London, Feb. 9: Professor Hawking, we have a problem. Nasa, the American space agency, is expected to announce this week that it has proved the existence of “dark energy”, a cosmic force that counteracts gravity and will keep the universe expanding forever.
The announcement will effectively demolish the theory that life will be wiped out in a “Big Crunch” when the universe collapses, and should end decades of academic dispute over the forces at work on the universe.
In the past, scientists ranging from Prof Stephen Hawking, the Cambridge University physicist, to Albert Einstein, have argued that the universe eventually will stop expanding and then implode under the force of gravity, destroying all life.
Nasa’s research indicates, however, that this analysis is wrong. Using a satellite — the Microwave Anistropy Probe (Map) — which has spent the past year peering into deep space, Nasa has discovered a pattern of “hot spots” which, it says, proves that the universe is accelerating.
This means that “dark energy” — the only force that could cause this acceleration — does exist, and that the universe is expanding too quickly to collapse under gravity, ruling out the possibility of a “Big Crunch”.
Prof Anthony Lasenby, an astrophysicist at Cambridge University, said the announcement would transform our view of the universe. “It will be an epoch-making event,” he said.
Another scientist explained: “It is like throwing a ball in the air. If gravity were the only force at work, the ball would eventually slow down and then start to fall back. What this shows is that the ball is not slowing down but is in fact accelerating away.”
The Nasa discovery is understood to be one of the most significant in the history of cosmology and, coming only days after the loss of the space shuttle Columbia, will provide a timely reminder of the value of the agency’s scientific work.
The behaviour of the universe is a subject that has troubled some of the greatest minds in science.
In 1917, to balance the equations in his General Theory of Relativity, Einstein argued that an unknown force — which he labelled the “cosmological constant” — was counteracting gravity and keeping the universe a constant size. In the wake of subsequent astronomical evidence that the universe was expanding, however, he abandoned this idea, calling it his greatest mistake.
The new data will show that Einstein’s attempt to fiddle his equations using this “cosmological constant” may have been right, but for entirely the wrong reasons.
In his 1998 bestseller A Brief History of Time, Prof Hawking claimed that the universe would eventually implode.
This assessment was challenged in 1997 when, after observations from ground-based telescopes, astronomers began to argue that gravity was counteracted by a “dark energy” that was causing the universe to expand at an ever-increasing rate.
Nasa’s study, however, the most detailed of the whole sky, is poised to settle the controversy. It uses measurements of the heat left over from the Big Bang, in which the universe was born 14 billion years ago, to demonstrate that the universe is expanding rapidly and is safe from collapse.
Prof Hawking remained undaunted by the Nasa findings, saying that he had continued working on his theories and had discovered that they were “quite compatible with the universe expanding forever” and the existence of dark energy.
Although Nasa’s discovery means that the universe will go on forever, the same is not true for human life. As the universe expands, all the energy needed to keep the stars and galaxies alight will be used up.
What will remain is a universe full of black holes, which after trillions of years, will explode to leave nothing but dark energy.
The Daily Telegraph