One of the biggest mysteries of astrophysics is being unraveled deep underneath a mountain less than 100 miles from Rome. The place is the Gran Sasso Underground Laboratory: Situated along an expressway tunnel underneath Gran Sasso mountain, the lab and its collection of galleries is protected from the surface's billions of data-distorting particle events by thousands of feet of rock. What should be able to travel down here are dark matter particles called WiMPs (weakly interacting massive particles).A lot of the research here involves neutrinos, a chargeless and nearly massless particle that travels near the speed of light. But the XENON100 experiment deals with detecting WiMPs. The idea is that the particles should be detectable passing through a large amount of the element Xenon, which happens to have an exceptionally large nucleus for a WiMP to collide with and, thus, reveal a detectable signature. In a way, it even sounds simple.Yesterday, however, the XENO100 experiment released results showing, again showing no evidence of dark matter's WiMPs. Researchers found three candidate events, but two of those were disqualified by background radiation. One possibility does not a discovery make. Nevertheless, the new results show the highest sensitivity even recorded in the dark matter search. Which is good for future searches; we are, after all, still nearly at the beginning of the hunt.But this brings to mind our conversation with astronomer Stacy McGaugh a while back about his work with a dark matter alternate explanation.
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In any case, mysteries are always more fun than answers anyhow—and good for bloggers.Related:If you run the direct detection experiments for five years and don't find anything, you can abandon all hope, or you can go back to your models and tweak things until the dark matter particle is harder to find. What I'm saying is that you can only hope to falsify specific dark matter candidates. You might be able to prove it's not neutralinos, for example. But that doesn't preclude you from coming up with something harder to detect.
And the thing that worries me is that the more general process does not have a falsifiable finish to it. It is hard for me to know when to say when we should we quit.
Trapped Under Ice: Looking for Dark Matter in Antarctica
Scientists Hunt the Milky Way's Possible Heart of Darkness
Hunting the Universe's Biggest Something in its Deepest NothingReach this writer at michaelb@motherboard.tv.