One-force theory 'coming soon'

PHYSICIST, Stephen Hawking, this week gave a "fifty-fifty" chance of researchers finding, within the next 20 years, a single theory to explain the relationship between all the fundamental forces of nature.

During a lecture at Cambridge University's Cavendish Laboratory in celebration of J. J. Thomson's discovery of the electron there, 100 years ago, Professor Hawking said that much would depend on researchers gaining a much better understanding of gravity, one of the fundamental forces, the others being the strong and weak nuclear forces and electromagnetism. The electron was the first elementary particle to be discovered.

Professor Hawking, famous for his theories on black holes in space, said: "The progress that has been made in unifying gravity with the other forces has been entirely theoretical. This has led to charges from some people that physics is dead because it has become just like a mathematical game, unrelated to experiment. But I don't agree."

The hunt for a unified field theory to explain the four forces, in terms of a single unified force began with Albert Einstein. Since then physicists have demonstrated the link between the weak and electromagnetic forces. They are now attempting to develop the grand unified theory (Gut) which combines the strong nuclear force with electromagnetism and the weak force.

Professor Hawking, Lucasian professor of mathematics at Cambridge, said there were several candidate "Guts" but that it was difficult to distinguish between them by experiment because most of the differences occurred only at very high energy, far beyond what can be produced in any particle accelerator on Earth.

While low energy experiments are helping to eliminate some of the "Guts", a major objection to these theories has been that they do not incorporate gravity.

Much hope is now being placed on the concepts called "supersymmetry" and "supergravity" to enable all the forces to be unified. Professor Hawking believes supersymmetry will be "absolutely fundamental" to any complete uni-fied theory. He hopes the Large Hadron Collider, the particle smashing machine being built by the particle physics laboratory Cern in Geneva, will confirm the existence of supersymmetry.