Latest / Daniel and Kelly’s Extraordinary Universe / Does quantum mechanics conserve energy?

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Does quantum mechanics conserve energy? · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, Jorge, are you worried about energy conservation?
• 0:12
  Speaker 2: Uh?
• 0:13
  Speaker 3: Not worried, but I try to do as much of
• 0:15
  Speaker 3: it as possible.
• 0:16
  Speaker 4: Oh.
• 0:16
  Speaker 1: Is that because you're very environmentally responsible?
• 0:19
  Speaker 3: Nuts? Because I try to do this little exercise as possible.
• 0:23
  Speaker 1: You're such an adult.
• 0:25
  Speaker 3: Hey, I'm doing it for the planet, not just for me.
• 0:28
  Speaker 1: Well on behalf of planet Earth. We're all very grateful
• 0:30
  Speaker 1: for your lazy attitude.
• 0:32
  Speaker 3: Oh thanks. My body is also very grateful, although maybe
• 0:36
  Speaker 3: not in the long term. Hi am Jorgem, a cartoonist
• 0:53
  Speaker 3: and the author of Oliver's Great Big Universe.
• 0:56
  Speaker 1: Hi. I'm Daniel. I'm a high energy particle physicist, but
• 1:00
  Speaker 1: I don't often feel very high energy or high. There
• 1:06
  Speaker 1: were times in my life when that was more true.
• 1:07
  Speaker 3: Than Yeah, I seem to remember those times. Yeah. But
• 1:12
  Speaker 3: isn't it high a relative term at least in physics?
• 1:15
  Speaker 3: Like how high is high energy? Can't you always go
• 1:17
  Speaker 3: higher in energy?
• 1:18
  Speaker 1: You can always go higher in energy? And what people
• 1:21
  Speaker 1: called high energy fifty years ago we now call nuclear physics.
• 1:25
  Speaker 1: So it doesn't even qualify what it's not low energy,
• 1:29
  Speaker 1: It doesn't even qualify as low energy physics.
• 1:32
  Speaker 3: I guess nobody wants to be called a low energy physicist.
• 1:36
  Speaker 1: Yeah, would you want to be called a low energy cartoonist?
• 1:40
  Speaker 3: Well, I am, and if you call me that it
• 1:43
  Speaker 3: would be accurate. But I guess you can call me that,
• 1:47
  Speaker 3: why not?
• 1:47
  Speaker 1: Yeah? Sure? Well, high energy really means highest energy. And
• 1:51
  Speaker 1: as we keep pushing the boundaries of what we can achieve,
• 1:55
  Speaker 1: then yesterday's high energy collider is today's nuclear physics.
• 1:59
  Speaker 3: Mm sounds like a good slogan for the LGC. Yesterday's
• 2:02
  Speaker 3: high energies now today's nuclear energy. But anyways, welcome to
• 2:05
  Speaker 3: our podcast Daniel and Jorge Explain the Universe, a production
• 2:09
  Speaker 3: of iHeartRadio.
• 2:10
  Speaker 1: In which we use all of our energy to help
• 2:12
  Speaker 1: you understand the nature of the universe. We tear things apart,
• 2:17
  Speaker 1: we peer inside. We try to understand at a microscopic level,
• 2:20
  Speaker 1: how does everything work? Is there a story we can
• 2:23
  Speaker 1: tell about what's happening to the littlest bits in the
• 2:27
  Speaker 1: universe and how it comes together to explain our reality?
• 2:30
  Speaker 3: That's right. We like to explore the high energies, the
• 2:33
  Speaker 3: low energies, and all the energies in between that there
• 2:35
  Speaker 3: are in this universe to discover, to explore, to learn about,
• 2:38
  Speaker 3: and to blow your mind with.
• 2:40
  Speaker 1: And energy is a really central concept in physics and
• 2:43
  Speaker 1: in people's understanding of physics. We'd like to think about
• 2:47
  Speaker 1: things in terms of energy, little quantum fields vibrating with energy,
• 2:51
  Speaker 1: energy being passed between particles, energy used to create particles.
• 2:55
  Speaker 1: In some sense, physics is a study.
• 2:58
  Speaker 3: Of energy, and one that requires some amount of energy
• 3:00
  Speaker 3: to explore, right, I mean, you can't just do physics
• 3:03
  Speaker 3: from your couch.
• 3:04
  Speaker 5: Can you.
• 3:06
  Speaker 1: I don't know if it takes more energy to do
• 3:07
  Speaker 1: physics or cartooning, but you can sort of lie in
• 3:10
  Speaker 1: your couch and just think about the universe, you know,
• 3:13
  Speaker 1: the way the great theorists and the Greeks have done.
• 3:15
  Speaker 1: But absolutely to do experiments to explore the universe, to
• 3:20
  Speaker 1: investigate it deeply, you need to poke it, you need
• 3:22
  Speaker 1: to probe it, you need to interact with it, and
• 3:24
  Speaker 1: that does take some energy.
• 3:27
  Speaker 3: Well, I feel like energy is kind of a topic,
• 3:29
  Speaker 3: that it's a word you learn as a kid, and
• 3:31
  Speaker 3: that everybody has heard of this word and we all
• 3:34
  Speaker 3: use it every day in our everyday lies. But to
• 3:36
  Speaker 3: actually define energy is kind of tricky, isn't it, Not
• 3:40
  Speaker 3: just from a physics point of view, but also if
• 3:42
  Speaker 3: you ask somebody what energy is, You don't get an
• 3:45
  Speaker 3: easy answer.
• 3:46
  Speaker 1: Yeah, energy is a very loaded term, right. We have
• 3:48
  Speaker 1: a sense of like feeling like you have low energy
• 3:51
  Speaker 1: in the morning, or running out of energy to do
• 3:54
  Speaker 1: some chores or something. But it's one of these words
• 3:56
  Speaker 1: that physics has redefined to have a specific meaning, a
• 4:00
  Speaker 1: very crisp idea for what energy means. The way we
• 4:03
  Speaker 1: also have like meanings for force and work and other
• 4:06
  Speaker 1: words that we also use in everyday English without as
• 4:09
  Speaker 1: precise definitions.
• 4:11
  Speaker 3: Right, But even those the simple terms have been changing
• 4:13
  Speaker 3: in physics over time, right, Like the word the idea
• 4:15
  Speaker 3: for force has changed with quantum mechanics. Isn't it Like
• 4:19
  Speaker 3: it used to be an invisible force that we feel
• 4:21
  Speaker 3: towards the Earth or the sun, But now they're talking
• 4:23
  Speaker 3: that maybe it's like a particle or something, it's an
• 4:26
  Speaker 3: exchange of particles.
• 4:27
  Speaker 1: Yeah, the mechanism that explains it is definitely different. I
• 4:30
  Speaker 1: think the concept of force is a change in momentum
• 4:33
  Speaker 1: of something. Something in exchange of momentum essentially has been
• 4:36
  Speaker 1: pretty constant since Newton. Yeah, these things definitely can change.
• 4:40
  Speaker 1: And you know, for example, we've redefined gravity to not
• 4:43
  Speaker 1: even be a force, So what gets counted as a
• 4:45
  Speaker 1: force and what doesn't and how that all works definitely changes.
• 4:49
  Speaker 1: And we like to dig into these basic principles and say, like,
• 4:51
  Speaker 1: what does this really mean? Where does it come from?
• 4:53
  Speaker 1: Did the universe have to me this way? Is energy
• 4:56
  Speaker 1: essential to the universe? And one of the ways that
• 4:58
  Speaker 1: we do that is by noticing what the universe respects,
• 5:01
  Speaker 1: like what doesn't change in the universe, what's constant, what's conserved.
• 5:05
  Speaker 1: That gives you a clue about sort of what's important
• 5:08
  Speaker 1: to the underlying machinery of the universe.
• 5:11
  Speaker 3: Right, you kind of want to know what the rules
• 5:12
  Speaker 3: of the universe are, or what the principles of the
• 5:14
  Speaker 3: universe are by which it lets things happen in it,
• 5:19
  Speaker 3: right exactly.
• 5:20
  Speaker 1: And one of the deepest rules that people imagine in
• 5:23
  Speaker 1: the universe follows is conservation of energy. That energy is
• 5:28
  Speaker 1: somehow immutable, that it can slosh between different kinds of
• 5:31
  Speaker 1: energy kinetic to potential, to mass, to velocity to whatever.
• 5:35
  Speaker 1: But the energy has to go somewhere and has to
• 5:37
  Speaker 1: come from somewhere. That it's a basic component of the
• 5:41
  Speaker 1: universe itself.
• 5:43
  Speaker 3: Yeah, it's a very fundamental rule that people seem to
• 5:46
  Speaker 3: learn about even in high school physics. But is it
• 5:49
  Speaker 3: actually true? Does it always happen in this universe or
• 5:52
  Speaker 3: does it get broken at some levels, like the quantum levels.
• 5:57
  Speaker 3: And so to the end the podcast, we'll be asking
• 5:59
  Speaker 3: the question does quantum mechanics conserve energy? Now, when you
• 6:09
  Speaker 3: say quantum mechanics, do you mean like the field or
• 6:13
  Speaker 3: the people who study quantum mechanics.
• 6:16
  Speaker 1: The mechanics of quantum physics.
• 6:18
  Speaker 3: Can you be a quantum mechanic like a car mechanic,
• 6:22
  Speaker 3: but at the quantum level.
• 6:23
  Speaker 1: Yeah, bring your fields in. They need some new parts.
• 6:25
  Speaker 1: We'll order them.
• 6:26
  Speaker 3: That's right, Your quantum carburetor needs to be swapped out, exactly.
• 6:31
  Speaker 1: No, in this case, we're talking about the rules of
• 6:34
  Speaker 1: the smallest bits in the universe, the tiniest little things,
• 6:37
  Speaker 1: the electrons, the positrons of photons, all the smallest stuff
• 6:40
  Speaker 1: in the universe seems to operate on different rules than
• 6:44
  Speaker 1: the bigger stuff in the universe baseballs and basketballs and
• 6:47
  Speaker 1: rocks and stuff that we're familiar with. And so while
• 6:49
  Speaker 1: we're taught that energy is concerned very generally, we're interested
• 6:53
  Speaker 1: in whether that's always true, and whether it's true at
• 6:56
  Speaker 1: the smallest scale.
• 6:57
  Speaker 3: Yeah, so this is a big question. Does quantum mechanics
• 7:00
  Speaker 3: conserve energy? And so, as usually, we were wondering how
• 7:03
  Speaker 3: many people out there had thought about this question, whether
• 7:05
  Speaker 3: this is a rule that can be broken at the
• 7:07
  Speaker 3: quantum level, or whether the whole universe follows it.
• 7:10
  Speaker 1: Thanks very much to everybody who answers these questions. If
• 7:13
  Speaker 1: you would like to receive a regular dose of tough
• 7:16
  Speaker 1: physics questions in your inbox, right to me too, questions
• 7:20
  Speaker 1: at Danielandhorge dot com, and I will send them to you.
• 7:23
  Speaker 3: Well, regular dose. Now do these doses make you high
• 7:27
  Speaker 3: in physics?
• 7:29
  Speaker 1: These are microdoses, so yeah.
• 7:30
  Speaker 3: Oh, I see right, it's more of a low key high.
• 7:34
  Speaker 1: They're not supposed to blow your mind. They're just supposed
• 7:36
  Speaker 1: to color your experience of the universe a little bit.
• 7:39
  Speaker 3: I see. It's more of a nuclear.
• 7:41
  Speaker 1: Hit exactly, It's not a high energy dose.
• 7:46
  Speaker 3: Well, think about it for a second. Do you think
• 7:48
  Speaker 3: quantum mechanics conserves energy? Here's what people have to say.
• 7:53
  Speaker 5: I think so, or at least the rate of decay
• 7:56
  Speaker 5: is so minute that we are not currently able to
• 8:02
  Speaker 5: detect it on a cosmological scale.
• 8:06
  Speaker 6: I think quantum mechanics conserves energy. I feel like it
• 8:09
  Speaker 6: would be big news if we found the law of
• 8:10
  Speaker 6: conservation of energies to be violated, though maybe it has
• 8:14
  Speaker 6: been and I just haven't seen that news. But the
• 8:16
  Speaker 6: notion of quantum fluctuations seems like it would violate that law.
• 8:20
  Speaker 6: Though I don't really understand quantum fluctuations.
• 8:22
  Speaker 2: I'm assuming it doesn't just because I remember listening to
• 8:25
  Speaker 2: your podcast on how energy actually isn't conserved in the universe.
• 8:29
  Speaker 2: So I'm assuming that quantum mechanics follows that as well,
• 8:32
  Speaker 2: But I don't actually know.
• 8:33
  Speaker 4: I'm not sure about this question. And like conserve in
• 8:38
  Speaker 4: what like in your book frequently asked questions about the universe,
• 8:43
  Speaker 4: you did say like there was like a quantum foam,
• 8:47
  Speaker 4: and like when the universe is expanding, it's just connecting
• 8:50
  Speaker 4: to more quantum particles, I guess. So I'm going to say,
• 8:58
  Speaker 4: I don't know, because if you mean in the universe,
• 9:02
  Speaker 4: like not the growing section, then no. But if we
• 9:07
  Speaker 4: even include all the other disconnected quantum phone then I'm
• 9:11
  Speaker 4: not sure.
• 9:13
  Speaker 3: All right. People are on the fence about this. Some
• 9:14
  Speaker 3: people say it does, some people say they don't think so. Well,
• 9:18
  Speaker 3: they're not sure.
• 9:19
  Speaker 1: Yeah, I was really surprised by this. I was expecting
• 9:22
  Speaker 1: people to rush to the defense of conservation of energy
• 9:24
  Speaker 1: and say it's a fundamental law of the universe.
• 9:27
  Speaker 3: Maybe it's because we've had whole episodes where we say
• 9:30
  Speaker 3: that the energy is not conserving the universe that maybe
• 9:34
  Speaker 3: influence the answers here.
• 9:36
  Speaker 1: Oh my gosh, people actually listening and absorbing the content.
• 9:40
  Speaker 3: Amazing, amazing, they're learning. Well, it's great that they are
• 9:43
  Speaker 3: listening to us. And because we have talked about this
• 9:46
  Speaker 3: idea of conservation of energy in the universe, and we've
• 9:49
  Speaker 3: talked about how it's not actually conserved in the universe
• 9:51
  Speaker 3: as a whole.
• 9:52
  Speaker 1: Right, that's right, And that was in the context of
• 9:54
  Speaker 1: sort of general relativity, thinking about the universe as it
• 9:57
  Speaker 1: expands and as space is changing, how we define energy
• 10:02
  Speaker 1: in that context, and that sort of blows a lot
• 10:04
  Speaker 1: of people's minds to understand that energy might not be
• 10:07
  Speaker 1: conserved in the universe at the biggest scales, you know,
• 10:10
  Speaker 1: when you zoom all the way out and think about
• 10:12
  Speaker 1: how the universe is expanding and what happens to stuff
• 10:15
  Speaker 1: inside of it.
• 10:16
  Speaker 3: Right, Because in the other episode we talked about how
• 10:18
  Speaker 3: the universe is expanding due to dark energy, and basically
• 10:22
  Speaker 3: like there's more space being created all the time out
• 10:25
  Speaker 3: of nothing, which means that energy sort of being added
• 10:28
  Speaker 3: to the universe, created in the universe out of nothing.
• 10:31
  Speaker 1: Right, Yeah, that's right, and you're coming out of nothing,
• 10:33
  Speaker 1: I think says a lot. You know, it implies that
• 10:35
  Speaker 1: energy needs to come from somewhere, and so when you
• 10:38
  Speaker 1: say energy is created, you have to give some explanation
• 10:40
  Speaker 1: for where it comes from, even if you're saying out
• 10:43
  Speaker 1: of nothing. But this tells us that energy isn't something
• 10:46
  Speaker 1: fundamental to the universe. That it can go up and
• 10:48
  Speaker 1: it can go down, like lots of things in the universe,
• 10:51
  Speaker 1: like the number of people in swimming pools is not
• 10:53
  Speaker 1: a constant number of the universe. It can go up
• 10:55
  Speaker 1: and it can go down.
• 10:56
  Speaker 3: How do you know? Are you sure the.
• 11:00
  Speaker 1: Middle of an extensive worldwide experiment to measure the number
• 11:03
  Speaker 1: of people.
• 11:04
  Speaker 3: At any moment? Yes, Oh, you thought you were going to.
• 11:07
  Speaker 1: Challenge me on that and call me out, But actually
• 11:09
  Speaker 1: I've been doing this in preparation for five years just
• 11:11
  Speaker 1: to make that casual comment.
• 11:13
  Speaker 3: You know, somehow I don't believe you any.
• 11:16
  Speaker 1: Away from my paper in nature. Okay, it's coming out soon,
• 11:19
  Speaker 1: I promise.
• 11:20
  Speaker 3: Sure. Let's see the draft. Read me a poll paragraph
• 11:23
  Speaker 3: from the draft right now.
• 11:25
  Speaker 1: Oh, I can't disembargo it because it's too high profile.
• 11:29
  Speaker 3: I see.
• 11:30
  Speaker 1: I signed an NBA. What am I gonna do? No,
• 11:32
  Speaker 1: obviously I have not done that experiment.
• 11:34
  Speaker 3: A nuclear disclosure agreement, which means it's really low.
• 11:38
  Speaker 1: But clearly there are things in the universe that do change,
• 11:42
  Speaker 1: things that are not fundamental to the universe, while there
• 11:44
  Speaker 1: are other things that are fundamental, like momentum. We think
• 11:47
  Speaker 1: momentum is conserved in the universe, and that comes from
• 11:50
  Speaker 1: a really deep symmetry about space and time that the
• 11:54
  Speaker 1: experiments you do anywhere in the universe should give you
• 11:56
  Speaker 1: the same answer. That doesn't matter where you put your
• 11:58
  Speaker 1: origin in space. Rules of physics don't care, and that
• 12:02
  Speaker 1: gives you directly as a consequence of Nuther's theorem, momentum conservation.
• 12:07
  Speaker 1: But energy is not in that same category, and energy
• 12:10
  Speaker 1: can go down and it can go up, like when
• 12:12
  Speaker 1: the universe expands, you get in new space, and that
• 12:14
  Speaker 1: space comes with energy, but also energy gets decreased because
• 12:17
  Speaker 1: as space expands, it reddens the wavelengths of all the
• 12:20
  Speaker 1: photons inside of it. Take for example, the cosmic microwave
• 12:23
  Speaker 1: background radiation from the early universe. When it was created,
• 12:27
  Speaker 1: it was very high energy. That plasma was super dup
• 12:30
  Speaker 1: or hot. It was thousands of degrees kelvin. But it's
• 12:32
  Speaker 1: been stretched out by the expansion of the universe to
• 12:35
  Speaker 1: very long wavelengths, and now it's at like three degrees kelvin.
• 12:39
  Speaker 1: Where do that energy go? Didn't go anywhere, it's just gone.
• 12:42
  Speaker 3: Well, it's not gone, it's just gonna spread out, is it.
• 12:44
  Speaker 1: No, there's less energy in those photons. Those photons have
• 12:47
  Speaker 1: gone from high energy to low.
• 12:49
  Speaker 3: Energy because they got stretched out.
• 12:51
  Speaker 1: But the total energy is also different. It's not just
• 12:54
  Speaker 1: the energy density.
• 12:55
  Speaker 3: But they're longer now, that's what those are longer. Yeah,
• 12:59
  Speaker 3: isn't where the energy went.
• 13:01
  Speaker 1: The energy of those photons is less. They're also longer,
• 13:04
  Speaker 1: but the energy of those photons is less. If you
• 13:06
  Speaker 1: stretch space, the photons get redder, which means they have
• 13:08
  Speaker 1: less energy.
• 13:09
  Speaker 3: Well, I guess this is what I mean. Because the
• 13:11
  Speaker 3: idea of energy, the concept of energy can really vary
• 13:15
  Speaker 3: into a lot of these arguments about whether it can
• 13:17
  Speaker 3: can be conserved or not. I feel like maybe they
• 13:19
  Speaker 3: depend on a good definition of energy, and so maybe
• 13:22
  Speaker 3: for folks we should talk about what energy actually is,
• 13:25
  Speaker 3: how to physicists define it.
• 13:26
  Speaker 1: Yeah, I wish I knew what energy was.
• 13:29
  Speaker 3: Wait, what.
• 13:32
  Speaker 1: Energy is a really slippery topic. It's something we've been
• 13:34
  Speaker 1: struggling with over the last few decades to really define.
• 13:38
  Speaker 1: We have some very crisp but unsatisfying definitions of energy.
• 13:41
  Speaker 1: You know, in some cases you can say energy is
• 13:44
  Speaker 1: the thing that's conserved over time, you know, so you
• 13:47
  Speaker 1: can define it to be something that's conserved. Really, I
• 13:50
  Speaker 1: think a better way to define energy is to talk
• 13:51
  Speaker 1: about like the forms it can take. You know, like
• 13:54
  Speaker 1: there's kinetic energy, which means energy of motion. Something is
• 13:57
  Speaker 1: moving that has energy. There's potential energy, this energy of configuration.
• 14:01
  Speaker 1: Like a book is sitting on the shelf, there's energy
• 14:04
  Speaker 1: stored in that. You know, it takes energy to put
• 14:06
  Speaker 1: the book on the shelf. Mass, for example, is a
• 14:09
  Speaker 1: representation of internal stored energy. Put a bunch of photons
• 14:13
  Speaker 1: into a box, they have energy. That box now has
• 14:16
  Speaker 1: more mass. All these are different ways you can calculate energy,
• 14:19
  Speaker 1: and if you add them all up, you get the
• 14:21
  Speaker 1: total energy. And so that's sort of how we define energy,
• 14:24
  Speaker 1: but you know it's a little hand wavy.
• 14:26
  Speaker 3: Wait wait, wait, So I was right earlier when I
• 14:28
  Speaker 3: said that I don't really know what energy kind of is,
• 14:30
  Speaker 3: but you made it seem like we did know.
• 14:32
  Speaker 1: We don't really know what energy is in the broadest sense,
• 14:34
  Speaker 1: but we can define something and say this is what
• 14:37
  Speaker 1: we call energy. I don't know if it really captures
• 14:39
  Speaker 1: our full experience of energy, but yeah, we can write
• 14:42
  Speaker 1: down a formula for what energy is.
• 14:45
  Speaker 3: But I guess the question is what did those things
• 14:47
  Speaker 3: have in common? And why do you use the same
• 14:49
  Speaker 3: word for all of them? The kinetic energy, potential energy,
• 14:53
  Speaker 3: you know, energy of mass. Why do you use the
• 14:55
  Speaker 3: same word for all of those things?
• 14:57
  Speaker 1: Yeah, great question, And the reason is that in classical
• 14:59
  Speaker 1: mechare at least, you know, things moving around at our
• 15:02
  Speaker 1: scale at or fairly low speeds. We notice that they
• 15:05
  Speaker 1: can turn back and forth into each other. Like you
• 15:07
  Speaker 1: take that book on the shelf. It has potential energy
• 15:09
  Speaker 1: and no kinetic energy. You push it off the shelf.
• 15:11
  Speaker 1: Now it's speeding up towards the ground. It's losing potential
• 15:14
  Speaker 1: energy and gaining kinetic energy. So we notice that these
• 15:17
  Speaker 1: things can turn into each other, and therefore we group
• 15:20
  Speaker 1: them together into one big category. And we notice that,
• 15:23
  Speaker 1: at least in classical mechanics, the total the sum of
• 15:26
  Speaker 1: them all does stay constant. So like if you're add
• 15:29
  Speaker 1: of all the potential energy and all the kinetic energy
• 15:31
  Speaker 1: at one moment, and you do it again later, you
• 15:33
  Speaker 1: find you get the same answer.
• 15:36
  Speaker 3: And how does that relate to the energy of a
• 15:38
  Speaker 3: photocon which you mentioned earlier.
• 15:40
  Speaker 1: So now we're departing classical mechanics a little bit. We're
• 15:42
  Speaker 1: talking about a quantum object, but we can still think
• 15:45
  Speaker 1: about the energy of a photon. A photon has kinetic
• 15:48
  Speaker 1: energy because it's in motion, it's always in motion. It
• 15:51
  Speaker 1: has only kinetic energy. So photons definitely have energy.
• 15:55
  Speaker 3: Well, it seems like maybe the common factor is the
• 15:57
  Speaker 3: idea of motion, like things moving have energy to them,
• 16:01
  Speaker 3: and things that can move in the future or can
• 16:04
  Speaker 3: cost things to move, or like the potential to cost
• 16:06
  Speaker 3: something to move, is what maybe you would call energy.
• 16:09
  Speaker 1: Maybe I think that puts kinetic energy in a more
• 16:11
  Speaker 1: primary position than potential energy, which I'm not sure is justified.
• 16:15
  Speaker 1: I think there really are at its core two different
• 16:18
  Speaker 1: kinds of energy. There stored energy potential energy and kinetic energy.
• 16:21
  Speaker 1: I'm not sure which one would be more fundamental.
• 16:24
  Speaker 3: And so are those the only two kinds of energy?
• 16:26
  Speaker 3: So you have in classical physics kinetic and potential.
• 16:30
  Speaker 1: Yeah, those are the two forms. People might think, what
• 16:32
  Speaker 1: about mass? What is mass? Is that kinetic energy or
• 16:35
  Speaker 1: potential energy? It's sort of a special case. It's just
• 16:37
  Speaker 1: sort of a label we give some kinds of energy
• 16:40
  Speaker 1: if they're stored internally, Like if you have gluons inside
• 16:44
  Speaker 1: of proton, they have a bunch of kinetic energy they're
• 16:47
  Speaker 1: zooming around. They also have potential energy of their bonds.
• 16:49
  Speaker 1: All that energy is inside the proton, so we call
• 16:52
  Speaker 1: that mass. So mass is sort of a label we
• 16:54
  Speaker 1: give to some energy, but it's not on the same
• 16:57
  Speaker 1: level as like kinetic and potential it's not its own
• 16:59
  Speaker 1: kind of energy.
• 17:01
  Speaker 3: So then if an eight year old asked you, hey,
• 17:04
  Speaker 3: doctor Whitson, what is energy? What would you answer?
• 17:07
  Speaker 1: I would say, I've had this nightmare scenario many times
• 17:10
  Speaker 1: and I have no idea how to respond.
• 17:12
  Speaker 3: You would spring in their face, Ah, run away, No, seriously, like,
• 17:18
  Speaker 3: what would you say, you have to say something? What
• 17:21
  Speaker 3: would you say, I'll get you started. It's a quantity that.
• 17:27
  Speaker 1: I'd say, energy is something that makes things move, but
• 17:29
  Speaker 1: it's also something you can store. That's my best shot.
• 17:34
  Speaker 3: It's almost like a liquid or something.
• 17:36
  Speaker 1: You know, for a long time people did imagine that
• 17:38
  Speaker 1: energy in the form of heat was a liquid that
• 17:40
  Speaker 1: flowed between things. But it's not a physical quantity in itself.
• 17:45
  Speaker 1: It's a description of the physical state of other quantities.
• 17:48
  Speaker 1: Like a liquid can have energy, but so can solids.
• 17:51
  Speaker 1: It's not like when energy flows from one thing to another,
• 17:54
  Speaker 1: there's some physical substance that moves between it. It changes
• 17:58
  Speaker 1: the state of those objects.
• 18:00
  Speaker 3: Well, I guess I'm a little surprised you're having so
• 18:02
  Speaker 3: much trouble just defining energy, which is pretty interesting. But
• 18:06
  Speaker 3: as you said, I think one thing that we do
• 18:08
  Speaker 3: sort of know about it is that in some cases
• 18:09
  Speaker 3: it's conserved and maybe in some cases it's not.
• 18:13
  Speaker 1: So.
• 18:13
  Speaker 3: Well, let's dig into the question and when it's conserved,
• 18:15
  Speaker 3: is it conserved at the quantum level or is it not.
• 18:19
  Speaker 3: So let's dig into that, But first let's take a
• 18:21
  Speaker 3: quick break. All right, we are mustering up the energy
• 18:37
  Speaker 3: to talk about something that apparently physicists can't define energy,
• 18:41
  Speaker 3: such a basic word that even little kids use, everyone
• 18:45
  Speaker 3: uses their in their daily lives. But it seems Daniel,
• 18:49
  Speaker 3: that it's something physicists can't really define very well. Maybe
• 18:53
  Speaker 3: only mathematically you can define it. Is that kind of
• 18:55
  Speaker 3: the case.
• 18:56
  Speaker 1: Yeah, And as you'll see, when we get into the
• 18:58
  Speaker 1: quantum system, this is going to be even trickier. And
• 19:01
  Speaker 1: physicists disagree about how to define energy and whether we
• 19:05
  Speaker 1: can even define it in terms of quantum systems.
• 19:08
  Speaker 3: Well, it seems like we don't even need to get
• 19:09
  Speaker 3: through you already don't know how to define it exactly.
• 19:12
  Speaker 1: And that's why I want to be upfront about how
• 19:15
  Speaker 1: complicated and confusing this topic is, even in the easy case,
• 19:18
  Speaker 1: because when we get to the hard case, it's going
• 19:21
  Speaker 1: to get even trickier. So I did my best to
• 19:23
  Speaker 1: give you like my understanding of energy, but if you
• 19:25
  Speaker 1: look at the official definition of energy, I find it's
• 19:27
  Speaker 1: even less satisfying. Like if you just google energy and
• 19:31
  Speaker 1: you ask Wikipedia or chat GPT, like, what is energy?
• 19:34
  Speaker 3: Well, it's you know, legit sources.
• 19:36
  Speaker 1: Legit sources. They say energy is the quantitative property that
• 19:40
  Speaker 1: is transferred to a body, and that doesn't really even
• 19:42
  Speaker 1: tell you what it is. It's like Okay, well, it
• 19:44
  Speaker 1: can move from one thing to another, but what is it? Man,
• 19:47
  Speaker 1: it doesn't really answer that question.
• 19:50
  Speaker 3: Well, that's kind of what I meant before, is that
• 19:51
  Speaker 3: it's a quantity. Is basically kind of the only way
• 19:55
  Speaker 3: you physicists know how to define it, right, it's a
• 19:57
  Speaker 3: it's a quantity. It's something that can measure, that can
• 20:01
  Speaker 3: be a lot or a little, which you seem to
• 20:04
  Speaker 3: be able to measure about things, and that sometimes seems
• 20:08
  Speaker 3: to be conserved.
• 20:09
  Speaker 1: So mathematically, we can write down a formula that defines it,
• 20:12
  Speaker 1: and then it's defined in terms of things we can
• 20:14
  Speaker 1: measure like velocity and position and stuff like this. And
• 20:18
  Speaker 1: it turns out that if you write it in certain ways,
• 20:20
  Speaker 1: then that number doesn't change. The internal values can slash
• 20:24
  Speaker 1: back and forth, but the total doesn't change. That's sort
• 20:27
  Speaker 1: of like the crispest most mathematical definition. But I think
• 20:30
  Speaker 1: what we're proving forward is like what does it mean philosophically?
• 20:33
  Speaker 1: Like what are the implications of that? And that's much trickier.
• 20:36
  Speaker 3: Well, you seem to not want to give primacy to
• 20:38
  Speaker 3: kinetic energy, but in a way, that's kind of like
• 20:41
  Speaker 3: our most direct experience of energy, which is motion, right,
• 20:45
  Speaker 3: Like if something has a lot of energy to either
• 20:47
  Speaker 3: moving fast, or it's hot or it's exploding. For us,
• 20:51
  Speaker 3: in our experience of the universe, energy is basically things
• 20:54
  Speaker 3: moving fast or things that can make things move fast.
• 20:57
  Speaker 1: Yeah, if you're talking about the experience of it, then
• 20:59
  Speaker 1: you more directly experience motion than stored energy. It's energy
• 21:05
  Speaker 1: you don't really experience when it's stored because it's just
• 21:07
  Speaker 1: being stored. It's when it's transformed into kinetic energy that
• 21:10
  Speaker 1: you're experiencing it. Like if you zap yourself on a battery,
• 21:13
  Speaker 1: it's the motion of those electrons being transformed from the
• 21:16
  Speaker 1: potential into their kinetic energy that's zapping you.
• 21:19
  Speaker 3: All right. So then you said that sometimes it's conserved
• 21:22
  Speaker 3: and sometimes it's not. So when is energy conserved in
• 21:26
  Speaker 3: a classical way?
• 21:27
  Speaker 1: In classical sense, energy is only conserved when space time
• 21:31
  Speaker 1: is not curved and when space time is not changing.
• 21:34
  Speaker 1: So if space time is fixed, like you have flat
• 21:37
  Speaker 1: space time, meaning you shoot two photons and they stay
• 21:40
  Speaker 1: parallel to each other, then you can expect energy to
• 21:43
  Speaker 1: be conserved. But if that space is changing, like it's
• 21:45
  Speaker 1: expanding the way our universe is, then the general relativity,
• 21:49
  Speaker 1: energy is not conserved. Even more generally, anytime you have
• 21:52
  Speaker 1: curved space in general relativity, you do not have conservation
• 21:56
  Speaker 1: of energy. So, for example, black holes colliding do not
• 22:00
  Speaker 1: conserve energy.
• 22:01
  Speaker 3: Wait, what what do you mean.
• 22:02
  Speaker 1: When two black holes collide? You have the collision of
• 22:04
  Speaker 1: two curved bits of space, and what comes out of
• 22:06
  Speaker 1: that is not the sum of what goes into that.
• 22:09
  Speaker 1: You're not guaranteed that in general relativity.
• 22:11
  Speaker 3: But is in space always curved like uncurving space around me,
• 22:16
  Speaker 3: and yet I don't seem to have infinite energy.
• 22:18
  Speaker 1: That's right, you do not have infinite energy and you
• 22:20
  Speaker 1: are curving space around you. But the total amount of
• 22:23
  Speaker 1: energy in the system changes in time in general relativity,
• 22:27
  Speaker 1: and it gets really fuzzy and weird because general relativity
• 22:30
  Speaker 1: is really hard to think about in some reference frames.
• 22:32
  Speaker 1: According to generalativity, energy is conserved in others, it's not.
• 22:35
  Speaker 1: Depends sort of on how you're looking at things.
• 22:37
  Speaker 3: Okay, it sort of sounds like you're saying like, if
• 22:40
  Speaker 3: you don't think about general relativity, then you can assume
• 22:43
  Speaker 3: that energy is being conserved. If you assume that there's
• 22:46
  Speaker 3: general relativity and things are being space is being bent
• 22:49
  Speaker 3: like around black holes or the expansion of the universe.
• 22:52
  Speaker 3: Then you can't assume that energy is being conserved.
• 22:54
  Speaker 1: As long as we're above the quantum level.
• 22:56
  Speaker 3: Right, So it's mostly like whether or not you ignore
• 22:59
  Speaker 3: the bunding of space exactly.
• 23:00
  Speaker 1: If you can ignore the bending or expansion of space time,
• 23:03
  Speaker 1: then classically you can think of energy as conserved.
• 23:06
  Speaker 3: Right. And so we talked about that the universe is
• 23:08
  Speaker 3: expanding and so therefore energy is not being concernedd and
• 23:11
  Speaker 3: we talked about two black holes colliding. Energy is not
• 23:14
  Speaker 3: being conserved there So now the question of the episode
• 23:16
  Speaker 3: is when you get down to the quantum level, is
• 23:19
  Speaker 3: energy still conserved even though maybe there's no space time
• 23:23
  Speaker 3: bending at the quantum level. If you assume there's no
• 23:26
  Speaker 3: bending at the quantum level, does energy get conserved.
• 23:30
  Speaker 1: Yeah, And we have to assume there's no space time
• 23:32
  Speaker 1: bending at the quantum level because we don't know how
• 23:34
  Speaker 1: to do quantum mechanics when space is curved and you
• 23:36
  Speaker 1: have gravity, and gravity for particles is something we don't understand.
• 23:40
  Speaker 1: So let's assume space is totally flat and we have objects,
• 23:43
  Speaker 1: you know, like baseballs and rocks for which we think
• 23:47
  Speaker 1: energy is conserved and then zoomed down to the quantum
• 23:49
  Speaker 1: level and try to understand when you have photons and
• 23:52
  Speaker 1: electrons instead of rocks and baseballs, is energy still conserved?
• 23:56
  Speaker 1: And really the deep question is like, is energy conservation
• 23:59
  Speaker 1: something that's through in through the universe at every scale
• 24:02
  Speaker 1: or is this something that emerges only at the scale
• 24:04
  Speaker 1: we experience it out of something that operates totally differently,
• 24:07
  Speaker 1: because remember, quantum mechanics breaks all the rules of classical physics.
• 24:11
  Speaker 1: It says things don't actually have well defined positions and locations,
• 24:14
  Speaker 1: and lots of the things that emerge at our level
• 24:16
  Speaker 1: are not true at the quantum level. So it's not
• 24:18
  Speaker 1: guaranteed that everything about our experience will be translated down
• 24:22
  Speaker 1: to the quantum level.
• 24:23
  Speaker 3: All right, So then let's answer the question, does quantum
• 24:25
  Speaker 3: mechanics can serve energy or not?
• 24:27
  Speaker 1: So the short answer is we don't know.
• 24:29
  Speaker 3: Surprise, surprise, But let's talk about it anyways.
• 24:32
  Speaker 1: The slightly less short answer is it depends on what
• 24:35
  Speaker 1: you think is happening at the quantum level, mostly about
• 24:38
  Speaker 1: what happens when you try to measure energy.
• 24:40
  Speaker 3: What do you mean? So I guess, because it's quantum mechanics,
• 24:44
  Speaker 3: you have to measure things. That's very importing quantum mechanics.
• 24:47
  Speaker 3: So you're saying, we have to answer this question with
• 24:49
  Speaker 3: this idea in mind.
• 24:50
  Speaker 1: Yeah, exactly. So let's start off the easy case without
• 24:53
  Speaker 1: measurements and have a picture in our minds or what's happening.
• 24:56
  Speaker 1: You know, quantum mechanics tells us that there are probabilities
• 24:59
  Speaker 1: for various things to happen, and we can calculate those
• 25:02
  Speaker 1: probabilities using the rules of quantum mechanics, and those probabilities propagate.
• 25:06
  Speaker 1: You have two electrons heading towards each other, they might
• 25:09
  Speaker 1: scatter off each other and go that way, they might
• 25:11
  Speaker 1: pass right through each other. All those probabilities are sort
• 25:15
  Speaker 1: of live until somebody actually asks the question and makes
• 25:18
  Speaker 1: a measurement using a classical object and you know, tries
• 25:21
  Speaker 1: to take a picture of it. Until then sort of
• 25:24
  Speaker 1: have all the possibilities live. So that's quantum mechanics without measurement.
• 25:28
  Speaker 1: You know, that's what we're imagining is happening when we're
• 25:30
  Speaker 1: not looking. And in that scenario we can ask, well,
• 25:34
  Speaker 1: is energy conserved? Like when all those probabilities are slashing around,
• 25:38
  Speaker 1: the electrons are maybe bouncing off each other and maybe
• 25:41
  Speaker 1: not is energy conserved there? And already we kind of
• 25:44
  Speaker 1: run into trouble because we don't really know how to
• 25:47
  Speaker 1: define energy here. Like, what if you have a quantum
• 25:51
  Speaker 1: system and has a few different possible states, a low
• 25:54
  Speaker 1: energy state and a high energy state. How do you
• 25:57
  Speaker 1: define the energy of it? Is it like the way
• 26:00
  Speaker 1: average of the probabilities of the various states? Is it
• 26:04
  Speaker 1: something else. I've had conversations with a bunch of physicists
• 26:06
  Speaker 1: this week to try to sort out what people think
• 26:09
  Speaker 1: energy is, and some people say, you can't define energy
• 26:11
  Speaker 1: in that context, and other people say, no, it's definitely
• 26:14
  Speaker 1: the weighted average of the various probabilities.
• 26:16
  Speaker 3: Right, I think, meaning maybe for people who are not
• 26:18
  Speaker 3: super familiar with quantum mechanics. So in quantum mechanics, particles
• 26:22
  Speaker 3: and things like that aren't just in one state, like
• 26:24
  Speaker 3: a baseball sitting on your table. It's like it's doing
• 26:27
  Speaker 3: multiple things at the same time. It's here, it's a
• 26:29
  Speaker 3: little bit there, it's moving in this direction a little bit,
• 26:31
  Speaker 3: but it's also has the probability to be moving in
• 26:34
  Speaker 3: this other direction. And so you're saying that maybe one
• 26:37
  Speaker 3: way to measure its energy, or to think about its
• 26:39
  Speaker 3: energy is like, if it has a fifty percent probability
• 26:42
  Speaker 3: of going this way, then you take that energy and
• 26:45
  Speaker 3: multiply by a half. And if it has a certain
• 26:48
  Speaker 3: probility that it's moving this way with that velocity, like
• 26:51
  Speaker 3: a twenty five percent probability, then you maybe multiply that
• 26:54
  Speaker 3: energy by a quarter, and then you would add it
• 26:56
  Speaker 3: all up and maybe that would kind of give you
• 26:58
  Speaker 3: an average of it energy.
• 27:00
  Speaker 1: Yeah, exactly, Like if it has a fifty percent chance
• 27:03
  Speaker 1: of having twenty five jewels of energy and a fifty
• 27:05
  Speaker 1: percent chance of having seventy five jewels, then you say, well,
• 27:08
  Speaker 1: I'm going to average those two. I'm gonna say its
• 27:10
  Speaker 1: energy is fifty jewels because on average that's what it has.
• 27:13
  Speaker 1: And here allowing the particle to still have both probabilities
• 27:16
  Speaker 1: to say, oh, maybe it's in the lower energy state,
• 27:18
  Speaker 1: maybe it's in the higher energy state.
• 27:20
  Speaker 3: Right, it's in a superposition, it's with a life and dead.
• 27:23
  Speaker 3: Then you said, some of your physicist friends said, you
• 27:25
  Speaker 3: can't do that, like that's not even that doesn't make sense.
• 27:27
  Speaker 1: Yeah, And they say, you can't do that because you
• 27:30
  Speaker 1: can't measure that, right, you never measure the fifty Like
• 27:32
  Speaker 1: if you went and asked the question, all right, we
• 27:35
  Speaker 1: have the particle in this state, go measure the energy.
• 27:37
  Speaker 1: You're gonna get twenty five or you're gonna get seventy five.
• 27:39
  Speaker 1: You're never going to get the average. It's like saying
• 27:42
  Speaker 1: the average number of children in the US is two
• 27:44
  Speaker 1: point four, but nobody actually has two point four children, right,
• 27:48
  Speaker 1: and so in the same way, you'll never see this
• 27:50
  Speaker 1: particle have that energy. So in what sense is that
• 27:52
  Speaker 1: the energy of the particle? That's sort of the complaint.
• 27:55
  Speaker 3: That's kind of a fundamental problem with quantum mechanics. Like
• 27:58
  Speaker 3: it's you know, the cat is alive and dead. Obviously
• 28:00
  Speaker 3: the cat can't be alive if you see the cat.
• 28:03
  Speaker 3: It can't be both. But in a quantum sense, it
• 28:06
  Speaker 3: is both.
• 28:06
  Speaker 1: In a quantum sense, it is both. In quantum sense,
• 28:08
  Speaker 1: we need a new idea for what these things mean,
• 28:11
  Speaker 1: Like what does position mean in a quantum sense, Well,
• 28:14
  Speaker 1: you know, for a particle that you haven't measured, it's
• 28:16
  Speaker 1: not really well defined. There's only a probability where is
• 28:19
  Speaker 1: the particle Actually, well, it's not anywhere. Actually, So these
• 28:23
  Speaker 1: concepts that are so important to us at the macroscopic
• 28:26
  Speaker 1: scale have to take different meanings. We have to do
• 28:29
  Speaker 1: this like philosophical extrapolation, and this is a problem with energy.
• 28:33
  Speaker 1: For example, say we have the particle and has two
• 28:35
  Speaker 1: different possibilities, the twenty five jewel and the seventy five jewel.
• 28:38
  Speaker 1: Then you go and you measure and it turns out
• 28:39
  Speaker 1: it has seventy five jewels. Well, if a minute ago
• 28:42
  Speaker 1: you said it had fifty jewels because that was the average.
• 28:44
  Speaker 1: Now you've measured it and you said you have seventy
• 28:46
  Speaker 1: five jewels. Where did that twenty five jewels come from?
• 28:49
  Speaker 3: Right?
• 28:49
  Speaker 1: And so boom right there, you have a violation of
• 28:52
  Speaker 1: conservation of energy. If that's how you define energy before
• 28:56
  Speaker 1: you measure it.
• 28:56
  Speaker 3: Wait, say it again. It is energy suddenly appear.
• 28:59
  Speaker 1: So if you start out the particle we were just
• 29:00
  Speaker 1: talking about, it has a fifty percent chance of having
• 29:03
  Speaker 1: twenty five jewels and a fifty percent chance of having
• 29:05
  Speaker 1: seventy five jewels. So we say, okay, we define the
• 29:08
  Speaker 1: energy of it to be fifty jewels because that's the average.
• 29:10
  Speaker 1: Now you go and you measure it, and you measure
• 29:12
  Speaker 1: it to have seventy five jewels for example, Then according
• 29:15
  Speaker 1: to our definition of energy, it's gone from having fifty
• 29:17
  Speaker 1: jewels to having seventy five jewels, and so where did
• 29:20
  Speaker 1: that energy come from?
• 29:22
  Speaker 3: It didn't come from anywhere, it just said before it
• 29:24
  Speaker 3: was a guess about what its energy was. It was
• 29:26
  Speaker 3: kind of like the expectations of it or the average
• 29:29
  Speaker 3: of what we think its energy was. But then in
• 29:31
  Speaker 3: the second instance, is what we measured its energy. So
• 29:35
  Speaker 3: they shouldn't be a surprise if it's more or less,
• 29:37
  Speaker 3: should it?
• 29:37
  Speaker 1: So you're saying, those are really two different things. One
• 29:40
  Speaker 1: is an actual energy because you've measured it. The other
• 29:42
  Speaker 1: is just some estimation of what we might measure, but
• 29:45
  Speaker 1: not really the energy.
• 29:46
  Speaker 3: Well, and it is in the quantum sense right like
• 29:49
  Speaker 3: it's alive and it's dead before I look at the
• 29:52
  Speaker 3: cat in the box and then I wanted to open
• 29:54
  Speaker 3: the box. It's alive with it. It's not like the
• 29:57
  Speaker 3: cat suddenly came back to life.
• 29:59
  Speaker 1: And I think this comes down to a question of
• 30:01
  Speaker 1: like interpretation, You know, what is really happening there? It
• 30:04
  Speaker 1: does the particle secretly already have seventy five jewels and
• 30:07
  Speaker 1: now we're measuring it and discovering it. You know, is
• 30:09
  Speaker 1: the uncertainty there or reflection of our lack of knowledge
• 30:13
  Speaker 1: about something that's actually already determined or something that really
• 30:16
  Speaker 1: isn't determined until we measure it. The particle really is
• 30:20
  Speaker 1: in a superposition of those two states. If it really
• 30:22
  Speaker 1: isn't determined until we measure it, then we do have
• 30:24
  Speaker 1: to kind of ask, like, where does the energy come
• 30:26
  Speaker 1: from when the universe decides to make that seventy five
• 30:29
  Speaker 1: jewel particle instead of the twenty five jewel particle.
• 30:32
  Speaker 3: Well, I guess in the same way that you can
• 30:33
  Speaker 3: ask if you find that the cat is alive, how
• 30:36
  Speaker 3: did the cat come alive? It was if it was
• 30:38
  Speaker 3: alive and dead before you open the box.
• 30:40
  Speaker 1: Right, But the difference between the two states of the
• 30:42
  Speaker 1: cat doesn't violate the conservation of energy, which we thought
• 30:45
  Speaker 1: was maybe a fundamental rule in the universe. That violates
• 30:48
  Speaker 1: the conservation of the number of dead cats, which nobody
• 30:50
  Speaker 1: really thinks it's a.
• 30:52
  Speaker 3: Conservation I hope not well or well, And this says
• 30:55
  Speaker 3: that we think that it's impossible for a cat to
• 30:57
  Speaker 3: go from being dead to being alive.
• 30:59
  Speaker 1: Right, I think if we're going to make the analogy
• 31:01
  Speaker 1: to the shorten your cat experiment, and then you want
• 31:03
  Speaker 1: to ask the question, is the cat alive before it's measured,
• 31:06
  Speaker 1: And the answer I think a lot of people would
• 31:07
  Speaker 1: give is it's neither alive nor dead. It has the
• 31:09
  Speaker 1: probability of being both. And then to extrapolate that philosophically
• 31:13
  Speaker 1: back to our particle, you'd say, well, the particle doesn't
• 31:16
  Speaker 1: really have twenty five or seventy five jewels, It just
• 31:18
  Speaker 1: has a probability of being both. And energy is not
• 31:21
  Speaker 1: really well defined. So I think one answer there is
• 31:24
  Speaker 1: to say, well, energy is not really defined without measurements,
• 31:27
  Speaker 1: so you can't answer this question, and the others to say, no,
• 31:30
  Speaker 1: that's the definition of energy, and there is violation of
• 31:32
  Speaker 1: conservation of energy, So you either have to give up
• 31:35
  Speaker 1: an understanding of what energy means for quantum particles or
• 31:38
  Speaker 1: you have to give up energy conservation.
• 31:40
  Speaker 3: All right, So it seems like the moment you measure
• 31:43
  Speaker 3: a quantum particle is super important because it's so fuzzy
• 31:47
  Speaker 3: before you measure it, and it's so crisp after you
• 31:50
  Speaker 3: measure it, and so you kind of fall into a
• 31:52
  Speaker 3: trap to try to compare the energy before that moment
• 31:54
  Speaker 3: and after that moment, you know, you could interpret it
• 31:57
  Speaker 3: as saying that energy is not conserved or could interpret
• 32:00
  Speaker 3: it saying, well, you know, there's no definition of energy
• 32:04
  Speaker 3: before you measure it, and so therefore don't even worry
• 32:07
  Speaker 3: about energy classivation exactly.
• 32:10
  Speaker 1: But there's really important loophole that we're overlooking here, and
• 32:13
  Speaker 1: that's the measurement itself. Some people argue that energy isn't conserved,
• 32:18
  Speaker 1: that this extra energy must come from the measurement, that
• 32:21
  Speaker 1: we're only violating conservation of energy because we're not including
• 32:24
  Speaker 1: the full system. Right. Energy is only conserved inside a
• 32:27
  Speaker 1: closed system where you don't have energy transfer anyway. Right,
• 32:30
  Speaker 1: Like energy is not conserved for a battery. As you
• 32:33
  Speaker 1: use it, it's energy is decreasing, but if you include
• 32:35
  Speaker 1: where that energy is going, usually it is concerned. So
• 32:38
  Speaker 1: some people argue, ah, what about the measurement. In order
• 32:41
  Speaker 1: to measure something, you have to like poke it, you
• 32:43
  Speaker 1: have to interact with it. Maybe you're adding that energy
• 32:46
  Speaker 1: when you're making that measurement and things do balance out
• 32:49
  Speaker 1: in the end.
• 32:50
  Speaker 3: Wait what that was very confusing? Can you give me
• 32:53
  Speaker 3: an example.
• 32:54
  Speaker 1: So let's say you want to measure this particle and
• 32:56
  Speaker 1: you want to say it doesn't have seventy five jewels
• 32:58
  Speaker 1: or twenty five jewels, How do you measure things about
• 33:00
  Speaker 1: a quantum particle, you have to bounce another quantum particle
• 33:02
  Speaker 1: off of them. So shoot this electron with a photon,
• 33:06
  Speaker 1: then measure where that photon goes and use that to
• 33:08
  Speaker 1: detect what the energy of your particle was. Well, now
• 33:11
  Speaker 1: you're shooting your electron with a photon, which is going
• 33:13
  Speaker 1: to change its energy. And so people argue, when you're
• 33:17
  Speaker 1: doing this, the energy that gives that electron seventy five
• 33:20
  Speaker 1: jewels comes from that photon somehow.
• 33:22
  Speaker 3: But then wouldn't you measure that the overall energy went
• 33:26
  Speaker 3: down because you would measure the photon after it hits
• 33:28
  Speaker 3: the electron, and you would see that it was had
• 33:30
  Speaker 3: less energy exactly.
• 33:32
  Speaker 1: So this is the game people try to play in
• 33:34
  Speaker 1: order to recover conservation of energy for quantum mechanics. They say,
• 33:37
  Speaker 1: this argument is flawed because you're not taking into account
• 33:39
  Speaker 1: the energy of the measurement. So there's a whole cottage
• 33:42
  Speaker 1: industry and a bunch of paper. It's recently about whether
• 33:45
  Speaker 1: it's possible to recover it using the measurement or whether
• 33:47
  Speaker 1: that's a red herring.
• 33:48
  Speaker 3: Well, the whole thing could be a red herring, right,
• 33:50
  Speaker 3: Like it could be that it just doesn't make sense
• 33:52
  Speaker 3: to talk about energy before the measurement.
• 33:54
  Speaker 1: It could be and that actually depends also on your
• 33:56
  Speaker 1: interpretation of quantum mechanics. We're talking right now in the
• 34:00
  Speaker 1: Copenhagen interpretation, which has this whole idea that there's a
• 34:03
  Speaker 1: superposition and when you make a measurement it collapses to
• 34:05
  Speaker 1: one of those options. That's just one view of quantum mechanics,
• 34:09
  Speaker 1: and our argument about the energy non conservation depends on
• 34:13
  Speaker 1: that view. It turns out in other views of quantum
• 34:15
  Speaker 1: mechanics they tell a whole different story.
• 34:18
  Speaker 3: All right, well, let's get into what these other views
• 34:20
  Speaker 3: of quantum mechanics are and what they say about the
• 34:24
  Speaker 3: conservation of cat energy or not. So let's dig into that.
• 34:27
  Speaker 3: But first let's take another quick break. All Right, we're
• 34:43
  Speaker 3: talking about energy, whether it's conserved in the universe, is
• 34:47
  Speaker 3: it conserved at the quantum level? And I think we've
• 34:49
  Speaker 3: established that it's a minefield of confusion for everybody. Some
• 34:55
  Speaker 3: people might say, does it even make sense to talk
• 34:57
  Speaker 3: about energy before you measure something? And you know, it
• 35:01
  Speaker 3: doesn't make sense to talk about whether the cat is
• 35:03
  Speaker 3: alive or dead before you open the box. And some
• 35:07
  Speaker 3: people might say that it does kind of matter, right,
• 35:10
  Speaker 3: or that if you discovered the cat to be aliver
• 35:12
  Speaker 3: before or after, maybe you killed the cat when you
• 35:14
  Speaker 3: open the box. That's kind of what you're saying exactly.
• 35:17
  Speaker 1: And it's amazing to me that this is a topic
• 35:19
  Speaker 1: of recent discussion. This is not like something that Bore
• 35:22
  Speaker 1: and Heisenberg argued about and figured it out in nineteen
• 35:25
  Speaker 1: thirty seven their papers about this. Like last year, you know,
• 35:29
  Speaker 1: people are still debating what energy even means in quantum mechanics. Like,
• 35:33
  Speaker 1: sort this out, folks. You had it for one hundred years.
• 35:35
  Speaker 1: You think that would be enough time to figure out
• 35:37
  Speaker 1: basic stuff about quantum mechanics.
• 35:39
  Speaker 3: Yeah, can't you just run an experiment to figure this out?
• 35:41
  Speaker 3: Like if measuring an electron somehow adds energy to it
• 35:46
  Speaker 3: or creates energy, can't you just measure that cad you
• 35:49
  Speaker 3: just design an experiment where you should a photon at
• 35:51
  Speaker 3: an electron.
• 35:52
  Speaker 1: So people are trying to design experiments, and the crucial
• 35:54
  Speaker 1: thing is designing an experiment where you think the measurement
• 35:58
  Speaker 1: will not influence the energy of the system. That's the goal,
• 36:02
  Speaker 1: because then you can have an internal system and an
• 36:04
  Speaker 1: external system, and you can isolate it and say this
• 36:06
  Speaker 1: is the whole system. So you want to try to
• 36:08
  Speaker 1: separate your measuring device from the energy of the system.
• 36:11
  Speaker 3: Wait, wait, do you mean like they're trying to come
• 36:12
  Speaker 3: up with how to measure something without measuring it.
• 36:14
  Speaker 1: Well, they want to measure it without changing its energy,
• 36:17
  Speaker 1: so they want a energy independent measuring system.
• 36:21
  Speaker 3: But I guess, if you shoot a photon at an electron,
• 36:23
  Speaker 3: don't you know how much energy the photon had when
• 36:25
  Speaker 3: you shot it so that you can take it into
• 36:28
  Speaker 3: account later when it comes out? Like, why is this
• 36:31
  Speaker 3: problem so hard?
• 36:32
  Speaker 1: Well, every quantum object has an uncertainty to it, and
• 36:34
  Speaker 1: so you shoot a photon at it. You try to
• 36:36
  Speaker 1: generate photons with a specific energy, but those photons will
• 36:39
  Speaker 1: also have an uncertainty to them, and that uncertainty propagates
• 36:42
  Speaker 1: through your whole experiment. So what you want to try
• 36:44
  Speaker 1: to do is set up a scenario where the uncertainty
• 36:46
  Speaker 1: you're adding by your measurement is smaller than the difference
• 36:50
  Speaker 1: in the energy between the two states of the thing
• 36:52
  Speaker 1: that you're measuring. So you want to try to use
• 36:55
  Speaker 1: something really low energy to measure a really big difference.
• 36:58
  Speaker 3: I guess it's kind of like you know, you're trying
• 36:59
  Speaker 3: to figure out if the cat is alive or dead
• 37:01
  Speaker 3: in the box, and you're sending it in a cat
• 37:03
  Speaker 3: to do it. But it turns out that the scientist
• 37:05
  Speaker 3: cat is also a quantum object, so it could also
• 37:08
  Speaker 3: be a live or dead, in which case you don't
• 37:10
  Speaker 3: really know the scientist cat is killing the other cat exactly.
• 37:13
  Speaker 1: So what you want to do is try to send
• 37:14
  Speaker 1: in like a tiny miniature kitten that you can argue
• 37:18
  Speaker 1: is going to not influence whether your cat is alive
• 37:20
  Speaker 1: or dead as much.
• 37:21
  Speaker 3: As possible, or that you know for sure if it's
• 37:24
  Speaker 3: alive or dead.
• 37:25
  Speaker 1: Or the uncertainty on it is smaller than the uncertainty
• 37:27
  Speaker 1: on the thing you're trying to measure. So people come
• 37:29
  Speaker 1: up with these crazy clever experiments where you try to
• 37:32
  Speaker 1: use really low energy device to measure a very high
• 37:36
  Speaker 1: energy difference in the possible states of the object. So
• 37:39
  Speaker 1: the thing you're measuring is not influencing the state enough
• 37:42
  Speaker 1: to change the answer.
• 37:44
  Speaker 3: Oh I see, yeah, Like you said, like you want
• 37:45
  Speaker 3: to send in a scientist kitty whose state whether the
• 37:49
  Speaker 3: kitty is a live or dead is not really going
• 37:51
  Speaker 3: to influence whether the big cat is a live or
• 37:54
  Speaker 3: dead exactly.
• 37:56
  Speaker 1: And so there's these folks that come up with its
• 37:58
  Speaker 1: really clever experience where you take a box and you
• 38:01
  Speaker 1: put low energy photons inside of it, and under some
• 38:05
  Speaker 1: almost magic like wave mechanics mathematics, there's a place in
• 38:09
  Speaker 1: the box where the photon wavelengths add up in a
• 38:11
  Speaker 1: special way to wiggle at a really high energy. So
• 38:14
  Speaker 1: waves can add up and they can cancel each other out.
• 38:17
  Speaker 1: This is constructive and destructive interference, where it turns out
• 38:20
  Speaker 1: if you put a bunch of low energy photons into
• 38:22
  Speaker 1: a box, there's one portion of the box where they're
• 38:25
  Speaker 1: wiggling really really fast where all those photons added up
• 38:29
  Speaker 1: kind of make a higher energy photon than the sum
• 38:31
  Speaker 1: of all the energy of the photons you put in.
• 38:35
  Speaker 1: And they came up with this way to try to
• 38:36
  Speaker 1: reflect that one part of the photon out of the
• 38:39
  Speaker 1: box by slipping a mirror in really quick. And so
• 38:42
  Speaker 1: it's sort of like putting a few low energy photons
• 38:44
  Speaker 1: in a box and then getting out a really high
• 38:46
  Speaker 1: energy photon. So this is the experiment they propose would
• 38:50
  Speaker 1: prove violation or conservation of energy and quantum mechanics. But
• 38:53
  Speaker 1: there's a lot of controversy about what this experiment might
• 38:56
  Speaker 1: mean and whether you could actually do it.
• 38:58
  Speaker 3: Oh, I see, because if you measure a really big
• 39:01
  Speaker 3: photon coming out of this corner of the box, you
• 39:03
  Speaker 3: have to wonder where that energy came from.
• 39:05
  Speaker 1: Yeah, how did the universe make this high energy photon
• 39:08
  Speaker 1: out of just a few very low energy photons? Where
• 39:10
  Speaker 1: did it come from? Just like the example we were
• 39:12
  Speaker 1: talking about before, how did the particle get seventy five
• 39:15
  Speaker 1: GeV when the expected value of the energy was fifty
• 39:18
  Speaker 1: Where did that energy come from? And you can only
• 39:20
  Speaker 1: really ask that question where did it come from if
• 39:23
  Speaker 1: you believe it should come from somewhere, which implies that
• 39:25
  Speaker 1: it's conserved, that it has to come from somewhere, that
• 39:28
  Speaker 1: it's like flows around in it's a limited amount. But
• 39:30
  Speaker 1: if energy is not conserved, it can just like go
• 39:32
  Speaker 1: up or down, like the number of dead cats in
• 39:34
  Speaker 1: the universe. Then that's not really a problem.
• 39:36
  Speaker 3: But couldn't you just say that the energy of that
• 39:38
  Speaker 3: right photon in the corner came from the little photons
• 39:41
  Speaker 3: or would it come out with a much bigger energy
• 39:43
  Speaker 3: than the if you add up the little smaller photons.
• 39:46
  Speaker 1: Yeah, in this case, the energy is much bigger than
• 39:49
  Speaker 1: the sum of the energies of all the photons you
• 39:51
  Speaker 1: put in, So you can't explain it by just like
• 39:53
  Speaker 1: having added up those photons. It's a really cool experiment.
• 39:56
  Speaker 1: It's called super oscillation if you want to check out
• 39:59
  Speaker 1: more details about it.
• 40:00
  Speaker 3: Well, but then you said that this is all just
• 40:02
  Speaker 3: base on one interpretation of quantum mechanics. What did the
• 40:06
  Speaker 3: other interpretations say or how can they help us?
• 40:08
  Speaker 1: Yeah, because a big part of the issue is what
• 40:10
  Speaker 1: happens when you make a measurement. Right if you go
• 40:12
  Speaker 1: from a state that has on average fifty jewels of energy,
• 40:15
  Speaker 1: then you make a measurement, how do you end up
• 40:17
  Speaker 1: in one of those states? And where does that energy
• 40:19
  Speaker 1: come from? And other interpretations of quantum mechanics tell a
• 40:22
  Speaker 1: very different story about what's happening there. For example, the
• 40:25
  Speaker 1: Many Worlds or ever Ready in quantum mechanics says that
• 40:28
  Speaker 1: there is no collapse of the wave function. That if
• 40:31
  Speaker 1: you have a superposition of two possibilities that has alive
• 40:34
  Speaker 1: or dead, the particle has twenty five or seventy five
• 40:37
  Speaker 1: jewels of energy, that when you make a measurement, the
• 40:40
  Speaker 1: universe just branches and now there's one branch that has
• 40:42
  Speaker 1: one option and another branch that has the other option.
• 40:44
  Speaker 1: And so in that sense, if you're like averaging over
• 40:47
  Speaker 1: the branches, nothing has really changed. You know, the total
• 40:50
  Speaker 1: energy in the universe hasn't changed. One individual branch might
• 40:53
  Speaker 1: see seventy five jewels, so they might think they're seeing
• 40:57
  Speaker 1: violation of conservation of energy. But averaged over all the branches,
• 41:00
  Speaker 1: including the ones that don't see, nothing has really changed.
• 41:03
  Speaker 1: There's still just a distribution of different energies.
• 41:05
  Speaker 3: I feel like you just skipped over a humongas concept
• 41:09
  Speaker 3: which is just throwing the multiverse.
• 41:11
  Speaker 1: Yes, exactly, in the multiverse.
• 41:12
  Speaker 3: Quantum multiverse. So you're saying, like, one way to interpret
• 41:16
  Speaker 3: quantum mechanics is that things don't collapse. You know, if
• 41:19
  Speaker 3: something if the cat is alive and dead, it means
• 41:21
  Speaker 3: that there's a universe where the cat is alive and
• 41:23
  Speaker 3: there's a universe where it's dead, and so overall energy
• 41:27
  Speaker 3: is still conserved. That's kind of the idea.
• 41:28
  Speaker 1: Yeah, energy is just unevenly distributed among those quantum multiverses.
• 41:34
  Speaker 1: One of them gets more, another one gets less. Overall
• 41:37
  Speaker 1: it all balances out across the multiverse. But in an
• 41:40
  Speaker 1: individual universe, an observer does see a violation of energy.
• 41:44
  Speaker 1: So that's a pretty different story than what's being told
• 41:46
  Speaker 1: by the Copenhagen group.
• 41:47
  Speaker 3: Let me see if I get this, so, like, I
• 41:49
  Speaker 3: have the cat in the box, and I open the
• 41:51
  Speaker 3: box and I find that the cat is alive, and
• 41:53
  Speaker 3: I think, oh my god, this is a violation of
• 41:55
  Speaker 3: cat aliveness in the universe because before the cat was
• 41:59
  Speaker 3: only fifty percent and now it's fully alive.
• 42:01
  Speaker 1: Sure.
• 42:02
  Speaker 3: Yeah, And you're saying, if you think that the actually
• 42:06
  Speaker 3: there's a multiverse, is a quantum multiverse, then there's no
• 42:09
  Speaker 3: real violation because if you consider my universe where the
• 42:12
  Speaker 3: cat is alive and your universe where the cat is dead,
• 42:15
  Speaker 3: then it makes sense for me to see that the
• 42:18
  Speaker 3: cat is alive, and it makes sense for you to
• 42:19
  Speaker 3: see that the cat is dead. There's no violation here.
• 42:21
  Speaker 1: Yeah, because across the quantum multiverse it's still fifty percent
• 42:24
  Speaker 1: alive and fifty percent dead.
• 42:26
  Speaker 3: But in the single universe version of quantum mechanics, the
• 42:30
  Speaker 3: cat aliveness went up from one half to one if
• 42:33
  Speaker 3: I see that the cat.
• 42:34
  Speaker 1: Is alive exactly. So in the collapse theory where measuring
• 42:38
  Speaker 1: it forces the universe to choose one of these branches
• 42:41
  Speaker 1: instead of maintaining all of them, then somehow the number
• 42:44
  Speaker 1: of live cats in the universe goes up from half
• 42:46
  Speaker 1: to one, violating the well known principle of the number
• 42:49
  Speaker 1: of living cats in the universe.
• 42:51
  Speaker 3: Yeah, or people in swimming pools, which I'm going to
• 42:54
  Speaker 3: wait for that paper from me. Okay, hold your breas, yeah,
• 43:00
  Speaker 3: to under the pool. Yes, Okay. So then I feel
• 43:02
  Speaker 3: like maybe I wonder, like you're saying, if we require
• 43:07
  Speaker 3: energy to be conserved in the universe for real, for sure,
• 43:11
  Speaker 3: then maybe I wonder if that's proof that the multiverse exists,
• 43:15
  Speaker 3: because that's the only way that this is going to work.
• 43:17
  Speaker 1: Right, That's a cool perspective I hadn't thought of. Yeah,
• 43:19
  Speaker 1: I suppose if you define energy that way as across
• 43:23
  Speaker 1: the multiverse and you insist that it's conserved, then Copenhagen
• 43:29
  Speaker 1: interpretation of quantum mechanics does violate that. But that's not
• 43:31
  Speaker 1: something you can test, right. You can never access these
• 43:34
  Speaker 1: other branches of the multiverse. You can never know if
• 43:37
  Speaker 1: they exist, and if other people are measuring other things,
• 43:40
  Speaker 1: then you can only ever access our branch.
• 43:42
  Speaker 3: We think, maybe, right, maybe you can this. I think
• 43:46
  Speaker 3: we've talked about this before and in our books, like
• 43:49
  Speaker 3: you could maybe discover something about the mathematics of our
• 43:52
  Speaker 3: universe that maybe points to the necessity of other universes.
• 43:55
  Speaker 1: No, we definitely argue in our book that it might
• 43:58
  Speaker 1: be that the only consistent explanation of the universe is
• 44:01
  Speaker 1: the multiverse. So you can prove the multiverse exists without
• 44:05
  Speaker 1: ever experimentally verifying it, though that takes a lot of
• 44:08
  Speaker 1: confidence to say that there's no other explanation out there.
• 44:11
  Speaker 3: That would take a high amount of confidence, not a
• 44:14
  Speaker 3: nuclear amount of confidence.
• 44:15
  Speaker 1: So extrapolining that argument, if you can somehow prove that
• 44:18
  Speaker 1: a complete theory of the universe has to satisfy conservation
• 44:21
  Speaker 1: of energy at the quantum level, then yeah, that might
• 44:24
  Speaker 1: require the existence of the multiverse. But I don't know
• 44:26
  Speaker 1: how you would prove that requirement because energy is not
• 44:30
  Speaker 1: even necessarily well defined at the quantum level.
• 44:33
  Speaker 3: I wonder if that means that some of the other
• 44:35
  Speaker 3: places that we've seen energy conservation being violated, like the
• 44:38
  Speaker 3: expansion of the universe. I wonder if that can mean that,
• 44:41
  Speaker 3: you know, as our universe expands and gains energy, maybe
• 44:43
  Speaker 3: there's another universe out there losing energy and being compressed.
• 44:48
  Speaker 1: It's a great question and one of the reasons I
• 44:49
  Speaker 1: really like this question zooming down to the microscopic scale
• 44:52
  Speaker 1: and trying to understand what is conservation of energy there
• 44:56
  Speaker 1: is because we're really interested in what it means at
• 44:58
  Speaker 1: our scale, Like where does energy come from? Why is
• 45:00
  Speaker 1: it conserved for us? Is it because it's required at
• 45:03
  Speaker 1: the quantum level, or is it because it emerges somehow?
• 45:06
  Speaker 1: And so yeah, maybe energy non conservation in general relativity
• 45:10
  Speaker 1: could eventually be derived from some deep quantum gravity, some
• 45:15
  Speaker 1: explanation of the nature of space time at the quantum
• 45:17
  Speaker 1: level that has these consequences at our scale or at
• 45:21
  Speaker 1: the scale of the whole universe. So that would be
• 45:23
  Speaker 1: really fascinating.
• 45:24
  Speaker 3: Yeah, or maybe vice versa, right, Like, if you prove
• 45:26
  Speaker 3: energy conservation at the grand level, it must might have
• 45:30
  Speaker 3: some consequences about you know, what we think is happening
• 45:33
  Speaker 3: at the quantum level.
• 45:34
  Speaker 1: It could be although sometimes conservation laws cannot be exact.
• 45:37
  Speaker 1: They can just emerge, so they don't have to always
• 45:39
  Speaker 1: hold true at the quantum level to hold true at
• 45:42
  Speaker 1: the classical level. But there are some things that are
• 45:44
  Speaker 1: truet the quantum level, Like we think conservation momentum is
• 45:47
  Speaker 1: rock solid at the quantum level, and the reason we
• 45:49
  Speaker 1: have it at our level is because everything is made
• 45:52
  Speaker 1: out of these quantum bits which follow these rules. So
• 45:55
  Speaker 1: we don't know basically whether conservation of energy is exact
• 45:58
  Speaker 1: the way conservation momentum is because it comes out of
• 46:01
  Speaker 1: the quantum level, or if it's something that emerges somehow
• 46:04
  Speaker 1: when you get classical physics.
• 46:06
  Speaker 3: I guess maybe your people in a pool experiment is
• 46:08
  Speaker 3: going to conclusively prove that.
• 46:10
  Speaker 1: Then give me one hundred years. It's going to take
• 46:13
  Speaker 1: a lot of data.
• 46:15
  Speaker 3: What do you Why do you need five years to
• 46:17
  Speaker 3: do this?
• 46:19
  Speaker 1: Oh man, because the I RB you know, you're doing
• 46:22
  Speaker 1: experiments on people. You got to sign the papers. It's
• 46:25
  Speaker 1: the whole thing.
• 46:27
  Speaker 3: I see. Yeah, And then there's a pool, so the
• 46:29
  Speaker 3: forms get wet. It's all a big mess. What does
• 46:32
  Speaker 3: this have more implications for our understanding of quantum mechanics
• 46:35
  Speaker 3: or understanding of energy conservation in the universe.
• 46:38
  Speaker 1: I think it has consequences for our understanding of what
• 46:41
  Speaker 1: energy is. As we drill down to see what the
• 46:44
  Speaker 1: universe really is like at the microscopic scale, we learn
• 46:47
  Speaker 1: about things that turn out to just be features of
• 46:50
  Speaker 1: our existence. They're not generally true at every level of
• 46:53
  Speaker 1: the universe, you know, like there's no equivalent to ice
• 46:56
  Speaker 1: cream at the quantum level, for example, there's no equivalent
• 46:59
  Speaker 1: to cats. Those things only exist at our level. And
• 47:02
  Speaker 1: so I love that as we keep looking deeper into
• 47:04
  Speaker 1: the universe, we discover things about our experience that turn
• 47:07
  Speaker 1: out to just be part of our experience. They're not
• 47:09
  Speaker 1: generally true about the universe, Like our sun is unusual,
• 47:13
  Speaker 1: and maybe our planet is weird, maybe our way of
• 47:16
  Speaker 1: life is weird. And the same way, we discover that
• 47:19
  Speaker 1: the way we experience the universe and the things we
• 47:21
  Speaker 1: think are fundamental about it actually aren't. To me, that's
• 47:24
  Speaker 1: really cool and opens up questions about like other conservation
• 47:27
  Speaker 1: laws are other things that we thought were hard and
• 47:30
  Speaker 1: fast and true about the universe actually just sort of
• 47:32
  Speaker 1: like emergent approximate things, and at a quantum level they're
• 47:36
  Speaker 1: not preserved. That would be kind of scary.
• 47:38
  Speaker 3: Well for me, I'm getting the sense that maybe, like
• 47:40
  Speaker 3: even if we do discover that energy is conserved or
• 47:43
  Speaker 3: not in our universe, that wouldn't maybe really tells what
• 47:47
  Speaker 3: the real truth is because we wouldn't have access to
• 47:49
  Speaker 3: maybe the multiverse in other universes, which would maybe cancel
• 47:54
  Speaker 3: out what we think is the rule of the universe.
• 47:56
  Speaker 1: Yeah, that's right. We could see what we think is
• 47:58
  Speaker 1: energy non conservation and bigger picture, it all balances out,
• 48:02
  Speaker 1: and so we might never really know these answers.
• 48:04
  Speaker 3: Well, I'll just take comfort in the fact that even
• 48:06
  Speaker 3: if I don't exercise today, maybe there's a quantum Woorge
• 48:10
  Speaker 3: in another universe who is doing double the exercise for
• 48:14
  Speaker 3: the tour that both us and in some way you
• 48:16
  Speaker 3: can say that I exercised today.
• 48:18
  Speaker 1: Yeah, that's true, and that quantum Hohoge will live longer
• 48:21
  Speaker 1: than you and on average, you know, some fractionales across
• 48:24
  Speaker 1: the teams, this will be alive or not.
• 48:27
  Speaker 3: Yeah, there you go. There you go, playing with some
• 48:29
  Speaker 3: kittens and counting people in a swimming pool. All right, Well,
• 48:33
  Speaker 3: we hope you enjoyed that. Thanks for joining us. See
• 48:37
  Speaker 3: you next time.
• 48:42
  Speaker 1: For more science and curiosity, come find us on social
• 48:45
  Speaker 1: media where we answer questions and post videos. We're on Twitter,
• 48:49
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• 48:53
  Speaker 1: and Jorge explain the universe is a production of iHeartRadio.
• 48:56
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• 49:00
  Speaker 1: Apple Apple Podcasts, or wherever you listen to your favorite shows.