# Life in the Universe

## Searching for Life beyond Earth

### Learning Objectives

By the end of this section, you will be able to:
1. Outline what we have learned from exploration of the environment on Mars
2. Identify where in the solar system life is most likely sustainable and why
3. Describe some key missions and their findings in our search for life beyond our solar system
4. Explain the use of biomarkers in the search for evidence of life beyond our solar system
Astronomers and planetary scientists continue to search for life in the solar system and the universe at large. In this section, we discuss two kinds of searches. First is the direct exploration of planets within our own solar system, especially Mars and some of the icy moons of the outer solar system. Second is the even more difficult task of searching for evidence of life—a biomarker—on planets circling other stars. In the next section, we will examine SETI, the search for extraterrestrial intelligence. As you will see, the approaches taken in these three cases are very different, even though the goal of each is the same: to determine if life on Earth is unique in the universe.

### Life on Mars

The possibility that Mars hosts, or has hosted, life has a rich history dating back to the “canals” that some people claimed to see on the martian surface toward the end of the nineteenth century and the beginning of the twentieth. With the dawn of the space age came the possibility to address this question up close through a progression of missions to Mars that began with the first successful flyby of a robotic spacecraft in 1964 and have led to the deployment of capable rovers, like Curiosity and Perseverance, with instruments to look for organic chemistry.
The earliest missions to Mars provided some hints that liquid water—one of life’s primary requirements—may once have flowed on the surface, and later missions have strengthened this conclusion. The NASA Viking landers, whose purpose was to search directly for evidence of life on Mars, arrived on Mars in 1976. Viking’s onboard instruments found no organic molecules (the stuff of which life is made), and no evidence of biological activity in the martian soils it analyzed.
This result is not particularly surprising because, despite the evidence of flowing liquid water in the past, liquid water on the surface of Mars is generally not stable today. Over much of Mars, temperatures and pressures at the surface are so low that pure water would either freeze or boil away (under very low pressures, water will boil at a much lower temperature than usual). To make matters worse, unlike Earth, Mars does not have a magnetic field and ozone layer to protect the surface from harmful solar ultraviolet radiation and energetic particles. However, Viking’s analyses of the soil said nothing about whether life may have existed in Mars’ distant past, when liquid water was more abundant. We do know that water in the form of ice exists in abundance on Mars, not so deep beneath its surface. Water vapor is also a constituent of the atmosphere of Mars.
Since the visit of Viking, our understanding of Mars has deepened spectacularly. Orbiting spacecraft have provided ever-more detailed images of the surface and detected the presence of minerals that could have formed only in the presence of liquid water. Two bold surface missions, the Mars Exploration Rovers Spirit and Opportunity (2004), followed by the much larger Curiosity Rover (2012), confirmed these remote-sensing data. All three rovers found abundant evidence for a past history of liquid water, revealed not only from the mineralogy of rocks they analyzed, but also from the unique layering of rock formations.
Curiosity has gone a step beyond evidence for water and confirmed the existence of habitable environments on ancient Mars. “Habitable” means not only that liquid water was present, but that life’s requirements for energy and elemental raw materials could also have been met. The strongest evidence of an ancient habitable environment came from analyzing a very fine-grained rock called a mudstone—a rock type that is widespread on Earth but was unknown on Mars until Curiosity found it (see ). The mudstone can tell us a great deal about the wet environments in which they formed.  The Perseverance rover is collecting samples of sedimentary rock in a former lakebed, to later return to Earth for laboratory analysis.
Five decades of robotic exploration have allowed us to develop a picture of how Mars evolved through time. Early Mars had epochs of warmer and wetter conditions that would have been conducive to life at the surface. However, Mars eventually lost much of its early atmosphere and the surface water began to dry up. As that happened, the ever-shrinking reservoirs of liquid water on the martian surface became saltier and more acidic, until the surface finally had no significant liquid water and was bathed in harsh solar radiation. The surface thus became uninhabitable, but this might not be the case for the planet overall.
Reservoirs of ice and liquid water could still exist underground, where pressure and temperature conditions make it stable. There is recent evidence to suggest that liquid water (probably very salty water) can occasionally (and briefly) flow on the surface even today. Thus, Mars might even have habitable conditions in the present day, but of a much different sort than we normally think of on Earth.
Our study of Mars reveals a planet with a fascinating history—one that saw its ability to host surface life dwindle billions of years ago, but perhaps allowing life to adapt and survive in favorable environmental niches. Even if life did not survive, we expect that we might find evidence of life if it ever took hold on Mars. If it is there, it is hidden in the crust, and we are still learning how best to decipher that evidence.

### Life in the Outer Solar System

The massive gas and ice giant planets of the outer solar system—Jupiter, Saturn, Uranus, and Neptune—are almost certainly not habitable for life as we know it, but some of their moons might be (see ). Although these worlds in the outer solar system contain abundant water, they receive so little warming sunlight in their distant orbits that it was long believed they would be “geologically dead” balls of hard-frozen ice and rock. But, as we saw in the chapter on Rings, Moons, and Pluto, missions to the outer solar system have found something much more interesting.
Jupiter’s moon Europa revealed itself to the Voyager and Galileo missions as an active world whose icy surface apparently conceals an ocean with a depth of tens to perhaps a hundred kilometers. As the moon orbits Jupiter, the planet’s massive gravity creates tides on Europa—just as our own Moon’s gravity creates our ocean tides—and the friction of all that pushing and pulling generates enough heat to keep the water in liquid form (). Similar tides act upon other moons if they orbit close to the planet. Scientists now think that six or more of the outer solar system’s icy moons may harbor liquid water oceans for the same reason. Among these, Europa and Enceladus, a moon of Saturn, have thus far been of greatest interest to astrobiologists.
Europa has probably had an ocean for most or all of its history, but habitability requires more than just liquid water. Life also requires energy, and because sunlight does not penetrate below the kilometers-thick ice crust of Europa, this would have to be chemical energy. One of Europa’s key attributes from an astrobiology perspective is that its ocean is most likely in direct contact with an underlying rocky mantle, and the interaction of water and rocks—especially at high temperatures, as within Earth’s hydrothermal vent systems—yields a reducing chemistry (where molecules tend to give up electrons readily) that is like one half of a chemical battery. To complete the battery and provide energy that could be used by life requires that an oxidizing chemistry (where molecules tend to accept electrons readily) also be available. On Earth, when chemically reducing vent fluids meet oxygen-containing seawater, the energy that becomes available often supports thriving communities of microorganisms and animals on the sea floor, far from the light of the Sun.
The Galileo mission found that Europa’s icy surface does contain an abundance of oxidizing chemicals. This means that availability of energy to support life depends very much on whether the chemistry of the surface and the ocean can mix, despite the kilometers of ice in between. That Europa’s ice crust appears geologically “young” (only tens of millions of years old, on average) and that it is active makes it tantalizing to think that such mixing might indeed occur. Understanding whether and how much exchange occurs between the surface and ocean of Europa will be a key science objective of future missions to Europa, and a major step forward in understanding whether this moon could be a cradle of life.
In 2005, the Cassini mission performed a close flyby of a small (500-kilometer diameter) moon of Saturn, Enceladus (), and made a remarkable discovery. Plumes of gas and icy material were venting from the moon’s south polar region at a collective rate of about 250 kilograms of material per second. Several observations, including the discovery of salts associated with the icy material, suggest that their source is a liquid water ocean beneath tens of kilometers of ice. Although it remains to be shown definitively whether the ocean is local or global, transient or long-lived, it does appear to be in contact, and to have reacted, with a rocky interior. As on Europa, this is probably a necessary—though not sufficient—condition for habitability. What makes Enceladus so enticing to planetary scientists, though, are those plumes of material that seem to come directly from its ocean: samples of the interior are there for the taking by any spacecraft sent flying through. For a future mission, such samples could yield evidence not only of whether Enceladus is habitable but, indeed, of whether it is home to life.
Saturn’s big moon Titan is very different from both Enceladus and Europa (see ). Although it may host a liquid water layer deep within its interior, it is the surface of Titan and its unusual chemistry that makes this moon such an interesting place. Titan’s thick atmosphere—the only one among moons in the solar system—is composed mostly of nitrogen but also of about 5% methane. In the upper atmosphere, the Sun’s ultraviolet light breaks apart and recombines these molecules into more complex organic compounds that are collectively known as tholins. The tholins shroud Titan in an orange haze, and imagery from Cassini and from the Huygens probe that descended to Titan’s surface show that heavier particles appear to accumulate on the surface, even forming “dunes” that are cut and sculpted by flows of liquid hydrocarbons (such as liquid methane). Some scientists see this organic chemical factory as a natural laboratory that may yield some clues about the solar system’s early chemistry—perhaps even chemistry that could support the origin of life.

### Habitable Planets Orbiting Other Stars

One of the most exciting developments in astronomy during the last two decades is the ability to detect exoplanets—planets orbiting other stars. As we saw in the chapter on the formation of stars and planets, since the discovery of the first exoplanet in 1995, there have been thousands of confirmed detections, and many more candidates that are not yet confirmed. These include several dozen possibly habitable exoplanets. Such numbers finally allow us to make some predictions about exoplanets and their life-hosting potential. The majority of stars with mass similar to the Sun appear to host at least one planet, with multi-planet systems like our own not unusual. How many of these planets might be habitable, and how could we search for life there?
In evaluating the prospect for life in distant planetary systems, astrobiologists have developed the idea of a habitable zone—a region around a star where suitable conditions might exist for life. This concept focuses on life’s requirement for liquid water, and the habitable zone is generally thought of as the range of distances from the central star in which water could be present in liquid form at a planet’s surface. In our own solar system, for example, Venus has surface temperatures far above the boiling point of water and Mars has surface temperatures that are almost always below the freezing point of water. Earth, which orbits between the two, has a surface temperature that is “just right” to keep much of our surface water in liquid form.
Whether surface temperatures are suitable for maintaining liquid water depends on a planet’s “radiation budget” —how much starlight energy it absorbs and retains—and whether or how processes like winds and ocean circulation distribute that energy around the planet. How much stellar energy a planet receives, in turn, depends on how much and what sort of light the star emits and how far the planet is from that star,The amount of starlight received per unit area of a planet’s surface (per square meter, for example) decreases with the square of the distance from the star. Thus, when the orbital distance doubles, the illumination decreases by 4 times (2 how much it reflects back to space, and how effectively the planet’s atmosphere can retain heat through the greenhouse effect (see Earth as a Planet). All of these can vary substantially, and all matter a lot. For example, Venus receives about twice as much starlight per square meter as Earth but, because of its dense cloud cover, also reflects about twice as much of that light back to space as Earth does. Mars receives only about half as much starlight as Earth, but also reflects only about half as much. Thus, despite their differing orbital distances, the three planets actually absorb comparable amounts of sunlight energy. Why, then, are they so dramatically different?
As we learned in several chapters about the planets, some of the gases that make up planetary atmospheres are very effective at trapping infrared light—the very range of wavelengths at which planets radiate thermal energy back out to space—and this can raise the planet’s surface temperature quite a bit more than would otherwise be the case. This is the same “greenhouse effect” that is of such concern for global warming on our planet. Earth’s natural greenhouse effect, which comes mostly from water vapor and carbon dioxide in the atmosphere, raises our average surface temperature by about 33 °C over the value it would have if there were no greenhouse gases in the atmosphere. Mars has a very thin atmosphere and thus very little greenhouse warming (about 2 °C worth), while Venus has a massive carbon dioxide atmosphere that creates very strong greenhouse warming (about 510 °C worth). These worlds are much colder and much hotter, respectively, than Earth would be if moved into their orbits. Thus, we must consider the nature of any atmosphere as well as the distance from the star in evaluating the range of habitability.
Of course, as we have learned, stars also vary widely in the intensity and spectrum (the wavelengths of light) they emit. Some are much brighter and hotter (bluer), while others are significantly dimmer and cooler (redder), and the distance of the habitable zone varies accordingly. For example, the habitable zone around M-dwarf stars is 3 to 30 times closer in than for G-type (Sun-like) stars. There is a lot of interest in whether such systems could be habitable because—although they have some potential downsides for supporting life—M-dwarf stars are by far the most numerous and long-lived in our Galaxy.
The luminosity of stars like the Sun also increases over their main-sequence lifetime, and this means that the habitable zone migrates outward as a star system ages. Calculations indicate that the power output of the Sun, for example, has increased by at least 30% over the past 4 billion years. Thus, Venus was once within the habitable zone, while Earth received a level of solar energy insufficient to keep the modern Earth (with its present atmosphere) from freezing over. In spite of this, there is plenty of geological evidence that liquid water was present on Earth’s surface billions of years ago. The phenomenon of increasing stellar output and an outwardly migrating habitable zone has led to another concept: the continuously habitable zone is defined by the range of orbits that would remain within the habitable zone during the entire lifetime of the star system. As you might imagine, the continuously habitable zone is quite a bit narrower than the habitable zone is at any one time in a star’s history. The nearest star to the Sun, Proxima Centauri, is an M star that has a planet with a mass of at least 1.3 Earth masses, taking about 11 days to orbit. At the distance for such a quick orbit (0.05 AU), the planet may be in the habitable zone of its star, although whether conditions on such a planet near such a star are hospitable for life is a matter of great scientific debate.
Even when planets orbit within the habitable zone of their star, it is no guarantee that they are habitable. For example, Venus today has virtually no water, so even if it were suddenly moved to a “just right” orbit within the habitable zone, a critical requirement for life would still be lacking.
Scientists are working to understand all the factors that define the habitable zone and the habitability of planets orbiting within that zone because this will be our primary guide in targeting exoplanets on which to seek evidence of life. As technology for detecting exoplanets has advanced, so too has our potential to find Earth-size worlds within the habitable zones of their parent stars. Of the confirmed or candidate exoplanets known at the time of writing, nearly 300 are considered to be orbiting within the habitable zone and more than 10% of those are roughly Earth-size.

### Biomarkers

Our observations suggest increasingly that Earth-size planets orbiting within the habitable zone may be common in the Galaxy—current estimates suggest that more than 40% of stars have at least one. But are any of them inhabited? With no ability to send probes there to sample, we will have to derive the answer from the light and other radiation that come to us from these faraway systems (). What types of observations might constitute good evidence for life?
To be sure, we need to look for robust biospheres (atmospheres, surfaces, and/or oceans) capable of creating planet-scale change. Earth hosts such a biosphere: the composition of our atmosphere and the spectrum of light reflected from our planet differ considerably from what would be expected in the absence of life. Presently, Earth is the only body in our solar system for which this is true, despite the possibility that habitable conditions might prevail in the subsurface of Mars or inside the icy moons of the outer solar system. Even if life exists on these worlds, it is very unlikely that it could yield planet-scale changes that are both telescopically observable and clearly biological in origin.
What makes Earth “special” among the potentially habitable worlds in our solar system is that it has a photosynthetic biosphere. This requires the presence of liquid water at the planet’s surface, where organisms have direct access to sunlight. The habitable zone concept focuses on this requirement for surface liquid water—even though we know that subsurface habitable conditions could prevail at more distant orbits—exactly because these worlds would have biospheres detectable at a distance.
Indeed, plants and photosynthetic microorganisms are so abundant at Earth’s surface that they affect the color of the light that our planet reflects out into space—we appear greener in visible wavelengths and reflect more near-infrared light than we otherwise would. Moreover, photosynthesis has changed Earth’s atmosphere at a large scale—more than 20% of our atmosphere comes from the photosynthetic waste product, oxygen. Such high levels would be very difficult to explain in the absence of life. Other gases, such as nitrous oxide and methane, when found simultaneously with oxygen, have also been suggested as possible indicators of life. When sufficiently abundant in an atmosphere, such gases could be detected by their effect on the spectrum of light that a planet emits or reflects. (As we saw in the chapter on exoplanets, astronomers today are beginning to have the capability of detecting the spectrum of the atmospheres of some planets orbiting other stars.)
Astronomers have thus concluded that, at least initially, a search for life outside our solar system should focus on exoplanets that are as much like Earth as possible—roughly Earth-size planets orbiting in the habitable zone—and look for the presence of gases in the atmosphere or colors in the visible spectrum that are hard to explain except by the presence of biology. Simple, right? In reality, the search for exoplanet life poses many challenges.
As you might imagine, this task is more challenging for planetary systems that are farther away and, in practical terms, this will limit our search to the habitable worlds closest to our own. Should we become limited to a very small number of nearby targets, it will also become important to consider the habitability of planets orbiting the M-dwarfs we discussed above.
If we manage to separate out a clean signal from the planet and find some features in the light spectrum that might be indicative of life, we will need to work hard to think of any nonbiological process that might account for them. “Life is the hypothesis of last resort,” noted astronomer Carl Sagan—meaning that we must exhaust all other explanations for what we see before claiming to have found evidence of extraterrestrial biology. This requires some understanding of what processes might operate on worlds that we will know relatively little about; what we find on Earth can serve as a guide but also has potential to lead us astray ().
Recall, for example, that it would be extremely difficult to account for the abundance of oxygen in Earth’s atmosphere except by the presence of biology. But it has been hypothesized that oxygen could build up to substantial levels on planets orbiting M-dwarf stars through the action of ultraviolet radiation on the atmosphere—with no need for biology. It will be critical to understand where such “false positives” might exist in carrying out our search.
We need to understand that we might not be able to detect biospheres even if they exist. Life has flourished on Earth for perhaps 3.5 billion years, but the atmospheric “biosignatures” that, today, would supply good evidence for life to distant astronomers have not been present for all of that time. Oxygen, for example, accumulated to detectable levels in our atmosphere only a little over 2 billion years ago. Could life on Earth have been detected before that time? Scientists are working actively to understand what additional features might have provided evidence of life on Earth during that early history, and thereby help our chances of finding life beyond.

### Key Concepts and Summary

The search for life beyond Earth offers several intriguing targets. Mars appears to have been more similar to Earth during its early history than it is now, with evidence for liquid water on its ancient surface and perhaps even now below ground. The accessibility of the martian surface to our spacecraft offers the exciting potential to directly examine ancient and modern samples for evidence of life. In the outer solar system, the moons Europa and Enceladus likely host vast sub-ice oceans that may directly contact the underlying rocks—a good start in providing habitable conditions—while Titan offers a fascinating laboratory for understanding the sorts of organic chemistry that might ultimately provide materials for life. And the last decade of research on exoplanets leads us to believe that there may be billions of habitable planets in the Milky Way Galaxy. Study of these worlds offers the potential to find biomarkers indicating the presence of life.


# Life in the Universe

## The Search for Extraterrestrial Intelligence

### Learning Objectives

By the end of this section, you will be able to:
1. Explain why spaceships from extraterrestrial civilizations are unlikely to have visited us
2. List efforts by humankind to communicate with other civilizations via messages on spacecraft
3. Understand the various SETI programs scientists are undertaking
Given all the developments discussed in this chapter, it seems likely that life could have developed on many planets around other stars. Even if that life is microbial, we saw that we may soon have ways to search for chemical biosignatures. This search is of fundamental importance for understanding biology, but it does not answer the question, “Are we alone?” that we raised at the beginning of this chapter. When we ask this question, many people think of other intelligent creatures, perhaps beings that have developed technology similar to our own. If any intelligent, technical civilizations have arisen, as has happened on Earth in the most recent blink of cosmic time, how could we make contact with them?
This problem is similar to making contact with people who live in a remote part of Earth. If students in the United States want to converse with students in Australia, for example, they have two choices. Either one group gets on an airplane and travels to meet the other, or they communicate by sending a message remotely. Given how expensive airline tickets are, most students would probably select the message route.
In the same way, if we want to get in touch with intelligent life around other stars, we can travel, or we can try to exchange messages. Because of the great distances involved, interstellar space travel would be very slow and prohibitively expensive. The fastest spacecraft the human species has built so far would take almost 80,000 years to get to the nearest star. While we could certainly design a faster craft, the more quickly we require it to travel, the greater the energy cost involved. To reach neighboring stars in less than a human life span, we would have to travel close to the speed of light. In that case, however, the expense would become truly astronomical.

### Interstellar Travel

Bernard Oliver, an engineer with an abiding interest in life elsewhere, made a revealing calculation about the costs of rapid interstellar space travel. Since we do not know what sort of technology we (or other civilizations) might someday develop, Oliver considered a trip to the nearest star (and back again) in a spaceship with a “perfect engine”—one that would convert its fuel into energy with 100% efficiency. Even with a perfect engine, the energy cost of a single round-trip journey at 70% the speed of light turns out to be equivalent to several hundred thousand years’ worth of total U.S. electrical energy consumption. The cost of such travel is literally out of this world.
This is one reason astronomers are so skeptical about claims that UFOs are spaceships from extraterrestrial civilizations. Given the distance and energy expense involved, it seems unlikely that the dozens of UFOs (and even UFO abductions) claimed each year could be visitors from other stars so fascinated by Earth civilization that they are willing to expend fantastically large amounts of energy or time to reach us. Nor does it seem credible that these visitors have made this long and expensive journey and then systematically avoided contacting our governments or political and intellectual leaders.
Not every UFO report has been explained (in many cases, the observations are sketchy or contradictory). But investigation almost always converts them to IFOs (identified flying objects) or NFOs (not-at-all flying objects). While some are hoaxes, others are natural phenomena, such as bright planets, ball lightning, fireballs (bright meteors), or even flocks of birds that landed in an oil slick to make their bellies reflective. Still others are human craft, such as private planes with some lights missing, or secret military aircraft. It is also interesting that the group of people who most avidly look at the night sky, the amateur astronomers, have never reported UFO sightings. Further, not a single UFO has ever left behind any physical evidence that can be tested in a laboratory and shown to be of nonterrestrial origin.
Another common aspect of belief that aliens are visiting Earth comes from people who have difficulty accepting human accomplishments. There are many books and TV shows, for example, that assert that humans could not have built the great pyramids of Egypt, and therefore they must have been built by aliens. The huge statues (called Moai) on Easter Island are also sometimes claimed to have been built by aliens. Some people even think that the accomplishments of space exploration today are based on alien technology.
However, the evidence from archaeology and history is clear: ancient monuments were built by ancient people, whose brains and ingenuity were every bit as capable as ours are today, even if they didn’t have electronic textbooks like you do.

### Messages on Spacecraft

While space travel by living creatures seems very difficult, robot probes can travel over long distances and over long periods of time. Five spacecraft—two Pioneers, two Voyagers, and New Horizons—are now leaving the solar system. At their coasting speeds, they will take hundreds of thousands or millions of years to get anywhere close to another star. On the other hand, they were the first products of human technology to go beyond our home system, so we wanted to put messages on board to show where they came from.
Each Pioneer carries a plaque with a pictorial message engraved on a gold-anodized aluminum plate (). The Voyagers, launched in 1977, have audio and video records attached, which allowed the inclusion of over 100 photographs and a selection of music from around the world. Given the enormous space between stars in our section of the Galaxy, it is very unlikely that these messages will ever be received by anyone. They are more like a note in a bottle thrown into the sea by a shipwrecked sailor, with no realistic expectation of its being found soon but a slim hope that perhaps someday, somehow, someone will know of the sender’s fate.

### Communicating with the Stars

If direct visits among stars are unlikely, we must turn to the alternative for making contact: exchanging messages. Here the news is a lot better. We already use a messenger—light or, more generally, electromagnetic waves—that moves through space at the fastest speed in the universe. Traveling at 300,000 kilometers per second, light reaches the nearest star in only 4 years and does so at a tiny fraction of the cost of sending material objects. These advantages are so clear and obvious that we assume they will occur to any other species of intelligent beings that develop technology.
However, we have access to a wide spectrum of electromagnetic radiation, ranging from the longest-wavelength radio waves to the shortest-wavelength gamma rays. Which would be the best for interstellar communication? It would not be smart to select a wavelength that is easily absorbed by interstellar gas and dust, or one that is unlikely to penetrate the atmosphere of a planet like ours. Nor would we want to pick a wavelength that has lots of competition for attention in our neighborhood.
One final criterion makes the selection easier: we want the radiation to be inexpensive enough to produce in large quantities. When we consider all these requirements, radio waves turn out to be the best answer. Being the lowest-frequency (and lowest-energy) band of the spectrum, they are not very expensive to produce, and we already use them extensively for communications on Earth. They are not significantly absorbed by interstellar dust and gas. With some exceptions, they easily pass through Earth’s atmosphere and through the atmospheres of the other planets we are acquainted with.

### The Cosmic Haystack

Having made the decision that radio is the most likely means of communication among intelligent civilizations, we still have many questions and a daunting task ahead of us. Shall we send a message, or try to receive one? Obviously, if every civilization decides to receive only, then no one will be sending, and everyone will be disappointed. On the other hand, it may be appropriate for us to begin by listening, since we are likely to be among the most primitive civilizations in the Galaxy who are interested in exchanging messages.
We do not make this statement to insult the human species (which, with certain exceptions, we are rather fond of). Instead, we base it on the fact that humans have had the ability to receive (or send) a radio message across interstellar distances for only a few decades. Compared to the ages of the stars and the Galaxy, this is a mere instant. If there are civilizations out there that are ahead of us in development by even a short time (in the cosmic sense), they are likely to have a technology head start of many, many years.
In other words, we, who have just started, may well be the “youngest” species in the Galaxy with this capability (see the discussion in ). Just as the youngest members of a community are often told to be quiet and listen to their elders for a while before they say something foolish, so may we want to begin our exercise in extraterrestrial communication by listening.
Even restricting our activities to listening, however, leaves us with an array of challenging questions. For example, if an extraterrestrial civilization’s signal is too weak to be detected by our present-day radio telescopes, we will not detect them. In addition, it would be very expensive for an extraterrestrial civilization to broadcast on a huge number of channels. Most likely, they select one or a few channels for their particular message. Communicating on a narrow band of channels also helps distinguish an artificial message from the radio static that comes from natural cosmic processes. But the radio band contains an astronomically large number of possible channels. How can we know in advance which one they have selected, and how they have coded their message into the signal?
 summarizes these and other factors that scientists must grapple with when trying to tune in to radio messages from distant civilizations. Because their success depends on either guessing right about so many factors or searching through all the possibilities for each factor, some scientists have compared their quest to looking for a needle in a haystack. Thus, they like to say that the list of factors in  defines the cosmic haystack problem.

### Radio Searches

Although the cosmic haystack problem seems daunting, many other research problems in astronomy also require a large investment of time, equipment, and patient effort. And, of course, if we don’t search, we’re sure not to find anything.
The very first search was conducted by astronomer Frank Drake in 1960, using the 85-foot antenna at the National Radio Astronomy Observatory (). Called Project Ozma, after the queen of the exotic Land of Oz in the children’s stories of L. Frank Baum, his experiment involved looking at about 7200 channels and two nearby stars over a period of 200 hours. Although he found nothing, Drake demonstrated that we had the technology to do such a search, and set the stage for the more sophisticated projects that followed.
Receivers are constantly improving, and the sensitivity of SETI programs—SETI stands for the search for extraterrestrial intelligence—is advancing rapidly. Equally important, modern electronics and software allow simultaneous searches on millions of frequencies (channels). If we can thus cover a broad frequency range, the cosmic haystack problem of guessing the right frequency largely goes away. One powerful telescope array (funded with an initial contribution from Microsoft founder Paul Allen) that is built for SETI searches is the Allen Telescope in Northern California. Other radio telescopes being used for such searches have included the giant Arecibo radio dish in Puerto Rico (which, sadly, collapsed due to storm damage in late 2020), the recently completed, and even larger, FAST dish in China, and the Green Bank Telescope in West Virginia, which is the largest steerable radio telescope in the world.
In 2015, Silicon Valley investor and philanthropist Yuri Milner donated 100 million dollars to the University of California, Berkeley, to enhance the SETI endeavor for ten years. The project, called Breakthrough: Listen, is enlisting more telescopes around the world in the search and is developing sophisticated artificial intelligence programs to scour the incoming signals for intelligent messages. The aim is to search more stars and more channels than any SETI project so far.
What kind of signals do we hope to pick up? We on Earth are inadvertently sending out a flood of radio signals, dominated by military radar systems. This is a kind of leakage signal, similar to the wasted light energy that is beamed upward by poorly designed streetlights and advertising signs. Could we detect a similar leakage of radio signals from another civilization? The answer is just barely, but only for the nearest stars. For the most part, therefore, current radio SETI searches are looking for beacons, assuming that civilizations might be intentionally drawing attention to themselves or perhaps sending a message to another world or outpost that lies in our direction. Our prospects for success depend on how often civilizations arise, how long they last, and how patient they are about broadcasting their locations to the cosmos.

### SETI outside the Radio Realm

For the reasons discussed above, most SETI programs search for signals at radio wavelengths. But in science, if there are other approaches to answering an unsolved question, we don’t want to neglect them. So astronomers have been thinking about other ways we could pick up evidence for the existence of technologically advanced civilizations.
Recently, technology has allowed astronomers to expand the search into the domain of visible light. You might think that it would be hopeless to try to detect a flash of visible light from a planet given the brilliance of the star it orbits. This is why we usually cannot measure the reflected light of planets around other stars. The feeble light of the planet is simply swamped by the “big light” in the neighborhood. So another civilization would need a mighty strong beacon to compete with their star.
However, in recent years, human engineers have learned how to make flashes of light brighter than the Sun. The trick is to “turn on” the light for a very brief time, so that the costs are manageable. But ultra-bright, ultra-short laser pulses (operating for periods of a billionth of a second) can pack a lot of energy and can be coded to carry a message. We also have the technology to detect such short pulses—not with human senses, but with special detectors that can be “tuned” to hunt automatically for such short bursts of light from nearby stars.
Why would any civilization try to outshine its own star in this way? It turns out that the cost of sending an ultra-short laser pulse in the direction of a few promising stars can be less than the cost of sweeping a continuous radio message across the whole sky. Or perhaps they, too, have a special fondness for light messages because one of their senses evolved using light. Several programs are now experimenting with “optical SETI” searches, which can be done with only a modest telescope. (The term optical here means using visible light.)
If we let our imaginations expand, we might think of other for technosignatures—signs of technology from other civilizations. For example, what if a truly advanced civilization should decide to (or need to) renovate its planetary system to maximize the area for life? It could do so by breaking apart some planets or moons and building a ring of solid material that surrounds or encloses the star and intercepts some or all of its light. This huge artificial ring or sphere might glow very brightly at infrared wavelengths, as the starlight it receives is eventually converted to heat and re-radiated into space. That infrared radiation could be detected by our instruments, and searches for such infrared sources are also underway ().

### Should We Transmit in Addition to Listening?

Our planet has some leakage of radio waves into space, from FM radio, television, military radars, and communication between Earth and our orbiting spacecraft. However, such leakage radiation is still quite weak, and therefore difficult to detect at the distances of the stars, at least with the radio technology we have. So at the present time our attempts to communicate with other civilizations that may be out there mostly involve trying to receive messages, but not sending any ourselves.
Some scientists, however, think that it is inconsistent to search for beacons from other civilizations without announcing our presence in a similar way. (We discussed earlier the problem that if every other civilization confined itself to listening, no one would ever get in touch.) So, should we be making regular attempts at sending easily decoded messages into space? Some scientists warn that our civilization is too immature and defenseless to announce ourselves at this early point in our development. The decision whether to transmit or not turns out to be an interesting reflection of how we feel about ourselves and our place in the universe.
Discussions of transmission also raise the question of who should speak for planet Earth. Today, anyone and everyone can broadcast radio signals, and many businesses, religious groups, and governments do. It would be a modest step for the same organizations to use or build large radio telescopes and begin intentional transmissions that are much stronger than the signals that leak from Earth today. And if we intercept a signal from an alien civilization, then the issue arises whether to reply.
Who should make the decision about whether, when, and how humanity announces itself to the cosmos? Is there freedom of speech when it comes to sending radio messages to other civilizations? Do all the nations of Earth have to agree before we send a signal strong enough that it has a serious chance of being received at the distances of the stars? How our species reaches a decision about these kinds of questions may well be a test of whether or not there is intelligent life on Earth.

### Conclusion

Whether or not we ultimately turn out to be the only intelligent species in our part of the Galaxy, our exploration of the cosmos will surely continue. An important part of that exploration will still be the search for biomarkers from inhabited planets that have not produced technological creatures that send out radio signals. After all, creatures like butterflies and dolphins may never build radio antennas, but we are happy to share our planet with them and would be delighted to find their counterparts on other worlds.
Whether or not life exists elsewhere is just one of the unsolved problems in astronomy that we have discussed in this book. A humble acknowledgment of how much we have left to learn about the universe is one of the fundamental hallmarks of science. This should not, however, prevent us from feeling exhilarated about how much we have already managed to discover, and feeling curious about what else we might find out in the years to come.
Our progress report on the ideas of astronomy ends here, but we hope that your interest in the universe does not. We hope you will keep up with developments in astronomy through media and online, or by going to an occasional public lecture by a local scientist. Who, after all, can even guess all the amazing things that future research projects will reveal about both the universe and our connection with it?

### Key Concepts and Summary

Some astronomers are engaged in the search for extraterrestrial intelligent life (SETI). Because other planetary systems are so far away, traveling to the stars is either very slow or extremely expensive (in terms of energy required). Despite many UFO reports and tremendous media publicity, there is no evidence that any of these are related to extraterrestrial visits. Scientists have determined that the best way to communicate with any intelligent civilizations out there is by using electromagnetic waves, and radio waves seem best suited to the task. So far, they have only begun to comb the many different possible stars, frequencies, signal types, and other factors that make up what we call the cosmic haystack problem. Some astronomers are also undertaking searches for brief, bright pulses of visible light and infrared signatures of huge construction projects by advanced civilizations. If we do find a signal someday, deciding whether to answer and what to answer may be two of the greatest challenges humanity will face.

### For Further Exploration

### Articles

### Astrobiology

Chyba, C. “The New Search for Life in the Universe.” Astronomy (May 2010): 34. An overview of astrobiology and the search for life out there in general, with a brief discussion of the search for intelligence.
Dorminey, B. “A New Way to Search for Life in Space.” Astronomy (June 2014): 44. Finding evidence of photosynthesis on other worlds.
McKay, C., & Garcia, V. “How to Search for Life on Mars.” Scientific American (June 2014): 44–49. Experiments future probes could perform.
Reed, N. “Why We Haven’t Found Another Earth Yet.” Astronomy (February 2016): 25. On the search for smaller earthlike planets in their star’s habitable zones, and where we stand.
Shapiro, R. “A Simpler Origin of Life.” Scientific American (June 2007): 46. New ideas about what kind of molecules formed first so life could begin.
Simpson, S. “Questioning the Oldest Signs of Life.” Scientific American (April 2003): 70. On the difficulty of interpreting biosignatures in rocks and the implications for the search for life on other worlds.

### SETI

Chandler, D. “The New Search for Alien Intelligence.” Astronomy (September 2013): 28. Review of various ways of finding other civilizations out there, not just radio wave searches.
Crawford, I. “Where Are They?” Scientific American (July 2000): 38. On the Fermi paradox and its resolutions, and on galactic colonization models.
Folger, T. “Contact: The Day After.” Scientific American (January 2011): 40–45. Journalist reports on efforts to prepare for ET signals; protocols and plans for interpreting messages; and discussions of active SETI.
Kuhn, J., et al. “How to Find ET with Infrared Light.” Astronomy (June 2013): 30. On tracking alien civilizations by the heat they put out.
Lubick, N. “An Ear to the Stars.” Scientific American (November 2002): 42. Profile of SETI researcher Jill Tarter.
Nadis, S. “How Many Civilizations Lurk in the Cosmos?” Astronomy (April 2010): 24. New estimates for the terms in the Drake equation.
Shostak, S. “Closing in on E.T.” Sky & Telescope (November 2010): 22. Nice summary of current and proposed efforts to search for intelligent life out there.

### Websites

### Astrobiology

Astrobiology Web: http://astrobiology.com/. A news site with good information and lots of material.
Exploring Life’s Origins: http://exploringorigins.org/index.html. A website for the Exploring Origins Project, part of the multimedia exhibit of the Boston Museum of Science. Explore the origin of life on Earth with an interactive timeline, gain a deeper knowledge of the role of RNA, “build” a cell, and explore links to learn more about astrobiology and other related information.
History of Astrobiology: https://astrobiology.nasa.gov/about/history-of-astrobiology/. By Marc Kaufman, on the NASA Astrobiology site.
Life, Here and Beyond: https://astrobiology.nasa.gov/about/. By Marc Kaufman, on the NASA Astrobiology site.

### SETI

Berkeley SETI Research Center: https://seti.berkeley.edu/. The University of California group has received a $100 million grant from a Russian-American billionaire to begin the Breakthrough: Listen project, a major step forward in the number of stars and number of radio channels being searched.
Fermi Paradox: https://www.seti.org/fermi-paradox-0. If the Galaxy is teeming with advanced intelligent life, physicist Fermi asked, why is no one visiting us? This is an introduction; the much longer Wikipedia page on this topic (https://en.wikipedia.org/wiki/Fermi_paradox) has more detailed ideas.
Planetary Society: http://www.planetary.org/explore/projects/seti/. This advocacy group for exploration has several pages devoted to the search for life.
Reading list: http://bit.ly/ufoskeptic. If you would like to see the perspective of scientists and other skeptical investigators on UFO controversies, check out this reading list.
SETI Institute: http://www.seti.org. A key organization in the search for life in the universe; the institute’s website is full of information and videos about both astrobiology and SETI.
SETI: http://www.skyandtelescope.com/tag/seti/. Sky & Telescope magazine offers good articles on this topic.

### Videos

### Astrobiology

Copernicus Complex: Are We Special in the Cosmos?: https://www.youtube.com/watch?v=ERp0AHYRm_Q. A video of a popular-level talk by Caleb Scharf of Columbia University (1:18:54).
Life at the Edge: Life in Extreme Environments on Earth and the Search for Life in the Universe: https://www.youtube.com/watch?v=91JQmTn0SF0. A video of a 2009 nontechnical lecture by Lynn Rothschild of NASA Ames Research Center (1:31:21).
Saturn’s Moon Titan: A World with Rivers, Lakes, and Possibly Even Life: https://www.youtube.com/watch?v=bbkTJeHoOKY. A video of a 2011 talk by Chris McKay of NASA Ames Research Center (1:23:33).

### SETI

Allen Telescope Array: The Newest Pitchfork for Exploring the Cosmic Haystack: https://www.youtube.com/watch?v=aqsI1HZCgUM. A 2013 popular-level lecture by Jill Tarter of the SETI Institute (1:45:55).
Search for Extra-Terrestrial Intelligence: Necessarily a Long-Term Strategy: http://www.longnow.org/seminars/02004/jul/09/the-search-for-extra-terrestrial-intelligence-necessarily-a-long-term-strategy/. 2004 talk by Jill Tarter at the Long Now Foundation (1:21:13).
The Search for Extra-Terrestrial Life with New Generation Technology: https://www.youtube.com/watch?v=R1ndk08vZqM. A briefing in 2020 with Jill Tarter, Andrew Siemion, and Victoria Meadows on how scientists are currently searching for life, including intelligent life.
Search for Intelligent Life Among the Stars: New Strategies: https://www.youtube.com/watch?v=m9WxW2ktcKU. A 2010 nontechnical talk by Seth Shostak of the SETI Institute (1:29:58).
The Breakthrough: Listen Initiative—Our Boldest Effort to Answer our Oldest Question: https://www.youtube.com/watch?v=vQ2sKwwhRgI. A talk by Andrew Siemion at Harvard, with some nontechnical and some more technical sections.

### Collaborative Group Activities

1. If one of the rocks from Mars examined by a future mission to the red planet does turn out to have unambiguous signs of ancient life that formed on Mars, what does your group think would be the implications of such a discovery for science and for our view of life elsewhere? Would such a discovery have any long-term effects on your own thinking?
2. Suppose we receive a message from an intelligent civilization around another star. What does your group think the implications of this discovery would be? How would your own thinking or personal philosophy be affected by such a discovery?
3. A radio message has been received from a civilization around a star 40 light-years away, which contains (in pictures) quite a bit of information about the beings that sent the message. The president of the United States has appointed your group a high-level commission to advise whether humanity should answer the message (which was not particularly directed at us, but comes from a beacon that, like a lighthouse, sweeps out a circle in space). How would you advise the president? Does your group agree on your answer or do you also have a minority view to present?
4. If there is no evidence that UFOs are extraterrestrial visitors, why does your group think that television shows, newspapers, and movies spend so much time and effort publicizing the point of view that UFOs are craft from other worlds? Make a list of reasons. Who stands to gain by exaggerating stories of unknown lights in the sky or simply fabricating stories that alien visitors are already here?
5. Does your group think scientists should simply ignore all the media publicity about UFOs or should they try to respond? If so, how should they respond? Does everyone in the group agree?
6. Suppose your group is the team planning to select the most important sights and sounds of Earth to record and put on board the next interstellar spacecraft. What pictures (or videos) and sounds would you include to represent our planet to another civilization?
7. Let’s suppose Earth civilization has decided to broadcast a message announcing our existence to other possible civilizations among the stars. Your group is part of a large task force of scientists, communications specialists, and people from the humanities charged with deciding the form and content of our message. What would you recommend? Make a list of ideas.
8. Think of examples of contact with aliens you have seen in movies and on TV. Discuss with your group how realistic these have been, given what you have learned in this class. Was the contact in person (through traveling) or using messages? Why do you think Hollywood does so many shows and films that are not based on our scientific understanding of the universe?
9. Go through the Drake equation with your group and decide on values for each factor in the estimate. (If you disagree on what a factor should be within the group, you can have a “minority report.”) Based on the factors, how many intelligent, communicating civilizations do you estimate to be thriving in our Galaxy right now?

### Review Questions

### Thought Questions

### Figuring for Yourself


# Setting the Stage

## Unit Introduction

Welcome to Principles of Marketing! Some people may mistakenly believe that marketing skills can only be applied to marketing tasks, but the fact is that marketing isn’t only for marketers. Studying marketing is essential in almost any career field, because it teaches you the basic principles that connect people, brands, and businesses.
This textbook is divided into three units:
1. Unit 1: Setting the Stage
2. Unit 2: Understanding the Marketplace
3. Unit 3: Product, Promotion, Price, and Place
In this first section, we’re going to set the stage for the remainder of this textbook, by first exploring marketing as a discipline and understanding the concept of customer value. Then we’ll analyze the role of strategic planning in marketing, because strategy defines how you communicate that customer value to others.


# Understanding the Marketplace

## Unit Introduction

Welcome to Unit 2 of Principles of Marketing. In Unit 1, the stage was set for studying marketing. Unit 2 discusses the analytical tools and frameworks to understand a broad range of customers (whether consumers or businesses) and categorize them into target markets. It then reviews marketing research techniques used to gather data and make sound marketing decisions. Finally, the last two chapters of this unit emphasize the challenges of expanding to international markets and reaching culturally and demographically diverse segments in domestic markets.


# Product, Promotion, Price, and Place

## Unit Introduction

In this last unit, we will be exploring next-level marketing concepts. We will look at product marketing, services marketing, pricing, integrated marketing communications, the promotion mix, social media marketing, distribution, retailing and wholesaling, and sustainability.
Enjoy the topics and their corresponding examples!


# Wstęp do psychologii

## Wprowadzenie

Clive Wearing (ur. 1938), uznany muzyk, utracił umiejętność tworzenia nowych wspomnień w wyniku choroby, na którą zapadł w wieku 46 lat. O ile mężczyzna nadal potrafi bezbłędnie grać na pianinie, to nie jest w stanie zapamiętać, co jadł na śniadanie zaledwie kilka godzin wcześniej (Sacks, 2007). James Wannerton przeżywa doznania zmysłowe powiązane z dźwiękiem słów. Imię jego byłej dziewczyny smakuje według niego jak rabarbar (Mundasad, 2013). John Nash (1928-2015) to wybitny matematyk i laureat nagrody Nobla. Mimo piastowania funkcji profesora na  (MIT) zwykł opowiadać innym, że w artykułach publikowanych w „” zakodowane są wiadomości od istot pozaziemskich skierowane do niego. Naukowiec zaczął również słyszeć głosy i stał się podejrzliwy wobec otaczających go ludzi. Wkrótce po tym u Nasha zdiagnozowano schizofrenię i został on przyjęty do państwowego szpitala psychiatrycznego (O’Connor i Robertson, 2002). Nash był bohaterem filmu z 2001 roku pt. Piękny umysł. Dlaczego te wszystkie osoby miały takie doświadczenia? Jak działa ludzki mózg? Jakie powiązania istnieją między wewnętrznymi procesami zachodzącymi w mózgu a zachowaniami danej osoby? Podręcznik Psychologia omawia szereg sposobów, w jakie dziedzina psychologii bada tego typu problemy.

### References

American Board of Forensic Psychology. (2014). Brochure. Pobrane z: http://www.abfp.com/brochure.asp.
American Psychological Association. (2014). Pobrane z: www.apa.org.
American Psychological Association. (2014). Graduate training and career possibilities in exercise and sport psychology. Pobrane z: http://www.apadivisions.org/division-47/about/resources/training.aspx?item=1.
American Psychological Association. (2019). Maime Phipps Clark, PhD, and Kenneth Clark, PhD. Pobrane z: https://www.apa.org/pi/oema/resources/ethnicity-health/psychologists/clark.
American Psychological Association. (2011). Psychology as a career. Pobrane z: http://www.apa.org/education/undergrad/psych-career.aspx.
Ashliman, D. L. (2001). Cupid and Psyche. In Folktexts: A library of folktales, folklore, fairy tales, and mythology. Pobrane z: http://www.pitt.edu/~dash/cupid.html.
Betancourt, H., & López, S. R. (1993). The study of culture, ethnicity, and race in American psychology. American Psychologist, 48, 629–637.
Black, S. R., Spence, S. A., Omari, S. R. (2004). Contributions of African Americans to the field of psychology. Journal of Black Studies, 35, 40–64.
Bulfinch, T. (1855). The age of fable: Or, stories of gods and heroes. Boston, MA: Chase, Nichols and Hill.
Buss, D. M. (1989). Sex differences in human mate preferences: Evolutionary hypotheses tested in 37 cultures. Behavioral and Brain Sciences, 12, 1–49.
Carlson, N. R. (2013). Physiology of Behavior (11th ed.). Boston, MA: Pearson.
Confer, J. C., Easton, J. A., Fleischman, D. S., Goetz, C. D., Lewis, D. M. G., Perilloux, C., Buss, D. M. (2010). Evolutionary psychology. Controversies, questions, prospects, and limitations. American Psychologist, 65, 100–126.
Crawford, M., Marecek, J. (1989). Psychology reconstructs the female 1968–1988. Psychology of Women Quarterly, 13, 147–165.
Danziger, K. (1980). The history of introspection reconsidered. Journal of the History of the Behavioral Sciences, 16, 241–262.
Darwin, C. (1871). The descent of man and selection in relation to sex. London: John Murray.
Darwin, C. (1872). The expression of the emotions in man and animals. London: John Murray.
DeAngelis, T. (2010). Fear not. gradPSYCH Magazine, 8, 38.
Department of Health and Human Services. (n.d.). Projected future growth of the older population. Pobrane z: http://www.aoa.gov/Aging_Statistics/future_growth/future_growth.aspx#age.
Endler, J. A. (1986). Natural Selection in the Wild. Princeton, NJ: Princeton University Press.
Fogg, N. P., Harrington, P. E., Harrington, T. F., & Shatkin, L. (2012). College majors handbook with real career paths and payoffs (3rd ed.). St. Paul, MN: JIST Publishing.
Franko, D. L., et al. (2012). Racial/ethnic differences in adults in randomized clinical trials of binge eating disorder. Journal of Consulting and Clinical Psychology, 80, 186–195.
Friedman, H. (2008), Humanistic and positive psychology: The methodological and epistemological divide. The Humanistic Psychologist, 36, 113–126.
Główny Urząd Statystyczny. Ludność. stan i struktura ludności oraz ruch naturalny w przekroju terytorialnym (stan w dniu 31.12.2019). Publikacja 30.04.2020.
Gordon, O. E. (1995). A brief history of psychology. Pobrane z: http://www.psych.utah.edu/gordon/Classes/Psy4905Docs/PsychHistory/index.html#maptop.
Green, C. D. (2001). Classics in the history of psychology. Pobrane z: http://psychclassics.yorku.ca/Krstic/marulic.htm.
Greengrass, M. (2004). 100 years of B.F. Skinner. Monitor on Psychology, 35, 80.
Hock, R. R. (2009). Social psychology. Forty studies that changed psychology: Explorations into the history of psychological research (pp. 308–317). Upper Saddle River, NJ: Pearson.
Hoffman, C. (2012). Careers in clinical, counseling, or school psychology; mental health counseling; clinical social work; marriage & family therapy and related professions. Pobrane z: http://www.indiana.edu/~psyugrad/advising/docs/Careers%20in%20Mental%20Health%20Counseling.pdf.
Ignaszak, M. (2016). Jak zostać psychologiem klinicznym? Pobrane z: http://pytaniaiodpowiedzi.pl/jak-zostac-psychologiem-klinicznym/.
Jang, K. L., Livesly, W. J., Vernon, P. A. (1996). Heritability of the Big Five personality dimensions and their facets: A twin study. Journal of Personality, 64, 577–591.
Knekt, P. P., Lindfors, O., Härkänen, T., Välikoski, M., Virtala, E., Laaksonen, M. A., Marttunen, M., Kaipainen, M., Renlund, C.; Helsinki Psychotherapy Study Group. (2008). Randomized trial on the effectiveness of long- and short-term psychodynamic psychotherapy and solution-focused therapy on psychiatric symptoms during a 3-year follow-up. Psychological Medicine: A Journal of Research In Psychiatry And The Allied Sciences, 38, 689–703.
Landers, R. N. (2011, June 14). Grad school: Should I get a PhD or Master’s in I/O psychology? [Web log post]. Pobrane z: http://neoacademic.com/2011/06/14/grad-school-should-i-get-a-ph-d-or-masters-in-io-psychology/#.UuKKLftOnGg.
Macdonald, C. (2013). Health psychology center presents: What is health psychology? Pobrane z: http://healthpsychology.org/what-is-health-psychology/.
McCrae, R. R., Costa, P. T. (2008). Empirical and theoretical status of the five-factor model of personality traits. W: G. J. Boyle, G. Matthews, D. H. Saklofske (red.). The Sage handbook of personality theory and assessment. Vol. 1.Personality theories and models. London: Sage.
Michalski, D., Kohout, J., Wicherski, M., Hart, B. (2011). 2009 Doctorate Employment Survey. APA Center for Workforce Studies. Pobrane z: http://www.apa.org/workforce/publications/09-doc-empl/index.aspx.
Miller, G. A. (2003). The cognitive revolution: A historical perspective. Trends in Cognitive Sciences, 7, 141–144.
Ministerstwo Nauki i Szkolnictwa Wyższego, Biuletyn Informacji Publicznej (2019). Pobrane z: http://www.bip.nauka.gov.pl/komunikaty-rzecznika-prasowego-mnisw/znamy-ranking-najpopularniejszych-kierunkow-studiow-w-roku-akademickim-2018-2019.html.
Munakata, Y., McClelland, J. L., Johnson, M. H., Siegler, R. S. (1997). Rethinking infant knowledge: Toward an adaptive process account of successes and failures in object permanence tasks. Psychological Review, 104, 689–713.
Mundasad, S. (2013). Word-taste synaesthesia: Tasting names, places, and Anne Boleyn. Pobrane z: http://www.bbc.co.uk/news/health-21060207
Munsey, C. (2009). More states forgo a postdoc requirement. Monitor on Psychology, 40, 10.
Najpopularniejsze kierunki studiów 2019.Rzeczpospolita, Pobrane z: https://www.rp.pl/Edukacja-i-wychowanie/307129976-Najpopularniejsze-kierunki-studiow-2019.html.
National Association of School Psychologists. (n.d.). Becoming a nationally certified school psychologist (NCSP). Pobrane z: http://www.nasponline.org/CERTIFICATION/becomeNCSP.aspx.
Nicolas, S., & Ferrand, L. (1999). Wundt’s laboratory at Leipzig in 1891. History of Psychology, 2, 194–203.
Norcross, J. C. (n.d.) Clinical versus counseling psychology: What’s the diff? Pobrane z: http://www.csun.edu/~hcpsy002/Clinical%20Versus%20Counseling%20Psychology.pdf.
Norcross, J. C., Castle, P. H. (2002). Appreciating the PsyD: The facts. Eye on Psi Chi, 7, 22–26.
O'Connor, J. J., Robertson, E. F. (2002) John Forbes Nash. Press.
O’Hara, M. (n.d.). Historic review of humanistic psychology. Pobrane z: http://www.ahpweb.org/index.php?option=com_k2&view=item&layout=item&id=14&Itemid=24.
Person, E. S. (1980). Sexuality as the mainstay of identity: Psychoanalytic perspectives. Signs, 5, 605–630.
Rantanen, J., Metsäpelto, R. L., Feldt, T., Pulkkinen, L., Kokko, K. (2007). Long-term stability in the Big Five personality traits in adulthood. Scandinavian Journal of Psychology, 48, 511–518.
Riggio, R. E. (2013). What is industrial/organizational psychology? Psychology Today. Pobrane z: http://www.psychologytoday.com/blog/cutting-edge-leadership/201303/what-is-industrialorganizational-psychology.
Sacks, O. (2007). A neurologists notebook: The abyss, music and amnesia. The New Yorker. Pobrane z: http://www.newyorker.com/reporting/2007/09/24/070924fa_fact_sacks?currentPage=all.
Schnyder, U., Bryant, R. A., Ehlers, A., Foa, E. B., Hasan, A., Mwiti, G., Kristensen, Ch. H., Neuner, F., Oe, M., Yule, W. (2016). Culture-sensitive psychotraumatology. European Journal of Psychotraumatology, 7, doi: 10.3402/ejpt.v7.31179.
Shedler, J. (2010). The efficacy of psychodynamic psychotherapy. American Psychologist, 65(2), 98–109.
Soldz, S., Vaillant, G. E. (1999). The Big Five personality traits and the life course: A 45-year longitudinal study. Journal of Research in Personality, 33, 208–232.
Thorne, B. M., Henley, T. B. (2005). Connections in the history and systems of psychology (3rd ed.). Boston, MA: Houghton Mifflin Company.
Ustawa z dnia 8 czerwca 2001 „o zawodzie psychologa i samorządzie zawodowym psychologów. Pobrane z: http://prawo.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=WDU20010730763.
Ustawa z dnia 11 września 2015 r. o zdrowiu publicznym. Pobrane z: http://prawo.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=WDU20150001916.
Watson, J. B. (1913). Psychology as the behaviorist views it. Psychological Review, 20, 158-177.
Weisstein, N. (1993). Psychology constructs the female: Or, the fantasy life of the male psychologist (with some attention to the fantasies of his friends, the male biologist and the male anthropologist). Feminism and Psychology, 3, 195–210.
Westen, D. (1998). The scientific legacy of Sigmund Freud, toward a psychodynamically informed psychological science. Psychological Bulletin, 124, 333–371.
Vogels, S. R. (2014). The Milgram experiment: Its impact and interpretation. Social Cosmos, 5(1), 15 - 21.
Volkmann-Raue, S, Luck, H. E. (2014). Najwybitniejsze kobiety w psychologii XX wieku. Gdańsk: GWP Gdańskie Wydawnictwo Psychologiczne.


# Wstęp do psychologii

## Czym jest psychologia

Skąd się bierze kreatywność? Dlaczego niektórzy zostają dotknięci bezdomnością? Czym są uprzedzenia i dyskryminacja? Co to jest świadomość? Psycholodzy zajmują się poszukiwaniem odpowiedzi na tego typu pytania, prowadząc badania naukowe nad umysłowością i zachowaniami. Pierwszym krokiem metody naukowej jest postawienie hipotezy będącej próbą wyjaśnienia badanego zagadnienia. Hipoteza powinna wpisywać się w teorię naukową, która jest aktualnym i zweryfikowanym licznymi badaniami zbiorem ustaleń dotyczących określonego obszaru wiedzy. Badacz następnie przeprowadza obserwację lub eksperyment, mające sprawdzić trafność hipotezy. Wynik i analiza badań są publikowane lub prezentowane podczas konferencji naukowej po to, by inni badacze mogli, po pierwsze: zreplikować wyniki otrzymane przez badacza (i tym samym sprawdzić poprawność procesu badawczego), a po drugie: by mogli wykorzystać je w swoich badaniach. Naukowcy badają to, co jest mierzalne. Na przykład hipoteza, że ptak śpiewa, ponieważ jest szczęśliwy, nie może być sprawdzona w sposób naukowy, ponieważ nie potrafimy zmierzyć poziomu szczęścia ptaka. Należy wówczas zadać inne pytanie, na przykład o aktywność określonego obszaru mózgu ptaka, ponieważ ją potrafimy zmierzyć dostępnymi metodami. Jeśli tę samą hipotezę zastosujemy do ludzi („śpiewają, gdy czują się szczęśliwi”), będzie ona dobrym punktem wyjścia do badania naukowego, ponieważ możemy o poczuciu szczęścia porozmawiać z badaną jednostką.
Metody naukowe pozwalają zbadać wyłącznie zjawiska mierzalne, nie ma zaś możliwości zdobycia wiedzy na temat wartości czy moralności. To jeden z powodów, dla których naukowe rozumienie umysłu podlega ograniczeniom – wszak myśli, czy też sposobu ich przeżywania, nie da się bezpośrednio „złapać” ani zmierzyć. Metoda naukowa opiera się na metodzie empirycznej. Metoda empiryczna (ang. ) polega na obserwacji i prowadzeniu eksperymentów; w odróżnieniu od metod opartych wyłącznie na formach argumentacji logicznej lub teorii ukutych przez wcześniejszych badaczy (obecnych np. w takich naukach jak logika, matematyka etc.).
Psychologia została uznana za niezależną dziedzinę nauki pod koniec XIX wieku. Wcześniej zagadnienia dotyczące funkcjonowania umysłu były domeną filozofii. W związku z tym, że u źródeł każdego zachowania leży uwarunkowanie biologiczne, określone obszary psychologii zalicza się do nauk przyrodniczych, takich jak biologia. Żaden organizm biologiczny nie funkcjonuje samodzielnie, w izolacji od otoczenia, a na nasze zachowanie wpływ mają interakcje z innymi. Dlatego też psychologię zalicza się również do nauk społecznych.

### Dlaczego warto uczyć się psychologii?

Niekiedy studenci po raz pierwszy wybierają zajęcia z psychologii, bo są zainteresowani pomocą innym i chcą dowiedzieć się więcej o sobie samych - dlaczego zachowują się w określony sposób. Inni studenci decydują się na takie zajęcia, bo są zobowiązani do zaliczenia puli zajęć ogólnouniwersyteckich. Wiele osób psychologia tak wciąga, że ostatecznie wybierają ją jako główny przedmiot swoich studiów.
Studia psychologiczne od wielu lat cieszą się w Polsce niesłabnącą popularnością. W 2019 roku o przyjęcie na studia z psychologii na Uniwersytecie Warszawskim ubiegało się 2,4 tys. kandydatów, o jedno miejsce rywalizowało 15 osób. Dla porównania, na Uniwersytecie Jagiellońskim było 1799 kandydatów (osiem osób na miejsce), na Uniwersytecie Łódzkim 1100 (11 osób na miejsce), na Uniwersytecie Adama Mickiewicza w Poznaniu 1705 osób (11 osób na miejsce) („Rzeczpospolita”, 2019). Zgodnie z danymi Ministerstwa Nauki i Szkolnictwa Wyższego (2019) psychologia uplasowała się na trzecim miejscu jako najchętniej wybierany kierunek (po informatyce i zarządzaniu).
Wykształcenie psychologiczne przydaje się w wielu obszarach. Studenci psychologii zdobywają umiejętność krytycznego myślenia i praktycznego stosowania metod naukowych. Myślenie krytyczne to umiejętność zdystansowanego podejścia i wykorzystania wiedzy naukowej w analizie informacji. Ocena wartości informacji – jej wiarygodności i przydatności – to niezwykle ważna umiejętność we współczesnym świecie obfitującym w mnogość (jeśli nie nadmiar) danych. Część tych informacji jest niedopowiedziana albo celowo przeinaczona (tzw. ) dla wywołania określonego efektu u odbiorcy (np. niepewności) i uzyskania określonych celów (politycznych, marketingowych etc.).
Umiejętność myślenia krytycznego pozwala spojrzeć na dane zagadnienie sceptycznie, rozpoznać sprzeczności poprzez wykorzystanie logiki, zadawanie odpowiednich pytań i obserwację.
Dzięki nauce psychologii studenci są w stanie zrozumieć złożone czynniki wpływające na nasze zachowanie. Są oni w stanie rozróżnić wpływ genów, środowiska i doświadczenia na zachowanie człowieka. Tym samym mogą sprawdzić się jako przyszli specjaliści w wielu dziedzinach: marketingu, pomocy psychologicznej, pracy wychowawczej, resocjalizacyjnej itd.

### Podsumowanie

Termin „psychologia” wywodzi się z wyrazów psyche (oznaczającego duszę) i logos (oznaczającego naukę o danej dziedzinie). W związku z tym psychologię definiuje się jako naukę o umyśle i zachowaniach. Studenci psychologii uczą się myślenia krytycznego, poznają działanie i zastosowanie w praktyce metod naukowych oraz są w stanie zauważyć różnorodność ludzkich zachowań i ich przyczyny.

### Review Questions

### Critical Thinking Questions

### Personal Application Question