astronomy and cosmology: big bang theory and modern …astronomy and cosmology: big bang theory and...

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Astronomy and Cosmology: Big Bang Theory and Modern

Cosmology

Introduction ■

Cosmologists, who are scientists who study the na-ture and history of the universe as a whole, state that the universe began in a state of infi nite or near-infi nite density about 13.7 billion years ago and has been ex-panding and cooling ever since. The rapid beginning of this expansion is termed the big bang. Although many questions about the big bang remain, and alternative explanations of the universe’s history have been pro-posed, most cosmologists agree that the big bang the-ory is strongly supported by many observations. These include the movements of distant galaxies and the na-ture of the cosmic microwave background, a sky-fi lling bath of radio waves that can be explained as the after-glow of the big bang. The big bang began the process of synthesizing (putting together) the nuclei of all the elements of which Earth and we ourselves are made. It is the organizing or central concept of most modern cosmology.

Historical Background and ■

Scientifi c Foundations Astronomers observed in the 1910s that the spiral neb-ulae are receding from us. Spiral nebulae are actually galaxies—vast wheeling clouds of stars, dust, and gas—but this was not known at the time, because the spiral nebulae were visible only as pinwheel-shaped smears of light in even the best telescopes. The recession of the spiral nebulae is seen not because the spiral nebulae are shrinking, as a car driving into the distance appears to shrink (they are too far away for such an effect to be vis-ible except over very long periods of time), but because their light is shifted toward the red end of the spectrum. This redshifting was at fi rst interpreted as being caused by the Doppler effect, a phenomenon named after its

discoverer, Johann Christian Doppler (1803–1853). A commonly noticed form of the Doppler effect occurs when the sound of a police siren is pushed to higher fre-quencies as the vehicle approaches and then stretched to lower frequencies as it recedes. Light being emitted by a source moving away from the observer is stretched to lower frequencies (redder colors), hence “redshifted.”

The redshifting of light from distant spiral nebulae was interpreted as evidence that the galaxies are mov-ing away from us, like shards of a bomb moving away in all directions from the center of an explosion. This, in turn, hinted that all the matter and energy in the uni-verse were once together at a single point. However, all the spiral nebulae observed were found to be moving away from us, regardless of their location in the sky, and it seemed an impossible coincidence that Earth would just happen to be at the exact center of the universe.

In the early 1920s, astronomers realized that the spiral nebulae are actually distant galaxies. In 1927 Bel-gian priest Georges-Henri Lemaître (1894–1966) pro-posed that the universe originated as a primeval atom that exploded and began expanding until it assumed its present-day form, a dark void sprinkled with mat-ter. Lemaître cast his theory in the equations of general relativity, which had been proposed by German scien-tist Albert Einstein (1879–1955) in 1915. The theory of general relativity describes the shape of space and the nature of gravity.

Two years after Lemaître proposed his primeval-atom idea, further evidence supporting the expansion of the universe was produced by American astronomer Edwin Hubble (1889–1953). Hubble found that distant galaxies are not only receding, but that the farther away any galaxy is the faster it is receding.

General relativity allowed astronomers to make sense of both Lemaître’s theory and Hubble’s observa-tions without requiring Earth to be at the center of ev-erything. In general relativity’s picture of the expanding

Astronomy and Cosmology: Big Bang Theory and Modern Cosmology

12 SC I EN T I F I C T H O UG H T: I N CO N T E X T

universe, the big bang was not an explosion in space, like a bomb going off in an empty room; it was more like an explosion of space itself. Space, in general relativ-ity, can be curved and fi nite. An analogy is often drawn between the universe expanding and a spherical balloon being infl ated. In this analogy, three-dimensional space is like the surface of the balloon: fi nite in extent (there are only so many square inches of area on the balloon, only so many cubic miles of space in the universe), but unbounded (a fl ea crawling on the balloon’s surface would never fi nd an end or edge, likewise a space trav-eler in the universe). The illusion that Earth is at the center is explained as follows: Imagine that a number of fl eas are sitting on the balloon’s surface as it is in-fl ated. Each fl ea will observe that all its fellow fl eas are getting farther and farther away from it, and that the farther away a fellow fl ea is the faster it is receding (be-cause there is more expanding balloon surface between fl eas that are farther apart). Yet the fl eas are not crawling or hopping away from each other; that is, their physical velocity with respect to the surface of the balloon is zero in every case. Rather, it is the space they inhabit (the

balloon’s surface) that is expanding. As a result, each fl ea on the balloon will appear to itself to be at the cen-ter of a universal expansion. Yet no fl ea is at the center, for the balloon’s surface has no center.

Likewise, to an observer in any galaxy, all other gal-axies are seen to be receding in all directions, and the farther away another galaxy is, the faster it recedes. Yet this recession is not a physical velocity like that imparted to the pieces of an exploding bomb; it is caused by the expansion of the space between the galaxies.

Another aspect of the balloon-universe analogy is that if an expanding balloon is at a certain size right now, it must have been smaller in the past. This reason-ing can be applied to the balloon at every stage of its growth, extending all the way back to some small, initial size, a time when all the fl eas would have been crowded together in one dense mass. Likewise, the matter and energy of the universe must once have been crowded to-gether at a single point. The sudden beginning of the expansion of this mass was the big bang.

The expansion of space following a big bang ex-plains the redshifting of light from distant galaxies. This redshifting, today termed cosmological redshifting, is not, however, due to the Doppler effect as originally thought; distant galaxies are not redshifted because they are receding from us with actual, physical velocities. Rather, the light from those distant galaxies has been stretched during the many millions of years it took to reach us by the expansion of the space through which it traveled. This effect is called the cosmological redshift.

The big bang theory is not the only explanation of the universe that has been offered by astronomers. In fact, the term “big bang” was coined in 1949 in mock-ery of the big bang theory by English astronomer Fred Hoyle (1915–2001), who proposed an alternative theory called continuous creation. Hoyle suggested that hydro-gen atoms spontaneously appear in empty space every-where in the universe at a certain rate. Space expands, but the average density of matter throughout it remains

The Doppler shifting of light from spectroscopic binaries. Cengage Learning, Gale.

WORDS TO KNOW

DARK ENERGY: In 1998, astronomers discovered that the universe is not only expanding, but expanding faster all the time (accelerating). Since energy is required to accel-erate an object, it followed that some form of energy must be driving the accelerated expansion. Scientists do not know the nature of this energy and have not, as of 2008, been able to observe any source for it, and so have dubbed it “dark energy” until a better under-standing is obtained. Dark energy makes up about 74% of the material of the universe.

DARK MATTER: Unseen matter that has a gravitational effect on the motions of galaxies within clusters of galaxies.

MULTIVERSE: Some physicists and cosmologists propose that the universe we observe is only one of an infi nite number of universes, either superimposed in this space (in the case of the quantum multiverse) or, in other theories, located at distances so extreme that they cannot be observed. It is possible that both types of multiverse exist. Multiverse theories are suggested by the equations of physics, but not, so far, by observation. Direct obser-vation of multiverses will presumably never be possible, but indirect evidence for or against their existence may someday be available.

REDSHIFT: The lengthening of the frequency of light waves toward the red end of the visible light spectrum as they travel away from an observer; most commonly used to describe movement of stars away from Earth.


SC I EN T I F I C T H O UG H T: I N CO N T E X T 13

constant through infi nite time because of this univer-sal drizzle of new hydrogen atoms. Several cosmologists have defended continuous creation and other non-standard cosmologies up to the present day, but these are in a small minority.

Beside the recession of the distant galaxies, the fi rst strong observational evidence for the big bang theory was discovered by accident in 1965 when radio engi-neers working for Bell Telephone in Holmdel, New Jer-sey, found that a new microwave-receiving antenna they were building seemed to detect a weak microwave signal no matter what part of the sky they pointed it at. As soon became apparent, they had detected the radio af-terglow of the big bang, which had been predicted a few years earlier on theoretical grounds by American sci-entists George Gamow (1904–1968) and Ralph Apher (1921–2007) and which scientists at nearby Princeton University had begun building an antenna to detect in 1964. The phone-company engineers discovered the mi-crowave radiation before the Princeton scientists could make their fi rst observations.

The cosmic microwave background (CMB) radia-tion discovered in 1965 is not just any microwave sig-nal; it has a spectrum (variation of power over a range

of frequencies) that corresponds to the spectrum pre-dicted for a perfect black body (perfectly absorbing or radiating object) at 2.725 Kelvin, close to absolute zero. Black-body radiation fi lling the entire universe is exactly what was predicted on the basis of the big bang theory. The CMB is still one of the strongest pieces of evidence for the big bang.

However, it is not the only such evidence, because big bang theory also predicts other phenomena beside the CMB. In particular, it predicts that within the fi rst three minutes after the beginning of the universe, tem-peratures would have dropped low enough to permit the formation of certain atoms. Three light elements—hydrogen, helium, and lithium—would have formed under these conditions. Big bang theory predicts that about 24% of the ordinary matter in the universe should consist of helium atoms—and so it does. All elements heavier than lithium were synthesized later in the histo-ry of the universe in the hearts of stars, where the nuclei of lighter atoms can be welded together by fast colli-sions. This process is termed stellar nucleosynthesis. All the carbon, iron, oxygen, nitrogen, and other elements of which Earth and our own bodies are composed were forged by stellar nucleosynthesis.

An original diagram of the “big bang” theory promoted by young Belgian priest and scientist Georges-Henri Lemaître (1894–1966). © Bettmann/Corbis.



Stellar nucleosynthesis began inside stars 100–1,000 times the mass of our sun, which began to form about 100 million years after the big bang, fl ooding the universe with its fi rst starlight. These fi rst stars eventu-ally exploded, scattering the universe’s fi rst heavy el-ements into space as clouds of dust and gas. Some of these clouds eventually clumped again under the pull of gravity and formed second-generation stars. Many of these second-generation stars have also lived out their life cycle and exploded, synthesizing further heavy el-ements, and the debris from these explosions has col-lected into a third generation of stars. Our own sun (including its planets) is one of these third-generation systems. Confusingly, fi rst-generation stars are termed Population III, second-generation stars Population II, and third-generation stars Population I. No Population III stars exist in the nearby universe, since they existed primarily during the fi rst billion years after the big bang (13.7 billion years ago). Astronomers are striving to de-tect traces of these earliest stars in the most distant uni-verse but have not yet unambiguously succeeded.

Further confi rmation of the big bang theory has come from data collected by space probes, especially NASA’s Cosmic Background Explorer (COBE, launched in 1989) and Wilkinson Microwave Anisotropy Probe (WMAP, launched in 2001). Specifi cally, the modern big bang theory includes a feature called infl ation. Infl ation is an extremely rapid expansion supposedly undergone by the universe from 10 –35 to 10 –32 seconds after the

beginning of the big bang. Infl ation theory predicts that subatomic-scale quantum fi eld fl uctuations—subatomic in scale, but as large as the whole universe during the brief infl ationary period—would have seeded the new universe with irregularities that grew as the universe grew, eventually spanning the sky. (Similarly, small dots marked on an uninfl ated balloon become large when the balloon is infl ated.) These irregularities should appear as a pattern of slight unevenness in the CMB, and their pattern, according to the theory, should have a certain random character. The CMB is generally quite even in all directions, to about 1 part in 100,000, but it does vary slightly from place to place, and its variations have been mapped by the COBE and WMAP satellites. The random character of its blotches or brightness variations, termed its angular power spectrum, closely matches the predictions of infl ation theory.

A controversial recent development of big bang theory has been the hypothesis that there may be an infi nite number of big bangs and an infi nite number of universes, isolated from each by immense distances. Although direct physical evidence for the existence of other universes is not available, some interpretations of quantum physics—which is intimately related to the big bang—seem to call for a many-worlds reality or multi-verse. By the early 2000s, a variety of multiverse theo-ries were being debated by cosmologists, but none had yet been put to any observational test. Such tests are not impossible in principle, even though other universes can

This photo taken by the Hubble Space Telescope shows a diffuse cloud of glowing gas and dust, which is the most active region of star formation in the local universe. NASA/Getty Images.



never be directly observed: equations describing the formation of such universes might predict certain char-acteristics of our own universe, which might then be ei-ther observed or ruled out by observation. However, so far, all multiverse theories remain speculative.

A startling advance in modern cosmology occurred in 1998 as a result of observations of distant supernovae (exploding stars). This was the discovery that not only is the universe expanding, but its expansion is accelerating—getting faster. This has forced scientists to conclude that some unknown form of energy is driving the accelera-tion. The nature of this energy is still unknown as of 2008, though several possibilities have been proposed. Because it is unseen and its nature obscure, it has been dubbed “dark energy.”

In recent years most astronomers have also been convinced of the existence of a form of matter that is scattered unevenly throughout the universe but does not refl ect or absorb light, hence it is called “dark” mat-ter. The nature of the dark matter is also unknown, but by examining the CMB measurements from WMAP and other data, cosmologists have concluded that the universe consists of 4% ordinary matter (atoms, pho-tons, neutrinos), 22% dark matter (nature unknown, but exerting gravitational pull that shapes galaxies and clus-ters of galaxies), and 74% dark energy (nature completely

unknown). Matter and energy can be lumped and com-pared in this way because, as Einstein’s theory of special relativity showed in 1905, the two are interchangeable.

Modern cosmology has thus reached a peculiar state. It has confi rmed its answers to basic questions about the history of the universe yet raised for itself other questions that are at least as great. Infl ationary big bang theory has passed several observational tests with close agree-ment, and most cosmologists have strong confi dence in the theory; we therefore seem to have a good working account of the history of the universe thus far, starting with its still-mysterious origin at time zero. But starting a mere decade or so ago, cosmologists have confronted a universe that consists mostly (about 96%) of substances (dark matter, dark energy) whose nature is unknown. They also confront the possibility that the observable universe may be either all that exists, or an infi nitely tiny fraction of all that exists (one universe in an infi n-ity of universes). Also, modern cosmology is uncertain about what the ultimate future of the universe will be. Accelerating expansion rules out an eventual slow-down of the post-big bang expansion with ultimate re-collapse into an infi nitely dense point. This hints that the uni-verse will grow infi nitely old, spending eternity in an al-most perfectly dark, cold, diffuse state; however, this is not certain. Quantum fl uctuations may re-ignite a new

This image provided by NASA shows the results from the Wilkinson Microwave Anisotropy Probe (WMAP). By the faint cosmic glow of the oldest known light, physicists say they have found evidence that the universe grew to astounding proportions in less than the blink of an eye. In that trillionth of a second after the big bang, the universe expanded from the size of a marble to a volume larger than all of observable space through a process known as infl ation. AP Images/NASA.



IN CONTEXT: THE ANTHROPIC ARGUMENT

The fact that human beings exist at all becomes more puzzling the more scientists study the cosmos. If things had been just a little different, we could never have evolved. For example, if the universe had expanded too fast after the big bang, matter would have been dispersed too quickly for stars and galaxies to form, and so human beings would never have had a home world on which to evolve. Several other physical constants also have values that, if slightly different, would not have permitted life to appear.

It is not yet obvious to scientists why these constants must have their precise, life-permitting values—if they must have those values at all. Physicists often favor the view that these values are necessary, but they do not yet know why. Cosmologists, on the other hand, tend to favor what is termed the anthropic (human-centered) argument. According to the anthropic argument, there is an infi nity of universes with dif-ferent physical constants—a multiverse. On this view, all other universes besides this one are too far away to be observed. In most of these universes, according to the anthropic argument, the physical constants are wrong for the appearance of life, and there are no intelligent observers in them. We observe this universe with its lucky constants because only universes with lucky constants ever can be observed.

It will never be possible to observe the existence of other universes directly. However, physical theories that predict their existence may also make predictions about the character of our own universe that can be tested. If such predictions are made, and if the observations bear out the theory, scientists will consider it likely that a multiverse exists—probably an infi -nite foam of universes originating from an infi nite number of big bangs from eternity to eternity, a few, by chance, having constants that allow matter to form galaxies, stars, planets, and intelligent observers like ourselves. However, as of 2008 there was still no physical evidence for the existence of a mul-tiverse, and the multiverse idea and the anthropic argument were disputed by many physicists.

big bang many trillions of years from now, for example, or the universe may be annihilated by a “big rip” caused by unbounded growth of dark energy. These ideas and others have been proposed, and all have supporters and detractors. Therefore, there is still no consensus view among cosmologists, as of 2008, of the universe’s ul-timate fate. Several cosmological theories have been of-fered as alternatives to the big bang, and these are taken seriously by scientists, but so far none has shown the big bang model’s fruitfulness in correctly predicting cos-mic observations. Most cosmologists are convinced that some version of the big bang (including early expansion) is correct.

Modern Cultural Connections ■

Scientifi c cosmology has, in the last half century, given at least partial answers to questions that for thousands of years addressed by religious creation myths: What is the universe, how big is it, and how is it shaped? When did it begin, and how long ago? The big bang model, which has been strongly supported by recent observa-tions, replies that the universe is an expanding, fi nite, unbounded volume of space containing a mixture of ordinary matter, dark matter, and dark energy that came into being about 13.7 billion years ago. In the beginning it was much smaller than today—sub-atomic in size—and in a state of extremely high temperature and density. The big bang was, however, not an ex-panding event in space: It was an expansion of space itself.

Since the big bang, the universe has spread out and cooled. Stars and galaxies have coalesced under the pull of gravity. Heavier elements have been welded together in stellar explosions and expelled into space and have re-coalesced into second- and third-generation stars. Hu-man beings have evolved on a planet orbiting one such third-generation star in a typical galaxy. There are over 100 billion galaxies in the observable universe; most galaxies contain several hundred billion stars.

Although many or most religious believers around the world accept all of these statements, which are sup-ported by multiple, independent, convergent lines of sci-entifi c evidence, some persons have found it diffi cult to adjust to confl icts between modern big bang cosmology and ancient cosmologies based upon religious beliefs or cultural traditions. The most prominent group of this type in the industrialized world is that of the creation-ists. All creationists deny at least some part of the sci-entifi c account of biological evolution. Many, termed young earth creationists, also deny that the universe is ancient (13.7 billion years for the whole universe, 4.5 billion years for Earth itself), preferring a much shorter chronology derived from their interpretation of the Hebrew Bible (which Christians term the Old Testa-ment). On the basis of this interpretation they affi rm the rapid, miraculous creation of the world from nothing-ness about 6,000–10,000 years ago. Some young earth creationists have attacked the big bang theory, arguing that it is fatally fl awed, contradicted by evidence, and doubted even by many astronomers. However, these claims are not scientifi cally or historically accurate. The age of the universe and its origin in a big bang-type event are attested by many forms of physical evidence.

Political, legal, theological, and social struggles be-tween young earth creationists and other persons con-tinue, primarily in the United States, but increasingly in other countries such as Australia, Germany, Turkey, and the United Kingdom. Although these struggles often focus primarily on biological evolution, big bang



cosmology and its explanation of the great age of the universe are also frequently attacked by advocates of creationism.

Ironically, although some religious believers now view modern cosmology as a challenge to their beliefs, in the mid-twentieth century some scientists original-ly viewed the big bang theory with suspicion because it seemed to bear an uncomfortable resemblance to the Genesis account of sudden creation from nothing. These scientists would have preferred an eternal “stat-ic” universe with no dramatic fi rst moment. However, the big bang theory does not necessarily posit the cre-ation of the universe out of true nothingness; even the uniqueness of the big bang is questioned in multiverse cosmology. The big bang is a scientifi c concept, not a religious one.

Primary Source Connection ■

One of the longest lasting and deepest confl icts in American culture has occurred over the teaching of the evolution of man in public schools. Often, scientifi c and religious communities assume opposing sides in the de-bate, which is frequently waged before wavering school boards who struggle to enact policy that refl ects the belief system of the local community as well as established sci-entifi c fact. The following newspaper article, written for the New York Times by James Glanz in 1999, describes a movement that gained notoriety in the 1990s, whereby some states called into question their schools’ curricu-lum for teaching the evolution of the entire universe.

James Glanz serves as the Baghdad bureau chief for the New York Times .

SCIENCE VS. THE BIBLE: DEBATE MOVES TO THE COSMOS Scientifi c lessons about the origins of life have long been challenged in public schools, but some Bible literalists are now adding the reigning theory about the origin of the universe to their list of targets.

Nearly overlooked in the furor over the Kansas school board’s vote in August to remove evolution from its ed-ucation standards was a decision on the teaching of the science of the cosmos. Infl uenced by a handful of scien-tists whose literal faith in the Bible has helped convince them that the universe is only a few thousand years old, the board deleted from its standards a description of the Big Bang theory of cosmic origins, the central organiz-ing principle of modern astronomy and cosmology.

The Big Bang theory, based on decades of astronomi-cal observations and physics research, suggests that the universe originated in a colossal explosion of matter and radiation some 15 billion years ago.

But “young Earth creationists,” as they are generally known, have come up with their own theories to ex-plain how cosmic history could be condensed into mere thousands of years. They are making this case in books, pamphlets and lectures, as well as on a number of Web sites.

Mainstream scientists consider their theories to be wildly out of line with reality, even though books describing them are often liberally sprinkled with references to au-thorities like Albert Einstein and Stephen Hawking.

As a result, physical scientists now fi nd themselves in a fi ght in which they have seldom played a public role. They have responded with a mixture of disdain, disbe-lief and consternation, and the reactions have not been limited to physicists and cosmologists in Kansas.

“It’s the denial of what understanding we have of the origin of the universe in terms of modern science,” said Jerome Friedman, a physicist at the Massachusetts In-stitute of Technology who was awarded a Nobel Prize in 1990 for collaborating in the discovery of the sub-atomic particles called quarks and is the president of the American Physical Society. “That’s a terrible loss,” Dr. Friedman said.

Hume A. Feldman, a cosmologist at the University of Kansas in Lawrence who has worked at Princeton Uni-versity and the Canadian Institute for Theoretical As-trophysics, called the matter “frightening.”

“When I went into cosmology,” Dr. Feldman said, “I never thought I would get involved in anything like that.”

Dr. Feldman said that developments in his state bore a distant resemblance to the diffi culties of political scien-tists under Communist regimes in Eastern Europe, and that he feared that such pressures could impair the edu-cational system.

But advocates of the creationist view say alarm over their theories is overblown. Steve Abrams, a member of the Kansas board and a veterinarian in Arkansas City who was among the leaders of the push to make the changes, said there were legitimate scientifi c doubts about whether the universe was more than several thou-sand years old.

“There is suffi cient data to lend credibility to the idea that we do not have all the answers for teaching the ori-gin of our universe,” he said.

That sentiment was echoed by John W. Bacon, a board member from Olathe who also voted with a narrow 6–4 majority for the changes.

“I can’t understand what they’re squealing about,” Mr. Bacon said of scientists who oppose the board’s ac-tion. Millions or billions of years ago, Mr. Bacon said, “I wasn’t here, and neither were they. Based on that, whatever explanation they may arrive at is a theory and it should be taught that way.”



Those objections closely mirror criticisms leveled at evo-lution by its opponents. Alabama biology textbooks, for example, must carry a warning that reads in part: “No one was present when life fi rst appeared on earth. Therefore, any statement about life’s origins should be considered as theory, not fact.”

The Kansas challenge to the teaching of the Big Bang is not the fi rst public objection to the theory on reli-gious or political grounds. Three years ago, the school superintendent of a conservative county in western Ken-tucky ordered two pages that explained the Big Bang in grade-school textbooks to be glued together. The superintendent said that the Big Bang should not have been explained without including the biblical version of creation as well.

The change in the Kansas standards does not preclude the teaching of mainstream biology, physics or cosmol-ogy, allowing teachers to present alternative viewpoints if they choose to do so. But because the standards are used as the basis for state tests, the changes will probably have a practical effect on what is taught, said Dr. Bill Wagnon, a professor of history at Washburn University in Topeka and a board member who voted in the mi-nority. Students’ scores on those tests help determine whether a school receives accreditation from the state.

“The curriculum standards describe that process of what needs to be covered,” Dr. Wagnon said.

So radical were the Kansas board’s recommendations that it has been unable to publish its own standards, or even to display them on its Web site. That is because the standards include long extracts from a book on educa-tion standards that was published by the National Re-search Council. Because of its disapproval of the board’s revised standards, the Council has refused permission for them to be reprinted.

Beyond the expunging of evolution, the board also took out references to the hundreds of millions of years of Earth’s geologic ages and modifi ed sections on using the slow decay of radioactive elements to measure the ages of fossils and other rocks.

Among the most striking changes was the removal of passages in the original standards dealing with the Big Bang. Cosmologists see ample evidence for that explo-sion in the present expansion of the Universe, in a dif-fuse afterglow in space called the cosmic background ra-diation, and in the precise abundances of light elements like hydrogen and helium that were left over from the cataclysm.

Cosmologists have also calculated the way in which stars, galaxies and clusters of galaxies coalesced from slight ripples in the primordial soup that emerged from the big bang. To date, the results of those calculations match the precise observations of such structures in the

heavens. Of course, for all its success in accounting for observations, the Big Bang is indeed just a theory, al-though it is one with few scientifi c dissenters.

The biggest problem for the young Earth creationists is explaining the time that has apparently passed since the light we see from distant galaxies was emitted. Given the constancy of the speed of light and estimates of the distance between Earth and faraway galaxies it is dif-fi cult to explain how Earth and the cosmos could be young.

But D. Russell Humphreys, a nuclear weapons engineer at Sandia National Laboratory who is also an adjunct professor at the Institute for Creation Research near San Diego, thinks he has an answer. In an interview, he said that Einstein’s equations of relativity, the ba-sis of the Big Bang theory, could be used to construct a universe in which the Earth is only a few thousand years old.

Dr. Abrams said that in thinking about the Kansas stan-dards he had been struck by Dr. Humphreys’s book, “Starlight and Time: Solving the Puzzle of Distant Star-light in a Young Universe” (Master Books, fi fth printing in 1998).

Dr. Humphreys’s ideas “seem to be right there on the cutting edge, so to speak,” Dr. Abrams said.

But most cosmologists say they are simply out of left fi eld.

The theory relies on a peculiar feature of Einstein’s equations, which predict that powerful gravitational fi elds can speed the progress of time and, in effect, make clocks run at different rates in different places. So Dr. Humphreys assumes that the Earth is close to the center of a structure related to a black hole, in which gravity is especially intense, so that billions of years could pass in deep space while only a few thousand years went by on Earth.

Such a universe “has clocks clicking at drastically differ-ent rates in different parts,” Dr. Humphreys said in an interview.

Dr. Edward L. Wright, vice chairman for astronomy at the University of California at Los Angeles, said that there is no evidence that the Earth is at the center of the universe, or that such tremendous gravitational fi elds exist outside of ordinary black holes.

Moreover, Dr. Wright said, the acceleration of time would alter the vibrations of waves of light, shorten-ing its wave length and turning it into deadly gamma rays. Bombarded by such radiation, he said, “the Earth would be sterilized.”

Dr. Humphreys, whose research in cosmology is unre-lated to his work at the lab, said other features of his model would prevent the frequency increase.



Dr. Abrams also cited a theory that the speed of light was almost infi nitely fast in the past, meaning that the light from distant galaxies could have reached Earth quickly and would not be billions of years old.

He referred to writings on this subject by Dr. Danny Faulkner, a professor of astronomy at the University of South Carolina’s Lancaster campus and an adjunct pro-fessor at the Institute for Creation Science. In a tele-phone interview, Dr. Faulkner cautioned that he had merely been describing ideas put forth by other scien-tists in the creationist movement and was not certain that the changing speed of light was correct. Indeed, high-precision measurements of the speed of light and other crucial physical constants have revealed no detect-able change in their values over recent time.

The debate over the age of the universe has exposed in-tense disagreements not just in schools but also among evangelical Christians.

“Often young-universe and old-universe creationists fo-cus more energy on defending their respective positions than on reaching out to nonbelievers,” wrote Dr. Hugh Ross, a former radioastronomer who is an evangelical Christian, in “Creation and Time: A Biblical and Sci-entifi c Perspective on the Creation-Date Controversy” (NavPress, 1994).

Dr. Ross thinks that a literal reading of the Bible can be reconciled with the Big Bang, but says that his views are distinctly in the minority among evangelical Christians. The six days of Genesis could stand for “six consecutive long periods of time,” Dr. Ross said.

The importance of the issue for many Bible literalists means that cosmologists could face the pressures that biologists have dealt with since John Scopes was con-victed of violating a Tennessee law against the teaching of evolution in 1925, said Dr. Eugenie C. Scott, execu-tive director of the National Center for Science Educa-tion Inc., in El Cerrito, Calif.

“I don’t think physical scientists are going to be im-mune to this,” Dr. Scott said. “It would be very unwise for them to brush this off.”

James Glanz

GL A NZ , JA M E S. “SCI ENCE VS. T H E BI BL E:

DEBAT E MOV E S TO T H E COSMOS.” N EW Y OR K T I M ES

(OCTOBER 10, 1999).

SEE ALSO Astronomy and Cosmology: Cosmology; Astronomy and Cosmology: Setting the Cosmic Cal-endar: Arguing the Age of the Cosmos and Earth; Physics: Special and General Relativity.

B I B L I O G R A P H Y

Books

Weinberg, Steven. The First Three Minutes . New York: Basic Books, 1988.

Periodicals

Bennett, Charles L. “Cosmology from Start to Finish.” Nature . 440 (2006): 1126–1131.

Cho, Adrian. “Gravity Distorts Big Bang Afterglow, Opening New Window on Cosmos.” Science . 316 (2007): 1407.

Cowan, John J., and Christopher Sneden. “Heavy Ele-ment Synthesis in the Oldest Stars and the Early Universe.” Nature . 440 (2006): 1151–1156.

Glanz, James. “Science vs. the Bible: Debate Moves to the Cosmos.” New York Times (October 10, 1999).

Hogan, Craig J. “The Beginning of Time.” Science . 295 (2002): 2223–2225.

Web Sites

National Aeronautics and Space Administration (U.S.). “Cosmology: The Study of the Universe.” Sep-tember 26, 2006. http://map.gsfc.nasa.gov/m_uni.html (accessed February 6, 2008).

Larry Gilman

astronomy and cosmology: big bang theory and modern …astronomy and cosmology: big bang theory and...

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