Is this considered to be something plausible or is it another series of Ben 10 cartoons?
Things are a lot more serious than that.
The multiverse is a theoretical framework in modern cosmology (and high energy physics) which presents the idea that there exist a vast array of potential universes which are actually manifest in some way.
One application of the multiverse in modern discourse is a means of invoking the anthropic principle to explain the finely tuned parameters of our own universe without recourse to the need of an intelligent designer.
As the argument goes, since we are here we know that the region of the multiverse in which we exist must be one of the regions that has the parameters to allow us to exist.
Supporting the theory
There are generally 5 types of multiverse that may actually exist:
Daughter Universes – Quantum mechanics describes the universe in terms of probabilities. In the quantum world, all possible outcomes of a choice or situation not only can occur, but do occur. At every branch point, a new universe is created.
Mathematical universes. Another possible avenue is exploring mathematical universes, which, simply put, explain that the structure of mathematics may change depending in which universe you reside.
Parallel Universes – According to this multiverse theory, the universe we perceive isn’t all there is. There are additional dimensions beyond the three spatial dimensions we perceive, plus time. Other three-dimensional “branes” may co-exist in higher-dimension space, thus acting as parallel universes.
Bubble universes. Another theory for multiple universes comes from “eternal inflation.” Based on research from Tufts University cosmologist Alexander Vilenkin, when looking at space-time as a whole, some areas of space stop inflating like the Big Bang inflated our own universe. Others, however, will keep getting larger. So if we picture our own universe as a bubble, it is sitting in a network of bubble universes of space. What’s interesting about this theory is the other universes could have very different laws of physics than our own, since they are not linked.
Infinite universes. We don’t know what the shape of space-time is exactly. One prominent theory is that it is flat and goes on forever. This would present the possibility of many universes being out there. But with that topic in mind, it’s possible that universes can start repeating themselves. That’s because particles can only be put together in so many ways. More about that in a moment.
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