As if our Universe is not gigantic enough all by itself, for about 15 years now scientists have been getting more and more excited by the notion that there are multiple Universes.
It is estimated that our galaxy, the Milky Way, contains 400 billion suns and three quarters of them are bigger than our sun. As if that is not enough it is estimated that there are 300 billion galaxies in the known Universe. That means there are about 400 billion by 300 billion suns in the known Universe.
As I mentioned there have been theories of “layered Universes” for some time. My favourite theory is where the multiple Universes are layered one on top of the other like sheets of paper in a stack.
Another view popular with makers of science fiction movies is that the multiple Universes all occupy the same Universal-space, so to speak. In such movies there is usually some special event that occurs that causes people to flick between the different Universes.
Much like the layers of paper theory another model has each of the Universes stacked up like plates, one of top of the other. Or like long-player vinyl records, for those that even know what a long-player vinyl record looks like.
Some groups of scientists are now so sure that there are multiple Universes that they now refer to our Universe as U1, or, as a search of the Web will tell you, it is sometimes referred to as the “grey” Universe. Presumably as they find the other Universes they will get assigned colours as well. Pity they didn’t pick a better colour than grey for the colour of our Universe—oh well.
The latest theory, summarised in this article at the Technology Review site, puts forward the view that the multiple Universes are like Russian Dolls, or layers on an onion. Each Universe is within the Universe around it but at some points the Universes bump into each other causes “cosmic bruising”.
It is all theory with only the slightest touch of real data sprinkled in, but it is kind of exciting, and with each passing year the evidence for multiple Universes piles up, even if the pile is only about as high as a sewing thimble at this stage.