Astrophysicist Paul Sutter explains
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00:00Do we live in a multiverse?
00:03No.
00:04I mean, yes.
00:07I mean, maybe.
00:09Look, it's kind of complicated and we're not exactly sure.
00:14I'm Paul Sutter and this is Paul Explains, the show where I, you know, explain.
00:21First, let's define what we mean by multiverse.
00:24We have the universe, which is by definition all the things.
00:30It's all the stars, all the planets, all the people and aliens.
00:34It's all the bits of fluff just floating around in the void.
00:37It is the entire thing.
00:40It's all the stuff.
00:43So in one sense, there's no such thing as the multiverse because the universe is already
00:47defined to be all the things.
00:50But maybe there are patches of the universe that have different physics or different realities.
01:00They have different forces or different particles and this is what we refer to as the multiverse.
01:09Now do we live in a multiverse?
01:12Maybe, maybe not.
01:15One of the most promising ways physically to get a multiverse is through something called
01:22inflation.
01:24Inflation is our model of one of the earliest and most momentous events in the history of
01:30the universe.
01:32In the inflation model, when our universe was barely getting started, when it was a billionth
01:38of a billionth of a billionth of a billionth of a second old, it became very large.
01:45It went from the size of, say, an atomic nucleus to around the size of a baseball.
01:51And this event has the possibility of never ending.
01:58Of inflation of the universe just always getting bigger and bigger and bigger all the time.
02:05And what we call the universe is just one small pocket of that much larger volume of the true
02:14universe.
02:15And in our little pocket, when inflation ended for us, we ended up with one set of physics
02:21and one set of forces and one set of particles and one set of reality.
02:26But past the confines of our little bubble, the greater universe is still going, still doing
02:34its thing, still inflating, and different pieces of it pinch off on their own with their
02:39own physics.
02:41Now, it's possible that inflation can lead to a multiverse.
02:48We don't know if inflation really happened.
02:50We suspect it did, but we're not entirely sure.
02:54And we're not sure if inflation demands the existence of a multiverse.
02:59It's possible that inflation just happened once and did it throughout the universe and
03:04that this is it.
03:07Or not.
03:08We've looked for evidence for a multiverse and have come up short.
03:13Like if another neighboring universe intersects with the bubble of our universe, we might
03:19be able to see signals of that.
03:22And we haven't seen anything.
03:24That doesn't rule it out yet, but there's no conclusive evidence for it.
03:30Even if there were a multiverse, we would never ever be able to access any of those other
03:35universes.
03:36We wouldn't be able to visit them.
03:38They wouldn't be able to visit us.
03:39For all intents and purposes, they wouldn't exist.
03:44So when it comes to multiverse, whether it exists or not, just focus on our universe because
03:51really, it's the only one we got.