Speaker 1: Hey, Daniel, do you enjoy doing housework?
Speaker 2: There's something satisfying about it compared to the abstraction of research.
Speaker 2: You know, you start doing dishes and then the dishes
Speaker 2: are done.
Speaker 1: Yeah, that's a cost and effect, right, basic law of
Speaker 1: the universe. If you wash the dishes, they will presumably
Speaker 1: be clean.
Speaker 2: I wish that same thing applied to physics research. You know,
Speaker 2: you do the physics research and the mysteries are unraveled.
Speaker 2: Doesn't know what's happened that way.
Speaker 1: Well, there's no guarantee in science.
Speaker 2: How about you. Are you a fan of housework?
Speaker 1: Uh? No, And yet I'm the person who does all
Speaker 1: the dishes in my house. Well, actually the dishwasher doesn't,
Speaker 1: but I assist the dishwasher. I'm the assistant dishwasher.
Speaker 2: And are you a fan of vacuuming?
Speaker 1: I'm not a huge fan.
Speaker 2: No.
Speaker 1: I mean, I think my vacuum has a big fan,
Speaker 1: but I am not a fan of vacuuming.
Speaker 2: I agree vacuuming totally sucks.
Speaker 1: Hi. I'm Horium, my cartoonist and the author of all
Speaker 1: ours great big Universe.
Speaker 2: Hi. I'm Daniel. I'm a particle physicist and a professor
Speaker 2: at U. See Irvine, and sometimes I feel like my
Speaker 2: head contains a perfect vacuum.
Speaker 1: You mean, like a perfect vacuuming machine or a perfect
Speaker 1: lack of pressure.
Speaker 2: You know how, sometimes you reach back into your mind
Speaker 2: for a good idea and you just find nothing. On
Speaker 2: the other hand, you know, maybe that means you're ready
Speaker 2: to suck in a bunch of new information.
Speaker 1: M I thought you were saying your brain sucks.
Speaker 2: The creative process is a mystery to me.
Speaker 3: You know.
Speaker 2: Sometimes you reach back there and you find gold, and
Speaker 2: other times you are just left empty handed.
Speaker 1: It is pretty dusty inside of my head as well.
Speaker 1: But anyways, welcome to our podcast, Daniel and Horror I
Speaker 1: Explained Universe, a production of iHeartRadio.
Speaker 2: In which we try to take the whole universe and
Speaker 2: squeeze it into your brain, hoping that there's enough space
Speaker 2: to contain all of its mysteries, all of its majesty,
Speaker 2: all of its marvelous contents, including quantum particles, including black holes,
Speaker 2: including neutron stars, including photons, and everything else that makes
Speaker 2: this universe a wonderful, delicious and bizarre place to live.
Speaker 1: That's right. It is science's job to dig down into
Speaker 1: the dusty corners of the universe and polish off our
Speaker 1: knowledge about how things work and why things are the
Speaker 1: way they are.
Speaker 2: And when scientists think about dust, we're not always just
Speaker 2: thinking about it as an annoyance, something to get rid of. Instead,
Speaker 2: we want to take the universe apart into its smallest pieces,
Speaker 2: and so dust provides a very useful clue. What is
Speaker 2: dust made out of? What happens when we break dust
Speaker 2: open into smaller bits? Why is the universe so dusty? Anyway?
Speaker 1: So we are actually technically all made out of star dust, right,
Speaker 1: isn't that what the famous saying from Carl Sagan?
Speaker 2: That is the famous saying. And you know it's mostly true.
Speaker 2: All the heavier elements we were made of, at least
Speaker 2: were composed in the hearts of stars out there, fusing
Speaker 2: together the primordial hydrogen and helium created during the Big Bang.
Speaker 2: But since a large part of our bodies are made
Speaker 2: of hydrogen, part of us are actually Big Bang dust,
Speaker 2: not just star dust.
Speaker 1: I guess maybe since atoms are all made of the
Speaker 1: same things, technically, like, it's just more and more dust,
Speaker 1: kind of compounded dust that we're made out of.
Speaker 2: Jorges Dusty theory of the Universe.
Speaker 1: Now, does that mean that bunnies are also made out
Speaker 1: of dust bunnies?
Speaker 2: Or are dust bunnies made out of bunnies?
Speaker 1: How about people named dusty? Would they also be made
Speaker 1: out of star dust?
Speaker 2: Star dust and bang dust? And while it's fun to
Speaker 2: make these jokes, it's also really a fascinating mystery, like
Speaker 2: what is all of this stuff? What is its fundamental nature?
Speaker 2: Deep down? And that question is sitting inside a deeper, broader,
Speaker 2: maybe even emptierestion, which is like, what is all of
Speaker 2: this stuff sitting in? What happens to the universe if
Speaker 2: you get rid of all the dust, you finally suck
Speaker 2: it all away and reveal the nothingness? What is all
Speaker 2: of that nothingness?
Speaker 1: That's right? What is nothing? Is it nothing? Or is
Speaker 1: nothing something?
Speaker 2: Do we have nothing to say about it? And can
Speaker 2: we anyway spin it into a forty five minute podcast?
Speaker 1: No, let's just create an audio vacuum right now for
Speaker 1: forty five minutes. Ready go.
Speaker 2: That's actually a great analogy for today's podcast because even
Speaker 2: in that quiet, pun free moment, there was not nothing.
Speaker 2: There was something.
Speaker 1: So today on the podcast, we'll be asking the question
Speaker 1: what is a vacuum?
Speaker 2: Now?
Speaker 1: I imagine Daniel, you mean like a space vacuum, not
Speaker 1: like a household vacuum.
Speaker 2: I do love digging into the physics of everyday objects,
Speaker 2: because it turns out there's always a surprising amount of
Speaker 2: complicated physics that goes into like what is a mirror?
Speaker 2: Or how does glass work? This kind of stuff is
Speaker 2: super fun. But no, today, I want to talk about
Speaker 2: the nothingness of the universe. What happens if you use
Speaker 2: a vacuum to suck up all this stuff? What is
Speaker 2: that vacuum? And philosophically, what does that mean about the
Speaker 2: nature of reality?
Speaker 1: Yeah, and I guess more fundamentally, does a vacuum exist?
Speaker 1: Is it possible to actually have nothing in the universe?
Speaker 2: Or is it possible to have multiple different vacuums or
Speaker 2: vacuum a.
Speaker 1: Or maybe more a trippy Is a vacuum something.
Speaker 2: Or if a vacuum is something, maybe that's just what
Speaker 2: we define as nothing as the most vacuum meist something.
Speaker 1: Okay, now I'm getting nothing out of this.
Speaker 2: I just invented a word vacuumist. Vacuumist, though it sounds
Speaker 2: more like somebody who operates a vacuum. Maybe it's not
Speaker 2: the best choice.
Speaker 1: Well, that would be a vacuumer, wouldn't it be?
Speaker 2: Not an expert in naming things over here?
Speaker 1: Very clearly, But anyways, as usual, we were wondering how
Speaker 1: many people out there had thought about this fundamental question
Speaker 1: what is a vacuum and if they have any ideas
Speaker 1: about whether it is something or nothing.
Speaker 2: So thanks very much to everybody out there who answers
Speaker 2: these questions for the podcast. And if you've been listening
Speaker 2: for a while or even just a few weeks and
Speaker 2: you'd like to throw your hat into the ring, everybody's welcome,
Speaker 2: please write to me two questions at Danielandjorge dot com.
Speaker 1: So think about it for a second. What do you
Speaker 1: think a vacuum is? Here's what people have to say.
Speaker 4: It sounds like the inside of my head when you
Speaker 4: ask this question, But if I were to think of it,
Speaker 4: vacuum is like a whiteboard with infinite possibilities, And when
Speaker 4: something comes along, like a whiteboard marker, you can either
Speaker 4: draw stuff on it or you can just raise stuff
Speaker 4: on it.
Speaker 1: It's just everything.
Speaker 5: The vacuum would be space without any stuff in it,
Speaker 5: like no atmosphere, but I think space always has some
Speaker 5: stuff in it, so it's not really a true vacuum.
Speaker 5: That's really all I know.
Speaker 1: I'm pretty sure the vacuum is like space with all
Speaker 1: its quantum fields, like at its resting state.
Speaker 3: I can guess by what it says the vacuum is
Speaker 3: not a vacuum cleaner, but the vacuum of space. What
Speaker 3: causes it is actually a good question. I don't know.
Speaker 3: Maybe it's something related to dark energy and expansion, but
Speaker 3: probably not.
Speaker 4: I think vacuum is the definition, the theoretical definition of
Speaker 4: the absence of matter in a given space.
Speaker 6: I think vacuum quite literally means emptiness or absence of stuff. Now,
Speaker 6: if you have a bottle, you remove everything from it,
Speaker 6: then you have a vacuum. But I think that's pretty ideal.
Speaker 2: I don't think you can actually remove everything from a bottle.
Speaker 6: Vacuum is the absence of matter, but I know that
Speaker 6: it doesn't mean it's empty, and there are lots of
Speaker 6: quantum craziness going around in what we traditionally call vacuum.
Speaker 6: So I'm looking forward for your guys to explain it.
Speaker 1: All right, A lot of interesting answers here. Someone got
Speaker 1: kind of technical talking about fields and resting states, the
Speaker 1: absence of matter.
Speaker 2: M m lots of really cool answers here that explore
Speaker 2: really the wide spectrum of possibilities for what nothing is.
Speaker 1: Yeah, I guess you could define it in several ways, right,
Speaker 1: like absence of matter or absence of energy, or absence
Speaker 1: of quantum field maybe.
Speaker 2: Yeah, And we will tear all of that apart on
Speaker 2: the podcast today.
Speaker 1: Well, let's dig into it, Daniel. How does physicists define
Speaker 1: what a vacuum is?
Speaker 2: So, the definition of a vacuum, from the point of
Speaker 2: view of physics and especially quantum field theory, is space
Speaker 2: with no particles in it. Essentially space as empty as
Speaker 2: possible from energy. If you can stuck all the energy out,
Speaker 2: including the matter, and relax space down to its lowest
Speaker 2: energy state, that's what we consider a vacuum.
Speaker 1: Now, how is it different than the concept of space itself.
Speaker 1: Is space the vacuum or can space be a vacuum?
Speaker 2: Well, there's the difference between space and sort of empty space.
Speaker 2: Space itself doesn't have to be a vacuum. Like at
Speaker 2: the heart of the Sun. There's space, right, there's all
Speaker 2: sorts of particles bouncing around, whizzing around, incredible density, very
Speaker 2: high temperature, lots of matter loss of energy. All of
Speaker 2: that sits within space. Right, the Sun is in space.
Speaker 2: Even the heart of the Sun has space within it.
Speaker 2: It's not empty space. It's very high energy, very dense space.
Speaker 2: As you move away from the Sun, of course, that
Speaker 2: space gets lower and lower energy, fewer particles. But everywhere
Speaker 2: in the universe we think has space in it.
Speaker 1: You mean everywhere in space has space in it.
Speaker 2: Yeah. As soon as you use the word where, you're
Speaker 2: assuming a location and location requires space. You can't really
Speaker 2: have locations without space. Space represents the relationships between points, right,
Speaker 2: That's really what space is.
Speaker 1: I guess can you have the universe without space or
Speaker 1: space without universe?
Speaker 2: You might be able to have the universe without space
Speaker 2: because we don't fundamentally know what space itself is. We
Speaker 2: don't know if it's a necessary fundamental part of the universe,
Speaker 2: meaning that like it has to exist, or if it's
Speaker 2: an emergent property of something deeper, you know, something that
Speaker 2: just sort of gets woven together out of the fundamental
Speaker 2: bits of the universe that might not require space. If
Speaker 2: you're not familiar with the concept of like fundamental versus emergent,
Speaker 2: fundamental just means it's required, it's essential, whereas emergent means
Speaker 2: it's not that. Sometimes it happens and sometimes it doesn't.
Speaker 2: Like ice cream and pies we think are emergent properties
Speaker 2: or something the universe can do, they can't exist. But
Speaker 2: it's possible to have a universe without ice cream and pies.
Speaker 2: So we think it might be possible to have a
Speaker 2: universe without space, though that's not something we understand. There
Speaker 2: are various theories out there, but that's an open question
Speaker 2: in physically, so far we're operating under the assumption that
Speaker 2: space is essential for the universe.
Speaker 1: Well, I don't know about physics, but ice cream is
Speaker 1: pretty essential to my life. I mean, a universe without
Speaker 1: ice cream it's not a universe I want to live in.
Speaker 2: And yet the vast majority of the history of the
Speaker 2: universe had exactly zero ice cream in it, unless, of course,
Speaker 2: there are ancient alien civilizations who also enjoyed cold custards.
Speaker 1: We don't know. So you're saying you don't know if
Speaker 1: aliens have ice cream or not. It's still an open question.
Speaker 2: I can make no definitive statement about alien ice cream
Speaker 2: that is exactly true.
Speaker 1: Yes, Also, I think in a vacuum, no one can
Speaker 1: hear you ice cream. You're like, I don't even know
Speaker 1: where to go with that joke.
Speaker 2: That was the perfect joke. There's no possible response to it.
Speaker 2: A vacuum is there only possible response to that joke.
Speaker 1: That's right, it's a micdrop moment.
Speaker 2: Boom, Exactly, I just dropped my ice cream over here.
Speaker 2: It's an ice cream drop moment.
Speaker 1: But ana is back to our discussion. So you're saying
Speaker 1: a vacuum is space with no matter in it, no
Speaker 1: particles in it.
Speaker 2: Yeah, that's exactly right. Whereas the minimum energy which includes particles. Right,
Speaker 2: if you're talking about what space is, space is fundamentally
Speaker 2: something we don't understand, but it has inside of it
Speaker 2: the possibility to contain all sorts of energy and matter.
Speaker 2: You can have protons in space. You can have photons
Speaker 2: in space. Photons are not technically matter, they fall into
Speaker 2: the radiation category. Right, So you can all sorts of
Speaker 2: different kinds of energy inside of space, and we have
Speaker 2: a huge variety of energy. Density in space. Right around
Speaker 2: us on Earth is an incredible number of particles. You
Speaker 2: take a cubic meter of air just in front of
Speaker 2: you here on Earth, and there's like ten to the
Speaker 2: twenty five mongules in that cubic meter of air. It's
Speaker 2: like swarming with particles.
Speaker 1: Well, I guess you know, for me traditional Newtonian kind
Speaker 1: of high school physics, or you know, kind of as
Speaker 1: we grow up kind of way. A particle are bits
Speaker 1: of stuff that can fly around or float around, and
Speaker 1: so it's kind of easy to imagine just a chunk
Speaker 1: of space, a Cuba space, with no little bits in it. Right,
Speaker 1: that would be a vacuum in a traditional sense.
Speaker 2: In a traditional sense depending on whether you're including radiation also, right,
Speaker 2: To really get a vacuum, you want to minimize the
Speaker 2: overall energy, not just the total matter. So yeah, you
Speaker 2: want to apply your vacuum and suck out all the bits.
Speaker 2: But then you also want to prevent photons and other
Speaker 2: kinds of non matter radiation from entering that cube of
Speaker 2: space to get the best vacuum you can get.
Speaker 1: Well, radiation is also particles, right, Like a photon is
Speaker 1: a particle.
Speaker 2: A photon is a particle, but it's not matter in
Speaker 2: the same sense. These are like silly overlapping definitions. So yeah,
Speaker 2: if you suck out all the particles, that would include photons.
Speaker 2: So yes, that would be all the radiation.
Speaker 1: But I guess it's complicated because now we know that
Speaker 1: a particle is really just like a little blip in
Speaker 1: a quantum field. Right.
Speaker 2: So there are sort of two different philosophical pictures about
Speaker 2: how this all works, and one that we talk about
Speaker 2: on the podcast a lot is what you just described,
Speaker 2: which is to meagine particles themselves as emergent properties. They're
Speaker 2: not fundamental things in the universe. They're just eagles in
Speaker 2: these fields that fill all of space. And in that picture,
Speaker 2: fields are the most fundamental thing that when you have space,
Speaker 2: it contains these fields. And these fields are like places
Speaker 2: that energy can be. They're like, you know, how you
Speaker 2: can stack energy up and if you wiggle them in
Speaker 2: just the right way, then we call that a particle.
Speaker 2: So that's sort of one picture of the structure of space, time,
Speaker 2: and matter. There's another picture which says fields are nonsense.
Speaker 2: Really everything is made of particles, and the way particles
Speaker 2: communicate with each other and exchange momentum and stuff is
Speaker 2: by exchanging other particles. So the sort of the fields picture,
Speaker 2: which I think is more popular and maybe more intuitive,
Speaker 2: But there is also this other picture that says that
Speaker 2: particles are the most fundamental thing, and fields are nonsense
Speaker 2: because remember, we never actually see fields themselves. Fields are
Speaker 2: sort of a unobserved story. We tell ourselves to explain
Speaker 2: what we do see in the universe, but we never
Speaker 2: actually see them. We only see their effect on particles.
Speaker 1: Fields are sort of like the potential for particles to happen.
Speaker 2: Yeah, there's sort of like the parking lot into which
Speaker 2: you can put cars, right, but again, we can't ever
Speaker 2: see them directly, like even electric field which don't seem
Speaker 2: controversial as a topic, like do electric fields exist? Well,
Speaker 2: how do you see an electric field? You put an
Speaker 2: electron in it and you see it move. What you're
Speaker 2: really seeing is the electron moving, not the field itself,
Speaker 2: So it's sort of a little bit indirect.
Speaker 1: Well, maybe we're getting a little bit ahead of ourselves.
Speaker 1: I think what you're saying is that the idea that
Speaker 1: a vacuum is just a chunk of space without particles
Speaker 1: in it's still or energy is still pretty good.
Speaker 2: Yeah, that's a pretty good concept of what a vacuum is,
Speaker 2: though it's surprisingly rare in the universe and hard to achieve.
Speaker 1: Well, I guess maybe the first question or listeners might
Speaker 1: have is is space out there really a vacuum.
Speaker 2: It's hard for me to say that anywhere in the
Speaker 2: universe is actually a true vacuum. If you go like
Speaker 2: near the surface of the Earth where space officially starts,
Speaker 2: which is like one hundred kilometers above the surface of
Speaker 2: the Earth, although the United States calls you an astronaut,
Speaker 2: if you've been above eighty kilometers, then that's where space
Speaker 2: officially starts. But there's a lot of stuff out there still.
Speaker 2: You know, the Earth's atmosphere doesn't end. It's not like
Speaker 2: there's a pane of glass there that's holding the atmosphere
Speaker 2: and it should drifts off gradually. So there's still a
Speaker 2: lot of atmosphere up there. And if you fly your
Speaker 2: satellite at that orbit, you'll be dragged by that atmosphere
Speaker 2: and eventually you deorbit back to the Earth's surface. So
Speaker 2: we know that there's definitely a lot of stuff out
Speaker 2: there still.
Speaker 1: Just about the Earth or just outside of the Earth.
Speaker 1: It's kind of you say, it's kind of hard to
Speaker 1: find a true vacuum.
Speaker 2: And so you go further, right like, Okay, I'm gonna
Speaker 2: leave Earth entirely, I'm gonna go into interplanetary space. Halfway
Speaker 2: between Earth and Mars. Well, then there's still a lot
Speaker 2: of stuff out there. You know, the Sun pumps out
Speaker 2: not just photons which we consider energy and particles and
Speaker 2: so it disrupts your vacuum, but also matter particles, electrons, protons,
Speaker 2: alpha particles, very very high speed particles moving on like
Speaker 2: hundreds of kilometers per second. And there's not a tiny
Speaker 2: number of them. There's like millions of protons per cubic
Speaker 2: meter out there in interplanetary space.
Speaker 1: Whoa coming from the Sun, right.
Speaker 2: Yeah, this is the solar wind. And you know that's
Speaker 2: a tiny number compared to the density of air here
Speaker 2: on Earth. It's like ten to the nineteen times less dense.
Speaker 2: So it feels like a vacuum if somebody chucks you
Speaker 2: out the air lock, But it's not even really close
Speaker 2: to a vacuum because you still have millions of particles
Speaker 2: per cubic meter.
Speaker 1: Well, what if you go out further into space. Can
Speaker 1: you find a true vacuum out there?
Speaker 2: If you like leave the Solar System and go into
Speaker 2: interstellar space, still inside the galaxy, then you're still surrounded
Speaker 2: by what we call the interstellar medium, which is mostly
Speaker 2: gas and a little bit of dust some cosmic rays,
Speaker 2: and here it's much more sparse and it's highly variable.
Speaker 2: You can get from like ten to the minus four
Speaker 2: up to ten to the six molecules per cubic meter,
Speaker 2: so it's still really not close to empty. And don't
Speaker 2: forget that's just the kind of matter we know about, right,
Speaker 2: protons and electrons. There's still also the dark matter, which
Speaker 2: is filling the galaxy. Inside the galley, we're inside the
Speaker 2: dark matter halo, which is five times as much matter
Speaker 2: as the normal matter. So inside the galaxy you can't
Speaker 2: really ever say you have a vacuum.
Speaker 1: What about like the far reaches of space, Like if
Speaker 1: you go deep out there in the middle of nowhere,
Speaker 1: really in the middle of nowhere between galaxies.
Speaker 2: So take a point, for example, between the Milky Way
Speaker 2: and Andromeda. You're far outside of the galaxy. There's still
Speaker 2: something there. There's the intergalactic medium. This is a rarefied plasma.
Speaker 2: It's mostly protons and it's not zero. There's like one
Speaker 2: to ten atoms per cubic meter, and there's actually kind
Speaker 2: of a lot of stuff out there, this plasma that's
Speaker 2: between galaxies. This number sort of shocks me. Is about
Speaker 2: half of the ordinary matter in the universe. Like you
Speaker 2: look up at the night sky and you see stars,
Speaker 2: and you think about galaxies, and you know, there's a
Speaker 2: lot of dark matter out there that we can't see,
Speaker 2: but you imagine probably we're seeing all the normal matter.
Speaker 2: But something like half fifty percent of all the normal
Speaker 2: matter in the universe is between galaxies, any sort of
Speaker 2: filaments of plasma that connects them together.
Speaker 1: Yeah, because these filaments are huge, right, Like the space
Speaker 1: between galaxies and clusters of galaxies. It's a lot. So
Speaker 1: even if you only have one to ten atoms per
Speaker 1: cubic meter, it adds up to as you're saying, half
Speaker 1: of the stuff in the universe.
Speaker 2: Yeah, it's really a lot of stuff. But you can
Speaker 2: get more sparse. Right, You're like, let's not hang out
Speaker 2: between the galaxies. Let's leave the galactic cluster, or let's
Speaker 2: find one of these supervoids that are between the superclusters.
Speaker 2: Right and out there is the closest you can get
Speaker 2: to a vacuum. You know, the number density of particles,
Speaker 2: the particles per cubic meter drops to almost zero. There's
Speaker 2: almost no photons out there either. It's like as close
Speaker 2: to zero as you can.
Speaker 1: Get wait, isn't that weird? Like how can you have
Speaker 1: no photons? Like you'd be there and you would look
Speaker 1: out around you and you wouldn't see anything.
Speaker 2: It'll never actually get to zero. Right, You'll be as
Speaker 2: distant as possible from all of those galaxies, and so
Speaker 2: you'll have the dimmest view of all of them. But
Speaker 2: you're right, it'll never actually get to zero. Right. It's
Speaker 2: not like you look around you and you see total blackness.
Speaker 2: So the number of photons will never actually get to zero,
Speaker 2: even inside those supervoids. It's like the furthest you can
Speaker 2: get from all the light sources. It's like if you're
Speaker 2: trying to find a dark spot in your city to
Speaker 2: look at the night sky, and you get as far
Speaker 2: away as possible from all the street lights, you're still
Speaker 2: going to have some light there.
Speaker 1: Are you trying to say that there is no perfect
Speaker 1: vacuum in the universe, naturally occurring perfect vacuum in the universe.
Speaker 1: It's not possible to find a perfect vacuum.
Speaker 2: It's probably impossible for all of those reasons. I think
Speaker 2: every chunk of space probably has at least one photon
Speaker 2: in it from some distant galaxy that threw that particle
Speaker 2: in that direction.
Speaker 1: But that's kind of an average though, right, Like, maybe
Speaker 1: when you're out there, you see a photon every once
Speaker 1: in a while, but in between the times that you
Speaker 1: see a photon, you would be sort of in a
Speaker 1: perfect vacuum potentially.
Speaker 2: And here's where we run up against the technical question,
Speaker 2: because every chunk of space also contains dark energy, right.
Speaker 2: Dark energy not something we understand, but every chunk of
Speaker 2: space has some of it. So the technical definition of
Speaker 2: a vacuum is not space with no energy in it.
Speaker 2: It's space with a minimum amount of energy. So you
Speaker 2: can be in a chunk of space that has some
Speaker 2: energy in it and still call that a vacuum if
Speaker 2: you're convinced that that's the most relaxed possible state of space.
Speaker 1: Hmm. It sounds like maybe there's a concept of a
Speaker 1: perfect vacuum, and then there's a concept of like what's
Speaker 1: the minimum vacuum that the universe naturally has out there?
Speaker 1: You know, kind of like temperature, right, Like there's absolute zero,
Speaker 1: and then there's what actually actually seen the universe.
Speaker 2: There's what space theoretically could accomplish in terms of relaxation,
Speaker 2: and then there's this sort of most relaxed space that
Speaker 2: actually exists in the universe, and those could be different.
Speaker 1: Hmm. All right, so let's get into what would actually
Speaker 1: happen if you create a perfect vacuum in the universe.
Speaker 1: What would that mean? Is it possible and would it
Speaker 1: be as tidy as we want it to be? Dig
Speaker 1: into that, But first let's take a quick break. All right,
Speaker 1: we're talking about vacuuming the universe. It sounds like the
Speaker 1: universe has a lot of space that you need to
Speaker 1: suck up.
Speaker 2: It's a big chore to clean up the whole universe.
Speaker 1: Now, is the universe more of like a shag carpet
Speaker 1: or you think it's more of a wooden floors kind
Speaker 1: of situation.
Speaker 2: I think it'd be pretty hard to totally thoroughly cleanse
Speaker 2: the universe, So yeah, it's definitely shag carpeting out there.
Speaker 1: Or maybe right like, we don't know if maybe the
Speaker 1: universe encompasses all of the matter in the universe, or
Speaker 1: maybe there's a bunch of universe out there that is
Speaker 1: truly empty.
Speaker 2: It's possible, though cosmologists prefer the assumption that the universe
Speaker 2: is essentially the same everywhere. It's not a totally solid
Speaker 2: experimental point, but it's sort of the simplest idea that
Speaker 2: there's no special place in the universe. And so when
Speaker 2: you zoom out really far and cosmic scales, we see
Speaker 2: so far the universe has the same density of stuff
Speaker 2: basically everywhere, again massively zooming out right on the scale
Speaker 2: of superclusters of galaxies. So that would suggest that there
Speaker 2: isn't any place in space that's like really truly specially empty,
Speaker 2: different from the part of the universe that we find
Speaker 2: ourselves in. So that's just an assumption, right, which is
Speaker 2: extrapolating from what we see out to infinity, which is
Speaker 2: always dangerous.
Speaker 1: Yeah. I think sometimes people talk about the analogy with
Speaker 1: like fish in the water, right, Like you could be
Speaker 1: a fish at the bottom of the ocean and think, oh,
Speaker 1: the whole universe is filled with water, right, because as
Speaker 1: far as I can see, there's water.
Speaker 2: Yeah, that's right. I think that's Max tech Mark's analogy,
Speaker 2: which is really wonderful because it gives you a sense
Speaker 2: of your naivete and how you might not know what
Speaker 2: you don't know. And there could of course be boundaries
Speaker 2: to the kind of universe that you imagine we could
Speaker 2: be living in a bubble where these laws of physics
Speaker 2: apply and everything seems to make sense to us, but
Speaker 2: there could be an edge to it out past, which
Speaker 2: the universe is in another phase, you know, crazy densities
Speaker 2: where quantum gravity applies, or maybe the inflaton field hasn't
Speaker 2: decayed yet, or some other crazy nosis, so it's always possible.
Speaker 1: Or maybe we're living inside of a vacuum of someone
Speaker 1: cleaning up their universe in a super mega universe.
Speaker 2: Man, that would totally suck so well.
Speaker 1: As you were saying earlier, it's kind of hard to
Speaker 1: find a naturally occurring perfect vacuum because even if you're
Speaker 1: out there in the depth of space in between galactic clusters,
Speaker 1: there's stills kind of stuff in it. There might be
Speaker 1: some a little bit of light or an atom here
Speaker 1: or there, or maybe even dark energy or dark matter.
Speaker 2: Right, Yeah, that's right. It's hard to find a chunk
Speaker 2: of space that really has no particles in it because
Speaker 2: the universe is buzzing with stuff and that's flying everywhere
Speaker 2: and filling everything up.
Speaker 1: So then I guess the next question that we can
Speaker 1: ask is is the perfect vacuum possible? And what would
Speaker 1: it look like, like, can you have a chunk of
Speaker 1: space with that any particle, matter or energy in it?
Speaker 1: What's left if you have none of that?
Speaker 2: Yeah, So imagine that you were able to somehow rid
Speaker 2: a chunk of space of all the particles. Maybe you
Speaker 2: built a box that blocked all photons another matter from entering,
Speaker 2: and you sucked everything out of it. What would be
Speaker 2: in there? Right? What is sort of the nature of nothing?
Speaker 2: What is the minimum thing that exists in the universe?
Speaker 2: Or like, what is reality when there's nothing in it?
Speaker 2: And you know, we don't know the answer to that
Speaker 2: question at the deepest level, but we do have a
Speaker 2: theory that describes it. Right. We call that thing space,
Speaker 2: and space still has a structure to it even if
Speaker 2: you suck all the stuff out of it. Right, This
Speaker 2: is what we were talking about earlier, that there's a
Speaker 2: possibility for things to exist, and that possibility are the fields.
Speaker 2: We think of these as part of space itself, That
Speaker 2: these fields exist even when there's nothing in them, that
Speaker 2: the possibility for things to exist is part of the
Speaker 2: structure of space itself.
Speaker 4: Hmm.
Speaker 1: I guess, as you were saying, it kind of depends
Speaker 1: on what that you consider fields to be a thing
Speaker 1: or not. Like, if you consider them to be a thing,
Speaker 1: then fields kind of take up all of space in
Speaker 1: the universe, right, So you can't have a space without fields.
Speaker 1: But if fields are just kind of a made up concept,
Speaker 1: then it is possible to have empty space.
Speaker 2: If you consider field to be the most fundamental, then yes,
Speaker 2: they are the bedrock. They are contained as part of space.
Speaker 2: They're a fundamental aspect of the universe. And we can
Speaker 2: talk in a minute about like what is the lowest
Speaker 2: energy those fields can occupy, what would that vacuum mean, etcetera,
Speaker 2: et cetera. If you reject fields and say, look, I
Speaker 2: can't ever see fields. I don't think that those really
Speaker 2: are the way particles push on each other, then you
Speaker 2: have another picture, which is virtual particles. Particles push on
Speaker 2: each other by exchanging these virtual particles, you know, and
Speaker 2: two electrons whiz by each other. They're not using their
Speaker 2: fields to push on each other. They're exchanging virtual photons.
Speaker 2: So if you use that picture, you don't just delete
Speaker 2: the field to replace it with nothing else. You delete
Speaker 2: the fields and you replace it with an infinite number
Speaker 2: of virtual particles. So in neither picture of the universe
Speaker 2: is really true empty, even when you have no real
Speaker 2: matter in it.
Speaker 1: Well, is it possible to have space without fields? Right?
Speaker 1: Because fields kind of have come and gone in our
Speaker 1: history of the universe, and also I think mathematically it's
Speaker 1: sort of possible to just not have a field and
Speaker 1: still have space. Right.
Speaker 2: What do you mean fields have come and gone? You
Speaker 2: mean it's a scientific concept, or in the cosmological history
Speaker 2: of the universe.
Speaker 1: I mean, like in the cosmological history right, like you know,
Speaker 1: the Big Bang, we didn't have some of the fields
Speaker 1: we have. Right.
Speaker 2: Our description of the history of the universe goes back really,
Speaker 2: really far to what we think is like a few
Speaker 2: tiny moments in time after maybe the universe was created.
Speaker 2: But it really goes back only as far as we
Speaker 2: can describe with our current laws of physics, and those
Speaker 2: laws always include fields. So it might be that before
Speaker 2: a certain point there weren't fields, But that's because the
Speaker 2: universe is like in a different phase where fields are
Speaker 2: no longer a good description of what's happening, and so
Speaker 2: we use fields as a way to describe the universe
Speaker 2: we're in right now, we don't know if fields are
Speaker 2: fundamental or when the universe changes conditions to a point
Speaker 2: where these laws of physics are no longer relevant that
Speaker 2: some other description is useful. Going back to your fish analogy,
Speaker 2: sort of imagining that the universe currently is in a
Speaker 2: certain phase, like the way the fish are swimming through water,
Speaker 2: and that water is a certain phase, and they develop
Speaker 2: laws of physics that describe, you know, the fluid dynamics
Speaker 2: of that water. If the water was to boil, then
Speaker 2: the water's in a new phase and their laws don't
Speaker 2: work anymore. In the same way, there's a moment before
Speaker 2: which we don't think fields probably describe the phase of
Speaker 2: the universe. We don't know how to describe it requires
Speaker 2: quantum gravity. But from that moment and forward, we think
Speaker 2: fields are a good description of the whole universe. So
Speaker 2: in that sense, yeah, fields haven't always existed, but only
Speaker 2: because this phase of the universe hasn't always existed.
Speaker 1: Well, I guess what I mean is like, if it
Speaker 1: is a phase, it kind of seems optional, kind of
Speaker 1: like the water in the ocean, right, Like, you know,
Speaker 1: you can imagine a universe existing without the muon field
Speaker 1: for example, it's out field or the you know, certain
Speaker 1: quarks or whatever, and you would still maybe have a
Speaker 1: functioning universe, which means maybe they're optional, in which case
Speaker 1: maybe you can have a universe without fields.
Speaker 2: We don't know the answer to that question, right, What
Speaker 2: is the physics of other phases of the universe where
Speaker 2: our laws of physics do not apply. That's a question
Speaker 2: of like what is quantum gravity? You know what happens
Speaker 2: when things get super duper dense and very very hot,
Speaker 2: where gravity is important and quantum mechanics is important. We
Speaker 2: just don't have a theory that describes that. Some candidate
Speaker 2: theories do include fields, right, There's still are fields in
Speaker 2: some of those theories, and so it might be that
Speaker 2: there are still fields back before that moment in time
Speaker 2: when our current theories break down. We just don't know.
Speaker 2: So from that point of view, you don't always have fields.
Speaker 2: But if we're talking about, like what is a vacuum,
Speaker 2: I think that's sort of in the context of our
Speaker 2: current kind of space, the current phase of the universe
Speaker 2: that we're in. You can still say what is a
Speaker 2: vacuum in that context.
Speaker 1: So then I'm trying to figure out what you're trying
Speaker 1: to say. Are you saying that you can not have
Speaker 1: a vacuum a true vacuum. Or are you saying that
Speaker 1: you can't have a vacuum where there's not even fields
Speaker 1: in it, or does your definition of a vacuum just
Speaker 1: includes the fields as a base kind of layer of existence.
Speaker 2: It's that last one. What we consider a vacuum is
Speaker 2: space at its most relaxed, which is what is the
Speaker 2: least energy possible to exist in space. And because our
Speaker 2: concept of space includes these built in fields, they will
Speaker 2: always contain fields. So a vacuum is not perfect zeroness,
Speaker 2: complete emptiness. It's a most relaxed state of space which
Speaker 2: will always include these fields.
Speaker 1: M But I guess, is it theoretically possible to have
Speaker 1: zero energy space?
Speaker 2: It is not theoretically possible because all these fields are
Speaker 2: quantum fields. They're not classical fields like Maxwell's theory of electromagnetism,
Speaker 2: which has like electric and magnetic fields oscillating which makes light.
Speaker 2: Those fields could be absolute zero. You could have them
Speaker 2: at zero energy. You could have zero electric field and
Speaker 2: zero magnetic field. Our modern view is that these fields
Speaker 2: are quantum fields, which means they oscillate differently instead of
Speaker 2: whiggling like a string, where they can take any value.
Speaker 2: There are only certain solutions that are allowed, they're like discretized,
Speaker 2: they're quantized, and the mathematics don't work for zero energy,
Speaker 2: Like the solution of the quantum field equations don't allow
Speaker 2: a zero energy solutions. It's like a minimum energy required
Speaker 2: for any quantum fields. They have to be like bubbling
Speaker 2: and frothing at some tiny little level, at the very minimum.
Speaker 1: I guess maybe what I'm asking it at a fundamental
Speaker 1: level is can you have a universe with no fields?
Speaker 2: Are you asking whether we could have a universe with
Speaker 2: fields that are at zero or a universe where space
Speaker 2: literally does not have the capacity for fields.
Speaker 1: Can you have a universe where there are no fields
Speaker 1: in it?
Speaker 2: That? We don't know? Right? Our current definition of space
Speaker 2: has these fields built in. Is it possible to have
Speaker 2: another kind of space without fields, where you wouldn't even
Speaker 2: have the possibility to have matter in it? We don't know.
Speaker 2: We don't even know what that would mean, right, because
Speaker 2: you can't have things in it. What does distance really mean?
Speaker 2: If space is by definition empty, distance is sort of
Speaker 2: defined to be between two locations, right, So that would
Speaker 2: be like a whole new kind of space, one that
Speaker 2: doesn't even have the capacity to have stuff in it.
Speaker 1: But that does a math allow for it, or does
Speaker 1: a math not only exist, like the math we have
Speaker 1: only exists or is defined in a universe with fields
Speaker 1: in it.
Speaker 2: You could create a conceptual space with no fields in it.
Speaker 2: Sure it's trivial, right, Like, there's no math for it,
Speaker 2: there's nothing in it. Right, So it's just like it's
Speaker 2: like writing nothing on a sheet of paper. That's your theory.
Speaker 1: Well, yeah, I mean kind of right. Well there's a paper, right,
Speaker 1: the paper exists, you're just not putting an equation in it,
Speaker 1: or you're writing zero in it.
Speaker 2: Yeah, zero, right? But what is zero like is that
Speaker 2: you have a field whose value is zero? If you're
Speaker 2: talking about like really true empty of any theoretical content
Speaker 2: that can exist. Theoretically, it doesn't describe anything in our universe. Right,
Speaker 2: All these concept have to make contact with reality. So
Speaker 2: our best description of reality as we see it out
Speaker 2: there is space that always has fields in it, and
Speaker 2: those fields are never at zero energy. We've never discovered
Speaker 2: any evidence for fieldless space. Theoretically you can make that concept, sure,
Speaker 2: but we don't think it describes reality.
Speaker 1: I see. So I think what you're saying is that
Speaker 1: the universe that we see out there has fields in it,
Speaker 1: and therefore there's no such thing as perfect nothingness because
Speaker 1: everything we see has fields in it.
Speaker 2: Yeah, if perfect nothingness as things without fields, then we
Speaker 2: don't think that exists. In the universe. Every chunk of
Speaker 2: space has those fields, and those fields have some zero
Speaker 2: point energy, some minimum fuzziness, some oscillation to them. For example,
Speaker 2: the Higgs field feels all of space, and the Higgs
Speaker 2: field is sort of weirdly stuck at high energy, so
Speaker 2: it's not a trivial amount of energy that's in space
Speaker 2: even when there's no matter in it.
Speaker 1: But I think what you mean by like everywhere there
Speaker 1: has this little bit of energy to it, you don't
Speaker 1: mean like there's actually energy there. I think what you
Speaker 1: mean is that there's kind of like the potential for
Speaker 1: there to be things in it, or like the universe
Speaker 1: leans towards stuff being there.
Speaker 2: No, I mean there's literally energy in space. The Higgs field,
Speaker 2: for example, filled space, and it has a high potential energy.
Speaker 2: Even if there are no particles there. There is energy
Speaker 2: in the configuration of the field itself.
Speaker 1: That's what I mean. I think you said it has
Speaker 1: the potential to do stuff it's a potential energy. It's
Speaker 1: not like a little photon floating out there in space.
Speaker 2: That's right, it's potential energy exactly. It's like if you
Speaker 2: mentioned a guitar string. Somebody has pulled the guitar string
Speaker 2: away from its relaxed state and it's taught, so it's
Speaker 2: storing energy in that. It's not moving. There's no kinetic
Speaker 2: energy right now. It's not oscillating, but it's held in
Speaker 2: a configuration that has energy. If somebody was to release it,
Speaker 2: it would vibrate and make a noise. Right. The Higgs
Speaker 2: field is just like that. It's held in some configuration
Speaker 2: that stores a lot of energy, and that's potential energy.
Speaker 2: But every field has some energy in it, not even
Speaker 2: just the Higgs field, Like the electromagnetic field that feels
Speaker 2: space is held in a non zero value and that's
Speaker 2: not just potential energy. That's like actually thrumming with kinetic energy.
Speaker 1: Thruw I mean in a quantum says that. I think
Speaker 1: what you mean is like there's like quantum particles popping
Speaker 1: in and out of existence. Is that what you mean?
Speaker 2: Not enough energy to make a real particle, But the
Speaker 2: field itself has energy. It is vibrating. You can think
Speaker 2: of these fields as having kinetic energy and potential energy,
Speaker 2: just like a string, right, which slides back and forth
Speaker 2: between having kinetic and potential energy as it oscillates. So
Speaker 2: these fields have actual energy, not enough to make a particle. Right,
Speaker 2: The lowest energy state of these things is not one particle.
Speaker 2: It's zero particles, but not zero energy.
Speaker 1: All right, So then what does that mean for the
Speaker 1: idea of a vacuum. Means that in our universe you
Speaker 1: can have a perfect vacuum.
Speaker 2: In our universe, we define sort of theoretical concept is
Speaker 2: the most relaxed state of all the fields. That's sort
Speaker 2: of like how we define a vacuum. We don't define
Speaker 2: it to be like the theoretical minimum where all the
Speaker 2: fields are a zero, because that's not theoretically possible. We
Speaker 2: consider this sort of state of space as we understand
Speaker 2: it and try to imagine what would be the most
Speaker 2: relaxed configuration that all the field could get into. And
Speaker 2: we now know that that's not at zero. But what's
Speaker 2: interesting is that there might be multiple ways for the
Speaker 2: field to relax. There might be a few stable configurations.
Speaker 2: One of those would be the true vacuum. The actual
Speaker 2: lowest possible state. The other ones would be false vacua
Speaker 2: like places that space gets stuck as it's trying to
Speaker 2: relax down to zero and it ends up in a
Speaker 2: stable configuration that's not actually the lowest energy state.
Speaker 1: I think what you're saying is that, like even if
Speaker 1: you go out there in the middle of space, or
Speaker 1: even if you create one, like you make a box
Speaker 1: where nothing can get in it and there's no particles,
Speaker 1: you see, no particles in it, there is still a
Speaker 1: little bit of like thrumbing or a little bit of
Speaker 1: vibration of the fields in that space not creating fully particles,
Speaker 1: Like there's not enough there to actually pop out a
Speaker 1: particle with that you can see and interact with. But
Speaker 1: there's like, you know, half a particle forming and then
Speaker 1: it's gone. There's a quarter of a particle Thereah, but
Speaker 1: it's gone. Kind of situation, right.
Speaker 2: Yeah, And you just intuited your way from the field
Speaker 2: description to the particles cold description, Like what does the
Speaker 2: energy of this field mean if it's not enough to
Speaker 2: have an actual particle there. Well, it's sort of like
Speaker 2: you know the particles exist, and that they don't they
Speaker 2: pop in and out of existence. That's replacing the idea
Speaker 2: of a field with these virtual particles that have some
Speaker 2: weird energy from space itself and not enough to really
Speaker 2: exist in the sense of like it could hang out
Speaker 2: and you could leave the electron there and come back
Speaker 2: a billion years later it would still be there. These
Speaker 2: are virtual particles. That's sort of intuitive way to think
Speaker 2: about what a virtual particle is, just like another way
Speaker 2: to think about a field. When the field doesn't have
Speaker 2: enough energy to make real particles, it might have enough
Speaker 2: to make virtual particles.
Speaker 1: All right, well, let's get into the idea of what
Speaker 1: it would mean if you actually created a real vacuum,
Speaker 1: and it has to do with this concept of a
Speaker 1: fields relaxing. How relax can you make a field? What
Speaker 1: sort of medication you need to give it in order
Speaker 1: for it to finally relax. We'll dig into that, but
Speaker 1: first let's take another quick break. All right, we're talking
Speaker 1: about nothing today. This is the episode about nothing.
Speaker 2: This is the Seinfeld of podcast.
Speaker 1: That's right. I'll be Kramer and you be Which one
Speaker 1: of us is Kramer, Which one of them is George? Consensus.
Speaker 2: I think you're definitely more Kramer and I'm more George.
Speaker 2: For sure. I always wanted to be an architect.
Speaker 1: Yeah, I thought I was a comedian. Wait a minute,
Speaker 1: but we were talking about nothing and the idea of
Speaker 1: nothing and whether it's possible to have nothing in the universe,
Speaker 1: and it sounds like that's not really possible. In the
Speaker 1: universe that we see and experience, there are things called
Speaker 1: quantum fields and so you which occupied all of space
Speaker 1: and which has kind of inherent energy to it. So
Speaker 1: there's really no trunk of space out there that has
Speaker 1: zero energy.
Speaker 2: Yeah, that's right. Space has these fields and they're always
Speaker 2: wiggling at least a little bit. And so instead of
Speaker 2: thinking about true zeroness of space, which we think is impossible,
Speaker 2: physicists like to think about the minimum energy state of space.
Speaker 2: That's what we call the vacuum, what happens when space
Speaker 2: relaxes as much as it's theoretically allowed.
Speaker 1: Okay, so then I guess we're this more like maximum
Speaker 1: vacuum of the universe. Maybe not the perfect vacuum, but
Speaker 1: the most vacuuminess that the universe can get.
Speaker 2: Yeah, the vacuumiist. But I like that phrase maximum vacuum.
Speaker 2: That sounds cool like an eighties band starring Max headroom.
Speaker 1: Yeah with long long hair, Yeah, that might be out
Speaker 1: of our reach at our age.
Speaker 2: And to understand what's actually achievable, like how you can
Speaker 2: really relax space itself, you have to understand like how
Speaker 2: the fields wiggle and how they interact with each other,
Speaker 2: how energy slashes back and forth. It's sort of like
Speaker 2: you know when you lie down to take a nap
Speaker 2: and you feel like, okay, I'm totally relaxed. Then you discover,
Speaker 2: oh no, I'm actually holding this muscle tot and you
Speaker 2: learn to relax that, to relax that, and you only
Speaker 2: really ever fall asleep when all of your muscles are
Speaker 2: fully relaxed in their lowest energy state.
Speaker 1: Well, I guess maybe a question is there are fields
Speaker 1: that have zero energy to them or not? Or do
Speaker 1: all quantum fields have some inherent energy to them?
Speaker 2: No quantum fields can have zero energy in them. It's
Speaker 2: just an inherent property of any quantum object that cannot
Speaker 2: have zero energy.
Speaker 1: Why not.
Speaker 2: There's the mathematical approach, which is like you look at
Speaker 2: the shorter your equation, you try to solve it. The
Speaker 2: minimum energy solution is not at zero. The intuitive way
Speaker 2: to think about it is the heisember concertainty principle. Right,
Speaker 2: If you accept that things have a minimum uncertainty to them,
Speaker 2: then having zero energy would perfectly define its momentum and
Speaker 2: its location. At the same time, you would know too
Speaker 2: much about it. So in order to maintain the fuzziness
Speaker 2: of the universe, these quantum fields have to be buzzing
Speaker 2: a little bit.
Speaker 1: WHOA that seems to get really philosophical.
Speaker 2: Every time you try to understand quantum mechanics intuitively, you
Speaker 2: got to reach for philosophy. That's really all we have.
Speaker 2: You know, quantum mechanics has the beautiful mathematics which gives
Speaker 2: you answers. But you want like intuitive understanding, then it's
Speaker 2: all philosophy.
Speaker 1: But what do you mean, Like you can't have uncertainty
Speaker 1: with a perfect vacuum? Like could you have a field
Speaker 1: that has zero average energy but it kind of like
Speaker 1: has a negative state of being. I don't know, I
Speaker 1: don't know what I'm talking about, But why can't you
Speaker 1: have fuzziness and a zero average.
Speaker 2: The value of the field is zero on average, but
Speaker 2: the energy is not zero the same way that like
Speaker 2: when a string vibrates on the guitar. If you took
Speaker 2: pictures of where the string was and you average it's location.
Speaker 2: Its average location is at the most relaxed state, or
Speaker 2: at a straight string. You took any point on that
Speaker 2: string and asks like, where is it on average? On average,
Speaker 2: it's at its relaxed state. It's at the middle point
Speaker 2: where the string is straight. But it's oscillating still, right,
Speaker 2: it's still moving. So these fields can have energy while
Speaker 2: their average value is still at zero.
Speaker 1: And so what would happen if a string had no energy.
Speaker 2: Well, a classical string can have no energy, right, And
Speaker 2: that means you know exactly its location and exactly it's momentum.
Speaker 2: It's zero momentum. But a quantum object can't do that.
Speaker 2: You can't know both of those things simultaneously about a
Speaker 2: quantum object. And it's not just that we can't know it.
Speaker 2: Then information does not exist, cannot exist. It's not Noah bowl,
Speaker 2: it's not determined.
Speaker 1: Which wouldn't be a quantum object.
Speaker 2: Oh yeah, sure, if you want to overthrow quantum mechanics,
Speaker 2: then yes, you can have objects with zero energy. So
Speaker 2: classical fields definitely can. But all evidence suggests that all
Speaker 2: the fields we know about other than gravity at least
Speaker 2: are quantum fields. They have quantum properties.
Speaker 1: Wait, are you saying gravity is a non quantum field.
Speaker 2: Well, our theory of gravity is a classical one, right,
Speaker 2: and suggests that space can have zero curvature to it
Speaker 2: and all sorts of stuff. We don't have a quantum
Speaker 2: theory of gravity, so yeah, we have an only classical
Speaker 2: understanding of gravity. We're not successfully quantized gravity. We don't
Speaker 2: even know if gravity is a field or if it's
Speaker 2: just like the curvature of space. So that's not something
Speaker 2: we understand at all. But all the fields that we
Speaker 2: have been able to probe and understand, electromagnetism and the
Speaker 2: weak force, a strong force, these are definitely all quantum
Speaker 2: fields and so they definitely cannot have zero energy. Same
Speaker 2: with the Higgs field, also definitely a quantum field.
Speaker 1: So wait, then, are you saying that if gravity is
Speaker 1: not a quantum field, then you can have a non
Speaker 1: quantum field.
Speaker 2: It's possible that gravity is a non quantum field. Yeah,
Speaker 2: we just don't really understand gravity. I remember that Einstein's
Speaker 2: theory of gravity was developed basically at the same time
Speaker 2: as quantum mechanics, and so he wrote it as a
Speaker 2: classical theory. It makes all sorts of assumptions about the universe.
Speaker 2: You know that you can have smooth, continuous paths that
Speaker 2: you can know precisely the velocity and location of objects,
Speaker 2: things that we don't think are true about the universe.
Speaker 2: He built those into his theory, and yet it works
Speaker 2: in every location where we can test it. So it's
Speaker 2: a deep question in modern physics, like how do we
Speaker 2: reconcile general relativity with quantum mechanics. But yeah, it's possible
Speaker 2: that gravity is a field that's a classical field that
Speaker 2: could relax down to zero.
Speaker 1: I'm just trying to dig into what you say. I
Speaker 1: mean when you say it's not possible, what you actually
Speaker 1: mean is like it's not allowed under or the quantum
Speaker 1: view of the universe, which may or may not be true.
Speaker 2: Yeah, that's true. It might be that the final unification
Speaker 2: and understanding of the bigger picture of physics involves an
Speaker 2: overthrowing of quantum mechanics rather than general relativity. Maybe generativity
Speaker 2: is right, and space is a classical backdrop in some way,
Speaker 2: but in our current understanding of space at least it
Speaker 2: contains these quantum fields which can't go down to zero.
Speaker 2: But yeah, that could be all wrong.
Speaker 1: Okay, Well, let's get back to our discussion vacuums. So
Speaker 1: you're saying that maybe what we can talk about is
Speaker 1: maximum vacuum of the universe, which is when these fields
Speaker 1: relax down to the lowest level. And you're saying that
Speaker 1: there's kind of different ways for these fields to relax,
Speaker 1: Like there's meditation, there's drinking chamma meal.
Speaker 2: Tea, meditation and medication exactly. Well, you know, this sort
Speaker 2: of story of the universe is relaxation. The universe is expanding,
Speaker 2: which means it's getting more elude, which means it's getting
Speaker 2: lower temperature. Right, it's cooling down. As the universe expands,
Speaker 2: the matter gets more and more sparse, and so the
Speaker 2: energy in those fields is going down, down, down, down down.
Speaker 2: So we think about the whole universe as relaxing. All
Speaker 2: the common fields are sort of chill and out heading
Speaker 2: towards zero.
Speaker 1: Wait, what does that mean? Does that mean like a
Speaker 1: field can have a lot of energy and it can
Speaker 1: have a little bit of energy.
Speaker 2: Yeah, fields in the center of the sun have a
Speaker 2: lot of energy. Fields out in intergalactic space have much
Speaker 2: less energy.
Speaker 1: No, But I mean, like as a concept of a field, right, like.
Speaker 2: Well, having multiple particles just means that field is wiggling
Speaker 2: more like the field wiggles, that's one particle. The field
Speaker 2: wiggles more, that's two particles. Field wiggles even more, that's
Speaker 2: a billion particles.
Speaker 1: I guess I was referring to this idea that maybe
Speaker 1: there's a chunk in space out there with nothing in
Speaker 1: it that has fields in it that are vibrating and
Speaker 1: have energy to it. Can that energy be different values?
Speaker 2: So it depends on how space cools, right, It's sort
Speaker 2: of like making a sou fle. You've got to get
Speaker 2: it to that special configuration. So the universe is cooling,
Speaker 2: time is going on, space is relaxing, And then I
Speaker 2: think the question you're asking is like, could it relax
Speaker 2: into different values? Could you have like one state of
Speaker 2: energy over here, another state of lower energy over there?
Speaker 1: Yeah, Like can the electron feel when it relaxes down
Speaker 1: to its minimum? Can it relax down to point one
Speaker 1: or point three or point four or when it relaxes
Speaker 1: there's just one possible relaxation met.
Speaker 2: So almost all the fields relax in a very simple way,
Speaker 2: which is heading towards zero and hitting that minimum, so
Speaker 2: that their average value is zero and they have the
Speaker 2: minimum energy, and that should be the same everywhere in
Speaker 2: the universe. But one field, the Higgs field, has some
Speaker 2: weird wiggles in it and it gets stuck as it cools.
Speaker 2: So the whole universe is cooling down. Everything is settling down,
Speaker 2: sort of rolling towards the bottom of a valley, but
Speaker 2: the Higgs field gets stuck in this false vacuum. Is
Speaker 2: a large amount of energy stuck in it high potential
Speaker 2: energy configuration. While everything else like rolled to the bottom
Speaker 2: of a canyon. It got stuck sort of like on
Speaker 2: a shelf on the canyon wall. So the Higgs field
Speaker 2: is different from all the other fields. It's harder for
Speaker 2: it to relax because the shape of its potential energy.
Speaker 1: I think what you mean is like like if each
Speaker 1: field is like the string and a guitar. All of
Speaker 1: the fields kind of settled down to kind of a
Speaker 1: minimum vibration, but the Higgs field is kind of stuck
Speaker 1: in this kind of high vibration state.
Speaker 2: It's not actually vibrating, and it has high potential energy.
Speaker 2: So while everything else settled down to like the lowest
Speaker 2: possible vibration, it got like stuck in this configuration where
Speaker 2: somebody's pulling it really hard, and it's taught, it's not vibrating,
Speaker 2: there's not a lot of kinetic energy, has a lot
Speaker 2: of potential energy. So the Higgs field sort of like
Speaker 2: got stuck on a bump on the side of your
Speaker 2: guitar and it's pulled sideways and taught and stuck there.
Speaker 1: Like there's a certain curve to the string. Maybe I
Speaker 1: don't know, And so.
Speaker 2: One question is like, is that the true vacuum or
Speaker 2: is that a false vacuum. Is it possible for the
Speaker 2: Higgs field to relax to a lower state, And we've
Speaker 2: talked about that several times, like if the Higgs field
Speaker 2: would collac to a lower potential energy configuration, that would
Speaker 2: change the nature of physics in our universe, and you know,
Speaker 2: all of our atoms would explode at the speed of
Speaker 2: light and all sorts of crazy stuff. But we think
Speaker 2: that probably there are multiple possible vacuum states, and the
Speaker 2: Higgs field is stuck in sort of a false vacuum,
Speaker 2: and the true vacuum is a lower energy configuration that
Speaker 2: it can't quite get to. It's sort of stuck in this.
Speaker 1: Vacuum m like the Higgs field can relax to maybe lower,
Speaker 1: but for some reason it's not.
Speaker 2: Yeah, somebody's holding on to that string.
Speaker 1: It's the finger of God or the God's pick.
Speaker 2: Maybe God's just in a dad band and that defines
Speaker 2: the nature of the universe.
Speaker 1: Yeah, there you go. That's right. And his dad is.
Speaker 2: Called maximum vacuum.
Speaker 1: Maximum vacuum. That's right. Now, does God play all the
Speaker 1: instruments or is he like a one man dad. It's
Speaker 1: like the Holy Quick quintet, you know.
Speaker 2: But then all members are actually part of the one.
Speaker 2: I don't have enough theological background to comment on that
Speaker 2: without offending.
Speaker 1: People anyways, So you were saying that maybe like we're
Speaker 1: not in the most vacuumus of vacuums that the universe
Speaker 1: can be in, and thankfully.
Speaker 2: All space out there probably has some particles in it.
Speaker 2: Even if you were able to remove particles from space,
Speaker 2: you would have space in this sort of Higgs field
Speaker 2: that's stuck at a high potential energy. And so yeah,
Speaker 2: probably nothing out there currently is even capable of getting
Speaker 2: to the maximum vacuum state that our kind of space
Speaker 2: is technically capable of achieving.
Speaker 1: And thankfully right, because if we ever flip to that
Speaker 1: lower or more vacuum e vacuum, then we're all toast
Speaker 1: like our universe would kind of get upturned and really suck.
Speaker 2: Absolutely. We have a whole episode about what would happen
Speaker 2: if the Higgs field did go to zero, and yeah,
Speaker 2: it would ruin your life.
Speaker 1: On the plus that you wouldn't have to vacuum your
Speaker 1: house anymore.
Speaker 2: It would be automatically vacuumed.
Speaker 1: Just room ba our way to a more blissful existence.
Speaker 1: All right, Well, I think the answer to our question
Speaker 1: of the episode is that a vacuum, it would be
Speaker 1: a spot with nothing in it, not even energy. And
Speaker 1: as far as we know, our universe kind of has
Speaker 1: something in it everywhere, and so a perfect vacuum it's
Speaker 1: not possible, and we have to settle for the eighties
Speaker 1: Coverman maximum vacuum.
Speaker 2: And when physicists talk about vacuums, that's what they mean.
Speaker 2: They mean a chunk of space with no particles in it,
Speaker 2: relaxed to its maximum possible state, which is not zero energy.
Speaker 1: I feel like physicists are settling then, though. Can't they
Speaker 1: be striving for perfection?
Speaker 2: No, we're just defining our achievements as success.
Speaker 1: I see, you're lowering your standards.
Speaker 2: We're redefining success. Everyone gets a trophy exactly, participation vacuum.
Speaker 1: All right, well, I guess the next time you look
Speaker 1: at into the that's of space, think about the idea
Speaker 1: that there is nothing out there that is truly nothing.
Speaker 1: There's always something out there in the universe.
Speaker 2: Nothingness has a lot of something to think.
Speaker 1: About that's not nothing. Well, we hope you enjoyed that.
Speaker 1: Thanks for joining us, see you next time.
Speaker 2: Thanks for listening, and remember that Daniel and Jorge explain
Speaker 2: the Universe is a production of iHeartRadio. For more podcasts
Speaker 2: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever
Speaker 2: you listen to your favorite shows.