Posted on 09/09/2001 1:05:44 PM PDT by telos
A GROUP of astronomers and cosmologists has warned that the laws thought to govern the universe, including Albert Einstein's theory of relativity, must be rewritten. The group, which includes Professor Stephen Hawking and Sir Martin Rees, the astronomer royal, say such laws may only work for our universe but not in others that are now also thought to exist. "It is becoming increasingly likely that the rules we had thought were fundamental through time and space are actually just bylaws for our bit of it," said Rees, whose new book, Our Cosmic Habitat, is published next month. "Creation is emerging as even stranger than we thought." Among the ideas facing revision is Einstein's belief that the speed of light must always be the same - 186,000 miles a second in a vacuum. There is growing evidence that light moved much faster during the early stages of our universe. Rees, Hawking and others are so concerned at the impact of such ideas that they recently organised a private conference in Cambridge for more than 30 leading cosmologists. Cosmology - the study of the origins and future of our universe - became popular in the early 20th century for physicists who wanted to think the unthinkable about creation. Einstein's theory of relativity, which describes how gravity controls the behaviour of our universe, was one of cosmology's greatest triumphs. But Einstein said there was an even deeper issue, which he described as whether God had any choice. In other words, could the laws that governed the way our universe formed after the big bang have worked any differently? He concluded that they could not. In the past 40 years, however, the increasing power of astronomical instruments has turned cosmology from a theoretical science into a practical one and forced scientists to re-examine Einstein's conclusions. Among the most striking claims is that our universe only exists because of a fine balance between several crucial factors. One is the rate at which nuclear fusion releases energy in stars such as the sun by squashing hydrogen atoms into helium and then other elements. Astronomers have found that exactly 0.7% of the mass of the hydrogen is converted into starlight and that if this figure had been just a fraction different then carbon and other elements essential to life could never have formed. Another puzzle is the so-called "smoothness" of our universe, by which astronomers mean the distribution of matter and radiation. In theory, the big bang could have produced a universe where all the matter clumped together into a few black holes, or another in which it was spread out evenly, forming nothing but a thin vapour. "It could be that the laws that govern our universe are unchangeable but it is a remarkable coincidence that these laws are also exactly what is needed to produce life," said Rees. "It seems too good to be true." What he, Hawking and others such as Neil Turok, professor of maths and physics at Cambridge, are now looking at is the idea that our universe is just one of an infinite number of universes, with different laws of nature operating in each. Some universes would have all their matter clumped together into a few huge black holes while others would be nothing more than a thin uniform freezing gas. However, Hawking and his colleagues increasingly disagree over how this "multiverse" could work. At the conference Hawking dismissed the idea of a series of big bangs on the grounds that it extended into the infinite past and so could never have a beginning.
Did photons appear during or before the inflationary period? If they did appear, could they go anywhere without being absorbed by some kind of intergalactic gas [before the stars and galaxies appeared]?
God's honest truth? I can't help you here. While I understand Guth's contention that inflation proceeds faster than light, causing different portions of the universe to lose causal contact with each other, it is not exactly clear to me why it doesn't run afoul of special relativity. I think I can regurgitate the causality argument that permits it, but the math has eluded me.
Here's another misunderstanding I have about inflation. It's rather technical and I hesitate to mention it here, but I can't resist the opportunity to drop names, because I actually asked this question to a panel consisting of Guth, Michael Turner, Paul Steinhardt and Burt Ovrut, the giants of inflationary cosmology. Other cosmology giants such as Max Tegmark and Miriam Cvetic were there to speak up if they misspoke. (I was even sitting next to Alan Guth's mom at the time; although I didn't expect her to contribute to the discussion, some mojo might have rubbed off.)
We know that the total energy of the universe is zero. The problem is that mass, as well as energy, is conserved. (Suppose, for example, I have a pi0 of 135 MeV that decays into two photons of 67.5 MeV. The photons are massless by themselves, but together they still represent an invariant mass of 135 MeV.) But while there is negative energy (gravitational fields) there is no such thing as negative mass. I can't meaningfully discuss "the mass of the universe" as a concept, but I can state with confidence that there exists at least 100 kilograms of mass in the universe, because that is my mass. So since the universe started out with less than the amount of energy this represents, where did all my mass come from?
The answer was that it comes directly from the collapse of the false vacuum, and that mass conservation itself is only an effective global symmetry anyway. That's probably the correct answer, but again, the math eludes me.
Good question. Photons per se didn't appear until the breaking of the electroweak symmetry, which was right about at the end of the inflationary epoch. But still there were some sorts of massless gauge bosons flitting around the universe all through inflation, that can serve as conceptual stand-ins for the photons we see nowadays (but that didn't technically exist back then).
So you're saying that God couldn't have made it that way if he wanted to. OK, I believe that you believe it.
Like a space plateform that rises from earth's surface, using some of horizontal propulsion to achieve orbit. Or an anti-gravity sled that can carry huge amounts of spoil from an excavation site to a dump site. Or overcoming limitations of vertical construction. In fact, there probably many, mnay more uses for such an application than I could even think of.
Get busy, young Einstein. The world needs you.
Wow.
Congratulations PH, looks like you managed to "stump the band!"
Anybody know what the prize is for getting "Physicist" to cry "Uncle!"? An fun-filled one week, all-expense paid vacation with medved and G3K?
All kidding aside, thanks for sharing your uncertainty on this topic; I was merely regurgitating what I thought I had read previously. And I certainly haven't even looked at the math behind it.
Perhaps one of our other resident cosmo-nerds can shed some light (no pun intended) on this topic.
I'm sure it's no comfort, but the math eludes me too. And all that Higgs-field stuff which starts the whole inflationary scenario going. But I shall persever in my reading. At this point, I gather that inflation solves a whole bunch of problems (monopoles, smoothness, etc, which I never knew were problems) but it still has a gerry-rigged feel to it. For what that's worth.
I'm just speculating now, so bear with me. Is it possible that something about the inflationary scenario leads to the equivalent of a "temporary suspension" of the law of Conservation of Matter, which resumes it usual role and authority once the inflation phase is complete?
In the alternative, are you saying that the matter formed in the inflationary phase does NOT violate the C of M?
You tell me.
Oh, that's the one thing it doesn't have for me. There are no epicycles here, you start with one very simple concept--the false vacuum--and the rest just sort of unfolds uniquely out of it. It's like the way the Mandelbrot set just unfolds out of Z<--Z² + C. That's not to say that I personally understand all the details of how it unfolds, but there often comes a time when we dumb experimentalists have to take a theorists word for it.
And He did, too. But His book is written on the face of the sky, and not on the face of a page. I assure you He was quite clear about the expansion of the universe, in the book that counts.
U.S. Has Heavily Researched Anti-Gravity, Book Says
Not that I think there is anything to this doesn't stop me from reading up.
I have trouble unfolding a camp-chair!
Good metaphor...do you think there is any significant isomorpism between them?
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