From The Economist:
Richard Feynman, Nobel laureate and physicist extraordinaire, called it a “magic number” and its value “one of the greatest damn mysteries of physics”. The number he was referring to, which goes by the symbol alpha and the rather more long-winded name of the fine-structure constant, is magic indeed. If it were a mere 4% bigger or smaller than it is, stars would not be able to sustain the nuclear reactions that synthesise carbon and oxygen. One consequence would be that squishy, carbon-based life would not exist.
Why alpha takes on the precise value it has, so delicately fine-tuned for life, is a deep scientific mystery. A new piece of astrophysical research may, however, have uncovered a crucial piece of the puzzle. In a paper just submitted to Physical Review Letters, a team led by John Webb and Julian King from the University of New South Wales in Australia present evidence that the fine-structure constant may not actually be constant after all. Rather, it seems to vary from place to place within the universe. If their results hold up to the scrutiny, and can be replicated, they will have profound implications—for they suggest that the universe stretches far beyond what telescopes can observe, and that the laws of physics vary within it. Instead of the whole universe being fine-tuned for life, then, humanity finds itself in a corner of space where, Goldilocks-like, the values of the fundamental constants happen to be just right for it.