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Authors: Neil deGrasse Tyson,Donald Goldsmith

Origins: Fourteen Billion Years of Cosmic Evolution

BOOK: Origins: Fourteen Billion Years of Cosmic Evolution
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Also by Neil deGrasse Tyson

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Worlds Unnumbered: The Search for Extrasolar Planets

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Fourteen Billion Years of
Cosmic Evolution

Neil deGrasse Tyson


Donald Goldsmith



To all those who look up,
And to all those who do not yet know
why they should



        A Meditation on the Origins of Science and the Science of Origins

      The Greatest Story Ever Told

Part I: The Origin of the Universe

    In the Beginning

    Antimatter Matters

    Let There Be Light

    Let There Be Dark

    Let There Be More Dark

    One Universe or Many?

Part II: The Origin of Galaxies and Cosmic Structure

    Discovering Galaxies

    The Origin of Structure

Part III: The Origin of Stars

    Dust to Dust

  The Elemental Zoo

Part IV: The Origin of Planets

  When Worlds Were Young

  Between the Planets

  Worlds Unnumbered: Planets Beyond the Solar System

Part V: The Origin of Life

  Life in the Universe

  The Origin of Life on Earth

  Searching for Life in the Solar System

  Searching for Life in the Milky Way Galaxy

          The Search for Ourselves in the Cosmos

Glossary of Selected Terms

Further Reading

Image Credits


Photo Insert


For reading and rereading the manuscript, ensuring that we mean what we say and say what we mean, we are indebted to Robert Lupton of Princeton University. His tandem expertise in astrophysics and the English language allowed the book to reach several notches higher than we had otherwise imagined for it. We are also grateful to Sean Carroll at Chicago’s Fermi Institute, Tobias Owen of the University of Hawaii, Steven Soter of the American Museum of Natural History, Larry Squire of UC San Diego, Michael Strauss of Princeton University, and PBS NOVA
producer Tom Levenson for key suggestions that improved several parts of the book.

For expressing confidence in the project from the beginning, we thank Betsy Lerner of the Gernert Agency, who saw our manuscript not only as a book but also as an expression of deep interest in the cosmos, deserving the broadest possible audience with whom to share the love.

Major portions of Part II and scattered portions of Parts I and III first appeared as essays in
Natural History
magazine by NDT. For this, he is grateful to Peter Brown, the magazine’s editor in chief, and especially to Avis Lang, their senior editor, who continues to work heroically as a learned literary shepherd to NDT’s writing efforts.

The authors further recognize support from the Sloan Foundation in the writing and preparation of this book. We continue to admire their legacy of support for projects such as this.

Neil deGrasse Tyson, New York City

Donald Goldsmith, Berkeley, California

June 2004


A Meditation on the Origins of Science and the Science of Origins

new synthesis of scientific knowledge has emerged and continues to flourish. In recent years, the answers to questions about our cosmic origins have not come solely from the domain of astrophysics. Working under the umbrella of emergent fields with names such as astrochemistry, astrobiology, and astro-particle physics, astrophysicists have recognized that they can benefit greatly from the collaborative infusion of other sciences. To invoke multiple branches of science when answering the question, Where did we come from? empowers investigators with a previously unimagined breadth and depth of insight into how the universe works.

Origins: Fourteen Billion Years of Cosmic Evolution
, we introduce the reader to this new synthesis of knowledge, which allows us to address not only the origin of the universe but also the origin of the largest structures that matter has formed, the origin of the stars that light the cosmos, the origin of planets that offer the likeliest sites for life, and the origin of life itself on one or more of those planets.

Humans remain fascinated with the topic of origins for many reasons, both logical and emotional. We can hardly comprehend the essence of anything without knowing where it came from. And of all the stories that we hear, those that recount our own origins engender the deepest resonance within us.

Self-centeredness bred into our bones by our evolution and experience on Earth has led us naturally to focus on local events and phenomena in the retelling of most origin stories. However, every advance in our knowledge of the cosmos has revealed that we live on a cosmic speck of dust, orbiting a mediocre star in the far suburbs of a common sort of galaxy, among a hundred billion galaxies in the universe. The news of our cosmic unimportance triggers impressive defense mechanisms in the human psyche. Many of us unwittingly resemble the man in the cartoon who gazes at the starry heavens and remarks to his companion, “When I look at all those stars, I’m struck by how insignificant they are.”

Throughout history, different cultures have produced creation myths that explain our origins as the result of cosmic forces shaping our destiny. These histories have helped us to ward off feelings of insignificance. Although origin stories typically begin with the big picture, they get down to Earth with impressive speed, zipping past the creation of the universe, of all its contents, and of life on Earth, to arrive at long explanations of myriad details of human history and its social conflicts, as if we somehow formed the center of creation.

Almost all the disparate answers to the quest of origins accept as their underlying premise that the cosmos behaves in accordance with general rules, which reveal themselves, at least in principle, to our careful examination of the world around us. Ancient Greek philosophers raised this premise to exalted heights, insisting that we humans possess the power to perceive how nature operates, as well as the underlying reality beneath what we observe: the fundamental truths that govern all else. Quite understandably, they insisted that uncovering those truths would be difficult. Twenty-three hundred years ago, in his most famous reflection on our ignorance, the Greek philosopher Plato compared those who strive for knowledge to prisoners chained in a cave, unable to see objects behind them, and who must attempt to deduce from the shadows of these objects an accurate description of reality.

With this simile, Plato not only summarized humanity’s attempts to understand the cosmos but also emphasized that we have a natural tendency to believe that mysterious, dimly sensed entities govern the universe, privy to knowledge that we can, at best, glimpse only in part. From Plato to Buddha, from Moses to Mohammed, from a hypothesized cosmic creator to modern films about “the matrix,” humans in every culture have concluded that higher powers rule the cosmos, gifted with an understanding of the gulf between reality and superficial appearance.

Half a millennium ago, a new approach toward understanding nature slowly took hold. This attitude, which we now call science, arose from the confluence of new technologies and the discoveries that they fostered. The spread of printed books across Europe, together with simultaneous improvements in travel by road and water, allowed individuals to communicate more quickly and effectively, so that they could learn what others had to say and could respond far more rapidly than in the past. During the sixteenth and seventeenth centuries, this hastened back-and-forth disputation and led to a new way of acquiring knowledge, based on the principle that the most effective means of understanding the cosmos relies on careful observations, coupled with attempts to specify broad and basic principles that explain a set of these observations.

One more concept gave birth to science. Science depends on organized skepticism, that is, on continual, methodical doubting. Few of us doubt our own conclusions, so science embraces its skeptical approach by rewarding those who doubt someone else’s. We may rightly call this approach unnatural; not so much because it calls for mistrusting someone else’s thoughts, but because science encourages and rewards those who can demonstrate that another scientist’s conclusions are just plain wrong. To other scientists, the scientist who corrects a colleague’s error, or cites good reasons for seriously doubting his or her conclusions, performs a noble deed, like a Zen master who boxes the ears of a novice straying from the meditative path, although scientists correct one another more as equals than as master and student. By rewarding a scientist who spots another’s errors—a task that human nature makes much easier than discerning one’s own mistakes—scientists as a group have created an inborn system of self-correction. Scientists have collectively created our most efficient and effective tool for analyzing nature, because they seek to disprove other scientists’ theories even as they support their earnest attempts to advance human knowledge. Science thus amounts to a collective pursuit, but a mutual admiration society it is not, nor was meant to be.

Like all attempts at human progress, the scientific approach works better in theory than in practice. Not all scientists doubt one another as effectively as they should. The need to impress scientists who occupy powerful positions, and who are sometimes swayed by factors that lie beyond their conscious knowledge, can interfere with science’s self-correcting ability. In the long run, however, errors cannot endure, because other scientists will discover them and promote their own careers by trumpeting the news. Those conclusions that do survive the attacks of other scientists will eventually achieve the status of scientific “laws,” accepted as valid descriptions of reality, even though scientists understand that each of these laws may some day find itself to be only part of a larger, deeper truth.

But scientists hardly spend all their time attempting to prove one another mistaken. Most scientific endeavors proceed by testing imperfectly established hypotheses against slightly improved observational results. Every once in a while, however, a significantly new take on an important theory emerges, or (more often in an age of technological advances) a whole new range of observations opens the way to a new set of hypotheses to explain these new results. The greatest moments in scientific history have arisen, and will always arise, when a new explanation, perhaps coupled with new observational results, produces a seismic shift in our conclusions about the workings of nature. Scientific progress depends on individuals in both camps: those who assemble better data and extrapolate carefully from it; and those who risk much—and have much to gain if successful—by challenging widely accepted conclusions.

Science’s skeptical core makes it a poor competitor for human hearts and minds, which recoil from its ongoing controversies and prefer the security of seemingly eternal truths. If the scientific approach were just one more interpretation of the cosmos, it would never have amounted to much; but science’s big-time success rests on the fact that it works. If you board an aircraft built according to science—with principles that have survived numerous attempts to prove them wrong—you have a far better chance of reaching your destination than you do in an aircraft constructed by the rules of Vedic astrology.

Throughout relatively recent history, people confronted with the success of science in explaining natural phenomena have reacted in one of four ways. First, a small minority have embraced the scientific method as our best hope for understanding nature, and seek no additional ways to comprehend the universe. Second, a much larger number ignore science, judging it uninteresting, opaque, or opposed to the human spirit. (Those who watch television greedily without ever pausing to wonder where the pictures and sound come from remind us that the words “magic” and “machine” share deep etymological roots.) Third, another minority, conscious of the assault that science seems to make upon their cherished beliefs, seek actively to disprove scientific results that annoy or enrage them. They do so, however, quite outside the skeptical framework of science, as you can easily establish by asking one of them, “What evidence would convince you that you are wrong?” These anti-scientists still feel the shock that John Donne described in his poem “The Anatomy of the World: The First Anniversary,” written in 1611 as the first fruits of modern science appeared:

And new philosophy calls all in doubt,

The element of fire is quite put out,

The Sun is lost, and th’earth, and no man’s wit

Can well direct him where to look for it.

And freely men confess that this world’s spent,

When in the planets and the firmament

They seek so many new; they see that this [world]

Is crumbled out again to his atomies.

’Tis all in pieces, all coherence gone . . .

Fourth, another large section of the public accepts the scientific approach to nature while maintaining a belief in supernatural entities existing beyond our complete understanding that rule the cosmos. Baruch Spinoza, the philosopher who created the strongest bridge between the natural and the supernatural, rejected any distinction between nature
God, insisting instead that the cosmos is simultaneously nature and God. Adherents of more conventional religions, which typically insist on this distinction, often reconcile the two by mentally separating the domains in which the natural and the supernatural operate.

No matter what camp you may live in, no one doubts that these are auspicious times for learning what’s new in the cosmos. Let us then proceed with our adventurous quest for cosmic origins, acting much like detectives who deduce the facts of the crime from the evidence left behind. We invite you to join us in search of cosmic clues—and the means of interpreting them—so that together we may uncover the story of how part of the universe turned into ourselves.

BOOK: Origins: Fourteen Billion Years of Cosmic Evolution
5.41Mb size Format: txt, pdf, ePub

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