英语时差:AMANDA望远镜
Nowadays we have telescopes of all different sorts, from ones that orbit the planet to giant radio dishes in the deserts. The neatest new idea for a telescope, though, is a deep hole in the pole. AMANDA II stands for Antarctic Muon and Neutrino Detector Array. You know what “Antarctic” means: this baby lives at the south pole. The international project members who built it dug half a mile down into polar ice. Then they lowered in a series of light detectors, on the lookout for one of the most elusive particles in the universe: the neutrino. Neutrinos are so tiny and zippy they can pass through the entire planet without hitting anything. Every now and then, however, one will collide with something–say a water molecule in the crystal-clear polar ice. When neutrino meets molecule, tell-tale flashes are given off, and AMANDA registers these. Now comes the really neat part: that makes AMANDA into a kind of telescope. Imagine some cool extra-galactic event, like a supernova or the collision of two black holes. This gives off a stream of neutrinos, some of which travel to earth and make it almost through the planet, only to tag a water molecule on the way out. AMANDA spots the collision and, because neutrinos travel in straight lines, tells exactly which direction the neutrino came from. With that, scientists can generate a neutrino map of the sky. Telescopes are old, but a neutrino telescope is new. Odd as it may sound, this deep hole in the ice is helping researchers dig even deeper into space and time.
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