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About the Author
Hubert Reeves is an astrophysicist who has worked as an advisor for NASA and as director of the Centre National de la Recherche Scientifique. He lives in France.
Dominique Simonnet is a journalist and author. He lives in France.
Joel de Rosnay is the former director of the famed Pasteur Institute and is currently president of Biotics International, a major consulting company that specializes in the impact of new technologies on industries. He lives in France.
Read an Excerpt
The stage is white, infinite. Everywhere, there is nothing but an implacable clarity, the light of an incandescent universe, the chaos of a matter that as yet has neither meaning nor name. ...
But What Was There "Before"?
DS: An explosion of light back in the furthest reaches of time is where our story begins, the origin of the universe, which science has been focusing on and speculating about over the past several years. Before we can consider that phenomenon, however, we have to stop and ask ourselves this naive question: what was there before?
HR: When you bring up the subject of the beginning of the universe, you inevitably come up against a problem of vocabulary. For us, the word "origin" relates to an event that can be situated in time. Our personal "origin," for example, is the moment when our parents conceived us. That origin has both a "before" and an "after." We can date it, note it down specifically in the context of our personal story. And we are willing to accept the fact that the world existed before we came into it.
But here we're talking about the origin of origins, the very first ...
And therein lies the great difference. The origin to which we're referring, the beginning of the beginning, cannot be thought of as an event comparable to any other. We find ourselves in the same situation as the early Christians, who kept asking what God was doing before He created the world. The popular response in those days was: "He was busy preparing hell for all the people who ask that question!" Saint Augustine did not agree. He clearly saw the inherent difficulty in such a question, which presupposed that time existed before the Creation. His answer was that Creation was not only the beginning of matter but also the beginning of time. That point of view is very close to what science is saying today. Space, matter, energy, and time are all inextricably intertwined, indissoluble. In our cosmologies, they appear together. If there is an origin of the universe, then that is also when time began. Therefore, there is no "before."
"If there is an origin of the universe," you say. Which implies that there's some doubt about it.
The major discovery of the twentieth century is that the universe is neither immutable nor eternal, as most scientists believed in the past. Today we are convinced of that notion: the universe has a history, it has constantly, endlessly evolved, become rarefied, grown cooler, become more structured. Both our observations and our theories allow us to go back in time and reconstruct the story of how the universe has evolved. Those observations and theories confirm that this evolution has been going on for a very, very long time: somewhere between fourteen and fifteen billion years, according to the best estimates. We now have at our disposal a sufficient number of scientific elements to describe what the universe was like at that time: it was completely disorganized; there were no galaxies or stars, no molecules or atoms or even the nuclei of atoms. It was nothing more than a kind of thick puree, a formless, pasty soup, with temperatures in the billions and billions of degrees.
And nothing before?
We don't have any knowledge of what preceded that event, not even the faintest clue that would enable us to delve deeper into the past. All the observations, all the data gathered by astrophysicists stop at that same frontier. Does that mean that the universe "began" fifteen billion years ago? Does it mean that the Big Bang is really the origin of the origin? We have no idea.
And yet that is what students are being taught in school today: the universe began with a Big Bang roughly fifteen billion years ago. And that, in fact, is what scientists have been telling us over and over again for many years now.
We probably didn't express ourselves clearly enough, and we've been misunderstood. We could speak about a beginning, a veritable first moment, if we were sure that there was nothing before. The fact is, at those high temperatures, our notions of time, space, energy, of temperature itself, no longer apply. Our laws no longer function; we are completely stripped bare.
When you say that, aren't you — scientists in general — begging the question, copping out? When we tell a story, there's always a beginning. Since our subject here is the "story" of the universe, it's not all that unreasonable for us to go looking for the point when it all began.
Of course, in the human context, all stories do have a beginning. But we have to beware of extrapolations. We can say the same thing about Voltaire's clock: the very existence of the clock, he maintained, proved the existence of a clock maker. Does this reasoning, however unassailable at our level, the human scale, really apply to the "clock" of the universe? I'm far from sure that it does. What we have to consider is whether or not our logic, as Heidegger said, is the supreme instance, if the assertions and arguments that are valid here on Earth can be fairly applied to the universe in its entirety. The only real question is that of our existence, that of reality, of our consciousness: "Why is there something rather than nothing?" Leibniz asked. But that is a purely philosophical question, which science is incapable of answering.
The Horizon of Our Knowledge
To get around this brainteaser, could we therefore define the Big Bang as the beginning of space and time?
Let's rather define it as the moment when these notions became usable. In reality, the Big Bang is our horizon in time and in space. If we assume that that is the point zero of our story, it's for the sake of convenience; it's because we have nothing better to go on. We're like the early explorers facing the vast ocean: we can't see whether there's anything beyond the distant horizon.
If I understand correctly, the Big Bang is in fact a manner of designating not actually the limit of the world but the limit of our knowledge.
Precisely. But be careful: having said that, we cannot therefore go on to conclude that the universe does not have an origin. Once again, we simply don't know. But for the sake of argument, and to simplify the question, let us assume that our adventure began fifteen billion years ago, in this infinite and unformed chaos that will slowly structure itself. That, in any case, is the beginning of our story of the world such as science can reconstitute it today.
Specialists can make do with an abstraction to portray the Big Bang. But we laymen need a metaphor. We've often heard it described as a ball of concentrated matter that exploded in an enormous burst of light and filled the entire space.
Because some scientists describe it that way does not mean it's right. That explanation would presuppose the existence of two spaces: one filled with matter and light that progressively invade a second space, which is empty and cold. In the model of the Big Bang, only one space is produced, uniformly filled with light and matter that are expanding in every direction: all its points are moving away from one another at the same speed.
It's difficult to conceive. Is there some kind of visual description you can give the Big Bang?
You can, in a pinch, imagine an enormous explosion, but only if you can accept the notion that the explosion is occurring in each and every point of a vast and perhaps (but not certainly) infinite space. Of course, that's extremely difficult to imagine, but is there anything so surprising about it? When we grapple with such matters on such a scale, our intellectual powers find themselves in unusual, uncharted territories, and our descriptions are of necessity inadequate at best.
Infinite or not, that image corresponds very nicely to the Bible's description of the creation of the world. "And there was light. ..."
That striking similarity actually worked against the acceptance of the Big Bang theory when it was first proposed in the early 1930s, especially after the statements made by Pope Pius XII that science had rediscovered Fiat Lux, "Let there be light," and thus validated the Bible's description of the Creation. In Moscow at the same time, the Communists' attitude was also revealing. At first they completely dismissed the pope's pronouncements as "papal stupidities"; then they realized that this idea could serve to validate and confirm the Communist dogma of "historical materialism." So there was a rapid shift in the party line, and Lenin was given credit for having foreseen the discovery Nonetheless, despite all these attempts by both religious and political groups to co-opt the idea for their own ends, the theory prevailed. In the course of the following decades, proof after proof piled up, and virtually all astrophysicists came to accept the theory as the best explanation of the history of the cosmos. One exception is the English astrophysicist Fred Hoyle; he continues to maintain that the universe is stationary. Ironically, it was he who derisively baptized the theory the "Big Bang," and the term stuck.
* * *
That science meets religion along its way is not so terrible, is it?
So long as one makes sure not to confuse their different approaches. Science seeks to understand the world; religions generally view their mission as trying to give life a meaning. They can each shed light on the other, but only so long as they both remain in their own territory. Each time the church has tried to impose its explanation on the world, there has been a conflict. Remember what Galileo said to the theologians who set themselves up against him: "You. can tell us how to gain entrance into heaven. Let us scientists tell you how things are faring in the heavens above." Remember, too, the staunch opposition of the church fathers to Darwin's theories. Science is concerned with measurable, deducible facts. It does not attempt to deal with what might exist beyond the visible world, the measurable. Contrary to popular opinion, science does not set itself up in opposition to God. Science can neither prove nor disprove His existence. That subject transcends the limits of science.
Despite all you say, not only Christianity but also several other religions and mythologies explain the creation of the world by an explosion of light. Don't you find that disturbing?
The image of an initial chaos that progressively transformed itself into an organized universe does indeed occur in a number of traditional versions of how the world began. We find it in the writings of the Egyptians, in the oral traditions of the North American Indians, among the stories of the ancient Sumerians.
This chaos is often depicted by an aquatic image, for instance, an ocean in darkness. "Nothing existed except the empty sky above and the calm sea below, in the depths of night," according to the Mayan tradition. "And the entire Earth was nothing but sea," says a Babylonian text. And Genesis: "And the Earth was without form, and void; and darkness was upon the face of the deep. And the spirit of God moved upon the face of the water." The metaphor of the egg was also used. Inside the egg, a seemingly formless liquid is transformed into a baby chick. It's a lovely image of the evolution of the universe. Among the Chinese, the egg separates into two halves, one of which becomes the heavens, the other Earth. Still, in all these mythological descriptions, chaos is associated with water and darkness. In modern cosmology, chaos is made of heat and light.
And yet these analogies between the scientific description and early myths are undeniable.
Could it be a matter of pure coincidence? Or the result of some intuitive knowledge? After all, as we shall see in the course of our story, we ourselves are made up of the dust of the Big Bang. Could it be that we bear within ourselves the memory of the universe?
The Discovery of History
How did science happen to propound the idea of an original chaos and the evolution of the universe?
For two thousand years, philosophical tradition had it that the universe was eternal and unchanging. Aristotle expressed himself very clearly on the subject, and his ideas dominated Western thought for more than two thousand years. According to him, the stars were made of unperishable matter, and the heavenly map was fixed and unchanging. Today, thanks to modern instruments, we know that Aristotle was wrong. Stars are born and die, after having lived for millions or even billions of years. They shine, consuming their nuclear fuel, and when it is used up, they go out, disappear. We can even date them.
No one ever came up with the idea, early in human history, that the heavens could change?
Actually, some did. Several philosophers suggested as much, but their views never took hold. Lucretius, the Roman philosopher who lived in the first century before Christ, asserted that the universe was still in its youth. How did he arrive at that notion, which was so far ahead of its time? He followed a very clever line of reasoning. Since I was a child, he said to himself, I've noticed all around me that improvements have been made in various areas. We've improved the sails of our ships, so that they sail faster; we've invented weapons that are more efficient; we've invented musical instruments that are more and more sophisticated. If the universe were eternal, all these changes and improvements would have had time to occur a hundred times over, a thousand times, millions of times! In which case I would be living in a finished world, which no longer changed. But the fact is, during the brief years of my own life I've witnessed so many improvements that it proves that the world has not always existed.
A pretty solid piece of deduction.
Today, cosmology confirms Lucretius's notion on three grounds: (1) the world has not always existed, (2) it is constantly changing, and (3) this change is expressed by the movement from less efficient to more efficient, that is, from the simple to the complex.
Going Back in the Time Machine
Modern science is founded on what discoveries?
Thanks to our instruments — instruments of both physics and astrophysics — we have been able to discover traces of the universe's past. We can reconstitute its history in the same way anthropologists can reconstitute humankind's past from fossils found in sedimentary layers that later become exposed through tectonic shifts, weathering, and so forth. But we have an enormous advantage over students of prehistory: we can actually see the past.
Could you clarify that?
In our scale, light travels very fast: the speed of light, as we all know, is 300,000 kilometers — 186,000 miles — per second. On the scale of the universe, this speed is very low. Light comes to us from the Moon in roughly a second. Light from the Sun reaches us in eight minutes. But from the closest star it takes four years; light from Vega takes eight years, and from certain galaxies it takes billions of years. Modern-day telescopes enable us to observe very distant stars, quasars, for example, the luminosity of which can be as much as ten thousand times that of our entire galaxy. Some of those quasars are located twelve billion light-years away from us. In other words, we're seeing them today the way they were twelve billion years ago.
Whenever you focus your telescope on any given region of the universe, what you're really doing is observing a moment of its history.
That's exactly right. The telescope is an instrument that allows us to go back in time. In contrast to historians, who can never actually see Rome the way it was in its glory, we astrophysicists can truly see the past and observe stars the way they were. We see the Orion Nebula the way it was at the end of the Roman Empire. And the galaxy of Andromeda, visible by the naked eye, is an image that's two million years old. If the people who dwell in the Andromeda galaxy were looking at planet Earth today, what they'd be seeing would be the time of prehistoric man.
All of which means that the sky we gaze upon at night, the stars we see, the myriad stars and galaxies, are really only so many illusions, the superimposition of past images.
Strictly speaking, we can never see the present state of the world. When I look at you, I'm seeing you as you were a hundredth of a microsecond ago, the time it takes for light to reach me. A hundredth of a microsecond is very long on the atomic scale, even though it's imperceptible to our minds. But human beings do not disappear in that lapse of time, so I can hypothesize without risk that you are still there. The same goes for the Sun: it does not change during the eight minutes it takes its light to reach Earth. The stars we see at night with the naked eye, the stars in our own galaxy, are also relatively close. But for the distant stars, those that we can detect only with the most powerful telescopes, it's a whole other matter. The quasar that I see at twelve billion light-years' distance in all likelihood does not exist today.
Would it be possible, therefore, to go even further back in time, to that famous "horizon" when the Big Bang took place?
* * *
The further back we go into the past, the more opaque the universe becomes. Beyond a certain limit, light can no longer reach us. That horizon corresponds to a time when the temperature was roughly three thousand degrees Celsius. According to the conventional time clock based on the Big Bang, the universe would then already be about 300,000 years old.(Continues…)
Excerpted from "Origins"
Copyright © 2011 Editions du Seuil.
Excerpted by permission of Skyhorse Publishing.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
Act 1 The Universe 11
Scene 1 Chaos 13
Scene 2 The Universe Gets Organized 35
Scene 3 Earth 53
Act 2 Life 71
Scene 1 The Primitive Soup 73
Scene 2 Life Gets Organized 89
Scene 3 The Explosion of the Species 109
Act 3 Mankind 135
Scene 1 The African Cradle 137
Scene 2 Our Ancestors Get Organized 157
Scene 3 The Human Conquest 175