Grand Unified Theory

by : Aria Ratmandanu

      Physicists can run the expansion of the universe backwards. In this way, they can watch it get hotter as it gets smaller, just as the air in a bicycle pump heats up as it is compressed. But theory proposes that, at the big bang itself, the temperature was infinite. And infinities warn physicists that theories are flawed.

        At the moment, the theories which take us furthest back in time are the Grand Unified Theories. These GUTs are an attempt to show that three of the basic forces that govern the behaviour of all matter - the strong and weak nuclear forces and the electromagnetic force - are no more than facets of a single 'superforce. 

      Each force of nature arises from the exchange of a different messenger particle, or boson. The messenger transmits a force between two particles, just as a tennis ball transmits to a player the force of an opponent's shot. At high enough temperatures - such as those when the universe was 10^-35  seconds old ---- physicists believe the electromagnetic and strong and weak nuclear forces were identical, and mediated by a messenger dubbed the X-boson. 

       Physicists want to show that gravity, too, is a facet of the superforce. They suspect that gravity split apart from the other three forces at about 10^-43  seconds after the big bang. But before they can 'unify the four forces, they must describe gravity using quantum theory, which is hugely successful for describing the other forces. To say that physicists are finding this difficult is an understatement.

       When they have their unified theory, physicists believe that they will be able to probe right back to the moment of creation and explain how the universe popped suddenly into existence from nothing 13.82 billion years ago.