The Multiverse is real. Just not in the way you think it is. | Sean Carroll

What do physicists actually mean when they talk about the Multiverse? Sean Carroll explains.

The Multiverse is having a moment. From “Rick and Morty” to Marvel movies, the idea that our Universe is just one of many has inspired countless storylines in recent popular culture.

Why is the Multiverse so compelling? To theoretical physicist and philosopher Sean Carroll, one reason is that we’re drawn to wondering how things might have turned out differently. What if you had chosen a different career path? Married someone else? Moved to a different city?

Of course, there’s obviously no guarantee that you’re living out those alternate timelines in a different universe. But there are real scientific reasons to think that the Multiverse exists. And as Carroll explains, that possibility comes with some fascinating philosophical implications.

0:00 Hollywood’s Multiverse
1:35 Physics’ Multiverse: Cosmology vs. Many Worlds
3:28 The Many Worlds theory
4:25 Are there many versions of you?
6:39 Your alternate lives
8:09 Your one life in our Universe
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About Sean Carroll:
Dr. Sean Carroll is Homewood Professor of Natural Philosophy — in effect, a joint appointment between physics and philosophy — at Johns Hopkins University in Baltimore, and fractal faculty at the Santa Fe Institute. Most of his career has been spent doing research on cosmology, field theory, and gravitation, looking at topics such as dark matter and dark energy, modified gravity, topological defects, extra dimensions, and violations of fundamental symmetries. These days, his focus has shifted to more foundational questions, both in quantum mechanics (origin of probability, emergence of space and time) and statistical mechanics (entropy and the arrow of time, emergence and causation, dynamics of complexity), bringing a more philosophical dimension to his work.

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Read more of our stories on the multiverse:
Other than Doctor Strange, is the Multiverse good for anything?
Why the Multiverse is a “God-of-the-gaps” theory
The power of regret fuels our love of the Multiverse

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[larryfulkerson]

For a long time I thought Sean Carroll was a theoritical physist but it turns out that he's a real live person after all.

[alanbooth]

imagine a parallel world where Sean Carrol argues vehemently against the multiverse idea

[_J.F_]

So there may well be a parallel universe where you made all the right decisions, became a rock star, an astronaut, or a Hollywood celebrity, but it still wont change the fact that you are stuck in this universe where you are sitting watching a YouTube and wondering if multiverses are real or not.

[winstonsmith]

One time I got really stoned and decided to sit in front of a big mirror and the question occurred to me, “What if, right now in a parallel universe, my alter ego is also staring at a mirror, but it thinks I am the reflection? Does his hand move because I move, or do I move because he does? Am I just a reflection? How do I know that I’m the real one and not the reflection?!?” I then got a little freaked out, waved goodbye to my reflection, and ate a bowl of cereal. I’m okay now. 😂

[racookster]

I don't spend much time thinking about universes where one decision made my life different, but I do wonder about universes where different outcomes millions of years ago led to completely different worlds. Say, a world where a type of dinosaur became sapient. Or a mollusk. Or a miacid. Or even something as close as a different primate. The possibilities seem endless.

[Allofyoush]

Imagine a different universe for every picosecond of every directional spin of every electron in our universe. Effectively infinite.

[kami]

i make the bad decisions so me in another timeline can thrive

[peterszilvasi]

"If anything, it is the quantum measurements that force you to make a decision. Not your decision forcing different universes to come into existence." - Sean Carroll

[rezaulkarim]

The thing they did with the two opposite tables with identical plant pots but with slightly different orientations and plant types is really awesome in paying attention to detail.

[AgentSmithers]

I get that perspective and see how it can help. But I also found it helpful to think it's possible to "change" the past through actions done today. Not in the literal sense of actually altering events in the past, but in the sense that, if we change the way we think about the past or learn about it more, we can effectively change our understanding of it. So if you do a good deed or reveal truths formerly kept hidden, you can alter the way people understand the past and thereby also influencing the future. This is not at all supposed to be taken as concretely literal.

[Wajiiiiiiiiiiiiiiiii]

I can listen to Sean Carroll all damn day. He is one of the best communicators of science.

[jrvaughn]

I love the mirrored set in the episode about the multiverse. That was clever.

[nexstory]

My take on time travel, though it is always fun to postulate, is that if you were to go back to a former period in time, the entire universe would need to conspire to do the same.

[JonMajorCCIE]

I hate how hard this hit me. I've been struggling with some choices recently, and this video (unexpectedly) helped a lot.

[rushhit]

"...there are some decisions you can't undo."
That's also my wife's argument about her mother living in our house, of which I regretfully agreed to.
I could use a soul swap with any other *me* out there in the multiverse, any day now.

[larrynguyen]

Dr. Carroll is an amazing intellectual not just because of his intellect and expertise, but also because he able to explain these very complex concepts in such a concise and lucid way as to allow others who don't have the same background and education to understand.

[bigthink]

Are you a fan of Big Think? Check out bigthink.com for new articles every day!

[mikontisott]

gosh, I wish I grew up in a universe with teachers like this, absolutely captivating

[scottbrown]

Our obsession with the idea of a multiverse is a simple escape from responsibility. "Out there, another version of me is doing great things, so I can slack off and let the planet burn."

[tedlemoine]

I've watched Sean for years and never heard him refer to himself as a Philosopher