What's outside the universe? | Sean Carroll and Lex Fridman

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GUEST BIO:
Sean Carroll is a theoretical physicist, author, and host of Mindscape podcast.

PODCAST INFO:

SOCIAL:

[LexClips]

Guest bio: Sean Carroll is a theoretical physicist, author, and host of Mindscape podcast.

[THCV]

If we encounter something outside of “the Universe”, then that logically becomes part of the expanded definition of the Universe itself, by definition. The Universe is the complete description of everything.

[ericroodhouse]

What is harder to comprehend. The finite or the infinite?

[keith]

It seems to me that we should agree on the definition of the universe as the totality of everything that exists. We should come up with other terms for things that are subsets of that… such as the observable universe or many worlds other than what we experience or other dimensions … And as long as I’m being presumptuous 😊 - we should admit that the universe is likely infinite and that is more than likely impossible to comprehend. But we should still try😊.

[JGKorny]

Consider the taught experiment: Imagine our universe as just one 3D slice of an immense 4D world (analogy of a sheet 2d slice of a 3d cube but at the next level). The universe didn't merely expand from a point, but dimensionally—it evolved from a point (0D), into a line (1D), spread into a plane (2D), and unfolded into the three-dimensional space we experience. But here’s the twist: it likely continued into a fourth dimension, beyond our observation. This explains why we can't see where the universe is expanding from—it's occurring in a dimension we don't perceive. What's more, the probability that we live in the original 3D slice formed at the start of this expansion is infinitesimally small. We are likely just one of countless 3D slices in a 4D cosmos, each experiencing its own version of reality! And the unfolding did not stop at 4D.
In our vast universe, imagine that what we experience as three-dimensional space is just one of many 3D 'slices' within a larger 4D cosmos. Particularly at the quantum level, these slices don't exist in isolation; they intersect. At every tiny point where these 3D worlds meet, quantum phenomena occur. This intersection explains the statistical nature of quantum mechanics, as each slice may experience different quantum events, contributing to the overall probabilities we observe. It's like multiple realities overlapping at points so small, they're governed by the laws of quantum physics. This model provides a unique perspective on how quantum mechanics might operate within a higher-dimensional space, suggesting that what we observe as randomness and superposition might actually be the result of simultaneous, intersecting realities at the quantum scale.

[readynowforever]

I finally figured out what’s “outside our universe”, after thinking about it for 28 years. And it gave me forever peace.

[Bonzeaux_Bleuxgrene]

Clearly what's outside the universe is packing peanuts

[MidnightMoon]

OMG! We only have this one Universe to exist in, and we can't leave?!! My claustrophobia is kicking in!

[kimberlykv]

I can't wait for a day off so that I can kick back and watch this episode. This is going to be good. Thank you, Lex!!!!

[Jeff-ttwj]

I like to imagine space is infinitely large and infinitely small. I think it’s entirely possible there’s infinitely smaller particles that we will never be capable of seeing, galaxies and universes beneath our fingertips that’s we are completely blind to. Surrounded by infinity at every scale.

[dabagz]

Entirely possible there are multiple universes. Think about an ocean and rain drops falling on the ocean. Each drop of rain is a universe, forever expanding in a ripple wave effect. You were randomly born into this rain drop for whatever reason. Nobody asked you for permission to be here. You just appeared and will disappear in the future . To quote Blade Runner : “ … like tears in the rain “

Time for a drink now lol

[wenapse]

Everything too big we have been calling it “infinite”. The ancient sailors from Greece, Scandinavia, and the Polynesia believed the sea was “never ending”. Some Native American tribes believed that the land was infinite. We humans have a bias to believe that big things that are beyond our perception must be infinite.

[Graybeard_]

We are here to experience. We shouldn't take others or ourselves too seriously. We should try our best and let go of the rest.

[kedarnadkarni]

Why should there be a starting point in time to the universe? That things should start at some point in time is only a human expectation. Also, why should the universe be finite in size? It is important either not to make tacit assumptions in asking such questions or to make clear that these assumptions are being made while asking these questions. If these assumptions do not hold good for the universe, the questions just melt away.

[manzoora]

My perspective is that there has to be an intelligence outside the universe to even coming up with idea of the universe. Let’s look at the simplest fundamental principles of the universe. Energy and matter can’t be created nor destroyed; they're both constant. Which begs the question: where do they come from? If there’s nothing outside the universe, then where was energy and matter created within the universe? It makes more sense logically that both of them have transformed into our universe. For example, my analogy is that imagine in slow motion a bullet penetrates through a door, transforming matter and momentum to the other side. So, if you observe within the universe and track where the bullet came from, you would always come to a conclusion that the bullet is untraceable because it disappears right at the door hole.

[nad]

If there's nothing outside our universe, then what it is expanding into and through?

[senju]

What if the universe never existed used to keep me up like in 3rd grade it genuinely scared me also to think that if we are the only life in the universe and our world somehow ended then space would just essentially just be dark and cold endlessly. I know planets and other celestial bodies exist but that was just my thought process at the time and it terrified me

[fatherdollarbill]

If the universe had a beginning, and they do say that. At least a theory or hypothesis.
Then can it have no outside? Can it be infinite?
All these questions are baffling and we won't understand without further information, which we may never get, but I hope we do, with further advanced tech.

[eb]

i always have 3 analogies for this: if you throw the dice, and its lets say a 4, and you ask why, most people would have no issue with saying its just a coincidence… so they can easily acknowledge that chance or randomness is an integral feature of our universe… but when you then make the leap to coincidence also being the causal origin of the universe, most people would not want to accept that answer, simply cause it wouldnt sound “profound” enough for them, hence sort of humanizing the question, which doesnt even make any sense at all, because if you look at the universe as a whole, its basically 100% void of any humans, so why exactly should our feelings tell us anything about the probability of a cause for existence? ridiculous

my 2nd analogy is, that maybe the question doesnt even make sense, just like it wouldnt make sense in mathematics to ask what is a any number divided by zero… and we can just never realize that, because we cant look at the universe from the outside, like we can at a mathematical equation

the 3rd one doesnt come from me personally, but instead from einstein, who said that asking what happened before the big bang would be like asking what is north of the north pole

so even if all of these analogies may not be completely satisfying, i am pretty sure thats about as close as we will ever get to an actual answer

[BillGoreArt]

Perhaps there is truly no outside of us as beings in relation to a fuller veiwpoint of existence. That we are entangled in this grand infinite tapestry.
Our preception being the limiting factor in easily understanding such a concept?
That we are not beings in a universe but we are the universe.