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io9.com | Sept. 6, 2010
The strength of the electromagnetic interaction, one of physics's most fundamental constants, is actually very slowly changing, and has different values in different parts of the universe. This amazing find could help us find a grand unified theory of physics.
Known as the fine-structure constant and generally represented with the Greek symbol α, this constant is so basic that it doesn't even have dimensions - it's just a value approximately equal to 1/137. No less than Einstein's General Theory of Relativity says that α should be constant at all times and all places in the universe...and yet that's not what the new data is telling us.
A team of physicists at Australia's University of New South Wales have been studying the light from distant quasars since 1998, hoping to spot tiny changes in the value of α by calculating the chemical composition of gas clouds the light passed through on its long journey to Earth. Their study of the northern sky revealed that α appeared to be about 1/10,000 smaller billions of years ago, although those findings have not gained widespread acceptance just yet.
Their latest result complicates the picture still further. They've turned their attention to the southern sky, which reveals a totally different side of the universe. Analysis of the southern sky quasars shows α was 1/100,000 larger in the distant past. That suggests α varies with space as well as with time, and the researchers have dubbed this variation the Australian dipole. Their findings appear to have a very strong statistical significance - there's less than a 1 in 15,000 chance that these numbers are just random fluctuations.
The results seem to overturn Albert Einstein's notion of equivalence, a bedrock of general relativity that says α is invariant throughout time and space. That's actually good news for some theoretical physicists, as some leading candidates for a grand unified theory require equivalence to be quietly tossed aside. One major reason for this is that certain theories require the existence of extra hidden spatial dimensions, and those dimensions would seem to require α to vary.
This finding also has implications for our place in the universe, which might be even lonelier than we thought. Physicists have long realized how unlikely our existence is, as it requires the careful fine-tuning of several fundamental constants to values that could allow complex structures like stars, planets, and ultimately life to form. But if α has different values elsewhere in time and space, then that means our sliver of space-time is one of the very few places where life as we know it could exist.
[Physical Review Letters and arXiv]