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SHOW 105 TRANSCRIPT
When and How Did This Universe Begin?

THE creation question is humanity's ancient and perpetual fascination. When did it happen and what caused it all? We may finally be getting some real answers. Cosmology is the study of the origin and outcome of the universe, and it is a young science: its revolutionary discoveries have been relatively recent. The accepted theory is known as the Big Bang; it holds that the universe began a number of billion years ago, when an infinitesimally small point expanded majestically and cooked up space, time, energy, and matter in a colossal cosmic stew. Formulated in the middle decades of the twentieth century, the Big Bang had to compete for a while with another cosmological theory known as the Steady State universe. Steady State theory envisioned the universe as without an origin--that is, as having always existed--and as expanding while maintaining a constant average density. This theory posited the continuous creation of matter, with new stars and galaxies forming at the same rate as older ones became unobservable due to the cosmic expansion. A Steady State universe had no beginning or end in time, galaxies of all possible ages were intermingled, and the picture of the universe on a grand scale, viewed from any position, remained essentially the same with respect to the average density and arrangement of galaxies. Big Bang theorists found the continuous creation of matter an unappealing idea and preferred to have all creation concentrated in a single moment. Proponents of the Steady State argued that it eliminated the need for an unexplained beginning of the universe, and a few were gratified that it undermined the foundations of various creation-based theological models. But observational data over four decades have remarkably and consistently supported the Big Bang and laid the Steady State to rest. One of the more powerful corroborations of the Big Bang was the discovery in 1965 of the cosmic microwave background radiation, a lingering remnant of the primordial explosion, which permeates the universe at the predicted temperature of about three degrees above absolute zero. However, recent research now suggests that the Big Bang, awesomely, may have been far bigger than that: the Big Bang may have been followed immediately by a period of short-lived but exponential inflation--a theory that seems to solve a number of cosmological puzzles. There have been various versions of inflationary theory; one of them, known as chaotic inflation, proposes that the universe resembles a huge, rapidly multiplying fractal--an irregular, self-similar pattern (like clouds or coastlines) in which each part appears as a reduced-size copy of the whole. This mega-universe would consist of many separate universes (in only one of which we live), each undergoing episodes of initial inflation and producing new universes randomly, ad infinitum. Its evolution has no end--and may well have had no beginning. But how can we draw such fine-grained portraits of the universal origin? What methods can reach back over many billions of years? And how many billions? The proposed cosmic life span has been variously pegged at ten, twelve, fifteen, or twenty billion years, and cosmologists are closing in on the number. Why should we care? Because beyond just knowing--which is important enough--what happened so very long ago may carry very great meaning for human understanding today. Heated debate is still a part of cosmology, and we invited some folks who care deeply about ultimate matters to tell us why they think so hard about when and how the universe began.

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PARTICIPANTS

Dr. Wendy Freedman, an astronomer based at the Observatories of the Carnegie Institution, in Pasadena, is the principal investigator for a Hubble Space Telescope project to determine the age of the universe. Wendy takes us back to the very beginning of time and gives us the latest firm date.

Dr. Leon Lederman, a Nobel Laureate in physics, is the founder of the Illinois Mathematics and Science Academy for gifted high school students. Leon reflects on how the origin of the universe intersects with particle physics and why this is important for all of us.

Dr. Andrei Linde, a professor of physics at Stanford, is one of the originators of inflationary theory, developed while he was still in Russia. Andrei believes that the idea that the Big Bang was a single fireball is incorrect, that this observable universe is not the only one, and that as a result of a series of random inflationary episodes the universe is incomprehensibly larger than it appears.

Dr. Nancey Murphy, Theology Division chair and a professor of Christian philosophy at Fuller Theological Seminary, studies the relationship between science and religion. Nancey describes how theologians try to keep up with the rapid changes in cosmology.

Dr. Frank Tipler, a professor of mathematics and physics at Tulane, is co-author (with the British astronomer John Barrow) of The Anthropic Cosmological Principle. Frank wonders why our universe is so astonishingly well suited to bring forth life.

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ROBERT: Wendy, let's start with a number--the age of the universe. You measure distances to galaxies as a way of assessing the rate at which the universe expands. How old is the universe, and why does its expansion rate matter?

WENDY: We're finding the age of the universe to be about twelve billion years old. Expansion matters because, since we observe our universe expanding now, we know that the galaxies must have been closer together in the past; and we can rewind that picture back to the very origin of the universe, and thus see how long the universe has been expanding--and that's its age. It's like playing a movie in reverse. 

ROBERT: What methods do you use to observe this expansion? 

WENDY: We use the Hubble Space Telescope to measure the distances to galaxies. This is the first time we've been able to make these measurements above the earth's atmosphere, and to do it very precisely for a large number of galaxies. 

ROBERT: The age of the universe used to be wildly uncertain.

WENDY: That's right. The range has been something like ten billion to twenty billion years. Obviously it's difficult to measure cosmic distances; we can't use a yardstick. We have to come up with approaches that allow us to use light from galaxies. We've done the measurement five different ways, and that's how we've convinced ourselves that we understand [the confidence limits and] the uncertainties.1 

{FOOTNOTE}1 Several independent techniques are used to measure distances in the universe; each has limitations and the process can be tricky. For example, the parallax method, which can be used only for distances to close stars, is a direct calculation of a star's apparent motion against a more distant stellar background as a result of the earth's orbit around the sun. The luminosity method measures the brightness and periods of variable stars (e.g., Cepheids) and exploding stars (novae and supernovae); these are called "standard candles," in that if their absolute luminosity (energy output) is known (a key assumption), then their apparent brightness is directly related to their distances (an appropriate method for nearby galaxies, but not distant ones). The red shift method, which uses a spectrograph to assess light from rapidly receding stellar or galactic objects (Doppler effect), assumes that receding velocity is related to distance as indicated by the Big Bang theory of the expansion of the universe. {/FOOTNOTE}

ROBERT: Andrei, inflationary cosmology has been hailed as one of the most remarkable scientific theories in the history of science, extending the scope of reality beyond comprehension. How would you explain inflationary theory to a high school student?

ANDREI: Well, this is a tough one. Inflationary theory describes the very early stages of the universe, and its enormous, though short-lived, expansion. The standard Big Bang theory held that the universe began as a very, very big explosion--an expanding fireball. But then we found that this big explosion was not big enough to explain everything we see in the universe. At the end of the 1970's it was proposed that the early universe came through a stage of inflation, an exponentially rapid expansion in a kind of unstable heavy vacuum-like state (a state with large energy density but without elementary particles). A vacuum-like state in inflationary theory is usually associated with a scalar field, which is often called "the inflation field." So instead of imagining the beginning of the universe as very hot, we imagine it at the beginning as this kind of an unstable vacuum-like state that did not contain any elementary particles, but which did contain this scalar field. It is totally empty, without any particles, but still has a lot of energy. And I will be in trouble if I try to explain it in any more detail without using jargon of quantum field theory and general relativity. 

ROBERT: There's nothing but a potent sort of potential energy?

ANDREI: Yes, the potential energy of the scalar field. And then, a fraction of a second after the Big Bang, a region of this scalar field starts expanding exponentially. This is our universe, and at this stage it expands much faster than in standard Big Bang theory, and eventually--after another fraction of a second--the scalar field decays. And after that, the evolution of the universe and the formation of elementary particles can be described by standard Big Bang theory. 

ROBERT: Leon, you've helped elucidate the Standard Model of particle physics and you're a pioneer in science education in America. Why is the origin of the universe an important question for nonscientists?

LEON: Well, for one thing, the age of anything is very sensitive to me personally…. Fundamentally, almost all human beings who think at all think about origins. Where did I come from? Where did my world come from? These questions are natural--not like questions about my quarks. By the way, you stopped Andrei just as he was just about to make quarks in his universe. People are fascinated by the whole story of the universe--how we got from there to here. They also have a morbid interest in endings--where we're going. 

ROBERT: We'll get to that in the next program.

LEON: Unless we know how we started, it wouldn't make much sense to wonder where we're going. So to me, the origin of the universe is one of the easiest topics to get interested in. 

ROBERT: Frank, you're the author of two fascinating books: The Anthropic Cosmological Principle and The Physics of Immortality. Let's start with the more modest controversy--what is the anthropic principle? 

FRANK: The anthropic principle starts by saying that there are many different types of universes. Take Andrei [Linde]'s eternally inflating universes, which you spoke about in the introduction. Some of them would inflate very rapidly and survive for long periods of time; other universes would have other characteristics, perhaps not inflating as fast and therefore collapsing before intelligent life had time to evolve. So what you have, in effect, is a selection process among all these possible universes. Only those universes that will admit life, that have just the right collection of physical constants and cosmic conditions to allow life to evolve, will have intelligent life able to ask questions like "How old is the universe?" Only in those universes where this question can be asked will it be asked. All other universes will never have intelligent life, so no such issues will ever arise.

ROBERT: The idea sounds almost trivial, a tautology--only in those universes that allow for intelligent life will there be intelligent questions. What are you adding?

FRANK: The anthropic principle asks why the universe has one value [for a given physical parameter] rather than another, since a complete range of values is possible. For example, take the cosmological constant, which results in a universal vacuum field that causes an accelerated expansion. The natural value that we theoretical physicists have computed is something like a hundred and twenty orders of magnitude larger than what is actually seen by observational astronomers. So there's a gigantic discrepancy between our theory and experiment. Now, we would expect other universes to have very different cosmological constants. But only those universes that have a cosmological constant very close to zero would be capable of giving rise to intelligent life. 

ROBERT: So the anthropic principle's notion is that there's something about our universe specially suited for intelligent life. That's not trivial. Nancey, the book you co-wrote with George Ellis, On the Moral Nature of the Universe, interrelates theology, cosmology, and ethics. Is modern cosmology compatible with traditional Judeo-Christian views?

NANCEY: That's a difficult question to answer, because cosmological theories keep changing so quickly. Those of us who specialize in the relationship between theology and science complain that since theological books get published so slowly, by the time they come out the science has often changed on you. But there are many interesting points of contact, not necessarily of agreement, that make for interesting dialogues.

ROBERT: What are some of these points of contact between theology and cosmology? 

NANCEY: Well, one of the questions has to do with the infinity of the universe. A traditional Christian claim about the universe is that somehow it must be less than God. And so theologians speak in terms of the universe being finite in time, finite in size, or at least having a contingent origin or existence. But it seems to me that if some of Andrei's theories about a universe of universes are true, then we may be looking at an ensemble of universes that is potentially infinite in time, infinite in space, and perhaps necessarily existing. And that idea begins to tread on theologians' toes. 

ROBERT: Are you uncomfortable with multiple universes?

NANCEY: If the universe turns out to be that way, Christian theologians are going to have to do some more homework to ask in what sense they can maintain those traditional claims about finiteness and contingency.

ROBERT: That's good justification for next season. Wendy, let's get back to the age of the universe, where your work has been extremely important. In recent years, astronomers faced the apparent contradiction of a universe younger than some of its stars.

WENDY: Scientists have two ways of measuring age. One is to observe the oldest stars in our own galaxy and assess their ages as determined by their masses. More massive stars burn up their fuel more quickly, and so by gauging how long a star has been burning its fuel you can estimate its age. And the estimates from the oldest stars gave us an age of about fifteen billion years. 

ROBERT: That's older than your twelve-billion-year-old universe.

WENDY: Yes, but recent measurements from a satellite called Hipparcos have revised those stellar ages down to about twelve billion years. The other way that astronomers have of measuring age is one I mentioned earlier--where we look at the expansion of the universe and extrapolate backward. To determine the age from the expansion, however, not only requires us to know how fast the universe is expanding, which is what we do with the Hubble Space Telescope, but it also depends on knowing how much matter there is in the universe, because the more matter there is, the more gravity there is, and the more the expansion is slowed down. 

ROBERT: Meaning that you can't simply run the movie in reverse, since the speed of the film today--if I've got the analogy right--may have been different from the speed in the past. 

WENDY: Right. So when we take all that into account, including estimates of the matter in the universe, we deduce an age of about twelve billion years. So now, both measurements--oldest stars and universal expansion--appear to be compatible within a margin of error.

ROBERT: And the ages are derived from independent measurements.

WENDY: Completely independent--nuclear burning in the stars and the [rate of] expansion of the universe. 

ROBERT: Andrei, let's talk some more about inflationary theory. The standard Big Bang theory has a series of intractably complex problems which inflation claimed to solve. One is the homogeneity or extremely even distribution of matter in the universe on a larger scale combined with the large clumps of matter called galaxies at a smaller scale.

ANDREI: Initially, inflation was considered as an intermediate stage of the evolution of the universe, which was necessary to solve many of these cosmological problems. At the end of inflation, as I said earlier, when the scalar field decayed, the universe became hot, and its subsequent evolution could be described by the standard Big Bang theory. Thus inflation was a part of the Big Bang theory. Gradually, however, the Big Bang theory became a part of inflation cosmology. Recent versions of inflationary theory assert that instead of being a single, expanding ball of fire, the universe looks like a huge, rapidly multiplying fractal. This fractal-like universe consists of many inflating balls that produce new balls, which in turn produce more new balls, ad infinitum. Therefore the evolution of the universe, as you mentioned in your introduction, has no end and may have had no beginning. 

ROBERT: The size scales intrinsic to inflation theory are far beyond anything ever conceived. 

ANDREI: After inflation the universe becomes divided into different exponentially large domains, inside of which properties of elementary particles and even the number of dimensions of space-time may be different. Thus, the new cosmological theory leads to a considerable modification of the standard point of new on the structure and evolution of the universe and on our own place in the world.

ROBERT: How does the size of the universe in inflationary theory help solve some of the problems of the Big Bang?

ANDREI: The total size of the observable universe--the part of the universe we see right now--can be described by the number 1028 centimeters, which is 10 followed by 28 zeros, 10 to the 28th power, a pretty huge number on the human scale. Well, the question is, Why is the universe so large? We needed a theory to explain these great dimensions. There was also another question: Why don't parallel lines intersect? At first, this seems kind of stupid--everyone knows that parallel lines do not intersect. But Einstein told us that the universe is curved, and in a curved universe parallel lines eventually may intersect. So why has no one ever seen parallel lines intersect? And there are many other questions like that, such as why different parts of the universe started to expand simultaneously, and why we see the homogeneity you referred to--that is, everywhere we look in the universe, it looks very much alike. These were the problems, and we got the answers.

ROBERT: That's why you're here; if you didn't have the answers, you wouldn't be here.

ANDREI: But these problems are kind of metaphysical. People could be excused for not even addressing them. They could say, "Well, the universe is given to us and we study it, but we don't ask questions that begin with `Why'--the universe is just the universe, and this is the way it is." Inflation theory, however, does give us a simple answer to all of these questions simultaneously. When you get the answer, you cannot forget it. 

ROBERT: We're all listening. Give us some sense of the enormity of inflation.

ANDREI: The answer is that the universe expanded extremely fast in this vacuum state. The main difference between inflation theory and the old cosmology becomes clear when you estimate what the size of the universe should be after the expansion. You get not 10 to the power of 28, which is the current size of the observable universe, but 10 to the power of one trillion--or even greater than that, depending on the model.2

{FOOTNOTE}2 The scales and orders of magnitude in inflationary theory are astonishing and they are critical to appreciate its ultimate significance. During the universe's fleetingly brief inflationary era (perhaps only 10-35 to 10-32 seconds), it is said to have increased in size by a factor of at least thirty orders of magnitude (1030) and perhaps far more. According to some inflation models reported by Linde, the universe could have expanded to 1010^12 centimeters--that's ten to the tenth to the twelfth power--to the trillionth power, a trillion orders of magnitude. It is impossible to conceive of a physical representation of this number. For comparison, the size of the observable universe containing a hundred billion galaxies is 1028 centimeters. So what kind of number is 1010^12 centimeters? Let's say you wanted to draw such a line. Assume that you had all the time needed; also assume that you could draw the line no thicker than the diameter of a hydrogen atom, and finally assume that the entire observable universe is filled with ink. Your problem is your ink: the universe of ink would run dry long before you had drawn even a tiny fraction of it. What's equally interesting, as Linde likes to explain, is that it doesn't matter what the units are--whether centimeters or kilometers or light years or even radii of the observable universe. A number this large is virtually the same irrespective of all human-devised units. Linde says that even if the universe at the beginning of inflation was as small as 10-33 centimeters, after 10-35 seconds of inflation, this domain acquires an unbelievable size. So rather than using specific units, numbers such as 1010^12 usually express the relative expansion--the increased orders of magnitude that the universe inflated. These numbers depend on the models used, but in most versions, the size is many orders of magnitude greater than that of the observable universe. {/FOOTNOTE} 
So you have this small piece of space that expands enormously. If we draw an analogy between the universe and the earth, we can appreciate the parallel-lines problem. On Earth, lines of longitude meet at the South Pole and the North Pole. Why don't we see these longitudinal lines converging? Well, it's because we live on an extremely tiny patch of the earth, far from the Poles. For the same reason, we don't see parallel lines intersect in the universe, because what we actually see of the universe is only a very small sector of the totality. 

ROBERT: Hubble has taken some remarkable pictures revealing breathtaking panoramas of galaxies, even when it's pointing at some apparently unremarkable areas of the sky. The universe seems the same no matter in which direction we look. 

ANDREI: The standard Big Bang theory has what's known as the horizon problem. That is, opposite sides of the observable universe have the same physical properties--density and temperature--to a degree of accuracy better than one part in ten thousand, even though when light decoupled from matter [about 300,000 years after the Big Bang], they were already too far apart [perhaps fifty million light-years in some models] to become homogenous. Even at this moment, they still can't communicate with each other, because they're separated by a distance very much greater than the speed of light multiplied by the age of the universe [and such communication is necessary to make densities and temperatures of different parts of the universe the same]. 

ROBERT: It's fascinating that these areas on the edge of the universe don't, in effect, know about each other's existence--whereas we do. 

ANDREI: Yes. In some sense, we're at the center of the action, but so is everything else. The real point is to explain why the right and left edges of the universe look the same. And inflationary theory does that. Just after the universe was created, in the pre-inflationary moment, all parts of the universe could see one another, so to speak, and information could pass between them. All parts of the infant universe were thus able to come to a state of equilibrium. And then inflation began, and the horizon expanded exponentially. 

ROBERT: Since the speed of inflation vastly exceeded the speed of light, after that transitory inflationary moment, it would be impossible for separate sides of the universe to ever again communicate, thus producing the situation we observe today. 

ANDREI: Indeed, we will never see some very distant parts of the universe. But it is very important to keep their existence in mind if one wants to understand his or her own place in the world.

ROBERT: So your theory asserts that everything we see--everything that Wendy [Freedman] sees with Hubble--is an infinitesimally small part of all there is?

ANDREI: Yes. 

WENDY: And the observable universe is all we have that's accessible to us, given the age of the universe and the finite speed of light.

ROBERT: Right. Most people assume that nothing can go faster than light--this is part of Einstein's special theory of relativity. But Andrei is saying that space expanded enormously faster than the speed of light, and that because there was no matter, relativity didn't apply.

ANDREI: Einstein's relativity applies to light. It does not apply to the speed of expansion of the whole thing--all spacetime. By way of analogy, suppose you send a signal along a membrane, and the signal moves at a constant speed. Next, paint two dots on the membrane. Now stretch the membrane. There is no bound on the increase in distance between these two dots if the distance between them is large, even though the signal still travels at the same speed along the membrane. Likewise, there's no bound on the speed of inflationary expansion in the early universe, even though light still travels at the same speed. Inflation theory tells how fast the whole of space expanded.

FRANK: I want to claim that if you look at the coupled equations of gravity and the Standard Model, and also throw in all the important quantum mechanics, these equations collectively have only one solution. And that solution is, the closer you get to the beginning, the more isotropic and homogenous the universe has to become. 

ROBERT: Leon, you told me you're old enough to have been there at the beginning. Do you believe in any particular theory of origin?

LEON: My high school students would say, "Gee, this is very interesting, but we weren't there and no one's ever going to be able to verify that any of this took place." So they'd ask whether there was another way to account for the creation of the world--whether there was an alternative explanation. 

FRANK: Yes. Andrei mentioned this scalar field, this vacuum field, but he neglected to mention that you have to invent it ab initio. It exists only in the theorists' minds. I prefer to use fields that people like Leon have already seen. So if you just use standard physics--that is, relativity and quantum mechanics and the Standard Model of particle physics, which involves fields we've actually observed, then there's a unique solution to how the universe began. And it began in a singularity [a point of infinite density], out of which sprang gravitation and all the other laws, energy, and matter of the universe. Now, there is an energy field--what we call a gauge field, which we're all familiar with as theoretical physicists. That's the only field we have in our normal experience. One way for you to think about it is as something like light. It's not quite light, but something resembling it.

ROBERT: And all of this gives you a solution that amounts to a single universe? 

FRANK: Yes, a unique solution, and if you--

ROBERT: And what you mean by a unique solution is that the one universe that Wendy sees is the only one there is? 

FRANK: Yes. 

ROBERT: Nancey, from a theological perspective, what is your view of inflationary theory's multiple universes versus the Big Bang's unique universe? 

NANCEY: Well, it's a disappointment to me that inflationary theory has taken off so well, because it undermines the argument that George [Ellis] and I developed in our book [On the Moral Nature of the Universe]. We started out with the anthropic principle that Frank [Tipler] talks about, and we reasoned that if there's only one universe--and we know the cosmological constant in this one--then it had to have been designed by a brilliant mathematician. And so it looked like we had grounds for a new design argument. 

ROBERT: A resurrection, as it were, of the so-called argument from design, which was one of the classical arguments for the existence of God.3

{FOOTNOTE}3 The Argument from Design, also known as the teleological argument (explaining things by their ends or purposes), is largely and long discredited. The argument is based on analogy: put simply, since a watch was created by a watchmaker, the universe was Created by a Universe-Maker. Fallacies include the nature of probability theory and the absence of external comparisons against which we can judge the putative design of the universe. Atheistic interpretations of Big Bang cosmology are represented by Quentin Smith, a philosopher of science. He states that "the thesis that the universe has an originating divine cause is logically inconsistent with all extant definitions of causality… and that these arguments, traditionally understood as arguments for the existence of God, are in fact arguments for the nonexistence of God." He asserts that since "the earliest state of the universe is not guaranteed to evolve into an animate state of the universe…[it is] inconsistent with the hypothesis that God created the earliest state of the universe, since it is true of God that if he created the earliest state of the universe, then he would have ensured that this state is animate or evolves into animate states of the universe. It is essential to the idea of God in the Judeo-Christian-Islamic tradition that if he creates a universe, he creates an animate universe, and therefore that if he creates a first state of the universe, he creates a state that is, or is guaranteed to evolve into, an animate state." Smith concludes that Big Bang cosmology necessitates that the universe "…exists non-necessarily, improbably, and causelessly. It exists for absolutely no reason at all." Smith's arguments, as one would expect, is subject to critique, such as by Christian philosopher William Lane Craig. Craig maintains that "there must be an actual cause for anything's coming to exist. In the case of creation, there was not anything physically prior to the [Big Bang] singularity. Therefore, it is impossible that the potentiality of the existence of the universe lay in itself, since it did not exist. On the theistic view, the potentiality of the universe's existence lay in the power of God to create it. On the atheistic interpretation, on the other hand, there did not even exist any potentiality for the existence of the universe. But then it seems inconceivable that the universe should come to be actual if there did not exist any potentiality for its existence… [therefore] the atheistic interpretation [of Big Bang cosmology] is less simple, has zero explanatory power, and in the end degenerates into metaphysical absurdity." See discussions of the anthropic principle that follow. {/FOOTNOTE}

NANCEY: Exactly. Other such arguments [for the existence of God] usually last for a hundred, a hundred and fifty years or so, before someone like Darwin comes along and destroys them. But it looks as though Andrei [Linde] has come along and destroyed ours in two years flat.

ANDREI: This was not my purpose. 

NANCEY: I know.

ROBERT: He had to invent new physics to do this. 

NANCEY: But he's never embarrassed about doing that. 

ROBERT: Do you have a preference? Which creation model, single-universe Big Bang or multi-universe inflation, would better support an argument from design affirming the existence of God? Or can you handle it either way?

NANCEY: It's not clear to me yet. At this point, I'll refrain from answering that question. I like the idea of experiment to decide. 

ROBERT: How do you do that?

WENDY: I think it's important to make the point that our conception of the universe has changed radically over the last four hundred years. We originally thought that the earth was the center of the cosmos, then the sun, then our Milky Way galaxy. Even in this century, we thought that the sun was at the center of the universe. We now know that the sun is one star of hundreds of billions in our Milky Way. And our galaxy is one of at least a hundred billion other galaxies. We're really at the forefront of cosmology now; we're talking about matters that haven't been subjected to the same kinds of experimental test. Some may think theory will ultimately decide. I'm for experiment. 

ROBERT: You've got to see it.

WENDY: Most people want to see it to be convinced, and in Andrei's favor there are a lot of observational data supporting inflation.

ROBERT: Inflation is an unbelievably creative solution to some very complicated problems.

LEON: It's consistent.

WENDY: It's consistent with other data we have.

LEON: I'm waiting for the Standard Model to pop out of these guys' theories. I want to see all the particles, masses, strengths, and couplings. Why are there six quarks and six leptons? Why all the rest of the stuff? Basically, some of these guys are arrogant. When I was director of Fermilab, I preached against arrogance and they took me seriously. I heard this one guy say, "Dear Lord, forgive me the sin of arrogance. And Lord, by arrogance I mean the following...." 

ROBERT: Andrei, let's go back to your scalar field. You say that inflation was energized by the potential energy intrinsic to the scalar field. Where did that potential energy come from? 

ANDREI: First of all, I should say that we did not invent the scalar field for the purposes of cosmology. Such fields and the fact that they may have energy is a necessary part of the Standard Model of electroweak interactions. Several Nobel Prizes have already been awarded for developing this theory.

ROBERT: But it's a question of initial existence, to begin with. Some theorists speak of a "quantum foam," out of which all the initial stuff of the universe--energy and matter--emerged into existence. Spontaneous eruptions, if you will, of matter and antimatter, the vast majority of which instantly annihilated right back out of existence.

ANDREI: Sure. Then the question is, Why was the scalar field in the early universe large enough to provide enough energy to create [inflate] the whole universe? Well, look at it this way. Suppose you have a small universe, just being born, but it does not contain a sufficiently large scalar field. So then--Sorry!--it dies very young [collapsing back and annihilating itself, a universal stillbirth]. Only if you have a scalar field large enough can the universe become exponentially large and enter the process of stellar production and have sufficient time to engender beings who are capable asking questions, so--

ROBERT: --the problem becomes self-solving. This leads us back to the anthropic principle, which apparently comes in two flavors, weak and strong. Frank, what's the difference?

FRANK: The weak anthropic principle is simply that the universe must be consistent with the evolution of intelligent life. The strong anthropic principle says that the universe must give rise to intelligent life at some point in its history. 

ROBERT: "Must be consistent with" versus "must give rise to"--a significant difference. The weak anthropic principle sounds like the situation Andrei was describing: only those universes that have all the conditions necessary for intelligent life will have intelligent life, and we must therefore be living in one such universe--because in all the innumerable universes that do not have these conditions, there is no intelligence around to ask or do anything.4 

{FOOTNOTE}4 The weak anthropic principle may seem obvious, which it is, and a tautology, which it is not. Assuming that one doesn't accept the strong anthropic principle--of one single universe that must give rise to intelligent life--then the weak anthropic principle seems consistent with the multi-universe idea. Because without the strong anthropic principle, reality would seem to need multiple universes to enable the self-selection of universes whereby intelligent life would exist in only those universes where intelligent life could exist. {/FOOTNOTE}

The strong anthropic principle sounds causative--that this universe was required to spawn conscious life as if by necessity. Is that what you mean? 

FRANK: Yes. 

ROBERT: Leon, does all this sound like philosophy?

LEON: That's the point. I just want to make clear that this is not physics. It's not even science in my opinion. It's philosophy. Now, many people respect philosophy--

ROBERT: But not physicists? 

LEON: Not physicists--generally, that's right. But it doesn't matter whether you respect philosophy or not. You have to make a clear distinction. This is not something that is subject to the traditional tests of science, where you propose a theory or a model, do an experiment, get data, verify [or falsify] the theory or model, predict results of future experiments, and so on. In fact, you can never prove a theory right. You can prove that maybe it's right, or you can prove that it's wrong, which is more fun. 

ROBERT: Andrei, cosmologists generally don't spend much time worrying about the anthropic principle?

ANDREI: Well, unlike many cosmologists, I like the anthropic principle very much. But there's a good reason why cosmologists generally don't like it, because some people use it without really understanding it, just to give an easy answer. If you use the anthropic principle carefully, then it's a powerful weapon, but if you use it indiscriminately then it hurts all of us. 

ROBERT: Nancey, how do you use the anthropic principle? In terms of understanding theology, that is.

NANCEY: Well, it certainly did look like good evidence that the universe had to be designed. Frank [Tipler] says that the universe had to be the way it is so that it would permit intelligent life. Then when you ask what's the basis of that "had to be," you're getting into the question of why there is a universe. 

LEON: I think there's a universe because somewhere, way back, there were the laws of physics. The laws of physics said there had to be a universe. The laws of physics were there. Now Nancey's going to ask me who put the laws of physics there.

NANCEY: Exactly. 

LEON: I'll think about it for a while. 

ROBERT: It's what we call an infinite regress--seeking causes of causes of causes ad infinitum.

ANDREI: One may ask this question in a different way. If you say that first there were laws of physics but no universe, then where were the laws of physics written? If first there was the universe without the laws of physics, then how could the universe exist without the laws of physics? And so it looks like we must have a universe together with the laws of physics. They pop up simultaneously. But who tells you that they pop up? Well, we're telling you, because we're observing. So it looks like we have three entities bound together: the laws of physics, the universe, and us. 

FRANK: I also want to remind Leon [Lederman] that living beings are a physical phenomenon and must be taken into account when you are trying to explain things. Actually, the anthropic principle has led to experimental predictions. For example, the British cosmologist Fred Hoyle realized that carbon atoms--upon which life is based--would not have significantly existed unless there was a resonance, as it's called, in a certain nuclear reaction. He predicted its energy, and experimenters found it where he predicted it to be. 

ROBERT: Wendy, is there a danger that theory can run too far ahead of hard data?

WENDY: I think that's right. It may be that ultimately, as Leon was saying, we'll have a complete theory that will explain the numbers of quarks and all other experimental data. But we may never be able to test directly whether or not there are many universes, and so we may have to rely on something like the anthropic principle, which is unsatisfying to many people. But it comes back to the fact that we're now at the forefront, asking questions that have never before been addressed by science. And while Andrei has said that there were many questions the Big Bang theory didn't answer, there are also many questions that the Big Bang theory does answer.

ROBERT: What are some questions that the Big Bang has answered?

WENDY: For example, when we look in any direction and we measure the cosmic microwave background radiation, we see that it is uniform across the sky. This uniformity of residual radiation is predicted by the Big Bang theory. There are no other explanations for the cosmic microwave background, at this point. Here's another example: when we consider the abundance of the lightest elements, like hydrogen and helium, we can predict how much would have been formed during the Big Bang. Then we can go and observe, as experimentalists, and see how much there is. 

ROBERT: How close are you?

WENDY: Very close. To within a few percent. Better. Our data confirms what's predicted by the Big Bang theory. 

LEON: That's another success, which segues into the anthropic principle. We're all charmed by these accidents [or coincidences]--for instance, if the charge of the electron were a little different from what it is, life would be, if not nonexistent, at least very different. But in our accelerator collisions, where we're trying to replicate the early universe, we make equal amounts of matter and antimatter. 

ROBERT: Antimatter being matter with the opposite charge. So if they occur together--

LEON: If they occur together, they annihilate. So, if nature makes both and prefers neither, the big question for fifty years has been, Where's the antimatter? We're here, and we're matter. We look at the solar system, no antimatter; we look at our galaxy, no antimatter. It's a mystery. What happened to the antimatter? About thirty years ago, an important experiment showed that the symmetry between matter and anti-matter isn't perfect. There's a very small deviation from symmetry, and that deviation, in combination with the Big Bang theory, means that this symmetry wasn't perfect at the beginning either and that there were slightly more quarks than antiquarks in the early universe, and that made all the difference! In a perfectly symmetric universe following the Big Bang, all matter and all antimatter would have annihilated--all would be radiation--and we wouldn't be here to speculate why--

ROBERT: But since that didn't happen--

LEON: It didn't happen because in the cooling process, to put it as simply as possible, a slight excess of quarks over antiquarks was left over--and those became us.

ROBERT: Are we living in a unique time for cosmology? The Hubble Space Telescope's pictures and data are approaching tantalizingly close to the origin of the universe. Will the next ten to fifteen years be really special, or have people always thought that their own time was special?

WENDY: I'm sure people have always thought that, but this really is a unique time in cosmology and astronomy. With Hubble above the earth's atmosphere, we can look farther back in time than we ever could before. We also have new satellites that will measure the background radiation from the Big Bang to .001 percent accuracy, which will enable us to test all of these theories again with new data--they all make predictions for this increased degree of accuracy. And besides the satellites, we also have more powerful accelerators and large ground-based telescopes linked together with advanced electronics and software. All these different technologies, never before possible, are closing in on the ultimate target. So it's not an exaggeration to say that this time is special.

ANDREI: I would compare cosmology at this time with the development of geography in pre-Columbian times. Europeans didn't know that America existed. After the New World was discovered, it was done--you had a map of the earth. So in the next ten to twenty years, perhaps we will have a map of the part of our universe that we can see--which is about twenty or so billion light years away. For billion of years into the future, irrespective of what happens to humanity, this map of the universe is not going to change. So we are participating in an event for which the universe has been waiting, in a sense, for billions of years. Just wait--another ten years or so and it will happen.

FRANK: Let's not forget that there are parts of the universe that may be forever outside our purview. 

ROBERT: Unless we engage in some other method, which Nancey might recommend.

NANCEY: Well, let's just remember that although this program was introduced as a discussion of creation, what we've really been talking about are the conditions at the very beginning, whether or how that included the laws of physics, quantum foam, scalar fields, or whatever. And that's not answering the question of creation. Why is the universe here? Why is there something rather than nothing? 

ROBERT: That, Nancey, is my favorite question [see Preface]. In a hundred years, will the multiworld interpretation--that is, many universes, all budding off from one another--be commonly accepted? 

ANDREI: Oh, yes. 

LEON: I tend to be optimistic; I will say yes, but I won't bet much on it. 

NANCEY: Let me give you a theological rationale for saying that it will be. In the fifth century, Augustine developed what he called the principle of plentitude, and that was his explanation as to why we have the sorts of beings in the world that we don't particularly like, such as mosquitoes, as well as the ones that we do, such as dogs and horses. And I think that that same principle, when you think about it, leads you to expect that there would be more universes than just the one we can observe and measure. 

ROBERT: That's an expansion of traditional theology.

NANCEY: Yes, if there is a God, and God cares about creating, then why would God stop with just this one little bubble? 

FRANK: I'll agree that there will be a general belief in many universes, simply because it's an automatic consequence of quantum mechanics. However, I don't think the inflation model that Andrei is defending will be around, because I don't think you need it to explain the universe. All you need are the standard laws of physics.

WENDY: I think many universes are quite possible. And it will be important to put this theory to experimental test, which will be difficult. But in the same way that we've moved our thinking from the sun to the galaxies to the universe, it doesn't necessarily make sense to stop with just one universe. I'd like to see experimental data, though. 

ROBERT: CONCLUDING COMMENT
REGARDING the beginning of this universe, I guess there are only three little questions: When? How? Why? It is the dawn of a new millennium and the time is good to ponder ultimate issues. We started with when, and we came up with twelve billion years ago. But I'd like to compare this number with the human life span of about a hundred years. I am fascinated by this awesome mismatch, in light of the fact that humans can envision and perhaps pinpoint the creation event, and I wonder whether it's at all related to the anthropic principle, which defines the incredibly precise universal values required for human existence. I also marvel at inflationary cosmology, which would allow for multiple universes beyond our wildest imagination, disrupting forever our attempts even to imagine the totality of existence. Are there other universes, perhaps an infinite supply, existing outside our own, with different physical laws? It's a new complication and, be assured, not a minor one. As for how, the current candidate is random fluctuations in the quantum foam, energized by the laws of physics--but where did the foam and the laws come from? Which brings us back to the anthropic principle, and the question of whether our universe was specially constructed to produce sentient life. Is that why this universe began? Sometimes only silence……………………………… gets us closer to truth.

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