Friday, 25 October 2013

The reasons behind our fundamental constants

I've just watched an interesting talk by Gian Giudice. In this talk, Giudice presents his hypothesis that the value of the Higgs boson mass, which is approximately 126 GeV, is special: it is special because it falls within the small range of critical values that mean that the structure of our universe is on the brink of collapse. Luckily, the probability of such a collapse happening is so small, that this is only likely to happen inconceivably far into the future (phew!).

Of all the values the Higgs boson mass could take, why is it this one, one that puts the fate of our universe on knife-edge? Giudice believes that there could be a reason, using an effective analogy to explain why. Consider the much less mysterious phenomenon of sand dunes: the slope of sand dunes generally take a value between thirty and thirty five degrees, because the effects of the wind and the effects of gravity upon the sand mean that the slope is simply statistically likely to be within this range. And so the same can be said for the Higgs boson mass: there is a high statistical probability that its mass takes a value within the range that it does, due to two competing effects. What these effects might be caused by pose further questions to be explored.

This got me thinking about the other fundamental constants of the universe: Planck's constant, a fundamental constant of quantum mechanics; the speed of light in a vacuum, the constancy of which is the insight of Einstein's theory of Special Relativity; and the fine structure constant, which, if it were just four percent larger, would prohibit the formation of carbon and life as we know it. Do the values of these constants have reasons? Or are some of them simply what they are by pure chance?

My intuition has been that they have reasons. Our world is so intricate that I can't imagine that, when the universe was born, light simply took on a value of 3x10^8 m/s for its speed by chance. But until now, I couldn't understand what a reason might look like; what would possibly cause any fundamental constant to take on the value it does? I liked Giudice's talk because it helped me to understand how there could indeed be reasons behind such things.


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