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Speaker 3: Hey Daniel, have you guys figured out what's inside a
Speaker 3: black hole?
Speaker 1: Yet unfortunately not still pretty confused.
Speaker 3: Okay, it sounds like you guys need to go back
Speaker 3: to the drawing board get some new ideas.
Speaker 1: I know, but like from where the smartest people on
Speaker 1: the planet have been stuck in this question for literally decades.
Speaker 3: See that is where you are going wrong. You are
Speaker 3: looking to the smart people. If you need wacky, crazy ideas,
Speaker 3: you need to ask the wacky crazy people like me.
Speaker 1: You're saying we should go to the insane asylum and
Speaker 1: ask people what they think is inside a black hole.
Speaker 3: I think that they could come up with some good ideas.
Speaker 3: They might be insane enough in the membrane to figure
Speaker 3: it out.
Speaker 1: Insane in the brain. Hi, I'm Daniel. I'm a particle
Speaker 1: physicist and a professor at UC Irvine. And if you
Speaker 1: didn't get my Cypress Hill reference, you're officially young.
Speaker 3: I am Katie. I am not a physicist. I like animals, though,
Speaker 3: and I like the universe. And I got that reference.
Speaker 1: Because you're insane in the membrane.
Speaker 3: Exactly, just the membrane, though the rest of me is
Speaker 3: perfectly sane.
Speaker 1: And Welcome to the podcast. Daniel and Jorge explain the
Speaker 1: universe in which we do our best to bring this
Speaker 1: insane universe into your brain. We try to make it
Speaker 1: all make sense, from the tiniest little quantum particles to
Speaker 1: the hugest swirling accretion disks surrounding super massive black holes.
Speaker 1: We have this hunch that maybe the universe is understandable,
Speaker 1: that it's a big mathematical puzzle, that we can eventually
Speaker 1: figure it out if we put all of our brains
Speaker 1: and membranes together, and our goal on this podcast is
Speaker 1: to explain all of it to you.
Speaker 3: Now, that's another song, super Massive black Hole. I think
Speaker 3: news soundtrack to that really sort of indie movie called Twilight.
Speaker 1: Are you sure that wasn't part of the hip hop
Speaker 1: wars in the nineties, super Massive black Hole.
Speaker 3: I couldn't say. In the nineties, I was not cool
Speaker 3: enough to know.
Speaker 1: Well, you know, maybe there are some secrets in music
Speaker 1: that can help us crack the mysteries of the universe,
Speaker 1: because you know, some people say the universe is musical
Speaker 1: and there's a connection between music and mathematics, right, So
Speaker 1: maybe we have been looking in the wrong places.
Speaker 3: Yeah, Like I've heard this in terms of string theory,
Speaker 3: where strings aren't you know, they're not like violin strings,
Speaker 3: but it's something about some like either vibration or pattern. Honestly,
Speaker 3: I do not understand it, but you know, I think
Speaker 3: that is interesting saying that there is the idea that
Speaker 3: a lot of the mysteries of the universe could be
Speaker 3: about certain frequencies or patterns, which is also what is
Speaker 3: the major components of music exactly.
Speaker 1: Although if you listen to Terrence Howard on Joe Rogan,
Speaker 1: it's all frequencies.
Speaker 3: Man, is all frequencies?
Speaker 1: Man?
Speaker 3: Why am I not on Joe Rogan? See, I just
Speaker 3: can say that too.
Speaker 1: I can because you believe that one times one equals one,
Speaker 1: and Terrence Howard proves that it equals to and wow,
Speaker 1: that's why you're just not mathematically qualified.
Speaker 5: To be.
Speaker 3: I just can't think outside of the box enough to
Speaker 3: not do mouth good exactly.
Speaker 1: But we are fascinated by the mysteries of the universe.
Speaker 1: We do think that there are mathematical solutions to them.
Speaker 1: Maybe they are encoded in the sonatas of Mozart. Maybe
Speaker 1: the engineers are right that it's all vibrations all the
Speaker 1: way down. But we hope that there is an explanation.
Speaker 1: And one of the biggest things that we need an
Speaker 1: explanation for is how to think about the universe on
Speaker 1: the smallest scales. What happens when things get really, really
Speaker 1: dense and really really tiny. One of the biggest puzzles
Speaker 1: in modern physics is how to put together the two
Speaker 1: pillars of our understanding of the universe, relativity and quantum mechanics.
Speaker 1: We've been banging our heads against this for almost one
Speaker 1: hundred years, basically since we've had relativity and quantum mechanics
Speaker 1: and realize that they are fundamentally incompatible at the smallest scale,
Speaker 1: and we've been trying to figure this out. And today
Speaker 1: on the podcast, we'll be exploring yet another attempt to
Speaker 1: unify relativity and quantum mechanics. So on the podcast today
Speaker 1: we'll be answering the question what is membrane theory?
Speaker 3: Okay, as a biology nerd, I'm pretty sure I can
Speaker 3: answer this. A membrane is a semi permeable barrier. So
Speaker 3: I did it. I solved it. Congratulations to me.
Speaker 1: What about the audio barrier between us and the listeners
Speaker 1: the ideas from our brains and that their brains have
Speaker 1: we permeated a membrane? I?
Speaker 3: Yes, why not? I don't know enough about audio engineering
Speaker 3: to say no or philosophy, So I'm gonna say yes.
Speaker 3: We're like salt ions through the airwaves, permeating the membrane,
Speaker 3: so hopefully you can reach homeostasis.
Speaker 1: So I'm not surprised that when you heard this phrase
Speaker 1: you thought of cellular membranes divisions between solutions. You want
Speaker 1: to keep osmosis from like moving all these bits of
Speaker 1: salt over here, or using fats to keep that over there.
Speaker 1: But it's not just in biology that we have membranes.
Speaker 1: It turns out that they are fundamental concept in theories
Speaker 1: of quantum gravity. But before we dig into that, I
Speaker 1: was curious what everybody else out there thought when they
Speaker 1: heard membrane theory, So, as usual, I asked our andre
Speaker 1: of volunteers to speculate on the question without the opportunity
Speaker 1: to use Google. So if you would like to join
Speaker 1: this group of volunteers in the future, please don't be shy.
Speaker 1: Write me to questions at Danielandjorge dot com. We all
Speaker 1: want to hear what you have to say. In the meantime,
Speaker 1: check out these answers from listeners. What do you think
Speaker 1: membrane theory is? Here's what people had to say that's
Speaker 1: the first time I'm hearing golf it.
Speaker 6: But if I had to guess membranes, the function of
Speaker 6: the memoranes are to pass on stuff in one direction
Speaker 6: and other stuff not in the other direction. So maybe
Speaker 6: we're talking about it's a mechanism about particle coexistence through
Speaker 6: a wall of things, something like that.
Speaker 7: Just I guess what comes to mind for me on
Speaker 7: that one is that it's something that you use to
Speaker 7: separate things, like in a fuel cell car. You know,
Speaker 7: you separate components and you make energy. Maybe it's like
Speaker 7: a desalination thing where you take salt.
Speaker 1: Out of water.
Speaker 7: So maybe there's some membrane here in the universe that's
Speaker 7: uh in that in space.
Speaker 5: I'm guessing membrane theory has to do with the outside
Speaker 5: of a cell. Maybe how the membrane, you know, protects
Speaker 5: the core of the cell and how it stays intact.
Speaker 1: I think it has to do with string theory. There
Speaker 1: are strings that vibrate in there one dimension, and I
Speaker 1: think a membrane is a.
Speaker 4: Something similar that can have more than one dimension.
Speaker 3: See, I'm I'm definitely with the theory that everything is
Speaker 3: a cell. If you look at the universe, it's just
Speaker 3: a giant body for some kind of huge animal. You know,
Speaker 3: it makes sense, right, you're saying the universe is alive. Yeah,
Speaker 3: it's a big maybe a giant cat. I don't know,
Speaker 3: have you ever looked at like a black cat? Right,
Speaker 3: it's it kind of has that sort of quantum mechanics
Speaker 3: and general relativity paradox. Right, it's like a fluid, it's
Speaker 3: a solid, it's sweet and le and then it bites you.
Speaker 3: So yeah, I think the universe could be a giant cat.
Speaker 3: And when you get down to the tiniest components there
Speaker 3: cells and yeah, it's been solved.
Speaker 1: You're welcome and we're done, Thank you very much. Physics
Speaker 1: is over. Katie wins all of the Nobel prices.
Speaker 3: Yay.
Speaker 1: Well, we're definitely hearing from listeners the connection to biology,
Speaker 1: which makes a lot of sense, and the idea of
Speaker 1: having two dimensional surfaces or even connections to string theory.
Speaker 1: So there's a lot of good stuff in here that
Speaker 1: we're going to dig into and explain in this episode.
Speaker 1: But a plus to all the listeners.
Speaker 3: I mean, I would assume that, yes, it's probably not
Speaker 3: like a cellular membrane, but if we're talking about a membrane.
Speaker 3: I would guess it is some kind of barrier through
Speaker 3: which certain physics transactions can occur. But that would be
Speaker 3: my guess.
Speaker 1: Is this whole podcast a physics transaction? We are taking
Speaker 1: your time and exchanging it for knowledge, is like a
Speaker 1: physics transaction, you know what?
Speaker 3: That's pretty good. I think I'm wondering about the exchange
Speaker 3: rate though, because that's that's the real issue.
Speaker 1: Yeah, I think we're too high on the jokes permitt
Speaker 1: it and too low and the physics permitted so far.
Speaker 1: Let's try to flip that right now.
Speaker 3: All right, well, okay, let me have it, Like, what's
Speaker 3: going on with this membrane theory?
Speaker 1: So membrane theory is an attempt to crack the puzzle
Speaker 1: of quantum gravity. So let's start with that. What is
Speaker 1: the puzzle of quantum gravity? Why do we want to
Speaker 1: crack it? What is the issue? Why are all the
Speaker 1: smart people on the planet thinking they need to go
Speaker 1: into the insane this islum if they can't figure this out.
Speaker 1: The basic issue is we have two ways to describe
Speaker 1: the universe. There's general relativity, which tells us about space
Speaker 1: and time and energy and the expansion of the universe.
Speaker 1: Describes a lot of the big stuff. It tells us
Speaker 1: how gravity works and how the universe is expanding and
Speaker 1: how far away galaxies are getting red shifted and all
Speaker 1: that good stuff. And then we have quantum mechanics, which
Speaker 1: describes the really small stuff, the little particles light and
Speaker 1: all the kind of quantum fields and sort of our
Speaker 1: understanding of microscopic matter. And the issue is that we
Speaker 1: don't know how to make these two things play well together.
Speaker 3: They don't play nice because I've actually, I think I've
Speaker 3: been on the show a couple times when we talked
Speaker 3: about this conundrum, and so it seems like, you know,
Speaker 3: when you have these mathematical theories that describe each of them,
Speaker 3: it works within it. So the general relativity math works
Speaker 3: within general relativity. It seems really nice and neat and good.
Speaker 3: Same thing for quantum mechanics. But then when you try
Speaker 3: to cross the beams the math beams, suddenly it doesn't work.
Speaker 3: Like if you're trying to use general relativity math to
Speaker 3: describe what you know is observed in experiments happening on
Speaker 3: sort of the quantum level or vice versa, it no
Speaker 3: longer works. Is that more or less?
Speaker 1: Yeah, I love crossing the math beams. That's awesome. I
Speaker 1: want a T shirt that says I'm crossing the math beams.
Speaker 1: But yeah, that's basically the idea. And remember that what
Speaker 1: we're doing in physics is trying to build a mental
Speaker 1: model that describes the universe easy. Those mental models are
Speaker 1: always imperfect, they're always incomplete, they're always simplifications. Even if
Speaker 1: you're talking about like the flight of a baseball, Right,
Speaker 1: how does a baseball fly across the field? Well, I'm
Speaker 1: going to use a parabola in Newton's equations, but I
Speaker 1: can't do the calculation very easily. I fad to include
Speaker 1: air resistance, so I decide I'm not including that because
Speaker 1: it's probably not important, and really, to answer my question
Speaker 1: of whether the guy's going to catch it, air resistance
Speaker 1: doesn't matter. I'm not going to include effects of humidity
Speaker 1: and the sizillion things I could include in my model
Speaker 1: to make it a very accurate description of the universe
Speaker 1: that I don't need to to answer my question. And
Speaker 1: so the models that we build to answer questions about
Speaker 1: the universe are always incomplete. There are always approximations, but
Speaker 1: they're still very, very useful, And that's The issue with
Speaker 1: quantum mechanics and general relativity is that they are two
Speaker 1: different approximate descriptions of the universe that make different approximations,
Speaker 1: different foundational assumptions that go in building those models that
Speaker 1: are incompatible, and they let us describe different parts of
Speaker 1: the universe, as you say, very very well. So if
Speaker 1: I want to talk about how two electrons scatter off
Speaker 1: of each other, I can use quantum mechanics and talk
Speaker 1: about how they interact and the virtual particles they exchange
Speaker 1: or the fields that ripple between them, and it all
Speaker 1: works out amazingly well. And that can ignore what general
Speaker 1: relativity would do in that situation because it's irrelevant. It's
Speaker 1: like the wind resistance or the humidity on the baseball.
Speaker 1: It doesn't affect the calculations, so I can ignore it.
Speaker 1: Or if I want to say, hey, how do galaxies
Speaker 1: form and how do they swirl around each other? I
Speaker 1: can use general relativity to answer those questions, and I
Speaker 1: can ignore the quantum effects because who cares what one
Speaker 1: electron does in Andromeda doesn't affect whether our galaxy is
Speaker 1: going to crash into that galaxy. General relativity dominates. The
Speaker 1: amazing thing is that in every situation in our universe,
Speaker 1: you can use either quantum mechanics to explain it or
Speaker 1: general relativity and ignore the other one. They're like a
Speaker 1: perfect divorced couple that have separate to their lives and
Speaker 1: never have to interact. You know, there are no arguments
Speaker 1: at McDonald's about who's taking the case. They're co parenting
Speaker 1: the universe. And so you might think, all right, great,
Speaker 1: what's the problem, right co parents can live in harmony
Speaker 1: without ever talking to each other. Well, there's two problems.
Speaker 1: One is that's really unsatisfying, right, Like, we want one
Speaker 1: explanation for the universe. We don't want two different explanations.
Speaker 1: We don't want a Russiaman universe where both parents tell
Speaker 1: very very different stories about what's going on. Right.
Speaker 3: Note, we think that.
Speaker 1: There is one story about the universe. There's something that's happening,
Speaker 1: and that there are rules that are being followed, and
Speaker 1: we want to know what they are. We want our
Speaker 1: best approximation of them. So it's deeply unsatisfying to have
Speaker 1: two different, incompatible theories of the universe. And also, there
Speaker 1: are moments in the universe, a very few places in
Speaker 1: times when you can't ignore one war or the other.
Speaker 1: You need both things like the heart of a black
Speaker 1: hole a singularity. In general, relativity is incompatible with quantum mechanics,
Speaker 1: which says you've got to have some fuzziness or the
Speaker 1: Big Bang or the very early universe when things were really,
Speaker 1: really hot and dense. You need the rules of quantum
Speaker 1: mechanics to describe those particles. But you can't ignore gravity
Speaker 1: because things are so hot and so dense. So we
Speaker 1: desperately want to find a way to bring these two together.
Speaker 1: But as you say, the math beams don't cross, right.
Speaker 3: I mean, it's like, as physicists you now kind of
Speaker 3: have to play as a couple's therapists, where you have
Speaker 3: these two theories that are essentially speaking different languages, and
Speaker 3: they cannot come to an agreement, and they can be
Speaker 3: perfectly functional on their own, but then when they come together,
Speaker 3: they are unable to communicate. And the Yeah, I mean,
Speaker 3: it seems like resolving that difference between the two theories,
Speaker 3: like resolving why they don't work with each other, would
Speaker 3: actually reveal some big things that we just fundamentally have
Speaker 3: not understood yet about the universe.
Speaker 1: M M. You know, I've heard anecdotally about couples that
Speaker 1: don't actually speak the same language you know where they
Speaker 1: have like literally have now yet they've fallen in love.
Speaker 1: That's actually true, they have some other love language.
Speaker 3: Hi language interpret of there love.
Speaker 1: At first sight, right, doesn't love it first word.
Speaker 3: Yeah.
Speaker 1: Anyway, you're right that quantum mechanics in general relativity don't
Speaker 1: get along, and one of the reasons is that they
Speaker 1: are built on very different assumptions. Like general relativity says
Speaker 1: the universe is smooth, it's continuous, it's precise, there's an
Speaker 1: infinite number of locations. It says that you can divide
Speaker 1: space an infinite number of times, like relativity agrees with
Speaker 1: Zeno's paradox, right that between you and the candy store,
Speaker 1: there's always a distance that you can cut in half.
Speaker 1: Space from the point of view of general relativity is
Speaker 1: something that's smooth and continuous and you always have a
Speaker 1: very specific location, whereas quantum mechanics says not nothing is
Speaker 1: actually smooth and continuous. There aren't not infinite number of
Speaker 1: locations between any two points. Things are discrete and chunky.
Speaker 1: A beam of light is actually made up of little
Speaker 1: pieces of light, little packets of light. Everything in the
Speaker 1: universe is discrete, and it's also imprecise. None of these
Speaker 1: little packets have a precise location that have probabilities. So
Speaker 1: you see the foundations of these two theories are very
Speaker 1: very different. They start from two very different places, and
Speaker 1: so weave in them together has a lot of challenges.
Speaker 1: People have been trying to make theories of quantum gravity
Speaker 1: to say, hey, let's take gravity and try to describe
Speaker 1: it in the language of quantum mechanics. For example, think
Speaker 1: of it like a quantum field. They are exchanging virtual particles.
Speaker 1: They even have a name for these particles. It would
Speaker 1: be the graviton. But when you sit down and try
Speaker 1: to do those calculations, gravity is different from the other
Speaker 1: quantum forces because it couples to itself. Everything that has
Speaker 1: energy has gravity, and so if you emit a graviton,
Speaker 1: it also feels gravity, and it emits gravitons, which emit
Speaker 1: more gravitons. You can infinite number of graviton and then
Speaker 1: you start to get nonsense answers. So as you say,
Speaker 1: the math beams don't cross.
Speaker 3: So in terms of gravitons, is that something that has
Speaker 3: ever been able to be studying in the same way
Speaker 3: that you can study protons or is it just sort
Speaker 3: of a byproduct of this? Seems like this could be
Speaker 3: a thing based on the math that we have theorized about.
Speaker 1: Yeah, gravitons are purely theoretical, and they're not even coherently theoretical.
Speaker 1: Theories that have gravitons in them just don't work their
Speaker 1: problems with them, and so it's not just that we
Speaker 1: haven't seen them. We don't even understand how they would
Speaker 1: work if they did exist. And there also would be
Speaker 1: really really hard to spot, Like if you're thinking about
Speaker 1: gravitational waves from rotating black holes, for example, those are
Speaker 1: not gravitons. Those are ripples in space and time. They
Speaker 1: are like a beam of light. Gravitons would be like
Speaker 1: taking that beam of light and breaking it up into photons.
Speaker 1: So you take that gravitational wave and now break it
Speaker 1: up into tiny little gravitons. But even gravitational waves are
Speaker 1: really hard to see. Gravitons would be much much tinier,
Speaker 1: well beyond our capability. But also mathematically they just don't work.
Speaker 1: If you try to do calculations with gravitons, you get
Speaker 1: weird answers, like what's the probability that this electron is
Speaker 1: going to go left. Oh, one hundred and forty percent.
Speaker 1: What that doesn't make any sense, right, And so that's
Speaker 1: telling you that fundamentally there is a problem with the
Speaker 1: mathematics that you need to go deeper and start from
Speaker 1: something else, change one of your assumptions in order to
Speaker 1: make a working theory of quantum gravity.
Speaker 3: I mean this kind of reminds me in biology of
Speaker 3: how like the history of biology and medicine, where we
Speaker 3: would start to understand things like we would start to
Speaker 3: understand how certain medications work, or you know, understand things like,
Speaker 3: you know, a man and a woman make a baby
Speaker 3: and the like. There seems to be these germinal cells responsible.
Speaker 3: But then we didn't have the ability to get tiny
Speaker 3: enough inside the human body where we couldn't see like proteins,
Speaker 3: we couldn't see you know, maybe we at some point
Speaker 3: could see cells, but we couldn't see DNA. So there
Speaker 3: were so many strange and interesting theories that kept circling
Speaker 3: around trying to get closer and closer to the truth.
Speaker 3: Like there were really funny ones like imagining that there's
Speaker 3: just like a tiny person inside of a sperm cell
Speaker 3: and then that grew into a baby. But essentially it's
Speaker 3: like we were able to make scientific observations, but without
Speaker 3: the ability to get small enough in terms of like
Speaker 3: we didn't have electron microscopes, we didn't have the technology
Speaker 3: or understanding to study DNA. These theories could not kind
Speaker 3: of you know, interweave until we got to that point.
Speaker 3: And that kind of seems like where, you know, sort
Speaker 3: of like what's happening with the universe? Like we're able
Speaker 3: to you know, make all of these really interesting scientific
Speaker 3: observations and they're not necessarily wrong, but there is some
Speaker 3: fundamental aspect that it's not necessarily that it's too small
Speaker 3: to see, but something that we can't see yet or
Speaker 3: something that is really hard to observe that might help
Speaker 3: tie these things together exactly.
Speaker 1: And because it's a question mark, it's deeply unsatisfying to
Speaker 1: not have figured it out. We suspect that when we
Speaker 1: do figure it out, it'll be something new, something fascinating,
Speaker 1: something that tells us about the basic nature of the universe,
Speaker 1: because it's telling us that Gr's description of the universe
Speaker 1: is wrong. Space is not just some bendable manifold, and
Speaker 1: the quantum mechanics description of the universe is wrong in
Speaker 1: some important way. That's what I love about physics, because
Speaker 1: it's not just I have a model in my head
Speaker 1: that is predicting the universe. You can then look at
Speaker 1: that model and ask questions about it that are philosophical
Speaker 1: and like, huh, why does the universe work this way?
Speaker 1: Or you can look at it and say, oh, that's
Speaker 1: why time flows forwards and there's only one dimension of
Speaker 1: it in three dimensions of space. If you have that
Speaker 1: fundamental theory of the universe, we hope that those kind
Speaker 1: of answers can come from it deep insights about the
Speaker 1: very nature of reality. People who think like, oh, that's
Speaker 1: so weird and abstract, I mean, that's like the context
Speaker 1: of our whole lives, you know, our entire existence. Understanding
Speaker 1: the basic nature of reality of space and time and
Speaker 1: matter and energy like that is the stage of our life,
Speaker 1: the context of our existence. The stakes could literally not
Speaker 1: be higher.
Speaker 3: I mean it's interesting because I'm really curious about things
Speaker 3: like animal and human behavior, understanding them and understanding things
Speaker 3: like perception and you know. But those kinds of questions
Speaker 3: I don't see as too fundamentally different from the questions
Speaker 3: that physicists are answering because in a way, you know,
Speaker 3: our perception of things are sort of like behaviors and stuff.
Speaker 3: That is how we're able to perceive the universe. And
Speaker 3: so these kinds of questions of understanding. Of course, the
Speaker 3: methodologies are very different and what we find are going
Speaker 3: to be very different with these two questions, but it's
Speaker 3: that's still that kind of desire to understand what are
Speaker 3: we and where are we? How do we function and
Speaker 3: how do we function in real to our environment? And
Speaker 3: you know, of course the universe being the largest environment
Speaker 3: that we can think of in which we are. But
Speaker 3: you know what, we should probably take a quick break
Speaker 3: while I really ponder an egg and the membrane of
Speaker 3: an egg and try to think about whether this is
Speaker 3: something that could describe the universe.
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Speaker 3: All right, so we are back. I've been staring at
Speaker 3: this egg for five minutes, Daniel can attest to that,
Speaker 3: and you know, I think maybe the universe could be
Speaker 3: an egg with yellow stuff on the inside. What do
Speaker 3: you think?
Speaker 1: I love your egg theory of the universe. I want
Speaker 1: to see the math behind it before I really commit
Speaker 1: to it.
Speaker 3: One plus one equals two? Or wait, one time is
Speaker 3: one equals too? I accidentally did I'm so bad at math.
Speaker 3: I was trying to make a joke where I did
Speaker 3: it bad and I did it correctly.
Speaker 1: Oops oops oops.
Speaker 3: So, Daniel, I really want to get deeper into these
Speaker 3: ideas because we've talked about how these things don't seem
Speaker 3: to add up, and these attempts to make things add
Speaker 3: up have in some sense, I don't want to say failed,
Speaker 3: but they haven't reached the finish line yet. So, like
Speaker 3: rabtons don't make sense yet, are there is there anything
Speaker 3: promising where we are seeing some revelations that may help
Speaker 3: us get closer to why there is this fundamental miscommunication
Speaker 3: between general relativity and quantum mechanics.
Speaker 1: So there definitely has been some progress. Nobody's totally figured
Speaker 1: it out, but some of the smartest folks on the
Speaker 1: planet have some ideas. And before we get into membrane theory,
Speaker 1: you need to take a step back and understand where
Speaker 1: it came from, which is from string theory.
Speaker 3: Okay, I'm excited because I remember I remember watching I
Speaker 3: think like a PBS nova thing and they tried to
Speaker 3: explain string theory and it just confused me more than
Speaker 3: I think, you know, like if you just said, like,
Speaker 3: imagine what string theory is, I'd probably be less confused
Speaker 3: at that point, until after watching this documentary. I'm not
Speaker 3: I don't want to be mean to PBS, but I
Speaker 3: don't think they really explained it very well because it
Speaker 3: was like they were like these vibrating strings like on
Speaker 3: a violin, and it's like, I don't know that that
Speaker 3: makes a lot of sense, and I'm confused. You mean,
Speaker 3: there's tiny violins everywhere. What's going on? Are the world's
Speaker 3: smallest violins making up the universe? So I do want
Speaker 3: to understand better.
Speaker 1: All right, Let's see if we can do better than
Speaker 1: Brian Green on PBS. The idea is to avoid some
Speaker 1: of the mathematical problems that come when you try to
Speaker 1: cross the beam those infinities. A lot of those infinities
Speaker 1: come from the basic assumption that things are points, that
Speaker 1: particles are tiny dots, because those have infinities in them.
Speaker 1: There's infinite densities and the zero volume, et cetera. So
Speaker 1: instead of having points, string theory says, what if everything
Speaker 1: is a line? So a point is like zero dimensions, right,
Speaker 1: this doesn't go in any way, but a string is
Speaker 1: one dimension. It's like, well, let's have it have some extent,
Speaker 1: and having it have a length means it's not infinitely densitymore,
Speaker 1: there's like a fundamental length to it, and that avoids
Speaker 1: some of the infinities in the calculations. Is like a
Speaker 1: minimum size to stuff, and that's the length of a string.
Speaker 1: And so these strings would be the fundamental bits of
Speaker 1: the universe. Essentially the universe is strings. But these strings
Speaker 1: can do things. They can wiggle, right, just like strings
Speaker 1: in our world, like a violin.
Speaker 3: String can wiggle Daniel, or.
Speaker 1: Or a guitar string if you prefer that. But we
Speaker 1: can't see those wiggles directly, and so what we see
Speaker 1: is something really zoomed out, Like the string wiggles this way,
Speaker 1: it looks like an electron. When you zoom way out,
Speaker 1: the string wiggles that way, it looks like a mue.
Speaker 1: On the string wiggles another way, it looks like a quark.
Speaker 1: So the idea is not that the electrons and the
Speaker 1: quarks are made of tinier particles the way that like
Speaker 1: the atom is made of smaller particles, but that you
Speaker 1: get something fundamentally different. Right, we need something fundamentally different
Speaker 1: to solve this puzzle of quantum gravity. We need a
Speaker 1: new idea, And so we say that these particles are
Speaker 1: instead made of vibrating strings, and they just look like
Speaker 1: different particles because we're too zoomed out to see the details.
Speaker 3: I guess for me, the question is like I understand
Speaker 3: the difference between a point and a line in terms
Speaker 3: of dimensionality, but in terms of like a line of
Speaker 3: what Like That's where I get caught up, because I,
Speaker 3: you know, usually it's so hard to think about the
Speaker 3: fundamental like unit of something because maybe this is just
Speaker 3: biology brain, but everything has a smaller thing in it, right,
Speaker 3: Like you've got You've got a mouse, and the mouse
Speaker 3: has tissues, and the tissues have cells, and the cells
Speaker 3: have proteins, and the proteins have molecules, and the molecules
Speaker 3: have atoms, and the atoms have quarks, et cetera, et cetera.
Speaker 3: I might have skipped a few steps, but you get
Speaker 3: the idea, which is that I'm always thinking, like, what
Speaker 3: what do you mean, like a string of what? A
Speaker 3: line of what?
Speaker 5: So?
Speaker 3: How has that resolved? Like what is because I'm assuming
Speaker 3: it is not like a literal strand of you know,
Speaker 3: like in in biology, like a strand of protein. Like
Speaker 3: if you're like, there's a string of something, I'm thinking like, oh,
Speaker 3: is it proteins? Like you know, is it lipids? What's
Speaker 3: it made out of? So in in physics, like what
Speaker 3: is this line?
Speaker 1: Yeah, it's a great question. And I understand what you're saying.
Speaker 1: You're imagining string your mind. And you know, if you're
Speaker 1: thinking about like a line of frosting on a cake,
Speaker 1: you're thinking that squeezed out of some tube, and the
Speaker 1: line of frosting is made out of that frosting, and
Speaker 1: therefore the frosting is the basic universe stuff, not the
Speaker 1: line of it, and so you're wondering, like, well, what
Speaker 1: that string made out of? What is string stuff? The
Speaker 1: answer is, we don't know. And you're right that the
Speaker 1: pattern is that stuff is made of smaller stuff, which
Speaker 1: has made of smaller stuff, which is made of smaller stuff.
Speaker 1: And so far we've never seen anything that is just
Speaker 1: itself that is not made of something small.
Speaker 3: That's the truth.
Speaker 1: You're absolutely right. But we have this hunch. We have
Speaker 1: this hunch that maybe it is that maybe there's a
Speaker 1: bottom to the explanations of the universe. We don't know,
Speaker 1: and there are philosophers out there who argue that it
Speaker 1: could be infinitely regressive, right, that you just could keep
Speaker 1: going forever and ever and ever, and there is no
Speaker 1: foundational firmament to the universe. Everything is made of something smaller.
Speaker 3: I hate it either way, Daniel, Like either explanation I did.
Speaker 3: It feels uncomfortable somehow, right, Like if the explanation is
Speaker 3: like there is a smallest unit and it's a line
Speaker 3: that wiggles, I'm like really, And then if you're like no,
Speaker 3: but then the line that wiggles can you can infinitely
Speaker 3: get smaller and smaller and smaller, and then still that
Speaker 3: it's like, really, it's so hard, And I feel like
Speaker 3: maybe the reason it's so difficult is that our human
Speaker 3: brains are geared towards a certain type of understanding of
Speaker 3: things based on what our evolutionary needs are in terms
Speaker 3: of something has a start point and endpoint, or something
Speaker 3: is made out of something else and time goes from
Speaker 3: point A to point B. When someone who is not
Speaker 3: a physicist is trying to think about these things, I
Speaker 3: think about stuff that is probably not very relevant to it.
Speaker 3: Like when I think of I don't know, you keep
Speaker 3: talking about wiggly lines, and I just think about al
Speaker 3: dente spaghetti and that's not what it is and it
Speaker 3: can't be. But it's so hard to think of. Okay,
Speaker 3: say there's a basic unit that can't get any smaller,
Speaker 3: but it's not made out of anything, and that, you know,
Speaker 3: it just kind of breaks my brain. I cannot conceive
Speaker 3: of that.
Speaker 1: Well, let me put it in another way, which is
Speaker 1: maybe easier to sit with in your brain, which is,
Speaker 1: we don't know whether strings, if they exist, are the
Speaker 1: fundamental basis of the universe, or if they're made of
Speaker 1: something smaller. You can put it that way, right, and
Speaker 1: we can put it that way because we actually don't
Speaker 1: have to know. And this is one of the beautiful
Speaker 1: things about physics is that we can do calculations at
Speaker 1: various scales ignoring the internal details, not having to know them.
Speaker 1: Like when we did that calculation of the baseball flying
Speaker 1: across the field, we didn't have to keep track of
Speaker 1: all the electrons and even the air resistance and all
Speaker 1: those details to mostly get the right answer. You can
Speaker 1: do physics at lots of different scales. So even if
Speaker 1: the universe infinitely is made of smaller stuff, or if
Speaker 1: there is some fundamental chunk to it, we can still
Speaker 1: do physics about it without even knowing the answer. So
Speaker 1: thanks to the universe for being understandable at lots of levels.
Speaker 1: Even before we figured out quantum gravity. You can imagine
Speaker 1: another scenario where in order to do any calculation you
Speaker 1: had to understand all the little bits inside of it.
Speaker 1: You have to figure out the fundamentals of quantum gravity
Speaker 1: before you could make chicken soup, right, But fortunately in
Speaker 1: our universe you can throw baseballs and make chicken soup
Speaker 1: and play violins without understanding all the details, so we
Speaker 1: can make progress. We can say, well, maybe electrons are
Speaker 1: made of strings without knowing whether those strings are also
Speaker 1: made of something else, and still have some insight into
Speaker 1: this layer of the universe, without knowing if there are
Speaker 1: more layers beyond it.
Speaker 3: So we've got possible strings that we don't know exactly
Speaker 3: if they exist. But it's a line that can wiggle
Speaker 3: in the way in which it wiggles forms some kind
Speaker 3: of different thing which I can kind of accept at
Speaker 3: this point. Is that sort of it? In terms of
Speaker 3: string theories, it seems like there would probably be a
Speaker 3: lot more complexity involved.
Speaker 1: Yeah, there is more complexity. The mathemat of those strings
Speaker 1: is very cool. At first, when people were working it out,
Speaker 1: they were only able to use strings to describe some
Speaker 1: kinds of particles, particles that we call bosons, which are
Speaker 1: photons and the W and the Z and the higgs
Speaker 1: and the gluons. These are all the bosons, the force
Speaker 1: carrying particles. So the original string theory could only describe bosons.
Speaker 1: And then people worked on it and found new ways
Speaker 1: for those strings to wiggle, so they could also describe fermions,
Speaker 1: and that's called super string theory. Super as a reference
Speaker 1: to this other idea, supersymmetry, which connects fermions and bosons.
Speaker 1: Check out our whole episode about that. But so then
Speaker 1: people developed super string theory, and then there was this
Speaker 1: sort of revolution in the nineteen eighties when people got
Speaker 1: really excited about it. They call it the first super
Speaker 1: string revolution, and that's when people realized, wow, this string
Speaker 1: theory is not just a cool mathematical model. It can
Speaker 1: describe all the kinds of particles in our universe. And
Speaker 1: also it seems like a very promising theory of quantum gravity.
Speaker 1: They were able to avoid some of the infinities of
Speaker 1: earlier attempts the problems with gravity by describing things in
Speaker 1: terms of strings. So it was a very exciting time.
Speaker 1: A lot of people worked on it, and the problem
Speaker 1: was that they had lots of different ideas. So there's
Speaker 1: not like one string theory or one way to do
Speaker 1: string theory. People figured out a bunch of different kinds
Speaker 1: of string theories, like you can have strings that are
Speaker 1: always open like they're just lines, or strings that are
Speaker 1: closed which means they're loops. Or you can have a
Speaker 1: theory with strings sometimes are open and sometimes are closed,
Speaker 1: or different kinds of ways to solve super gravity. And
Speaker 1: so at the end of the eighties, there was sort
Speaker 1: of a confusion because there were like five different types
Speaker 1: of string theory that were all seemed very very different
Speaker 1: and all kind of worked, and people weren't sure sort
Speaker 1: of where to go from.
Speaker 3: There, right, I mean, that seems kind of tricky because
Speaker 3: it's almost like you're sort of filling in the gaps,
Speaker 3: right with these different theories, and you can it seems
Speaker 3: like they were able to come up with different sort
Speaker 3: of math or different theories that did fill that gap
Speaker 3: in different ways, and so I don't know how you
Speaker 3: would pick which one works if they all sort of
Speaker 3: can on average kind of like fix that gap.
Speaker 1: And that's very unsatisfying, right, because we think the universe
Speaker 1: is following a set of laws. We think there is
Speaker 1: one set of laws, and so then if you find
Speaker 1: like two explanations for the universe that both work, you're like, well,
Speaker 1: which one is really happening?
Speaker 4: Right?
Speaker 5: You know?
Speaker 1: Is a deep philosophical question.
Speaker 3: Could there actually be something we're on this level? There
Speaker 3: could be multiple sets of rules that all work at
Speaker 3: the same time.
Speaker 1: Yeah, philosophers think it's possible that there are multiple explanations
Speaker 1: for the universe, multiple theories that predict the universe and
Speaker 1: describe it and explain what's happening, but have fundamentally different
Speaker 1: stories about sort of what's going on behind the curtain.
Speaker 1: We don't know if that's possible, but there's a group
Speaker 1: of philosophers who think it might be. And boy, I
Speaker 1: hope they're wrong, because that would be very frustrating. In
Speaker 1: the stuber strink community also was hoping they were wrong.
Speaker 1: And we're trying to figure out this puzzle. And one
Speaker 1: way to try to f figure it out is to
Speaker 1: see are there connections between these different theories? Can we
Speaker 1: show that actually these theories are really the same thing
Speaker 1: dressed up in different clothing, Like are we really just
Speaker 1: telling the same story using different words or using different symbols.
Speaker 1: It harkens back to like the nineteen twenties when people
Speaker 1: were developing quantum mechanics, for example, and you had Schrodinger
Speaker 1: he had his wave equation of quantum mechanics, and you
Speaker 1: had Heisenberg he had his matrix formulation of quantum mechanics.
Speaker 1: And those two guys did not like each other. In fact,
Speaker 1: they hated each other, and they also disliked each other's ideas,
Speaker 1: Like Heisenberg really didn't like Schrodinger's wave equation. He thought
Speaker 1: it made quantum mechanics like too visual and gave you
Speaker 1: a mental image. When instage, you'd just focus on the
Speaker 1: math of the matrices, and everybody else hated Heisenberg's matrices
Speaker 1: because nobody could understand what they meant. And then a
Speaker 1: few decades later John von Neumann showed actually they're the same.
Speaker 1: They make the same calculations. You can convert one into
Speaker 1: the other, and so they're just like two different ways
Speaker 1: to write the same thing, the way that like algebra
Speaker 1: and geometry are fundamentally the same. You want to solve
Speaker 1: a system of equations like two lines, you can either
Speaker 1: draw them on a piece of paper and see when
Speaker 1: they cross, or you can do a bunch of algebra
Speaker 1: and solve for it. In the end, those feel like
Speaker 1: two different kinds of math, but they really are revealing
Speaker 1: the same thing, or the same relationship between concepts. So
Speaker 1: people were wondering, can we do that for string theory?
Speaker 1: Can we show that these different string theories they're called
Speaker 1: type one, type two A, type two B, so thirty.
Speaker 3: Two it sounds like a disease.
Speaker 1: And E eight x E eight. These are crazy names,
Speaker 1: I know, terrible, terrible names, be deeply offended.
Speaker 3: I have type one string theory.
Speaker 1: I'm so sorry, can you? So there's a group for that.
Speaker 1: So people were wondering, is it possible these actually are
Speaker 1: different mathematical expressions for the same phenomena, And it was
Speaker 1: a hard problem. But there are smart people out there.
Speaker 1: Edwitten maybe one of the smartest dudes ever. He's at
Speaker 1: the Institute for Advanced Studies near Princeton, and he was
Speaker 1: playing with these strings. Remember, the strings don't just exist
Speaker 1: in our three dimensions of space. The math works best
Speaker 1: if space has nine dimensions. So these strings are one
Speaker 1: dimensional lines through nine dimensional space our three dimensions, and
Speaker 1: then six more dimensions that we can't sense or perceive
Speaker 1: or really experience in any way. But the strings need
Speaker 1: them in order to make their math wiggle correctly.
Speaker 3: Hmm, yeah, no, I mean I think this is it's
Speaker 3: always a wild time trying to think about other dimensions,
Speaker 3: because we could probably explain other dimensions with math, but
Speaker 3: to try to conceptualize them, I don't know if that's
Speaker 3: even possible with our brains, given that our brains are
Speaker 3: three dimensional brains and function in a sort of three
Speaker 3: dimensional way. So without your neurons being able to span
Speaker 3: into the other six dimension. That seems difficult.
Speaker 1: It is very difficult. You're right. We intuitively think in
Speaker 1: three dimensions. It's very hard to think in additional dimensions.
Speaker 1: It's even hard to think in fewer dimensions. Like if
Speaker 1: you try to imagine a two D sheet or one
Speaker 1: D line, you're imagining it in three D space. You
Speaker 1: put that sheet into three D space, or that line
Speaker 1: in three D space. Or if I tell you imagine
Speaker 1: a zero dimensional dot, you think of a point and
Speaker 1: you skitch it out into some three D space because
Speaker 1: that's the natural playground of our mind. So if you
Speaker 1: can't go down the dimension, there's no hope in going
Speaker 1: up a dimension. It's really very difficult.
Speaker 3: I almost passed out once trying to think about like nothing,
Speaker 3: like going you know, sort of the zero dimension thing,
Speaker 3: trying to think about nothing. And I felt very weird
Speaker 3: to try to think about that for too long. It
Speaker 3: felt like my brain was kind of leaving my body.
Speaker 3: Maybe I was just sleepy, I don't know, but yeah.
Speaker 3: There's also that book Flat Landers, where it tries to,
Speaker 3: in an artistic way, represent how difficult it is to
Speaker 3: bridge the gap between two D existence and a three
Speaker 3: D existence. But yeah, fundamentally, even that book is describing
Speaker 3: it as a visual experience, where having vision requires three dimensions.
Speaker 3: It seems so.
Speaker 1: Yeah, And so making progress on this requires super smart
Speaker 1: dudes to do superstring theory. And so ed Witten was
Speaker 1: thinking about these nine dimensional strings, and so those theories
Speaker 1: are ten dimensional because it's nine spatial dimensions and one
Speaker 1: time dimension. He was thinking about these nine dimensional strings,
Speaker 1: and he was inspired by this leap from zero dimensional
Speaker 1: points to one dimensional lines strings, and he was wondering,
Speaker 1: should we take it a step further? Instead of thinking
Speaker 1: about these things as one D strings in nine dimensional spaces,
Speaker 1: maybe they're actually two dimensional objects membranes, right, sheets in
Speaker 1: higher dimensional space. And so these would be like two
Speaker 1: D sheets in ten dimensional space, which look like one
Speaker 1: dimension objects strings if you only look at them in
Speaker 1: nine dimensions. So the idea is he invents this extra dimension,
Speaker 1: this eleventh dimension or a tenth dimension of space and
Speaker 1: extends the strings into that space to make them into membranes.
Speaker 3: So more like a sheets theory.
Speaker 1: Yeah, exactly, from strings to.
Speaker 3: Sheets sponsored by sheets the convenience store and gas station.
Speaker 1: So the exciting thing is that Witten thought that if
Speaker 1: you worked with membranes instead of strings, you could explain
Speaker 1: all these different string theories. That these five string theories
Speaker 1: were actually just five different ways to look at the
Speaker 1: same sheet. So you roll it up this way, it
Speaker 1: looks like one. You roll it up another way, it
Speaker 1: looks like another. You look at it from this perspective,
Speaker 1: it looks like a different string theory. But these five
Speaker 1: string theories that people were playing with and confused about
Speaker 1: were actually just like extreme examples of one membrane theory.
Speaker 1: And this is famous talking gives at University of Southern
Speaker 1: California in ninety five where he points this out and
Speaker 1: he makes this connection, and he has this diagram on
Speaker 1: the slide which is just like all five theories, and
Speaker 1: it just like draws lines between them.
Speaker 3: Is it like a corkboard was the aldest shoveled?
Speaker 1: It's exactly like that. Yeah, it's not very compelling as
Speaker 1: a diagram. And even his explanation is somewhat lacking. You know,
Speaker 1: he doesn't have all the math. He has sort of
Speaker 1: like this leap of intuition. He has some hints that
Speaker 1: these things do connect to each other. It's like a
Speaker 1: new direction forward, and it's sort of like the way
Speaker 1: Fineman worked. You know, Fineman developed QED and he didn't
Speaker 1: work out all the math came later, when like Schwinger
Speaker 1: worked through all the details to prove that Fieman's leaps
Speaker 1: of intuition were correct. Witness sort of similar. He's like
Speaker 1: sees these connections in his brain. He knows that it
Speaker 1: can work, even if he hasn't like actually sat down
Speaker 1: and worked through it all. And so this one talk
Speaker 1: in ninety five inspired what they call the second super
Speaker 1: string Revolution and led to like hundreds and hundreds of
Speaker 1: papers of people working on membranes. The interesting thing is
Speaker 1: that Witten himself wasn't actually sure that membranes were going
Speaker 1: to work. He was like, h it might be membranes,
Speaker 1: it might not be memoranes. I'm not sure. He knew
Speaker 1: that these things were connected, but he didn't want to
Speaker 1: actually call his theory membrane theory, so he just called
Speaker 1: it M theory, and he wrote in his paper quote,
Speaker 1: we will non committally call it the M theory. Leaving
Speaker 1: to the future the revelation of M to membranes, like
Speaker 1: if people really worked through the math and showed that
Speaker 1: these things were two D objects or actually ten D objects,
Speaker 1: then we could call it membrane theory. But until then,
Speaker 1: let's just keep it m theory in case it turns
Speaker 1: out to be like mouse theory or mama theory or
Speaker 1: something else.
Speaker 3: Yeah. No, I mean I like that your hedge in
Speaker 3: your bets. I also like this guy kind of sounds
Speaker 3: like there's this I forgot his name, but I think
Speaker 3: he is like a quote unquote neurosurgeon who kept claiming
Speaker 3: that he could do like head transplants, and his demonstration
Speaker 3: was a bunch of dried spaghetti and a banana to
Speaker 3: show how you could basically like connect all of the
Speaker 3: arteries and spinal cord and everything. I think maybe the
Speaker 3: banana was supposed to be the spinal cord. Anyways, it
Speaker 3: was like a spaghetti banana demonstration, which did not inspire confidence.
Speaker 3: So of course, I think with the physics, when you
Speaker 3: go out on a branch in terms of physics, that
Speaker 3: it's maybe less risky than trusting someone who says they
Speaker 3: can do a head transplant.
Speaker 1: Yeah, so I think Edwintin I wouldn't trust him to
Speaker 1: do a head transplant, but I'm glad that he's around
Speaker 1: and he's helping us figure out the mysteries of quantum gravity.
Speaker 1: And it's really cool that he was able to show
Speaker 1: that these theories are related to each other. You know,
Speaker 1: there are these funny dualities they find where they showed
Speaker 1: that this theory is mathematically equivalent to that theory. You know,
Speaker 1: like this theory if you make it really strong, looks
Speaker 1: like that theory if you make it really weak. It's
Speaker 1: fascinating to show that the theories, even though they have
Speaker 1: again very different sort of mathematical foundations, they really are
Speaker 1: exploring the same concepts because the symbolism, the notation we
Speaker 1: use is really just a way to describe the abstract ideas.
Speaker 1: And so even if you use different notations and different symbols,
Speaker 1: if you can show that the ideas are equivalent, then
Speaker 1: you really have made a connection between them. And it's
Speaker 1: a relief also to think like, well, maybe there is
Speaker 1: a connection, because then we don't have to pick one
Speaker 1: of the theories. We don't have to have a reason
Speaker 1: to choose one. We can just say, oh, they're all
Speaker 1: just special cases of one unifying idea. And in the end,
Speaker 1: that's what physics is trying to do, is come up
Speaker 1: with some unifying, simplifying explanation for everything we see out
Speaker 1: there in the universe.
Speaker 3: I mean, I find it really appealing not having to
Speaker 3: make a decision between like really hard choices. That sounds great.
Speaker 3: Sign me up for physics. Let's take a really quick break,
Speaker 3: and then when we get back, let's talk more about
Speaker 3: membrane theory and how it could tie everything up in
Speaker 3: a bow.
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Speaker 3: Apply, all right. So I was a little bit glib
Speaker 3: about tying everything up in a nice little bow. I
Speaker 3: know that is the desire of physics, and yet it
Speaker 3: seems pretty tricky to do that.
Speaker 1: It is pretty tricky. But along the way we can
Speaker 1: entertain ourselves by amusing notation and making up really weird
Speaker 1: phrases and names for things. So, physics, as everybody knows,
Speaker 1: is very good at using inappropriate and confusing words to
Speaker 1: describe things. And so physicists have taken this phrase membrane
Speaker 1: and try to generalize it to any dimensional surface. So,
Speaker 1: like you know, a membrane is like a two D surface.
Speaker 1: You can imagine like a sheet or like a cell wall.
Speaker 1: It's two dimensions, right, And so physicists don't call that
Speaker 1: a membrane. They call that a two brain. Okay, so
Speaker 1: that they can call a string a one brain, or
Speaker 1: like the point a zero brain.
Speaker 3: That insulting.
Speaker 1: You're a zero brain. Yeah, exactly. Well even worse is
Speaker 1: the general phrase for it. If you have a surface
Speaker 1: in p dimensions, you call it a pea brain.
Speaker 3: That's what I call my dog all the time. I'm like,
Speaker 3: look at you, old pepe brain.
Speaker 1: Yeah, well you didn't realize you're actually giving it a
Speaker 1: vast compliment. You're connecting it to the fundamental theory of
Speaker 1: the universe. Maybe Cookie can reveal something true about reality.
Speaker 3: I look into her eyes, I see these deep pools
Speaker 3: of knowledge. But then it turns out she just had
Speaker 3: to burn.
Speaker 1: Cookie had too many cookies.
Speaker 3: It sounds like, yeah, exactly, So Now I'm confused because
Speaker 3: I kind of got the idea of the membrane being
Speaker 3: like it's not a point, it's not a line. It's
Speaker 3: like a plane, but not necessarily a flat plane, one
Speaker 3: that could be sort of wrapped around different dimensions. So
Speaker 3: I kind of get that. Now we're sort of this
Speaker 3: terminology of zero brain being a point, one brain being
Speaker 3: a string, two brain being a two D surface. What
Speaker 3: is the point of having brain in there? Like as
Speaker 3: a term, like what And I don't mean this like
Speaker 3: in a mean way, just like what purpose is that
Speaker 3: serving in terms of helping with the research or the explanation.
Speaker 1: Yeah, it's a good question. Maybe physicists just like saying
Speaker 1: brain because it does sounds smart, sounds like they're talking
Speaker 1: about their brains. But physicis like to think about different
Speaker 1: versions of ideas, not to be limited by our experience
Speaker 1: of the universe, you know, where we have one dimensional
Speaker 1: objects and two dimensional objects and three dimensional objects. They'd
Speaker 1: like to generalize it and to be opened to other
Speaker 1: dimensions and other scales. And so for example, Edwinton's first
Speaker 1: idea was maybe the way to do this is to
Speaker 1: use two dimensional sheets, which is fascinating to think like, Okay,
Speaker 1: the universe isn't made of points of stuff or even
Speaker 1: lines of stuff, but maybe like sheets of stuff. It
Speaker 1: would be pretty weird if the universe was made of
Speaker 1: two dimensional things the fundamental nature of it, the basic
Speaker 1: building block where sheets, that would be weird. But recently
Speaker 1: people have been making some progress in an alternative version
Speaker 1: of m theory in which the brains are five dimensional,
Speaker 1: so they use five brains, meaning that like, you still
Speaker 1: work in a theory where there are ten spatial dimensions
Speaker 1: in one time dimension, but the fundamental building blocks of
Speaker 1: the universe are not sheets. There are five dimensional objects,
Speaker 1: which is pretty hard to think about and impossible to
Speaker 1: visualize with our three brains.
Speaker 3: Yeah, that's interesting thing because usually the intuitive direction of
Speaker 3: units right of stuff or like building blocks of stuff
Speaker 3: is like you go from simple to more complex, right,
Speaker 3: so like you'd start out with you know, zero dimensions,
Speaker 3: than one dimensions, than two dimensions, than three dimensions, than
Speaker 3: four dimensions, et cetera. Right, and then like as you
Speaker 3: get to the smaller building blocks, the kind of intuitive
Speaker 3: way is like the smaller the building block, the fewer
Speaker 3: the dimensions.
Speaker 4: Right.
Speaker 3: But I think it is really interesting the idea that
Speaker 3: the smallest building block could be something that is actually
Speaker 3: operates among, you know, more dimensions than say we do
Speaker 3: as human consciousness is because that seems, I don't know,
Speaker 3: for some reason, that makes more sense to me than
Speaker 3: like the smallest unit being like a point, even though
Speaker 3: I cannot there is no way I can even begin
Speaker 3: to conceive of five dimensions without sounding like I'm high
Speaker 3: on Joe Rogan.
Speaker 1: I think you're right, though, and I think the lesson
Speaker 1: there is the universe is filled with surprises. You know.
Speaker 1: We set up this question with we have a puzzle
Speaker 1: about the fundamental nature of reality. Is it quantum mechanical?
Speaker 1: Is it general relativistic? Is this something new and weird
Speaker 1: and different? And we don't have an answer yet, But
Speaker 1: this line of investigation building strings into membranes into p
Speaker 1: brains is suggesting that we've been thinking about it wrong
Speaker 1: in terms of tiny little objects that actually at the
Speaker 1: foundation of the universe, the basic level of reality, the
Speaker 1: intellectual firmament that we can finally reach, might be built
Speaker 1: out of complex objects, objects with five dimensions to them,
Speaker 1: or even two dimensions. And that's the kind of revelation
Speaker 1: we're looking for, you know, that's exactly the hope that
Speaker 1: the math points us to structures that tell us something
Speaker 1: about what's actually happening out there in reality. And in
Speaker 1: a way, that's a surprise because I don't expect our
Speaker 1: intuition to correctly guess how the universe works. I expect
Speaker 1: it to be a surprise. It would be quite disappointing
Speaker 1: if the universe was a certain way and we were like, oh, yeah,
Speaker 1: that makes sense. Instead, I want that moment where we're like, oh, wow,
Speaker 1: the universe actually works in this weird way, how could
Speaker 1: that possibly be? And then it requires like a reworking
Speaker 1: of your mental model to incorporate that. But that brings
Speaker 1: you more in aligned with the way the universe actually works.
Speaker 1: And that's kind of the whole goal of science, right,
Speaker 1: is to align our brains with the workings of the universe,
Speaker 1: not just our silly, clueless, primitive guesses about how the
Speaker 1: universe might work.
Speaker 3: So, if it was up to me, I would just
Speaker 3: hazard a guess that the universe is made out a
Speaker 3: little worms, man, just tiny little worms.
Speaker 1: I see, So that's your worm brain theory of the universe,
Speaker 1: my brain theory you and rfkgu.
Speaker 3: Yeah, I should run for president and me and my
Speaker 3: worms know how to run this country.
Speaker 1: Terrence Howard, all right, well, thanks for coming along on
Speaker 1: this crazy mental journey down into the fundamental nature of
Speaker 1: the universe to think about weird quantum objects, also obeying
Speaker 1: the rules of gravity and revealing that the universe is
Speaker 1: made out of building blocks that we do not yet understand,
Speaker 1: but they might require one brains, two brains, or p
Speaker 1: dimensional pea brains.
Speaker 3: Thank you for helping me understand that the universe is
Speaker 3: not made out of tiny violence. That really helps.
Speaker 1: It's only possible because your brain is not a banana.
Speaker 1: All right, Thanks very much everybody, and tune in next
Speaker 1: time for more science and curiosity. Come find us on
Speaker 1: social media where we answer questions and post videos. We're
Speaker 1: on Twitter, This, Org, Instant, and now TikTok. Thanks for listening,
Speaker 1: and remember that Daniel and Jorge Explain the Universe is
Speaker 1: a production of iHeartRadio. More podcasts from iHeartRadio, visit the
Speaker 1: iHeartRadio app, Apple Podcasts, or wherever you listen to your
Speaker 1: favorite shows. When you pop a piece of cheese into
Speaker 1: your mouth, you're probably not thinking about the environmental impact,
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