The last paper submitted by Stephen Hawking before death. Here is what it says.

There was a time we thought our planet was unique. Later we realised it was just another planet among many other planets in the solar system. Then solar system was thought to be unique, then our Galaxy and so on. At the moment we at least think that our universe is unique, after all it’s ‘uni-verse’. But late Professor Stephen Hawking’s last paper ,which he submitted ten days before his death to the journal of High energy physics is hinting at the possibility of the existence of a multiverse.

see also: This is the reason why Stephen Hawking could not get a Nobel Prize 

Prof Hawkings was working along with Prof Thomas Hertog at KU Leuven in Belgium who is funded by the European Research Council. The final paper submitted was a work of 20 years of collaboration with Hertog. Hertog said that the theory they developed allowed the existence of multiple universes, but they weren’t happy with the fact that they couldn’t say more about it. In the 1980s, Hawking along with US physicist James Hartle developed a new idea of the beginning of universe – quantum mechanics which tried to explain how the universe came out of nothing. But it also left the possibility that ours could have been one among the many universes that arose in that fashion.

So What would the other universes look like ? Well it may have a completely different laws of physics, it may have individuals like us, may be the dinosaur era is still running there. There might be universes which are completely empty. There exists a possibility of infinite number of galaxies with infinite number of composition and we cannot predict what kind of a universe have we found ourselves in.. proof Hertog says moving from one universe to another is not a possibility, if they exist. So if you have seen the film Butterfly Effect, well that ain’t gonna happen for you, according to Hawking.