Is There Another 'You' Out There In A Parallel Universe?

One of the most exciting and enticing topics to speculate about is the idea that our reality — our Universe the way it is and the way we experience it — might not be the only version of events out there. Perhaps there are other Universes, perhaps even with different versions of ourselves, different histories and alternate outcomes, than our own. When it comes to physics, this is one of the most exciting possibilities of all.

The Universe, as far as the most powerful telescopes can see (even in theory), is vast, huge and massive. Including photons and neutrinos, it contains some 10^90 particles, clumped and clustered together into hundreds-of-billions-to-trillions of galaxies. Each one of those galaxies comes with around a trillion stars inside (on average), and they’re strewn across the cosmos in a sphere some 92 billion light years in diameter, from our perspective. But, despite what our intuition might tell us, that doesn’t mean we’re at the center of a finite Universe. In fact, the evidence indicates something quite to the contrary.

The reason the Universe appears finite in size to us — the reason we can’t see anything that’s more than a specific distance away — isn’t because the Universe is actually finite in size, but is rather because the Universe has only existed in its present state for a finite amount of time. If you learn nothing else about the Big Bang, it should be this: the Universe was not constant in space or in time, but rather has evolved from a more uniform, hotter, denser state to a clumpier, cooler and more diffuse state today.

But this in no way means that there isn’t more Universe out there beyond the portion that’s accessible to us. In fact, from both observational and theoretical points-of-view, we have every reason to believe there’s plenty more, and perhaps even infinitely more.

The multiverse idea states that there are infinite numbers of Universes like our own, and infinite ones with differences. Image credit: flickr user Lee Davy, via https://www.flickr.com/photos/chingster23/11937781733. (CC BY 2.0)

In other worlds, would it be possible that there’s a Universe out there where everything happened exactly as it did in this one, except you did one tiny thing different, and hence had your life turn out incredibly different as a result?