INTERVIEW OF THE WEEK
STEPHEN W. HAWKING, widely regarded as the most brilliant theoretical physicist
since Einstein, known especially for his work on singularities (both black holes and the
big bang) and for his proposal of a no-boundary condition for spacetime), Lucasian
Professor of Mathematics at Cambridge University.
ALAN H. GUTH, father of inflationary big bang cosmology, V.F. Weisskopf
professor of physics at the Massachusetts Institute of Technology.
ARNO PENZIAS, 1978 co-winner of the Nobel prize for physics, co-discoverer of
the cosmic background radiation, Vice-President, Research, AT&T Bell Laboratories.
For this week’s discussion, Day Star’s president, Fred Heeren, brings together three great minds in modern physics to discuss how their discoveries relate to the order and fine-tuning of the universe. Here are the relevant portions of their interviews:
Has Hawking’s No-Boundary Proposal Left the Creator with Nothing to Do?
| Note from Fred Heeren: In his introduction to Stephen Hawking’s A Brief History of Time, Carl Sagan said that Hawking reached the tentative “conclusion” that our universe has “nothing for a Creator to do.” And he said that the book is “perhaps about the absence of God.” However, when I asked Hawking himself about this, he told me that the proposal in his book proves nothing about God’s absence, but rather, it might tell us something about His nature. |
HEEREN: Do you feel that, between inflationary models of the big bang theory and your proposal of a space-time condition without boundaries, the need for a Creator has been eliminated? What are your latest conclusions on your earlier proposal of a no boundary condition for space-time?
HAWKING:
I do not believe the no-boundary proposal proves the non-existence of God but it may
affect our ideas of the nature of God. We do not need someone to light the blue touch
paper of the universe.
This is an important distinction to be made, both for the sake of those who accuse Hawking of working to promote atheism, and for those who think Hawking’s no-boundary proposal has eliminated the need for God. Eliminating the need for a beginning, as Hawking’s statement shows, does not necessarily eliminate the need for God as the present cause of our universe. Even a universe without a beginning does not necessarily result in a universe with nothing for a Creator to do, for there may be more to running our universe than merely igniting it in a big bang.
This weak concept of God (the old deist’s concept of a God who winds up the cosmos and just lets it go on its own) would indeed be eliminated, if Hawking’s no-boundary proposal for spacetime is true. And thus Hawking can say that his proposal may affect our ideas about God’s nature. Those who believe in a personal God must agree that it is even more in God’s nature to be the ruler of the universe than to be the mere initiator of it.
In his writings, Hawking stresses that his proposal is merely a mathematical one that, as yet, has no observational evidence behind it. I also talked to Alan Guth about Hawking’s proposal.
HEEREN: What do you think of Stephen Hawking's mathematical concept of a no-boundary condition for spacetime?
GUTH:
I guess what I'd say is I think it's a very attractive picture, which is well worth
continued exploration. It suffers from the problem that it doesn't yet have a completely
well-defined theory in which to embed it. That is, it really is a notion of quantum
gravity, and so far we do not have a complete quantum theory of gravity in which to embed
this idea.
The Anthropic Principle
Whether Hawking’s idea to avoid a universal beginning is true or not, all agree that the universe we observe was either finely tuned for life at the beginning, or it is continually tuned for life now. I was keen to ask both of these scientists what they thought of the anthropic principle, the idea that conscious life is somehow responsible for this fine-tuning.
HEEREN: Much of your work is apparently aimed at finding a better explanation than the anthropic principle for the universe we observe. Why do you find the anthropic principle inadequate as an explanation for this century's findings?
HAWKING: The human race is so insignificant, I find it difficult to believe the whole universe is a necessary pre-condition for our existence. Clearly the solar system is necessary, and maybe our galaxy, but not a hundred billion other galaxies.
Indeed, the existence of billions of other galaxies strikes all of us as an extreme case of overkill, if the purpose of the universe somehow centers on us. The “intelligent design” explanation for the universe has an easy answer to this, however: As astronomers John Barrow and Joseph Silk have pointed out, the universe has to be as enormous as it is to “support even one lonely outpost of life” (because of the necessary enormity of an expanding universe by the time required for several generations of stars to cook the heavier elements, necessary for life).
Any non-intelligent anthropic explanation for the universe’s fine-tuning, however, does result in an absurdity. Hawking's reference to billions of other galaxies helps us to see the absurdity of any naturalistic system that would go to all the trouble of bringing about an entire universe of such dimensions just for the sake of a seemingly insignificant race such as ours.
Alan Guth objected to the anthropic principle on the grounds that it serves no scientific value as an explanation.
HEEREN: Why do many scientists—and correct me if I'm wrong, but apparently yourself included—try so hard to avoid the anthropic principle as an explanation for this apparent fine-tuning?
GUTH: The anthropic principle is incredibly vague. You can use the anthropic principle, if you want, to explain almost anything. And it never gives precise predictions; it only explains after the fact that what you saw was, in some sense, acceptable. So my point of view is that the anthropic explanation is always the resort of last recourse. If you can't find any intelligent theory that's compatible with what you see, that will predict what you see, then you might, as a last resort, entertain a purely anthropic explanation.
Where do scientists get their expectation for a universe that is
orderly, not arbitrary?
Whether or not one resorts to the anthropic principle, the fine-tuning problems remain. Minds at the forefront of physics today are trying to find explanations for the fact that the universe has been put together rationally, not randomly. The universe does not exhibit arbitrary patchwork, but a rational and unified framework. Thus they seek for GUT (the Grand Unification Theory) and TOE (the Theory of Everything).
HEEREN: In A Brief History of Time, one of your closing chapters is about “The Unification of Physics.” What makes so many physicists think there should be some sort of ultimate, short explanation for all the physical laws of the universe? Is it just their desire to find explanations for everything, or is there good reason to expect such an all-inclusive theory?
HAWKING: If the universe is governed by rational laws, which I believe it is, these laws shouldn't be an arbitrary patchwork, but should fit together into some unified framework.
Alan Guth’s inflationary big bang theory is popular because it succeeds in avoiding the anthropic explanation for many areas of fine tuning. Many assume that inflation has finally solved all the fine-tuning problems. Of course, I had to ask him about this.
HEEREN: Now do all these newest inflation models successfully avoid the need to invoke the anthropic principle to explain the finely-tuned laws of physics that make life possible?
GUTH: They certainly avoid several aspects that otherwise one might try to approach by the anthropic principle. As far as finely tuning things, there are still two important fine tuning problems that are not solved. One is the problem that's called the cosmological constant problem. It's basically the problem of why is the energy density of the vacuum either zero or very close to being zero. Current models of physics require fine tuning in order to make the energy of the vacuum turn out to be either zero or very, very small.
HEEREN: I see.
GUTH: And that's not understood. That's a basic problem with particle physics. The second problem is more directly related to inflation. The cosmic background radiation is uniform in temperature to about one part in a hundred thousand. In order to arrange for these nonuniformities to be as small as what we observe, we have to arrange that certain numbers that describe the underlying particle physics be very, very small, for reasons which we do not, at the present time, understand. So that's another instance of fine-tuning, which is not yet overcome by any of the theories that we have.
The fine tuning problems have become most apparent since the 1960s and 70s. But long before, the earliest pioneers of science had come to expect a universe of order, evidenced by laws that are rational, not an arbitrary patchwork, as Stephen Hawking says. I also asked Nobel prize-winning physicist Arno Penzias why this should be.
HEEREN: What do you feel makes physicists think there must be some sort of ultimate, short explanation for all the laws of nature? Is it just their desire to find explanations for everything, or is there good reason to expect a unified theory?
PENZIAS: That really goes back to the triumph, not of
Copernicus, but really the triumph of Kepler. That's because, after all, the notion of
epicycles* and so forth goes back in days when scientists were swapping opinions. All this
went along until we had a true bigot, a true believer, and this was Kepler. Kepler, after
all, was the Old Testament Christian, right? He really believed in God the Lawgiver. And
so he demanded that the same God who spoke in single words and created the universe is not
going to have a universe which has 35 epicycles in it. And he said there's got to be
something simpler and more powerful.
| * Note: Johannes Kepler sought a way to reconcile the lawgiving, orderly God of the Bible with the natural motions of the universe. Planets that moved in irregular, senseless patterns didn't fit the Bible's picture. Epicycles were proposed by the second-century astronomer Ptolemy to account for the irregularities in planetary motion, which are now accounted for by Kepler's discoveries that the planets orbit the sun in an ellipse with the sun at one of the two foci. To Ptolemy, however, each planet appeared to move in an epicycle, a circle whose center moves around the circumference of a larger circle. |
PENZIAS: Now he was lucky or maybe there was something deeper, but Kepler's faith was rewarded with his laws of nature. And so from that day on, it's been an awful struggle, but over long centuries, we find that very simple laws of nature actually do apply. And so that expectation is still with scientists. And it comes essentially from Kepler, and Kepler got it out of his belief in the Bible, as far as I can tell. This passionate belief turned out to be right. And he gave us his laws of motion, the first real laws of nature we ever had. And so nature turned out to redeem the expectations he had based on his faith. And scientists have adopted Kepler's faith, without the cause.
You'll find the whole history of these twentieth century cosmological discoveries, and the bigger implications for everyday life, in Day Star's new book, Show Me God.
DAY STAR’S DISCUSSION KICKER OF THE WEEK:
You’ve just heard three of today’s top physicists talk about our expectation of
an orderly, not an arbitrary, universe. Day Star’s book, Show Me God, gives a number of
different explanations for this order. What’s your best explanation for why our
universe should be set up this way? Do you believe that Kepler’s (and the
Bible’s) early expectation for this sort of order was a coincidence, or do you think
it may have been based on something deeper?