Physicists at the University College London, the Imperial College London and the Perimeter Institute for Theoretical Physics in Canada are looking for evidence that our universe has collided with other parallel universes. Yep, you read that right. Believe it or not, the theory of parallel universes has a place in mainstream physics, and a lot of researchers have spent significant time and energy developing the math to support it.

The theory comes in many forms. For example, the “Many Worlds Theory” from quantum mechanics essentially says that there’s a universe for every outcome of a situation, meaning there’s an incomprehensibly large number of alternate universes out there. There’s also the theory of bubble universes, which says that our universe is just one of many bubble universes that sprang out of the “false vacuum” to form a vast and expanding multiverse.

Brian Greene of Columbia University, a string theorist and author of The Elegant Universe, discussed the multiverse on NPR’s Fresh Air earlier this year. A recording of the entire 34-minute interview is at the bottom of the page, but here’s a short excerpt where Greene explains why he and many others take the theory of the multiverse seriously:

“The wonderful thing about the subject is that there’s not one monolithic notion of what a multiverse would be. As we have studied a whole variety of different areas of physics from relativity, quantum mechanics, cosmology, unified physics, it seems to be the case that whenever we follow the mathematics of these deep theories sufficiently far, we bump into one or another variety of the parallel universe idea, and to me what makes it so compelling is it’s not that we physicists are sitting at our desks saying “What kind of crazy idea can we introduce into science now?” It’s not like that at all. What we’re doing is sitting at our desks trying to do what we always do, which is trying to understand the universe, come up with theories that can describe our observations, our data, and when we follow those theories far enough, we come across some version that our universe is one of many.”

In a first attempt to find observational evidence of the multiverse, the team from London and Canada is using a computer algorithm to survey the cosmic microwave background (CMB) radiation left over from the Big Bang in search of disk-like patterns where our bubble may have collided with other bubbles. The CMB data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) hasn’t given them enough information to either confirm or rule out any collisions, but new data (available to the public in 2013) from the European Space Agency’s Planck satellite will help them further their search.

Cosmologist Hiranya Peiris of the University College London expressed her excitement about the project to the BBC:

“I’d heard about this ‘multiverse’ for years and years, and I never took it seriously because I thought it’s not testable,” she said. “I was just amazed by the idea that you can test for all these other universes out there — it’s just mind-blowing.”

Greene said in his interview with NPR that another source of observational evidence of the multiverse could be the Large Hadron Collider in Switzerland. String theory predicts that each universe is on its own “membrane,” and according to Greene, we can think of the multiverse as a cosmic loaf of bread where each slice is a separate universe. When scientists at the LHC smash protons into each other at unbelievable speeds, he said, it’s possible that remnants of the collisions could spin off of our slice of bread, leaving less energy after the collision than before it, which would otherwise be impossible according to the law of conservation of energy.

For most of our everday lives, it seem like evidence of the multiverse wouldn’t change things inside this bubble too much. We’ll never be able to explore other universes that may or may not even have the same laws of physics that we do. I know science has a reputation for making the impossible possible, but I think this impossibility is pretty definite. Discovering parallel universes would, however, rock the world of physics and could impact modern religion — if other worlds exist (perhaps even some that are identical to our own), a lot of people might have to reevaluate the role of their god(s) in all of this.

For now though, the multiverse will probably remain in the imaginations of science fiction fans and the minds of scientists, but it’s always fun to think about the “what if’s”….

Photos: Pawel, Flickr, CC and Undertow851, Flickr, CC