Entry 1003, on 2009-05-05 at 20:29:13 (Rating 3, Religion)
One of the most puzzling things in modern science is how we seem to be continually discovering how the Universe is fine tuned to allow life to exist. This anthropic principle has been around for a long time now, but instead of gaining more insight into what might have "caused" the Universe to be the way it is we seem to be finding more instances which we can't explain.
Some examples of this fine tuning include the nuclear strong force (which holds together the particles in the nucleus). If this force was much weaker (estimates of the exact amount vary, but its a few percent), multi-proton nuclei would not hold together and hydrogen would be the only stable element, but if the strong force was just 1% stronger there would be no hydrogen because it would rapidly fuse into helium 2.
So the strong force must be a certain value for hydrogen to be abundant. Hydrogen is a major component of organic molecules and in water. Without it life could not exist.
It is possible (but not necessarily likely) that life might be able to exist based on entirely different processes than we currently know about. For various reasons this is unlikely but I don't want to explain that fully here. And are there any fine tuned parameters which would stop other types of life existing?
There is evidence that the cosmological constant must be fine-tuned to within one part in
10^50 for the Universe not to have entered a runaway expansion phase which would have prevented the formation of stars. Without stars no elements beyond lithium would exist making almost any imaginable form of life impossible.
There are many more examples of fine tuning of constants which you can research at Wikipedia and other sources (the Wikipedia article is titled "Fine-tuned universe").
So what's the answer? Well we just don't know. A theory which was considered on the fringe of science in the past but which seems to be gaining ground recently is the existence of a multiverse where an infinite (or very large) number of Universes exist with slightly different conditions. Our Universe just happens to be right for life but there are many (millions, billions, trillions, an infinite number perhaps) which aren't.
So how did we get to be so lucky that we are in a friendly Universe? Well that's simple: if it wasn't friendly we wouldn't be here, we would be in another universe wondering the same thing. The theory is neat but its difficult to think of a way to confirm or reject it so I do wonder whether it is really science!
Another possible explanation is that there is some reason the parameters are the value they are but we just don't know why yet. The numbers aren't predicted by theory, they just need to be established experimentally and plugged in to the equations. This is not good! Some string theorists claim that they might be able to predict the values using advanced string theory but we have been waiting for a viable string theory for many years now so that idea is far from settled.
The final possibility (you knew this was coming right, based on the title) is that god created the Universe in this form. I'm not really talking about a god in the form espoused by organised religions - those concepts are just childish nonsense. I'm talking about a supernatural entity, but one which we have no concept of at all.
There are three problems with this idea. First, theorising supernatural explanations has not traditionally been seen as viable science. While the definition of supernatural varies it usually implies something outside the natural world which can't be studied using conventional means.
The second problem is that, if god did create the Universe specifically for life he (of course god wouldn't be a "he" but let's just stick with that tradition here) didn't do a great job. There are many things in the Universe which can prevent life from surviving and the vast majority of the Universe just can't support it at all.
Finally there is the classic objection to god: if we need a god to explain the intricate structure of the Universe just imagine how much more intricate the god that created it must be! In other words we just make the whole problem worse: instead of having to explain a fine-tuned Universe we have to explain a fine-tuned god! Not only is that harder but we don't even have evidence a god exists. At least we know the Universe is there even if we don't know why!
So I think its fascinating to speculate about the fine tuned Universe but taking the easy way out and saying "god did it" is just another excuse not to really take the question seriously.
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