A high-altitude balloon experiment above the Antarctic may have just seen a possible signature of the mysterious “dark matter” thought to make up 85 percent of the mass of the universe–but as yet, completely unseen and not at all completely understood. (Via Nature News.)
The experiment, the Advanced Thin Ionization Calorimeter (ATIC), spotted a surplus of high-energy electrons coming from…somewhere. This matches something the PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics–don’t you love space-exploration acronyms?) satellite mission turned up earlier this year
Electrons at this particular energy could be the result of heavy dark-matter particles colliding, which according to Dan Hooper, a theoretical physicist at Fermi National Accelerator Laboratory, is “certainly the sexiest of the possibilities.”
Sexy and, to non-physicists, more than a little weird:
The exact nature of the dark-matter particles that produce electrons is uncertain, but one idea is that they may be ordinary particles that spend part of their lives in a compact extra dimension of space. Whereas the particles would appear relatively stationary to observers trapped in three spatial dimensions, they could be moving at ultra-high speeds in a fourth spatial dimension. At high speeds, they would create a gravitational force that could be felt by matter trapped in three dimensions of space-time. “It’s very wild,” Hooper says.
I’ll drink to that!
Of course, there are other possibilities. In particular, the electrons could be coming from a nearby pulsar, the fast-spinning remnants of a supernova.
How do we figure out? More experiments, of course. A new orbiting telescope called Fermi can spot electrons and positrons (though it’s designed to hunt for high-energy X-rays), and thus may confirm the data, or even pick up other high-energy particles that could be produced by dark-matter collisions.
Check back in the spring.
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Philip Pullman is smiling.
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