Wednesday, July 4, 2007

The Universe Is Just Big Information Processor?

People are not the result of a cosmic accident, but of laws of the universe that grant our lives meaning and purpose, says physicist Paul Davies.

July 3, 2007 | Forget science fiction. If you want to hear some really crazy ideas about the universe, just listen to our leading theoretical physicists. Wish you could travel back in time? You can, according to some interpretations of quantum mechanics. Could there be an infinite number of parallel worlds? Nobel Prize-winning physicist Steven Weinberg considers this a real possibility. Even the big bang, which for decades has been the standard explanation for how the universe started, is getting a second look. Now, many cosmologists speculate that we live in a "multiverse," with big bangs exploding all over the cosmos, each creating its own bubble universe with its own laws of physics. And lucky for us, our bubble turned out to be life-friendly.

But if you really want to start an argument, ask a room full of physicists this question: Are the laws of physics fine-tuned to support life? Many scientists hate this idea -- what's often called "the anthropic principle." They suspect it's a trick to argue for a designer God. But more and more physicists point to various laws of nature that have to be calibrated just right for stars and planets to form and for life to appear. For instance, if gravity were just slightly stronger, the universe would have collapsed long before life evolved. But if gravity were a tiny bit weaker, no galaxies or stars could have formed. If the strong nuclear force had been slightly different, red giant stars would never produce the fusion needed to form heavier atoms like carbon, and the universe would be a vast, lifeless desert. Are these just happy coincidences? The late cosmologist Fred Hoyle called the universe "a put-up job." Princeton physicist Freeman Dyson has suggested that the universe, in some sense, "knew we were coming."

British-born cosmologist Paul Davies calls this cosmic fine-tuning the "Goldilocks Enigma." Like the porridge for the three bears, he says the universe is "just right" for life. Davies is an eminent physicist who's received numerous awards, including the Templeton Prize and the Faraday Prize from the Royal Society in London. His 1992 book "The Mind of God" has become a classic of popular science writing. But his new book, "The Cosmic Jackpot," will challenge even the most open-minded readers. Without ever invoking God, Davies argues for a grand cosmic plan. The universe, he believes, is filled with meaning and purpose.

What Davies proposes is truly mind-bending. Drawing on the bizarre principles of quantum mechanics, he suggests that human beings -- through the sheer act of observation -- may have helped shape the laws of physics billions of years ago. What's more, he says the universe seems to work like a giant computer. Indeed, it's possible that's exactly what it is, and we -- like Neo in "The Matrix" -- might just be living in a simulated virtual world.

Davies recently moved from Australia to set up a research institute at Arizona State University. I spoke with him about some of the controversies now raging in physics, and why he's so determined to find meaning in the cosmos.

A lot of scientists get annoyed by talk about the universe being strangely fine-tuned for life. They see this as a sneaky way to bring religion into scientific explanations for how the universe began. Clearly, you have a different perspective. Why are you so interested in the idea that the universe is just right for life?

All my career, I've been fascinated by the fact that the universe looks not just beautiful but in some sense deeply ingenious. It looks like it's been put together in a way that makes it work exceptionally well. I suppose the most striking example is that the laws of physics and the various parameters that go into those laws seem to be just right for life. If they were even slightly different, it's quite likely there would be no life, no observers, and no people like you and me having this conversation.

How many laws of physics have to be just right for life to be possible?

It's a little hard to write down the definitive list, and part of the reason is that we don't yet know what are the truly fundamental set of physical laws. Changing some of those laws by even a tiny amount would wreck the chances for life. Others seem to have a bit more flexibility. Overall, the total number of these coincidences, or special factors, is probably somewhere between a half a dozen and a dozen. I think most scientists would now agree that you couldn't change things very much and still have life.

So for all of these to happen -- for instance, for carbon to be formed, for gravity to have the precise strength that it does -- you're suggesting that it's more than coincidence that they are just right.

That's right. To just shrug this aside and say, well, if it wasn't that way, we wouldn't be here, would we? -- that's no answer to the question. It's just choosing to sweep it under the carpet. And in the case of the carbon resonance, if the strong force that binds the particles together in the nucleus were a little bit stronger or a little bit weaker, that resonance would be at the wrong energy and there would hardly be any carbon in the universe. So the fact that the underlying laws of physics seem to be just right to make abundant carbon, the essential life-giving element, cries out for an explanation.

But most scientists seem to believe it's just a lucky fluke that we're here. They say there's no inherent reason that all of these physical laws happen to have just the right properties so that carbon could form, the Earth could develop, and human beings could evolve.

You're absolutely right. Most scientists would say it's a lucky fluke. And if it hadn't happened, we wouldn't be here, so we won't bother to ask what's going on. Now, that point of view might have been tenable 20 years ago when the laws of physics were simply regarded as just there -- as God-given or existing for no reason -- and the form they had just happens to be the form they had. But with the search for the final unification of physics, there's been more of a thrust towards saying, we won't just accept the laws of physics as given. We'll ask, how did those laws come to be? Are they the ultimate set of laws? Or are they just effective at low energies or in our region of the universe?

In the past, these "why" questions -- why the laws of physics are the way they are, why the universe began, why we are here -- were questions that theologians and philosophers asked. They seemed to be beyond science. But you're saying this is an arena where science can now operate.

Yes, there was a separation of powers -- "non-overlapping magisteria," to use Stephen Jay Gould's expression. In the past, the underlying laws of the universe were regarded as simply off-limits as far as scientists were concerned. The job of the scientist was to discover what the laws were and work out their consequences, but not to ask questions like, why those laws rather than some others? But I think we've moved on since then. Are we to suppose that these laws were magically imprinted on the universe at the moment of the big bang for no particular reason and that the form they have has no explanation?

There are different versions of the anthropic principle. Can you briefly lay those out for us?

Nobody can really object to the "weak anthropic principle." It just says that the laws and conditions of the universe must be consistent with life; otherwise, we wouldn't be here. But if we combine it with the multiverse hypothesis, then we're in business. The multiverse hypothesis says that what we've been calling the universe is nothing of the kind. It's just a bubble, a little local region in a much vaster and more elaborate system called the multiverse. And the multiverse consists of lots of universes. There are different ways you can arrange this. One way is to have them scattered throughout space, and each universe would be a gigantic bubble, much bigger than the size of what we can see at the moment, but there would be many, many bubbles. And each of these bubbles would come with its own set of laws.

So the billions of galaxies in our universe still make up just one universe. But in this theory, there would be many such universes.

That's right. Everything as far as our most powerful instruments can penetrate would belong to just one universe -- this universe. I call this a "Hubble bubble." So we're talking about a distance out to nearly 14 billion light years. Everything we see within that one region of space seems to have a common set of physical laws. According to one version of the multiverse hypothesis, if you traveled enough in any direction, you'd reach the edge of that bubble, and there would be a chasm of exceedingly rapidly expanding space, and then you'd come to another bubble. And in that other bubble, maybe all electrons would be a little bit heavier or gravity would be a little bit stronger. There would be some variation. And you would find that in only a tiny, tiny fraction of those bubbles, all the conditions would be right so there can be life. And of course it's no surprise that we find ourselves living in such a life-encouraging bubble because we couldn't live in any of the others.
More at:http://www.salon.com/books/feature/2007/07/03/paul_davies/
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