Parallel universes would seem to be the most unlikely prediction of relativity, but their proposal is just as fact-based as those dealing with black holes.

The idea of parallel universes was taken seriously after experiments with properties of light. Night exhibits wave-particle duality-it acts like both a particle and a wave. But even this odd characteristic did not account for the surprising results scientists noted in 'double slit tests'. A beam of light would be shined at a screen through another screen with two slits in it. When both slits were open, it seemed as if an electron would pass through both at the same time; and with one open, some areas of the screen would get more light then when both were open. While some of this could be attributed to particle-wave duality, in some cases it seemed almost as though the possibilities of what the light could do was affecting the outcome.

The only way for this to happen is for all the possiblities to exist at once. This idea is the backbone of the parallel universe theory-that all the possibilities for every action exist as an alternate universe. At the moment when an outcome is needed, they can overlap, or one of the separate universes will bend its solution.

Because there are an infinite number of possibilities, there is an infinite number of parallel universes, and therefore, an infinite number of you. A parallel universe for you oversleeping this morning, losing your homework, wearing different clothes... it goes on. For every interaction, there is a myriad of possibilites.

This all seems very far-fetched from Einstein's theory, but Einstein actually speculated and believed in parallel universes. He helped to discover the Einstein-Rosem Bridge-the area at the singularity of a rotating black hole where one can cross into a parallel universe.

Which is really the heart of the problem-reaching the singularity of a rotating black hole. But you'll have to read about black holes to find out why.