Who did discover the expanding universe? - Health & Science - Jerusalem Post Who did discover the expanding universe? BySPACE TELESCOPE SCIENCE INSTITUTE (STSCI) 20 November 2011 14:40 For nearly a century, Edwin P. Hubble has held the fame for this landmark discovery, which would recast all of 20th century astronomy. The Hubble space telescope 311. (photo credit:NASA) The greatest astronomical discovery of the 20th century may have been credited to the wrong person. But it turns out to have been nobody's fault except for that of the actual original discoverer himself. Writing in the November 10th issue of the journal Nature, astrophysicist Mario Livio of the Space Telescope Science Institute has put to bed a growing conspiracy theory about who was fairly credited for discovering the expanding universe. Be the first to know - Join our Facebook page. For nearly a century, American astronomer Edwin P. Hubble has held the fame for this landmark discovery, which would recast all of 20th century astronomy. Hubble reported that the universe is uniformly expanding in all directions.

It solved Einstein's dilemma of explaining why the universe didn't already collapse under its own gravity. Ironically, Hubble never got a Nobel Prize for this discovery, though astronomers from two teams who independently uncovered evidence for an accelerating universe won the 2011 Noble Prize in Physics. But Hubble did get the most celebrated telescope of modern history named after him. Hubble published his landmark paper in which he determined the rate of expansion of the universe in 1929. This was based on the apparent recessional velocities (deduced from redshifts) of galaxies, as previously measured by astronomer Vesto Slipher, coupled to distances to the same galaxies, as determined by Hubble. Hubble's analysis showed that the farther the galaxy was, the faster it appeared to be receding. The rate of cosmic expansion is now known as the Hubble Constant. But two years earlier, a Belgian priest and cosmologist, Georges Lemaître, published very similar conclusions, and he calculated a rate of expansion similar to what Hubble would publish two years later. Lemaître based his analysis on Slipher's same redshift data, which he combined with estimates of galaxy distances inferred from Hubble's 1926 published observations.

But Lemaître's discovery went unnoticed because it was published in French, in a rather obscure Belgian science journal called the Annales de la Société Scientifique de Bruxelles (Annals of the Brussels Scientific Society). The story would have ended there, except that Lemaître's work was later translated and published in the Monthly Notices of the Royal Astronomical Society. When published in 1931, some of Lemaître's own calculations from 1927, of what would be later called the Hubble Constant, were omitted! The fact that paragraphs were missing from the translated paper has been known (although not widely) since 1984. There has been persistent speculation among astronomers over "who dunnit?" Did the Monthly Notices editors cut the paragraphs out? Did Edwin Hubble himself have an influencing hand and censor the paper to eliminate any doubt that he was the original discoverer of the expanding universe? After going through hundreds of pieces of correspondence of the Royal Astronomical Society, as well as minutes of the RAS meetings, and material from the Lemaître Archive, Livio has discovered that Lemaître omitted the passages himself when he translated the paper into English!

In one of two "smoking-gun letters" uncovered by Livio, Lemaître wrote to the editors: "I did not find advisable to reprint the provisional discussion of radial velocities which is clearly of no actual interest, and also the geometrical note, which could be replaced by a small bibliography of ancient and new papers on the subject." The remaining question is why Lemaître essentially erased evidence for credit due to him, for first discovering (at least tentatively) the expanding universe. Livio concludes, "Lemaître's letter also provides an interesting insight into the scientific psychology of some of the scientists of the 1920s. Lemaître was not at all obsessed with establishing priority for his original discovery. Given that Hubble's results had already been published in 1929, he saw no point in repeating his more tentative earlier findings again in 1931." Perhaps in some alternative history parallel universe, people are marveling at the deep-space pictures from the Lemaître Space Telescope. Relevant to your professional network? Please share on Linkedin Tags: The Expanding Universe Modern Cosmology The Expanding Universe For thousands of years, astronomers wrestled with basic questions about the size and age of the universe.

Does the universe go on forever, or does it have an edge somewhere? Has it always existed, or did it come to being some time in the past? In 1929, Edwin Hubble, an astronomer at Caltech, made a critical discovery that soon led to scientific answers for these questions: he discovered that the universe is expanding. The ancient Greeks recognized that it was difficult to imagine what an infinite universe might look like. But they also wondered that if the universe were finite, and you stuck out your hand at the edge, where would your hand go? The Greeks' two problems with the universe represented a paradox - the universe had to be either finite or infinite, and both alternatives presented problems. After the rise of modern astronomy, another paradox began to puzzle astronomers. In the early 1800s, German astronomer Heinrich Olbers argued that the universe must be finite. If the Universe were infinite and contained stars throughout, Olbers said, then if you looked in any particular direction, your line-of-sight would eventually fall on the surface of a star. Although the apparent size of a star in the sky becomes smaller as the distance to the star increases, the brightness of this smaller surface remains a constant.

Therefore, if the Universe were infinite, the whole surface of the night sky should be as bright as a star. Obviously, there are dark areas in the sky, so the universe must be finite. But, when Isaac Newton discovered the law of gravity, he realized that gravity is always attractive. Every object in the universe attracts every other object. If the universe truly were finite, the attractive forces of all the objects in the universe should have caused the entire universe to collapse on itself. This clearly had not happened, and so astronomers were presented with a paradox. When Einstein developed his theory of gravity in the General Theory of Relativity, he thought he ran into the same problem that Newton did: his equations said that the universe should be either expanding or collapsing, yet he assumed that the universe was static. His original solution contained a constant term, called the cosmological constant, which cancelled the effects of gravity on very large scales, and led to a static universe. After Hubble discovered that the universe was expanding, Einstein called the cosmological constant his "greatest blunder." At around the same time, larger telescopes were being built that were able to accurately measure the spectra, or the intensity of light as a function of wavelength, of faint objects.

Using these new data, astronomers tried to understand the plethora of faint, nebulous objects they were observing. Between 1912 and 1922, astronomer Vesto Slipher at the Lowell Observatory in Arizona discovered that the spectra of light from many of these objects was systematically shifted to longer wavelengths, or redshifted. A short time later, other astronomers showed that these nebulous objects were distant galaxies. The Discovery of the Expanding Universe Meanwhile, other physicists and mathematicians working on Einstein's theory of gravity discovered the equations had some solutions that described an expanding universe. In these solutions, the light coming from distant objects would be redshifted as it traveled through the expanding universe. The redshift would increase with increasing distance to the object. Edwin Hubble In 1929 Edwin Hubble, working at the Carnegie Observatories in Pasadena, California, measured the redshifts of a number of distant galaxies. He also measured their relative distances by measuring the apparent brightness of a class of variable stars called Cepheids in each galaxy. When he plotted redshift against relative distance, he found that the redshift of distant galaxies increased as a linear function of their distance.

The only explanation for this observation is that the universe was expanding. Once scientists understood that the universe was expanding, they immediately realized that it would have been smaller in the past. At some point in the past, the entire universe would have been a single point. This point, later called the big bang, was the beginning of the universe as we understand it today. The expanding universe is finite in both time and space. The reason that the universe did not collapse, as Newton's and Einstein's equations said it might, is that it had been expanding from the moment of its creation. The universe is in a constant state of change. The expanding universe, a new idea based on modern physics, laid to rest the paradoxes that troubled astronomers from ancient times until the early 20th Century. Properties of the Expanding Universe The equations of the expanding universe have three possible solutions, each of which predicts a different eventual fate for the universe as a whole. Which fate will ultimately befall the universe can be determined by measuring how fast the universe expands relative to how much matter the universe contains. The three possible types of expanding universes are called open, flat, and closed universes. If the universe were open, it would expand forever.

If the universe were flat, it would also expand forever, but the expansion rate would slow to zero after an infinite amount of time. If the universe were closed, it would eventually stop expanding and recollapse on itself, possibly leading to another big bang. In all three cases, the expansion slows, and the force that causes the slowing is gravity. A simple analogy to understand these three types of universes is to consider a spaceship launched from the surface of the Earth. If the spaceship does not have enough speed to escape the Earth's gravity, it will eventually fall back to Earth. This is analogous with a closed universe that recollapses. If the spaceship is given enough speed so that it has just enough energy to escape, then at an infinite distance away from the Earth, it will come to a stop (this is the flat universe). And lastly, if the ship is launched with more than enough energy to escape, it will always have some speed, even when it is an infinite distance away (the open universe). The Fate of the Universe For the last eighty years, astronomers have been making increasingly accurate measurements of two important cosmological parameters: Ho - the rate at which the universe expands - and w - the average density of matter in the universe.

Knowledge of both of these parameters will tell which of the three models describes the universe we live in, and thus the ultimate fate of our universe. The Sloan Digital Sky Survey, with its large systematic measurement of the galaxy density in the Universe, should enable astronomers to precisely measure the density parameter w. The Heavy Elements Astronomers are not only interested in the fate of the universe; they are also interested in understanding its present physical state. One question they try to answer is why the universe is primarily composed of hydrogen and helium, and what is responsible for the relatively small concentration of the heavier elements. With the rise of nuclear physics in the 1930s and 40s, scientists started to try to explain the abundances of heavier elements by assuming they were synthesized out of primordial hydrogen in the early universe. In the late 1940s, American physicists George Gamow, Robert Herman, and Ralph Alpher realized that long ago, the universe was much hotter and denser. They made calculations to show whether nuclear reactions that took place at those higher temperatures could have created the heavy elements. Unfortunately, with the exception of helium, they found that it was impossible to form heavier elements in any appreciable quantity.

Today, we understand that heavy elements were synthesized either in the cores of stars or during supernovae, when a large dying star implodes. Gamow, Herman, and Alpher did realize, though, that if the universe were hotter and denser in the past, radiation should still be left over from the early universe. This radiation would have a well-defined spectrum (called a blackbody spectrum) that depends on its temperature. As the universe expanded, the spectrum of this light would have been redshifted to longer wavelengths, and the temperature associated with the spectrum would have decreased by a factor of over one thousand as the universe cooled. The Cosmic Microwave Background Radiation In 1963, Arno Penzias and Robert Wilson, two scientists in Holmdale, New Jersey, were working on a satellite designed to measure microwaves. When they tested the satellite's antenna, they found mysterious microwaves coming equally from all directions. At first, they thought something was wrong with the antenna. But after checking and rechecking, they realized that they had discovered something real. What they discovered was the radiation predicted years earlier by Gamow, Herman, and Alpher.

The radiation that Penzias and Wilson discovered, called the Cosmic Microwave Background Radiation, convinced most astronomers that the Big Bang theory was correct. For discovering the Cosmic Microwave Background Radiation, Penzias and Wilson were awarded the 1978 Nobel Prize in Physics. After Penzias and Wilson found the Cosmic Microwave Background Radiation, astrophysicists began to study whether they could use its properties to study what the universe was like long ago. According to Big Bang theory, the radiation contained information on how matter was distributed over ten billion years ago, when the universe was only 500,000 years old. At that time, stars and galaxies had not yet formed. The Universe consisted of a hot soup of electrons and atomic nuclei. These particles constantly collided with the photons that made up the background radiation, which then had a temperature of over 3000 C. Soon after, the Universe expanded enough, and thus the background radiation cooled enough, so that the electrons could combine with the nuclei to form atoms. Because atoms were electrically neutral, the photons of the background radiation no longer collided with them.

When the first atoms formed, the universe had slight variations in density, which grew into the density variations we see today - galaxies and clusters. These density variations should have led to slight variations in the temperature of the background radiation, and these variations should still be detectable today. Scientists realized that they had an exciting possibility: by measuring the temperature variations of the Cosmic Microwave Background Radiation over different regions of the sky, they would have a direct measurement of the density variations in the early universe, over 10 billion years ago. Density Variations in the Early Universe Map of the sky as observed by COBE. The map on the bottom shows the temperature variations of the background radiation. In 1990, a satellite called the Cosmic Microwave Background Explorer (COBE) measured background radiation temperatures over the whole sky. COBE found variations that amounted to only about 5 parts in 100,000, but revealed the density fluctuations in the early universe. The initial density variations would be the seeds of structure that would grow over time to become the galaxies, clusters of galaxies, and superclusters of galaxies observed today by the Sloan Digital Sky Survey.

With the Sloan data, along with data from COBE, astronomers will be able to reconstruct the evolution of structure in the universe over the last 10 to 15 billion years. With this information, we will have a deep understanding of the history of the universe, which will be an almost unbelievable scientific and intellectual achievement. But measuring the evolution of the density variations in the universe still does not answer the most important question: why does the universe contain these differences in density in the first place? To answer this question, astronomers and astrophysicists must understand the nature of the density variations and construct theories of the origin of the universe that predict how these variations should occur. Famous Astronomers | List of Great Scientists in Astronomy Famous Astronomers | List of Great Scientists in Astronomy By Nola Taylor Redd, Space.com Contributor | June 11, 2012 10:07am ET MORE Throughout human history, scientists have struggled to understand what they see in the universe. Famous astronomers — many of them great scientists who mastered many fields — explained the heavens with varying degrees of accuracy.

Over the centuries, a geocentric view of the universe — with Earth at the center of everything — gave way to the proper understanding we have today of an expanding universe in which our galaxy is but one of billions. On this list are some of the most famous scientists from the early days of astronomy through the modern era, and a summary of some of their achievements. Any list of famous astronomers has to include a varied collection of great scientists from the Greeks to the modern era, big thinkers who tackled many fields as well as modern astronomers who made significant discoveries and helped popularize astronomy. Credit: Karl Tate, SPACE.com The Ptolemaic geocentric model of the universe, devised by the Greek scientist Claudius Ptolemy, had everything revolving around Earth. Credit: Bartolomeu Velho, Public Domain When most people believed the world was flat, the notable Greek mathematician, astronomer and geographer Eratosthenes (276 BCE- 195 BCE) used the sun to measure the size of the round Earth. His measurement of 24,660 miles (39,690 kilometers) was only 211 miles (340 km) off the true measurement.

The ancient Greek astronomer and mathematician Claudius Ptolemy (AD 90- 168) set up a model of the solar system in which the sun, stars, and other planets revolved around Earth. Known as the Ptolemaic system, it remained in place for hundreds of years, though it turned out to be flat wrong. Persian astronomer Abd al-Rahman al-Sufi (903-986), known as Azophi to Westerners, made the first known observation of a group of stars outside of the Milky Way, the Andromeda galaxy. Nicolaus Copernicus Credit: Public Domain In 16th century Poland, astronomer Nicolaus Copernicus (1473-1543) proposed a model of the solar system that involved the Earth revolving around the sun. The model wasn't completely correct, as astronomers of the time struggled with the backwards path Mars sometimes took, but it eventually changed the way many scientists viewed the solar system.

Using detailed measurements of the path of planets kept by Danish astronomer Tycho Brahe , Johannes Kepler (1571-1630) determined that planets traveled around the sun not in circles but in ellipses. In so doing, he calculated three laws involving the motions of planets that astronomers still use in calculations today. Galileo Galilei is credited with discovering the first four moons of Jupiter. Credit: NASA Born in Italy, Galileo Galilei (1564-1642) is often credited with the creation of the optical telescope, though in truth he improved on existing models. The astronomer (also mathematician, physicist and philosopher) turned the new observational tool toward the heavens, where he discovered the four primary moons of Jupiter (now known as the Galilean moons), as well as the rings of Saturn. Though a model of the Earth circling the sun was first proposed by Copernicus, it took some time before it became widely accepted. Galileo is most widely known for defending the idea several years after Kepler had already calculated the path of planets, and Galileo wound up under house arrest at the end of his lifetime because of it.

Dutch scientist Christiaan Huygens (1629-1695) proposed the earliest theory about the nature of light, a phenomena that puzzled scientists for hundreds of years. His improvements on the telescope allowed him to make the first observations of Saturn's rings and to discover its moon, Titan. Building on the work of those who had gone before him, English astronomer Sir Isaac Newton (1643-1727) is most famous for his work on forces, specifically gravity. He calculated three laws describing the motion of forces between objects, known today as Newton's laws. Famed physicist Albert Einstein at the blackboard. Credit: NASA In the early 20th century, German physicist Albert Einstein (1879-1955) became of of the most famous scientists ever after proposing a new way of looking at the universe that went beyond current understanding. Einstein suggested that the laws of physics are the same throughout the universe, that the speed of light in a vacuum is constant, and that space and time are linked in an entity known as space-time, which is distorted by gravity.

At the same time Einstein was expanding man's view of the universe, American astronomer Edwin Hubble (1899-1953) calculated that a small blob in the sky existed outside of the Milky Way. Prior to his observations, the discussion over the size of the universe was divided as to whether or not only a single galaxy existed. Hubble went on to determine that the universe itself was expanding, a calculation which later came to be known as Hubble's law. Hubble's observations of the various galaxies allowed him to create a standard system of classification still used today. American astronomer Carl Sagan (1934-1996) may not have been a great scientists in comparison to some on this list, but he is one of the most famous astronomers. Sagan not only made important scientific studies in the fields of planetary science, he also managed to popularized astronomy more than any other individual. His charismatic teaching and boundless energy impacted people around the world as he broke down complicated subjects in a way that interested television viewers even as he educated them. Professor Stephen Hawking speaks about "Why We Should Go into Space" for the NASA Lecture Series, April 21, 2008.

Credit: NASA/Paul Alers Stephen Hawking (born 1942) has made many significant insights into the field of cosmology. He proposed that, as the universe has a beginning, it will likely also end. He also suggested that it has no boundary or border. Despite being viewed as one of the most brilliant minds since Einstein, many of Hawking's books and lectures are steered toward the general public as he seeks to educate people about the universe they live in. Other astronomers that achieved significant discoveries and are often mentioned among the greats: Italian astronomer Giovanni Cassini (1625-1712) measured how long it took the planets Jupiter and Mars to rotate, as well as discovering four moons of Saturn and the gap in the planet's rings. When NASA launched a satellite to orbit Saturn and its moons in 1997, it was fittingly dubbed Cassini.

Edmond Halley (1656-1742) was the British scientist who reviewed historical comet sightings and proposed that the comet which appeared in 1456, 1531, 1607, and 1682 were all the same, and would return in 1758. Although he died before its return, he was proven correct, and the comet was named in his honor. French astronomer Charles Messier (1730-1817) composed a database of objects known at the time as "nebulae," which included 103 objects at its final publication, though additional objects were added based on his personal notes. Many of these objects are often listed with their catalog name, such as the Andromeda Galaxy, known as M31. Messier also discovered 13 comets over the course of his lifetime. British astronomer William Herschel (1738-1822) cataloged over 2,500 deep sky objects. He also discovered Uranus and its two brightest moons, two of Saturn's moons, and the Martian ice caps.

William trained his sister, Caroline Herschel (1750-1848), in astronomy, and she became the first woman to discover a comet, identifying several over the course of her lifetime. Henrietta Swann Leavitt (1868-1921) was one of several women working as a human "computer" at Harvard college, identifying images of variable stars on photographic plates. She discovered that the brightness of a special flashing star known as a Cepheid variable was related to how often it pulsed. This relationship allowed astronomers to calculate the distances of stars and galaxies, the size of the Milky Way, and the expansion of the universe. [This entry was corrected June 12, 2012.] American astronomer Harlow Shapley (1885-1972) calculated the size of the Milky Way galaxy and general location of its center. He argued that the objects known as "nebula" lay within the galaxy, rather than outside of it, and in 1920 participated in the "Great Debate". He also incorrectly disagreed with Edwin Hubble's observations that the universe boasted galaxies other than the Milky Way.

Frank Drake with a young observer at the Lick Observatory. Credit: SETI Institute Frank Drake (born 1930) is one of the pioneers in the search for extraterrestrial intelligence. He was one of the founders of the Search for Extraterrestrial Intelligence ( SETI ) and the deviser of the Drake equation, a mathematical equation used to estimate the number of extraterrestrial civilizations in the Milky Way galaxy able to be detected. American astronomer William K. Hartmann (born 1939) put forth the most widely accepted theory on the formation of the moon in 1975. He proposed that, after a collision with a large body scooped, debris from the Earth coalesced into the moon. —Nola Taylor Redd Are Our Textbooks Wrong? Astronomers Clash Over Hubble's Legacy - Universe Today Universe Today Are Our Textbooks Wrong? Astronomers Clash Over Hubble’s Legacy Article Updated: 23 Dec , 2015 by Dan Majaess “No scientific discovery is named after its discoverer,” – Stigler/Merton.

Edwin Hubble’s contributions to astronomy earned him the honor of having his name bestowed upon arguably the most famous space telescope ( the Hubble Space Telescope , HST). Contributions that are often attributed to him include the discovery of the extragalactic scale (there exist countless other galaxies beyond the Milky Way ), the expanding Universe (the Hubble constant), and a galaxy classification system ( the Hubble Tuning Fork ). However, certain astronomers are questioning Hubble’s pre-eminence in those topics, and if all the credit is warranted. “[The above mentioned] discoveries … are well-known … and most astronomers would associate them solely with Edwin Hubble; yet this is a gross oversimplification. Astronomers and historians are beginning to revise that standard story and bring a more nuanced version to the public’s attention,” said NASA scientist Michael J. Way, who just published a new study entitled “ Dismantling Hubble’s Legacy? ” Has history clouded our view of Hubble the man? Or are his contributions seminal to where we are today in astronomy?

Assigning credit for a discovery is not always straightforward, and Way 2013 notes, “How credit is awarded for a discovery is often a complex issue and should not be oversimplified – yet this happens time and again. Another well-known example in this field is the discovery of the Cosmic Microwave Background.” Indeed, controversy surrounds the discovery of the Universe’s accelerated expansion , which merely occurred in the late 1990s . Conversely, the discoveries attributed to Hubble transpired during the ~1920s. The Hubble Space Telescope (image credit: NASA, tweaked by D. Majaess). Prior to commencing this discussion, it’s emphasized that Hubble cannot defend his contribution since he died long ago (1889-1953). Moreover, we can certainly highlight the efforts of other individuals whose seminal contributions were overlooked without mitigating Hubble’s pertinence. The first topic discussed here is the discovery of the extragalactic scale. Prior to the 1920s it was unclear whether the Milky Way galaxy and the Universe were synonymous. In other words, was the Milky Way merely one among countless other galaxies? Astronomers H. Shapley and H.

Curtis argued the topic in the famed Island Universe debate (1920). Curtis believed in the extragalactic Universe, whereas Shapley took the opposing view (see also Trimble 1995 for a review). In the present author’s opinion, Hubble’s contributions helped end that debate a few years later and changed the course of astronomy, namely since he provided evidence of an extragalactic Universe using a distance indicator that was acknowledged as being reliable. Hubble used stars called Cepheid variables to help ascertain that M31 and NGC 6822 were more distant than the estimated size of the Milky Way, which in concert with their deduced size, implied they were galaxies. Incidentally, Hubble’s distances, and those of others, were not as reliable as believed (e.g., Fernie 1969 , Peacock 2013 ). Peacock 2013 provides an interesting comparison between distance estimates cited by Hubble and Lundmark with present values, which reveals that both authors published distances that were flawed in some manner. Having said that, present-day estimates are themselves debated.

Hubble’s evidence helped convince even certain staunch opponents of the extragalactic interpretation such as Shapley, who upon receiving news from Hubble concerning his new findings remarked (1924), “Here is the letter that has destroyed my universe.” Way 2013 likewise notes that, “The issue [concerning the extragalactic scale] was effectively settled by two papers from Hubble in 1925 in which he derived distances from Cepheid variables found in M31 and M33 (Hubble 1925a) of 930,000 light years and in NGC 6822 (Hubble 1925c) of 700,000 light years.” Hubble 1925 used Cepheids to establish the distance to M31, shown above (image credit: Noel Carboni and Greg Parker ). However, as table 1 from Way 2013 indicates (shown below), there were numerous astronomers who published distances that implied there were galaxies beyond the Milky Way.

Astronomer Ian Steer , who helps maintain the NASA/IPAC Extragalactic Database of Redshift-Independent Distances (NED-D) , has also compiled a list of 290 distances to galaxies published before 1930 . Way 2013 added that, “Many important contributions to this story have been forgotten and most textbooks in astronomy today, if they discuss the “Island Universe” confirmation at all, bestow 100% of the credit on Hubble with scant attention to the earlier observations that clearly supported his measurements.” Thus Hubble did not discover the extragalactic scale, but his work helped convince a broad array of astronomers of the Universe’s enormity. However, by comparison to present-day estimates, Hubble’s distances are too short owing partly to the existing Cepheid calibration he utilized ( Fernie 1969 , Peacock 2013 also notes that Hubble’s distances were flawed for other reasons). That offset permeated into certain determinations of the expansion rate of the Universe (the Hubble constant), making the estimate nearly an order of magnitude too large, and the implied age for the Universe too small.

Way 2013 notes, “Table 1 lists all of the main distance estimates to spiral nebulae (known to this author) from the late 1800s until 1930 when standard candles began to be found in spiral nebulae [galaxies].” (image credit: Way 2013/arXiv ). Hubble’s accreditation as the discoverer of the expanding Universe (the Hubble constant) has generated considerable discussion, which is ultimately tied to the discovery of a relationship between a galaxy’s velocity and its distance. An accusation even surfaced that Hubble may have censored the publication of another scientist to retain his pre-eminence. That accusation has since been refuted , but provides the reader an indication of the tone of the debate (see Livio 2012 ( Nature ), and references therein). Hubble published his findings on the velocity-distance relation in 1929 , under the unambiguous title, “A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae”.

Hubble 1929 states at the outset that other investigations have sought, “a correlation between apparent radial velocities and distances, but so far the results have not been convincing.” The key word being convincing, clearly a subjective term, but which Hubble believes is the principal impetus behind his new effort. In Lundmark 1924 , where a velocity versus distance diagram is plotted for galaxies (see below), that author remarks that, “Plotting the radial velocities against these relative distances, we find that there may be a relation between the two quantities, although not a very definite one.” However, Hubble 1929 also makes reference to a study by Lundmark 1925 , where Lundmark underscores that, “A rather definite correlation is shown between apparent dimensions and radial velocity, in the sense that the smaller and presumably more distant spirals have the higher space velocity.” Hubble 1929 provides a velocity-distance diagram (featured below) and also notes that, “the data indicate a linear correlation between distances and velocities”.

However, Hubble 1929 explicitly cautioned that, “New data to be expected in the near future may modify the significance of the present investigation, or, if confirmatory, will lead to a solution having many times the weight. For this reason it is thought premature to discuss in detail the obvious consequences of the present results … the linear relation found in the present discussion is a first approximation representing a restricted range in distance.” Hubble implied that additional effort was required to acquire observational data and place the relation on firm (convincing) footing, which would appear in Hubble and Humason 1931 . Perhaps that may partly explain, in concert with the natural tendency of most humans to desire recognition and fame, why Hubble subsequently tried to retain credit for the establishment of the velocity-distance relation. Hubble 1929 conveyed that he was aware of prior (but unconvincing to him) investigations on the topic of the velocity-distance relation.

That is further confirmed by van den Bergh 2011 , who cites the following pertinent quote recounted by Hubble’s assistant (Humason) for an oral history project, “The velocity-distance relationship started after one of the IAU meetings, I think it was in Holland [1928]. And Dr. Hubble came home rather excited about the fact that two or three scientists over there, astronomers, had suggested that the fainter the nebulae were, the more distant they were and the larger the red shifts would be. And he talked to me and asked if I would try and check that out.” The velocities of galaxies plotted as a function of their distance, from Lundmark 1924 (left) and Hubble 1929 (right). Note the separate scales on the x-axis. Peacock 2013 demonstrates that distances cited by both authors were ultimately flawed, and problems (albeit less acute) likewise exist with modern distances (image credit: Lundmark/MNRAS/Hubble/PNAS, assembled by D. Majaess).

Hubble 1929 elaborated that, “The outstanding feature, however, is the possibility that the velocity-distance relation may represent the de Sitter effect, and hence that numerical data may be introduced into discussions of the general curvature of space.” de Sitter had proposed a model for the Universe whereby light is redshifted as it travels further from the emitting source. Hubble suspected that perhaps his findings may represent the de Sitter effect, however, Way 2013 notes that, “Thus far historians have unearthed no evidence that Hubble was searching for the clues to an expanding universe when he published his 1929 paper (Hubble 1929b).” Indeed, nearly two decades after the 1929 publication, Hubble 1947 remarks that better data may indicate that, “redshifts may not be due to an expanding universe, and much of the current speculation on the structure of the universe may require re-examination.” It is thus somewhat of a paradox that, in tandem with the other reasons outlined, Hubble is credited with discovering that the Universe is expanding. The term redshift stems from the fact that when astronomers (e.g., V.

Slipher ) examined the spectra of certain galaxies, they noticed that although a particular spectral line should have appeared in the blue region of the spectrum (as measured in a laboratory): the line was actually shifted redward. Hubble 1947 explained that, “light-waves from distant nebulae [galaxies] seem to grow longer in proportion to the distance they have travelled It is as though the stations on your radio dial were all shifted toward the longer wavelengths in proportion to the distances of the stations. In the nebular [galaxy] spectra the stations (or lines) are shifted toward the red, and these redshifts vary directly with distance–an approximately linear relation. This interpretation lends itself directly to theories of an expanding universe. The interpretation is not universally accepted, but even the most cautious of us admit that redshifts are evidence either of an expanding universe or of some hitherto unknown principle of nature.” Top, spectra for galaxies that are redshifted (image credit: JPL/Caltech/Planck ).

As noted above, Hubble was not the first to deduce a velocity-distance relation for galaxies, and Way 2013 notes that, “Lundmark (1924b): first distance vs. velocity plot for spiral nebulae [galaxies] …Georges Lemaitre (1927): derived a non–static solution to Einstein’s equations and coupled it to observations to reveal a linear distance vs. redshift relation with a slope of 670 or 575 km/s/Mpc (depending on how the data is grouped) …” Although Hubble was aware of Lundmark’s research, he and numerous other astronomers were likely unaware of the now famous 1927 Lemaitre study, which was published in an obscure journal (see Livio 2012 ( Nature ), and discussion therein). Steer 2013 notes that, “Lundmark’s [1924] distance estimates were consistent with a Hubble constant of 75 km/s/Mpc [which is close to recent estimates].” (see also the interpretation of Peacock 2013 ).

Certain distances established by Lundmark appear close to present determinations (e.g., M31, see the table above). So why was Hubble credited with discovering the expanding Universe? Way 2013 suggests that, “Hubble’s success in gaining credit for his … linear distance-velocity relation may be related to his verification of the Island Universe hypothesis –after the latter, his prominence as a major player in astronomy was affirmed. As pointed out by Merton (1968) credit for simultaneous (or nearly so) discoveries is usually given to eminent scientists over lesser-known ones.” Steer told Universe Today that, “Lundmark in his own words did not find a definite relation between redshift and distance, and there is no linear relation overplotted in his redshift-distance graph.

Where Lundmark used a single unproven distance indicator (galaxy diameters), cross-checked by a single unproven distance to the Andromeda galaxy, Hubble used multiple indicators including one still in use (brightest stars), cross-checked with distances to multiple galaxies based on Cepheids variables stars.” Concerning assigning credit for the discovery of the expansion of the Universe, Way 2013 concludes that, “Overall we find that Lemaitre was the first to seek and find a linear relation between distance and velocity in the context of an expanding universe, but that a number of other actors (e.g. Carl Wirtz, Ludwik Silberstein, Knut Lundmark, Edwin Hubble, Willem de Sitter) were looking for a relation that fit into the context of de Sitter’s [Universe] Model B world with its spurious radial velocities [the redshift].” A partial list of the various contributors highlighted by van den Bergh 2011 is provided below. “The history of the discovery of the expansion of the Universe may be summarized [above],” van den Bergh 2011 (image credit: van den Bergh/JRASC/arXiv ).

Way and Nussbaumer 2011 assert that, “It is still widely held that in 1929 Edwin Hubble discovered the expanding Universe … that is incorrect. There is little excuse for this, since there exists sufficient well-supported evidence about the circumstances of the discovery.” In sum, the author’s personal opinion is that Hubble’s contributions to astronomy were seminal. Hubble helped convince astronomers of the extragalactic distance scale and that a relationship existed between the distance to a galaxy and its velocity, thus propelling the field and science forward. His extragalactic distances, albeit flawed, were also used to draw important conclusions (e.g., by Lemaitre 1927). However, it is likewise clear that other individuals are meritorious and deserve significant praise. The contributions of those scientists should be highlighted in parallel to Hubble’s research, and astronomy textbooks should be revised to emphasize those achievements A fuller account should be cited of the admirable achievements made by numerous astronomers working in synergy during the 1920s.

There are a diverse set of opinions on the topics discussed, and the reader should remain skeptical (of the present article and other interpretations), particularly since knowledge of the topic is evolving and more is yet to emerge. Two talks from the “ Origins of the Expanding Universe: 1912-1932 ” conference are posted below (by H. Nussbaumer and M. Way), in addition to a talk by I. Steer from a separate event. Was the real discovery of the expanding universe lost in translation? Was the real discovery of the expanding universe lost in translation? November 9, 2011 This illustration shows American astronomer Edwin Hubble (1889-1953) on the right and Belgian priest and cosmologist Georges Lemaître (1894-1966) on the left. Based on new evidence, both scientists should share credit for independently uncovering evidence for the expanding universe in the late 1920s. Lemaître is also credited with proposing a theory for the origin of the universe that would later be called the "big bang." The telescope on the left is the 100-inch Hooker Telescope on Mt. Wilson in California.

The Hubble Space Telescope is on the right. Credit: NASA, ESA, and A. Feild (STScI) (PhysOrg.com) -- The greatest astronomical discovery of the 20th century may have been credited to the wrong person. But it turns out to have been nobody's fault except for that of the actual original discoverer himself. Writing in the November 10th issue of the journal Nature, astrophysicist Mario Livio of the Space Telescope Science Institute has put to bed a growing conspiracy theory about who was fairly credited for discovering the expanding universe. For nearly a century, American astronomer Edwin P. Hubble has held the fame for this landmark discovery, which would recast all of 20th century astronomy. Hubble reported that the universe is uniformly expanding in all directions. It solved Einstein's dilemma of explaining why the universe didn't already collapse under its own gravity. Ironically, Hubble never got a Nobel Prize for this discovery, though astronomers from two teams who independently uncovered evidence for an accelerating universe won the 2011 Noble Prize in Physics. But Hubble did get the most celebrated telescope of modern history named after him.

Hubble published his landmark paper in which he determined the rate of expansion of the universe in 1929. This was based on the apparent recessional velocities (deduced from redshifts) of galaxies, as previously measured by astronomer Vesto Slipher, coupled to distances to the same galaxies, as determined by Hubble. Hubble's analysis showed that the farther the galaxy was, the faster it appeared to be receding. The rate of cosmic expansion is now known as the Hubble Constant. But two years earlier, a Belgian priest and cosmologist, Georges Lemaître, published very similar conclusions, and he calculated a rate of expansion similar to what Hubble would publish two years later. Lemaître based his analysis on Slipher's same redshift data, which he combined with estimates of galaxy distances inferred from Hubble's 1926 published observations. But Lemaître's discovery went unnoticed because it was published in French, in a rather obscure Belgian science journal called the Annales de la Société Scientifique de Bruxelles (Annals of the Brussels Scientific Society). The story would have ended there, except that Lemaître's work was later translated and published in the Monthly Notices of the Royal Astronomical Society.

When published in 1931, some of Lemaître's own calculations from 1927, of what would be later called the Hubble Constant, were omitted! The fact that paragraphs were missing from the translated paper has been known (although not widely) since 1984. There has been persistent speculation among astronomers over "who dunnit?" Did the Monthly Notices editors cut the paragraphs out? Did Edwin Hubble himself have an influencing hand and censor the paper to eliminate any doubt that he was the original discoverer of the expanding universe? After going through hundreds of pieces of correspondence of the Royal Astronomical Society, as well as minutes of the RAS meetings, and material from the Lemaître Archive, Livio has discovered that Lemaître omitted the passages himself when he translated the paper into English!

In one of two "smoking-gun letters" uncovered by Livio, Lemaître wrote to the editors: "I did not find advisable to reprint the provisional discussion of radial velocities which is clearly of no actual interest, and also the geometrical note, which could be replaced by a small bibliography of ancient and new papers on the subject." The remaining question is why Lemaître essentially erased evidence for credit due to him, for first discovering (at least tentatively) the expanding universe. Livio concludes, "Lemaître's letter also provides an interesting insight into the scientific psychology of some of the scientists of the 1920s. Lemaître was not at all obsessed with establishing priority for his original discovery. Given that Hubble's results had already been published in 1929, he saw no point in repeating his more tentative earlier findings again in 1931." Perhaps in some alternative history parallel universe, people are marveling at the deep-space pictures from the Lemaître Space Telescope. Hubble Space Telescope - News News Was the Real Discovery of the Expanding Universe Lost in Translation? Release date: Nov 9, 2011 1:00 PM (EST) Writing in the Nov.

10 issue of the journal Nature, Space Telescope Science Institute astrophysicist Mario Livio solves the mystery of why paragraphs disappeared during the 1931 translation of Belgian cosmologist Georges Lemaître's remarkable 1927 paper showing that the universe is expanding. For nearly a century, American astronomer Edwin Hubble has held the fame for this landmark discovery, which would recast all of 20th century astronomy. After going through hundreds of pieces of correspondence of the Royal Astronomical Society, as well as minutes of the RAS meetings, and material from the Lemaître Archive, Livio has discovered that Lemaître omitted the passages himself when he translated the paper into English! This illustration shows Edwin Hubble (1889-1953) on the right and Georges Lemaître (1894-1966) on the left. The telescope on the left is the 100-inch Hooker Telescope on Mt. Wilson in California. The Hubble Space Telescope is on the right. Release ID: STScI-2011-36 Illustration Credit: NASA , ESA , and A.

Feild ( STScI ) The Full Story Release date: Nov 9, 2011 News Release number: STScI-2011-36 News Release number: STScI-2011-36 The greatest astronomical discovery of the 20th century may have been credited to the wrong person. But it turns out to have been nobody's fault except for that of the actual original discoverer himself. Writing in the November 10th issue of the journal Nature, astrophysicist Mario Livio of the Space Telescope Science Institute has put to bed a growing conspiracy theory about who was fairly credited for discovering the expanding universe. For nearly a century, American astronomer Edwin P. Hubble has held the fame for this landmark discovery, which would recast all of 20th century astronomy. Hubble reported that the universe is uniformly expanding in all directions. It solved Einstein's dilemma of explaining why the universe didn't already collapse under its own gravity. Ironically, Hubble never got a Nobel Prize for this discovery, though astronomers from two teams who independently uncovered evidence for an accelerating universe won the 2011 Noble Prize in Physics.

But Hubble did get the most celebrated telescope of modern history named after him. Hubble published his landmark paper in which he determined the rate of expansion of the universe in 1929. This was based on the apparent recessional velocities (deduced from redshifts) of galaxies, as previously measured by astronomer Vesto Slipher, coupled to distances to the same galaxies, as determined by Hubble. Hubble's analysis showed that the farther the galaxy was, the faster it appeared to be receding. The rate of cosmic expansion is now known as the Hubble Constant. But two years earlier, a Belgian priest and cosmologist, Georges Lemaître, published very similar conclusions, and he calculated a rate of expansion similar to what Hubble would publish two years later. Lemaître based his analysis on Slipher's same redshift data, which he combined with estimates of galaxy distances inferred from Hubble's 1926 published observations. But Lemaître's discovery went unnoticed because it was published in French, in a rather obscure Belgian science journal called the Annales de la Société Scientifique de Bruxelles (Annals of the Brussels Scientific Society).

The story would have ended there, except that Lemaître's work was later translated and published in the Monthly Notices of the Royal Astronomical Society. When published in 1931, some of Lemaître's own calculations from 1927, of what would be later called the Hubble Constant, were omitted! The fact that paragraphs were missing from the translated paper has been known (although not widely) since 1984. There has been persistent speculation among astronomers over "who dunnit?" Did the Monthly Notices editors cut the paragraphs out? Did Edwin Hubble himself have an influencing hand and censor the paper to eliminate any doubt that he was the original discoverer of the expanding universe? After going through hundreds of pieces of correspondence of the Royal Astronomical Society, as well as minutes of the RAS meetings, and material from the Lemaître Archive, Livio has discovered that Lemaître omitted the passages himself when he translated the paper into English!

In one of two "smoking-gun letters" uncovered by Livio, Lemaître wrote to the editors: "I did not find advisable to reprint the provisional discussion of radial velocities which is clearly of no actual interest, and also the geometrical note, which could be replaced by a small bibliography of ancient and new papers on the subject." The remaining question is why Lemaître essentially erased evidence for credit due to him, for first discovering (at least tentatively) the expanding universe. Livio concludes, "Lemaître's letter also provides an interesting insight into the scientific psychology of some of the scientists of the 1920s. Lemaître was not at all obsessed with establishing priority for his original discovery. Given that Hubble's results had already been published in 1929, he saw no point in repeating his more tentative earlier findings again in 1931." Perhaps in some alternative history parallel universe, people are marveling at the deep-space pictures from the Lemaître Space Telescope. Contact Astronomy - The Origins of the Universe The Origins of the Universe By observing galaxies formed billions of years ago, astronomers have been able to paint an increasingly detailed picture of how the universe evolved.

According to the widely accepted Big Bang theory, our universe was born in an explosive moment approximately fifteen billion years ago. All of the universe's matter and energy-even the fabric of space itself-was compressed into an infinitesimally small volume and then began expanding at an incredible rate. Within minutes, the universe had grown to the size of the solar system and cooled enough so that equal numbers of protons, neutrons, and the simplest atomic nuclei had formed. After several hundred thousand years of expansion and cooling, neutral atoms-atoms with equal numbers of protons and electrons-were able to form and separate out as distinct entities. Still later, immense gas clouds coalesced to form primitive galaxies, and, from them, stars. Our own solar system formed relatively recently-about five billion years ago-when the universe was two-thirds its present size. In April 2000, an international team of cosmologists supported in part by NSF released the first detailed images of the universe in its infancy. The images reveal the structure that existed in the universe when it was a tiny fraction of its current age and one thousand times smaller and hotter than today.

The project, dubbed BOOMERANG (Balloon Observations of Millimetric Extragalactic Radiation and Geophysics) captured the images using an extremely sensitive telescope suspended from a balloon that circumnavigated the Antarctic in late 1998. The BOOMERANG images were the first to bring into sharp focus the faint glow of microwave radiation, called the cosmic microwave background, that filled the embryonic universe soon after the Big Bang. Analysis of the images already has shed light on the nature of matter and energy, and indicates that space is "flat." The roots of the Big Bang theory reach back to 1929, the year Edwin Hubble and his assistant Milton Humason discovered that the universe is expanding. Between 1912 and 1928, astronomer Vesto Slipher used a technique called photographic spectroscopy-the measurement of light spread out into bands by using prisms or diffraction gratings-to examine a number of diffuse, fuzzy patches. Eventually, Hubble used these measurements, referred to as spectra, to show that the patches were actually separate galaxies.

Slipher, who did his work at Lowell Observatory in Flagstaff, Arizona, found that in the vast majority of his measurements the spectral lines appeared at longer, or redder, wavelengths. From this he inferred that the galaxies exhibiting such "red shifts" were moving away from Earth, a conclusion he based on the Doppler effect. This effect, discovered by Austrian mathematician and physicist Christian Doppler in 1842, arises from the relative motion between a source and an observer. This relative motion affects wavelengths and frequencies. Shifts in frequency are what make ambulance sirens and train whistles sound higher-pitched as they approach and lower-pitched as they move away. Hubble took these findings and eventually determined the distances to many of Slipher's galaxies. What he found was amazing: The galaxies were definitely moving away from Earth, but, the more distant the galaxy, the faster it retreated. Furthermore, Hubble and Humason discovered that the ratio of a galaxy's speed (as inferred from the amount of red shift) to its distance seemed to be about the same for all of the galaxies they observed.

Because velocity appeared proportional to distance, Hubble reasoned, all that remained was to calculate that ratiothe ratio now referred to as the Hubble Constant. And what is the value of the Hubble Constant? After 70 years of increasingly precise measurements of extragalactic velocities and distances, astronomers are at last closing in on this elusive number. Wendy Freedman is one of the scientists working to define the Hubble Constant. As head of an international team at the Carnegie Observatories in Pasadena, California, Freedman surveys the heavens using the Hubble Space Telescope to measure distances to other galaxies. With grants from NSF, she is building on the legacy of Henrietta Leavitt, who discovered in the early 1900s that the absolute brightness of Cepheid variable stars is related to the time it takes the stars to pulsate (its period). Scientists can measure the period of a Cepheid in a distant galaxy and measure its apparent brightness. Since they know the period, they know what the absolute brightness should be. The distance from Earth to the Cepheid variable star is inferred from the difference between absolute and apparent brightness. Freedman and her colleagues are using this method to determine distances to other galaxies.

With these Cepheid distances, Freedman's group calibrates other distance-determination methods to reach even more far-flung galaxies. This information, in turn, enables them to estimate the Hubble Constant. Researchers closing in on a definitive value for the Hubble Constant are doing so in the midst of other exciting developments within astronomy. In 1998, two independent teams of astronomers, both with NSF support, concluded that the expansion of the universe is accelerating. Their unexpected findings electrified the scientific community with the suggestion that some unknown force was driving the universe to expand at an ever increasing rate. Earlier evidence has supported the possibility that the gravitational attraction among galaxies would eventually slow the universe's growth. In its annual survey of the news, Science magazine named the accelerating universe as the science discovery of the year in 1998. Jeremy Mould, director of Mount Stromlo and Siding Spring Observatories in Canberra, Australia, has studied another aspect of the expansion of the universe. Scientists generally assume that everything in the universe is moving uniformly away from everything else at a rate given by the Hubble constant. Mould is interested in departures from this uniform Hubble flow. These motions are known as peculiar velocities of galaxies.

Starting in 1992, Mould and his colleague John Huchra of the Harvard Smithsonian Center for Astrophysics used an NSF grant to study peculiar velocities of galaxies by creating a model of the universe and its velocity that had, among other things, galaxy clusters. These galaxies in clusters were accelerated by the gravitational field of all the galaxies in the locality. All other things being equal, a high-density universe produces large changes in velocity. This means that measurements of peculiar velocities of galaxies can be used to map the distribution of matter in the universe. Mould and Huchra's model has seeded major efforts to collect measurements of the actual density of the universe so as to map its mass distribution directly. In the modular universewhere stars are organized into galaxies, galaxies into clusters, clusters into superclustersstudies of galaxies, such as those conducted by Mould, give us clues to the organization of larger structures. To appreciate Mould's contribution to our understanding of these organizing principles, consider that a rich galaxy cluster can contain thousands of galaxies, and each galaxy can contain tens of billions to hundreds of billions of stars. Astronomers now estimate that there are tens of billions of galaxies in the observable universe.

Large, diffuse groupings of galaxies emerging from the empty grandeur of the universe show us how the universe is put together-and perhaps even how it all came to be. Only one of those extragalactic islands of starsthe Andromeda Galaxyis faintly visible to the naked eye from the northern hemisphere, while two small satellite galaxies of the Milky Waythe Large and Small Magellanic Cloudscan be seen from Earth's southern hemisphere. Telescopes augmented with various technologies have enabled astronomersnotably NSF grantee Gregory Bothun of the University of Oregonto discover galaxies that, because of their extreme diffuseness, went undetected until the 1980s. These "low-surface-brightness" galaxies effectively are masked by the noise of the night sky, making their detection a painstaking process. More than 1,000 of these very diffuse galaxies have been discovered in the past decade, but this is only the beginning. "Remarkably, these galaxies may be as numerous as all other galaxies combined," says Bothun.

"In other words, up to 50 percent of the general galaxy population of the universe has been missed, and this has important implications with respect to where matter is located in the universe." What does it mean when they say the universe is expanding?(Everyday Mysteries: Fun Science Facts from the Library of Congress) What does it mean when they say the universe is expanding? When scientists talk about the expanding universe, they mean that it has been growing ever since its beginning with the Big Bang. The galaxies outside of our own are moving away from us, and the ones that are farthest away are moving the fastest. This means that no matter what galaxy you happen to be in, all the other galaxies are moving away from you. However, the galaxies are not moving through space, they are moving in space, because space is also moving. In other words, the universe has no center; everything is moving away from everything else. If you imagine a grid of space with a galaxy every million light years or so, after enough time passes this grid will stretch out so that the galaxies are spread to every two million light years, and so on, possibly into infinity.

The universe encompasses everything in existence, from the smallest atom to the largest galaxy; since forming some 13.7 billion years ago in the Big Bang, it has been expanding and may be infinite in its scope. The part of the universe of which we have knowledge is called the observable universe, the region around Earth from which light has had time to reach us. One famous analogy to explain the expanding universe is imagining the universe like a loaf of raisin bread dough. As the bread rises and expands, the raisins move farther away from each other, but they are still stuck in the dough. In the case of the universe, there may be raisins out there that we can’t see any more because they have moved away so fast that their light has never reached Earth. Fortunately, gravity is in control of things at the local level and keeps our raisins together. Who Figured This Out? The American astronomer Edwin Hubble made the observations in 1925 and was the first to prove that the universe is expanding. He proved that there is a direct relationship between the speeds of distant galaxies and their distances from Earth. This is now known as Hubble’s Law.

The Hubble Space Telescope was named after him, and the single number that describes the rate of the cosmic expansion, relating the apparent recession velocities of external galaxies to their distance, is called the Hubble Constant. So, is the Universe Infinite? It might be easier to explain about the beginning of the universe and the Big Bang Theory, than to talk about how it will end. It is possible that the universe will last forever, or it may be crushed out of existence in a reverse of the Big Bang scenario, but that would be so far in the future that it might as well be infinite. Until recently, cosmologists (the scientists who study the universe) assumed that the rate of the universe’s expansion was slowing because of the effects of gravity. However, current research indicates that the universe may expand to eternity. But research continues and new studies of supernovae in remote galaxies and a force called dark energy may modify the possible fates of the universe.

Related Web Sites HubbleSite - The Telescope - Hubble Essentials - About Edwin Hubble About Edwin Hubble Hubble Essentials: About Edwin Hubble The Legacy of Edwin Hubble The Hubble Space Telescope was named after astronomer Edwin Powell Hubble (1889–1953), who made some of the most important discoveries in modern astronomy. As an astronomer, Dr. Hubble was a late bloomer. Before discovering his passion for the stars, Dr. Hubble earned a law degree and served in World War I. However, after practicing law for one year, he decided to “chuck law for astronomy,” knowing that “even if [he] were second rate or third rate, it was astronomy that mattered.” In the 1920s, while working at the Mt. Wilson Observatory with the most advanced technology of the time, Dr. Hubble showed that some of the numerous distant, faint clouds of light in the universe were actually entire galaxies—much like our own Milky Way. The realization that the Milky Way is only one of many galaxies forever changed the way astronomers viewed our place in the universe. But perhaps his greatest discovery came in 1929, when Dr.

Hubble determined that the farther a galaxy is from Earth, the faster it appears to move away. This notion of an "expanding" universe formed the basis of the Big Bang theory, which states that the universe began with an intense burst of energy at a single moment in time  and has been expanding ever since.

Question: Which astronomer is credited with discovering that the Universe is expanding?
Answer: EDWIN HUBBLE