Aug 27 2010
I love it when researchers turn up new data or new theories to explain old data that expose some interesting new gap in what we think we know about the universe. It’s from those interesting new gaps — like absorption lines in what should be a smooth spectrum — that lead to new science and new technologies. (Those absorption lines, in 19th century observations of the Sun, ultimately led to quantum theory — and modern electronics and lasers.) This week we’ve had several instances of this.
You’re probably aware that the universe is expanding, and even that it seems to be expanding at an increasing rate. This somewhat counter-intuitive observation has been explained by “dark energy”, some unknown force that is accelerating the expansion. But many scientists aren’t comfortable with dark energy; the numbers for the vacuum energy don’t work out, and it seems to violate conservation laws. Now, this presumed expansion acceleration is based on measurements of very distant (edge of the universe distant) supernovas. If there’s another explanation for those measurements, then the acceleration may not really be happening and thus we don’t need dark energy to explain it.
There’s another problem. Models of the Big Bang that started the universe predict the creation of a certain amount of hydrogen, deuterium (heavy hydrogen), helium, and lithium. Our observations of the first three match pretty closely the predictions — but we only see about one-third the lithium we think we should.
Cosmologists Marco Regis and Chris Clarkson think they have an explanation for both of these discrepancies. Scientists make the assumption that the universe is pretty much the same in every direction we look, that — celestial bodies aside — there’s nothing special about one part space over any other. Regis and Clarkson point out here that the above problems go away if don’t assume the universe is homogenous. But there’s one other thing: if that’s the case, and there’s a huge bubble of space that is lithium-deficient, then why is Earth in the center of it?
Speaking on inhomogeneities in the universe, two different deep sky studies by the Keck telescope in Hawaii and the Very Large Telescope in Chile have turned up unexpected differences in what’s called the fine structure constant, considered to be one of the fundamental constants of nature (it relates to how strongly atoms bind their electrons). The really interesting thing is that while the Keck observations suggest that the fine structure “constant” was once smaller, the VLT observations suggest that it was once bigger. (Papers here and here.) These two telescopes — one in the northern hemisphere, one in the southern — look at two different regions of the sky. This, especially in light of Regis and Clarkson’s conjecture, raises all sorts of interesting questions. (Such as: What affect does this have on chemistry — and biology — in different regions of the universe? Would a space ship travelling such distances drag its own fine structure constant with it, or would it change according to local conditions? And, what causes this “constant” to vary, and could we reproduce that effect locally? Larry Niven had disintegrator guns that worked by “suppressing the charge on the electron”; could that really be possible? If you could reduce the charge on a proton, wouldn’t that make fusion easier?)
Somebody (Asimov?) once said that real scientific discoveries are less often heralded by “eureka!” than by “hmm, that’s odd.” Looks like we have several “that’s odd” moments going on. Cool!