April 19, 2007 at 11:25 PM ET
Why does the universe seem so fine-tuned for the emergence of life – including intelligent life capable of asking that “why” question? Believers simply say that God did it, while scientists are trying to come up with complicated extradimensional multiverse theories to explain our lucky break.
Theoretical physicist Paul Davies takes a completely different tack in a new book titled "Cosmic Jackpot." He argues that the cosmos has made itself the way it is, stretching backward in time to the very beginning to focus in on “bio-friendliness.”
|Paul Davies heads up the |
Beyond Center for
Fundamental Concepts in
Science at Arizona State
Davies admits that the idea has theological overtones - but that's nothing new for the London-born deep-thinker. He's perhaps best-known for provocative books such as "The Mind of God" and "God and the New Physics," and for holding forth on speculative topics such as whether physical constants are actually inconstant.
After years of teaching at universities in Britain and Australia, Davies moved to Arizona just last year to start up Beyond, a research center devoted to fundamental scientific questions: How did the universe begin? How did life arise? Where do humans fit into the grand scheme? What does it all mean?
"We've been up and running for only about three months, so it’s early days," he told me Wednesday. "But we have high hopes that this will become one of the world’s leading think tanks for confronting these foundational questions."
He's currently on a cross-country tour to promote the book; on Wednesday, he lectured at George Mason University near Washington, D.C., and tonight he's giving a talk in "the other Washington," at Town Hall Seattle (and I'm planning to see him there). During a half-hour telephone interview, Davies touched upon his key theme of the universe's curious bio-friendliness. Here are excerpts from the conversation:
Cosmic Log: Why is the universe bio-friendly? Is it intelligent design, or blind chance, or none of the above?
Davies: There are three popular responses to the fact that the universe does seem to be weirdly fine-tuned for life. And I think all three are found wanting.
The three are the intelligent-design argument; the idea that if we had a final theory of physics, then all of the undetermined parameters in the laws would be fixed by that theory; and the third is the multiverse – the notion that there is a multiplicity of universes, with laws that vary from one to the other.
I think all three of these explanations are found wanting – and I have my own preferred view, which is that the universe has engineering its own bio-friendliness through a sort of feedback loop that operates in both directions in time.
Q: You’ve noted that some experiments have already been conducted – John Wheeler’s experiment in backward causality, for example. And there’s another experiment that the University of Washington’s John Cramer has been hoping to conduct, although he doesn’t seem to have the money to do that quite yet. Are those the sorts of experiments that can shed light on the type of phenomenon you’re talking about?
A: Yes, there are many examples of what you call backward causation. You have to be very careful about the use of that term, because the sort of experiments that I discuss in the book can’t be used to send information back in time. The essence of quantum physics is Heisenberg’s Uncertainty Principle. This operates in both directions in time to prepare a state now. The situation in the future is uncertain, but the situation in the past was uncertain, too.
In the conventional way of conducting a quantum experiment, you prepare an initial state and you make some sort of measurement on it as it relates to time. But in the case of applying quantum physics to the universe as a whole, that’s not really an appropriate way to look at it – because we don’t know what the initial state of the universe was, and we certainly can’t prepare it. We make observations now, and we infer things about the past.
The best way of thinking of this is that in quantum mechanics, many different possibilities combine together to form an amalgam, and the present state of the universe is made up of all of the possible past histories that amalgamate together, to give us what we observe. So if we think of the universe as this multiplicity of histories, we must obviously restrict ourselves only to those histories that give rise to life and observers, because that’s the universe that we’re in.
In essence, what happens when we make measurements or observations of the universe today, we’re resolving some of the quantum ambiguity that exists in the past, as part and parcel of quantum uncertainty. Stephen Hawking has made this very explicit just in the last few months in a paper published with Thomas Hertog, in which he says that the way to apply quantum mechanics to the universe as a whole is to project backwards in time from our present observations. This brings in the role of the observer in a very fundamental way.
So although it looks like this is being couched in the language of backward causation – that what is happening now is somehow affecting the past – it’s entirely in accordance with our understanding of quantum mechanics. There’s nothing new that’s being included here. Einstein expressed it very well: He said quantum mechanics is a form of ghostly action at a distance. Well, action at a distance can be action through time as well. The one goes with the other. This action goes both forward in time and backward in time. Quantum mechanics naturally links past and future, and different points in space.
Once you’ve got that linkage, you have the basis for the universe being able to engineer its own bio-friendliness through this sort of quantum feedback.
Q: We should probably spend a little more time on that idea, and the popular notion that this opens the way for backward time travel – the paradox that says you could go back and kill your grandfather before your father was born. Such ideas may hint at the scientific reality, and make for a great movie, but might not completely reflect the truth.
A: We’re not talking about time travel here. We’re not talking about changing the past, or sending information back into the past. We’re talking about merely using the existing quantum ambiguity. When we make observations, we in part resolve some of the ambiguities that are inherent in the system.
I’ll give you an example: You prepare an atom in a particular state, moving in a certain way perhaps, and quantum mechanics tells you that at a later time that atom can have a variety of behaviors. When we make observations at that later time, you find one particular behavior. You’ve resolved that ambiguity that was inherent in the initial quantum state. But this goes back in time as well, and when we make observations today, they can resolve ambiguities about the past.
In that manner, what we must imagine is that the origin of the universe is an amalgam of realities, and only those realities that lead to observers who can resolve those ambiguities are going to be selected for. So the universe can engineer its own bio-friendliness, because the very observers who arise at a later stage are those who project out from the bio-friendly histories. The universe explains observers, and observers explain the universe.
Although this sounds very radical, it’s a very old idea. It goes back at least 30 years to the work of John Wheeler. A number of other well-known physicists – including Hawking, and Murray Gell-Mann and Jim Hartle – have suggested something similar. I’m here at George Mason University with Yakir Aharonov, who is also suggesting something similar. He calls it the destiny wave function from the future.
These are just ways of reformulating standard quantum mechanics to bring out in a dramatic way the fact that you can’t chop time up into slices and expect them not to be connected. What’s happening now links back to the past just as it links to the future. And in quantum mechanics, there’s always such a clever mechanism that there is no way of using this to send information back in time or change the past.
Q: Right, and you’re not talking about some super-intelligent being who is able to engineer the past by going backward.
A: Some people have suggested that. They have suggested that cosmic bio-friendliess is precisely due to some super-intelligence that went back in time and fixed up their own power, or something like that. Or that a super-intelligence in another universe created this universe with bio-friendly parameters. All of those things have been tried – all wildly conjectural, of course. But what I find lacking in all of those theories, including the more conventional intelligent-design argument, is that they appeal to something outside the universe that has to be accepted as given and cannot be proved. I’d like to try to explain as much of the universe, including its bio-friendly laws of physics, from within the universe – and in a way that doesn’t appeal to something outside of it.
Even standard physics says the laws of physics are friendly for no reason, but have just been imprinted upon the universe at the time of the big bang from without, by some unknown mechanism. Again, the argument makes an appeal to something outside the universe, instead of something intrinsic to it.
Q: In the book you mentioned that Hawking’s scenario calls for the origin of the universe to be fuzzy in a quantum way. There’s not necessarily some sort of “hard start” for the universe.
A: Right. Once you apply quantum mechanics to the universe as a whole, everything becomes fuzzy. But I want to go beyond ordinary quantum fuzziness, which I think needs an additional step, and introduce fuzziness into the laws themselves.
Most people think that although you have many quantum histories, you’ve got the same underlying physical laws. But I argue in the book that we should abandon the notion of fixed, fundamental laws and instead advance the notion that the laws themselves have a fuzziness or ambiguity. We can still appeal to this feedback mechanism that we and others – Cramer as well – have introduced from quantum mechanics, but extend it to the laws as well as the states of the universe. So that’s the radical step: the idea that there are fuzzy laws as well as fuzzy states.
Q: And as physicists observe the operation of those laws, there is some decoherence going on? And that’s what makes the laws seem to be firmly set laws?
A: Well, I wouldn’t use the term “decoherence” because that has a specific connotation, connected with the quantum superposition. It is that there is an inherent fuzziness in the very mathematical nature of the laws, which is time-dependent.
If I can back up and tell you where all this comes from, the traditional notion of the laws of physics is that these are absolute, universal, immutable, mathematical relationships existing in some Platonic realm which transcends the physical universe, in some realm of mathematical forms. The orthodox interpretation of the laws is that are these infinitely precise external entities. But increasing numbers of theoretical physicists have an entirely different take on the nature of the laws of physics, which is that they are more like software being run on the great quantum computer called the universe.
So we think of the universe as an information-processing system, a gigantic computer, and the laws of physics are simply the algorithm that is being run.
Q: And we all know that the answer to the ultimate question is 42.
A: Right, heh. Anyone who’s got a computer knows that all real computers are limited in resources and processing speed, and the universe is no exception. We can work out the information-processing capacity of the universe. It’s finite – and it comes out with a very big number, about 10122. That number is so big that for almost all practical purposes, it makes no difference whether we think of Mother Nature commandeering this finite-resourced computer, or whether Mother Nature computes in the Platonic heaven with infinite precision.
There are certain senses in which there is a difference – including senses we can experiment with in the lab right now. But the significant thing is that in the past, the number was much smaller. When you go back to the time when the structure of the universe was being laid down – the time of inflation, 10-34 seconds, the bits that the universe would have contained was only about 1020. So if we restrict our description of the laws of physics to have that accuracy – one part in 1020 – then that starts to become significant.
NASA / WMAP
|A sky map from the Wilkinson Microwave Anisotropy |
Probe shows minute variations in temperature that
were caused by "ripples" in the early universe.
The image that we have of the laws of physics is that at the beginning, they are completely fuzzy and indeterminate and unfocused. Then, as the universe expands and its information capacity rises, the laws become meaningfully focused. It simply has no meaning to apply laws of physics to more precision than the entire universe itself could actually compute to. In this view, the laws focus in from this “higgledy-piggledy origin,” as John Wheeler says.
Then the issue we are confronted with is, why do the laws focus in on this bio-friendly set? That’s where we get this feedback loop. Once you concede that the laws themselves has this wiggle room, because of the finite capacity of the universe, then the way lies open for the universe to engineer these bio-friendly parameters through this feedback loop.
Q: One of the issues you’ve been looking at over the years is the intersection of science and religion. Do you find that these new ideas – about the cosmic landscape, for example, or the quantum nature of the universe – are informing religious or spiritual thought as well?
A: Well, they clearly impacted greatly, because we’re talking about why the universe looks like it’s been fixed up for habitation. For most people, the first interpretation is, “Well, God did it.” What I’m saying is that that gets us nowhere at all. It just shoves the problem off to some other realm. But saying “God did it” is no worse than saying “the laws of physics did it.” They both basically appeal to something outside the universe.
The problem with saying God did it is that God himself or herself is unexplained, so you’re appealing to an unexplained designer. It doesn’t actually explain anything; it just shoves the problem off. But to say that the laws of physics just happen to permit life is no explanation either.
What I’m trying to do is to go beyond this rather sterile back-and-forth between religion and science on these ultimate questions. We’re trying to come up with a new set of ideas, in which we try to let the universe engineer its own bio-friendliness. So we try to find the explanation from within the universe. Now, that’s perfectly consistent with having a universe that has some sort of deeper meaning or purpose, but that meaning or purpose is intrinsic to it. It’s not imposed upon it by an external deity. So these ideas obviously have theological implications.
For more about the big questions in cosmology, check out our "Beyond the Big Bang" online tutorial. And feel free to add your own comments – but this time, please refrain from taking shots at the comments of others.