Parallel universes, also known as meta-universes or multiverses, are a group of theoretical twin universes that coexist at the same time as our own. They are said to be simple variations of our reality, all running at the same time in different realities. These universes are not uniquely confined to the science fiction realm anymore; philosophy, physics, and even theology have theories about why multiverses exist and how they work. Parallel universes have often been used in fiction and TV programs as an explanation for strange phenomena.
Quantum mechanics, the science that looks for explanations to phenomena that cannot be explained by the regular laws of physics and science, has been studying parallel universes since 1956. American physicist Hugh Everett first formulated the idea of their existence to explain the theory that every possible outcome of every choice we have actually does happen. While in this universe you may choose path A, an alternate you will choose path B in a parallel universe.
Where and how parallel universes exist is actually the most heated source of debate. Some say meta-universes exist close to us. So close, in fact, that ghosts may be nothing more than people from alternate universes somehow slipping into our reality. Others postulate that these universes are infinitely far, way beyond the farthest galaxies. A third theory is that parallel universes exist in different dimensions, either lower or higher than the four-dimension world we live in.
While the idea of parallel universes may seem incredible, more and more scientists are buying into the idea of a multitude of universes coexisting barely millimeters away. A disturbing new theory currently being researched in several high-profile universities holds that the Big Bang may not have been the actual beginning of the universe. In fact, some scientists are now claiming that the big explosion we see as the origin of our life could actually be the result of two universes colliding, thus generating a new one. This revolutionary theory has been taken seriously by quantum mechanic scientists and is now the source of heated debate across the world.