THE idea that other universes - as well as our own - lie within bubbles of space and time has received a boost. Studies of the low-temperature glow left from the Big Bang suggest that several of these bubble universes may have left marks on our own. This multiverse idea is popular in modern physics, but experimental tests have been hard to come by. The preliminary work, to be published in Physical Review D, will be firmed up using data from the Planck telescope. For now, the team has worked with seven years worth of data from the Wilkinson Microwave Anisotropy Probe, which measures in minute detail the cosmic microwave background (CMB) - the faint glow left from our Universes formation. The theory that invokes these bubble universes - a theory formally called eternal inflation - holds that such universes are popping into and out of existence and colliding all the time, with the space between them rapidly expanding - meaning that they are forever out of reach of one another. But Hiranya Peiris, a cosmologist at University College London, and her colleagues have now worked out that when these universes are created adjacent to our own, they may leave a characteristic pattern in the CMB. Id heard about this 'multiverse for years and years, and I never took it seriously because I thought its not testable, Dr Peiris told BBC News. I was just amazed by the idea that you can test for all these other universes out there - its just mind-blowing. Dr Peiris team first proposed these disc-shaped signatures in the CMB in a paper published in Physical Review Letters, and the new work fleshes out the idea, putting numbers to how many bubble universes we may be able to see now. Crucially, they used a computer program that looked for these discs automatically - reducing the chance that one of the collaborators would see the expected shape in the data when it was not in fact there. The program found four particular areas that look likely to be signatures of the bubble universes - where the bubbles were 10 times more likely than the standard theory to explain the variations that the team saw in the CMB. BBC