Astronomer usually look up. But some astronomy is better conducted by looking down. Although the earth is opaque to the light, radio waves, x-rays, gamma rays and other forms of electromagnetic radiation that are the stock-in-trade of most astronomy, it is transparent to particles called neutrinos. Point a suitable telescope downwards, therefore, and the chances are that you will see nothing but neutrinos. Sink it deep under water, and you will get an even better view, since the water will help to screen out confusing radiation coming from above. This, at least, is the theory behind two rival machines being built at the bottom of the Mediterranean. Both NESTOR and AN-TARES will look for high-energy neutrinos, a little-studied form of radiation. These telescopes should give a glimpse of hot, dense regions of space that cannot now be examined because they absorb electromagnetic radiation at all wavelengths. That will be interesting, but not spectacular. With luck, though, NESTOR and AN-TARES will also reveal the first evidence of a form of matter called weakly interacting massive particles (WIMPS). That would rewrite understanding of the universe. Many physicists believe that WIMPS make up much of the universe's "dark matter". This is stuff that shows up because of its gravitational effect, but has otherwise been undetectable. If WIMPS exist, theory predicts that they contribute about ten times as much mass to the universe as the protons, neutrons and electrons of which familiar "normal" matter is made. If that is true, then planets, stars, galaxies and, indeed, people, are just scum floating on a sea of WIMPS.
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