James Randerson in The Guardian:
The revolutionary study suggests that time did not begin with the big bang 14 billion years ago. This mammoth explosion which created all the matter we see around us, was just the most recent of many.
The standard big bang theory says the universe began with a massive explosion, but the new theory suggests it is a cyclic event that consists of repeating big bangs.
“People have inferred that time began then, but there really wasn’t any reason for that inference,” said Neil Turok, a theoretical physicist at the University of Cambridge, “What we are proposing is very radical. It’s saying there was time before the big bang.”
Under his theory, published today in the journal Science with Paul Steinhardt at Princeton University in New Jersey, the universe must be at least a trillion years old with many big bangs happening before our own. With each bang, the theory predicts that matter keeps on expanding and dissipating into infinite space before another horrendous blast of radiation and matter replenishes it. “I think it is much more likely to be far older than a trillion years though,” said Prof Turok. “There doesn’t have to be a beginning of time. According to our theory, the universe may be infinitely old and infinitely large.”