"Stephen Hawking has said: "We should look for evidence of a collision with another universe in our distant Past." Some experts believe that what we call the universe may only be one of many. Is there any conceivable way that we could ever detect and study other universes if they exist? Is it even falsifiable? This was a key question Hawking was was asked in an interview with the BBC. "Our best bet for a theory of everything is M-theory --an extension of string theory," Hawking continued. "One prediction of M-theory is that there are many different universes, with different values for the physical constants. This might explain why the physical constants we measure seem fine-tuned to the values required for life to exist." It is no surprise that we observe the physical constants to be finely-tuned. If they weren't, we wouldn't be here to observe them. One way of testing the theory that we may be one of many universes would be to look for features in the cosmic microwave background radiation (CMB) which would indicate the collision of another universe with ours in the distant past. The circular patterns within the cosmic microwave background shown above suggest that space and time did not come into being at the Big Bang but that our universe in fact continually cycles through a series of "aeons," according to University of Oxford theoretical physicist Roger Penrose, who says that data collected by NASA's WMAP satellite supports his idea of "conformal cyclic cosmology". (...) - Amira

"[Penrose] does not believe that space and time came into existence at the moment of the Big Bang but that the Big Bang was in fact just one in a series of many, with each big bang marking the start of a new "aeon" in the history of the universe." The core concept in Penrose's theory is the idea that in the very distant future the universe will in one sense become very similar to how it was at the Big Bang. Penrose says that "at these points the shape, or geometry, of the universe was and will be very smooth, in contrast to its current very jagged form. This continuity of shape, he maintains, will allow a transition from the end of the current aeon, when the universe will have expanded to become infinitely large, to the start of the next, when it once again becomes infinitesimally small and explodes outwards from the next big bang. Crucially, he says, the entropy at this transition stage will be extremely low, because black holes, which destroy all information that they suck in, evaporate as the universe expands and in so doing remove entropy from the universe." - Amira