(c) 1995 Associated Press
PITTSBURGH (Jun 12, 1995 - 16:18 EDT) -- Primordial helium gas has been
found more than 9 billion light years from Earth and astronomers say it
may have formed in the big bang, the theoretical moment of supreme
violence that gave birth to the universe.
Astrophysicists discovered the helium, which can only be detected from
beyond the Earth's atmosphere, by using a special ultraviolet telescope
that was flown for the first and only time on the space shuttle.
A paper on the discovery was presented Monday at the national meeting of
the American Astronomical Society.
Arthur Davidsen, a Johns Hopkins University astrophysicist, said finding
the gas so far away "supports the whole idea of the big bang."
"One of the major predictions is that the universe after the big bang was
filled with about 90 percent hydrogen and 10 percent helium, he said.
"This gas filled all of space and was very, very hot."
Eventually the gas cooled -- to only a few million degrees -- and
condensed to form stars and galaxies. All other elements, including those
that built planets and life itself, are thought to have been formed in the
fiery life and death of stars.
"This helium is not any exotic matter," Davidsen said, but is part of the
elemental origin of all matter. "This was created in the big bang and we
were created out of it," he said.
Hydrogen and helium born in the big bang have long been thought to exist
still in the universe. Astronomers have sought evidence of it for more
than 30 years. But the search with conventional, ground-based instruments
has been without success.
It is believed the gas atoms cannot be seen because they have been ionized
-- stripped of electrons -- making them invisible to instruments peering
through the Earth's atmosphere. Even the Hubble Space Telescope lacks the
equipment needed to see the gas.
But Davidsen and others believed that a telescope looking in the far
ultraviolet spectrum from space could detect at least part of the elusive
gas. They reasoned that helium, which has two electrons while hydrogen has
only one, would be harder to ionize and, thus, more easily found.
"We thought that helium, while a smaller percentage of the gas from the
big bang, would more readily be detected than hydrogen," Davidsen said.
"But we had to build a very special telescope to do it."
The telescope was flown aboard the space shuttle Endeavour and focused on
a powerful quasar star some 10 billion light years away. It was hoped that
the spectra of the light from the quasar would reveal the gas deep in
space.
"It's like a giant floodlight that illuminates 10 billion years of
intergalactic history," said Davidsen.
When Davidsen and his colleagues analyzed data from the Astro-2 mission,
they found the clear signature of helium.
And the amount of helium found was consistent with what theorists had
predicted would remain from the big bang. Using the accepted ratio of
helium to hydrogen, the astronomers could then estimate the amount of
hydrogen. All of the numbers fit the theory.
"It strongly supports the whole idea of the big bang," said Davidsen. "If
you find a tusk is poking through your tent, you can pretty well assume
that there is an elephant outside."
And the helium, he said, is the tusk of the big bang elephant.