Scientists who believe our universe is just one of many have found a way to put their theory to the test. The "multiverse" theory holds that our universe is in a bubble of space and time drifting in a sea of other "bubble universes." Cosmologists say that the cosmic background radiation left over from the Big Bang shows tantalizing signs of collisions with other bubbles, the BBC reports. The European Space Agency's Planck space telescope is expected to provide data that will either back up the theory or refute it.
"The work represents an opportunity to test a theory that is truly mind-blowing: that we exist within a vast multiverse, where other universes are constantly popping into existence,” the lead researcher says. But even if the existence of bubble universes—where the laws of nature may be utterly different—is confirmed, it will be impossible to learn more about them, he warns. "It would be wonderful to be able to go outside our bubble, but it's not going to be possible," she says. (Read more multiverse stories.)