eh

Hawkings argued that inflation can't work, but that was back in the early 80's. He changed his mind after a debate with Guth, and now appears to be a supporter of the theory. That also seems to be the case with most cosmologists, though we all know how things can change.

Bill

Unless I misunderstand, the entropy of a totally empty system (a "quantum vacuum") would be at the maximum possible value (but less than "infinite," due to quantum uncertainty, which operates to make the "totally empty system" somewhat less than "totally empty").

Entropy is at its minimum value at the instant of the "Big Bang."

== Bill

Answerer

Well, it seem to me that Guth is trying to prove the credibility of the bible itself. This, in turn, makes me wonder that why does he still have to look for the 'beginning' when he have so much faith in the bible's fairy tales?

eh

What in the world are you talking about, Answerer?

BTW, it was a debate in Moscow with Linde that I was refering to, not with Guth.

Steven S

This looks to me like pure speculation. I'm not sure why these guys recieved all the media attention that they have.

Steven S

Synaesthesia

Bill,
The god hypothesis resolves the issue slightly less satisfactorily than naturalistic explanations- generally the best place to stop an infinite regress is before it begins. So if our intention is to avoid regression, it's more parsimonious to end it at the universe itself and say that external "causation" is meaningless. There was no time, after all, at which the universe did not exist.

God does not resolve the problem, and creates others. For those without prior commitment to a deity, there is simply no reason to invoke such a hypothesis here.

Bill

First, the media likes stories of scientific controversy. Witness all of the coverage for anything about "cold fusion," etc. etc. etc.

Second, I think it is wrong to characterize this as "pure speculation" from merely examing the CNN article. When I look at <a href="http://feynman.princeton.edu/~steinh/" target="_blank">Steinhardt's own home page</a>, I see the expected collection of preprints of his actual papers to back up these assertions. The layman's introduction begins with these words: Now, I don't need to explain that inflation theory has been controversial from the beginning. It gained acceptance largely due to the "no other successful approach" situation. Nobody could figure out another way to get the job done.

Also, the whole business of the "Big Bang" creating an entire space/time continuum has also been quite controversial (to the point where I would not even call it "broadly accepted"). Two years ago, our own Richard Carrier published his essay <a href="http://www.infidels.org/library/modern/richard_carrier/bigbang.html" target="_blank">Was There a Big Bang? I Honestly Don't Know (2001), 2nd ed.</a>, which begins with these words: Yes, very few facts; but no, more than "pure speculation."

The idea of the cyclic universe has been floated before. Steinhardt, et al., engage in large amounts of self-puffery when they claim that "The Cyclic Model is a radical, new cosmological scenario..." Yes, perhaps their particular Cyclic Model is radical and/or new, but we've clearly heard these words before. And it is obvious in the idea that they didn't need to reach for a new vocabulary. They just dusted off the old reliable "Big Crunch" to describe their version of what happens when their version of the model of the universe stops expanding and begins contracts back into a small highly-explosive spot once again.

Anyway, I've run my eye through <a href="http://feynman.princeton.edu/~steinh/dm6.pdf" target="_blank">the introductory material</a> and I'm personally gratified that they are having their ideas promoted in the mass media this way. I think it will do cosmology some good to resurrect an old controversy and allow the scientists to look for some testable hypothesis that will discern which of the models is closer to being the correct model of "the way things really are." As things sat for the past decade or so, there was no serious attack on the "Big Bang" model, in spite of numerous disturbing developments (such as "dark energy").

It will be interesting to watch this one play out. Ultimately, though, I figure that this approach will win or lose based upon whether or not anything comes out of M-Theory, from which this new cosmological model takes its inspiration.

== Bill

Steven S

Alright, I'll grant it the status of "very speculative" rather than "pure speculation". When I first read the CNN article I thought, 'so what? if he can't distinguish this from other cosmological models it is useless' but in his paper he claims that the future gravitational interferometry experiments could distinguish it from inflation.

Steven S

eh

Those gravitational tests, should be done in 2003. So by then, we will at least have some evidence either way for this theory. It's going to be a good century for cosmology.

Answerer

BTW, it was a debate in Moscow with Linde that I was refering to, not with Guth.[/QB][/QUOTE]

Oh, don't misunderstood my intention, I'm not talking about your reference of the debate in Moscow.

[ April 29, 2002: Message edited by: Answerer ]</p>