A futuristic telescope buried deep under the ice in Antarctica has proved that it can detect high-energy particles known as neutrinos as they pass through Earth, presaging what researchers hope will be a whole new approach to deep-space discovery.

"I have done a terrible thing. I have postulated a particle that cannot be detected."

The results, produced by an international team of researchers from more than a dozen institutions, appear in the March 22, 2001 issue of the journal Nature.

Tiny and elusive

Neutrinos are among the most abundant and energetic particles in the universe; the Sun alone makes unfathomable quantities of them. But they are invisible, carry no electrical charge and have almost no mass. So they are tough to spot.

"A billion pass through our body every second," said Francis Halzen, a University of Wisconsin professor of physics. "There are a billion neutrinos in the universe for every proton," including "300 left over from the Big Bang in every cubic centimeter in the universe."

Here's why they are important:

Neutrinos are thought to emanate from the most energetic events that occur in the far corners of the universe -- quasars, gamma ray bursts, supernovae and black holes. Unlike photons, from which visible light and other forms of radiation are made, neutrinos can zip across the cosmos unimpeded through strong magnetic fields, through clouds of interstellar gas and dust, and even through the hearts of stars.

"Just like optical telescopes catch light emitted in cosmic objects, we hope to catch cosmic neutrinos and use them as messengers giving us information on the sites where they are produced," Halzen told SPACE.com.

First findings: An important test

Halzen and his colleagues say they have used the AMANDA telescope (Antarctic Muon and Neutrino Detector Array) to spot neutrinos created high in Earth's atmosphere. These neutrinos are produced when cosmic rays crash into nitrogen and oxygen nuclei in the atmosphere. They are less energetic than the cosmic neutrinos thought to come from deep space.

"This is a well understood source of neutrinos, which we use to calibrate the experiment," Halzen said. "Now we can move on and concentrate on cosmic signals."

Neutrinos were predicted in the early 1930s by physicist Wolfgang Pauli in order to solve a problem with an equation. "I have done a terrible thing,'' Pauli said later. "I have postulated a particle that cannot be detected."

Enrico Fermi in 1933 named the particle the neutrino, which means "little neutral one," and did more calculations. But the first neutrino detection was not made until 1956, when Frederick Reines and Clyde Cowan found evidence of neutrino interactions in a mixture of liquid near a nuclear reactor.

It's good work, if you can get it: Pauli received the Nobel Prize in 1945, Fermi picked one up in 1938 and Reines scored a piece of the Nobel pie in 1995.

Next page: How AMANDA works, plus future neutrino detectors