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Falsification of eternal inflation 
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#1
Mar1711, 04:29 AM

P: 21

Almost all planets in a multiverse with eternal inflation will be much younger than our earth.
Almost all conscious creatures in such a multiverse will live on young planets with an exceptionally quick evolution (related to the theoretical expected evolution speed). But we live on an old planet with an evolution that most biologists don't think is exceptionally quick. I think the observation of our situation and this reasoning is a falsification of eternal inflation. Why do people believe in eternal inflation anyway? 


#2
Mar1711, 05:51 AM

P: 450

If you would like to understand the case for eternal inflation. Guth states it here:
http://arxiv.org/abs/hepth/0702178 


#3
Mar1711, 06:11 AM

P: 21

I've read that.
Eternal inflation predicts that almost all conscious creatures live on planets with close to maximal evolution speed. That would mean that our earth is extremely atypical, it doesn't make sense. 


#4
Mar1711, 07:18 AM

P: 450

Falsification of eternal inflation
I dont think cacluating probabilites in the multiverse is as clear as youve suggested.



#5
Mar1711, 08:15 AM

P: 21

I think it's clear and easy. If it's not I wish someone can explain why.



#6
Mar1711, 02:47 PM

P: 688

I have worked through some of the math of choatic eternal inflation. It has its merits but there is quite a bit of hand waving and in the end I was not convinced I did a scientific calculation.
I would ask: is eternal inflation really needed to explain any observations? 


#7
Mar1811, 05:20 AM

Sci Advisor
P: 4,782

It turns out that our existence in boxes 110 provides no evidence whatsoever one way or the other as to which of these theories is more accurate. 


#8
Mar1811, 05:36 AM

P: 21

Chalnoth,
I think you missed my argument, I'm afraid I didn't explain it very well. Let's say we have a theory that says that one box is filled with blue color, and 99 boxes are filled with red color. Another theory says that 99 boxes are filled with blue color and one box is filled with red color. That's more like my argument. I think if we open a box with blue color we know which theory is the more probable. Eternal inflation predicts that we find ourselves in a world with a very fast evolution. That's not what we see and from my point of view it makes eternal inflation an impossible theory. Eternal inflation predicts red but we find blue. I'd be very happy if someone can understand my argument. 


#9
Mar1811, 05:41 AM

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#10
Mar1811, 06:37 AM

P: 21

Chalnoth,
You have no reason to be certain that this line of reasoning doesn't work, but you are right that I didn't define the problem very well. Anyway, now I read Guths paper, it's a great one, and realize that this problem is very much about the youngness paradox. Guth believe that his reasoing about the youngness paradox is fine, but he admits: "Although the problem of deﬁning probabilities in eternally inﬂating universe has not been solved" So this is an open question I guess. Then I would like to state the following: If the youngess paradox is true, then eternal inflation is false, because we have no reason to believe we are that special from a biological perspective. What do you think of that statement? 


#11
Mar1811, 07:31 AM

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#12
Mar1811, 07:32 AM

P: 751




#13
Mar1811, 07:42 AM

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P: 4,782

Eternal inflation continues causing part of the universe to expand at a dizzying pace forever into the future. Every second, an everincreasing number of regions begin reheating. Because the number of new regions increases into the future, an equaltime slicing at any point of the universe will be overwhelmingly dominated by newlyreheated regions. I forget the exact numbers, but it's something like there is roughly 10^90 times more volume in regions that are just one second younger (this is because inflation causes the universe to grow by about 10^90 in volume every second). By this estimate, you would have around 10^(2,840,123,340) times as much volume in regions of the universe one year younger than our own (yes, that's a 1 with nearly 3 billion zeros following it). The probability estimate, in other words, depends critically upon this idea of taking an equaltime slicing of the universe. Which I claim is nonsensical: whatever is going on outside our region of our visible universe cannot have any impact on anything that is going on here. 


#14
Mar1811, 07:58 AM

P: 751

It's a problem in specifying asymptotic frequencies in infinite sets. If you write down the natural numbers (in base 10) according to a certain pattern, you will always have more numbers starting with the digit 1 than with any other digit. So you could "prove" that, asymptotically, most numbers start with the digit 1. But it's just an artefact of a particular ordering. There must be a sensible mathematical or logical approach to such problems, but I don't know what it is.



#15
Mar1911, 11:59 AM

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P: 9,372

I was under the impression eternal inflation implies the 'multiverse' is undefinably ancient. Under that premise, it appears the universe in which we reside has an indefinite lineage of prior universes  hence we are among the younger of all universes having ever existed.



#16
Mar1911, 12:26 PM

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#17
Mar1911, 12:56 PM

P: 21

Mitchell porter,
I think if we are dealing with infinite sets I guess you're right it's hard to do the calculations (I didn't try ). However, personally I don't grasp the concept of actual infinites in the real world. Am I supposed to believe in that? Eternal inflation has a beginning and I don't see how it reach infinity somewhere. I guess my assumption is that we don't deal with an infinite set. Chalnoth, You're right that what's going on outside our region doesn't impact us. But we don't know what's going on there, we just have a theory and a theory must make predictions. It appears that we know that at any time the number of young universes are so many more than the old ones, it simply looks like we can use that knowledge. Maybe it's nonsensical, and if you're thinkning of infinites like Mitchell, then I guess our different intuitions have to do with that. (Maybe your philosophy of time is eternalism but I go with presentism) 


#18
Mar1911, 01:06 PM

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