From deep-thinking physicist Sean Carroll:
If you didn't know any better, if you asked what the universe should be like, what configuration it should be in, you would say it should be in a high entropy configuration. ... There are a lot more ways to be disorderly and chaotic than there are to be orderly and uniform and well arranged. However, the real world is quite orderly. The entropy is much, much lower than it could be. The reason for this is that the early universe, near the Big Bang, 14 billion years ago, had incredibly low entropy compared to what is could have been. This is an absolute mystery in cosmology. This is something that modern cosmologists do not know the answer to, why our observable universe started out in a state of such pristine regularity and order — such low entropy. We know that if it does, it makes sense. We can tell a story that starts in the low entropy early universe, trace it through the present day and into the future. It's not going to go back to being low entropy. ... Our best model of the universe right now is one that began 14 billion years ago in a state of low entropy but will go on forever into the future in a state of high entropy.
Why do we find ourselves so close to the aftermath of this very strange event, this Big Bang, that has such low entropy? The answer is, we just don't know. The anthropic principle is just not enough to explain this. We really need to think deeply about what could have happened both at the Big Bang and even before the Big Bang. My favorite guess at the answer is that the reason why the universe started out at such a low entropy is the same reason that an egg starts out at low entropy. The classic example of entropy is that you can take an egg and make an omelette. You cannot take an omelette and turn it into an egg. That is because the entropy increases when you mix up the egg to make it into an omelette. Why did the egg start with such a low entropy in the first place? The answer is that it is not alone in the universe. The universe consists of more than just an egg. The egg came from a chicken. It was created by something that had a very low entropy that was part of a bigger system. The point is that our universe is part of a bigger system. Then you can start to try to understand why it had such a low entropy to begin with. I actually think that the fact that we can observe the early universe having such a low entropy is the best evidence we currently have that we live in a multiverse, that the universe we observe is not all that there is, that we are actually embedded in some much larger structure.
Wow ... interesting theory, I'm not sure that he isn't leading the data a bit, but it certainly has a certain plausibility, at least.
2 comments:
Of course, the fact is that we exist and are sufficiently self-aware (ordered) to question why the universe is so ordered. I suggest that situation was _much_ more likely to have arisen in a relatively ordered (low entropy) universe.
Accordingly, the proposition that a low entropy universe was unlikely in some general sense is meaningless. Given the condition that intelligent beings are questioning the nature of their universe, I would suggest that the likelihood is high that they live in a low entropy universe.
It is a bit like knowing some one has thrown dice (each 1-6) totalling 10 - impossible if they only threw one die, unlikely if they threw 2 dice, but unexceptional if they threw 3 dice.
Bottom line - nothing about an event which only occurs once (that is, is truly unique, not one of a class of similar events) can be used as inference. Likelihood and probabilty are concepts properly applicable to repeated events.
Of course the corollary of my view is that it is very likely (IMO vitually certain) that there are other intelligent beings elsewhere in our universe.
It is furthermore very likely that some of them (about half, for lack of any evidence) are cleverer and more advanced than us. Unfortunately, a race that is clever and expansionary enough to reach us may not be particularly nice (the nice races who are ecologically balanced etc will not have the same pressure to expand and seek out new frontiers). Our fate could easily be comparable to that of the Australian Aborigines - pushed aside by more powerful and numerous aliens looking to exploit the resources of our part of the universe in ways we didn't even know existed.
But it is also very likely that any aliens are all so far away that they will never contact us - so who cares.
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