The parallel worlds constantly influence one another, researchers claim. This is because, instead of a collapse in which quantum particles 'choose' to occupy one state or another, they in fact occupy both, simultaneously. The theory could resolve some of the irregularities in quantum mechanics. It states some worlds are almost identical to ours, but most are different. Theory may even create possibility of one day testing for these worlds. 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. 'The idea of parallel universes in quantum mechanics has been around since 1957,' said Howard Wiseman, a professor in Physics at Griffith University. In the well-known Many-Worlds Interpretation, each universe branches into a bunch of new universes every time a quantum measurement is made. The universe is a hologram and everything you can see - including this article and the device you are reading it on - is a mere projection. This is according to a controversial model proposed in 1997 by theoretical physicist Juan Maldacena. Until now the bizarre theory had never been tested, but recent mathematical models suggest that the mind-boggling principle could be true. According to the theory, gravity in the universe comes from thin, vibrating strings. These strings are holograms of events that take place in a simpler, flatter cosmos. Professor Maldacena's model suggests that the universe exists in nine dimensions of space, and one of time. In December, Japanese researchers attempted to tackle this problem by providing mathematical evidence that the holographic principle might be correct. The holographic principle suggests that, like the security chip on a credit card for example, there is a two-dimensional surface that contains all the information needed to describe a three-dimensional object - which in this case is our universe. In essence, the principle claims that data containing a description of a volume of space - such as a human or a comet - could be hidden in a region of this flattened, 'real' version of the universe. In a black hole, for instance, all the objects that ever fall into it would be entirely contained in surface fluctuations. This means that the objects would be stored almost as 'memory' or fragment of data rather than a physical object in existence.