The concept of parallel universes has long been a staple of comic books and science fiction, but evidence for real ones has been lacking. However, some scientists now theorize that so-called a "Cold Spot" in space might be proof of the existence of the multiverse.
The cosmic microwave background refers to the residual energy left over from the big bang. This background energy pervades the universe and is uniform in distribution and temperature, but there's one spot that stands out. Darker and colder than the rest, this was long thought to be the result of a supervoid.
Some researchers disagree with the "supervoid" theory, stating that it is incompatible with the standard model of physics.
"The voids we have detected cannot explain the Cold Spot under standard cosmology," said Ruari Mackenzie from Durham University. "There is the possibility that some non-standard model could be proposed to link the two in the future but our data place powerful constraints on any attempt to do that."
The researchers were quick to point out that something as strange as the Cold Spot was unlikely to come about by random chance so they've offered a wide range of theories as to how it came to be.
"This means we can't entirely rule out that the Spot is caused by an unlikely fluctuation explained by the standard model," said Tom Shanks. "But if that isn't the answer, then there are more exotic explanations."
The most interesting of those theories is that the Cold Spot is the result of a collusion between our universe and another pocket universe which would prove the existence of multiverse theory.
"Perhaps the most exciting of these is that the Cold Spot was caused by a collision between our universe and another bubble universe," said Shanks. "If further, more detailed, analysis of CMB data proves this to be the case then the Cold Spot might be taken as the first evidence for the multiverse - and billions of other universes may exist like our own."
Shanks and Mackenzie are far from the only scientists to seriously consider the possibility of parallel universes. Stephen Hawking, for example, authored a paper in which he argues that black holes could serve as gateways to parallel universes.
Welcome To The Multiverse
The multiverse theory holds that there are an unknown number of parallel universes that exist alongside our own. Obviously, it is impossible to accurately speculate as to what these universes would be like though plenty of people have tried.
Sci-fi contains an entire subgenre dedicated to the idea of exploring worlds just like ours, save for one change. A common one, which inspired Amazon's hit show The Man In The High Castle, is the idea of the Axis powers winning World War II. Another famous trope is the idea of finding your evil twin in another universe.