Wednesday, April 09, 2014

Martin Reese. Just Six Numbers (1999)

     Martin Reese. Just Six Numbers (1999) The six numbers characterise our universe. This is how Reese describes them:
N: the strength of the electrical force that holds atoms together;
ε: the strength of the force that binds  the atomic nucleus together;
Ω: the amount of material in our universe;
λ: the force that expands the universe;
Q: the ratio of two fundamental energies;
D: the number of dimensions.
     If any one of these were too different, our universe would not exist, and we wouldn’t be here to wonder about those six numbers. This fact is referred to as the ”fine-tuning” of our universe. This freaks some people out. And the people who yearn for reassuring support for their religious fantasies have jumped on this fact as providing proof. In fact, it does no such thing. It suggests that there could be other universes with different combinations of those six numbers, and some theories appear to imply that such universes actually exist, although what “exist” means in a cosmos whose parts cannot know of each other is a nice question.
     Reese writes well, but I found too often that it was my prior reading about cosmology and physics that enabled me to understand him. He’s nicely modest about what’s known and unknown, and what may be unknowable. In the 15 years since he wrote, a number of speculations are on the verge of becoming hypotheses. The recent announcement of evidence for  gravity waves, ripples in the space-time fabric, is a step towards distinguishing between several proposals for a Theory of Everything. The notion of a multiverse is no longer mere speculation, and string theory may be examined again. There is hope that a model that unifies gravity with the other three forces is possible.
     Nevertheless, theories at the outermost boundaries of the knowable will always be more or less speculative. The strongest theories will be those that one the one hand imply what we can observe, and on the other require assumptions of what we cannot observe. Nature has a way of confounding our expectations, which is good: this helps us distinguish between viable and unviable speculations. Reese knows this. In his last chapter, he allows that a final Theory of Everything may not be possible. That would not be the end of science, however. Just because you have a good theory doesn’t mean you know all its implications, nor that you know all the ways in which it applies to what see around you. A good theory contains surprises.
     A good book, but you need some background to profit from it. **½

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