Wednesday, October 21, 2009

a very lucky universe?

Guardian | In a desperate attempt to explain why Cern's Large Hadron Collider has suffered a series of mishaps preventing it from commencing its search for the elusive Higgs Boson particle, respectable physicists have suggested (apparently in all seriousness) that nature abhors the Higgs so much that ripples from the future are travelling back in time to stop the Switzerland-based particle accelerator working.

Reports of the emergence of these theories have prompted renewed contemplation of the "granny paradox", which some think debunks the very idea of time travel. In this scenario, a time traveller goes into the past and inadvertently causes the death of his/her granny, before the traveller's parents are born. So the traveller never goes back in time, so granny doesn't die – and, well, so on. I have a much simpler explanation for the collider's plight. Its failure is related to the existence of other universes, the "parallel worlds" beloved of science-fiction writers.

This theory suggests there are many – perhaps infinitely many – universes, some more or less like our own, some very different. This is not an idea confined to science fiction; it is respectable scientific speculation. Such universes are thought to exist in their own sets of space and time dimensions, and include worlds where key turning points in history, such as the Battle of Hastings, turned out differently from the way things happened in our world. The physicist Hugh Everett proved half a century ago that this "many worlds" idea is completely compatible with everything we know about the way the world works, and is a natural feature of quantum physics.