Entry 559, on 2007-06-22 at 19:48:59 (Rating 2, Science)
Why is the Universe the way it is? Why do so many factors (physical laws and constants, such as the gravitational constant) which don't appear to need any particular value combine to make a Universe where life can exist?
There seem to be three main theories to explain this: the fine-tuned Universe, the Multiverse, and God. The fine-tuned Universe theory says yes, our Universe is ideal for life and there are good reasons for it, we just don't really know what they are yet, although there are a few ideas around. The multiverse theory says our Universe is fine tuned purely through luck. There are an infinite number of other Universes which don't have the right characteristics for life but there is no life in them to wonder about those parameters. The God theory says God did it, and that's about all.
I am currently listening to an interview with prominent cosmologist Paul Davies who favours the fine-tuned Universe theory. He has the idea (its probably not sufficiently formal to be called a hypothesis or theory) that the act of observing the Universe changes the way the Universe is. Well its worse that that because he claims life actually changes the way the Universe was in the past. It sounds insane but its consistent with quantum mechanics which says that both the future and past are uncertain and that an influence going back in time is allowed. So the Universe is good for life because life wanted it that way. I like this theory because it fits in with current knowledge of quantum physics. But I just have this feeling that there is a lot more to understand about quantum physics, and when we do know more it might make this theory look untenable.
The Multiverse theory is perhaps even worse. The idea that there are many Universes - in fact probably an infinite number - all with different physical parameters is also a difficult concept to understand. But it does fit rather well with other current ideas in science: species are the way they are because the fittest survive and the rest disappear, the Earth has life because things just happened to be right here but other planets weren't quite right so they have no life. Why shouldn't these ideas be extended to the whole Universe? I personally like the Multiverse theory, and its probably the most accepted currently.
The God theory isn't really science because it really means nothing. The phrase "God did it" can be used to answer practically any question, but it really doesn't answer anything at all because its so vague. How could we test this? If someone said: God is an entity which exists in form X and he caused process X to make the Universe at time X. We could check the Xs and verify or reject the theory. Of course, we would then have to figure out where God came from and why he was the right type of God to make a Universe which was right for life, so we would be no better off. So I'm afraid I don't even really count this as a serious theory although its very popular amongst religious people. Its really just another example of the old "God of the gaps" phenomenon. Does science understand this phenomenon? No, well it must be God then.
The whole question about why the Universe is suited for life is very intriguing. Maybe when we have the next great theory in physics: one which combines quantum theory and relativity, we might see why the laws have to be the way they are, but it seems that at the moment we really just don't have a clue!
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