Sean Carroll is a physicist at Cal Tech and a proponent of the idea of the multiverse, the notion that reality consists of an infinite number of "universes". He was interviewed recently by the LA Times and the first part of the Q&A provides us with a good explanation of what the multiverse hypothesis is.
The most interesting part of the interview for me, though, was the second part. Carroll is inclined toward belief in a multiverse because, among other things, it provides a possible naturalistic explanation for a very puzzling aspect of our universe. Our universe started out, according to the standard Big Bang model, in a state of exceedingly low entropy. This means that it was very highly ordered. It's like mixing hot and cold water and having all the hot molecules, just through their random motions, all collect on one side of the basin and the cold molecules all collect on the other. It's possible but highly improbable.
Carroll compares it to opening a new pack of cards and finding the cards arranged in sequence by suit. We're not surprised by that when we buy a new deck of cards because we know that the cards were put into order at the factory. Since the universe was highly ordered when it was brand new, which is an extraordinarily improbable state, there must have been some other universe, or factory, from which it came because for it to have started out this way by chance is breathtakingly improbable.
Let's read the interview:
So what's the problem?
If you really believed the conventional story that the Big Bang was the beginning, that there was nothing before the Big Bang, I think that's a very difficult fact to explain. . . .
There's no law of physics that says it should start at a low-entropy state. But the actual universe did that.
So you think the way the universe began is unnatural?
Low-entropy configurations are rare.
If you take a deck of cards and you open it up, it's true that they're in order. But if you randomly chose a configuration of a deck of cards it would be very, very unlikely that they would be in perfect order.
That's exactly low entropy versus high entropy.
The universe is more than what we see?
The reason why you are not surprised when you open a deck of cards and it's in perfect order is not because it's just easy and natural to find it in perfect order, it's because the deck of cards is not a closed system. It came from a bigger system in which there is a card factory somewhere that arranged it. So I think there is a previous universe somewhere that made us and we came out.
We're part of a bigger structure.
Are you saying that our universe came from some other universe?
Right. It came from a bigger space-time that we don't observe. Our universe came from a tiny little bit of a larger high-entropy space.
I'm not saying this is true; I'm saying this is an idea worth thinking about.
Indeed it is, so let's think about it. What Carroll doesn't mention is that the low entropy of the playing cards is due to the fact that there was an intelligently designed system at the factory which was intentionally constructed to place the cards in an orderly sequence. If there was a "factory" which produced a low entropy Big Bang then, following Carroll's deck of cards analogy, the factory should consist of an intentional, intelligent agent.
Carroll is asked by the interviewer about whether God has a role in his physics, and he pretty much answers no, but everything he has said in the interview up to that point leads to the conclusion that whatever produced the universe, it very likely was intelligent.
Carroll thinks that our universe was somehow spawned by another world in the multiverse, but this just sets the problem back a step. It doesn't really explain why or how our universe had such low entropy at it's beginning. It's as if his deck of cards was packed in perfect sequence just by coincidence. He's left clinging to the very unscientific belief that there are an infinite number of universes with an infinite number of initial conditions and that one of them just has to have had the initial conditions ours did.
The problem is that we know intelligent agents can produce low entropy states, but we don't have any evidence that there are an infinite number of other worlds, or if there are, that there were an infinite number of initial conditions. Each of the infinite worlds could have the exact same initial conditions for all we know. Postulation of the multiverse is an act of metaphysical desperation that enables those who are disinclined to believe in a purposeful creation to avoid having to draw the conclusion that it sure looks like it was intentionally designed.
It's funny that the multiverse hypothesis is an acceptable topic for discussion among scientists and would be a fascinating topic for a high school physics class, even though there's not a shred of empirical evidence for it. Yet our students must at all costs be protected from exposure to the toxic implications of believing that our universe is the only one that exists. They must not, on pain of litigation, have it suggested to them that a low entropy Big Bang entails the possibility of a purposeful origin to the universe.
RLC
