Speaker 1: Hey, Daniel, I've noticed that people just add quantum the
Speaker 1: word quantum to things to make them sound cool. Oh man,
Speaker 1: I hate when they do that. Yeah, like quantum combs,
Speaker 1: quantum um cereal. I mean it''s like they put it
Speaker 1: on everything just to make it sound awesome. Yep. I
Speaker 1: was seeing quantum dog food recently, and I'm pretty sure
Speaker 1: that's not a real fact. Your dog both loves it
Speaker 1: and hates it at the same time. But does that
Speaker 1: mean to just all of quantum mechanics is like a scam,
Speaker 1: not all of it, Like, there really is some physics
Speaker 1: in quantum mechanics, but I'd say most things that are
Speaker 1: called quantum are probably bologny. Hi am Jorge. I'm a
Speaker 1: cartoonists and the creator of PhD Comics. Hi I'm Daniel.
Speaker 1: I'm a quantum physicist and that is not bologny. Oh well,
Speaker 1: it just happens. I'm a cartoon bologny cartoonists. So all
Speaker 1: brings it together and welcome to our podcast, Daniel and
Speaker 1: Jorge Explain the Universe, a production of I Heart Radio
Speaker 1: in which we explore everything that's crazy and amazing about
Speaker 1: the universe, from classical physics to quantum mechanics and explain
Speaker 1: it to you in a way that you can explain
Speaker 1: to your friends and sound super smart. Yeah, in ways
Speaker 1: that we do explain it and don't explain it at
Speaker 1: the same time. We're sort of like a quantum podcast
Speaker 1: in a way. We download individual, discretized units of explanation
Speaker 1: into your brain. We spin it up and spin it
Speaker 1: down for you guys. But quantum mechanics is one of
Speaker 1: my favorite topics because it is so hard for people
Speaker 1: to understand usually, but there are ways to look at
Speaker 1: quantum mechanics and get a new sense of the world,
Speaker 1: to reveal the reality that underlies everything. Yeah, it's your
Speaker 1: favorite because people don't understand it. It's my favorite because
Speaker 1: it's a great example of how in physics we can
Speaker 1: learn that the world is really quite different from the
Speaker 1: world we expected it to be. The world we grew
Speaker 1: up in is not the way the world works. That
Speaker 1: to really understand the universe, we have to remove our blinders,
Speaker 1: and quantum mechanics is a great example of that because
Speaker 1: it requires basically tossing out your entire intuition for how
Speaker 1: the world works and accepting something very different. Yeah, I
Speaker 1: feel like that every day that I wake up and
Speaker 1: read the news, like, what is this universe we're living in?
Speaker 1: What quantum politics is that you're talking about? It's just
Speaker 1: the quantum news will say, it's just the quantumy. It
Speaker 1: makes sense and doesn't make sense at the same time.
Speaker 1: It's about a dead cat and in a life cat
Speaker 1: at the same time. I feel like quantum mechanics is
Speaker 1: something a lot of people are fascinated by. They've heard
Speaker 1: about it, they hear people use words to explain it
Speaker 1: that don't quite make sense to them, and so people
Speaker 1: are thirsty for a real, honest to god understandable explanation
Speaker 1: for some of this bizarre quantum phenomena. Yeah, and it
Speaker 1: sort of seems, like you said, it almost seems like
Speaker 1: two different universes. You know. There's like the universe that
Speaker 1: you grew up and as a kid and feel you
Speaker 1: understand where you take a ball and you bounce it
Speaker 1: and comes back and you can throw a baseball and
Speaker 1: it lands where you think it's gonna land. And then
Speaker 1: there's there's the kind of the quantum universe you learned
Speaker 1: later on in life, where like none of those things
Speaker 1: you learned as a kid seem to apply precisely because
Speaker 1: your brain develops all these ideas for how things move
Speaker 1: based on what you've experienced. Things seem to move through
Speaker 1: the universe, it seems like they have a smooth path,
Speaker 1: and so later to grow up and learn that things
Speaker 1: don't actually move. They just have these snapshots and then
Speaker 1: those later snapshots in your brain is filling in the
Speaker 1: in between slices to make like a movie of the universe.
Speaker 1: Is quite shocking. I wonder if we had evolved to
Speaker 1: be much much smaller, if we would have sort of
Speaker 1: a quantum intuition, if we like had everyday experiences of
Speaker 1: quantum objects. You mean, like if it's taught at the
Speaker 1: preschool level, if we try to teach kids quantum physics,
Speaker 1: I don't think we should be doing short in your
Speaker 1: equation um one plus one, spin up, spin down, you know,
Speaker 1: just the basics that you need to deal with this
Speaker 1: crazy world we're living in. That's one approach, but I
Speaker 1: think that people would still struggle because they don't have
Speaker 1: any actual experience with it. I'm talking about really experiencing
Speaker 1: quantum mechanics, Like what if they were quantum effects that
Speaker 1: were macroscopic, you know, things that were the sizes of
Speaker 1: baseballs operated under quantum rules. It's pretty hard to reveal
Speaker 1: that the universe is quantum mechanical. It took us thousands
Speaker 1: of years before we figure that out. What if it
Speaker 1: wasn't so subtle, what if it was more obvious and
Speaker 1: so people actually had an intuition for this, they're like, oh, electrons, Yeah,
Speaker 1: those moves just like these other quantum basketballs or whatever
Speaker 1: that I was playing in within my kindergarten playground. Yeah. Yeah,
Speaker 1: maybe that's the next wave of physics education, is we
Speaker 1: need to develop some sort of technology that operates like
Speaker 1: quantum objects so kids can play with like quantum balls. Yeah. Well, um,
Speaker 1: it does seem like it's kind of a separate and
Speaker 1: new universe, and it feels like there's a quantum version
Speaker 1: of almost anything. Like for anything that we have in
Speaker 1: our world, there seems to be like a quantum version
Speaker 1: of it. Like you know, I know I can spin
Speaker 1: here in my chair, and there's also something called quantum spin,
Speaker 1: and you know, my battery has charged at it, but
Speaker 1: there's also something called quantum charge and so on and
Speaker 1: so on. Yeah, there's even quantum flavor. Yeah, you think
Speaker 1: in kindergarten that there's only sweet and salty and sour,
Speaker 1: but there's also quantum flavor, and we have quantum color.
Speaker 1: We had a whole podcast episodes about all these. Yeah,
Speaker 1: so you can go to quantum Kindergarten too and learn
Speaker 1: quantum sharing and quantum And in some cases these things
Speaker 1: are metaphors, like quantum flavor. These particles don't actually taste
Speaker 1: like anything, but we're trying to make an analogy. We're
Speaker 1: trying to extrapolate from something we know, which is flavor,
Speaker 1: and give you a sense for this weird new quantum thing.
Speaker 1: But in other cases it really does make sense, like
Speaker 1: quantum spin. Those particles are not spinning in the same way,
Speaker 1: but they really do have angular momentum, so spin really
Speaker 1: makes sense. So in some cases the words are you know,
Speaker 1: really a stretch. In some cases they really are applicable, right, Yeah,
Speaker 1: that was a pretty good way to you just sput
Speaker 1: it there, right, so obvious and clear. But but yeah,
Speaker 1: but sometimes you know, I wonder, sometimes I wonder if
Speaker 1: it are pushing it a little bit too much. And
Speaker 1: so today on the podcast, we have a great question
Speaker 1: from a listener that we're going to try to answer.
Speaker 1: And this is a question from Dale from Dublin. We
Speaker 1: had a very interesting question and about another strange sounding
Speaker 1: quantum thing. Here's Dale Dale from Toblin oiland here I
Speaker 1: heard about a thing called quantum phone or spacetime phone.
Speaker 1: Could you talk about that for a bit and let
Speaker 1: us know what it is? Chairs Well, I love so
Speaker 1: many things about this. First of all, I love Dale's
Speaker 1: accent awesome, and I love the Dale wrote in. This
Speaker 1: is just an email he sent me saying, hey, can
Speaker 1: you explain this? And I asked him to send us
Speaker 1: a recording so we could talk about it on air
Speaker 1: because I thought a lot of people might be interested
Speaker 1: in the answer to this question. So thank you Dale
Speaker 1: for writing in, and thank you to everybody who writes
Speaker 1: in with their questions. Right, and just as a reminder,
Speaker 1: we are on Instagram and Twitter at Daniel and Jorge
Speaker 1: and if you want uh Daniel to answer back, try
Speaker 1: Twitter or the email because Instagram will not answer your question.
Speaker 1: I don't do quantum social media. Yeah, so if you
Speaker 1: have a question, send it on into questions at Daniel
Speaker 1: and Jorge dot com or engage with us on Twitter
Speaker 1: at Daniel in Jorge. Yeah, so this is an interesting question.
Speaker 1: Quantum foam. It's sort of sounds like one of these
Speaker 1: products that you sell in late night television that will
Speaker 1: totally clean your bathroom at the molecular level. I think
Speaker 1: a lot of times in marketing, quantum is just used
Speaker 1: to describe something to make a sound more modern or technological.
Speaker 1: You know, like like quantum dog food. That really is
Speaker 1: a thing. I mean, it's your mechanical No, Google, quantum
Speaker 1: dog food. There is a product they really do sell
Speaker 1: dog Foodn't call it quantum. I think what they mean
Speaker 1: by that is new fancy, you know, savvy to the
Speaker 1: quantum mechanical world somehow new fancy. Yeah, well that's kind
Speaker 1: of what you guys do in physics as well, isn't it. Oh,
Speaker 1: this is a charge, but it's kind of new and fancy.
Speaker 1: We'll call it quantum quantum. Wait, no, but it actually
Speaker 1: is new and fancy. Sometimes we do discover stuff in physics.
Speaker 1: It's new and fancy. All the quantum mechanics is new
Speaker 1: and fancy. It really does happen. It's not just marketing.
Speaker 1: Sometimes dog food is new and fancy. Why not and
Speaker 1: coming districted little chunks? That's true? Yeah, alright, so I
Speaker 1: should order that product and I should evaluate it before
Speaker 1: I give my opinion on it. You're totally right and
Speaker 1: content doct food. Please give us a call. We are
Speaker 1: opening for sponsorship. In this podcast, I was wondering if
Speaker 1: Dale from Dublin was the only person thinking about spacetime foam,
Speaker 1: and so I walked around and I asked people what
Speaker 1: they thought about space time folm, had they heard of it?
Speaker 1: Did they know what Dale was talking about? Did they
Speaker 1: have any idea what it was? And these questions again
Speaker 1: didn't happen to e c Irvine. This happened at a
Speaker 1: local coffee shop because I was trying to get a
Speaker 1: sense for the broader public and their understanding of this topic. Yeah,
Speaker 1: so before you listen to these answers, think about it
Speaker 1: for a second. If a physicist approached you at a
Speaker 1: coffee shop, would you be able to answer the question,
Speaker 1: what is spacetime foam? Here's what people had to say,
Speaker 1: upper layer to spacetime that kind of bubbles up or something.
Speaker 1: If that makes sense, Well, I'm no idea. I have
Speaker 1: no idea spacetime phone, no spacetime phone, no spacetime phone
Speaker 1: for space. I guess, but I don't um space. I'm
Speaker 1: not all right. I feel like people were answering and
Speaker 1: they were just about to call the police on you.
Speaker 1: On these you can sort of hear that in responses.
Speaker 1: They're like, I am so regretting answering this questions. What
Speaker 1: are you talking about? I think, yeah, I mean people
Speaker 1: go to a coffee shop to wake up, and you're
Speaker 1: asking them physics questions over their cappuccimo phone. Well, you know,
Speaker 1: I specifically tried to choose people that looked like they
Speaker 1: were studying, like they had a book open and they
Speaker 1: were reading something, because I was hoping to find people
Speaker 1: who were, you know, like had their brains on or intellection,
Speaker 1: engaged in something, or maybe curious about this kind of thing.
Speaker 1: I didn't interrupt, like couples that were smooching, or if
Speaker 1: they looked like they were listening to a podcast, You're like,
Speaker 1: that person probably knows everything already, right. I try to
Speaker 1: avoid people who already have their earbuds in, because I
Speaker 1: feel like in public, earbuds mean don't talk to me. Well,
Speaker 1: this is kind of an interesting question. Quantum foam and
Speaker 1: I I had never heard of it. If you have
Speaker 1: approached me at a coffee shop, I would have just
Speaker 1: said no, please, go on, please please asked me an
Speaker 1: easier question. You would have been like, you look like
Speaker 1: this other physicist I know, and I definitely ignore him
Speaker 1: in public. So I'm not talking to you as a
Speaker 1: blanket policy. That's my decision on physicists. All right, So
Speaker 1: this is an interesting question because it's it's like you're
Speaker 1: marrying two words that are very common space time and foam,
Speaker 1: but that together really don't make any sense. Yes, And
Speaker 1: that happens so much in quantum mechanics. People say things
Speaker 1: that use words together and you understand the individual words,
Speaker 1: but you don't really know what it means when you
Speaker 1: put it together. So we'll get into what spacetime foam
Speaker 1: is and what we know about it and how we
Speaker 1: might be able to find it in in this frothy
Speaker 1: little universe we live in. But first let's take a
Speaker 1: quick break, all right, Dannel, we're talking about spacetime foam,
Speaker 1: and it's not a weird product that you sell on
Speaker 1: late night television. It's an actual physical theory in science,
Speaker 1: and so let's get into that a little bit. And
Speaker 1: I guess let's start with the first two words to
Speaker 1: set us up for the foamy part um. So let's
Speaker 1: talk a little bit about spacetime, because in this case,
Speaker 1: I think Dale from Dublin used the word as one word,
Speaker 1: like spacetime, not space common time. He called it spacetime.
Speaker 1: So let's maybe refresh for our listeners what it means
Speaker 1: to say spacetime. Yeah, it's like you take two words
Speaker 1: you put them together. They mean something special, like green
Speaker 1: and house. Greenhouse is not just a greenhouse, right, has
Speaker 1: its own meaning. So in the same way space time
Speaker 1: is sort of a special word in physics, and of
Speaker 1: course you know it's spaces. Space is just the three
Speaker 1: dimensions of movement. You know, you have X, y, and Z.
Speaker 1: And we have a whole other episode about like what
Speaker 1: makes up space? Is it a thing because it can
Speaker 1: wiggle and dance and jiggle and expand and all this stuff.
Speaker 1: But for our purposes today, let's just think about it
Speaker 1: as sort of as the directions you can move in X, Y,
Speaker 1: and Z. So that's what space means, like the space
Speaker 1: we're in, like where we move around in. Yeah, precisely,
Speaker 1: nothing special there. And time is just time, right, time
Speaker 1: flows forwards, and you can think of time in analogy
Speaker 1: to space. You can think of us as moving through
Speaker 1: time the way you can move through space. And we
Speaker 1: have a whole podcast episode digging into how time is
Speaker 1: connected to space and how time is different from space.
Speaker 1: But Einstein is the guy who put these two things together.
Speaker 1: He's the first one to construct this idea of space
Speaker 1: time by taking three dimensions of space that you can
Speaker 1: move in and adding the time dimension to it is
Speaker 1: sort of a fourth dimension. So together space time is
Speaker 1: this four dimensional idea X y Z and then time. Right,
Speaker 1: I feel like you just said something profound though you
Speaker 1: just said time is time. That man, time is so fascinating.
Speaker 1: I could talk endlessly about time. We could spend all
Speaker 1: of our time talking about time. But maybe it's not
Speaker 1: time to do that. That one phrases made me think
Speaker 1: about my whole life and where I'm going with it.
Speaker 1: And well, can I sell you my new product. It's
Speaker 1: called quantum time the There you go, alright, quantum quantum
Speaker 1: watch to keep track of the inevitability of time. It's
Speaker 1: new and fancy and has to be charged every fifteen minutes.
Speaker 1: There you go, alright. So spacetime is this idea that um,
Speaker 1: space and time are not separate, like maybe if you
Speaker 1: think about them altogether in one package, one four dimensional bundle.
Speaker 1: Then it's more appropriate somehow like uh like the related
Speaker 1: like one of them affects the other, so therefore you
Speaker 1: should keep track of them all at the same time precisely.
Speaker 1: And it was Einstein's theory of special relativity that showed
Speaker 1: us exactly how space and time are affected by each other. Specifically,
Speaker 1: how time flows depends on where you are and how
Speaker 1: fast you are going relative to something else, and so
Speaker 1: in order to understand time, you can't just have time
Speaker 1: by itself. Time is not universal. Time is local. Time
Speaker 1: depends on where you are in space, and so it
Speaker 1: makes much more sense to combine these two things together.
Speaker 1: It's like having the weather, right. The weather is not
Speaker 1: the same everywhere, so you want to talk about the
Speaker 1: weather where you are in Buffalo, or in New Delhi
Speaker 1: or in Barcelona, and so you pair the weather with
Speaker 1: the location because that makes more sense. It's called the
Speaker 1: space time weather continuum, which you hear listen to my
Speaker 1: new quantum weather reports. It's a new Toppler quantum three
Speaker 1: thousand that probably is a real thing. I mean, you're joking,
Speaker 1: but there's probably some will station out there with quantum weather.
Speaker 1: Dobbler some local weatherman in the middle of Barcelona. And
Speaker 1: Geinstein was not crazy, right, Like, he didn't just make
Speaker 1: this up and it didn't work. It actually works, Like
Speaker 1: bundling space and time together does tell you something about
Speaker 1: the universe, and it's there's been theories and experiments done
Speaker 1: to prove that this is all for real. Oh, yes,
Speaker 1: Einstein was right about this. That doesn't mean Einstein wasn't crazy.
Speaker 1: I mean, you dig into that guy's personal life. He
Speaker 1: was more than a little bit across. What do you mean.
Speaker 1: He was also right about spacetime, all right, So that spacetime.
Speaker 1: And now the question from Dale was what is spacetime foam?
Speaker 1: And I have to say, I've never heard of this before.
Speaker 1: Is this a new thing? Is this something that's only
Speaker 1: been around for a couple of years, or is this
Speaker 1: like a fringe theory or French theory? I don't know
Speaker 1: either one. What is what is going on with spacetime phoam? Well,
Speaker 1: I can't endorse your casual slander of entire culture there,
Speaker 1: but it is a bit of a fringe in theory.
Speaker 1: It's one of these things. It's like it's an idea
Speaker 1: that took hold in some people's minds, but then not
Speaker 1: a lot of progress was made, so so HA just
Speaker 1: been hanging out there, bubbling up in people's brains without
Speaker 1: really turning into anything concrete. So it's been around for
Speaker 1: a while, but it's not really part of the mainstream physics.
Speaker 1: It's just been foaming up in people's research dockets. And
Speaker 1: so I know that you keep abreast of all the
Speaker 1: latest topics in physics and you read all the physics journals,
Speaker 1: and that's probably why you haven't heard about this recently. Right, Well,
Speaker 1: at first I thought it was maybe an acronym, like
Speaker 1: maybe fo a M stands for something. It's the first
Speaker 1: of a multiverse, which is a new theory by Jorge
Speaker 1: Cham about how we're the most awesome of all the multiverses.
Speaker 1: And somehow Dale from Dublin knew about your theory before
Speaker 1: you even thought about it and thought to ask in advance. Wow,
Speaker 1: good job, Dale. Yeah, well, in other multiverses he didn't,
Speaker 1: but this one, because it's the best he did, all right,
Speaker 1: So let's let's talk about this. So there is something
Speaker 1: called spacetime foam that physicists think might be real and
Speaker 1: might actually kind of describe what the universe is like,
Speaker 1: so take us through it, Daniel, what does it mean
Speaker 1: to put the word spacetime and foam together? The idea
Speaker 1: here is to try to resolve the conflict between our
Speaker 1: two great theories of physics. We talked about space time
Speaker 1: in terms of relativity, and that all makes sense. And
Speaker 1: relativity has been tested out the wazoo and up the
Speaker 1: wazoo and in the wazoo in every way around the wazoo.
Speaker 1: Because is that it's a great theory. Is that another
Speaker 1: physics experiment acronym the wazoo, the wazoo, I'm not sure
Speaker 1: what it means collider in Italy apparently, but special relativity
Speaker 1: has been extensively tested, and so has general relativity. But
Speaker 1: we don't know if it really holds universally. That we
Speaker 1: have suspicions that it probably doesn't work on really really
Speaker 1: tiny distances. So general relativity said is that space is
Speaker 1: sort of smooth, that you can chop it up into
Speaker 1: tinier and tinier bits and you'll never sort of run
Speaker 1: out of ways to cut it in half. That like
Speaker 1: in Zeno's paradox, you could take smaller and smaller steps forever.
Speaker 1: That's what general relativity says. It predicts it, or it
Speaker 1: assumes it. It assumes that it it uses that as
Speaker 1: its essential description of what space is. That you could
Speaker 1: have a particle or an object located at any point.
Speaker 1: You know, if you have an infinite number of locations
Speaker 1: between me and you, that a particle could be at
Speaker 1: any of those locations. Oh, I see. It's kind of
Speaker 1: like Newtonian physics, right almost in a way, like it
Speaker 1: assumes that space is smooth, and it doesn't assume anything
Speaker 1: that's that anything is quantized. That's right, And you look
Speaker 1: at the universe around you, and the universe seems smooth, right,
Speaker 1: It seems like you could sit anywhere. It seems like
Speaker 1: if you took a ruler, you could cut it in
Speaker 1: an infinite number of ways. Whatever that there's an infinite
Speaker 1: number of ways. But just like the screen on your
Speaker 1: iPhone looks really crisp and smooth, but if you zoom in,
Speaker 1: you discover that there are pixels there. And so general
Speaker 1: relativity tells us that the universe is smooth. That's space
Speaker 1: is infinitely sliceable. But that's in conflict with quantum mechanics.
Speaker 1: Quantum mechanics says that you can't have infinitely sliceable space. Yeah,
Speaker 1: that at the fundamental level, it's pixelated, kind of like
Speaker 1: my iPhone screen. Although my iPhone screen these days looks
Speaker 1: kind of blurry because as I've said before, I need
Speaker 1: reading glasses. Now I'm not sure that's a problem with
Speaker 1: your iPhone screen, but well it's a it's a problem
Speaker 1: for my new quantum reading glasses. Yeah. And so quantum
Speaker 1: mechanics has this impact on lots of things that we measure.
Speaker 1: Things that at large scales seem smooth turn out to
Speaker 1: be discretized, turned out to be sliced up into chunks.
Speaker 1: Like a flashlight beam is not a smooth, continuous beam
Speaker 1: of light. It's a stream of tiny little packets called photons.
Speaker 1: The same way your bowl of ice cream is not
Speaker 1: infinitely chopped herble into smaller and smaller spoonful. There are
Speaker 1: atoms in there. It's made out of these tiny little
Speaker 1: lego pieces. So the same concept can be applied to
Speaker 1: lots of things, and quantum mechanics says that probably it
Speaker 1: also applies to space. So we have this conflict between
Speaker 1: these two great theories of physics, relativity and quantum mechanics,
Speaker 1: and the conflict lies in a place that's really hard
Speaker 1: to spot where things are super duper small, so meaning
Speaker 1: that general relativity doesn't know that there's something called quantum
Speaker 1: physics and quantum mechanics. Quantum physics sort of we don't.
Speaker 1: Do we know that quantum mechanics takes into account general
Speaker 1: relativity or is there such a thing as bending a
Speaker 1: space and quantum mechanics. So that's a great question. People
Speaker 1: have tried to say, let's take Einstein's theory of general
Speaker 1: relativity and let's make a quantum version of it. Can
Speaker 1: we make a version of general relativity where space is
Speaker 1: pixelated or we know quantum mechanics comes into account, and
Speaker 1: currently we have no great functioning theory like these. Reason um,
Speaker 1: you can make a theory of general relativity that is quantized,
Speaker 1: but it doesn't work when space is really intense, like
Speaker 1: inside a black hole. When the gravity gets really really strong,
Speaker 1: then the theory breaks down and predicts things that don't
Speaker 1: make sense. It gives you like infinities and all sorts
Speaker 1: of crazy numbers. So we don't currently have a working
Speaker 1: theory of what's called quantum gravity that tries to marry
Speaker 1: all the best things from general relativity and quantum mechanics.
Speaker 1: So does that mean that quantum mechanics operates kind of
Speaker 1: in a Newtonian or like perfect kind of pre Einstein universe.
Speaker 1: Quantum mechanics operates often in if what we call a
Speaker 1: flat space, you know, space that's not bent by mass.
Speaker 1: You can do quantum mechanics in curved space, where if
Speaker 1: you're like near the Sun or near a black hole
Speaker 1: and space is curved, you can do that quantum mechanics.
Speaker 1: But if you try to do it when space is
Speaker 1: too curved, when the gravity gets really really strong, then
Speaker 1: it just doesn't work. We just don't even have a theory.
Speaker 1: We can't like even come up with a theory that
Speaker 1: makes sensible predictions, not to mention check those predictions against
Speaker 1: actual experiments. All right, So it sounds like general relativity
Speaker 1: is good for kind of big distances and tells us
Speaker 1: how the universe works at large scales, and quantum mechanics
Speaker 1: tells us how it works in really really tiny scales.
Speaker 1: But there are situations where the two theories just don't.
Speaker 1: Neither of them work. Yeah, and what we need to
Speaker 1: do is get inside a black hole and see what
Speaker 1: happens when you have both small distances. So quantum mechanics
Speaker 1: is relevant and really intends gravity, so general relativity is relevant. Unfortunately,
Speaker 1: all the people we've sent into black holes have not
Speaker 1: been coming. Yeah, I was gonna say that you're using
Speaker 1: the word we they're pretty broadly. There any volunteers out
Speaker 1: there who wants to be the first person to die
Speaker 1: at a black hole. And this is where the idea
Speaker 1: of space time foam comes from. It comes from an
Speaker 1: attempt to try to reconcile these two theories. I see.
Speaker 1: It's a it's another one of these unifying theories, like
Speaker 1: theories of everything. Precisely. There's one theory that says maybe
Speaker 1: the universe is made out of tiny little loops. That's
Speaker 1: called loop quantum gravity. Another one says maybe everything is
Speaker 1: just a tiny vibrating string at string theory. There's even
Speaker 1: one called spin foam, where everything is like this weird
Speaker 1: spinning kind of foam. But spacetime foam is a particular
Speaker 1: theory that tries to unify quantum mechanics and general relativity,
Speaker 1: and it imagines space is being made of these tiny
Speaker 1: little pixels, but these pixels would be quantum mechanical and
Speaker 1: so like bubbles and a frothing foam they might like
Speaker 1: pop in and out of existence. All right, let's get
Speaker 1: people in the loop of this and get a little
Speaker 1: bit more into what quantum foam or spacelime foam is
Speaker 1: and how we know about it and what we might
Speaker 1: discover if we poke around in the universe. But first,
Speaker 1: let's take another quick break. Yeah, all right, Daniel. So
Speaker 1: quantum foam is kind of like quantum dog food, and
Speaker 1: that you know, you're trying to make something that your
Speaker 1: dog will both eat and enjoy at the same time.
Speaker 1: We're trying to make something that explains both general relativity
Speaker 1: and quantum mechanics all and that your dog will like,
Speaker 1: I guess, also um at the same time. And so
Speaker 1: and that's hard because, as you said, they're sort of
Speaker 1: based on two very different views of the universe, that's right.
Speaker 1: And you know, for relativity to work, what we need
Speaker 1: is a new imagining of it. We need to start
Speaker 1: from a different conception of what space is. Einstein assumed
Speaker 1: that space was smooth and continuous, and he built his
Speaker 1: theory upon that assumption. So we need to start from
Speaker 1: a different assumption and say, actually, spaces made of these
Speaker 1: tiny grains or these little bubbles and under stand the
Speaker 1: nature of those and then build a theory on top
Speaker 1: of that. And I don't know this is true. It's
Speaker 1: not clear that spacetime boom is a real description of space.
Speaker 1: You know. It might be the pixels are a better description,
Speaker 1: or loops or little strings, or we really just don't know,
Speaker 1: but we need a new idea. And so theorists are
Speaker 1: just sort of being creative and smoking banana peals and saying, well,
Speaker 1: maybe it's more like this, and you know, you look
Speaker 1: around the macroscopic universe to get inspiration, you know, and
Speaker 1: maybe some physicist was smoking a banan appeal and looking
Speaker 1: at soap bubbles and thinking, huh, maybe space is just
Speaker 1: like that. Well it's it's interesting because I feel like,
Speaker 1: you know, there's these two theories and it's not like
Speaker 1: you're saying like, oh, maybe quantum mechanics is wrong, and
Speaker 1: really we just need to extend general relativity, or you're
Speaker 1: not saying, oh general relativity is wrong, we just need
Speaker 1: to extend quantum mechanics. I feel like you're saying that
Speaker 1: we we need to throw both of these into the
Speaker 1: garbage and kind of come up with one theory, start over,
Speaker 1: re imagine the universe and come up with one theory
Speaker 1: that you know, it sort of looks like one and
Speaker 1: looks at the other, but actually kind of works continuously
Speaker 1: across the whole universe. Yeah, well, we don't know what
Speaker 1: the necessary process will be. It might be that we
Speaker 1: can take what we have from general relativity and from
Speaker 1: quantum mechanics and marry them um. Or it might be that, yeah,
Speaker 1: we have to toss it out and start all over again.
Speaker 1: The process of science is iterative, right. It's like a
Speaker 1: writer writing a draft of a screenplay or something. You
Speaker 1: just keep trying to make it better and better until
Speaker 1: it fits, and then at some point you realize, you
Speaker 1: know what, this is hot mess of garbage, and you've
Speaker 1: got to toss it out and start all over again.
Speaker 1: So we don't know. We don't know if you know,
Speaker 1: we're one more draft away from something we can publish,
Speaker 1: or if you've got to toss it all out and
Speaker 1: start on the next book, right, Or maybe the studio
Speaker 1: head goes, well, it's too late, let's just make this
Speaker 1: bad movie and can you make it funnier? And we
Speaker 1: live in that universe that should never have been made
Speaker 1: where the plant is It don't make any sense? And
Speaker 1: the acting is stiffid best. That's even better than do
Speaker 1: we live in a simulation? Is? Do we live in
Speaker 1: a poorly written sim simulation? Like that? I got notes
Speaker 1: for you simulation authors. Okay, here's how you should have
Speaker 1: done the simulation. Here's what rotten Tomato says about your
Speaker 1: universe business ratings on on universe simulations. I like it.
Speaker 1: There you go. Quantum Rotten Tomatoes is the name of
Speaker 1: my new website. Check it out. Alright, So step us through.
Speaker 1: What is quantum foam? Then? Is it? What does it
Speaker 1: poe mean? Why is it phone? It have bubbles in it?
Speaker 1: Is it like a froth? Why is it called quantum phone? Yeah?
Speaker 1: The idea is that quantum mechanical things fluctuate. They come
Speaker 1: in and out of existence. If you zoom into particles
Speaker 1: at the smallest scale, you can't follow them along the
Speaker 1: way you would follow a baseball. They sort of pop
Speaker 1: into existence and pop out of existence. They turn into
Speaker 1: other particles. It's like a constant mess, right, and so
Speaker 1: lots of things are happening like it's bubbling at the surface,
Speaker 1: kind of like foam. Those are the things in space
Speaker 1: and times. This is saying that space, time itself is
Speaker 1: like a phone, right, And so if space itself is quantized,
Speaker 1: it's made out of these pixels, and these pixels are
Speaker 1: quantum mechanical, then it's possible that the pixels themselves are
Speaker 1: sort of bubbling in and out of existence. It's one
Speaker 1: step to go from space is smooth to space is
Speaker 1: discrete r it's made of pixels. It's another to say,
Speaker 1: maybe those pixels themselves are not like permanent, they're like temporary,
Speaker 1: you know, they're ephemeral. They're coming in and out of
Speaker 1: existence because in the end, a lot of quantum mechanical
Speaker 1: things are Space itself is coming into and out of existence,
Speaker 1: like yeah, like this bit of space run in front
Speaker 1: of my eyes here precisely the you know, the object
Speaker 1: in front of you, for example, whatever it is, it's
Speaker 1: in front of you right now. It's a banana, or
Speaker 1: it's an apple or whatever, that's made of quantum mechanical particles.
Speaker 1: Now it seems solid, it seems like it's really there.
Speaker 1: But if you zoomed in on the little particles, the
Speaker 1: particles that make it up are popping in and out
Speaker 1: of existence. They're turning into energy, they're turning back the
Speaker 1: particles that changing into other particles and then coming back
Speaker 1: you don't even notice, right, So that phone or whatever
Speaker 1: in front of you is a frothing mess, but you
Speaker 1: just don't notice it frothing because the frothing is so tiny.
Speaker 1: So if it's hard for you to imagine, like that
Speaker 1: space itself could also be frothing. Remember everything around you
Speaker 1: is kind of frothing. Oh wait, so this would be
Speaker 1: like under the quantum particles. Like you could have a
Speaker 1: quantum particle and it's really tiny, but the space it
Speaker 1: is sitting on could be bubbling underneath it. Is that
Speaker 1: what you're saying precisely, And remember that in modern quantum mechanics,
Speaker 1: we don't even really think of particles as like the
Speaker 1: basic element of stuff in the universe. Particles are just
Speaker 1: excited states of quantum fields. And quantum fields they had
Speaker 1: a whole episode on, are a property of space itself.
Speaker 1: So you can't really separate the matter and the space
Speaker 1: because matter is just an excited state of quantum fields,
Speaker 1: which are a part of space, but is the spacetime
Speaker 1: foam on the same scale as the particles like um
Speaker 1: you know what mean? Like what if there's a particle
Speaker 1: that just happens to be sitting on a spacetime bubble
Speaker 1: and that bubble pops. Does that particle just disappear or
Speaker 1: is it like riding on top of a whole bunch
Speaker 1: of little spacetime bubbles. Yeah, I think you have to
Speaker 1: think of particles as part of space, because particles are
Speaker 1: again excited states of these fields, and the fields themselves
Speaker 1: are part of space. And so I thinks it takes
Speaker 1: a whole new way of thinking about like the nature
Speaker 1: of the universe at the smallest scale. It's not like
Speaker 1: particles are sort of filling in slots in space. They're
Speaker 1: like excited space. Oh and you're saying that this space
Speaker 1: is actually more like foam, meaning that it's just a
Speaker 1: whole bunch of little pockets of it kind of pressed together,
Speaker 1: and each one of these pockets is a quantum of
Speaker 1: space time. That's right. And we don't know the size
Speaker 1: of these bubbles. If these bubbles exist, and we don't
Speaker 1: know that they do, the question is how big would
Speaker 1: they be? And we suspect if they do exist, they'd
Speaker 1: be super duper duper duper tiny. But you have the
Speaker 1: idea is that you know you have a localization of
Speaker 1: energy that energy is an excited state of all the
Speaker 1: quantum fields in that space, and that localization of energy
Speaker 1: you could extend across multiple bubbles of quantum space, perhaps
Speaker 1: for example, like a photon, and that you know, it
Speaker 1: could be made of these little frothing bubbles. They're smaller
Speaker 1: than that packet of energy. And so what am I
Speaker 1: doing when I'm moving through space? Am I moving from
Speaker 1: bubble to bubble? Or do I take like each one
Speaker 1: of my particles might be in this bobble, bubble or
Speaker 1: that bubble. Well, you are those bubbles. You're not in
Speaker 1: those bubbles. You are those bubbles and the spacetime foam.
Speaker 1: You are the spacetime boam, and so am I. We
Speaker 1: are all one with the spacetime foam. Remember, you are
Speaker 1: just an excited state of the space that you are occupying.
Speaker 1: And when you move that information, then that energy then moves,
Speaker 1: you know, it excites another part of the quantum space.
Speaker 1: It's like you are the wave on the string. Right.
Speaker 1: If I'm holding a string and I wiggle it, you
Speaker 1: can say, like where does that wiggle? It moves along
Speaker 1: the string the same way you are wiggling the quantum
Speaker 1: fields where you are now and then when you travel
Speaker 1: somewhere for Thanksgiving, you're gonna wiggle those quantum fields. So
Speaker 1: don't think about it as you are particles in space somewhere,
Speaker 1: but you are excited wiggling of space. Oh, I see,
Speaker 1: I'm just an excitation from one bubble to the next bubble, precisely.
Speaker 1: And the idea of spacetime foam is that maybe space
Speaker 1: is discretized and those little discrete blobs are popping in
Speaker 1: and out of existence. They're like not long lasting, They're
Speaker 1: not eternal or permanent. They're sort of frothing, oh, coming
Speaker 1: in and out. But what if I get stuck in
Speaker 1: one that pops, I wouldn't recommend that. Does that mean
Speaker 1: I'm no longer in existence? Then you don't have to
Speaker 1: buy quantum pet food for your quantum dog because the
Speaker 1: quantum out of existence. You know, these things are at
Speaker 1: a very very small scale. So unless you're a particle
Speaker 1: on the size of quantum foam, you don't have to
Speaker 1: worry about it. But also energy is conserved. So if
Speaker 1: space is frothing somewhere and energetic, and there's an excitation
Speaker 1: enough space here, that energy is going to go somewhere,
Speaker 1: maybe into the next bubble with the next bubble, So
Speaker 1: the bubble itself might pop out of existence, but the
Speaker 1: energy that is represented by that excitation is not going
Speaker 1: to go away. Oh, it's just gonna move on to
Speaker 1: another bubble. Yeah, that's what you do. When you move
Speaker 1: from place to place. You are exciting those fields, and
Speaker 1: now you're exciting these fields over here, all right. And
Speaker 1: so there's a theory that says that the universe at
Speaker 1: the very core level is like a foam, But that's
Speaker 1: just one competing theory about what it looks like down there.
Speaker 1: How are we going to find out which one it is?
Speaker 1: How do we know if the universe is foaming or
Speaker 1: if it's well, we need lots of money to build
Speaker 1: a huge particle collecit That's my answer to everything, right right, Money,
Speaker 1: It just solves everything for you, doesn't it any It
Speaker 1: sort of does you know? If you want to answer
Speaker 1: questions about high energy or heavy particles or tiny distances,
Speaker 1: which you need is a microscope to look at the
Speaker 1: really really small And the only thing that prevents us
Speaker 1: from looking at really really small spaces is having enough
Speaker 1: money to build a big enough microscope. We know how
Speaker 1: to do. It is just really expensive, so we could
Speaker 1: probe these distances. We think the distances involved or something
Speaker 1: like ten to the minus thirty five meters, which is
Speaker 1: ridunculously tiny. Like if you had a microscope with not
Speaker 1: just like a ten x hundred eggs, but like tend
Speaker 1: to the thirty five x, we might be able to
Speaker 1: see these phone bubbles and time. Yeah, we had a
Speaker 1: whole episode about how you see tiny things and microscopes
Speaker 1: and electron microscopes and particle colliders, so people should dig
Speaker 1: into that if they want more information. But basically we
Speaker 1: can see down to tend to the minus twenty right now,
Speaker 1: which is pretty impressive. We think these bubbles are tend
Speaker 1: to the minus thirty five, so fifteen orders of magnitude
Speaker 1: is is actually still a lot. You know, there's a
Speaker 1: we're far away from being able to see these pixels.
Speaker 1: So that's one way is to build a really big collider.
Speaker 1: Another is to try to use like really long distances
Speaker 1: in space ah to use as base itself like a microscope.
Speaker 1: The idea is if space is bubbling and frothing, then
Speaker 1: you know it's sort of constantly changing. That means that
Speaker 1: like the distance that light has to travel from point
Speaker 1: A to point B is not necessarily fixed. So they
Speaker 1: do these crazy experiments where they look at something really
Speaker 1: really far away and they try to see it in
Speaker 1: two different ways. They try to understand, like, you know,
Speaker 1: let's look at two photons that left that really bright
Speaker 1: source of light maybe a quasar, at the same moment,
Speaker 1: and see if they arrived here on Earth at the
Speaker 1: same time. If there's a difference, then maybe that's because
Speaker 1: there was more quantum foam bubbling up for one photon
Speaker 1: then for the other. Oh, I see, because it's foamy.
Speaker 1: That means the path you take through this foam is
Speaker 1: sort of random. And so like one photon could have
Speaker 1: hit a really foamy patch I guess, and and gone
Speaker 1: through a little bit of extra space more than the
Speaker 1: other particle who just happened to go through a part
Speaker 1: of space it wasn't as foamy, and so that would
Speaker 1: tell you like, oh, space is not consistent, it's kind
Speaker 1: of frothy. That's the idea. I have to say that.
Speaker 1: I'm skeptical because you know, on long distance scales, so
Speaker 1: you would think that these things would average out, like
Speaker 1: you're going for a billion years, then the number of
Speaker 1: random tosses of a coin are gonna be pretty close
Speaker 1: to So two photons flying through incredible distances in the universe,
Speaker 1: you know we're going to have pretty even odds to
Speaker 1: go roughly the same distance. Anyway, they look at these photons,
Speaker 1: they don't see anything, no surprise, and so they haven't
Speaker 1: discovered quantum foam. All right, Well, do you think we'll
Speaker 1: ever discover whether the universe is made out of quantum
Speaker 1: foam or not? I think we will. I think it
Speaker 1: will require some really clever mathematics to come up with
Speaker 1: like how these theories might actually work. Because remember, we
Speaker 1: don't have a functioning theory. We don't have a theory
Speaker 1: we can actually go test the theory. If we ask
Speaker 1: you questions, it gives us gibberish. And so we need
Speaker 1: to come up with a good theory, and then we
Speaker 1: need to be really clever about how to test it.
Speaker 1: And I think maybe some time far in the future,
Speaker 1: when we can get closer to black holes, will be
Speaker 1: able to test some of these theories in environments with
Speaker 1: really intense gravity. But it's pretty far off in the future.
Speaker 1: So we need clever ideas and we need awesome new experiments, right,
Speaker 1: I guess all of that is just to say, San Daniel,
Speaker 1: more money is the entire takeaway. Who needs sponsorship from
Speaker 1: quantum dog food when you can just have a whole
Speaker 1: podcast to ask people for money. That's right. Email me
Speaker 1: your quantum dollars to contributions at Daniel and Jorge dot com.
Speaker 1: Oh yeah, that does feel like my bank account. It's
Speaker 1: both there and not there. It's constantly fluctuated. Yeah, it's
Speaker 1: poemy have phoney money, not phony money, phony money. All right, Well,
Speaker 1: thank you Dale from Doubling. We hope that answered your
Speaker 1: question about what quantum foam or spacetime foam is, and
Speaker 1: I guess the answer is stay tuned. Yeah, it's a
Speaker 1: really fun idea. It's fun to speculate about what the
Speaker 1: universe might be like at the smallest scales. It's fun
Speaker 1: to take ideas from our everyday world and see if
Speaker 1: they apply at the quantum scale. But today we don't
Speaker 1: really know if quantum bom is a thing or just
Speaker 1: an idea bubbling up in the mind of physicists. So
Speaker 1: keep on looking and keep us sending us your questions.
Speaker 1: We're happy to answer them. All right. We hope you enjoyed. Dad.
Speaker 1: Thank you for joining us see you next time. Before
Speaker 1: you 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 on 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. Thanks for listening
Speaker 1: and remember that Daniel and Jorge Explain the Universe is
Speaker 1: a production of I Heart Radio. For more podcast from
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