Antarctic Hunt for Primordial Antimatter

Japanese and US scientists in Antarctica plan to search the edge of space for some of the rarest creatures in the universe - bits of antimatter from primordial black holes.

Antimatter is matter's exact opposite: electrons, protons and even atoms in reverse. The catch is that when antimatter meets matter, both are completely destroyed.

But a package of sensitive detectors suspended from a 40m cubic foot balloon could rise above 99% of the Earth's atmosphere to detect fragments of antimatter predicted decades ago by Stephen Hawking, the Cambridge cosmologist.

Professor Hawking proposed that antimatter could arrive in the form of what is now called "Hawking radiation" leaked from black holes. When he made the prediction, there was no evidence that black holes existed. These strange beasts are the remnants of collapsed stellar material, so massive and so dense that not even light can escape from them. But Prof Hawking proposed that something might get out, all the same.

The researchers have tested the equipment with short flights above the Canadian Arctic. Now they want to get the detectors 24 miles (40km) above the Antarctic, for a flight of at least 10 days.

"Our earlier, shorter flights have provided hints of the signature of Hawking radiation," said Akira Yamamoto of Japan's High Energy Accelerator Research Organisation. "With a longer flight and a greater 'harvest' of antiprotons, we might be able to show that Prof Hawking is right."

A balloon-borne experiment with a superconducting spectrometer (Bess) is a collaboration involving Japanese scientists, Nasa and the University of Maryland. One of the goals of Bess is to detect any antimatter left over from the creation of the universe.