Cosmology Question

[JayTee]

Note: I may be completely misunderstanding this topic.


In Richard Dawkin's book, The God Delusion, he discusses the anthropic principle and how it relates to the existence of life. A supporting argument from some theists is the fact that the laws that govern the universe would not support life if they were different (one example being the strong nuclear force.)

Now, obviously if they were different we wouldn't be here to discuss it. When discussing the existence of life on Earth as being an improbable occurrence we have to consider the fact that there are billions of galaxies containg billions of stars that could possibly contain a planet hospitable to life. Since we only observe one universe then this argument doesn't apply.

An argument is put forth other than that of the multiverse, which is that the big bang is followed by a big crunch. This apparently might allow the constants to reset themselves and give multiple oppurtunites to achieve a set that is hospitable to life.

Here's my question:

First off, is this accepted as a possibility by the scientific community? (I wouldn't imagine that Dawkin's would discuss it if it was bunk.)

Secondly, do these constants determine if the universe eventually contracts after the big bang, constantly expands, or eventually becomes static? If so, wouldn't these constants eventually attain a value leading to constant expansion or the eventual becoming static of the universe, thereby ending the big bang - big crunch cycle?

[vhawk01]

Another theory that he puts forward that I particularly enjoy, although I am the first to admit it is entirely random speculation and has no evidence to support it, is the idea that universes give 'birth' to other universes through black holes or some other mechanism, and that there is something about the universes that are amenable to life that are ALSO amenable to spawning these other, daughter universes. Its similar to why we see things that prefer to stay alive. There is nothing special about things that want to live, its just that the things that dont want to live aren't around anymore. There is nothing special about universes that like to form black holes and are amenable to life, its just that the ones that aren't don't make more universes and so quickly die out.

Like I said, completely unsupported but it has some aesthetic quality, I think.

[arahant]

I think most cosmologists are pretty comfortable invoking the anthropic principle.

When you first start to think about it, it sounds a little odd and circular (which is kind of the point, i guess), but I think it is pretty strong.

Part of the problem is that it's really not an 'explanation' in the classic sense. It's not a causal argument based on other principles, but rather stands alone. I personally think of it as less of an explanation, than simply 'the way things are' (that may not make sense).

It's not required that there be multiple universes, or that constants can reset themselves, because it's entirely conceivable that life might just never form, anywhere, anytime, in any universe. In other words, there could be exactly one universe, that just happened to support life without weakening the anthropic principle.

Tomorrow, I'll read up on others' thoughts and try and give a better answer. In particular, I'm not entirely sure off the top of my head which constants are required for life. There are probably ranges in some that would still allow self-replication, and the ultimate development of complex life.

As to the ultimate state of the universe, the constants that people generally think of as required for life don't (within the ranges under dispute) demand a collapsing or expanding universe.

Interesting question, which I've never looked at in detail. I've always taken it as obvious (which in some sense, it is).

[JayTee]

The argument for the strong nuclear force that was put forth concerns the amount of hydrogen that would exist and such. But, it then went on to say that the forces may not be adjustable, comparing them to pi.

[thylacine]

[ QUOTE ]
Another theory that he puts forward that I particularly enjoy, although I am the first to admit it is entirely random speculation and has no evidence to support it, is the idea that universes give 'birth' to other universes through black holes or some other mechanism, and that there is something about the universes that are amenable to life that are ALSO amenable to spawning these other, daughter universes. Its similar to why we see things that prefer to stay alive. There is nothing special about things that want to live, its just that the things that dont want to live aren't around anymore. There is nothing special about universes that like to form black holes and are amenable to life, its just that the ones that aren't don't make more universes and so quickly die out.

Like I said, completely unsupported but it has some aesthetic quality, I think.

[/ QUOTE ]

Lee Smolin promotes this idea in his book "Life of the Cosmos". I personally believe this is what actually happens. However, I would call this an evolutionary theory, which I believe is quite different to the anthropic principle.

[Magic_Man]

[ QUOTE ]
[ QUOTE ]
Another theory that he puts forward that I particularly enjoy, although I am the first to admit it is entirely random speculation and has no evidence to support it, is the idea that universes give 'birth' to other universes through black holes or some other mechanism, and that there is something about the universes that are amenable to life that are ALSO amenable to spawning these other, daughter universes. Its similar to why we see things that prefer to stay alive. There is nothing special about things that want to live, its just that the things that dont want to live aren't around anymore. There is nothing special about universes that like to form black holes and are amenable to life, its just that the ones that aren't don't make more universes and so quickly die out.

Like I said, completely unsupported but it has some aesthetic quality, I think.

[/ QUOTE ]

Lee Smolin promotes this idea in his book "Life of the Cosmos". I personally believe this is what actually happens. However, I would call this an evolutionary theory, which I believe is quite different to the anthropic principle.

[/ QUOTE ]

There's a brief discussion of this in "The Elegant Universe." Incidentally, this theory can actually be proven (sort of) with further insight into black hole formation. If the theory is true, then we expect to find ourselves in an "average" universe which is optimized for black hole production. If we find that the constants in question are the optimum values for production of black holes, then the theory becomes very strong.

~MagicMan

[RetiredAt22]

theyve proved the big bang - big crunch theory wrong in the early stages of M theory. basicly there wasnt enough matter in the universe found to close it on itself which would warrent a big crunch.

[gull]

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I think most cosmologists are pretty comfortable invoking the anthropic principle.

[/ QUOTE ]

I'm not so sure about this. The string theorist that I know best is in the camp that doesn't like it.

For example, in the past, the reasoning for our universe being three dimensional was randomness. In the multiverse, it just so happened that we got the 3D universe. However, very new equation suggest that universe brane collisions in the multiverse will cause all of the universes to eventually reach a stable equilibrium at three dimensions.

I have no expertise in this area, but I think the anthropic principle can be taken too far.

[thylacine]

[ QUOTE ]
theyve proved the big bang - big crunch theory wrong in the early stages of M theory. basicly there wasnt enough matter in the universe found to close it on itself which would warrent a big crunch.

[/ QUOTE ]

This is like saying that the Atkins diet proves that Fred is taller than Bill. /images/graemlins/blush.gif