for National Geographic News
Late last month scientists working at NASA's Chandra X-ray Observatory announced that they had found proof of dark matter, the theoretical substance believed to make up more than a quarter of the universe.
But Glenn Starkman, a cosmologist at Case Western Reserve University in Cleveland, Ohio, is hitting back with a blast from the past.
He argues that dark matter might not exist and that the long-discredited substance known as ether is actually what influences gravity in the cosmos.
Dark matter is the prevailing scientific explanation for a puzzling phenomenon: Galaxies behave as if they contain much more mass than is visible to astronomers (see a computer simulation of dark matter).
According to theory, dark matter is the invisible mass that accounts for this behavior, and the undetectable substance makes up five times more of the universe than the matter we can see.
Starkman's controversial counterproposal is that the presence of ether in the universe better explains the galaxies' behavior.
His theories were recently reported in the August 26 issue of New Scientist magazine.
"Galaxies spin faster than they should, given the amount of matter we see in them. The possibility we've gone with for a long time is that there's some unaccounted-for mass generating that extra gravity," Starkman said.
"But the other possibility is that the amount of mass we see generates more gravity than we thought. That's where ether comes in."
The term "ether" is derived from Aether, the ancient Greek god of the upper sky and the personification of space and heaven.
The scientific concept of ethera background medium that pervades the universehas been around for hundreds of years.
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