Finding Warps in the Universe

BIG BANG

May 31, 1992|By DOUGLAS BIRCH | DOUGLAS BIRCH,Douglas Birch covers science for The Baltimore Sun.

"It is the discovery of the century, if not all time."

-- Stephen William Hawking, physicist

Not many scientific discoveries make "Nightline," the "Today" show and People magazine.

But then, the April 23 announcement by Dr. George Smoot that NASA's COBE satellite had found hot and cold regions in faint heat still left over from the moment the universe was created -- the Big Bang -- was no ordinary discovery.

What Dr. Smoot, who works at the Lawrence Berkeley Laboratory in California and the Goddard Space Flight Center in Greenbelt, and his colleagues created was a snapshot of the universe a relatively short time after creation -- a snapshot that also can be viewed as the rough blueprint from which the present universe evolved.

Even as popular interest in the discovery mushroomed, though, some scientists and scholarly journals sounded notes of caution. Was the data reliable? some wondered. Was it really the Earth-shaking discovery some scientists claimed? others asked.

Was the science, many wondered, being lost in the hype?

In the the Big Bang aftershock of 1992, here are some questions and tentative answers about what the discovery means.

What is the Big Bang?

The Big Bang theory says the universe began about 15 billion years ago with an explosion from a corpuscle of energy too small for the most powerful microscopes to detect.

One version of the theory holds that this energy popped into existence from sheer nothingness, like one of the beaded bubbles winking at the brim of your beer glass, to parphrase John Keats.

As the universe lost some of its initial heat in its opening seconds, energy became particles. Around the three minute mark, protons and neutrons began to stick together to form atomic nuclei. About 100,000 years later, the universe cooled to the point where electrons could begin to orbit nuclei without getting knocked off.

This hot soup eventually became everything we see around us -- our galaxy, the planets, the Earth, the trees, parking meters, mountain ranges, shopping malls, ourselves.

This was no ordinary explosion. It was not as though a speck of dust floating in the vast lonely vacuum of space suddenly detonated like a huge hydrogen bomb. Before the Big Bang, there was that speck contained not only all matter, but space-time itself. There was nothing outside the speck -- not even the vacuum of space.

When scientists search for the afterglow of this cataclysm, they can look anywhere in the sky because it did not happen at some specific point.

It happened everywhere all at once, because all matter and space were compressed into a point.

* What is COBE, what was it looking for and what did it find?

NASA's Cosmic Background Explorer satellite, launched in November 1989, carries an instrument package called the Differential Microwave Radiometers, a kind of sophisticated bundle of six thermometers.

The thermometers were built to detect tiny differences in the intensity or temperature of microwave radiation glowing in different regions of the sky. These variations had long been predicted by the Big Bang theory, but never found.

As COBE circled the Earth's poles 625 miles up, NASA researchers pointed its radiometers at every region of space, taking hundreds of millions of readings.

By filtering out microwave radiation from local galaxies, researchers concentrated on those from the deepest part of the sky, generated when the universe was a mere 300,000 years old.

The average or background temperature of the universe is about -455 degrees Farenheit, or 5 degrees above absolute zero.

COBE scientists found, for the first time, variations in this background temperature of less than 1 part in 100,000. Using this data, they produced a map of the sky showing the cold and not-so-cold blotches.

"These small variations are the imprints of tiny ripples in the fabric of space-time put there by the primeval explosion process," Dr. Smoot explained. "Over billions of years, the smaller of these ripples have grown into galaxies, clusters of galaxies and the great voids in space."

* What difference does 1/100,000th of a degree make?

Lots. Those variations are crucial to scientists trying to understand how the smoothness of the initial Big Bang became the very lumpy universe we see today, with matter stuck together in some places in galaxies, clusters of galaxies and super clusters of galaxies -- while in other places there are gaping voids where no stars shine.

* Was the COBE discovery a surprise?

Not at all. But it was a big relief.

"This was precisely what was predicted as the simplest way to generate and understand the origins of structure in the universe," said Alex Szalay, a theoretical physicist with Johns Hopkins University. "And it's beautiful, it matches that."

Until COBE, the residual heat from the Big Bang spread out across the sky seemed uncannily uniform. That implied a uniform Big Bang. And a totally smooth Big Bang would have produced a featureless universe, like a huge bowl of oatmeal without lumps.

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