The Largest Telescope on Ice Goes Hunting for the Most Elusive Particle in the Universe

Supernova 1987A sent a 10-second burst of neutrinos that demonstrated the potential of neutrino astronomy. Now, scientists are building a gigantic, deep-ice detector to get a better read on other sources of neutrinos. For an explanation of what you are seeing.

Half a century ago, a physicist "invented" the neutrino to make an equation balance. It was an odd particle, to say the least. Tiny, energetic, with neither mass nor electric charge, it was virtually undetectable.

In other words, the "can-it-be-for-real" neutrino was ready-made for scientific controversy. Scientists, as a rule, detest things they can't measure.

Hard to see or not, scientists now believe that nature is full of the shadowy neutrino. According to rough calculations, a hundred trillion neutrinos whistle through your body every second.

But not to worry--they pass right through.

Some varieties of neutrino can even pass right through the Earth --and giant clouds of interstellar gas and dust --without leaving a trace, and without being changed in the process.

Okay--they're weird enough.

But why make a big deal about neutrinos? They don't bug us. Don't we have better things to worry about?

Because that ability to pass through drifting interstellar crud allows neutrinos to carry messages from the far reaches of the universe. And because some neutrinos are fabulously energetic. They carry a bigger punch than even the most intense gamma ray.

That means they must originate in someplace exciting.

Just as you can't pull a hot coal from a cold fire, you shouldn't get "hot" neutrinos from "cool" sources like ordinary stars. These neutrinos, in other words, may be bringing signals of some of the hippest, blazingly hot stuff in the sky -- neutron stars (defined), active galactic centers (defined), and exploding stars, or supernovas.

Finally, according to some scenarios, lower-energy neutrinos comprise a large proportion of the mass --the stuff--in the universe. (In case you've been tuned out lately, astronomers think that up to 90 percent of the mass of the universe is invisible. That's a lot of something, by any measure; wouldn't it be be nice to know what kind of something).

So in astronomy, as in love and antiques, "hard-to-get" translates into "most-wanted." Says Francis Halzen, a theoretical physicist at University of Wisconsin-Madison, "The hope is that the particle that is almost nothing will tell us almost everything about the universe."

What is the source of these shy, unearthly particles? What can they tell us about the universe? Why are physicists trying to detect neutrinos in the deep ice of the Antarctic ice cap?

And how do they plan to find this elusive character, anyway?

Teachers: want to see some lesson plans based on the Antarctic, developed by Tom Spencer, a Virginia teacher who will spend two months at the pole, working with the AMANDA project?

Want to see the credits and factcheckers for this issue?