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Physicist tackles future of life, universe and everything
By KEVIN FRYLING
Reporter Staff Writer
A UB physicist told an audience yesterday that the fate of life in the far-off future seems to hinge on the nature of mysterious forces that currently are only vaguely understood by the world's scientific community.
William H. Kinney, assistant professor in the Department of Physics, College of Arts and Sciences, said during a UBThisSummer lecture entitled "The End of the Universe and the Future of Life" that the discovery of "dark energy" nine years ago created a radical shift in the scientific conception of both the beginning and the end of the universe.
"The expansion of the universe is not slowing down—it's speeding up," he said. "This was a big shock...Something is pushing the galaxies apart, rather than pulling them together."
Physicists refer to this force as "dark energy," he said, noting experts estimate that 75 percent of the entire mass of the universe is comprised of this unknown force or substance.
These conclusions clash with the previous model of the universe in which momentum from the "big bang" decreases over time and the observable universe increases in size, he said. The exact opposite is true in the new model, he said, in which dark energy creates infinite expansion and the observable universe decreases so that our place in the night sky is reduced to a "dark and static corner" in about 100 billion years.
"In an accelerating universe," he said, "we see less infinite space rather than more of it."
He explained that the bounds of the observable universe shrink as the space between objects accelerate and expand as the spaces close because no light from objects outside a range of 13.7 billion light years—the time of the birth of the universe—has enough time to reach the Earth.
Since the observable universe is finite, he added, even the vast resources of the universe are limited on an infinite time scale.
He pointed out that the Sun is projected to turn supernova and consume the Earth in 5 billion years and noted that physicists calculate that the formation of new stars will crease in about 1 trillion years and that the last stars will burn out in about 100 trillion years.
"In order to survive, life must change radically," said Kinney. "We have to talk about evolving beyond Earth-like forms."
Based on the premise that the most basic feature of life is its unique ability to reproduce—as well as taking inspiration from the theoretical physicist Freeman Dyson—Kinney concluded a theoretician might definite "life" as information and replication as computation.
So the question is: "Can a computer run forever in an expanding universe?" The short answer, he said, seems to be "no."
The problem hinges in part on calculations related to the second law of thermodynamics, he explained, which reveal that no theoretical computer could run forever in a universe that never stops cooling and expanding. But a computer could operate forever in a universe whose the expansion is slowing down, he added.
If physicists discover that the universe's total amount of dark energy decrease over time, he said, then expansion of the universe might slow and life in the form of replicating information could continue forever. If the mysterious forces pulling the universe apart remain unchanged or increase in mass, however, then life cannot survive on an infinite time scale.
"But even if our computer can run forever," Kinney added, "it only has a finite amount of memory available." The result? "Every thought is destined to be forgotten," he said, "and then rediscovered."