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New Images Show Infant Universe

THE NATION

Astronomy: A team from Caltech obtains the earliest visible signals from the big bang.

May 24, 2002|USHA LEE McFARLING | TIMES STAFF WRITER

Using radio telescopes set on a high, windy plateau in the Chilean Andes, a team of Caltech astronomers has obtained the most detailed snapshots yet of the early universe, revealing for the first time the tentative seeds of matter and energy that gave birth to all structure in the cosmos.

The images are a swirling, tie-dye tableau of bright yellow and orange, splotched with brighter areas that reveal temperature differences in the fading glow of the big bang.

These cosmic fossils show the first subtle structures to emerge from the primordial soup that existed just 300,000 years after the universe was created.

"They really are seeing a whole new class of structures that were previously unknowable," said Alan Guth, a particle physicist at MIT who was not involved in the research.

The new images open a portal onto creation, confirming several radical notions about how the universe could have exploded out of a tiny speck. They also help solve the biggest geometry problem of all time, showing that the universe is indeed flat.

The first images of this ancient light, called cosmic microwave background radiation, could reveal only huge structures hundreds of millions of light-years across. The new images show exquisitely fine detail: blotches of light smaller than the moon. The earlier pictures, taken a decade ago, were dubbed the face of God. These are the freckles.

Like a form of cosmic DNA, the freckles are blueprints for the walls and bubbles of galaxies that form the architecture of our universe.

The feat was possible only because the cluster of telescopes used in the experiment was able to detect temperature differences of a ten-thousandth of a degree. The images show darker, redder areas that are colder and less dense. The hotter, denser bright areas are the embryonic clumps of galactic clusters.

"It's the earliest visible signal we can see from the big bang," said Tony Readhead, a professor of astronomy at Caltech who led the Cosmic Background Imager project.

The images confirm the basic recipe of ingredients that many cosmologists think make up the universe. About 5% is made of normal matter, the kind that makes up stars, Earth, even people. Thirty-five percent is the notoriously elusive dark matter, which has never been detected.

The rest of the universe is thought to be fleshed out by the even more mysterious dark energy, a little understood commodity created by theorists to explain the escalating clip at which the universe is expanding.

The findings also confirm leading theories of how the universe expanded and evolved after the big bang, often called the standard cosmological model. This model states that the universe grew from a tiny, subatomic region during a violent outward expansion known as inflation a microsecond after the big bang.

Guth, the father of inflationary theory, said he was stunned to see his theoretical calculations being verified with real-world evidence. "When I first started working on these calculations in 1982, we all considered it to be great fun," he said. "I never for a moment thought those calculations would be compared with actual observations."

The cosmic microwave background radiation was emitted when the universe was still a blistering trillions of degrees but had cooled enough that the dense, impenetrable fog of charged particles started to coalesce into atoms, letting light and radiation escape.

Over the 13.5 billion years or so since the big bang, the radiation cooled to just a few degrees above absolute zero (-459.67 degrees Fahrenheit). It is this faint afterglow of radiation that scientists now study with ultrasensitive telescopes and say is one of the most powerful tools to understand the early universe.

The existence of cosmic background radiation was first predicted in the 1940s, but the ripples were not detected until 1965.

Because earlier telescopes were not as powerful, scientists were unable to pick out any temperature differences. This was a problem. Without these differences, there was nothing that could evolve into coherent structure--no galaxies, suns, stars, planets. And no humans.

In 1992, a team at NASA and the Department of Energy's Lawrence Berkeley National Laboratory announced they had used a NASA satellite called the Cosmic Background Explorer Satellite, or COBE, to detect the first temperature differences in the radiation. Those results were immediately heralded as a missing link in cosmology and an important verification of big-bang theory.

The findings have since loosed a number of satellites, telescopes and high-altitude balloons to study the radiation in more detail and have spawned tens of thousands of scientific papers. "We didn't understand how important this would become," said John Mather, a NASA astronomer and co-leader of the COBE project.

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