Imagine a world where dinosaurs hadn't become extinct, Germany had won World War II and you were born in an entirely different country.
These worlds could exist today in parallel universes, which constantly interact with each other, according to a group of US and Australian researchers.
It may sound like science fiction, but the new theory could resolve some of the irregularities in quantum mechanics that have baffled scientists for centuries.
The team from Griffiths University and the University of California suggest that rather than evolving independently, nearby worlds influence one another by a subtle force of repulsion.
They claim that such an interaction could explain everything that is bizarre about how particles operate on a microscopic scale.
Quantum mechanics is notoriously difficult to fathom, exhibiting weird phenomena which seem to violate the laws of cause and effect.
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