On this episode of Science to Save the World, Ryan O’Shea talks about the idea of multiple universes and possible interactions between them.
Marvel’s Doctor Strange in the Multiverse of Madness explores the potential of parallel universes, but this concept is more than fiction – many scientists treat multiverse theories seriously, and are actively trying to find evidence for their existence.
And there may be some. For example, the ANITA experiment, in which scientists at the South Pole sought to detect neutrinos coming from space, noticed something very odd. Some neutrinos were detected going the opposite direction, from Earth up into space. This led to a theory that this was evidence of a parallel universe in which time moved backwards. A more mundane explanation is that this can all be explained by reflections from underground snow and ice.
Then there’s the CMB Cold Spot, an area of unexpectedly low temperatures in one area of the Cosmic Microwave Background radiation, a remnant of our early universe. Many believe that this Cold Spot is the result of a supervoid – an area with a much lower density of matter in which the matter that is present loses energy and becomes noticeably cooler, thus explaining the cold spot. Others aren’t convinced, and the theory has been put forward that the Cold Spot is the result of our universe colliding with a parallel universe.
Those first two examples may be evidence for a multiverse, but they also have some normal possible explanations. This next one is the most famous, and I would say the weirdest. The double slit experiment has been repeated time and time again, and each time things get a little bit stranger. This experiment shows that photons, electrons, or even molecules can exist as a particle or a wave based on whether or not they are observed, and this has been used to support the many-worlds interpretation of quantum mechanics. In this scenario, the equipment used to determine which slit the photon went through becomes entangled with the particle, and a whole new universe is created in that moment in which the particle goes through either the left or right slit. You continue to exist in one of the universes, while a different version of you is in another.
Nothing is certain yet, but more work is being done. So while the Multiverse of Madness is pretty strange, reality isn’t that far behind it.