Today I’m starting a new series of articles for our blog where I will try to give you a brief explanation of various types of multiverse and to describe why whole this idea of multiverse seems to be very plausible for the physicists studying this stuff. It’s worth saying that these ideas are taken from Brian Greene’s book “The Hidden Reality” where much more detailed explanations can be found. My goal here is actually to convince you that the book is really worth reading. I’ll try to provide each new article once over two weeks or something like that, but if you can’t wait to get more information – I suggest you to read the book.
As you might guess, Brian Greene started with the notion of multiverse that seems to be very natural and very straightforward. I’m going to follow the sequence of various types of multiverse described in that book so the idea of my first article will also be very straightforward. However, for such a multiverse to come into existence we must assume that our Universe is infinite. If we do so, the notion of the so-called Patchwork Multiverse (or Quilted Multiverse) seems to be very natural.
As I’ve already mentioned, to take into account the notion of such a multiverse we must assume that the Universe itself is infinite. If one strongly believes that it is finite he or she (I’m not going to repeat this every time leaving it just as he, but this doesn’t mean that any abstract person I refer to is going to be a man, I will do it for the sake of not repeating “he or she” every time, so I must offer my apologies to the reader if it will look like I’m referring to a man in this case) might find these arguments not really convincing and the most striking evidence for a finite Universe might seem to come from a pretty much established Big Bang model. Certainly, one might argue that if the Big Bang was there and it started from an infinitesimally small and infinitely dense point of spacetime the Universe it produced must be finite even though enormously large.
However, the Big Bang model tells us nothing about whether our Universe is finite or infinite. The spacetime structure might have already existed before the Big Bang, being infinite and the Big Bang itself might have happened in every point of that infinite structure giving the birth of our Universe and countless other Universes at the same time.
What’s interesting about this is that such Universes wouldn’t be separated, instead they all would be one infinite Universe and in this sense the word Universe would mean exactly everything as humanity were supposed to think before the multiverse idea came into existence.
Okay, now let us turn to the Patchwork Multiverse idea. If you think about it, while the Universe is infinite in this model, the amount of various types of particles are going to be the same and all those particles would be governed by the same laws of physics. And since the amount of various types of particles is the same, the combinations of those particles are definitely finite, even though the amount of such combinations could be unimaginably vast.
That might pop up in your mind already that if we are talking about an infinite Universe and finite combinations of particles those combinations must repeat each other eventually though the exact copy might be found far beyond our observable Universe which is roughly 41 billion light-years in radius.
You can imagine a fly that happened to exist on the surface of the Earth. If we want to determine where this particular fly will appear in a month our laws of physics would certainly be insufficient to determine the exact location of the fly. Nevertheless, we can be absolutely sure that the fly won’t be able to leave the Earth since it can’t even possibly reach the sufficient speed to overcome the Earth’s gravity. And if we had, say, a trillion Earths we can be pretty confident that at least on some of them the fly would appear at exactly the same location.
This certainly means that if our Universe is infinite, there are countless copies of our planet in it: the infinite amount of Earth copies where your twins are sitting and reading this article having their doubts about such a notion, countless worlds where my English is much better and you don’t have to guess the meaning of my last sentence, countless worlds where I’ve died for some reason after writing this article, countless worlds where I became a King after writing this article, countless worlds with all the other possible fates of myself and yours as well.
Would you like to switch places with some of your counterparts? As for me, I wouldn’t like it for some reason.