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Big bounce theory of universe makes a comeback

The universe may have started not with a bang but a bounce, say scientists.

A new study suggests the cosmos may have exploded back into being after previously collapsing in on itself.

The "Big Bounce" idea was first suggested in 1922 but has largely been discounted. Scientists thought a universe contracting under the force of gravity into a "Big Crunch" would inevitably destroy itself completely, with no hope of resurrection.

Now the world of quantum mechanics, which describes the strange behaviour of sub-atomic particles, has come to the rescue of the Big Bounce theory.

The new concept hinges on the fact that, in the beginning, everything was very, very small.

Cosmologists know that the universe today is expanding outwards, like an inflating balloon.

Around 14 billion years ago, it is thought to have abruptly burst into existence from an unimaginably hot and dense point far smaller than an atom - the so-called "Big Bang".

The Big Bounce scientists point out that the laws of quantum mechanics, rather than cosmological scale physics, would have governed the tiny infant universe.

Quantum effects could have prevented a contracting collapsing universe from destroying itself in a "Big Crunch", they say.

According to the theory, the universe may have switched from a contracting to an expanding state without collapsing completely.

Dr Steffen Gielen, from Imperial College London, co-author of a paper outlining the theory in the journal Physical Review Letters, said: "Quantum mechanics saves us when things break down.

"It saves electrons from falling in and destroying atoms, so maybe it could also save the early universe from such violent beginnings and endings as the Big Bang and Big Crunch."

He and Canadian colleague Dr Neil Turok, director of the Perimeter Institute for Theoretical Physics, built a mathematical model showing how a Big Bounce universe might evolve.

They are now investigating how the model can explain the formation of galaxies out of the furnace of the early universe.

"Our model's ability to give a possible solution to the problem of the Big Bang opens the way to new explanations for the formation of the universe," said Dr Gielen.

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