article summarizes Copernicus’s theories in four points. Were his theories correct? [Sources and attributions] |
Standing on the Shoulders of Invisible Giants By Eman M. Elshaikh The history of science is a history of our collective learning. Historians piece together different conversations to tell a story that crosses centuries and continents Sir Isaac Newton, the famous English scientist, once said, “If I have seen further, it is by standing on the shoulders of giants.” Of course, Newton wasn’t literally standing on the shoulders of giants. Newton was explaining that his ideas didn’t come from him alone. He relied on the ideas of those who came before him. When Newton used the word giant, he meant people who were giants in the scientific community. These were the people who, before him, made big contributions to our knowledge. Newton, even though he was a genius himself, knew that he couldn’t have come up with his scientific breakthroughs on his own. That’s probably not a surprise to you. But what you might not know is that some of those giants came from the Islamic world. And that might be surprising because Newton was a European scientist. The Renaissance—and the Scientific Revolution, which came later—started in Europe, so many assume that’s where all the scientists were. But many of the ideas that developed in Europe during the Scientific Revolution in the sixteenth and seventeenth centuries were influenced by the work of earlier scholars in the Islamic world and elsewhere. We often hear about the medieval period as a “dark age,” but that’s not quite accurate. From the eighth to the thirteenth century, a golden age of culture and scientific thinking flourished in the Islamic world, which stretched from the Iberian Peninsula (Spain and Portugal) to India. Of course, these scholars also stood on the shoulders of giants from Greece, India, and China. Yet despite the giant innovations of Islamic scholars, they have often been left out of the story, making them invisible. So let’s look a little closer at what these “invisible giants” can show us. Collective learning When Newton spoke of standing on the shoulders of giants, he was talking about collective learning—our species’ unique ability to share, preserve, and build upon knowledge over time. It’s a key part of what makes us human. Our creative abilities depend on learning from the work of others—just like Newton did. You rely on collective learning when you learn by reading a book or listening to your teacher. When you use these ideas in a school project, you make your own contribution to collective learning by sharing your ideas with others. In that way, you become a part of the chain of collective learning. Sometimes it’s easy to see how collective learning moves from one thinker to another, or one community to another. For example, we know that the great astronomer Nicolaus Copernicus directly influenced two other famous astronomers: Galileo Galilei and Johannes Kepler. If we think of Copernicus as a giant, we can say that Galileo and Kepler stood on his shoulders to reach greater heights. And our friend Newton stood on their shoulders to reach even higher. These thinkers lived in different times and places, but we can imagine collective learning as a kind of conversation they had across time and distance. They might never have met, but the transfer of their ideas across time and space allowed science theories to be built, questioned, and refined. These conversations aren’t exactly easy to spot. Historians of science have to work hard to find the evidence that connects one thinker to another. We know about some of these links because historians pieced together the story from a variety of documents. One of the things that makes this so hard is that these documents are located in different countries and written in different languages. Some are better preserved than others. Collecting and translating is already a big challenge, but then historians must put them together and make arguments. These documents are sometimes incomplete or missing, which makes the job even harder. And in many cases, historians just haven’t gotten around to reading them yet. There are thousands of manuscripts that historians are still reading and analyzing so they can uncover stories about the history of science still waiting to be told! The further you go back in time, the harder it is. Copernicus and Newton weren’t separated by that much time or distance, at least compared to the wide separation of Copernicus from Islamic scholars like the Persian astronomer Nasir al-Din al-Tusi, who lived centuries before Copernicus and thousands of miles away! Collective learning is like a conversation that happens across time and space. Over millennia and across continents, humans have contributed to our collective knowledge by writing, publishing, talking, teaching, analyzing, debating, collaborating, and sharing ideas. © DrAfter123 / DigitalVision / Getty Images. We have to wonder: how many invisible giants are still out there? How will we discover them? Which scholars have had their contributions to science erased by time and distance? Probably quite a few. There are a lot of reasons they don’t appear in the historical record. They might be “invisible” because historians just don’t know much about them yet. Even if historians do know about them, they may debate who influenced whom and how much of an influence there really was. Unlike students and scholars today, who carefully write down their sources and references, scientists in the past didn’t always do this. Scientists often borrowed the ideas of others without giving them credit directly. So, historians must connect the dots in other ways. One way is by noticing similarities between two scientists’ work, and then researching how a scientist in one place might have influenced another scientist who lived very far away in a different time. You know that story of Newton discovering gravity by watching an apple fall? That’s called an “aha! moment” and stories of scientific geniuses are full of them. But there is a lot more to collective learning than aha! moments. Adaptations, conversations, arguments, and changes are what keep the scientific conversation going, century after century. Yes, it includes Newton, Copernicus, and al-Tusi, but also included are students and teachers, librarians and writers, historians and astronomers, and you! A bigger history of science To really think about collective learning, we have to tell bigger stories that include once-invisible giants. While Copernicus influenced many scientists, we have to ask: who influenced Copernicus? On whose shoulders did he stand? Copernicus is said to have started the Scientific Revolution, but was there no science before him? Some historians say, “Of course there was—in Europe, China, India, the Islamic world, and beyond!” Historians of science today are beginning to uncover many of these connections. For example, some think Copernicus was influenced by Persian astronomers like al-Tusi. For that matter, al-Tusi was influenced by Chinese and ancient Greek astronomers. Plus, al-Tusi couldn’t have done his mathematical calculations without Arabic numerals—which are really based on a numbering system developed in ancient India. And—oh, wait!—those were introduced earlier by the Persian mathematician al-Khwarizmi. These connections are part of our Big History, because they add to our collective learning. It happens across continents and across centuries. Throughout this course, you’ll learn about important moments in our collective learning. You might wonder why you haven’t heard about these scholars before. Well, it’s still a pretty new field of history! Historians of science continue to learn, debate, and write about it. They argue over who the giants are and how their ideas traveled. Our collective learning about the topic is still growing—and we learn new things every day. It’s a complicated story, but it’s definitely worth telling, especially when it has the power to make invisible giants more visible Author bio Eman M. Elshaikh holds an MA in social sciences from and is pursuing a PhD at the University of Chicago, where she also teaches writing. She is a writer and researcher, and has taught K-12 and undergraduates in the US and in the Middle East. Eman was previously a World History Fellow at Khan Academy, where she worked closely with the College Board to develop curriculum for AP world history. [Sources and attributions] |
Measuring Distance in the Universe By Cynthia Stokes Brown Born: July 4, 1868; Lancaster, Massachusetts. Died: December 12, 1921; Cambridge, Massachusetts. Henrietta Leavitt © Photo Researchers Henrietta Leavitt discovered the relationship between the intrinsic brightness of a variable star and the time it took to vary in brightness, making it possible for others to estimate the distance of these faraway stars, conclude that additional galaxies exist, and begin mapping the Universe. Early life and education Henrietta Swan Leavitt was a minister’s daughter whose family moved frequently. When she was about 14, the family moved to Cleveland, Ohio, and in 1885 Leavitt enrolled in Oberlin College to prepare for the strict entrance requirements of the college she really wanted to attend — the Society for Collegiate Instruction of Women, later known as Radcliffe College (now part of Harvard University), in Cambridge, Massachusetts – a dream she achieved at age 20. She discovered her calling in her senior year when she took a course in astronomy. At the Harvard College Observatory Leavitt liked astronomy so much that after graduation she became a volunteer at the Harvard College Observatory as a “computer.” This was the name used for women who examined tiny dots on time-exposed photographs of the night sky and then measured, calculated, and recorded their observations in ledger books. Eventually, in 1902, Leavitt was hired at 30 cents an hour; she continued to work at the observatory for the remaining 19 years of her life. Leavitt took a special interest in the Magellanic Clouds, a pair of luminous hazes now known to be irregular galaxies, the nearest ones to our Milky Way. At the time, no one knew what the clouds were. Since the Magellanic Clouds are only visible in the southern hemisphere, Leavitt could not see them directly. She could merely look at photographic plates taken at Harvard’s auxiliary observatory, in Arequipa, Peru, and sent to Cambridge by ship around the tip of South America. Using Cepheid variables One of Leavitt’s jobs was to examine the variable stars, which, unlike most stars, vary in brightness because of fluctuations within themselves. In the course of her work, Leavitt discovered 2,400 new variable stars, half the known ones in her day. A certain group of variable stars, later called Cepheid variables, fluctuate in brightness (luminosity) in a regular pattern called their “period.” This period ranges from about one day to nearly four months. By comparing thousands of photographic plates, Leavitt discovered a direct correlation between the time it takes for a Cepheid variable to go from bright to dim and back to bright, and how bright the star actually is (its “intrinsic brightness”). The longer the period of fluctuation, the brighter the star. This meant that even though a star might appear extremely dim, if it had a long period it must actually be extremely large; it appeared dim only because it was extremely far away. By calculating how bright it appeared from Earth and comparing this to its intrinsic brightness, one could estimate how much of the star’s light had been lost while reaching Earth, and how far away the star actually was. Leavitt published her first paper on the period-luminosity correlation in 1908. Four years after that, she published a table of the periods of 25 Cepheid variables. Nine years later, in 1921, she died of cancer at age 53 in Cambridge. Timeline of Leavitt's life. Click here for a larger version. Download PDF. Leavitt’s Legacy Before Leavitt established the period-luminosity relationship, astronomers could determine cosmic distances out only about 100 light years. Using her insights, astronomers were able to estimate the Magellanic Clouds to be in the range of 100,000 light years from Earth — much further than anyone had imagined — meaning they could not be within the Milky Way galaxy. The largest telescope then in existence opened in 1904 at Mount Wilson, near Los Angeles, California. In 1919, the astronomer Edwin Hubble took a job there, after finishing his PhD in astronomy at the University of Chicago. Using the Mount Wilson telescope and building on Leavitt’s work, Hubble located Cepheid variables so far away that they conclusively established the presence of other galaxies. By 1925, most astronomers agreed that our galaxy is one among a multitude — a small outpost in a Universe full of galaxies. Leavitt initially worked under a director of the Harvard College Observatory who did not encourage theorizing but preferred only to accumulate data. A later director even tried to take some of the credit for her work after her death. Now, however, Leavitt is recognized as a key contributor to our understanding of the size of the Universe. A modest life Leavitt never married. She gradually became deaf, starting with an illness when she was a young adult. She was buried in Cambridge in the family plot, near the graves of Henry and William James. Her total estate was appraised at $314.91. In her obituary, a senior colleague wrote: “[She] was possessed of a nature so full of sunshine that, to her, all of life became beautified and full of meaning.” [Sources and attributions] |
The Graphic Biography below uses “Three Close Reads”. If you want to learn more about this strategy, click here. Reading 1: Skimming for gist This will be your quickest read. It should help you get the general idea of what the graphic biography will be about. Pay attention to the title, headings, images, and layout. Ask yourself: what is this graphic biography going to be about? Reading 2: Understanding content For this reading, you should be looking for unfamiliar vocabulary words, the major claim and key supporting details, and analysis and evidence. You should also spend some time looking at the images and the way in which the page is designed. By the end of the second close read, you should be able to answer the following questions: What does the portion of the comic involving bathroom doors tell you about Vera's experience as a scientist?What does the comic mean by saying the Vera's most important observation was something we can't see?What evidence did Vera use to uncover the existence of dark matter?What does Vera mean in the quote at the top of the page: "We're out of kindergarten, but only in about third grade"?How was the artist designed the page, text, and illustrations to tell you about Vera's observations and career? What does the portion of the comic involving bathroom doors tell you about Vera's experience as a scientist? What does the comic mean by saying the Vera's most important observation was something we can't see? What evidence did Vera use to uncover the existence of dark matter? What does Vera mean in the quote at the top of the page: "We're out of kindergarten, but only in about third grade"? How was the artist designed the page, text, and illustrations to tell you about Vera's observations and career? Reading 3: Evaluating and Corroborating In this read, you should use the graphic biography as evidence to support, extend, or challenge claims made in the course. At the end of the third read, you should be able to respond to these questions: What does this biography tell you about how our understanding of the Universe has changed? How did perceptions of Vera's observations change over time? Now that you know what to look for, it’s time to read! Remember to return to these questions once you’ve finished reading. Revealing the Dark: Vera Rubin (Graphic Biography) Writer: Bennett Sherry Artist: Kay Sohini Vera Rubin’s observations revealed that our Universe is largely composed of matter we cannot see. Her work was met with skepticism, but she transformed astronomy. Download the Graphic Biography PDF here or click on the image above. |
All of the following terms appear in this unit. The terms are arranged here in alphabetical order. astronomy — The branch of science that deals with the Universe and the various objects, like stars, planets, and galaxies, that we find within it. Cosmology and astrophysics are closely related to astronomy, and the words are sometimes used interchangeably. Cosmology focuses on the Universe’s largest scales in space and time, and astrophysics focuses on the properties and interactions of astronomical objects. atom — A small unit of matter composed of protons, electrons, and usually neutrons. Atoms are basic building blocks of the matter we see in the Universe and on Earth. The number of protons in the nucleus of an atom determines which chemical element it is. authority — A respectable or credible source; an expert. Big Bang — A theory, first articulated in the 1920s, proposing that the Universe started out extremely hot and dense and gradually cooled off as it expanded. Cepheid — A star that fluctuates in brightness and provides astronomers with a reference they can use to measure great distances in the Universe. It was the identification of Cepheids in nearby galaxies that first proved that the Universe consists of more than one galaxy. claim — An assertion that something is true. claim testing — The use of strategies to decide whether a story or concept should or should not be trusted. The four strategies for claim testing that we use in Big History are intuition, authority, logic, and evidence. collective learning — The ability to share, preserve, and build upon ideas over time. Cosmic Microwave Background (CMB) or Cosmic Background Radiation (CBR) — Low-energy radiation pervading the entire Universe, released about 380,000 years after the Big Bang. At this point, the Universe had cooled sufficiently for atoms to form and allow radiation and matter to separate. cosmology — The study of the Universe on its largest scales, including its origin and structure. Doppler effect — The apparent stretching out or contraction of waves because of the relative movement of two bodies. The Doppler effect explains why an ambulance siren seems higher when the ambulance is traveling toward you than when it is moving away. It also helps astronomers identify whether objects such as stars or galaxies are moving toward us or away from us. electromagnetism — One of the four fundamental forces or interactions, along with gravity, the weak nuclear force, and the strong nuclear force. Among other things, electromagnetism is responsible for the interaction between electrically charged particles, including holding electrons and protons together to form atoms. Electromagnetism is also responsible for essentially all molecular interactions. electron — A negatively charged subatomic particle that orbits the nucleus of an atom. energy — The capacity to do work, associated with matter and radiation. Includes kinetic energy, potential energy, and chemical energy, among others. evidence — Concrete, verifiable information that either supports or disproves a claim. gravity — The fundamental force of attraction between any two objects that have mass. helium — The second simplest of all chemical elements, helium has two protons and (almost always) two neutrons. Helium was produced soon after the Big Bang. hydrogen — The simplest of all chemical elements, hydrogen has one proton. Hydrogen was the first element produced after the Big Bang and is the most common element in the Universe. inflation — The idea that space and time (space-time) underwent an expansion at a rate much faster than the speed of light during the first 10-36 seconds after the Big Bang. intuition — A “gut feeling” that is not necessarily based on logic or evidence. light-year — A measure of distance in space; the distance that light travels in a vacuum in one year. It is equal to roughly 9.5 trillion kilometers, or 5.9 trillion miles. logic — The application of systematic reasoning to arrive at a conclusion. matter — The physical material of the Universe, including subatomic particles, atoms, and the substances that are built out of them. neutron — An electrically neutral subatomic particle present in the nuclei of most atoms. Unlike protons, the number of neutrons in a given element can vary, giving rise to different isotopes of an element. nucleus (atomic) — The extremely dense and positively-charged region at the center of an atom that consists of protons and neutrons. parallax — The change in the apparent position of an object caused by movement of the observer. proton — A subatomic particle with a positive electric charge. The number of protons in an atom (the atomic number) determines which element it is: For example, carbon atoms always have 6 protons, while iron atoms always have 26 protons. redshift — The phenomenon in which light waves from distant galaxies are “stretched out,” which for visible light means a shift toward the red side of the spectrum. Redshift provides scientists with strong evidence that the Universe is expanding, since the expansion of space explains the stretching of the light waves. scientific method — The process of gathering evidence to test and refine scientific theories. space-time — The unification of space and time into a single four-dimensional continuum or “fabric.” Space makes up three of the dimensions, while time makes up the fourth, and cannot be fully separated from space. Albert Einstein’s General Theory of Relativity holds that all objects with mass interact with space-time by bending it much like a person standing on a trampoline bends the trampoline. telescope — An instrument used for viewing distant objects, including planets, stars, and galaxies. thermodynamics (first law of) — One form of the law of conservation of energy, which states that energy may change forms but cannot be created or destroyed. |
Browse through different views of the Universe and zoom in on the light from distant stars to better understand how our understanding of cosmology has evolved. Ptolemy's Universe Source: Big History ProjectThe Ptolemaic view of the Universe was an Earth-centered, or geocentric, model. The Sun and all of the planets orbited the Earth and the other stars formed a backdrop that also orbited Earth. Source: Big History Project The Copernican Model The idea of a Sun-centered, or heliocentric, view of the Universe had been suggested by ancient Greek astronomers like Aristarchos and was later published by Polish astronomer Nicolaus Copernicus in 1543. To some extent, this model (not at actual scale in this illustration) ushered in a new age of astronomy. Kepler and Elliptical Orbits The German astronomer and mathematician Johannes Kepler demonstrated that the orbits of Earth and the other planets (not drawn to scale in this illustration) were not perfectly circular but were actually elliptical, or egg-shaped. Redshift This illustration simulates the redshift, or Doppler shift, that affects how light waves appear to us when the source of light is moving away. When we view galaxies from Earth, their light is shifted to the red side of the color spectrum, an indication that they are moving away from us. This is strong evidence for an expanding Universe. The Electromagnetic Spectrum It's important to remember that what we see as visible light is only a small portion of the full electromagnetic spectrum. Many modern telescopes are able to view different wavelengths of electromagnetic energy, thus generating images from space that are completely invisible to the unaided eye. Spectral Lines The color of light from objects in space can be used for more than gauging distances. Different elements actually leave their own "signatures" in light. Scientists can use spectral lines to determine the chemical composition of objects in space like other stars and planets. Hydrogen, helium, and oxygen are the three most abundant elements in the Universe. Cepheid Variable Star V1 in the Andromeda Galaxy Source: NASA, ESA, the Hubble Heritage Team Astronomers use the fluctuating brightness of Cepheid variable stars like V1 as "stellar yardsticks" to measure distances. The discovery of Cepheids and the understanding of how to interpret their fluctuations of brightness helped prove that the Universe was a much larger place than first thought. Cepheids in the Galaxy NGC 5584 Source: NASA, ESA, L. Frattare (STScl), A. Riess (STScl/JHU) and L. Macri (Texas A & M University) This illustration shows the location of the many Cepheid variable stars found in the spiral galaxy NGC 5584. Different Cepheids have different "periods" related to the total energy they put out as they burn hydrogen and helium. The Horn Antenna Source: NASA The Horn reflector antenna at Bell Telephone Laboratories in Holmdel, New Jersey was built in 1959 and became famous when Arno Penzias and Robert Wilson used it to detect the Cosmic Microwave Background (CMB), the afterglow of the Big Bang. In 1989 The Horn was dedicated to the U.S. National Park Service as a National Historic Landmark. The Cosmic Microwave Background Source: NASA/WMAP Science Team These details of the CMB were captured by NASA's Wilkinson Microwave Anistropy Probe (WMAP) at the very start of the 21st century. The color-enhanced WMAP imagery of the infant Universe shows the slight variations in temperature that correspond to the slight variations in density that helped seed the formation of the first galaxies. |
The Missing Link? The Maragha Observatory By Eman M. Elshaikh From Ptolemy to Copernicus and Galileo, thinkers have debated what the Universe looked like for centuries. Ultimately, scholars moved from an Earth-centered model to a Sun-centered model. How did we get there? Planetary revolutions Television with breaking news is a composite image of the Earth orbiting the Sun, Breaking News lower thirds banner, and television, all via Freepik. Or at least it was big news to people living in the sixteenth century, when this revolutionary idea challenged people’s understanding of the Universe. Ancient astronomers like Ptolemy (100–170 CE) believed that the Earth was at the center of the Universe. They thought the Sun, stars, and planets revolved around Earth. This belief persisted—although some questioned it—for many hundreds of years. By the sixteenth century, however, astronomers like Copernicus (1473–1543 CE) and Galileo (1564–1642 CE), started challenging Ptolemy’s model. They put the Sun at the center. This heliocentric (Sun at the center) model of the Universe shocked people at the time. The Catholic Church even jailed Galileo for claiming it. Like all scholars, Copernicus and Galileo came up with their ideas using the knowledge of those who came before them. What was this earlier knowledge? About 1,400 years separated Copernicus from Ptolemy. But we don’t hear much about the people who came between—who carried on the collective learning conversation between these major figures. For centuries, scholars had been slowly chipping away at the Earth-at-the-center model. The tenth-century Arab astronomer, Ibn al-Haytham (965–1040 CE), for example, questioned Ptolemy’s model. He pointed out several contradictions and claimed that Ptolemy’s idea about how different planets fit together simply didn’t work. An even earlier Arab astronomer, al-Battani (858–929 CE), calculated the movement of the Sun and the planets. His carefully recorded observations were cited by Copernicus many times. So while Copernicus is famous for challenging Ptolemy, there have been missing links in history’s centuries-long chain of thinkers who contributed to this debate. Thanks to the work of many invisible giants like Ibn al-Haytham and al-Battani, it was possible for scholars who came later to construct a serious challenge to such a long-accepted view of the Universe. Many of these invisible giants were astronomers working during the Golden Age of Islam. A golden age during a dark age The scholars between Ptolemy and Copernicus were part of a vibrant tradition of astronomy in the Islamic world. These scholars were supported largely by the wealthy rulers of Islamic empires, and together their work launched a period of scientific and cultural achievement called the Islamic Golden Age. By building on the knowledge of Greek, Indian, Chinese, Babylonian, Persian, and Arab thinkers before them, scholars were able to make new observations and discoveries. Astronomy was a major field for these scholars. For Muslims of this period, astronomy was a practical science that was important for religious practice. By measuring the movement of the Sun, Moon, and stars, Muslim scientists determined the times for daily prayers, set the dates for the lunar calendar, and precisely calculated the direction of Mecca from any location. This knowledge was valuable to Muslim political and religious leaders. As a result, many Muslim rulers built observatories—special buildings for studying astronomy. Among the most famous and important of these was the Maragha Observatory. There, scholars seriously challenged Ptolemy’s Earth-at-the-center system, which had been accepted for many centuries. The geocentric or Earth-centered model of the Universe, which places the Earth at the center of planetary orbits. Ptolemy was one thinker who proposed this model, which was accepted for centuries after Ptolemy’s death. By BHP and Peter Quatch, CC BY-NC 4. The heliocentric or Sun-centered model of the Universe, which places the Sun at the center of planetary orbits. Copernicus was arguably the first scholar to propose this model. By BHP and Peter Quatch, CC BY-NC 4.0. The Maragha Observatory In the thirteenth century, the Mongol ruler Hulagu Khan conquered a big part of the Islamic world. After founding the Ilkhanate of Persia, he destroyed the city of Baghdad, along with the many books in its famed House of Wisdom. Despite the Mongols’ destruction of scientific knowledge in this unfortunate case, they also supported its creation. Like the Arab and Persian rulers who came before them, Mongol rulers supported scholars, especially astronomers. In addition to the practical importance of astronomy to Islam, Mongol rulers believed that studying the stars would help them make decisions and predict the future, so they brought astronomers from across their massive empire to their courts. Once he had finished his wars of conquest, Hulagu Khan worked with the great Persian astronomer Nasir al-Din al-Tusi, and built the Maragha Observatory in Persia. It was the most advanced observatory in the world at the time. It attracted astronomers from across the Islamic world and from as far away as China. Under Mongol rule, astronomers from across Eurasia shared ideas, which sped up new developments in collective learning. Maragha astronomers recorded their astronomical observations and calculations in the massive library at the observatory. Using these observations, they came up with new ideas about how the planets moved. One of the most important of these new ideas was called the “Tusi couple,” named after Nasir al-Din al-Tusi many centuries later. The Tusi couple may sound like the screen name of a pair of adorable lovebirds on Instagram, but it’s actually a mathematical idea. Astronomers used the Tusi couple to create models of a small circle rotating within a larger one, and then track the motion of the rotation. It helped astronomers understand how different celestial bodies revolve around one another. Ibn al-Shatir, a Syrian astronomer, built on this work. Using the Tusi couple, Ibn al-Shatir corrected Ptolemy’s calculations about distances between planetary bodies. Ibn al-Shatir wanted to create a model of the Solar System that fit with the observations he and others had made. His model was much more accurate than Ptolemy’s. While the models coming out of the Maragha Observatory kept the Earth at the center, they made crucial changes to Ptolemy’s model and moved our collective understanding closer to a Sun-centered model. The missing link? Neither Nasir al-Din al-Tusi nor Ibn al-Shatir understood the Sun was at the center of the Solar System. Still, their work may have provided the foundation for Copernicus’s heliocentric model. OK, words like “may have” are frustrating when you want to know if something is true, but not all historians agree on this. The “conversations” among Copernicus, Ptolemy, and the Maragha scholars were spread out over 14 centuries. It’s hard to prove how these ideas developed, moved, or changed, but it’s still important to look for connections. On the one hand, some historians of science argue that scholars like al-Tusi and Ibn al-Shatir influenced Copernicus’s heliocentric system. They use this evidence to support their claims: The work of these scholars had been translated and spread around Eurasia for centuries before Copernicus’s time. It’s logical to assume that an educated man like Copernicus would have come across their work.There are similarities between Copernicus’s diagrams and mathematical arguments and those of the Maragha scholars. Some of Copernicus’s models of planetary rotations used mathematical ideas that were nearly identical to the Tusi couple. Some historians even argue that the diagrams are labeled similarly to Ibn al-Shatir’s.Without this link, it’s more difficult to explain how Copernicus made the leaps that led to his conclusion that the Sun is at the center of our Solar System. The work of these scholars had been translated and spread around Eurasia for centuries before Copernicus’s time. It’s logical to assume that an educated man like Copernicus would have come across their work. There are similarities between Copernicus’s diagrams and mathematical arguments and those of the Maragha scholars. Some of Copernicus’s models of planetary rotations used mathematical ideas that were nearly identical to the Tusi couple. Some historians even argue that the diagrams are labeled similarly to Ibn al-Shatir’s. Without this link, it’s more difficult to explain how Copernicus made the leaps that led to his conclusion that the Sun is at the center of our Solar System. On the other hand, other historians disagree. They don’t think the Maragha Observatory scholars influenced Copernicus’s heliocentric system. They use this evidence to support their claims: While Copernicus cited scholars like al-Battani, he never mentioned al-Tusi or Ibn al-Shatir. (Of course, scientists of this era often borrowed freely from one another and reworked each other’s ideas without giving direct credit.)These Islamic scholars didn’t have a heliocentric model. In fact, their models are pretty different from Copernicus’s.There may be similarities in mathematical ideas, but these mathematical ideas are used very differently.Even if there are some similarities, these historians argue that it’s possible to have similarity without direct influence. They could be independent discoveries. While Copernicus cited scholars like al-Battani, he never mentioned al-Tusi or Ibn al-Shatir. (Of course, scientists of this era often borrowed freely from one another and reworked each other’s ideas without giving direct credit.) These Islamic scholars didn’t have a heliocentric model. In fact, their models are pretty different from Copernicus’s. There may be similarities in mathematical ideas, but these mathematical ideas are used very differently. Even if there are some similarities, these historians argue that it’s possible to have similarity without direct influence. They could be independent discoveries. Historians will continue to debate these questions. You might say that historians are still learning about collective learning. Who learns it? Who collects it? How, over thousands of years, is knowledge shared, moved, changed, translated, improved, and challenged? No matter how historians answer these questions, it’s important to keep revealing the influence of invisible giants like Ibn al-Haytham, al-Battani, al-Tusi, Ibn al-Shatir, and many others. Only then can we start to make connections that allow us to tell our Big History more fully. Author bio Eman M. Elshaikh holds an MA in social sciences from and is pursuing a PhD at the University of Chicago, where she also teaches writing. She is a writer and researcher, and has taught K-12 and undergraduates in the US and in the Middle East. Eman was previously a World History Fellow at Khan Academy, where she worked closely with the College Board to develop curriculum for AP world history. [Sources and attributions] |
An Earth-Centered View of the Universe Born: 85 CE; Hermiou, Egypt. Died: 165 CE; Alexandria, Egypt. Portrait of Ptolemy by Andre Thevet © Bettmann/CORBIS By Cynthia Stokes Brown The Earth was the center of the Universe according to Claudius Ptolemy, whose view of the cosmos persisted for 1400 years until it was overturned — with controversy — by findings from Copernicus, Galileo, and Newton. An Astronomer in Ancient Times Claudius Ptolemy (about 85–165 CE) lived in Alexandria, Egypt, a city established by Alexander the Great some 400 years before Ptolemy’s birth. Under its Greek rulers, Alexandria cultivated a famous library that attracted many scholars from Greece, and its school for astronomers received generous patronage. After the Romans conquered Egypt in 30 BCE (when Octavian defeated Cleopatra), Alexandria became the second-largest city in the Roman Empire and a major source of Rome’s grain, but less funding was provided for scientific study of the stars. Ptolemy was the only great astronomer of Roman Alexandria. Ptolemy was also a mathematician, geographer, and astrologer. Befitting his diverse intellectual pursuits, he had a motley cultural makeup: he lived in Egypt, wrote in Greek, and bore a Roman first name, Claudius, indicating he was a Roman citizen — probably a gift from the Roman emperor to one of Ptolemy’s ancestors. A Geocentric View Ptolemy synthesized Greek knowledge of the known Universe. His work enabled astronomers to make accurate predictions of planetary positions and solar and lunar eclipses, promoting acceptance of his view of the cosmos in the Byzantine and Islamic worlds and throughout Europe for more than 1400 years. Ptolemy accepted Aristotle’s idea that the Sun and the planets revolve around a spherical Earth, a geocentric view. Ptolemy developed this idea through observation and in mathematical detail. In doing so, he rejected the hypothesis of Aristarchus of Samos, who came to Alexandria about 350 years before Ptolemy was born. Aristarchus had made the claim that the Earth revolves around the Sun, but he couldn’t produce any evidence to back it up. Map of the Universe according to Ptolemy, from a 17th century Dutch atlas by Gerard Valck © Bettmann/CORBIS Based on observations he made with his naked eye, Ptolemy saw the Universe as a set of nested, transparent spheres, with Earth in the center. He posited that the Moon, Mercury, Venus, and the Sun all revolved around Earth. Beyond the Sun, he thought, sat Mars, Jupiter and Saturn, the only other planets known at the time (as they were visible to the naked eye). Beyond Saturn lay a final sphere — with all the stars fixed to it — that revolved around the other spheres. This idea of the Universe did not fit exactly with all of Ptolemy’s observations. He was aware that the size, motion, and brightness of the planets varied. So he incorporated Hipparchus’s notion of epicycles, put forth a few centuries earlier, to work out his calculations. Epicycles were small circular orbits around imaginary centers on which the planets were said to move while making a revolution around the Earth. By using Ptolemy’s tables, astronomers could accurately predict eclipses and the positions of planets. Because real visible events in the sky seemed to confirm the truth of Ptolemy’s views, his ideas were accepted for centuries until the Polish astronomer, Copernicus, proposed in 1543 that the Sun, rather than the Earth, belonged in the center. After the Roman Empire dissolved, Muslim Arabs conquered Egypt in 641 CE. Muslim scholars mostly accepted Ptolemy’s astronomy. They referred to him as Batlamyus and called his book on astronomy al-Magisti, or “The Greatest.” Islamic astronomers corrected some of Ptolemy’s errors and made other advances, but they did not make the leap to a heliocentric (Sun-centered) universe. Ptolemy’s book was translated into Latin in the 12th century and known as The Almagest, from the Arabic name. This enabled his teachings to be spread throughout Western Europe. We know few details of Ptolemy’s life. But he left one personal poem, inserted right after the table of contents in The Almagest: Well do I know that I am mortal, a creature of one day.But if my mind follows the wandering path of starsThen my feet no longer rest on earth, but standing byZeus himself, I take my fill of ambrosia, the food of the gods. For Further Discussion Think about the following question and write your response and any additional questions you have in the Questions Area below. Even though Ptolemy’s system was wrong, people believed in it. Why? [Sources and attributions] |
Father of Modern Observational Astronomy By Cynthia Stokes Brown Born: February 15, 1564; Pisa, Italy. Died: January 9, 1642; Florence, Italy. An undated portrait of Galileo © Bettmann/CORBIS An Italian Renaissance man, Galileo used a telescope of his own invention to collect evidence that supported a Sun-centered model of the Solar System. Youth and Education Galileo Galilei was born in Pisa, Italy, on February 15, 1564, the first of seven children of Vincenzo Galilei and Giulia Ammanati. Galileo’s father was a musician — a lute player — from a noble background that conferred on him the right to hold civic office in the Duchy of Florence, which in 1569 became the Grand Duchy of Tuscany. At the time, Italy was made up of small territories ruled by hereditary dukes. When Galileo was 10, his family moved to Florence, northeast of Rome, where he was educated in a monastery. He was attracted to the priesthood, but his father steered him to study medicine from 1581 to 1585 at the University of Pisa, some 40 miles west of Florence on the coast, and very near Galileo’s childhood home. University studies at that time were based primarily on Aristotle’s philosophy, but Galileo’s acute observations caused him to question some of these accepted views. He noticed that hailstones of different sizes reached the ground simultaneously, contradicting Aristotle’s rule that bodies fall with speeds proportional to their size. At this time Galileo also sat in on lectures by a practical mathematician in the service of the Grand Duke, apart from his university studies. Professor at Pisa and Padua After four years at university Galileo gave private lessons in mathematics and wrote his first scientific paper, about how things float on water. In 1587 he got a position teaching mathematics at the University of Pisa, which paid him a very modest salary. Two years later Galileo’s father died, leaving Galileo responsible for the promised dowries of his two sisters. The next year he secured the chair of mathematics at the renowned University of Padua, and the new position paid three times as much. In addition to mathematics, Galileo gave private instruction in military architecture, fortification, surveying, and mechanics. At the age of 31 Galileo showed his first interest in astronomy, while working to explain the cause of the tides. (Padua was 20 miles inland from Venice, an important trading port on the Adriatic Sea.) Astronomy was considered part of mathematics at the time, while cosmology was part of philosophy. Most scholars still held the views of Ptolemy, who followed Aristotle in thinking that all heavenly bodies revolve around Earth (a geocentric model). But other views were being considered, including that of Copernicus, who claimed that all bodies revolve around the Sun (a heliocentric model), and of Danish astronomer Tycho Brahe, who held that Earth was fixed but other planets are in orbit around the Sun. In 1597 a German visitor gave Galileo a book by German astronomer Johannes Kepler, who was enthusiastically pro-Copernicus. Galileo wrote a letter to Kepler stating that he had long agreed with Copernicus but that he had not dared to make his thoughts public because he was frightened that he would become, like Copernicus, “mocked and hooted by an infinite multitude.” In the same year Galileo invented a mechanical device for mathematical calculations. He had a craftsman make them, so that Galileo could sell them and give classes on how to use them. Professors at Padua tended not to marry, and prominent families there did not view Galileo as a catch. Instead, Galileo established a lasting relationship with a non-noble woman 14 years younger, Marina Gamba, and had three children with her. He never married her, and she and the children lived separately, around the corner from him. When he later left Padua in 1610 to move to Florence, he put their two daughters in a convent as soon as possible, and he left his son, Vincenzo, in Padua in Marina’s care. Galileo’s first known astronomical observation occurred in 1604, when a supernova (the explosive death of a high mass star) was visible in the sky. Such an event clearly challenged Aristotle’s claim that no change could ever take place in the heavens. From then on, observation and experimentation became the basis for Galileo’s work. Galileo’s prominence as a mathematician and scholar grew, and in the summer of 1605 he arranged to tutor Cosimo de Medici, the son of the Grand Duke of Tuscany. In July 1609 Galileo heard about a Dutch device for making distant objects look nearer. A friend who saw it described it to Galileo as having two lenses, one on each end of a four-foot tube. Within about a month Galileo had made an instrument three times as powerful as the Dutch device. Galileo continued to work on his telescope, grinding his own lenses. By December 1609 he had seen for the first time the four largest moons orbiting around Jupiter, which contradicted Ptolemaic theory that Earth is the center of all orbiting bodies. Galileo published his findings in March 1610 as The Starry Messenger; the general public was excited, but most philosophers and astronomers declared it an optical illusion. An engraving of Galileo with his telescope © Mary Evans / PhotoResearchers, Inc Mathematics at the Court of Tuscany Galileo was offered life tenure at the University of Padua, but Florence was his home, and he wanted freedom from teaching. So he took the job of court mathematician in Florence, where his former math student had become Cosimo II, the Grand Duke of Tuscany. Soon after his arrival in Florence in September 1610, Galileo began his observations of Venus. Over time he discovered that the Moon-like phases of Venus demonstrated that the neighboring planet had an orbit independent of Earth. This showed conclusively that Venus circled the Sun, as Copernicus thought, not Earth, as Ptolemy thought. But it did not yet prove conclusively that Earth circled the Sun. In 1613 Galileo published his Letters on Sunspots, based on his observations of the dark spots on the Sun that are caused by intense magnetic activity. In an appendix he noted that he agreed with Copernicus, mentioning the fact that he had seen eclipses of the satellites of Jupiter, further evidence that they orbited the planet. This is the only time that Galileo expressed in print his support of the Copernican model. Galileo had no definitive evidence that Copernicus was right, and he didn’t claim that he did. Galileo’s main pieces of evidence were the phases of Venus, the eclipses of Jupiter’s moons, the existence of tides (which Galileo believed could only occur if the Earth moved), observable planetary speeds, and the distances of planets from the Sun. Drama with the Inquisition During the first part of the 16th century the Catholic Church was facing the challenge of Protestants, who were breaking away from the Catholic Church over certain doctrines. By this time there were printers in many European cities and ideas were spreading quickly, some of them in opposition to the Catholic Church and its beliefs. To combat all heresies, the Pope set up a system of tribunals, or courts, called the Inquisition. In 1616, the year of Shakespeare’s death, the authorities of the Inquisition in Rome decided to prohibit Copernicus’s book, On the Revolutions of the Celestial Spheres, and any other books that argued in favor of a Copernican Sun-centered model for the Solar System. Galileo traveled to Rome to try to prevent this; he thought it was a mistake that would eventually tarnish the church’s reputation. He believed that the Catholic Church should keep science and religion completely separate and not interfere with scientific research. The Church upheld their position and Galileo agreed to obey the ban. In 1623 a Florentine who admired Galileo became Pope Urban VIII. Galileo had six audiences (meetings) with the Pope in 1624 and received permission to publish his theory on the causes of tides, provided he did not take sides on the cosmological debate. For the next six years Galileo worked on this book, which turned into a dialogue concerning the relative merits of the Ptolemaic and the Copernican conceptions of the Universe, without reaching a conclusion of one over the other. To carry out the discussion, Galileo invented three characters: Salviati, who gave Copernicus’s views; Simplicio, who presented Aristotelian/Ptolemaic views; and Sagredo, an interested layman. Simplicio was named for an ancient Greek commentator on Aristotle. The title in English was Dialogue Concerning the Two Chief World Systems–Ptolemaic and Copernican. The publisher of the book received a license to print, and the book appeared in Florence in March 1632. An outbreak of the plague delayed copies being sent to Rome. In August of the same year an order came from the Roman Inquisition to stop all sales. Galileo’s student and friend, the Grand Duke Cosimo II, had died in 1621. The new Grand Duke of Tuscany, Ferdinand, protested the book, which seemed to him, and to many of the church leaders, to portray Simplicio as a simpleton and fool, and thus to take sides in the debate. The Pope considered the character of Simplicio an insult, as did the other church leaders. In September 1632 Galileo was charged with “vehement suspicion of heresy” and ordered to come to Rome for a trial. Ill, he did not appear until February 1633. Galileo denied that he was defending heliocentrism, but he finally admitted that one could get that impression from the book. He was threatened with torture, forced to recant the heliocentric model, and, in June of that year, sentenced to indefinite imprisonment in Rome. His book was put on the Index of Prohibited Books. Three of the ten judges disagreed with the verdict. Legend has it that as Galileo left the courtroom he whispered, “Eppur si muove [Still it (Earth) moves],” but this was most likely invented later. Galileo was crushed by the harsh verdict. The archbishop of Siena, who had disagreed with the verdict, got permission to take Galileo into his home and helped him through his depression. Two years before his trial Galileo had taken a villa on the outskirts of Florence, to be next to the convent where his daughters were nuns. After a few months in Rome, Galileo received permission to return to his own villa, to be guarded by representatives of the Inquisition, a house arrest. He was ill with a hernia, heart palpitations, and insomnia. A few months after his return home his older daughter, Maria Celeste, with whom he was very close, died in April 1634. The following year Galileo’s book, Dialogue Concerning the Two Chief World Systems–Ptolemaic and Copernican, was published in Latin in Strasburg, Alsace (France), outside the grasp of the Catholic Inquisition, thereby reaching a much more cosmopolitan audience than the suppressed Italian text. Timeline of Galileo’s life. Click here for a larger version. Download the PDF. Blindness and a Legacy of Truth Galileo rallied and in his last years wrote a book summarizing all his ideas, published in 1637 in Holland in Italian. This book was translated into English in 1661 as Discourses and Mathematical Demonstrations Relating to Two New Sciences, and Isaac Newton read it in 1666. By 1638 Galileo had become totally blind. He was allowed to live with his son in Florence and have visitors as long as they were not mathematicians. He carried on a great deal of correspondences by dictating his letters to others. He died on January 9, 1642, in Florence, at the age of 77. He was not allowed to be buried in the main body of the Basilica of Santa Croce, but in a small room at the end of a corridor; he was reburied in the main part in 1737. The Catholic Church took 200 years to remove Galileo’s book from the Index of Prohibited Books, finally doing so in 1835. In 1992 Pope John Paul II expressed regret at how the church had handled the issue of Galileo and issued a declaration acknowledging the errors committed by the court of the Catholic Church. In 2008 plans were announced for a statue of Galileo inside the Vatican walls, but in 2009 these plans were suspended. Galileo’s own words to a friend about his blindness serve as a suitable epitaph: Alas, your friend and servant Galileo has for the last month been irremediably blind, so that this heaven, this earth, this universe which I, by my remarkable discoveries and clear demonstrations had enlarged a hundred times beyond what had been believed by wise men of past ages, for me is from this time forth shrunk into so small a space as to be filled by my own sensations. (Drake, p. 107) For Further Discussion Think about the following question and write your response and any additional questions you have in the Questions Area below. How did the telescope contribute to Galileo’s discoveries? [Sources and attributions] |
Physics, Gravity & the Laws of Motion By Cynthia Stokes Brown Born: January 4, 1643; Lincolnshire, England. Died: March 31, 1727; London, England. Portrait of Isaac Newton © CORBIS Sir Isaac Newton developed the three basic laws of motion and the theory of universal gravity, which together laid the foundation for our current understanding of physics and the Universe. Early Life and Education Newton was born prematurely and not expected to survive. His dad had died before his birth, and when he was 3 his mother remarried and left him with his grandparents on a farm in Lincolnshire, England, about 100 miles north of London, while she moved to a village a mile and a half away from him. He grew up with few playmates and amused himself by contemplating the world around him. His mother returned when Newton was 11 years old and sent him to King’s School, eight miles away. Rather than playing after school with the other boys, Newton spent his free time making wooden models, kites of various designs, sundials, even a water clock. When his mother, who was hardly literate, took him out of school at 15 to turn him into a farmer, the headmaster, Henry Stokes, who recognized where Newton’s talents lay, prevailed on her to let Newton return to school and prepare for university. Newton attended Cambridge University from 1661 to 1665. The university temporarily closed soon after he got his degree because people in urban areas were dying from the plague. Newton retreated to his grandparents’ farm for two years, during which time he proved that “white” light was composed of all colors and started to figure out calculus and universal gravitation — all before he was 24 years old. It was on his grandparents’ farm that Newton sat under the famous apple tree and watched one of its fruits fall to the ground. He wondered if the force that pulled the apple to the ground could extend out to the Moon and keep it in its orbit around Earth. Perhaps that force could extend into the Universe indefinitely. Isaac Newton performing an experiment © Bettmann/CORBIS At Cambridge After the plague subsided, Newton returned to Cambridge to earn his master’s degree and become a professor of mathematics there. His lectures bored many of his students, but he continued his own thinking and experiments, undaunted. When his mother died, he inherited enough wealth to leave his teaching job and move to London, where he became the president of the Royal Society of London for Improving Natural Knowledge, the top organization of scientists in England, for 25 years. Laws of Motion and Gravity Newton’s most important book was written in Latin; its title was translated as Mathematical Principles of Natural Philosophy (1687). It proved to be one of the most influential works in the history of science. In its pages Newton asserted the three Laws of Motion, elaborated Johannes Kepler’s Laws of Motion, and stated the Law of Universal Gravitation. The book is primarily a mathematical work, in which Newton developed and applied calculus, the mathematics of change, which allowed him to understand the motion of celestial bodies. To reach his conclusions he also used accurate observations of planetary motion, which he made by designing and building a new kind of telescope, one that used mirrors to reflect, rather than lenses to refract, light. Illustration from The Mathematical Principles of Natural Philosophy by Isaac Newton © CORBIS Newton’s three Laws of Motion are: 01 - Every body continues at rest or in motion in a straight line unless compelled to change by forces impressed upon it. (Galileo first formulated this, and Newton recast it.)02 - Every change of motion is proportional to the force impressed and is made in the direction of the straight line in which that force is impressed. (A planet would continue outward into space but is perfectly balanced by the Sun’s inward pull, which Newton termed “centripetal” force.)03 - To every action there is always opposed an equal reaction, or the mutual action of two bodies on each other is always equal and directed to contrary parts. 01 - Every body continues at rest or in motion in a straight line unless compelled to change by forces impressed upon it. (Galileo first formulated this, and Newton recast it.) 02 - Every change of motion is proportional to the force impressed and is made in the direction of the straight line in which that force is impressed. (A planet would continue outward into space but is perfectly balanced by the Sun’s inward pull, which Newton termed “centripetal” force.) 03 - To every action there is always opposed an equal reaction, or the mutual action of two bodies on each other is always equal and directed to contrary parts. Putting these laws together, Newton was able to state the Law of Universal Gravitation: “Every particle of matter attracts every other particle with a force proportional to the product of the masses of the two particles and inversely proportional to the square of the distance between them.” Stated more simply, the gravitational attraction between two bodies decreases rapidly as the distance between them increases. This calculation proved powerful because it presented the Universe as an endless void filled with small material bodies moving according to harmonious, rational principles. Newton understood gravity as a universal property of all bodies, its force dependent only on the amount of matter contained in each body. Everything, from apples to planets, obeys the same unchanging laws. By combining physics, mathematics, and astronomy, Newton made a giant leap in human understanding of Earth and the cosmos. Newton’s mathematical method for dealing with changing quantities is now called the calculus. Newton did not publish his method but solved problems using it. Later the German scientist Gottfried Wilhelm von Leibniz also worked out “the calculus”, and his notation proved easier to use. Newton accused Leibniz, in a nasty dispute, of stealing his ideas, but historians now believe that each invented the calculus independently. Timeline of Newton's life. Click here for a larger version. Download PDF. Recognition Newton was made a knight by Queen Anne in 1705 and, at his death in 1727, he was buried in London’s Westminster Abbey. He now rests in a place of prominence near the poet Geoffrey Chaucer and the astronomer John Herschel. Shortly before he died, Newton remarked: I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the seashore and diverting myself in now and then finding a smoother pebble or prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me. For Further Discussion Think about the following question and write your response and any additional questions you have in the Questions Area below. How does the Law of Universal Gravitation explain the motion of the planets? [Sources and attributions] |
The Red Supergiant Betelgeuse The Red Supergiant Betelgeuse. Source: ESO/L. Calcada This is an artist's impression of the red supergiant Betelgeuse in Orion, a prominent constellation throughout the world. Betelgeuse, the 8th brightest star in the night sky, can be easily identified as one of Orion's armpits. Betelgeuse's exact size is hard to calculate but if the star were at the center of our Solar System it would entirely engulf Earth, Venus, and Mars. A Black Hole in Centaurus A A Black Hole in Centaurus A. Source: X-ray: NASA/CXC/CFA/R.Kraft et al.; Submillimeter: MPIfR/ESO/APEX/A.Weiss et al.; Optical: ESO/WFI This image of the galaxy Centaurus A demonstrates the incredible size and power of the supermassive black hole at its center. The X-ray jet in the upper left side of this image is powered by the central black hole and extends outwards for about 13,000 light years from the event horizon. The Basic Structure of a Star The Basic Structure of a Star. Source: ESA/NASA/SOHO and the Big History Project This diagram shows the basic structure of a star like our Sun. Hydrogen is fused in the star's core, forming helium and sometimes heavier elements as the fusion process continues. Incredible amounts of energy are released in the process. Source: ESA/NASA/SOHO and the Big History Project Our Sun and VY Canis Majoris Our Sun and VY Canis Majoris. This is an approximate comparison of the size difference between our Sun and the largest known star, VY Canis Majoris, in the constellation Canis Major. The diameter of VY Canis Majoris is more than 1,800 times that of the Sun. Bear in mind that these two stars are at different stages in their lives, further contributing to the size difference. The Hertzsprung-Russell Diagram The Hertzsprung-Russell Diagram. Source: ESO In the Hertzsprung-Russell Diagram, the luminosities (brightnesses) of stars are plotted against their temperatures. The position of a star in the diagram demonstrates its present stage and its mass. Stars that fuse hydrogen into helium lie on the central diagonal branch, the so-called "main sequence." Red dwarfs like AB Doradus C lie in the cool and faint corner. When a star exhausts all if its hydrogen, it leaves the main sequence and becomes a red giant or a supergiant, depending on its mass. When medium-sized stars with masses similar to our Sun age, they will swell in size and become red giants. Without enough mass to cause a supernova, they will burn all of their fuel and eventually shrink into white dwarfs (seen in the lower left). An Unstable, Dying Star Called Eta Carinae An Unstable, Dying Star Called Eta Carinae. Source: X-ray: NASA/CXC/GSFC/M. Corcoran et al: Optical: NASA/STScl Eta Carinae is a massive (100-150 solar masses) and unstable star that astronomers expect will end in a supernova. In the 1840s Eta Carinae erupted, ejecting material 10 times the mass of the Sun and briefly becoming the second brightest star in the sky - an early indication of the massive explosion expected to come. The Dying Star Eta Carinae The Dying Star Eta Carinae. Source: Jon Morse (University of Colorado) and NASA In this image of Eta Carinae, the dying star resembles a cancerous tumor or an infected organ. Eta Carinae's final demise is likely to be a supernova that will look as bright as the full Moon. Tycho's Supernova Remnant Tycho's Supernova Remnant. Source: X-ray: NASA/CXC/SAO; Infrared: NASA/JPL-Caltech; Optical: MPIA, Calar Alto, O. Krause et al. This blazing hot cloud of gas and debris in the constellation Cassiopeia, SN 1572 or B Cas, is the remnant of the supernova that Tycho Brahe and other astronomers and stargazers witnessed in November 1572. This bright explosion deep in space demonstrated to astronomers like Brahe that the Universe was alive and in constant motion. |
Pure Metal: Jābir Ibn Ḥayyān By Trevor R. Getz Whether an individual or a collection of people, Jābir ibn Ḥayyān’s work with chemical substances was an inspiration and guide for the later creators of chemistry. The original transformer Whether you realize it or not, you wake up every morning and do some chemistry. You might turn the liquids in your eggs into solids. Maybe you remove the moisture inside your bread to make toast. Meanwhile, your parents may be adding hot water to ground-up beans to create new and complex compounds that taste good and give them a caffeine buzz. Chemistry is everywhere. Chemistry is the modern science that deals with the structure and properties of substances and how they are transformed. But modern chemistry didn’t just happen. It grew out of a long history of curious humans who used trial and error to answer questions like: How do you make raw foods edible?How do you turn ash and fat into soap?How do you turn mineral-bearing rocks into iron? Most trials ended in error, but when they succeeded, people passed on the ideas to later generations, which helped expand our collective learning. But these ideas weren’t always studied in a scientific way. Between the days of trial and error and the arrival of modern science was something called alchemy. Not exactly science, and not exactly magic, alchemy mixes religion, spirituality, and experimentation in order to study the properties of natural substances, especially metals. Perhaps the greatest of the alchemists was Jābir ibn Ḥayyān, a Muslim Persian innovator who wrote over 3,000 texts on alchemy. These included: A list—including descriptions—of all the known tools and equipment used by Greek and Muslim alchemistsHistories of the progress made by earlier alchemistsPerhaps most important, studies of the characteristics of different metals You see, ibn Ḥayyān was one of the first people to describe the qualities of different metals, and he had a good reason for doing so. Alchemists wanted to know how you might transform one metal into another. Well, what they really wanted to do was to turn lead, a cheap metal, into gold, an expensive metal. The way to pursue that challenge was to study the qualities of each metal. Then they had to figure out the process by which you might change those qualities. In what may be his most important contribution to later scientists, ibn Ḥayyān began to study how mixing substances—using heat, acid, and other methods and tools—could change them. These processes included: Distillation – Purifying something by boiling it and then capturing the steam.Filtration – Putting a substance through a filter to remove impurities.Amalgamation – Mixing two substances together so they become a new substance. Jābir ibn Ḥayyān’s experiments resulted in achievements that included the isolation of sulfuric acid and nitric acid and the purification of gold and mercury. These experiments were recorded and shared with others, and helped inform future generations of scholars. By BHP and Peter Quatch, CC BY-NC 4.0. In the process of his work with metals, ibn Ḥayyān learned how to purify gold and mercury. He also isolated substances that could be used to transform other metals, including sulfuric acid and nitric acid. A man? Or a school? Who was this brilliant man who wrote 3,000 texts and invented new ways to transform substances? It’s still a mystery. There probably was a man named Jābir ibn Ḥayyān. He was probably born in the city of Tus, in Persia. He probably worked for the Abbasid ruler Harun al-Rashid. And he probably wrote some of the 3,000 texts associated with his name. But it’s likely that a lot of the work that people attach his name to was written by other people living around the same time or later. So, if that’s true, we’re looking at something much more exciting than a single innovator. We’re probably looking at a whole school of alchemists. Many of them were probably students of ibn Ḥayyān’s, working together, sharing notes and ideas, and passing them on. If the 3,000 texts were written by several or many people, then we have evidence of a great effort to understand metals and other substances and transform them. Maybe they all worked together in a laboratory, or workshop. Maybe there was even a whole school of alchemists in one location! From Jābir to Geber to.... And, if it were a school, what an important school it was! The work of Jābir ibn Ḥayyān spread across the Islamic world and was preserved for later researchers—and there’s no “maybe” about that. This work was highly influential. The ibn Ḥayyān texts were translated into Latin, and by the twelfth century, they were found in Spain, Italy, and England. One group of fourteenth-century Spanish experimenters even signed their own work “Geber” to honor the influence of “Jābir.” Later, Sir Isaac Newton studied ibn Ḥayyān, and in his own studies on the nature of matter, he reproduced some of these earlier experiments. Ibn Ḥayyān’s work looked quite different from the work of modern scientists. Yet, like many great innovators before the modern period, ibn Ḥayyān helped pave the way for later scholars who used the scientific method. His work featured many methods that later scientists would adopt. These include some of the first attempts to create a list of qualities that compare one metal to another. He also invented both new tools and new liquids in his ambition to transform one substance into another. Finally, he recorded everything very carefully. Whether he was one man, or a whole school or laboratory of scientists, ibn Ḥayyān represents an important step between the trial and error of everyday work and the carefully recorded and studied science of chemistry. Author bio Trevor Getz is a professor of African History at San Francisco State University. He has written 11 books on African and world history, including Abina and the Important Men. He is also the author of A Primer for Teaching African History, which explores questions about how we should teach the history of Africa in high school and university classes. [Sources and attributions] |
The Graphic Biography below uses “Three Close Reads”. If you want to learn more about this strategy, click here. Reading 1: Skimming for gist This will be your quickest read. It should help you get the general idea of what the graphic biography will be about. Pay attention to the title, headings, images, and layout. Ask yourself: what is this graphic biography going to be about? Reading 2: Understanding content For this reading, you should be looking for unfamiliar vocabulary words, the major claim and key supporting details, and analysis and evidence. You should also spend some time looking at the images and the way in which the page is designed. By the end of the second close read, you should be able to answer the following questions: What issues did Chandra face when he presented his calculations about the death of stars?What was Chandra's experience at the University of Chicago like?What was Chandra's most important contribution to collective learning?How has the artist designed the images in this comic to help you know in which order to read the text?Looking at just the images, what do you think is the theme of this comic? What issues did Chandra face when he presented his calculations about the death of stars? What was Chandra's experience at the University of Chicago like? What was Chandra's most important contribution to collective learning? How has the artist designed the images in this comic to help you know in which order to read the text? Looking at just the images, what do you think is the theme of this comic? Reading 3: Evaluating and Corroborating In this read, you should use the graphic biography as evidence to support, extend, or challenge claims made in the course. At the end of the third read, you should be able to respond to these questions: What does Chandra's experience sharing his ideas about stars teach you about the process of collective learning? His did his theory become accepted? Now that you know what to look for, it’s time to read! Remember to return to these questions once you’ve finished reading. The Evolving Star: Subrahmanyan Chandrasekhar - Graphic Biography Writer: Eman M. Elshaikh Artist: Kay Sohini Subrahmanyan Chandrasekhar was an Indian physicist who won the Nobel Prize for Physics. His work gave us tremendous insights into the life and death of stars. Download the Graphic Biography PDF here or click on the image above. |
All of the following terms appear in this unit. The terms are arranged here in alphabetical order. carbon — A chemical element with six protons that is the basis for all known life on Earth. chemical element — A substance whose atoms are all the same (that is, each atom contains the same number of protons as each of the other atoms in the substance). Sometimes, the word “element” is used to refer to the atoms or atomic nuclei themselves, as in the statement “Many elements are formed as products of dying stars.” chemistry — The scientific study of the composition, structure, properties, and reactions of different forms of matter. cluster — A group of galaxies held together by their mutual gravitational pulls. cosmic horizon — The distance in our Universe beyond which we cannot see (46-billion to 47-billion light- years from Earth). Light from beyond the cosmic horizon has not yet had enough time (in the history of the Universe) to reach us. density — The mass per unit of volume of a substance. fusion (also called nuclear fusion) — The combining of lighter atomic nuclei into heavier atomic nuclei. This process can release a great deal of energy, and is what powers most stars. galaxy — A huge system of stars, interstellar dust, and dark matter, held together by mutual gravitational pull. ion — An atom that has a different number of protons than electrons, giving it an overall positive or negative charge. iron — A chemical element with 26 protons. The most common chemical element in the planet Earth, iron forms the majority of Earth’s inner and outer core. The process of creating new elements through nuclear fusion in stars ends with iron, since fusing atomic nuclei together to produce elements heavier than iron does not produce energy. Milky Way galaxy — The spiral-shaped galaxy that contains our Solar System. neutron star — One possible end product of supernovae. When a star much more massive than our Sun runs out of fuel, its core may collapse to produce a ball of neutrons more dense than virtually anything else in the Universe. periodicity — Regular, recurring trends. For example, a Cepheid variable star exhibits periodicity because its brightness changes in a regular, predictable way that repeats over time. periodic table of elements — The generally accepted system for organizing the known chemical elements. Russian chemist Dmitri Mendeleev first used this method of arrangement in 1869. As new elements are discovered, they are added to the table. plasma — A state of matter in which protons and electrons are not bound together. This was the state of the entire Universe roughly before 380,000 years after the Big Bang, and is the normal state inside stars. radioactivity — The breakdown of an unstable atomic nucleus, such as uranium, through the spontaneous emission of subatomic particles. star — A huge, glowing ball of plasma held together by its own gravity. Stars, the first complex entities in the Universe, have structure, stability, and a sustained flow of energy due to nuclear fusion at their centers. supercluster — A large group of galaxy clusters that together form some of the largest known structures in the Universe. supernova — The explosion of a large star at the end of its life; most chemical elements are created by supernova explosions. |
A Closer Look at the Popular Metal A Greek silver tetradrachm from about 160 BCE © Hoberman Collection/CORBIS By Big History Project It’s amazing how much you can learn when you look at things through the lens of Big History. Take a medium-weight element like silver, a shiny whitish metal with an unassuming spot (atomic number 47) on the periodic table between palladium and cadmium. The value of silver Silver puts the luster in jewelry, helps our cell phones and MP3 players work better, and even makes hospitals safer. Let’s explore the many roles that silver has played throughout history. What makes silver more valuable to us than other minerals? Its beauty is one thing. This attractive and reflective metal has fascinated men and women for a long time. Silver also is fairly scarce — and things that are both beautiful and rare tend to be worth a lot (think diamonds, gold, and masterpieces of art). Silver is very durable, too. And it’s malleable, meaning it’s easy to shape. All these qualities have made silver very useful and valuable to this day. Silver’s monetary value has long been appreciated. Thought to be perhaps the oldest coin, the “Lydian Lion” was minted in modern-day Turkey some 2,700 years ago; early metalworkers — chemists of sorts — made the coins from electrum, an alloy of gold and silver. The Minoan civilization, which flourished on the island of Crete around 2000 BCE, and the Mycenaean people of early mainland Greece imported great amounts of silver mined in ancient Armenia. Transport of the metal between all of these places helped to accelerate trade throughout the Mediterranean region. After the catastrophic destruction of the Minoan civilization in 1600 BCE, and the decline of the Mycenaean culture around 1200 BCE, silver’s prominence continued as production shifted with the rising civilization of Classical Greece. The silver mines of Laurium (near Athens) paid for the Italian lumber used to build the fleets of triremes (warships with three levels of rowers) that made ancient Athens a naval superpower. The Romans would later adopt silver as one of their main currencies as well. Silver helped advance global civilization by connecting East and West through trade. Silver was scarce in China, but nonetheless much valued as currency. So, during the Middle Ages, Europeans used silver to buy Chinese goods — gunpowder, tea, ceramics, and silk — which were then carried over the fabled “Silk Road.” Later, when the Spanish discovered silver mines in Mexico and Peru, they established a sailing route across the Pacific, trading South American silver, some of it plundered, for Chinese silk. Silk was desirable because it made light and cool clothing much in demand by Spanish settlers in the hot, humid climate in parts of Mexico, Central America, and South America. As we’ll see elsewhere in this course, when goods get traded, so do ideas. So silver played a role in advancing collective learning. A 1739 Spanish silver dollar, also called a “piece of eight,” public domain By the 17th century, Mexican “pieces of eight” — also known as “Spanish dollars” — had become the world’s first global currency. The U.S. dollar was based on these coins and for a long time many U.S. coins contained silver. The Latin word for silver is argentum. What South American country sounds like that? Right — Argentina! During the time of the Spanish explorers in the 1500s, Argentina was thought to be rich in what shiny metal element? Silver, of course. The many uses of silver Silver also has strong antibacterial properties that have been acknowledged for millennia. The ancient Greek physician Hippocrates, sometimes called the “father of medicine,” wrote of silver’s healing properties, and early records indicate that the Phoenicians used silver vessels to keep water, wine, and vinegar pure during their long voyages at sea. You may have heard the phrase “born with a silver spoon in your mouth.” That’s not necessarily about being rich. In the 18th century, babies fed with silver spoons were thought to be healthier than those fed with spoons made from wood or other materials. Today many hospitals fight infections with equipment that is embedded with silver. Silver is even used in the thread of some socks. Why? The silver kills bacteria that make the socks smell bad! Silver is the best metallic conductor of electricity, better than copper or gold. That’s why so many electronics, like your computer keyboard or music player, rely on it. Alloys of silver are used in dentistry, photography, even in the operation of nuclear power plants. Silver also helps keep airplanes aloft. Because of its poor coefficient of friction (meaning, it’s slippery!), silver is used to coat the ball bearings used in jet engines. But did you know that billions of years ago there was no silver anywhere in the Universe? So where did it come from? Like most other elements in the periodic table, silver was created in dying stars — and in the cataclysmic supernova explosions that sometimes marked their final demise. This is the only place where temperatures get hot enough to fuse hydrogen nuclei together to form larger atoms. These larger, heavier atoms eventually went on to help form planets like Earth. So in a sense, silver, like everything else around you, was made from the first atoms of hydrogen. Where and when was hydrogen created? In the Big Bang itself. It turns out silver has a pretty big history! For Further Discussion Think about how the properties and location of chemical elements such as silver impact our lives today. What would be different if silver were as plentiful as carbon?What would it mean if silver were only found in one place on the planet? What would be different if silver were as plentiful as carbon? What would it mean if silver were only found in one place on the planet? Share your answer to one of these questions in the Questions Area below. [Sources and attributions] |
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