WASHINGTON -- The keen eyes of the Hubble Space Telescope are shattering scientists' pet theories about two TC fundamental questions about the universe:
What is it made of? And how old is it?
Astronomers said yesterday that new photographs from Hubble rule out the widely held belief that dim red stars five to 10 times smaller than the sun make up most of the invisible matter in the universe.
Only about 10 percent of the mass of the universe is visible. The rest is so-called "dark matter" -- a mysterious substance that has baffled scientists since it was discovered 60 years ago.
"It's embarrassing for astronomers to admit we can't find 90 percent of the matter in universe," said Bruce Margon, chairman of the astronomy department at the University of Washington in Seattle. "Mother Nature is having a laugh today."
Another puzzle deepened three weeks ago, when a different group of astronomers reported findings from Hubble that seemed to show that the universe is younger than some of the stars in it -- a logical impossibility.
"Something is wrong with our theories," Alexei Filippenko, an astronomer at the University of California at Berkeley, told reporters in October. "We may have to consider some new, perhaps wild ideas."
The orbiting Hubble is producing a stream of pictures of stars and galaxies 100 times clearer than ground observatories can capture. In the process, it is upsetting widely accepted scientific notions.
"Mother Nature never gives us the answers we expected," said John Bahcall, leader of an astronomical team from the Institute of Advanced Study at Princeton, N.J., working on the dark matter problem.
For years, Mr. Bahcall said, the most popular theory among astronomers was that dark matter consisted largely of "red dwarfs," small, dimly burning stars composed of ordinary matter like the sun but visible only with the most powerful telescopes.
Mr. Bahcall and Francesco Paresce, leader of another team from the Space Telescope Science Institute in Baltimore, used Hubble to photograph areas of our galaxy, the Milky Way, checking for red dwarfs. Their findings astonished them.
"We expected the images to be covered wall to wall with faint red stars," Mr. Paresce said. "Instead, we found large open dark regions -- even distant galaxies shining through."
"Our results increase the mystery of the missing mass," said Mr. Bahcall. "I've been reluctantly dragged by nature to think the solution must be quite radical."
In contrast to the prevailing astronomical theory, some physicists speculate that dark matter is not composed of ordinary protons and electrons like the sun, Earth and the planets. Instead, they are hunting for exotic particles, as yet undiscovered, that may have been created in the Big Bang at the beginning of the universe.
Searches are under way for one such hypothetical particle, the axion, weighing only 10 trillionths of an electron. Another, the WIMP (for weakly interacting massive particle), would have 10 times more mass than a proton.
Until Hubble came along, most astronomers preferred the red dwarf theory.
"It was the most conservative and simplest solution -- that dark matter is like ordinary matter," Mr. Bahcall said.
But with red dwarfs ruled out, it is now the physicists' turn to lead the search.
"The physicists must be dancing in the halls today," sighed Mr. Bahcall.
Astronomers believe that the universe started expanding at the Big Bang -- 8 billion to 12 billion years ago -- and that it will continue to expand unless there is enough matter to put on the gravitational brakes.
If such matter exists, it is believed, eventually the universe will halt its expansion and begin to contract until it eventually collapses in on itself and, perhaps, restarts with another big bang.