Like many parents, William Unruh occasionally takes his young son outside at night to gaze at the stars and to look for such constellations as the Big Dipper and Orion. And like most parents, the 46-year-old Vancouver resident acknowledges that he can identify only a few constellations without the aid of a guide. But for Unruh, the night sky is more than a passing interest. It is his life’s work. Unruh, a physicist and cosmologist at the University of British Columbia, is one of about a dozen Canadian scientists dedicated to studying the structure and origins of the universe. Last week, Canada’s cosmologists quietly celebrated the announcement that American scientists had developed space images illustrating the way in which a cosmic explosion may have set in motion the building of the universe about 15 billion years ago. Said Unruh: “It really firms up the models we have of how the universe developed.”
While astronomers study the behavior of specific pieces of the universe, cosmologists attempt to understand how the whole universe evolved.
And while astronomers can usually collect firm measurements to test their theories, cosmology is often a theoretical science. That was one reason why the Washington announcement of the new findings was greeted with so much enthusiasm. Said James Peebles, 57, a Canadian-born physicist who teaches at Princeton University in New Jersey: “It gives us a rock to stand on, and that’s difficult to do in cosmology.”
Explosion: Until the early 1920s, most scientists claimed that the universe was a static collection of stars, galaxies and other celestial objects. But as scientists began to absorb the theories of Albert Einstein, a few physicists, mathematicians and astronomers developed new models of the universe. In 1922, Russian mathematician Aleksandr Friedmann first argued that the universe may have been created by an explosion, and could still be expanding. Five years later, Belgian priest and astronomer Georges Lemaître developed a similar theory.
By the end of the 1920s, American astronomer Edwin Hubble had made a series of stunning discoveries that supported the theoretical work of Friedmann and Lemaître. Hubble first discovered that other galaxies existed outside
the Milky Way, the enormous system of stars of which Earth and the sun are a part. He then found that the individual galaxies are moving apart and concluded that the universe is expanding.
The next major breakthrough in what had become the emerging science of cosmology occurred almost 20 years later. In 1948, Russian-American scientist George Gamow developed a more elaborate theory about the explosion that triggered the creation of the universe, and it became known as the Big Bang. Gamow also speculated that relics of that immense cosmic explosion, in the form of light energy, or radiation, should still be travelling through the universe.
A quarter of a century later, Gamow was proven correct. During the mid-1960s, two scientists named Amo Penzias and Robert Wilson were testing a satellite receiving device
at a Bell Telephone laboratory. Coincidentally, about 50 km away at Princeton, a team of scientists that included cosmologist Peebles had begun an experiment aimed at finding Gamow’s radiation relics. Peebles said that the leader of the Princeton team, Robert Dicke, received a telephone call one day from the Bell scientists. They complained that their satellite receiver was picking up strange noises, which they could not identify. Peebles said that Dicke realized immediately that the noises came from radiation left over from the Big Bang. He put the telephone down, turned to his colleagues and said: “Fellows, we’ve been scooped.”
Waves: Since then, cosmologists have designed dozens of experiments aimed at analysing the reverberating waves of energy now known as cosmic background radiation. Scientists have also been looking at the universe from other angles. Peebles said that he is trying to unravel the mysteries of the universe by studying the size, location and distribution of galaxies. He said that he has relied on the pioneering work of two American scientists, Donald Shane and Carl Wirtanen, who in the 1950s photographed and mapped « the one million largest galaxies that ~ can be observed through telescopes. ^ During the past five years, three teams of British scientists have photographed and mapped another two million galaxies, all of them visible from the Southern Hemisphere.
To a cosmologist, cosmic background radiation represents the earliest information available about the formation of the universe. Peebles said that the galaxies represent the most up-to-date information. Even though hard scientific evidence has been found to provide some clues about the origins and the current status of the universe, most cosmologists acknowledge that they have only begun to explore a vast and perplexing subject. “A lot of the stuff we do addresses the most fundamental issues—questions about time and why we have time—that have philosophical implications,” said Unruh. “What has always amazed me is that our society is willing and able to support a few people doing this. I’m happy to be one of them.”
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