In Brief
  • There are some who say the Universe is finite and others who claim it to be infinite.
  • If the Universe is, indeed, infinite, there might be more of you than

Two possibilities exist: either the Universe is finite and has a size, or it’s infinite and goes on forever. Both possibilities have mind-bending implications.

In previous episode of Guide to Space, I discussed: “how big is our Universe.” I said it all depends on whether the Universe is finite or infinite. I mumbled, did some hand waving, glossed over the mind-bending implications of both possibilities and moved on to whatever snarky sci-cult reference was next because I’m a bad host. I acted like nothing happened and immediately got off the elevator.

WATCH: “Is the Universe Finite or Infinite?”

So I’m back to talk big Universe. And, if the Universe is finite, well, it’s finite. You could measure its size with a really long ruler. You could also follow up statements like that with all kinds of crass shenanigans. Sure, it might wrap back on itself in some kind of mind-bending shape, but if our Universe is infinite, all bets are off. In that case, it just goes on forever and ever and ever in all directions. And my brain has already begun to melt in anticipation of discussing the implications of an infinite Universe.

Haven’t astronomers tried to figure this out? Of course they have, you mortal meat man/woman! They’ve obsessed over it and ordered up some of the most powerful sensitive space satellites ever built to answer this question. Astronomers have looked deeply at cosmic microwave background radiation, the afterglow of the Big Bang. So, how would you test this idea by just watching the sky?

Researchers have searched for evidence that features on one side of the sky are connected to features on the other side of the sky, sort of like how the sides of a Risk map connect to each other, or the wraparound on a PacMan board. And, so far, there’s no evidence they’re connected.

This means that 13.8 billion light-years in all directions, the Universe doesn’t repeat. Light has been traveling towards us for 13.8 billion years this way, and 13.8 billion years that way, and 13.8 billion years that way; and that’s just when the light left those regions. The expansion of the Universe has carried them from 47.5 billion light years away. Based on this, our Universe is 93 billion light-years across. That’s an “at least” figure. It could be 100 billion light-years, or it could be a trillion light-years. We don’t know. Possibly, we can’t know. And it just might be infinite.

If the Universe is truly infinite, well then we get a very interesting outcome; something that I guarantee will break your brain for the entire day.

Consider this. In a cubic meter (or yard) of space. Alright, in a box of space about yay big (show with hands), there’s a finite number of particles that can possibly exist in that region, and those particles have a finite number of configurations considering their spin, charge, position, velocity, and so on.

Tony Padilla from Numberphile has estimated that number to be 10 to the power of 10 to the power of 70. That’s a number so big that you can’t actually write it out with all the pencils in the Universe. Assuming, of course, that other lifeforms haven’t discovered infinite pencil technology, or there’s a pocket dimension containing only pencils. Actually, it’s probably still not enough pencils.

WATCH: “Googol and Googolplex – Numberphile”

There are only 1080 particles in the observable Universe, which is much less than the possible configurations of matter in a cubic meter. If the Universe is truly infinite, if you travel outwards from Earth, eventually you would reach a place where there’s a duplicate cubic meter of space. The further you go, the more duplicates you’ll find.

Ooh, big deal, you think. One hydrogen pile looks the same as the next to me. Except, however, you’ll pass through places where the configuration of particles will begin to appear familiar, and if you proceed long enough, you’ll find larger and larger identical regions of space, and eventually, you’ll find an identical you. And finding a copy of yourself is just the start of the bananas crazy things you could do in an infinite Universe.

In fact, hopefully, you would absorb the powers of an immortal version of you, because if you keep going you would find an infinite number of yous. You would eventually find entire duplicate observable Universes with more yous also collecting other yous. And at least one of them is going to have a beard.

(Brought to you by Fraser Cain, from Universe Today)