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Entropy and the universe

I spend most of my day thinking about the precise configuration of votes in the Senate. Seems complicated. Then I read physicist Sean Carroll talking about the very nature of the universe and, well ... my day seems less complicated.

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.

Incidentally, the Senate exhibits much lower entropy than one might think, given that the 60-vote Senate means that literally anyone's vote could be the decisive vote, with all the fame and pork and access that that entails.

By Ezra Klein  |  November 18, 2009; 3:00 PM ET
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"The anthropic principle is just not enough to explain this."
Why not? If the universe had started as high entropy, we (as very low entropy beings in a very low entropy planet/solar system/galaxy) wouldn't be around to observe it. So if there are multiverses, we'll only exist in the one that allows our existence.

Posted by: _SP_ | November 18, 2009 3:14 PM | Report abuse

Actually the Universe taken as a whole is significantly EASIER to understand than the particular combinations of personalities that inhabit the Senate.

But when you ask yourself the question "what could have happened differently?" you realize that the entire course of human history is a series of distressingly arbitrary circumstances.

Posted by: PhD9 | November 18, 2009 3:22 PM | Report abuse

The idea of our universe being created out of low-entropy circumstances in some higher-level multiverse just seems to beg the question. You'd have to ask, how did *that* one get started? And since we'd know nothing about such a multiverse, if it existed, it's really no different than assuming the existence of God.

Posted by: rt42 | November 18, 2009 4:23 PM | Report abuse

SP, the point is that the real universe has an enormously lower entropy than would be required by any conceivable anthropic criterion. You don't need 100 billion galaxies with 100 billion stars each just for us to exist here.

rt42, the previous universe was not low-entropy; it had a high entropy. Otherwise, as you say, you wouldn't be explaining anything.

Posted by: seanmcarroll | November 18, 2009 6:13 PM | Report abuse

The great Issac Asimov had a short story that directly addresses this question. In fact it's called "The Last Question." It's so well done that I don't want to give away the ending. Just find it and read it.

Posted by: durangodave | November 18, 2009 6:19 PM | Report abuse

SP, you are correct, and Sean Carrol, you are a very funny guy, because the phenomena that define the habitable zones of the Goldilocks Enigma do not apply only to the Earth, but extend to include every planet in every galaxy that developed under similar circumstances as ours did. There are other scientists who know this and have made the "biocentric" nature of the physics known to anyone who actually wanted to understand the AP, and I know from first hand experience with you that this does not include you.

Not to mention the fact that you actually know very little about the many anthropic coincidences that are required for life:
Is The Anthropic Principle Too Weak?
The Goldilocks Enigma... Again...

And finally, we have the real reason why Sean Carroll is conveniently ignorant of the facts:

If I were posters... I wouldn't even feed this troll.

Posted by: Ryals | November 19, 2009 9:14 AM | Report abuse

"The idea of our universe being created out of low-entropy circumstances in some higher-level multiverse just seems to beg the question. You'd have to ask, how did *that* one get started? And since we'd know nothing about such a multiverse, if it existed, it's really no different than assuming the existence of God."

My infantile attempts at thinking about the Last Question came to the conclusion that there must be many Gods that each were created by some super-god and each rule their own world. It didn't escape me that the super-god must in turn have been created by some higher-level god. At that point I gave up. Seems that I came pretty close to modern cutting-edge cosmology.

"the Senate exhibits much lower entropy than one might think"
Low entropy would imply a small number of possible configurations. Me seems the opposite is true.

Posted by: carbonneutral | November 19, 2009 11:25 AM | Report abuse

A near static yet expanding universe quite obviously wastes less energy to heat-death, (maximizes the available energy), than a wide-open expanding universe would. This configuration also disseminates energy more uniformly, again, an obvious energy conservation law at work.

Ain't the confusion of the cutting-edge wonderful?

Posted by: Ryals | November 19, 2009 4:35 PM | Report abuse

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