Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions 43: Light, heat and vision

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Listener Questions 43: Light, heat and vision · Daniel and Kelly’s Extraordinary Universe

• 0:08
  Speaker 1: Hey, in this current heat wave, is South Pasadena feeling
• 0:12
  Speaker 1: hot or not?
• 0:14
  Speaker 2: You mean the temperature, the housing market, or the people.
• 0:17
  Speaker 1: Oh, I'm endlessly curious. I want to know about all
• 0:19
  Speaker 1: of it.
• 0:20
  Speaker 2: It's hot in all accounts. House prices are through the roof,
• 0:26
  Speaker 2: temperature is really hot, and the people I think are
• 0:28
  Speaker 2: pretty hot.
• 0:29
  Speaker 1: Are you guys like in danger of melting into a
• 0:31
  Speaker 1: puddle of hotness?
• 0:32
  Speaker 2: Yeah, it's like a big volcano out here.
• 0:34
  Speaker 1: So where is the epicenter? From? Where is all this
• 0:37
  Speaker 1: hotness flowing?
• 0:37
  Speaker 2: I'm not giving you my home address, man, it's too hot. Hi.
• 0:55
  Speaker 2: I'm horham and cartoonist and the author of Oliver's Great
• 0:58
  Speaker 2: Big Universe.
• 0:59
  Speaker 1: Hi, I'm Daniel. I'm a particle physicist and a professor
• 1:02
  Speaker 1: at UC Irvine, and I totally dig the heat.
• 1:06
  Speaker 2: You like the heat?
• 1:07
  Speaker 1: Oh? Absolutely, I'm a desert person. Heat and dry air
• 1:11
  Speaker 1: is my jam. You and lizards, Me and lizards, exactly. Lizards, Snow,
• 1:16
  Speaker 1: what's up? Man? You don't see lizards in Chicago in
• 1:20
  Speaker 1: the winter for a reason. It's miserable.
• 1:22
  Speaker 2: Well, maybe they just don't like deep dish pizza.
• 1:24
  Speaker 1: I'm pretty sure there were no lizards in Chicago like
• 1:26
  Speaker 1: five hundred years ago, before pizza was even invented.
• 1:30
  Speaker 2: I'm pretty sure there were dinosaurs in Chicago five hundred
• 1:33
  Speaker 2: million years ago.
• 1:34
  Speaker 1: But you know, it's not miserable for people who love
• 1:37
  Speaker 1: the snow, and I'm just not one of those people.
• 1:39
  Speaker 2: Your snow snow fan, It's a slippery subject. Ooh, an
• 1:43
  Speaker 2: icy reception there from Daniel Whitson. But anyways, welcome for
• 1:46
  Speaker 2: our podcast, Daniel and Jorge Explain the Universe, a production
• 1:50
  Speaker 2: of iHeartRadio.
• 1:51
  Speaker 1: In which we treat the universe with a warm heart
• 1:53
  Speaker 1: and an open mind. We try to soak up all
• 1:56
  Speaker 1: of the information that's coming to us from the distant
• 1:59
  Speaker 1: cosmos and from our nearby star to get an understanding
• 2:03
  Speaker 1: of how everything works, to tell ourselves a mathematical story
• 2:06
  Speaker 1: about how the universe clicks together and operates to make
• 2:10
  Speaker 1: this incredible cosmos that we live in.
• 2:13
  Speaker 2: That's right, because it is a pretty hot universe, full
• 2:15
  Speaker 2: of things going on, things moving about, and a lot
• 2:18
  Speaker 2: of attractive forces going on and repulsive I guess at
• 2:21
  Speaker 2: the same time.
• 2:22
  Speaker 1: I guess hot is pretty relative, though, I mean compared
• 2:24
  Speaker 1: to the history of the universe. We're basically at its
• 2:26
  Speaker 1: coldest moment.
• 2:28
  Speaker 2: Ever, isn't the universe going to get colder?
• 2:30
  Speaker 1: Well, it's the coldest moment so far. Absolutely. The universe
• 2:33
  Speaker 1: just keeps cooling and cooling as it expands, So every
• 2:36
  Speaker 1: moment is the coldest moment we've ever had.
• 2:39
  Speaker 2: But it also means it's hot, the hottest or as
• 2:43
  Speaker 2: pretty hot compared to how cold it's going to get.
• 2:46
  Speaker 1: That's right, We're all getting less and less hot as
• 2:48
  Speaker 1: time goes on.
• 2:49
  Speaker 2: I don't know about all of us. I think I'm
• 2:51
  Speaker 2: aging pretty well.
• 2:52
  Speaker 1: I and Harrison Ford are violating thermodynamics.
• 2:54
  Speaker 2: That's right, that's right, Unlike I guess Keanu Reeves, who's
• 2:57
  Speaker 2: not aging at all.
• 3:00
  Speaker 1: I thought you were about to say he's aging badly.
• 3:02
  Speaker 1: I was holding my breast there.
• 3:03
  Speaker 2: Who No, No, I think the whole universe agrees. Ken
• 3:06
  Speaker 2: Reeves is not aging.
• 3:09
  Speaker 1: He's frozen in time.
• 3:10
  Speaker 2: Somehow, that's true, somehow valiating the loosohis me. He's a
• 3:13
  Speaker 2: lizard too.
• 3:15
  Speaker 1: Let's get him on the podcast and ask his opinion
• 3:17
  Speaker 1: of deep dish pizza.
• 3:19
  Speaker 2: Yeah, well, place a call, especially after we call the lizard.
• 3:22
  Speaker 2: But it is a pretty interesting universe, full of all
• 3:25
  Speaker 2: kinds of things going on, and all kinds of questions
• 3:27
  Speaker 2: to ask about it, which is the job of scientists
• 3:29
  Speaker 2: and also the public and everyday people.
• 3:32
  Speaker 1: It's just part of being human to be curious about
• 3:35
  Speaker 1: the nature of the world we live in. You can't
• 3:37
  Speaker 1: help but ask yourself questions. When you see something, how
• 3:40
  Speaker 1: does that work? How does that connect with this other
• 3:43
  Speaker 1: idea I have? If the universe is microscopically, all these
• 3:45
  Speaker 1: tiny wizzing particles, how does that all come together to
• 3:48
  Speaker 1: make this rock feel hot to me? Right now? There's
• 3:51
  Speaker 1: so many questions we can ask about the nature of
• 3:53
  Speaker 1: the universe, and we want you to ask them because
• 3:56
  Speaker 1: it's a deep part of the joy of being human,
• 3:58
  Speaker 1: and also it literally fuels all of our science. If
• 4:02
  Speaker 1: humanity stop being curious about science, we wouldn't get to
• 4:05
  Speaker 1: do it anymore. So please keep asking questions, or.
• 4:08
  Speaker 2: At least keep funding scientists to ask questions professionally. But yeah,
• 4:12
  Speaker 2: everyone can ask questions.
• 4:13
  Speaker 1: Though everyone can, everyone should, and everyone does ask questions,
• 4:17
  Speaker 1: And on this podcast we encourage you to send us
• 4:19
  Speaker 1: your questions. If you're curious about something you don't understand,
• 4:23
  Speaker 1: please write to us two questions at Danielandjorge dot com.
• 4:27
  Speaker 1: We write back to everybody. We answer everybody's questions, even
• 4:30
  Speaker 1: if it takes one reply or a whole series of emails.
• 4:33
  Speaker 2: That's right. The questions you stand in, we'll get an answer,
• 4:36
  Speaker 2: and sometimes we pick them to be on the podcast
• 4:39
  Speaker 2: because they're so interesting that we think that everyone would
• 4:42
  Speaker 2: be interesting knowing the answered.
• 4:44
  Speaker 1: That's right. And so from the daily on slot of
• 4:47
  Speaker 1: emails froom listeners, I've picked a new batch of questions
• 4:50
  Speaker 1: for us to answer.
• 4:51
  Speaker 2: So to the on the podcast, we'll be tackling listener
• 4:58
  Speaker 2: questions number forty three light Vision and Heat. That sounds
• 5:03
  Speaker 2: like the like an album title. Daniel and Jorra explains
• 5:07
  Speaker 2: the universe, the sound and the fury, Light Vision and Heat.
• 5:10
  Speaker 1: It sounds like our eighties electronic album. Yeah, there you go,
• 5:13
  Speaker 1: pull out that synthesizer. Man, well, or we can just
• 5:15
  Speaker 1: beatbox it. I guess how's your singing voice. I got
• 5:19
  Speaker 1: a baritone. It's out of tune, but I got a baritone.
• 5:22
  Speaker 2: I'll just do the do do Do, Do Do Do.
• 5:24
  Speaker 2: But yeah, we got some awesome questions here today about
• 5:27
  Speaker 2: light vision and heat, about what kinds of particles humans
• 5:31
  Speaker 2: can and might be able to see in the future,
• 5:34
  Speaker 2: about how to vaporize liquid water, and about the spectrum
• 5:38
  Speaker 2: of light. So let's dig into it. Our first question
• 5:41
  Speaker 2: comes from Milo, who's six years old.
• 5:43
  Speaker 3: Hey, guys, I have a question. Could be evolve to
• 5:49
  Speaker 3: see other particles besides photons, like neutrons, produds, and a
• 5:58
  Speaker 3: whole bunch more.
• 6:00
  Speaker 2: Awesome question from a six year old. That's amazing. There's
• 6:03
  Speaker 2: like so many science concepts in that one question. I
• 6:06
  Speaker 2: feel like there's a whole high school curriculum there.
• 6:09
  Speaker 1: Milo is amazing. Wow. I don't think I knew about neutrons, protons,
• 6:13
  Speaker 1: and a whole bunch more when I was six years old.
• 6:17
  Speaker 2: I don't think I was pondering the evolution of human
• 6:20
  Speaker 2: sensory organs at six years old.
• 6:23
  Speaker 1: I felt like neutrons, protons, and a whole bunch more
• 6:25
  Speaker 1: should be like a breakfast cereal that Milo invents.
• 6:27
  Speaker 2: Neutrino's already sounds like a breakfast cereal.
• 6:30
  Speaker 1: Name neutrinos, Like, do you take your neutrinos with milk?
• 6:34
  Speaker 2: Yeah? Yeah, Well I'm kind of neutral to it. Oat milk,
• 6:37
  Speaker 2: soy milk? You all charge to say?
• 6:39
  Speaker 1: It seems like something you need is just a tiny
• 6:41
  Speaker 1: little sip of right, Nobody has a big bowl of neutrinos,
• 6:44
  Speaker 1: just like a little espresso shot of neutrinos to start
• 6:47
  Speaker 1: your day.
• 6:49
  Speaker 2: It depends on your diet, I guess. But yeah, it's
• 6:51
  Speaker 2: an interesting question, and let's break it down here. So
• 6:54
  Speaker 2: Milo wants to know could people evolve to see other
• 6:56
  Speaker 2: particles besides photons? Other particles like neutrons, protons, and a
• 7:01
  Speaker 2: bunch more.
• 7:02
  Speaker 1: Yeah, it's a really cool question. And he starts with seeing, right,
• 7:05
  Speaker 1: can we see other particles besides photons? And he's right
• 7:09
  Speaker 1: that technically what we're seeing are photons. Like when you
• 7:12
  Speaker 1: look out at the view in front of you, you're
• 7:14
  Speaker 1: getting light bounced off of the rocks and the trees
• 7:17
  Speaker 1: and the grass and the water. Different wavelengths are coming
• 7:19
  Speaker 1: and hitting your eyes and making up that vision that
• 7:22
  Speaker 1: you see. So when you see, it's the photons around
• 7:25
  Speaker 1: you that you are most directly seeing.
• 7:27
  Speaker 2: Yeah, and how does that work? I guess The photon
• 7:29
  Speaker 2: enters your eye and it hits the H receptor cones
• 7:33
  Speaker 2: in the back of your eye, and then that creates
• 7:35
  Speaker 2: a brain signal.
• 7:36
  Speaker 1: Yeah, there are these amazing proteins inside the rods and
• 7:39
  Speaker 1: cones of your eyeball which respond to various frequencies of light,
• 7:43
  Speaker 1: Like flip a switch, they change their configuration and that
• 7:46
  Speaker 1: generates a signal which goes down the optic nerve and
• 7:49
  Speaker 1: then your brain interprets it as a certain color or
• 7:52
  Speaker 1: brightness or darkness. And we did a fun podcast episode
• 7:55
  Speaker 1: about like the amazing ability of the human eye to
• 7:58
  Speaker 1: see a single individ jewel photon. There are these incredible
• 8:01
  Speaker 1: experiments they did. We verified that the human eye can
• 8:04
  Speaker 1: detect a single photon at a time.
• 8:07
  Speaker 2: Yeah, it's pretty amazing, But I guess those only respond
• 8:09
  Speaker 2: to photons, right, which is light, Like if you shoot
• 8:13
  Speaker 2: it with another kind of particle, would it create Is
• 8:15
  Speaker 2: it possible that it can create a signal that you
• 8:17
  Speaker 2: might detect.
• 8:18
  Speaker 1: So probably not. If one of those proteins got hit
• 8:20
  Speaker 1: by a proton or a neutron or something, it wouldn't
• 8:23
  Speaker 1: react the same way and give you that signal. But
• 8:27
  Speaker 1: remember that those rods and cones are embedded kind of
• 8:30
  Speaker 1: deep in your eye. You have to get all the
• 8:31
  Speaker 1: way through like the lens and the fluid and all
• 8:33
  Speaker 1: that stuff to the back of the eyeball. So if
• 8:35
  Speaker 1: a proton hit those rods and cones directly, you probably
• 8:37
  Speaker 1: wouldn't see it. But another question is what would happen
• 8:40
  Speaker 1: if you shot a single proton or neutron into your eyeball?
• 8:44
  Speaker 1: Would you then see it? And the answer to that
• 8:46
  Speaker 1: is probably yes. What what do you mean, Well, a
• 8:49
  Speaker 1: proton and a neutron will not just pass through your eyeball.
• 8:52
  Speaker 1: It will interact when the material in your eyeball. Protons
• 8:55
  Speaker 1: and neutrons are made out of quarks. The stuff in
• 8:57
  Speaker 1: your eyeball is made out of quarks. So protons and
• 8:59
  Speaker 1: newton will not just pass through your eyeball. It's like
• 9:02
  Speaker 1: throwing a tennis ball at a rock wall, right, It's
• 9:05
  Speaker 1: either going to bounce off or it's going to smash through.
• 9:07
  Speaker 1: And when it smashes through, it's going to break open
• 9:10
  Speaker 1: those particles, and it's going to create all sorts of
• 9:12
  Speaker 1: showers of particles, including photons.
• 9:16
  Speaker 2: So you might see like a flash of light as
• 9:18
  Speaker 2: a proton enters your eye, maybe hit some of the
• 9:22
  Speaker 2: water inside of your eyeball, and then it creates like
• 9:24
  Speaker 2: a little light spark exactly.
• 9:26
  Speaker 1: And so you can argue about whether you're technically seeing
• 9:29
  Speaker 1: the proton because the rods and cones themselves are not
• 9:32
  Speaker 1: interacting with the proton, but the proton is causing a
• 9:35
  Speaker 1: shower of particles, some of which are photons, And that's
• 9:39
  Speaker 1: actually how we see protons. Like at the large hadron collider,
• 9:42
  Speaker 1: you create a proton and the collision you don't see
• 9:44
  Speaker 1: the proton directly smashes into these layers of steel or
• 9:47
  Speaker 1: depleted uranium and then creates showers of particles which we
• 9:51
  Speaker 1: then can see mostly the photons that are created.
• 9:54
  Speaker 2: MM. So you have like a little particle collider in
• 9:57
  Speaker 2: your eye, large eye collider.
• 10:00
  Speaker 1: I'm not recommending anybody shoot protons at their eyeball, but
• 10:03
  Speaker 1: I'm saying if it did happen, you probably would see
• 10:06
  Speaker 1: a flash if there's high enough energy. If you just
• 10:09
  Speaker 1: like very gently throw a proton at your eyeball, it'll
• 10:12
  Speaker 1: just bounce off the same way like a tennis ball
• 10:14
  Speaker 1: will bounce off of a wall. But a bullet shooting
• 10:16
  Speaker 1: really hard will penetrate in. And so it just depends
• 10:19
  Speaker 1: on the energy of the proton, you.
• 10:21
  Speaker 2: Mean, like the speed of it, Like it has to
• 10:23
  Speaker 2: be going fast enough for you to maybe be able
• 10:25
  Speaker 2: to see a proton or neutron exactly.
• 10:27
  Speaker 1: If it's going really slow, it's just going to bounce off,
• 10:29
  Speaker 1: and the same is true of a neutron. A neutron
• 10:31
  Speaker 1: is also a little bag of quarks. If you shoot
• 10:33
  Speaker 1: in a very high energy at your eyeball, it'll create
• 10:35
  Speaker 1: little flashes of light inside your eyeball and you'll see them.
• 10:38
  Speaker 2: But it's also I think not good, right, if you
• 10:42
  Speaker 2: shoot a bunch of protons into your eye's gonna kill
• 10:46
  Speaker 2: your eyes, isn't it.
• 10:47
  Speaker 1: Yeah, these are mini bullets, right, You're shooting tiny bullets
• 10:50
  Speaker 1: at eyeballs. Not something we recommend. I mean I'm answering
• 10:53
  Speaker 1: the question, would you see it? The answer is yes,
• 10:55
  Speaker 1: not should you do it? Bad? Answer is definitely no.
• 10:58
  Speaker 1: Do not do this experiment.
• 10:59
  Speaker 2: Like, for example, when astronauts are out there in space
• 11:02
  Speaker 2: in your orbit, I mean, they need a lot of
• 11:03
  Speaker 2: shielding in the space station just because of things like
• 11:06
  Speaker 2: protons and neutrons raining down on them, right, Like, those
• 11:09
  Speaker 2: are not good to be hit with.
• 11:11
  Speaker 1: Yeah, exactly. Cosmic rays are nothing but high energy particles
• 11:14
  Speaker 1: in space, usually produced by the Sun or from other stars,
• 11:18
  Speaker 1: et cetera. Those are high energy electrons or protons, et cetera.
• 11:22
  Speaker 1: And yeah, you don't want to get hit by those.
• 11:23
  Speaker 1: Those are tiny bullets. And they can pass through your
• 11:25
  Speaker 1: body and cause all sorts of damage. They can wreck
• 11:28
  Speaker 1: your DNA, they can deposit energy, all sorts of stuff.
• 11:31
  Speaker 1: And that's true any particle that has the strong force,
• 11:33
  Speaker 1: meaning it's made of quarks, or any particle that has electromagnetism. Right,
• 11:37
  Speaker 1: you're shoot an electron at your eyeball, the same kind
• 11:40
  Speaker 1: of stuff is going to happen. It's going to generate
• 11:42
  Speaker 1: photons as it interacts with your eyeball, and that's true
• 11:44
  Speaker 1: of basically any particle we know about except neutrinos.
• 11:48
  Speaker 2: Well, wait, electrons. Electrons might possibly activate one of your
• 11:51
  Speaker 2: eye sensors, right, eyrods or cones, couldn't they because they
• 11:54
  Speaker 2: sort of work electrically.
• 11:57
  Speaker 1: Yeah, it's going to be one step removed because the
• 11:59
  Speaker 1: way an electron would interact with it is by emitting
• 12:01
  Speaker 1: a photon and so to the photon more directly that
• 12:04
  Speaker 1: you're seeing. And when an electron enters a medium like that,
• 12:08
  Speaker 1: it slows down or changes direction, and to do so,
• 12:10
  Speaker 1: it emits photons. So electrons will also create showers of
• 12:13
  Speaker 1: photons when they hit something, and that again happens at
• 12:16
  Speaker 1: particle colliders. We produce very high energy electrons, and they
• 12:20
  Speaker 1: create these showers of photons, which then produce more electrons,
• 12:23
  Speaker 1: which produce more photons. And you start out with like
• 12:25
  Speaker 1: one high energy particle, you end up with like a
• 12:28
  Speaker 1: billion lower energy photons.
• 12:30
  Speaker 2: But could an electron maybe make it all the way
• 12:32
  Speaker 2: to the back of your eye and hit one of
• 12:34
  Speaker 2: your eye sensors and then flip the switch.
• 12:36
  Speaker 1: An electron could make it all the way back to
• 12:38
  Speaker 1: your eye and hit one of those proteins. But those
• 12:40
  Speaker 1: proteins are very sensitive, right, They're designed to respond only
• 12:43
  Speaker 1: to certain frequencies of light, which is how you can
• 12:46
  Speaker 1: tell the difference between green and red and blue because
• 12:49
  Speaker 1: some sensors have flipped and other sensors have not flipped.
• 12:51
  Speaker 1: So a random electron banging into it, I don't know
• 12:54
  Speaker 1: what's going to happen. It's sort of like asking, like,
• 12:55
  Speaker 1: what poem would you type if you randomly mashed them
• 12:58
  Speaker 1: the keyboard, Like, I don't know.
• 13:00
  Speaker 2: And we can see electron poetry. That's what I got from.
• 13:06
  Speaker 1: Now.
• 13:06
  Speaker 2: I'm just kidding you saying you might see an occasional
• 13:09
  Speaker 2: electron directly, but it's not likely.
• 13:12
  Speaker 1: Maybe, yeah, mostly you would see an electron if it
• 13:15
  Speaker 1: creates photons in your eyeball, which it would if it's
• 13:17
  Speaker 1: moving at high speed through the medium of your eyeball,
• 13:20
  Speaker 1: it will be creating photons as it interacts with atomic
• 13:23
  Speaker 1: electrons and atomic nuclei.
• 13:25
  Speaker 2: All right, now, what about my list question a second
• 13:27
  Speaker 2: part of the question which asked about a bunch of
• 13:29
  Speaker 2: more particles, but about all the other particles.
• 13:32
  Speaker 1: Yeah, so the other particles are ones that don't have
• 13:34
  Speaker 1: electromagnetic or strong interactions, and so far that list is
• 13:38
  Speaker 1: just neutrinos, so it might also include dark matter eventually. Right, So,
• 13:43
  Speaker 1: like you can ask, could we evolve to detect neutrinos? Well,
• 13:47
  Speaker 1: in principle, it is possible to detect neutrinos. It's just
• 13:50
  Speaker 1: that neutrinos are very very hard to detect. There's lots
• 13:53
  Speaker 1: of them all over the place, but they interact very
• 13:56
  Speaker 1: very rarely. So, for example, in order to detect the
• 14:00
  Speaker 1: existence of neutrinos in the first place, they had to
• 14:03
  Speaker 1: set up these instruments that have like one hundred thousand
• 14:06
  Speaker 1: gallons of special fluid just to detect a few neutrinos
• 14:10
  Speaker 1: a week. When there's like trillions and trillions of them
• 14:13
  Speaker 1: passing through. That means that the physics is there for
• 14:15
  Speaker 1: materials to interact with neutrinos, which means you could evolve
• 14:18
  Speaker 1: a body part to do it, but it would have
• 14:21
  Speaker 1: to be enormous.
• 14:22
  Speaker 2: Well, what happens when I feel like your eyeball is
• 14:25
  Speaker 2: sort of like one of these water detectors, right, like
• 14:28
  Speaker 2: liquid detectors, right, I mean it is technically possible for
• 14:31
  Speaker 2: a neutrino, because we're getting showered with them by the
• 14:34
  Speaker 2: billions trillions, it is possible for one of them to
• 14:37
  Speaker 2: interact with the maybe a water molecule inside your eye
• 14:40
  Speaker 2: and generate some photons, right, But.
• 14:42
  Speaker 1: Yeah, it's totally possible in that sense. Yes, your eyeball
• 14:45
  Speaker 1: can see neutrinos indirectly the same way you can see electrons.
• 14:48
  Speaker 1: Like a neutrino passing through your eyeball could give an
• 14:52
  Speaker 1: electron a little kick, and that electron could then generate
• 14:55
  Speaker 1: some photons, or give an atomic nucleus a kick and
• 14:58
  Speaker 1: break it apart, or that nucleus could viberate and rotate
• 15:00
  Speaker 1: and then emit a photon. So yeah, indirectly, neutrinos can
• 15:04
  Speaker 1: deposit their energy inside the stuff in your eyeball and
• 15:07
  Speaker 1: then you could see it. It's just that it's much
• 15:10
  Speaker 1: less likely. Like you shoot an electron at your eyeball,
• 15:13
  Speaker 1: you're almost definitely going to see every individual single electron.
• 15:16
  Speaker 1: You shoot a neutrino at your eyeball, you have like
• 15:19
  Speaker 1: a one in a gazillion chance of seeing it.
• 15:21
  Speaker 2: Mm, So you can detake neutrino's, just not all of them,
• 15:25
  Speaker 2: I guess, Or it's very unlikely for you to detect
• 15:28
  Speaker 2: the neutrino.
• 15:29
  Speaker 1: Yeah, if you wanted to, like use neutrino vision, if
• 15:31
  Speaker 1: you wanted to have a reliable neutrino sense, you'd have
• 15:34
  Speaker 1: to evolve some kind of eyeball that was either very
• 15:37
  Speaker 1: very very large, you know, we're talking like swimming pool
• 15:41
  Speaker 1: size tanks of liquid, or very very very dense, so
• 15:45
  Speaker 1: the neutrino's had a harder time getting through. It seems
• 15:47
  Speaker 1: pretty impractical unless you know you're enormous.
• 15:50
  Speaker 2: Or maybe you just don't need to detect all of them, right,
• 15:53
  Speaker 2: like night vision.
• 15:54
  Speaker 1: Well, I think in the case of night vision, you
• 15:55
  Speaker 1: are detecting those photons. You're super sensitive to individual ones
• 15:59
  Speaker 1: because they're so rare. But you're right, we don't need
• 16:01
  Speaker 1: to necessarily detect all of them. I guess it depends
• 16:03
  Speaker 1: on what you want to do, Like what are neutrinos
• 16:05
  Speaker 1: useful for? What can you know about the universe if
• 16:07
  Speaker 1: you could see neutrinos.
• 16:09
  Speaker 2: That's an interesting question. What would happen if you could,
• 16:11
  Speaker 2: would you have like X ray vision kind.
• 16:13
  Speaker 1: Of Well, you know, if you could see neutrinos, then
• 16:17
  Speaker 1: you could see the Sun during the nighttime because you
• 16:20
  Speaker 1: could look through the Earth and see the neutrinos because
• 16:23
  Speaker 1: they pass almost entirely unscathed through the Earth. And people
• 16:27
  Speaker 1: have done this, They've built neutrino telescopes and point to
• 16:29
  Speaker 1: them at the Earth at nighttime and you can see
• 16:31
  Speaker 1: the Sun. So you can like verify the sun is
• 16:33
  Speaker 1: still there during nighttime. If that's the kind of thing
• 16:36
  Speaker 1: you worry about, well.
• 16:38
  Speaker 2: Like the sun would be underneath your feet.
• 16:40
  Speaker 1: Yeah, so I guess in principle you could prove that
• 16:42
  Speaker 1: the sun will rise tomorrow. If you had neutrino eyebolves.
• 16:46
  Speaker 2: You could predict when the sun will rise.
• 16:49
  Speaker 1: Well.
• 16:49
  Speaker 2: I feel like that's a big part of Milo's question,
• 16:51
  Speaker 2: which is like could people evolve to see these particles?
• 16:54
  Speaker 2: To evolve something, it has to be kind of useful
• 16:57
  Speaker 2: to evolution, right to the species otherwise life wouldn't bother
• 17:01
  Speaker 2: getting that.
• 17:01
  Speaker 1: Ability exactly, and developing new bits costs energy, and so
• 17:05
  Speaker 1: it has to have some sort of benefit. It's interesting
• 17:08
  Speaker 1: to think about that, though, because I think that life
• 17:10
  Speaker 1: on Earth existed for hundreds of millions of years before
• 17:14
  Speaker 1: any of it was photosensitive. Right, we'd be like bathed
• 17:17
  Speaker 1: in photons and totally blind to them. Where I'm talking
• 17:20
  Speaker 1: about our microbial ancestors before anybody evolved it. In the
• 17:24
  Speaker 1: same way that like, there was no ability to hear
• 17:26
  Speaker 1: sounds for hundreds of millions of years before hearing evolved,
• 17:30
  Speaker 1: So it could take a long time even for things
• 17:32
  Speaker 1: that seem obvious and have huge benefits. In the case
• 17:35
  Speaker 1: of neutrinos like p I can't hardly even think of
• 17:38
  Speaker 1: a benefit. Like it's not going to help you find
• 17:40
  Speaker 1: food or evade hunters. Maybe you could help you, like
• 17:43
  Speaker 1: see through a mountain to see if there are caves
• 17:45
  Speaker 1: in there where you could like build a home. I'm
• 17:47
  Speaker 1: really reaching for the application of neutrino eyeballs.
• 17:51
  Speaker 2: Well, it sounds like having X ray vision would be useful, right,
• 17:54
  Speaker 2: like if there's a predator hiding behind a tree or something.
• 17:56
  Speaker 1: Yeah, but you're going to see right through the predator
• 17:58
  Speaker 1: and through the tree.
• 17:59
  Speaker 2: But you would see maybe a hint of the predator
• 18:02
  Speaker 2: behind the tree, couldn't you sort of how X rays.
• 18:04
  Speaker 1: Work if the predator and the tree had like different
• 18:07
  Speaker 1: sensitivities to neutrinos, But both of them are going to
• 18:09
  Speaker 1: be like totally invisible to neutrinos, so you're not gonna
• 18:12
  Speaker 1: be able to see it. I mean, you could see
• 18:14
  Speaker 1: a predator if they were like generating neutrinos. Oh. You
• 18:16
  Speaker 1: know what you could do is you could detect nuclear
• 18:18
  Speaker 1: reactors all over the world, right because those generating neutrinos.
• 18:23
  Speaker 2: Oh, well, there you go.
• 18:24
  Speaker 1: You could detect atomic bombs going off that kind of stuff.
• 18:29
  Speaker 2: I'm not sure seeing it before it happens is going
• 18:32
  Speaker 2: to really help you once see if you're that close
• 18:34
  Speaker 2: to an atomic bomb.
• 18:36
  Speaker 1: Yeah, and atomic bombs not famously subtle anyway, So.
• 18:38
  Speaker 2: Yeah, yeah, you would see it and feel it in
• 18:41
  Speaker 2: other ways.
• 18:41
  Speaker 1: But it would be super cool and it's fascinating that
• 18:44
  Speaker 1: there is all this stuff going on in the universe
• 18:47
  Speaker 1: right around us that we don't have senses to it. I
• 18:49
  Speaker 1: feel like that's sort of what Milo is reaching for.
• 18:51
  Speaker 1: It's like he wants to know more about what's out
• 18:54
  Speaker 1: there in the universe. He wants to see more, he
• 18:55
  Speaker 1: wants to experience more of these things about the universe.
• 18:59
  Speaker 1: And I totally get that, Like I feel the same way.
• 19:01
  Speaker 1: I want to know what's out there. I feel like
• 19:03
  Speaker 1: we can only see this tiny slipper of what's really
• 19:06
  Speaker 1: happening in the universe.
• 19:07
  Speaker 2: Hmmm, that's like you need to evolve, Daniel.
• 19:10
  Speaker 1: It's either that or get frozen in time like Keanu
• 19:12
  Speaker 1: Reeves that can't decide.
• 19:13
  Speaker 2: Yeah, how do you know? Caneries can't see na tree is?
• 19:16
  Speaker 2: Maybe lizards can see the tree is?
• 19:18
  Speaker 1: His career is sort of like an atomic bomb. That's true.
• 19:21
  Speaker 2: Yeah, he keeps blowing up all right. Well, I think
• 19:23
  Speaker 2: that answers Mila's question. Could people evolve to see other
• 19:26
  Speaker 2: particles besides photons? The answer is yes, technically you could,
• 19:30
  Speaker 2: and you have sort of in a way you can
• 19:33
  Speaker 2: sense with your eyes. You can send particles like high
• 19:36
  Speaker 2: speed protons and neutrons and electrons. You can see those
• 19:40
  Speaker 2: with your eyeballs right now if they shoot into your eyes. Again,
• 19:43
  Speaker 2: not recommend it, but you can't do it, and you
• 19:45
  Speaker 2: can maybe even imagine evolving your eye in some way
• 19:48
  Speaker 2: that you are more sensitive to those things, right, yeah, absolutely,
• 19:52
  Speaker 2: all right, Well, thanks for the question, Mila. Let's get
• 19:55
  Speaker 2: to some of these other questions about vaporizing water and
• 19:58
  Speaker 2: also this spectrum of light. But first let's take a
• 20:02
  Speaker 2: quick break.
• 20:15
  Speaker 1: All right.
• 20:16
  Speaker 2: We're answering listener questions here today, and we have some
• 20:18
  Speaker 2: awesome questions about light, vision and heat. It's getting pretty
• 20:22
  Speaker 2: hard in here.
• 20:24
  Speaker 1: It's funny. I usually try to group these questions by topic,
• 20:26
  Speaker 1: but these just came in right one after another. There's
• 20:29
  Speaker 1: sort of people are just naturally thinking about these things
• 20:32
  Speaker 1: at the same time around the world or something.
• 20:34
  Speaker 2: It's a hard topic. All right. Well, let's get to
• 20:35
  Speaker 2: our next question, which comes from Mark from the UK.
• 20:39
  Speaker 4: Hi, Daniel and Jorge. My name is Mark and I'm
• 20:41
  Speaker 4: calling from London, UK. I have a hypothetical question for you.
• 20:45
  Speaker 4: Your mission, should you choose to accept it, is to
• 20:47
  Speaker 4: melt my one kilogram block of ice in the fastest
• 20:49
  Speaker 4: time possible. You can use any existing tools or technology,
• 20:53
  Speaker 4: but I'd like one kilogram of liquid water as a
• 20:55
  Speaker 4: result of your efforts. So how will you do it,
• 20:58
  Speaker 4: how long will it take you? And why can't it
• 21:00
  Speaker 4: be done any faster many thanks love the podcast.
• 21:03
  Speaker 2: All right, awesome question for Mark. I feel like he's
• 21:06
  Speaker 2: challenging us.
• 21:06
  Speaker 1: He is, exactly This sounds like more of a question
• 21:09
  Speaker 1: for engineers and physicists.
• 21:10
  Speaker 2: Hmmm. You mean people who can actually do it.
• 21:14
  Speaker 1: People who like have useful skills to solthy real world problems.
• 21:18
  Speaker 2: Yeah, I'm with you. I'm not arguing at all. We'll
• 21:21
  Speaker 2: have to ask that question at my other podcast, or
• 21:25
  Speaker 2: it fixes the universe with engineering.
• 21:28
  Speaker 1: Or he melts your ice there you go.
• 21:30
  Speaker 2: All right, Well, so the challenge for Mark is to
• 21:33
  Speaker 2: take a one kilogram block of ice and melt it
• 21:37
  Speaker 2: into liquid water, but just liquid I guess, not a
• 21:41
  Speaker 2: liquid water vapor in the fastest way possible. It's like
• 21:45
  Speaker 2: a race.
• 21:46
  Speaker 1: Yeah, it's a really interesting challenge. You know. The physics,
• 21:49
  Speaker 1: or I guess the chemistry underlying it, of course, is
• 21:52
  Speaker 1: that you need to get some energy into this ice, right,
• 21:55
  Speaker 1: You need to heat it up. You need to get
• 21:56
  Speaker 1: those molecules moving so they break those bonds and they
• 22:00
  Speaker 1: relax and change phases from solid into liquid. So it's
• 22:03
  Speaker 1: all about getting energy into this object as fast as possible.
• 22:07
  Speaker 2: Yeah, and the tricky thing is you want to lucify it,
• 22:10
  Speaker 2: not vaporize.
• 22:11
  Speaker 3: Yeah.
• 22:11
  Speaker 1: He started out saying melt, and then I was thinking, hmm, interesting,
• 22:14
  Speaker 1: we could just like zap that thing with energy. But
• 22:17
  Speaker 1: then he was very specific. He wants to cure hem
• 22:19
  Speaker 1: of liquid water, not steam. So you can't just like
• 22:23
  Speaker 1: blow up a nuclear bomb next to it because that's
• 22:25
  Speaker 1: going to vaporize it.
• 22:26
  Speaker 2: So he's thirsty, he doesn't want to son it.
• 22:31
  Speaker 1: Yeah, I don't know if he has an actual situation
• 22:33
  Speaker 1: where this will improve his life or if he's just
• 22:37
  Speaker 1: challenging us.
• 22:38
  Speaker 2: Usually people want to freeze water right where right now,
• 22:41
  Speaker 2: the problem is that the ice caps are melting, which
• 22:43
  Speaker 2: is the opposite problem.
• 22:45
  Speaker 1: Yeah, exactly, all.
• 22:46
  Speaker 2: Right, So you're saying a bomb would not work, Like
• 22:49
  Speaker 2: if I explode a bomb, a grenade, a nuclear bomb
• 22:52
  Speaker 2: next to a block of ice, that would definitely take
• 22:54
  Speaker 2: it away from being solid, but it would maybe take
• 22:57
  Speaker 2: it too far and with the vaporize.
• 22:59
  Speaker 1: Yeah, essentially overshoot, right, it would deposit an incredible amount
• 23:02
  Speaker 1: of energy, vaporize it into fraction of a second. But
• 23:06
  Speaker 1: it wouldn't be something we could then pass to Mark
• 23:08
  Speaker 1: and say here's your kilogram of liquid water. It would
• 23:10
  Speaker 1: not only be vaporized, it would be dispersed.
• 23:12
  Speaker 2: Wouldn't it just get blown away, like pushed out of
• 23:14
  Speaker 2: the way.
• 23:15
  Speaker 1: Oh would the block of ice survive.
• 23:17
  Speaker 2: Or parts of it? I don't know. I guess it
• 23:19
  Speaker 2: depends on how big of the bomb it is.
• 23:22
  Speaker 1: It depends on how big the bomb is and how
• 23:23
  Speaker 1: close you are to it. But it's definitely going to
• 23:26
  Speaker 1: be a fireball and it's going to be a huge
• 23:27
  Speaker 1: amount of energy right dumped into it.
• 23:31
  Speaker 2: It's uncontrolled.
• 23:32
  Speaker 1: Yeah, you're dumping an incredible amount of energy into the air,
• 23:35
  Speaker 1: and then that creates this shock wave which travels outwards.
• 23:39
  Speaker 1: So it probably would shatter the ice also and dump
• 23:42
  Speaker 1: energy into it.
• 23:42
  Speaker 2: All Right, so a bomb or something explodes. If wouldn't work,
• 23:46
  Speaker 2: can we use technology? Can we just take it into microwave?
• 23:49
  Speaker 1: Yeah? Microwave is a cool idea because it deposits energy. Right,
• 23:53
  Speaker 1: You take the energy, you create this radiation. That radiation
• 23:56
  Speaker 1: then gets absorbed by the material and then it heats
• 23:58
  Speaker 1: up and it's actually basically good ad heating up. Water
• 24:02
  Speaker 1: and molecules like water have these partial electric dipoles, meaning
• 24:05
  Speaker 1: that they're like more positively charged in one direction and
• 24:08
  Speaker 1: more necularly charge in the other direction, and these get
• 24:10
  Speaker 1: like spun around by the waves. The ways go back
• 24:13
  Speaker 1: and forth and the molecules spin back and forth. So
• 24:16
  Speaker 1: it's actually a very efficient way to heat up liquid water.
• 24:19
  Speaker 1: You have a toub of liquid water you put in
• 24:21
  Speaker 1: the microwave, it's very very efficient dump that energy into
• 24:24
  Speaker 1: the motion. The wiggling of those molecules heat it up. Unfortunately,
• 24:27
  Speaker 1: it doesn't work nearly as well for frozen water, which
• 24:31
  Speaker 1: is what we're starting with, because in frozen water, the
• 24:33
  Speaker 1: molecules can't wiggle, so you can't really get them moving.
• 24:36
  Speaker 1: And you might have noticed that you put something frozen
• 24:38
  Speaker 1: in the microwave, it takes a long time to defrost it.
• 24:40
  Speaker 2: Well, they do sort of wiggle, but they maybe wiggle
• 24:42
  Speaker 2: in place, or maybe they don't wiggle as much.
• 24:45
  Speaker 1: Yeah, exactly, they don't wiggle as effectively, which is why
• 24:48
  Speaker 1: it's more efficient to put energy into liquid water than
• 24:51
  Speaker 1: frozen water using a microwave. So, if your goal is
• 24:54
  Speaker 1: to take water from frozen to liquid, a microwave is
• 24:57
  Speaker 1: not a very efficient way to do it, but it
• 24:59
  Speaker 1: would work.
• 25:00
  Speaker 2: It's also kind of uncontrolled, right, like you might be
• 25:02
  Speaker 2: turning some of those water molecules into vapor, right, because
• 25:07
  Speaker 2: you're just shooting microwaves into it, You're not controlling which
• 25:10
  Speaker 2: water molecules get the energy.
• 25:11
  Speaker 1: Yeah, you're gonna get hot spots and cold spots, right,
• 25:14
  Speaker 1: and so some of it's going to vaporize and other
• 25:16
  Speaker 1: pieces are still going to be frozen exactly. Mark is
• 25:19
  Speaker 1: not going to be a happy customer.
• 25:20
  Speaker 2: All right, So what else can we do to liquefy
• 25:22
  Speaker 2: this block of ice?
• 25:23
  Speaker 1: So Mark says, we can use any existing technology. So
• 25:26
  Speaker 1: I was thinking, let's go basic. Let's like chop this
• 25:29
  Speaker 1: thing up, because our goal is to dump a bunch
• 25:31
  Speaker 1: of energy into it. And a challenge with the block
• 25:33
  Speaker 1: of ice is getting to the core of it. How
• 25:35
  Speaker 1: do you heat up the center of it? So I thought, well,
• 25:37
  Speaker 1: let's like take this block of ice and chop it
• 25:40
  Speaker 1: into a lot of tiny little pieces, and then we
• 25:41
  Speaker 1: can just melt those individual pieces by like pouring hot
• 25:44
  Speaker 1: water over them.
• 25:45
  Speaker 2: Wait, what, you can pour hot water into it?
• 25:48
  Speaker 1: Yeah, if you have an ice cube, you can just
• 25:49
  Speaker 1: pour hot water onto it and that will melt the
• 25:51
  Speaker 1: ice cube. Hmmmm.
• 25:53
  Speaker 2: So your strategy would be chop it up and then
• 25:56
  Speaker 2: dump it all into a not steaming but still hot
• 26:00
  Speaker 2: tub of.
• 26:00
  Speaker 1: Water exactly, And if you want it to melt even faster,
• 26:05
  Speaker 1: you can even pour a salt water on it, because
• 26:08
  Speaker 1: salt water melts at a lower temperature than distilled water.
• 26:12
  Speaker 1: I don't know that Mark really wants to drink a
• 26:14
  Speaker 1: kilogram of salt water, but that would melt faster.
• 26:17
  Speaker 2: Well, I don't know if he wants to drink a
• 26:18
  Speaker 2: whole tubful of salt water, that's your plan. I feel
• 26:21
  Speaker 2: like you've just multiplied as water, sort of like a
• 26:24
  Speaker 2: certain character from the Bible.
• 26:26
  Speaker 1: Another option is to sort of take advantage of the
• 26:28
  Speaker 1: weird chemistry of water. Water has this weird property that
• 26:33
  Speaker 1: ice takes up more volume than liquid water. Right when
• 26:36
  Speaker 1: you freeze it, it gets bigger instead of getting smaller,
• 26:40
  Speaker 1: and so the opposite effect is cool. When you apply
• 26:42
  Speaker 1: pressure to ice, it tends to melt because you're squeezing
• 26:45
  Speaker 1: it down to prefer to change phase down to water,
• 26:49
  Speaker 1: which takes less volume.
• 26:50
  Speaker 2: So you're saying, like, if I just put pressure on
• 26:52
  Speaker 2: my block of ice, it will melt.
• 26:54
  Speaker 1: The phase diagram of water has this weird angle on it,
• 26:57
  Speaker 1: and for some temperatures of ice, if you do increase
• 27:01
  Speaker 1: the pressure, it will turn into water.
• 27:03
  Speaker 2: So like a regular ice temperature like zero sea, that
• 27:07
  Speaker 2: would work.
• 27:08
  Speaker 1: Yeah, zero c. If you increase the pressure, it will
• 27:11
  Speaker 1: turn into water. It won't increase the temperature, right, Just
• 27:13
  Speaker 1: if you just increase the pressure and keep the temperature
• 27:16
  Speaker 1: the same, then technically it will be water. And you
• 27:19
  Speaker 1: can't really like serve that to mark because as soon
• 27:21
  Speaker 1: as you take away the pressure, it's going to turn
• 27:22
  Speaker 1: back into an ice cube. But you could deliver it
• 27:25
  Speaker 1: to hind a high pressure kilogram of water in some
• 27:28
  Speaker 1: intense container.
• 27:29
  Speaker 2: Well, what if you just kind of like squeeze it
• 27:31
  Speaker 2: between in a vice or something, you know, like a press.
• 27:34
  Speaker 2: Wouldn't that just instantly increase the pressure inside the block
• 27:37
  Speaker 2: of ice and melt it.
• 27:38
  Speaker 1: If you increase it in a press, it's gonna crush it, right,
• 27:41
  Speaker 1: You're gonna get crushed ice.
• 27:42
  Speaker 2: How much would you have to squeeze it without breaking
• 27:45
  Speaker 2: it or to increase the pressure to the melting point.
• 27:48
  Speaker 1: It depends a little bit on the temperature, But I
• 27:49
  Speaker 1: think the key thing here is you need to maintain
• 27:51
  Speaker 1: that pressure. They keep it liquid in an advice. You
• 27:54
  Speaker 1: crush it and then it like what falls it down
• 27:57
  Speaker 1: and it's no longer like contained so I'm talking about
• 28:00
  Speaker 1: like putting it in some like hyper pressure chamber.
• 28:03
  Speaker 2: Oh, I see, So you're you're saying putting it inside
• 28:05
  Speaker 2: of a tank and then rapidly pour a bunch of
• 28:08
  Speaker 2: air into the tank to increase the pressure inside the tank.
• 28:12
  Speaker 2: Would that just instantly melt the whole block or what
• 28:15
  Speaker 2: would happen?
• 28:15
  Speaker 1: I don't think it would melt the whole block instantly.
• 28:18
  Speaker 1: I think it would work from the outside in as
• 28:20
  Speaker 1: the outer layers are applying pressure to the inner layers.
• 28:22
  Speaker 1: So I don't know exactly how fast it would be,
• 28:25
  Speaker 1: but it is another way to melt ice.
• 28:27
  Speaker 2: Well, so then I guess Mark's question was which is
• 28:31
  Speaker 2: the fastest way.
• 28:31
  Speaker 1: I think the fastest way is to chop it up
• 28:33
  Speaker 1: and grind it and then pour water over it. But
• 28:36
  Speaker 1: those are just my impractical physicist ideas. I'm curious to
• 28:39
  Speaker 1: hear your thoughts as an actual problem solving engineer.
• 28:45
  Speaker 2: I think he asked the question of you, Daniel.
• 28:47
  Speaker 5: Not me.
• 28:47
  Speaker 1: Okay, well, then my answer is I'll consult with my
• 28:50
  Speaker 1: mechanical engineering friend.
• 28:52
  Speaker 2: Oh well, then my answer would be, let's try a
• 28:54
  Speaker 2: whole bunch of times. Let's see which one is faster. Okay,
• 28:58
  Speaker 2: that's that's an engineer with tech.
• 29:03
  Speaker 1: Screw first principles. Let's just try all of them.
• 29:06
  Speaker 2: Yeah, basically, well, you know, guided by first principles, you'd
• 29:09
  Speaker 2: come up with a bunch of different solutions, try them
• 29:11
  Speaker 2: out and see which one works faster. So I guess
• 29:15
  Speaker 2: the answer is for Mark is give us some money
• 29:17
  Speaker 2: and we'll we'll give you an answer. This is going
• 29:20
  Speaker 2: to take a lab and some resources here, Mark, because
• 29:23
  Speaker 2: our physicist has no clear answer here.
• 29:27
  Speaker 1: Or maybe we should crowdsource it. Maybe somebody out there
• 29:30
  Speaker 1: has a lab that can do these things and enjoys
• 29:32
  Speaker 1: melting ice cubes and has done these experiments. If so,
• 29:36
  Speaker 1: get in touch.
• 29:37
  Speaker 2: Oh there you go. It could be the latest TikTok trend.
• 29:40
  Speaker 2: What's the fastest you can melt the block of ice?
• 29:42
  Speaker 2: How big is a kilogram of water of ice?
• 29:44
  Speaker 1: A kilogram of water is not very much, right, it's
• 29:47
  Speaker 1: a thousand millimeters. It's just a leader of water.
• 29:49
  Speaker 2: Mm. Actually, I have figured out the fastest way to
• 29:52
  Speaker 2: turn this leader of ice into water.
• 29:55
  Speaker 1: For Mark, what's that?
• 29:56
  Speaker 2: I would just swap it out, take his block of ice,
• 29:59
  Speaker 2: hand him a leader of water. Are done. That's how
• 30:01
  Speaker 2: an engineer what's solved this problem.
• 30:05
  Speaker 1: We have no shortage of liquid water. Let's just serve
• 30:07
  Speaker 1: him up some of it.
• 30:08
  Speaker 2: That's right, Yeah, it's instant, an instant solution.
• 30:11
  Speaker 1: Yeah, I like it.
• 30:12
  Speaker 2: There you go. All right, well I think that answers
• 30:14
  Speaker 2: marks question. Let's get to our last question, which is
• 30:18
  Speaker 2: about the spectrum of light and heat from the human body.
• 30:22
  Speaker 2: But first let's take another quick break. All right, we're
• 30:37
  Speaker 2: getting to our last question of the day, and this
• 30:39
  Speaker 2: one is pretty interesting. It's about body heat, so things
• 30:43
  Speaker 2: might get a little hot. It comes from Elden from Australia.
• 30:47
  Speaker 1: Hello.
• 30:47
  Speaker 5: My question is about infrared light and heat and how
• 30:51
  Speaker 5: they relate to each other. I was taught that light
• 30:54
  Speaker 5: comes into the planet as visible light. It's the surface
• 30:57
  Speaker 5: of the Earth is absorbed and then reflected as a
• 31:00
  Speaker 5: lower energy infrared, which is what causes the greenhouse effect. Now,
• 31:04
  Speaker 5: what happens to the excess energy when visible light is
• 31:08
  Speaker 5: absorbed by the Earth and then re emitted as the
• 31:10
  Speaker 5: lower energy infrared. What happens to the infrared that is
• 31:14
  Speaker 5: directly radiated from the Sun. Does it hit the Earth
• 31:17
  Speaker 5: and get reflected as a lower energy microwave? Also, if
• 31:21
  Speaker 5: you stand in front of a fire, it is giving
• 31:24
  Speaker 5: off visible and infrared light, is it giving off any
• 31:26
  Speaker 5: other frequencies of light? And what is infrared's relationship with
• 31:30
  Speaker 5: the thermal heating of particles from the fire. Does the
• 31:33
  Speaker 5: fire's heat come from infrared or the oscillation of air
• 31:37
  Speaker 5: particles or maybe both? Why do we feel infrared as heat?
• 31:41
  Speaker 5: That's my main question is heat, just how the human
• 31:44
  Speaker 5: body sensors infrared. What I'm asking is essentially, how does
• 31:49
  Speaker 5: heat relate to infrared? And how does infrared relate to heat?
• 31:53
  Speaker 5: I've wondered about this phenomenon since I was a little boy.
• 31:57
  Speaker 2: Cheers, all right, awesome question or question from Eldin from Australia.
• 32:02
  Speaker 2: I feel like he's not like seven questions in there.
• 32:05
  Speaker 1: Yeah, I know Eldon is very curious about about how
• 32:08
  Speaker 1: hot he is feeling and whether it's due to infrared
• 32:11
  Speaker 1: light or what.
• 32:12
  Speaker 2: Yeah, and I've been to Australia and it is pretty
• 32:14
  Speaker 2: hot there, and also the people are pretty hot as well.
• 32:18
  Speaker 1: And the housing market I hear also.
• 32:19
  Speaker 2: Yeah, yeah, and the lizards are pretty big as well.
• 32:22
  Speaker 2: So yeah, yeah, I guess that's just maybe a kind
• 32:25
  Speaker 2: of a general question about how heat or what we
• 32:27
  Speaker 2: interpret this heat is related to infrared and the spectrum
• 32:31
  Speaker 2: of light exactly.
• 32:32
  Speaker 1: He talks about a lot of different contexts there where
• 32:35
  Speaker 1: infrared light is bouncing around and being absorbed and emitted.
• 32:38
  Speaker 1: So maybe we should start with what is infrared light anyway?
• 32:42
  Speaker 1: What are we talking about? And remember the infrared light
• 32:45
  Speaker 1: is just a kind of light. Light comes in lots
• 32:47
  Speaker 1: of different wavelengths, from very very long wavelengths to very
• 32:50
  Speaker 1: very short wavelengths, and a tiny fraction of that spectrum
• 32:55
  Speaker 1: we can see. We call it visible light. And there's
• 32:57
  Speaker 1: a lot of wavelengths of light we just can't see.
• 33:00
  Speaker 1: A red light, for example, has wavelengths that are too
• 33:02
  Speaker 1: long for us to see. Ultraviolet light has wavelengths that
• 33:05
  Speaker 1: are too short for us to see. So infrared light,
• 33:08
  Speaker 1: in the end is just light with long wavelengths too
• 33:11
  Speaker 1: long for us to see with our eyeballs.
• 33:14
  Speaker 2: Okay, that's infrared light. How would you define heat?
• 33:17
  Speaker 1: So, heat is a very tricky topic because it's used
• 33:20
  Speaker 1: in so many ways in so many different contexts. It's
• 33:23
  Speaker 1: too hot to handle, it's too hot to handle. You know.
• 33:25
  Speaker 1: There's like the colloquial sense of heat, where like you
• 33:28
  Speaker 1: are feeling warm, right, you feel like there's energy being
• 33:31
  Speaker 1: transferred to you, you're warming up. And then there's like
• 33:33
  Speaker 1: the thermodynamic definition of heat, which is maybe not so
• 33:37
  Speaker 1: useful because it's physicists using normal sounding words to define
• 33:40
  Speaker 1: something very very technical. And in thermodynamics, heat is energy transfer,
• 33:45
  Speaker 1: thermal energy transfer between systems that doesn't count as work,
• 33:49
  Speaker 1: not something that's like spinning a turbine or lifting something
• 33:53
  Speaker 1: up all that other kind of energy transfer they call heat.
• 33:57
  Speaker 2: But I think maybe you're getting a little too technical.
• 33:59
  Speaker 2: I think maybe you can just replace the word hot,
• 34:01
  Speaker 2: like what does it mean for something to be hot?
• 34:03
  Speaker 2: It is maybe kind of more of what Eldon is asking.
• 34:06
  Speaker 1: Yeah, I don't think Eldon is asking about the details
• 34:08
  Speaker 1: of thermodynamics, right, but we do.
• 34:10
  Speaker 2: Think he is, but I think he wants to translate
• 34:13
  Speaker 2: into everyday terms.
• 34:14
  Speaker 1: Yeah, and so you know what we feel as heat
• 34:17
  Speaker 1: is energy flowing from like hot objects to cold objects.
• 34:21
  Speaker 2: So something that's hot is something that has kind of
• 34:23
  Speaker 2: energy is stored in it and how the molecules are moving.
• 34:27
  Speaker 1: Heat and temperature are not exactly the same thing, right.
• 34:29
  Speaker 1: Temperature is like a measure of how much energy is
• 34:33
  Speaker 1: inside something like particles are whizzing around microscopically. If they're
• 34:36
  Speaker 1: whizzing around really really fast, the thing is hot. If
• 34:39
  Speaker 1: they're whizzing around slowly, then that thing is cold. So
• 34:42
  Speaker 1: that's temperature. It's like a property of an object. Heat
• 34:44
  Speaker 1: is the flow of energy from one thing to another.
• 34:48
  Speaker 1: So you have something that's hot and something that's cold.
• 34:49
  Speaker 1: Heat is the flow of energy from the hot thing
• 34:52
  Speaker 1: to the cold thing.
• 34:53
  Speaker 2: Okay, so you're saying something can be hot but not
• 34:57
  Speaker 2: give off a lot of heat, and something can be
• 34:59
  Speaker 2: hot and give off a lot of heat.
• 35:00
  Speaker 1: Well, it depends a little on the context. Right, you
• 35:02
  Speaker 1: have something at one hundred degrees, it's either going to
• 35:04
  Speaker 1: absorb energy or give off energy based on what it's
• 35:07
  Speaker 1: next to. It's next to something colder, it's going to
• 35:09
  Speaker 1: lose energy to If it's next to something hotter, it's
• 35:11
  Speaker 1: going to gain energy from it. But I think what
• 35:13
  Speaker 1: Eldon is talking about is like things glowing, like you're
• 35:16
  Speaker 1: standing next to a fire or you're getting energy from
• 35:19
  Speaker 1: the sun. Right, So what he's talking about is like
• 35:21
  Speaker 1: things essentially emitting light, because everything out there does emit.
• 35:25
  Speaker 1: Like you stand next to a rock, it's emitting light.
• 35:28
  Speaker 1: You can't see that light with your eye, but it
• 35:30
  Speaker 1: is emitting light. Everything emits light based on its temperature.
• 35:34
  Speaker 1: The sun emits light at certain frequencies because it's super
• 35:37
  Speaker 1: duper hot, those frequencies of light happen to be visible.
• 35:40
  Speaker 1: But everything, your body, the earth, rocks, even tiny dust
• 35:44
  Speaker 1: particles in space give off light, just usually at much
• 35:48
  Speaker 1: lower frequencies than we can see.
• 35:50
  Speaker 2: So I guess you're saying that when something is hot,
• 35:53
  Speaker 2: it naturally gives off light. But if it's sort of
• 35:56
  Speaker 2: warm and not super duper hot, then most of the
• 35:59
  Speaker 2: lights off is in the infrared. That's why we kind
• 36:02
  Speaker 2: of associate, at least in our human experience, hot things
• 36:06
  Speaker 2: with infrared.
• 36:07
  Speaker 1: Yeah, everything glows in infrared. But there's another aspect to this, right,
• 36:11
  Speaker 1: which is like how your body responds to these different frequencies.
• 36:14
  Speaker 1: I mean, you can see some of them with your
• 36:16
  Speaker 1: eyeballs and you can't see other ones, but also the
• 36:19
  Speaker 1: impact your body differently, Like if you have a whole
• 36:21
  Speaker 1: spectrum of light hitting you, then your body responds differently
• 36:24
  Speaker 1: to infrared light and visible light and ultraviolet light, and
• 36:28
  Speaker 1: like super duper or high energy photons and infrared light
• 36:32
  Speaker 1: actually will make you feel warmer more than those other
• 36:36
  Speaker 1: frequencies because it's very good at being absorbed by your body.
• 36:39
  Speaker 1: Like we were just talking about with microwaves, your body
• 36:42
  Speaker 1: is good at absorbing infrared radiation because it's well matched
• 36:46
  Speaker 1: to like the vibrational frequencies of your molecules.
• 36:50
  Speaker 2: And so that's I think the connection that Elvin was
• 36:52
  Speaker 2: asking about between heat and infrared, which is that what
• 36:57
  Speaker 2: we call infrared, which is really just like another frequency
• 36:59
  Speaker 2: of a light, but it just happens to be the
• 37:01
  Speaker 2: frequency of light that's just beyond our visible spectrum that
• 37:04
  Speaker 2: we can see. That range of frequencies is somehow tuned
• 37:07
  Speaker 2: to our molecules, just like the microwavease kind of exactly.
• 37:11
  Speaker 1: It can penetrate into your body and heat up stuff,
• 37:14
  Speaker 1: and you might think we'll hold on a second. And
• 37:15
  Speaker 1: the other frequencies of light actually have higher energy, like
• 37:18
  Speaker 1: ultraviolet light and blue light has a shorter wavelength and
• 37:21
  Speaker 1: a higher energy, right, And it does have more energy,
• 37:25
  Speaker 1: that's true, but you don't feel it as heat because
• 37:27
  Speaker 1: of how it penetrates your body. UV light is mostly
• 37:30
  Speaker 1: absorbed in a very thin outer layer of your skin.
• 37:33
  Speaker 1: That's why, for example, UV light will give you a sunburn,
• 37:35
  Speaker 1: and as you go even higher an energy like X rays.
• 37:38
  Speaker 1: Your body's mostly transparent to X rays. X rays will
• 37:40
  Speaker 1: pass through your body without interacting, So even though X
• 37:44
  Speaker 1: rays do have more energy, they don't deposit it in
• 37:47
  Speaker 1: your body. And even though ultraviolet light does have more
• 37:50
  Speaker 1: energy than infrared, you don't feel warm when you're bathed
• 37:53
  Speaker 1: in it because it's mostly just like toasting your skin.
• 37:55
  Speaker 2: But then if it's toasting your skin, you would feel
• 37:57
  Speaker 2: it as heat, wouldn't you.
• 37:58
  Speaker 1: Well, you do feel it as heat, sort of indirectly,
• 38:00
  Speaker 1: in the way that you're like feel a sunburn. Right.
• 38:02
  Speaker 1: You can sit out in the sun and get sunburned,
• 38:04
  Speaker 1: but you don't feel it immediately. Your skin is absorbing
• 38:06
  Speaker 1: that energy and it is getting damaged, but it's not
• 38:09
  Speaker 1: increasing in temperature the same way, right, Whereas like if
• 38:13
  Speaker 1: you are bathed in infrared light, then it's actually shaking
• 38:16
  Speaker 1: those molecules and making them wiggle. Temperature of your flesh
• 38:19
  Speaker 1: goes up, whereas if you're bathed in UV light, it's
• 38:22
  Speaker 1: mostly just like doing damage to those cells. And eventually
• 38:26
  Speaker 1: you'll feel warm because you'll feel sunburned, and that always
• 38:28
  Speaker 1: feels like uncomfortably glowy, but sort of in a different way.
• 38:31
  Speaker 2: But in either case, they're depositing energy into your body, right,
• 38:35
  Speaker 2: Like both the UV ray and the infrared are both
• 38:38
  Speaker 2: depositing energy. Is just that somehow we feel the infrared
• 38:43
  Speaker 2: energy light more or it's just your body's more efficient
• 38:46
  Speaker 2: at absorbing infrared light.
• 38:48
  Speaker 1: And your body is so efficient at absorbing ultraviolet that
• 38:50
  Speaker 1: it doesn't even penetrate very far beyond your skin. It
• 38:53
  Speaker 1: all gets deposited into your skin. You don't feel it
• 38:56
  Speaker 1: immediately as temperature because mostly it's like breaking bonds inside
• 39:00
  Speaker 1: your cells and doing all sorts of damage, whereas infrared
• 39:04
  Speaker 1: light will penetrate more deeply, but also has a different
• 39:06
  Speaker 1: effect on the particles the objects. It makes them rotate
• 39:09
  Speaker 1: and spin and vibrate. It doesn't nessally break them down,
• 39:13
  Speaker 1: but it heats it up.
• 39:14
  Speaker 2: I think you're saying, like, what kinds of light are
• 39:16
  Speaker 2: depositing energy on your body? But the UV light it's
• 39:20
  Speaker 2: being destructive when it does that, which you don't feel.
• 39:23
  Speaker 2: Like your temperature receptors in your skin are not designed
• 39:27
  Speaker 2: to feel your cells being destroyed. But the infrared light
• 39:31
  Speaker 2: sort of like the microwave, it does kind of shake
• 39:34
  Speaker 2: the molecules in your skin, which translates more directly to heat,
• 39:38
  Speaker 2: which your heat sensors are tuned to detect exactly.
• 39:42
  Speaker 1: And so if you had the option, for example, to
• 39:43
  Speaker 1: stand in front of a hundred wat uv bulb or
• 39:46
  Speaker 1: one hundred wat infrared bulb and you want it to
• 39:48
  Speaker 1: feel warm, you should stand in front of the infrared
• 39:51
  Speaker 1: bulb because it's going to more efficiently transfer that energy
• 39:53
  Speaker 1: into like the temperature of your flesh. Now, of course,
• 39:57
  Speaker 1: you do it too long, and it's going to cook you,
• 39:58
  Speaker 1: and you know that's not something we recommend here on
• 40:01
  Speaker 1: the podcast.
• 40:01
  Speaker 2: That's a little too hot.
• 40:02
  Speaker 1: He also was asking me about, like, if you stand
• 40:04
  Speaker 1: in front of a fire, what's happening there? And a
• 40:07
  Speaker 1: fire is definitely emitting in the infrared, but it's also
• 40:10
  Speaker 1: releasing a lot of chemical energy, which is just like
• 40:12
  Speaker 1: heating up the molecules of the air, and then those
• 40:15
  Speaker 1: molecules of the air are depositing energy in you. And
• 40:18
  Speaker 1: that's just like thermodynamic transfer. It's just like if you
• 40:21
  Speaker 1: stand next to something warm. In this case, the air
• 40:24
  Speaker 1: near you is warm from the fire, then that warm
• 40:27
  Speaker 1: air is depositing energy on your body, not by radiating light,
• 40:31
  Speaker 1: just by like molecules bouncing off of each other.
• 40:33
  Speaker 2: But the fire is also generating visible light, right, Like,
• 40:36
  Speaker 2: that's why you can see the fire and it's bright.
• 40:38
  Speaker 1: That's right. So the fire is heating you in lots
• 40:39
  Speaker 1: of ways. It's like directly heating the air, which is
• 40:42
  Speaker 1: heating you up, and it's also emitting light and infrared. Also,
• 40:46
  Speaker 1: everything is glowing in the infrared, and the infrared light
• 40:49
  Speaker 1: does heat you up as well.
• 40:50
  Speaker 2: All right, So then I think to answer the question
• 40:53
  Speaker 2: is like, if you have a fire gone in front
• 40:54
  Speaker 2: of you, is generating light in the almost the full
• 40:57
  Speaker 2: spectrum of light. Some of that and light being given
• 41:01
  Speaker 2: off is in the UUV, which is heating you up
• 41:04
  Speaker 2: technically destroying the cells in your body, but you're not
• 41:06
  Speaker 2: feeling as heat. Some of that light is in the infrared,
• 41:09
  Speaker 2: which you do feel as heat because your cells are
• 41:12
  Speaker 2: sort of tuned to receive that kind of energy, and
• 41:15
  Speaker 2: some of it is being transmitted to the air molecules,
• 41:17
  Speaker 2: which you then feel as hot wind.
• 41:20
  Speaker 1: And then if you have a very nice fire in
• 41:21
  Speaker 1: your backyard, increases the resale value of your house, which
• 41:24
  Speaker 1: makes the housing.
• 41:25
  Speaker 2: Market hotter, that's right, unless it gets out of control
• 41:28
  Speaker 2: and it burns your house, then you're in hot water,
• 41:33
  Speaker 2: which marked from the UK might enjoy.
• 41:35
  Speaker 1: Yeah. Or if your house is worth nothing, you might
• 41:36
  Speaker 1: actually be underwater with your mortgage, which will put out
• 41:39
  Speaker 1: the housing market.
• 41:40
  Speaker 2: And there you go, at least for your own personal finances.
• 41:43
  Speaker 1: But again, do not take real estate or financial advice
• 41:45
  Speaker 1: from this podcast.
• 41:46
  Speaker 2: Please, that's right, or engineering advice apparently from at least
• 41:50
  Speaker 2: half of the podcast. All right, well, those are three
• 41:53
  Speaker 2: really interesting questions about light, vision and heat. Thanks to
• 41:57
  Speaker 2: all of our listeners who send in their questions and
• 41:59
  Speaker 2: share their curiosity with us.
• 42:01
  Speaker 1: And thanks to everybody out there who is powering signs
• 42:04
  Speaker 1: with their curiosity and text dollars and tax dollars. The
• 42:07
  Speaker 1: combined force of everybody's curiosity is what moves everything forward.
• 42:11
  Speaker 1: So keep thinking, keep asking questions, keep wondering about the universe.
• 42:15
  Speaker 1: We'll figure it out eventually, or.
• 42:16
  Speaker 2: At least we'll try a bunch of stuff and see
• 42:18
  Speaker 2: which one works.
• 42:19
  Speaker 1: We'll sena stary requirements technically, even if not spiritually.
• 42:22
  Speaker 2: Well, we hope you enjoyed that. Thanks for joining us,
• 42:24
  Speaker 2: See you next time. Hey, it's hoar Hey from the podcast,
• 42:29
  Speaker 2: and I'm super excited to announce that my new book,
• 42:31
  Speaker 2: Oliver's Great Big Universe, is available to order now.
• 42:43
  Speaker 1: Thanks for listening and remember that Daniel and Jorge explain
• 42:46
  Speaker 1: the Universe is a production of iHeartRadio. For more podcasts
• 42:50
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• 42:54
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