Good news about the Big Bang
post by xamdam · 2010-11-25T12:44:45.663Z · LW · GW · Legacy · 3 comments(Disclaimer: very poor knowledge of physics here, just interpreting the article)
http://www.physorg.com/print209708826.html
- looks like there are many of them, as non-creationists would expect
The really good news is
> In the past, Penrose has investigated cyclic cosmology models because he has noticed another shortcoming of the much more widely accepted inflationary theory: it cannot explain why there was such low entropy at the beginning of the universe. The low entropy state (or high degree of order) was essential for making complex matter possible.
Which I interpret to mean information passes through the Big Crunch/Big Bang cycle. No heat death, information passes through - good news for transhumanists?
3 comments
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comment by JoshuaZ · 2010-11-25T15:01:25.516Z · LW(p) · GW(p)
I'm skeptical of this claim. It seems that the body of evidence now suggests that this universe is not going to undergo a Big Crunch, which means that if there had been previous cycles, this is the last one. This seems very unlikely. I'd put very little credence therefore in this sort of claim until we see how it fits with other data and models.
Moreover, this shouldn't make transhumanists that happy. Even if this has occurred in the past, there's likely a limit to how much information must have been transferable into useful forms given that we don't see evidence of any entities from the last cycle.
comment by Manfred · 2010-11-25T15:01:27.785Z · LW(p) · GW(p)
Interesting.
I wonder about the statistical fitness, though. The evidence appears to suffer from two problems: multiple tests and difficulty of assessing counterfactuals.
The whole proof that we should expect "more average" rings in the paper was quite handwavey, and there are some associated flaws. If we discovered rings of hotter material, would that also be evidence? If they did search for other structures, we should discount for multiple tests.
The real statistics problem is how unlikely this actually is if the universe is inflationary. They quote "6 s.d.," but that was arrived at fairly unsatisfactorily - the model they compare to is not an actual inflationary model, which is what they should be comparing again. Perhaps they could try finding low-variance squares or triangles in the data :D
A more specific, sciencey problem is that for the smaller low-variance circles you'd expect it to be really easy to spot a temperature deviation as he predicts. Yet in the one example he shows, it looks normal. Also, depending on the specifics of this cosmology he's supporting, energy bursts with times of origin after the big bang may be a problem.
comment by [deleted] · 2010-11-25T16:08:48.594Z · LW(p) · GW(p)
As I understand it, Penrose's CCC posits that the universe will become "space-like" in the far future because all matter will be absorbed by black holes and eventually re-emitted as photons; thus it will be impossible even in theory to build any kind of clock after this occurs. (This also means total information entropy.)
(This summary comes from my probably flawed understanding of Penrose's description of CCC in the book On Space and Time.)