Testable Theories of the Multiverse
But what if the concept of the multiverse were testable? According to Ranga-Ram Chary, Project Scientist and Project Manager of the U.S. Planck Data Center at Caltech, it just might be. Chary published a study in 2015 in the Astrophysical Journal detailing strange abnormalities in the cosmic microwave background (CMB)—the radiation leftover after the Big Bang. These abnormalities, found when analyzing data from the Planck telescope, could be evidence of “bruising” that occurs when one universe bumps up against another.
“Think of it as bubbles in a soda bottle,” Chary told Astronomy. “Each bubble is a Universe. If the bubbles were rare, they would never collide and we'd never know the existence of the other Universe. In that case, search for a multiverse is just fiction. If however, they are not rare, they may collide and we can see the imprint in the CMB.”
Evidence of those imprints might be found in the data mentioned in Chary’s 2015 study. However, it’s possible that the abnormalities observed are merely an anomaly, or due to contamination from the interstellar medium (the matter between stars), so Chary stressed that further research is required. Still, Chary’s ideas about colliding universes would bring the multiverse into the realm of a testable hypothesis, and out of the realm of pure speculation.
In fact, Chary noted that if the multiverse was purely a philosophical question, it shouldn’t be studied. For instance, if the proposed “bubbles” were too far apart, and scientists would not be able to obtain relevant data to confirm their existence, Chary says that scientists should not study it. “The nature of science is, take observational data, test a hypothesis, and try to interpret the data in the hypothesis,” he stressed. “Here, we’re trying to get absolute truth here. We would like to know why our universe is the way it is. If I can’t take data to answer that question, then I should be doing something else.”
The bottom line? Most scientists seem to agree that rigorous science should involve falsifiable hypotheses—ones that can be confirmed or disproved by data. That standard is no different for concepts like the multiverse, and work like Chary’s presents one model of multiverse theory that is testable, and thus verifiable.
Still, by nature, science is always pushing the boundaries of our knowledge. “In some sense, there’s a frontier,” James Bullock, Professor of Physics and Astronomy at UC Irvine, told Astronomy. “And there’s going to always be this fuzzy frontier on the edge of knowledge where things are not locked down. And that doesn’t mean those pursuits aren’t worthy. That’s where the crux of the issue lies: we want to be honest about the things we understand and don’t understand.”