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A Picture Worth a Thousand Answers
Date Posted: Wednesday, February 12, 2003
(A Bible, Science, and History Tidbit from Genesis Proclaimed Association)
Scientists Capture Best Image Ever of
Universe's Beginning
By Rob Stein
Washington Post Staff Writer
Wednesday, February 12, 2003
A powerful satellite has captured the best picture ever taken of
the infant universe, an image so detailed that scientists said it answers
some of the most important questions about the cosmos, including when it
was born and how it will probably die.
The image, created from a year's worth of data collected by a NASA probe 1
million miles from Earth, has solved long-standing puzzles, such as what
the universe looked like right after it was forged in the violent inferno
of the big bang, when the first stars blinked on in the coalescing heavens
and what kind of matter makes up the expanding universe that exists today.
Astronomers calculated that the universe is 13.7 billion years old, that
the first stars lighted up just 200 million years after the cosmos was
born, and that it will expand forever, thinning and cooling until it
eventually reaches nothingness.
"These results are truly profound, and give us insights into some of
the most fundamental questions that humans ever posed," said Edward
J. Weiler, NASA's associate administrator for space science.
The image was created from the most sensitive temperature measurements
ever made of a faint glow that is dissipating through space, the last
remaining light from the blinding flare of the big bang. By detecting
subtle variations in the glow's warmth, scientists were able to discern
the primordial structure of the universe a mere 380,000 years after its
birth.
From that, scientists calculated even further back in time to determine
the conditions that must have existed at the moment of cosmological
conception. They also extrapolated forward to measure the matter that
makes up the universe today and, from that, predict what it will do in the
future.
"I think every astronomer will remember where they were when they
heard these results," said John Bahcall, a leading astrophysicist
from Princeton University. "I certainly will. This announcement
represents a rite of passage for cosmology from speculation to precision
science. I personally am thrilled by the results."
Because of the time it takes light to travel, the new data show the
universe almost immediately after the big bang, the furthest back
astronomers have ever been able to see. It shows clumps of matter just
beginning to cool and congeal from the fireball of the big bang into what
would eventually become all the galaxies in the universe.
From that, astrophysicists were able to calculate the age of the universe
with unprecedented precision. Earlier estimates had ranged from 8 billion
to 20 billion years, but in recent years they narrowed to somewhere
between 12 billion and 15 billion years. The new estimate of 13.7 billion
years has a margin of error of only 1 percent, compared with about 30
percent for the best previous estimates.
The data strongly confirm the prevailing big-bang theory and allow
researchers to test various versions of the "inflation theory,"
which holds that even before the universe was one second old it had
expanded dramatically.
"We've now laid the cornerstone of a unified cosmic theory, by having
a new set of very accurate numbers that describe a wide range of cosmic
measurements," said Charles Bennett of NASA's Goddard Space Flight
Center in Greenbelt, who led the project. "We have not answered all
the questions. But we've certainly turned a corner." He announced the
findings at a briefing at NASA headquarters.
The data also have enabled scientists to produce the most exact
calculation ever of what the cosmos is made of today. It turns out that
only 4 percent of the universe is made up of atoms with known forces such
as electromagnetism and gravity, the ordinary stuff that makes people,
potatoes, porcelain and everything else that humans know. Twenty-three
percent of the universe is made from mysterious unseen material dubbed
"dark matter" because scientists know so little about it. The
remainder -- 73 percent -- is made up of yet another poorly understood
force called "dark energy."
"I was very skeptical of this concoction," Bahcall said.
"But the results have really convinced me. This is the only
conclusion one can come to, strange as it is. It's fantasy, but you know
it's fantasy turned real. It's unbelievable but true."
One possible explanation for dark energy is the "cosmological
constant," an energy in empty space that would oppose gravity and was
originally predicted by Albert Einstein, who later discarded it as his
biggest blunder.
This dark energy, astronomers said, is the reason why the universe seems
to be expanding at an accelerating rate. There is not enough normal matter
to counteract the effects of dark energy, which is also known as
anti-gravity. As a result, the astronomers said, they can now predict
confidently that the universe will continue to expand forever instead of
eventually collapsing back in on itself in a "big crunch," as
some had predicted.
"The universe is expanding and cooling. That will continue happening.
The universe will get colder, the temperature will drop and things will
move apart. The density will go towards zero," Bennett said in an
interview.
"It will dissipate and peter out, as opposed to the alternative of
having the universe close back in on itself. If you had to choose how the
universe would end, by fire or ice, this is the ice answer."
One of the biggest surprises from the new data is that the first
generation of stars to shine in the blackness of space ignited just 200
million years after the big bang. Previous estimates were that the first
stars were born perhaps as many as 1 billion years after, but no sooner
than about 500 million years.
The new picture of the universe comes from the first data collected by the
Wilkinson Microwave Anisotrophy Probe (WMAP), a small $145 million
satellite launched on a Delta 2 rocket June 30, 2001. The craft is
equipped with a suite of instruments designed to gather the most precise
measurements of cosmic microwave background radiation, the technical term
for the light left over from the big bang.
Scientists have likened the light to an archaeological artifact, something
they can examine to validate theories about the universe and gain
fundamental insights into its creation, composition, geometry and fate.
"It's a direct remnant of the big bang," Bennett said.
Scientists are highly confident in the new measurements because every one
fits perfectly into what would have been expected based on existing
theories, and matches precisely complementary measurements gathered
independently by other instruments, including the powerful Hubble Space
Telescope.
"What we find when we do this is remarkable -- it all fits,"
said David Spergel, a Princeton scientist involved in the project.
"It's a lot like matching fingerprints."
The average temperature of the light is 4.9 degrees Fahrenheit above
absolute zero. WMAP can detect the most subtle variations in light's
temperature, which varies only by millionths of a degree.
The researchers compared the map of the sky they created from the WMAP
measurements to a variety of simulations of what physics would predict
based on competing theories about the universe.
"We are now for the first time in a position to sort through specific
inflation theories," Bennett said.
© 2003 The Washington Post Company
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