NOBLE LAUREATES: Three scientists who helped unlock secrets hidden inside the stars have shared the 2002 Nobel prize for physics. Two delivered conclusive proof about the sun's energy source and the third developed the X-ray telescope, making it possible to detect distant stars and black holes.
The winners were announced yesterday by the Royal Swedish Academy of Sciences. They are: Dr Raymond Davis and Dr Riccardo Giacconi of the United States, and Dr Masatoshi Koshiba, the third Japanese winner of a Nobel prize in as many years.
Dr Davis and Dr Koshiba will share half the $1-million prize for their pioneering work on astrophysics and the detection of tiny sub-atomic particles called neutrinos. Dr Giacconi takes the second half of the prize for his ground-breaking work on X-ray radiation coming from beyond the earth.
"This year's Nobel laureates in physics have used these very smallest components of the universe to increase our understanding of the very largest: the sun, stars, galaxies and supernovae," the academy said in a statement. "The new knowledge has changed the way we look upon the universe."
Work by Dr Davis (87), of the University of Pennsylvania, and Dr Koshiba (76), of the University of Tokyo, opened up a new field of science called neutrino astronomy. They proved the existence of neutrinos, particles produced inside the sun and other stars during the fusion of hydrogen into helium, the stellar energy source. In effect they confirmed the theory that the fusion reaction produced the sun's massive energy.
Thousands of billions of solar neutrinos are estimated to pass through our bodies every second with little or no effect because the tiny particles react only weakly to matter. This also makes it a tremendous challenge to capture them.
Dr Davis, who has Alzheimer's disease, used a 615-tonne tank full of cleaning fluid hidden deep in a mine to record the passage of neutrinos. Neutrinos passing through the tank in the 30-year study, changed atoms of chlorine in the liquid into atoms of argon which he could count.
Dr Koshiba, in a separate experiment, used a huge tank of water installed in a mine in Japan. He recorded the minute flashes of light caused by the neutrinos interacting with the nuclei of the water molecules. By registering the speed and direction of the particles, he proved that the neutrinos came from the sun.
Dr Giacconi (71) pioneered X-ray astronomy, which uses a special telescope that records signals coming from distant stars.
His work used the X-rays arriving from stars too far away to be seen to provide information about them. It also provided evidence for the existence of black holes - collapsed stars with tremendous gravitational pull that trap everything around them including light.
The academy described Dr Davis's work as "an achievement considerably more difficult than finding a particular grain of sand in the whole of the Sahara desert". Their scientific contribution also provided more mundane discoveries.
Additional reporting: Reuters