spacetoday.net: Astronomers find new evidence for dark energy

Posted: Tue, Nov 12, 2002, 8:58 AM ET (1358 GMT)
Astronomers have used radio telescope observations to conclude that two-thirds of the universe is made of a bizarre "dark energy" that may explain why the expansion of the universe is accelerating. In a paper published in Physical Review Letters, a group of astronomers led by Ian Browne of the Jodrell Bank Observatory in the UK conducted a survey at radio wavelengths, looking for distant quasars that had been gravitationally lensed by a galaxy between the quasar and the Earth. Their results — that one in 700 quasars in gravitationally lensed — was combined with previous surveys of the numbers and types of galaxies. To explain the number of splittings observed, twice as many as expected if there was no dark energy present, astronomers concluded that there must be a significant amount of dark energy, with long-range antigravity properties, in the universe. The findings confirm previous studies which also concluded that dark energy made up about two thirds of the universe, with dark matter, a type of matter with normal gravitational properties that eludes detection, making up most of the rest.