Speaker 1: One thing that I really love about physics is that
Speaker 1: sometimes the laws of physics don't just work, they're actually pretty.
Speaker 1: What do you mean physics can be pretty? You know?
Speaker 1: I thought physics and science was like a hard hitting
Speaker 1: objective thing, you know, human endeavor. Absolutely, we got big tasks.
Speaker 1: We want to understand the universe and makes sense of it.
Speaker 1: But sometimes we come up with an idea, something that
Speaker 1: just looks beautiful, something which is has an innate elegance
Speaker 1: to it. You mean, like you'd see a theory walking
Speaker 1: down the road and you'd be like, oh, man, that
Speaker 1: that theory hasn't going on. Yeah, there's some sexy the
Speaker 1: curves in that theory. You mean like graphs though, right,
Speaker 1: Like that that kind of occurs, right, that graph is
Speaker 1: a nice curve to look those peaks. And one of
Speaker 1: the most controversial theories of all time, one of the
Speaker 1: ones that gets people up in arms, is also one
Speaker 1: that's probably survived because it's so beautiful. An alogot isn't
Speaker 1: the theory of attraction. No, it's a theory that was
Speaker 1: once described as a piece of twenty first century physics
Speaker 1: that had fallen by accident into the twentieth century. So
Speaker 1: it's a future Babe, future baby exactly. Hi. I'm Orge,
Speaker 1: I'm a cartoonist and I'm Daniel. I'm a particle physicist,
Speaker 1: and we are the authors of the book We Have
Speaker 1: No Idea, which talks about all the things we don't
Speaker 1: know about the universe and how we might hope to
Speaker 1: one day understand them. Yeah. So, welcome to our podcast.
Speaker 1: Daniel and Jorge explained the universe, in which we take
Speaker 1: everything and anything in the universe and try to explain
Speaker 1: it to you in a way that makes sense and
Speaker 1: hopefully makes you laugh to be on the program. We're
Speaker 1: going to talk about, Oh, string the that's right, string theory.
Speaker 1: And this is a question that we've been getting from listeners.
Speaker 1: We ask people, please send in your request for topics,
Speaker 1: and maybe more than fifty percent of the request work.
Speaker 1: Can you explain string theory? What is stringth theory? Talk
Speaker 1: about string theory more than yeah, and it's fascinating. It's
Speaker 1: because string theory really is a part of sort of
Speaker 1: cultural zite guys. It's like an idea that people know
Speaker 1: exists even if they don't understand it. It's a big
Speaker 1: part of that show The Big Bang Theory, right, like
Speaker 1: the people in that show there they supposedly study string theory.
Speaker 1: I don't know. I don't watch that show me neither,
Speaker 1: but that's what I've been told. Your cultural advice expert
Speaker 1: has told you that this is a culturally relevant thing. Well, yeah,
Speaker 1: it's it's something people have heard about. Well have you
Speaker 1: heard about string theory before you started spending your time
Speaker 1: talking to physicists? Know, yeah, I've heard about it. You know.
Speaker 1: It's one of these things that you hear a lot about.
Speaker 1: It's these like crazy theory about the universe, but it's
Speaker 1: really and you know, you hear certain things about it, like, oh,
Speaker 1: everything is made out of strings, but you don't really
Speaker 1: kind of know what it is and what does it
Speaker 1: mean for things to be strings. You're a very visual person.
Speaker 1: What image do you get in your head if I
Speaker 1: tell you everything is made out of strings? Do you
Speaker 1: get like a universe an idea of like a universe
Speaker 1: where everything is crocheted out of yarn? Or how does
Speaker 1: it work? In your head? I would to just ask
Speaker 1: what are those strings made out of? Right? Right? Of course?
Speaker 1: So you are a physicist at hard right, because every
Speaker 1: question just leads to the next question. That's right, beautiful physicists,
Speaker 1: a hard supermodel on the outside. No comment. Um, but
Speaker 1: I thought it was an interesting question to tackle because
Speaker 1: it's something everybody has heard about, but very few people
Speaker 1: actually understand. I think that's why people wanted us to
Speaker 1: talk about, is saying, can you make this not just
Speaker 1: something we have heard this phrase, but something where we
Speaker 1: can know what it means and gets an insight into
Speaker 1: why people are spending their time doing it. Right. Yeah, So,
Speaker 1: as usual, we went out into the street and ask
Speaker 1: do you know what strength theory is? Yeah? So before
Speaker 1: you hear these answers, think for a moment, could you
Speaker 1: define strength theory? Do you know what it is and
Speaker 1: why it's persisted for so long. Here's what people who
Speaker 1: I asked had to say. Um, No, I have no
Speaker 1: idea what that is. No, I do not. I've heard
Speaker 1: of it. My only way of Big Bang theory Okay,
Speaker 1: I don't know. I'm sorry. The connectedness of Adams and
Speaker 1: sub atomic particles Okay, it's something that Sheldon worked on. Yes, Okay,
Speaker 1: So first of all, it's kind of interesting because you
Speaker 1: normally you go out into your university campus to ask people,
Speaker 1: but this time you went somewhere different. Yeah, that's right.
Speaker 1: You see, Irvine was closed for a holiday, so instead
Speaker 1: I went to the mall here in Irvine, the Spectrum,
Speaker 1: and I asked a bunch of random strangers, um questions
Speaker 1: about science. And again I was struck by how many
Speaker 1: people were willing to answer my questions. I thought people
Speaker 1: would say, who are you? Go away security security? Right?
Speaker 1: Maybe they sense a certain beauty about you, Daniel, You're like,
Speaker 1: who is this beautiful specimen of a person? Know? Who is?
Speaker 1: Apparently I just don't look very threatening, you know. Um,
Speaker 1: I look like I could could get knocked to a
Speaker 1: religious a passing breeze or something. Um. So everybody was
Speaker 1: willing to engage, which was awesome, and people had some
Speaker 1: pretty fun ideas, and everybody had heard of it. Nobody
Speaker 1: had said hell what, and your other speculation was correct.
Speaker 1: Some people had heard of strength theory specifically because of
Speaker 1: the Big Bang theory. So thank you Big Bang Theory.
Speaker 1: You've mined all of this juice from nerd culture and
Speaker 1: you have actually communicated something to the public. And congratulations.
Speaker 1: Nobody understands what string theory is, but they do understand
Speaker 1: that it is a theory. Well, I think that show
Speaker 1: doesn't even try to explain it, right, They almost use
Speaker 1: it for the opposite effect, Like, let's depict our characterist,
Speaker 1: this impenetrable, unrelatable genius that speaks gobbling Google, so we'll
Speaker 1: just having to talk about strength theory and that nobody
Speaker 1: and nobody's going to understand that. So it's it's likely.
Speaker 1: So you're saying string theory represents the impenetrability of physics.
Speaker 1: I think it's more important to explain these things to
Speaker 1: people rather than just toss these words around and try
Speaker 1: to intimidate people. So yeah, I think that's what I mean.
Speaker 1: It's like they use it to intimidate people about physics, Yeah,
Speaker 1: when physics is nothing but warm and cuddly and just
Speaker 1: wants to explain the universe to you. Man, there's nothing
Speaker 1: intimidating about physics, right. It's about revealing secrets and giving
Speaker 1: understanding and insight and appreciating beauty. And that's the thing
Speaker 1: about string theory is it doesn't just potentially explain a
Speaker 1: lot of things. It also offers some elegance, some gorgeousness,
Speaker 1: like a peak into what nature is doing underneath. Because
Speaker 1: you know, you can have ugly theories and you can
Speaker 1: have elegant theories, you know, and you might ask the difference,
Speaker 1: like how what is the difference? Well, I can ask
Speaker 1: you the same question about art, right, Like I look
Speaker 1: at the Kendinsky and I say, hey, that's beautiful, and
Speaker 1: somebody else says whatever, I could do that in an afternoon.
Speaker 1: It's garbage. It's subjective, right, you can't. It's like the
Speaker 1: whole question of what is beauty is something that's very
Speaker 1: difficult to nail down. So you shouldn't judge a painting
Speaker 1: by the same metric you used to judge of physics theory. Um.
Speaker 1: And you know, two physicists can disagree about what theory
Speaker 1: is pretty and what theories ugly. So it's it's totally subjective.
Speaker 1: It's not an objective fish like a you know, I
Speaker 1: like this kind of theory. I like that kind of theory. Yeah,
Speaker 1: Like you know, I like theories with handcuffs in the
Speaker 1: midstet of strings, right, like my handcuff theory of the universe.
Speaker 1: That's where that's where you're going theories or yeah, okay,
Speaker 1: So let's break it down for people. What is string theory? Right?
Speaker 1: So string theory is basically is the idea that the
Speaker 1: smallest elements of matter with things that things are made
Speaker 1: out of are not points, not particles, but instead their lines,
Speaker 1: their strings, strings of what strings of basic universe stuff? Right, So,
Speaker 1: like the electron is is not like a little ball,
Speaker 1: and we know it's like a quantum object, which is
Speaker 1: like a point with some kind of probability. But you're
Speaker 1: saying if you zoom in even more, maybe you would
Speaker 1: see a little squiggle there. Yeah, And the sort of
Speaker 1: two ideas there. One is what is the most basic element?
Speaker 1: And the second is is their most basic element? So
Speaker 1: this assumes there is a most basic element. You know
Speaker 1: that you you look at something next to you, pick
Speaker 1: up in the nearest object you have, you know, maybe
Speaker 1: it's an apple, maybe it's a platypus, maybe it's a
Speaker 1: you know, I don't know what, and and think about
Speaker 1: what it's made out of. It's made of molecules, right,
Speaker 1: Tear those apart, you get atoms. Tear those atoms apart,
Speaker 1: you get protons and neutron's electrons. Tear those apart, you
Speaker 1: get quarks. Right, and you could keep going and eventually
Speaker 1: you get two smaller and smaller particles. Right. The question
Speaker 1: is do you ever get to the smallest particle. Right,
Speaker 1: that's one question. Is there a smallest thing? And we
Speaker 1: covered that in a whole podcast, but here we're just
Speaker 1: gonna assume that there is. Right, at some point, you
Speaker 1: get down the most basic thing where you're not allowed
Speaker 1: to ask what it's made out of because it's made
Speaker 1: out of the most basic universe stuff. It's like the
Speaker 1: one circle on a lego set. It's like, you can't
Speaker 1: get any smaller than that. That's right, it's the unit exactly,
Speaker 1: And that's you might feel like that, that's frustrating. Why
Speaker 1: can't I ask what it's made out of? You know?
Speaker 1: But it's also not frustrating because it would be the answer.
Speaker 1: I mean, if you actually got there and you said, look,
Speaker 1: everything in the universe is made out of this one
Speaker 1: basic thing. That's a deep insight, right, that's what we're
Speaker 1: going for. That's the day we wish for that we
Speaker 1: peel back a layer of reality and see everything is
Speaker 1: made out of this thing, because then you can ask
Speaker 1: why this thing? What does that mean? Oh? I see?
Speaker 1: So string theory is saying that everything electrons course, eventually,
Speaker 1: if you break them down, you'll get to this one
Speaker 1: type of string. That's right. We think of things being
Speaker 1: made of particles, We think of them as tiny dots
Speaker 1: right in space. But string theory says they're not dots,
Speaker 1: their lines okay, and they're they're these loops and wiggles
Speaker 1: instead of being dots. And then everything is made out
Speaker 1: of these strings. And you might ask, well, how can
Speaker 1: you get different kinds of particles, for example, out of
Speaker 1: one kind of string? Right, And the idea there is
Speaker 1: that the strings can vibrate, the strings can wiggle, right,
Speaker 1: the reverberations in the string just like you know a
Speaker 1: rubber band or a string. Is it like an actual vibration,
Speaker 1: like it goes up and down or is it just
Speaker 1: like the different shapes you can make with a string. Oh,
Speaker 1: I see No, it's actual motion of the string. Yeah,
Speaker 1: And so it's different, different vibrational modes. So they get
Speaker 1: excited and they can get into this state or that state.
Speaker 1: As the string vibrates in different ways, it makes different particles.
Speaker 1: So some tiny particle calling it's an electron, for example,
Speaker 1: is actually a string vibrating this way, and a cork
Speaker 1: is a string vibrating the other way. And the neutrinos
Speaker 1: a string vibrating a third way, so the same thing
Speaker 1: with different vibrations can appear as different particles. Okay, so
Speaker 1: it's not like different strings and a guitar. That's not
Speaker 1: what we're talking about. We're talking about one string. It's
Speaker 1: like a one string guitar and just the different ways
Speaker 1: in which it can vibrate that gives rise to all
Speaker 1: the different stuff we see in the universe exactly. And
Speaker 1: like a guitar, you can pluck the string differently and
Speaker 1: you can get different notes, right, you can if based
Speaker 1: on how fast it's vibrating and you know where you
Speaker 1: put your finger in the end, you can get different
Speaker 1: notes out of the same string. And it's key here,
Speaker 1: that's one string, right, it's a single string. Because we're
Speaker 1: to explain everything in the universe in terms of one object.
Speaker 1: So we're trying to explain how you get all this
Speaker 1: complexity in terms of one thing. And that's the answer
Speaker 1: from string theory is that the string has different modes
Speaker 1: to it to drink, can do different things. And you know,
Speaker 1: you might think that's sort of weird, Like I expect
Speaker 1: stuff if it's all made of the same thing, to
Speaker 1: be the same thing, right, Like if everything is made
Speaker 1: of the same stuff. Why is this red and that blue?
Speaker 1: And this tastes delicious and this tastes terrible, right, And
Speaker 1: it comes from the way it's vibrating. It's kind of
Speaker 1: like maybe light. You know, a light is just made
Speaker 1: out of one thing, photons, but depending on the frequency,
Speaker 1: then it's different colors. Yeah, exactly. And the way things
Speaker 1: move and vibrany can totally affect the way they we
Speaker 1: perceive them. You know, think about for example, water, right,
Speaker 1: water is made out of water molecules, but so is ice,
Speaker 1: and so is steam. Right, They're made out of the
Speaker 1: same thing, but we feel them, we experience them very
Speaker 1: differently because of the way they're moving, right, steam and
Speaker 1: liquid water. How the water particles moving more than an ice, right,
Speaker 1: And so it's the most into those particles that generates
Speaker 1: the macroscopic qualities that we used to define it. So
Speaker 1: the things we used to define the electron and things
Speaker 1: we used to define a quirk actually come just from
Speaker 1: the vibrations of these strings. Again according to this theory. Okay,
Speaker 1: so so then, but then my question is still, what
Speaker 1: are these strings made? Is it just like made out
Speaker 1: of universe I told you? Or hey, you're not let
Speaker 1: to ask once we get down to the lowest level,
Speaker 1: no more questions. No, but you know what I mean,
Speaker 1: like is it like a like a physical string or
Speaker 1: just like a mathematical string? Do you know what I mean?
Speaker 1: Like is prepare for philosophical detour here, like what's actually
Speaker 1: vibrating like universe stuff? Yeah? Yeah, Well, because I still
Speaker 1: look in the end, all physics theories are just models. Right,
Speaker 1: you gonna ask the question is this really happening or
Speaker 1: is this just a mathematical model? In my head, I
Speaker 1: used to do calculations and predict the results of experiments. Boom.
Speaker 1: That is a big philosophical question, right, and there's no
Speaker 1: way to answer that. So we think of these things
Speaker 1: as models in our head reflect reality. Okay, you know
Speaker 1: the top cork doesn't exist or not? Or is it
Speaker 1: is a calculation a model in my head? We could
Speaker 1: you know, smoke banana peels and talk about that for
Speaker 1: a long time without making any progress. So this model
Speaker 1: is just asking me to imagine that the most fundamental
Speaker 1: thing at the universe are these little strings. They can
Speaker 1: vibrate in different ways, but then these trains can move
Speaker 1: around and they can't be cut into pieces. Right, you
Speaker 1: can't get anything smaller than a string. It's the most
Speaker 1: basic unit. Like, there's something about the stuff of the
Speaker 1: universe that is just you can't vibrate or do things
Speaker 1: shorter than these little strings. Yeah, exactly. Or thinking about
Speaker 1: it from the other direction, you know, how do you
Speaker 1: make a universe? Well, you start with a huge pile
Speaker 1: of tiny strings, and then the way those strings interact
Speaker 1: gives you all sorts of interesting structure. But that's what
Speaker 1: you start from, right, that's the universe's initial condition is
Speaker 1: like a huge pile of strings. And these trains can
Speaker 1: move around space. Yeah, they move and they interact with
Speaker 1: each other, right, and that's where all interesting stuff. But
Speaker 1: are these related to the quantum fields? How does that
Speaker 1: really fields? Yeah? So everything we'd be built out of
Speaker 1: these strings, including all the particles and all the forces.
Speaker 1: And that's actually why string theory is so popular because
Speaker 1: string theory, we think, can explain some of the mysteries
Speaker 1: of quantum fields and some of the mysteries of how
Speaker 1: to bring gravity into the fold and describe it in
Speaker 1: terms of a quantum field. So the short answer to
Speaker 1: your question is, all the quantum fields arise from these
Speaker 1: string interactions. All these fields, all these particles just come
Speaker 1: from this one string guitar being plugged the different frequencies.
Speaker 1: That's right. So while you're imagining a single string guitar
Speaker 1: of the universe, let's take a quick break. All right. So, um,
Speaker 1: that's that's a crazy concept to ask people to digest.
Speaker 1: But let's assume that that's the theory. Um, why who
Speaker 1: came up with this and why do we think it's
Speaker 1: a good theory about the universe? Yes, the string theories
Speaker 1: had a lot of people contribute to it. It's sort
Speaker 1: of an old theory that started out trying to explain
Speaker 1: something else and then was tossed aside when it didn't work,
Speaker 1: and it was later picked up again, um and reused
Speaker 1: two as a theory of everything. And this sort of
Speaker 1: idea of string theory is to take a different approach
Speaker 1: to solving this question of what is the universe made
Speaker 1: out of? As an experimentalist, my approaches take something concrete,
Speaker 1: break it into pieces, gets smaller and smaller and smaller.
Speaker 1: You know, as you discover new stuff, you're revealing secrets
Speaker 1: to the universe, and just keep going until you get
Speaker 1: to the smallest bit. Sort of via top down approach, right,
Speaker 1: This idea is different. This is sort of a bottom up.
Speaker 1: They say, let's just start at the very bottom. Let's
Speaker 1: go to the most basic element and try to explain
Speaker 1: the universe from the start. You know, if a hypothesize
Speaker 1: the universe has made of strings, can we put them
Speaker 1: together in a way that explains the universe and describes
Speaker 1: everything we see around us? But I guess how did
Speaker 1: someone even think of using strings? How do you make
Speaker 1: a lot of things out of one thing? And a
Speaker 1: little ring that vibrates different ways is one way to
Speaker 1: get a lot of things out of one simple thing?
Speaker 1: Is that kind of the origins of it? Yeah, exactly,
Speaker 1: you should imagine. Physicists are basically random, terrible idea generators,
Speaker 1: and most of those just don't work. So at some
Speaker 1: point somebody's like fed up with thinking about the universe
Speaker 1: in terms of particles, and they're like, well, what if
Speaker 1: they're not you know, what if they're not dots, Let's
Speaker 1: just try it with lines. Does that work? You know?
Speaker 1: And basically every idea that you can imagine, somebody has
Speaker 1: tried to make that work as a theory and everything,
Speaker 1: and usually given up after about two seconds because the
Speaker 1: theory of everything based out of little puppies or whatever
Speaker 1: doesn't work. It's very hard to make that put together.
Speaker 1: But like they maybe they say, what if there's just
Speaker 1: one particle that makes up everything, how would you how
Speaker 1: would you explain how this one particle can turn into
Speaker 1: other things? And so that's kind of difficult maybe, But
Speaker 1: a string, you can imagine it vibrating or moving in
Speaker 1: different ways to give rise to different particles, right, yeah, exactly.
Speaker 1: And people were playing with it and like, what can
Speaker 1: we do with this? And they try, like I said,
Speaker 1: they try to use it to solve other problems. Specifically,
Speaker 1: they try to under stand the strong nuclear force using strings,
Speaker 1: and it didn't work. And then later somebody else said, Hi,
Speaker 1: I heard about this idea of strings. I wonder if
Speaker 1: I can use that to solve this other problem, which
Speaker 1: is why can't we get gravity to play well with
Speaker 1: the other forces. You know, if you want to understand
Speaker 1: the way the universe works, you have to try to
Speaker 1: explain everything in terms of one theory, right, to bring
Speaker 1: it all together into a single explanation, because that's a
Speaker 1: big problem right now in physics, right, Like it's like
Speaker 1: marrying quantum physics with gravity. That's right. It's a marriage
Speaker 1: we've been trying to arrange forever, but the two participants
Speaker 1: just do not want to do not want to play
Speaker 1: along exactly. They don't pressure. Yeah, So we have these
Speaker 1: sort of two towering achievements of physics. On one hand,
Speaker 1: quantum mechanics, right, a revelation about a hundred years old.
Speaker 1: It tells us that the universe is very different from
Speaker 1: the way we thought it was, that there's uncertainty, that
Speaker 1: there's fuzziness, a limited amount of knowledge we can actually
Speaker 1: obtain about the universe. And it's most specifically that the
Speaker 1: universe is quantized, it's broken up into discreete little chunks.
Speaker 1: And on the other hand, we have gravity and general relativity,
Speaker 1: which is an incredibly successful theory that describes the motion
Speaker 1: of planets around stars and black holes and all sorts
Speaker 1: of crazy stuff and time dilation in the way space
Speaker 1: and time are connected, all this incredible stuff. But it
Speaker 1: assumes the universe is not quantum mechanical, right. It assumes
Speaker 1: that that energy can be subdivided into arbitrarily small bits,
Speaker 1: and you can have an infinite number of locations and
Speaker 1: an infinite amount of information. Right, And so the two
Speaker 1: theories are not consistent, and most of the time they're
Speaker 1: talking about different stuff so they don't overlap. Sometimes, like
Speaker 1: when you're talking about a black hole, then the two
Speaker 1: give you very different stories. Okay, so, how is strength
Speaker 1: theory able to marry gravity and quantum mechanics? Right, So
Speaker 1: that is exactly the right question. How does string theory
Speaker 1: allow us to bring together quantum mechanics and gravity? Well
Speaker 1: to understand that, you really have to understand why we
Speaker 1: failed without string theory. And the problem is that when
Speaker 1: you bring together quantum mechanics and gravity, you get lots
Speaker 1: of infinities. Right. A theory doesn't work when it can't
Speaker 1: predict the results of experiments. So if you ask a
Speaker 1: theory what happens when I smash two particles together, it
Speaker 1: should give you a reasonable answer. If the answer is infinity,
Speaker 1: or you know, nothing will happen or something, then it
Speaker 1: doesn't make any sense. It has to give physical answers,
Speaker 1: and infinity is not a physical answer. The problem is
Speaker 1: when you try to bring gravity into quantum mechanics, you
Speaker 1: get lots of these infinities. And the infinities come because
Speaker 1: of the point particles, because you're trying to treat these
Speaker 1: objects as if they're just dots in space, and that
Speaker 1: leads to lots of craziness. You know, how do you
Speaker 1: have mass in a tiny little dot in space that
Speaker 1: has infinite density? Right now? We have lots of other
Speaker 1: theories that do play well with quantum mechanics. Electromagnetism, for example,
Speaker 1: very happily married with quantum mechanics. And the reason that
Speaker 1: works is that we have tricks to hide those infinities.
Speaker 1: We can bundle up those infinities that that pop up
Speaker 1: in the from the point particles in various other ways
Speaker 1: mathematical tricks. Those tricks don't work for gravity because gravity
Speaker 1: is very different from the other forces. The strength of
Speaker 1: the force grows with the energy of the object, right,
Speaker 1: So in this case, when an object has more and
Speaker 1: more energy, it feels more and more gravity, right because
Speaker 1: gravity is proportional amount of energy in an object. So
Speaker 1: the typical tricks we use to hide those infinities under
Speaker 1: the rug that works for quantum electrodynamics doesn't work for
Speaker 1: gravity when we try to do quantum gravity. So how
Speaker 1: does string theory to solve that problem? Simple? It just
Speaker 1: says there are no points. It says at the smallest scale,
Speaker 1: you don't have to worry about dealing with gravity a
Speaker 1: tiny points because there are none because that it's smallest scale.
Speaker 1: The universe is not made of points but strings, and
Speaker 1: so it's a nice way to sort of circumvent that problem.
Speaker 1: And that's why string theory can bring together quantum mechanics
Speaker 1: and gravity so nicely. And I got people excited, and
Speaker 1: that's where the beauty was. People were like, wow, and
Speaker 1: it's beautiful. There's like these strings floating around. You get
Speaker 1: these membranes and its It seemed really cool to people.
Speaker 1: So you said something interesting, which was that people thought
Speaker 1: that dringth theory was beautiful and elegance. So can you
Speaker 1: try to explain like why people thought that, Like is
Speaker 1: it simple or is it just it's so open ended
Speaker 1: or it just seems to be working or it doesn't
Speaker 1: fall into the ugliness of other theories. I think people
Speaker 1: just have fun working with it, you know. I think
Speaker 1: it's I think it stimulates people's imaginations can have fun,
Speaker 1: and physicists can have fun. Yeah, and you know, when
Speaker 1: you do string theory, you write down these diagrams, and
Speaker 1: instead of these diagrams being lines with swils, that diagrams
Speaker 1: are like loops, and they have sheets to and to
Speaker 1: connect them, you know, membranes, and you get to think
Speaker 1: about these high dimensional surfaces and people have a lot
Speaker 1: of fun with them, and it's been so invigorating for
Speaker 1: physicists that's actually led to a lot of good results
Speaker 1: just in mathematics, Like mathematicians have learned about things from
Speaker 1: the things that physicists have done while exploring its string theory,
Speaker 1: and so it's it's stimulated. The whole field of mathematics
Speaker 1: and mathematics is about the beauty and interconnectedness of numbers.
Speaker 1: They don't care if it actually just scribes anything in
Speaker 1: the real world, right, It's about these abstract ideas and
Speaker 1: how they come together. And one of the lead physicists
Speaker 1: who works on string theories name is Ed Witten. He
Speaker 1: won what's basically the Nobel Prize for math, which is
Speaker 1: the Field Medal, which is even harder to win than
Speaker 1: the Nobel Prize because they only give it every two years,
Speaker 1: and he's a physicist, and he won the top prize
Speaker 1: in mathematics for advances in string theory, which tells you that,
Speaker 1: like there's a huge amount of mathematical machinery that's been
Speaker 1: invented here. And these folks they love it like it's
Speaker 1: a it's fascination for them. It's a there's a deep
Speaker 1: pleasure in manipulating these equations and in thinking about it. Oh,
Speaker 1: usually it's the other way around, Like usually you guys
Speaker 1: have to come over the theory and convince mathematicians that
Speaker 1: this is something fundamental here. It seems to be coming
Speaker 1: from the other way. It's like, here's something that even
Speaker 1: mathematicians I think might be fundamental about the universe. Well,
Speaker 1: I don't know if mathematicians think it's fundamental about the universe.
Speaker 1: They just think it helps solve interesting problems. They're like, oh,
Speaker 1: this is a cool tool. It can solve some problems
Speaker 1: in math, or it gives us a new way to
Speaker 1: think about mathematical problems. You know, And anytime you get
Speaker 1: a new tool, it's fascinating. And you imagine, for example,
Speaker 1: you're an artist and somebody invents a new musical instrument
Speaker 1: and you're like, oh, cool, what can I use this for.
Speaker 1: I can invent a new kind of music. I can
Speaker 1: have a new kind of rhythm or a new kind
Speaker 1: of song. Or in the same way, you create a
Speaker 1: new physics theory, a new basic object you get to
Speaker 1: play with. It's exciting. He gives you things to play
Speaker 1: with and ideas to try. And so like this is
Speaker 1: a said, hey, look I have a one string guitar,
Speaker 1: and were like, whoa, I can play the whole universe
Speaker 1: on that thing. But you know, string theory has a
Speaker 1: lot of people who love it and adherence and a
Speaker 1: lot of people in departments who are working on it.
Speaker 1: But there are also a lot of people who don't
Speaker 1: like string theory. It's got sort of a backlash as well.
Speaker 1: Any you know, you've made it as a physics theory
Speaker 1: when you have haters, right, physics haters physics. All right,
Speaker 1: let's get into it, but first let's take a quick break.
Speaker 1: Al Right, So, strength theory has its haters, people who
Speaker 1: don't think it's all that or who think it might
Speaker 1: be wrong, or maybe it's not all that beautiful. So
Speaker 1: what are some of the arguments against string theory. Yes,
Speaker 1: so I would say there's really two categories of attacks
Speaker 1: people make against string theory. One is there's just too
Speaker 1: many of them, and the other is that we can't
Speaker 1: test it. Too many stringth theories, too many string theories.
Speaker 1: It's not a singular concept, you know, stringth theory, it's
Speaker 1: actually string theories. I remember loctrology, string theories, string theories.
Speaker 1: There are a lot of There are a lot of
Speaker 1: these things. There's lots of ways that you can put
Speaker 1: it together, lots of different ways you can shape the string,
Speaker 1: and lots of ways you can have them interact with
Speaker 1: each other. And um, you know we were saying earlier,
Speaker 1: you'd like a simple theory. You'd like to make your
Speaker 1: choices for how you build the theory, not the arbitrary
Speaker 1: will be forced by the mathematical construction, you know, like
Speaker 1: why is there a three here? It's the only way
Speaker 1: that it works. So we have a theory where there
Speaker 1: are lots of ways it could work. Then you have
Speaker 1: a question like which way do we choose? And that's
Speaker 1: the problem with string theory. There's lots of ways to
Speaker 1: build one. They all have the same basic idea, right,
Speaker 1: which is the universe made out of little strings and
Speaker 1: everything comes out of the way vibrates. But you're saying,
Speaker 1: there's a lot of options after that basic concept, like
Speaker 1: how do they how do these strings interact or what
Speaker 1: do they sound like? Or exactly? Um, and the reason
Speaker 1: is that you can't make string theory work in four dimensions. Right,
Speaker 1: Our universe that we experience has four dimensions, is three
Speaker 1: dimensions of motion x, y z and then one dimension
Speaker 1: of time, So we live in four dimensions. But strings,
Speaker 1: for they get them, to get them to have these
Speaker 1: mathmatical properties that we want to unify quantum mechanics and gravity,
Speaker 1: they have to operate in more dimensions for the math
Speaker 1: works like the dimension in which they're vibrating kind of thing,
Speaker 1: and then are four just the ones where it's moving
Speaker 1: around it. In some theories, yes, they vibrate in those
Speaker 1: other dimensions, and that changes how we see them in
Speaker 1: these dimensions. But there's a lot of different kinds of
Speaker 1: string theory, and so that's not a general statement. And
Speaker 1: some of them are eleven dimensional theories and some of
Speaker 1: them are twenty six dimensional theories. Right, And so the
Speaker 1: ideas these strings are vibrating these other dimensions, but we
Speaker 1: don't see those other dimensions, like I don't I can't
Speaker 1: move in twenty six dimensions. How can you say that
Speaker 1: your theory, which has twenty six dimensions explains my four
Speaker 1: dimensional universe. So to answer that, to solve that problem.
Speaker 1: They have to roll up those other dimensions and tuck
Speaker 1: them away and make them small, to make them like hidden,
Speaker 1: kind of like too small to the experience in our
Speaker 1: everyday lives. Yeah, which is why you don't see them
Speaker 1: or experience them or see them in physics experiments. And
Speaker 1: there's lots of different ways to do that, because twenty
Speaker 1: six dimensions a lot of freedom, and so you can
Speaker 1: organize that in lots of different ways, and there's you
Speaker 1: can make choices, and you have to make choices. How
Speaker 1: do you take this twenty six dimensional theory boil it
Speaker 1: down to four dimensions. Turns out there's like ten to
Speaker 1: the five hundred different ways to organize that, which is
Speaker 1: a lot of different choices, different flavors of stringth theory,
Speaker 1: or different choices you can make different flavors. You went
Speaker 1: to the ice cream shop for string theory, and they
Speaker 1: have ten to the five hundred different flavors. And if
Speaker 1: you want a sample of each one, you're not even
Speaker 1: going to order. You're gonna be full before you leave.
Speaker 1: Ten to the five. Thing about what that number is?
Speaker 1: Right for scale, there's like ten to the ninety particles
Speaker 1: in the universe, So it's the problem in strength theories
Speaker 1: said all of these strength theories would work. Is that
Speaker 1: kind of the problem yes, um, yeah, And that thing
Speaker 1: that gets into the second criticism, which is, you know,
Speaker 1: can we test string theory. We can only see the
Speaker 1: universe down to a certain scale so far. I mean
Speaker 1: we use large the large Hadron collider, and we smash
Speaker 1: particles together, we get down to distances of like ten
Speaker 1: to the minus twenty meters, right, really really small distances.
Speaker 1: So all the string theories, the ten of the five
Speaker 1: hundred string theories, they all can explain things that happened
Speaker 1: that we've seen so far, all of them right. To
Speaker 1: distinguish between them, we need to look much deeper. Oh
Speaker 1: I see. So like mathematically there's a whole bunch of
Speaker 1: possible ones, but experimentally we can't test which one is
Speaker 1: right exactly. And that's the problem because strings, if they exist,
Speaker 1: we think they're about ten to the minus thirty five
Speaker 1: meters in size, which is super duper tiny. And maybe
Speaker 1: you're thinking, I don't know, we can see down to
Speaker 1: ten to the minus twenty meters. How much smaller is
Speaker 1: tend of the minus thirty five they're basically it's just
Speaker 1: tiny it's much much smaller. It's ten to the fifteen
Speaker 1: times smaller, right, And to give you a sense of scale,
Speaker 1: like the solar system is about ten to the fifteen
Speaker 1: meters across. It's a big difference, you know, if you
Speaker 1: could see only solar system size stuff, where if you
Speaker 1: could see like one meter size stuff. So strings are
Speaker 1: really really tiny, which is why we're not anywhere close
Speaker 1: to seeing them. Doesn't the theory have also ways in
Speaker 1: which it kind of builds up to our world? It does,
Speaker 1: but you can't distinguish between those theories. Um, they all
Speaker 1: predict the same thing, and they're also competing theories. You know,
Speaker 1: there's a theory of quantum loops you not strings, but loops, right,
Speaker 1: that also explains quantum gravity. And we can't distinguish between
Speaker 1: the various string theories and this theory of quantum loops
Speaker 1: because we can't see small enough yet, right. And so
Speaker 1: it's a criticism of this whole bottom up approach. Right, Yeah, cool,
Speaker 1: you started at the bottom, but you haven't built up
Speaker 1: far enough for us to test your theory. Is this
Speaker 1: just mathematical masturbation or you're actually doing something useful? Right?
Speaker 1: So sometimes people argue like, Okay, string theories nice, but
Speaker 1: it's not physics, it's math because it can't be tested.
Speaker 1: But that's but then that's what they need to do.
Speaker 1: They need to build up their math to sort of
Speaker 1: our scale in our world. But you're saying that's really difficult. Absolutely,
Speaker 1: it's difficult because they've got a long ways to go.
Speaker 1: They have to go from ten to the minus thirty
Speaker 1: five up to ten to the minus twenty. It's a
Speaker 1: tall mountain to climb. And they've been working on it
Speaker 1: for twenty years. And you know, like with any theory
Speaker 1: that had um fanfare and and excitement around it twenty
Speaker 1: years ago, Um, they're gonna be people who say, oh,
Speaker 1: you failed if you haven't succeeded yet, right, and so
Speaker 1: people who just sort of impatient. Are we ever going
Speaker 1: to get there? Is string theory ever going to provide
Speaker 1: something we can actually test or these guys just gonna
Speaker 1: be twiddling around on chalkboards for the next two years.
Speaker 1: But I think the problem is maybe it seems kind
Speaker 1: of random that you would think that the universe is
Speaker 1: made out of little strings, and that you would just
Speaker 1: come up with this concept out of the blue and say, hey,
Speaker 1: let's dedicate twenty thirty years of a lot of people's
Speaker 1: time to investigating this idea. You know what, it was
Speaker 1: totally random. They just opened the dictionary and picked a
Speaker 1: random or and said, let's make it into this theory
Speaker 1: out of ice cream. No, as I said before, it's
Speaker 1: a bit random, but it works. You know, mathematically, hangs together,
Speaker 1: and a lot of theories don't. You can't build a
Speaker 1: theory of the universe out of ice cream or out
Speaker 1: of puppies triangles. You couldn't make it work. Oh man,
Speaker 1: we never thought that. I that's what I mean. Have
Speaker 1: you thought about all the possible shapes stick figures. I'll
Speaker 1: be right back. Hold on, I'm gonna try and invent
Speaker 1: trying the theory right now. I'll get back to you.
Speaker 1: Stigure theory. Why not the x K C D theory
Speaker 1: of the universe? How could we c string theory? Well,
Speaker 1: one thing is you could build a super duper collider
Speaker 1: the size of the solar system and and see things.
Speaker 1: That's small, but that's the gazillion dollar solution. The other
Speaker 1: things you could try to be really clever and find
Speaker 1: some unique prediction of string theory that we could see
Speaker 1: in our experiments. Something which would only be true if
Speaker 1: strings were happening at the lowest level, right, Because in
Speaker 1: physics we don't always need to see things directly in
Speaker 1: order to prove that they exist or believe that they exist.
Speaker 1: You can kind of infer information or Yeah, a lot
Speaker 1: of our stuff is a lot of indirect information pointing
Speaker 1: in the same place. Right, Like, when you solve a murder,
Speaker 1: you don't need to see the murder on video to
Speaker 1: prove that somebody did it. You know, you have evidence
Speaker 1: from blood spatter and from DNA and from you know,
Speaker 1: other circumstantial evidence builds a solid case. It was Mr
Speaker 1: Green with the string in the dining room solved. That's right,
Speaker 1: We we have solved the mystery. Today on the podcast,
Speaker 1: all Right, what do you think the future holds for
Speaker 1: a string theory? Do you think it's it's promising or
Speaker 1: are people starting to lose faith? I think it's gonna
Speaker 1: oscillate back and forth. I think people will lose faith
Speaker 1: for a while. It's gonna vibe rate exactly, it's gonna
Speaker 1: wiggle and jiggle, it's gonna lose. You know, it's popular
Speaker 1: right now and for a while. Everybody who's aplanning grad
Speaker 1: school and physics wanted to do string theory because they
Speaker 1: heard about Brian Green's book and they heard about a
Speaker 1: big bank theory and it was popular. And then there's
Speaker 1: a bit of a backlash now, so fewer people are
Speaker 1: getting excited about string theory, fewer physics departments are hiring
Speaker 1: strength theorists. But it's a promising candidate, and we don't
Speaker 1: have that many promising candidates for the theory of everything.
Speaker 1: So it'll stick around and people will come up with
Speaker 1: great ideas and then everybody get excited again, like, oh
Speaker 1: my gosh, look this guy came up with a cool
Speaker 1: way to make stringth theory. Do this new thing. So
Speaker 1: we will go back and forth. Um, I don't know
Speaker 1: if we'll every be able to test it as a
Speaker 1: theory that we will require a real moment of insight
Speaker 1: to how to find some unique property of string theory
Speaker 1: that we can see. Well, I personally hope you guys
Speaker 1: figure it out and you know, stop stringing us along.
Speaker 1: You don't like that we're just in our offices, you know,
Speaker 1: drawing things on the chalkboard, going that's right. I thought
Speaker 1: if anybody a cartoonists would appreciate, you know, enjoying the
Speaker 1: beauty of diagrams and uh, you know, doodles and stuff
Speaker 1: like that, because that's in the end what we're doing.
Speaker 1: We're like trying to do the universe into into understanding.
Speaker 1: We'll remember, I'm a musician, not a cartoonist. Oh I
Speaker 1: forgot that. Yes, um, maybe you could sing something, go ahead, Yeah,
Speaker 1: I think us sing us to your theory of the
Speaker 1: universe materia. I'm on the edge of my scene. You'll
Speaker 1: be running away from your seat if you hear me singing.
Speaker 1: But alright, cool, that's a really great overview of the
Speaker 1: string theory, right, That's that's part of this quest to
Speaker 1: kind of find out what the universe is actually made
Speaker 1: of at the deepest level. Yeah. Absolutely, And so thanks
Speaker 1: everybody listening, and I hope that we've explained to you
Speaker 1: finally what is string theory? Keep plugging way. If you
Speaker 1: still have a question after listening to all these explanations,
Speaker 1: please drop us a line. We'd love to hear from you.
Speaker 1: You can find us at Facebook, Twitter, and Instagram at
Speaker 1: Daniel and Jorge that's one word, or email us at
Speaker 1: Feedback at Daniel and Jorge dot com.