Physicist Paul Davies enthuses in the Guardian on the possibility that the Cryogenic Dark Matter Search in Minnesota might have detected “the first faint hints” of Weakly Interacting Massive Particles [WIMPs], as reported by the BBC and the Guardian, before cautioning “it is too soon to open the champagne”. A more sceptical Peter Woit has pointed out that the two possible candidate events identified, from two years worth of observations, are not statistically significant against predicted background noise – there’s a 23% chance that’s exactly what they are. And the published paper itself admits that small tweaks to the assumed values used to predict that noise would remove even those two events as potential candidates. As this Science Now article notes
So should the CDMS result be taken as an observation of dark matter? “Absolutely not,” says Edward Thorndike, an experimental particle physicist at the University of Rochester in New York state. The 25% chance that the purported “signal” is actually just a few extra background events is far too big to justify any claim of discovery, he says. “If you’re going after something that’s going to send you to Stockholm, [that probability] better be well below 1%.” Even so, Joseph Lykken, a theorist at Fermilab, says he’s relieved that CDMS has finally seen something. WIMPs are predicted to exist by theories involving a principle called supersymmetry, which posits a heavy partner for every particle currently known. Had CDMS continued to see nothing, the results would have undermined those theories. So seeing something is better than seeing nothing, Lykken says. Gaitskell disagrees. Statistically speaking, he notes, with an expected background of one event, the probability of seeing zero events is almost the same as the probability of seeing two, so both are equally consistent with no WIMPS at all, he says. “As Christmas presents, they’re both a pair of socks.”
Evidence of WIMPs, a new form of matter predicted by supersymmetry, is much sought after by the string hypothesists. But that proof, or otherwise, seems more likely to emerge from the worlds highest-energy particle accelerator than the former mine in Minnesota. And, as the Nasa article points out, there are other potential candidates for “dark matter”. One of those other potential candidates, MAssive Compact Halo Objects [MACHOs] such as brown dwarf stars, could be identifed by WISE.But who knows what will be observed?
“Tis not unlikely, but that there may be yet invented several other helps for the eye, as much exceeding those already found, as those do the bare eye, such as we may perhaps be able to discover living Creatures in the Moon, or other Planets, the figures of the compounding Particles of matter, and the particular Schematisms and Textures of Bodies.” [Robert Hooke 1665]