“Every time there is an event at the quantum level – a radioactive atom decaying, for example, or a particle of light impinging on your retina – the universe is supposed to ‘split’ into different universes.
A motorist who has a near miss, for instance, might feel relieved at his lucky escape. But in a parallel universe, another version of the same driver will have been killed. Yet another universe will see the motorist recover after treatment in hospital. The number of alternative scenarios is endless.
In this way, the ‘many worlds’ interpretation of quantum mechanics allows a time traveller to alter the past without producing problems such as the notorious grandfather paradox.
But the ‘many worlds’ idea has been attacked, with one theoretician joking that it is ‘cheap on assumptions but expensive on universes’ and others that it is ‘repugnant to common sense.’
Now new research confirms Prof Deutsch’s ideas and suggests that Dr Everett, who was a Phd student at Princeton University when he came up with the theory, was on the right track.”