Quantum Crunch

Is our universe about to be mangled?

* 17:43 23 February 2006
* NewScientist.com news service
* Maggie McKee

Our universe may one day be obliterated or assimilated by a larger universe, according to a controversial new analysis. The work suggests the parallel universes proposed by some quantum theorists may not actually be parallel but could interact – and with disastrous consequences.

Random quantum fluctuations mean the behaviour of particles and photons of light cannot be predicted exactly. The quantum equations that describe them contain a variety of different - and opposing - outcomes in their solution, such as a particular particle causing a bell to both ring and not ring in an experimental setup. Physicists then have to use an equation called the Born rule to calculate the probability of the bell ringing, and countless experiments have shown the rule works.

But researchers have long struggled to understand why a bell will ring – or not ring – in any given run of an experiment, since in theory it has the option of doing both. This conundrum, known as the quantum measurement problem, has led a small subset of physicists to argue that in fact the bell does do both - but that each possible outcome takes place in a different, parallel universe that pops into existence during the experiment.

"This is what the math suggests if you take it literally," says Robin Hanson of George Mason University in Fairfax, Virginia, US. But the idea that "every microsecond, the universe splits into a bunch more universes boggles the mind."