Neil’s Guide to Heat Transfer Physics

How do you make some things stay hot and others stay cool? Neil deGrasse Tyson, with the help of comedian Chuck Nice, explains the physics of heat transfer, insulation, and why your Stanley cup can keep your drink cold during a fire.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Neil deGrasse Tyson?

  I'm gonna make the walls of a material that is bad at conduction.

• 0:05Speaker 01

  Right.

• 0:06Neil deGrasse Tyson?

  Bad at convection and bad at radiation.

• 0:10Speaker 01

  I got a heat prison. That's what I got. I believe we have, what we have here is a failure to radiate.

• 0:28Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide.

• 0:37Neil deGrasse Tyson?

  StarTalk begins right now. Chuck.

• 0:41Speaker 01

  Yeah.

• 0:42Neil deGrasse Tyson?

  I'm gonna talk to you about heat transfer.

• 0:44Speaker 01

  Oh, right. Did, did heat put in for a transfer?

• 0:49Speaker 01

  I cannot take these conditions any longer.

• 0:54Speaker 01

  I have put it in for a transfer right now. This is a hostile work environment.

• 1:00Neil deGrasse Tyson?

  All right. So, basically.

• 1:03Speaker 01

  Uh huh.

• 1:03Neil deGrasse Tyson?

  Unless you pump energy into a system, a system left all by itself.

• 1:09Speaker 01

  Okay.

• 1:09Neil deGrasse Tyson?

  Okay. Energy will go from the thing that's hotter to the thing that's colder.

• 1:15Speaker 01

  Right.

• 1:16Neil deGrasse Tyson?

  That is not some great revelation.

• 1:18Speaker 01

  No, that is something that you learn from your mother and father.

• 1:23Neil deGrasse Tyson?

  Exactly. Okay, okay.

• 1:24Speaker 01

  Shut the damn door.

• 1:27Speaker 01

  The hell, you trying to heat the whole neighborhood?

• 1:33Neil deGrasse Tyson?

  Okay. So someone serves you a hot bowl of soup.

• 1:36Speaker 01

  Right.

• 1:37Neil deGrasse Tyson?

  Say you're eating in room temperature. So it's, you know, 72 degrees.

• 1:41Speaker 01

  Right.

• 1:41Neil deGrasse Tyson?

  Uh, what would that be Celsius? 22 degrees Celsius, something like that. Okay. 72 degrees. They serve you a cup of soup. All right. The soup is hotter than the air temperature.

• 1:52Speaker 01

  Absolutely.

• 1:54Neil deGrasse Tyson?

  What happens if you wait long enough?

• 1:56Speaker 01

  My brother will eat the soup.

• 2:00Neil deGrasse Tyson?

  That's That's how that goes. That's how that goes. Okay, not in your household. Oh, okay. In a laboratory. Just generally. Oh, yeah, of course, the soup cools to room temperature. The soup goes down to room temperature. There you go. Right. There was a heat transfer between the soup and the air. Right. Okay, now, the air, it takes a lot of heat to heat all the air in your room. Right. So it's not like the soup turned the seventy-two degrees into a ninety-degree room. Right. All right, but that energy is in the room, and it did make some tiny difference in the overall temperature of the room. Right. So now, we bring out some ice cream.

• 2:39Neil deGrasse Tyson?

  Most freezers go to zero degrees Fahrenheit. Right. You bring out the ice, it's hard to scoop at that temperature, but fine. Here's a bowl of ice cream at zero degrees. Okay. If you go away and come back and we're not at your house. I was gonna say, that's not a smart move. Leaving ice cream out. Eventually, what happens? Um, if you have a bowl of ice cream at zero degrees and you sit on the counter, it's going to go to room temperature. It's gonna go to room temperature. So, it's gonna melt first and then go to room temperature, and so, in the first case with the soup, heat went, heat energy went from the soup to the air. Right. In the case of the ice cream, it went from The air to the ice cream.

• 3:21Neil deGrasse Tyson?

  To the ice cream, okay? So the heat's gonna go wherever it's needed. Right. All right, now, how do you prevent that from happening? Okay? Um, you eat the ice cream very quickly. Okay.

• 3:38Neil deGrasse Tyson?

  Can we leave your household for a minute here, please?

• 3:42Neil deGrasse Tyson?

  So, one way to prevent that is, let's put a cover over your soup. Right. Because you just went to the bathroom. Right. And I don't know how long it takes you to poop, but you want hot soup when you come back, I will cover it. Yes. Okay? Gotta go clear some self-space back to this soup. So if you cover it, the hot air immediately above the soup Right. does not rise up. Right. Pulling heat out of the soup. It stays there, okay? Now, what happens? That hot air gets the lid hot. Right. Okay, but there's a time delay there. Right. And, by the way, if it gets the lid hot, then the lid will make the air hot. Yes. But it'll do that

• 4:28Neil deGrasse Tyson?

  Via conduction.

• 4:30Chuck Nice?

  Okay.

• 4:31Neil deGrasse Tyson?

  Conduction is one way that heat transfers. A molecule touches another molecule.

• 4:36Chuck Nice?

  Mm hmm.

• 4:37Neil deGrasse Tyson?

  And it says, there you go. There's some energy. There you go. Okay. You got it?

• 4:42Chuck Nice?

  Got it.

• 4:42Neil deGrasse Tyson?

  Okay. Conduction is the least efficient means of energy transfer.

• 4:49Chuck Nice?

  Right.

• 4:50Neil deGrasse Tyson?

  Okay. Least efficient. So, a- an example of this is you have a fireplace poker. You put one end in the fireplace. Let's say it's a yard long or something, a meter long. And you just sit there. Eventually, your handle will get hot.

• 5:05Chuck Nice?

  At some point.

• 5:05Neil deGrasse Tyson?

  At some point.

• 5:06Chuck Nice?

  Right.

• 5:07Neil deGrasse Tyson?

  But it's got to work its way, molecule by molecule.

• 5:10Chuck Nice?

  All the way up to poker.

• 5:11Neil deGrasse Tyson?

  It's up the poker and it's gonna, the molecules vibrate, sends the vibration to the next one, to the next one, to the next one. And eventually, your handle will get warm.

• 5:20Chuck Nice?

  Right.

• 5:21Neil deGrasse Tyson?

  Eventually, okay. The rea- so, that's conduction. So, it delays it for several reasons. It traps the air. And now, the lid can only just transfer heat to the air molecules that touch it. Whereas, without the lid, the entire pocket of air sitting above your soup rises up.

• 5:43Chuck Nice?

  Right.

• 5:44Neil deGrasse Tyson?

  It says, there's heat here. Now, I have expanded and I am less dense. And if you are air that's less dense, you do what?

• 5:52Chuck Nice?

  You rise.

• 5:53Neil deGrasse Tyson?

  So, that's why heated air rises.

• 5:55Chuck Nice?

  Right.

• 5:55Neil deGrasse Tyson?

  But rises, does it leave a vacuum there? No. What happens?

• 5:59Chuck Nice?

  It pulls air behind it.

• 6:01Neil deGrasse Tyson?

  What, and this is air that's not as hot as the air that just went up?

• 6:03Chuck Nice?

  Exactly.

• 6:04Neil deGrasse Tyson?

  Okay. This is all the cooler air, the seventy-two degree air, because this air's right above the soup. Is close to the temperature of the soup. So, it rises, cold air comes in, it gets heated, and this cycles, and that's called convection.

• 6:17Chuck Nice?

  And you know, it's so funny, I used to have a home show on HGTV. And that was the first air conditioning, what you just described. They would put gas flames in a copula. And then, they would turn them on. It would heat the air at the top of the house in the copula. It would go out into the atmosphere and pull all the other air up behind it. And that was the first air conditioning.

• 6:44Neil deGrasse Tyson?

  But you couldn't just put a fan in the window?

• 6:47Neil deGrasse Tyson?

  Let's see. You gotta burn fossil fuels to get, whoop. What the hell's wrong with these people?

• 6:55Neil deGrasse Tyson?

  All right, so conduction is slow. Convection is fast. Right. Okay. You know what's even faster? Than convection? Yes. Radiation. Nice. Okay, I don't mean radiation, nuclear, just radiation. Not whole radiation. But just light. Just light. Okay, so. Radiation is faster, so how does that work? Um, the fact. That the bowl is hot. Right. If you pull out an infrared camera, shut out the lights, what would the bowl look like? Oh, be red and glowing. Right, why, why would you see it?

• 7:35Neil deGrasse Tyson?

  In the infrared, it is sending light energy to, it is radiating in the infrared to you. Nice. Okay. It is radiating. Now. Radiation only goes in straight lines, is an interesting fact. Okay. Okay. Did not know that. Which is why. If you, if you have a fire, a fireplace, or I remember in camp, would be a little cold at night, they'd have a fire, a fire. If somebody walks in front of you. Right. You're in their heat chat. Yeah, exactly, you're like, can you please move, I'm trying to get some fire. That's right. You take it by my fire, bro. Exactly. Yes.

• 8:15Neil deGrasse Tyson?

  So, most of the time when people huddle near a flame, it's not because the fire made the air hot. Because any air it makes that's hot does what? It rises and. Rises up. It doesn't come out of, it doesn't come out of the fireplace to reach you. Right. It goes up. Right. Okay, so the heat you're receiving from a fireplace is radiative. Right. That is photons, in that case, infrared photons of light, coming straight to you at the speed of light. Wow. Okay. There it is, these are three ways heat moves. Okay. So, the sun.

• 8:58Neil deGrasse Tyson?

  Deep inside, stars can do any combination of convection and radiation. Okay. They don't do conduction very well. Conduction is more a solid thing. Yeah. Solid to solid. Right. That's really, so that's where you get conduction. Convection and radiation, fluids do this. Right. Okay, so when you say, oh, this thing is boiling over. Oh, no, it's, watch, watch the evolution of this. Ready? Okay, here it is.

• 9:31Neil deGrasse Tyson?

  You have a pot of water. Right. And you want to boil it. Right. Put it on the stove, turn on the flame. Yep. Okay. The water at the bottom begins to heat. Yes. Okay. Um, hot water is slightly less dense than the cooler water and it will rise. But you don't actually see this because the water, but eventually when it gets a little more vibrant, you know what you can try to do? I think I did this with raisins. You can put test particles in the water. Mm hmm. Okay, just a few. And you can watch them bob up and down. Right, right. Okay? Right. And I think I did it with raisins, but I'm trying to remember what, what, there's certain particles where you can track this. It goes to the bottom, it's hot and rises.

• 10:16Neil deGrasse Tyson?

  This is the fastest way that the water can heat itself. Because the hot pocket,

• 10:23Neil deGrasse Tyson?

  the heated pocket of water. I was gonna say, is that a pepperoni hot pocket? The heated pocket of water physically and bodily rises. And new water has to take a place, take its place. And that new water comes from a higher level that was not as hot. And that's the very fastest way you can get that to happen.

• 10:51Speaker 03

  I'm Kais from Bangladesh and I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 11:05Neil deGrasse Tyson?

  Alright, class, tell me the three ways heat can transfer. So you got, uh, convection, conduction, and radiative. Good. So now, I wanna make a vessel that heat does not either go in or come out of. Okay.

• 11:23Neil deGrasse Tyson?

  Okay, so, I'm gonna make the walls of a material that is bad at conduction. Right. Bad at convection, and bad at radiation. I got a heat prison. That's what I got. I believe we have, what we have here is a failure to radiate.

• 11:52Neil deGrasse Tyson?

  Let the record show that Chuck is repeating a line from Cool Hand Luke. Cool Hand Luke. If I remember correctly. Great movie. Paul Newman. Paul Newman, great movie. Alright, so, that's the only job of this vessel. Because if I put something hot in there, I don't want it to cool off quickly. Right. I put something cool in there, I don't want heat to get in. Right. Okay, so, one way to do that is you have two walls. Mm-hmm. Okay, let's make them glass for a moment, because glass is, is moldable. That's how, why we have bottles and things. Of course.

• 12:33Neil deGrasse Tyson?

  So, let's make two layers of glass, and have air in between the glass. I mean, a lot of windows are, are constructed that way. Yes, yes, yes. A lot of windows are constructed that way. When you have double pane. Double pane windows. Double pane windows, have, and that's an insulating feature of the window. Right. Insulates, okay. Because insulation is the other word for what I'm trying, uh, you have a better term, heat prison, okay?

• 13:00Neil deGrasse Tyson?

  What heat prison material you got for me? So, so you have air there, so now, if I put something hot inside. It'll make the glass hot. Right. Just by conduction, okay, it's touching the glass. Right. Now the glass is hot.

• 13:17Neil deGrasse Tyson?

  Alright, so now the glass is gonna heat the air.

• 13:21Chuck Nice?

  Right.

• 13:22Neil deGrasse Tyson?

  But now the air is just gonna go up.

• 13:24Chuck Nice?

  Right.

• 13:24Neil deGrasse Tyson?

  The air is trapped inside the thing.

• 13:27Chuck Nice?

  Hmm.

• 13:27Neil deGrasse Tyson?

  Where is it taking the heat?

• 13:28Chuck Nice?

  I'll tell you where.

• 13:29Neil deGrasse Tyson?

  Physically take the heat anywhere.

• 13:31Chuck Nice?

  It's stuck in there, just like Andy Dufresne.

• 13:36Neil deGrasse Tyson?

  How many movies?

• 13:39Neil deGrasse Tyson?

  And?

• 13:40Chuck Nice?

  Andy Dufresne. I believe I was gonna meet him at Montau- Montaukano Negro.

• 13:48Neil deGrasse Tyson?

  Is that where that was?

• 13:49Chuck Nice?

  I don't know where it was. It was, it was someplace down in Mexico or whatever.

• 13:53Neil deGrasse Tyson?

  Yeah, yeah, some coast of Mexico.

• 13:55Chuck Nice?

  Yeah, meet, meet me there, Andy.

• 13:57Neil deGrasse Tyson?

  And? So Chuck, so the original title of that was Rita Hayworth and the Shawshank Redemption.

• 14:04Chuck Nice?

  Okay.

• 14:05Neil deGrasse Tyson?

  Uh, cuz she was the first pinup girl that they put on the wall.

• 14:08Chuck Nice?

  Yeah, I mean, very small role in the film for her to get billing. Can't believe Stephen King gave her top billing.

• 14:17Chuck Nice?

  You know?

• 14:17Neil deGrasse Tyson?

  Okay, back to heat prison.

• 14:20Chuck Nice?

  Prison.

• 14:21Neil deGrasse Tyson?

  Heat prison.

• 14:22Chuck Nice?

  So we got the glass, we got conduction cuz it's touching.

• 14:25Neil deGrasse Tyson?

  Okay.

• 14:25Chuck Nice?

  We got the heat, that's convection, the air just goes up.

• 14:28Neil deGrasse Tyson?

  But it just goes and it stays inside the bottle.

• 14:30Chuck Nice?

  Right.

• 14:30Neil deGrasse Tyson?

  Okay, any convection stays there, but it's still touching the other side of the glass.

• 14:35Chuck Nice?

  Right.

• 14:35Neil deGrasse Tyson?

  But this is, well, this is delay. These are delaying tactics, okay? So now, uh, we, we need conduction to heat that side of the glass.

• 14:44Chuck Nice?

  Right.

• 14:45Neil deGrasse Tyson?

  And then it has to get through the glass, and typically that's in another canister that's surrounded. You're not holding on to glass.

• 14:50Chuck Nice?

  No.

• 14:50Neil deGrasse Tyson?

  There's something else, so it's gotta get through that, okay?

• 14:54Chuck Nice?

  Right.

• 14:54Neil deGrasse Tyson?

  So that is a sort of early version of a heat prison. The early thermoses.

• 14:59Chuck Nice?

  Right.

• 14:59Neil deGrasse Tyson?

  Were, uh, I remember if you dropped them, you could break the glass.

• 15:02Chuck Nice?

  Say goodbye to your thermos.

• 15:03Neil deGrasse Tyson?

  Yeah, yeah, oh, by the way.

• 15:04Chuck Nice?

  It had a glass inner.

• 15:06Neil deGrasse Tyson?

  Yeah, yeah, that's right, that's right, and so then you have to throw it away. Because you broke.

• 15:10Chuck Nice?

  You broke.

• 15:10Neil deGrasse Tyson?

  You broke the, the air prison that was in there, okay?

• 15:13Chuck Nice?

  Right.

• 15:14Neil deGrasse Tyson?

  So another thing you can do, if you take out the air, then it can't even conduct to the other layer of the glass.

• 15:24Chuck Nice?

  That's right.

• 15:25Neil deGrasse Tyson?

  Okay.

• 15:26Chuck Nice?

  Yeah, cuz you can't have convection without.

• 15:29Neil deGrasse Tyson?

  Without the fluid.

• 15:30Chuck Nice?

  Without the fluid.

• 15:30Neil deGrasse Tyson?

  And there is a fluid.

• 15:31Chuck Nice?

  And the air is the medium or the fluid.

• 15:32Neil deGrasse Tyson?

  Yes.

• 15:33Chuck Nice?

  So without that, this, the heat is just like, oh, man, this is where the escape ends.

• 15:40Chuck Nice?

  This was a terrible plan, man. This was a terrible plan. I told you, we should have crawled through the poop pipe. I told you, we should have crawled through the poop pipe. You like, no, we can't crawl through a bunch of crap. Ah, that's, and now look at us, man. Here we are stuck in a vacuum. We cannot escape this heat prison.

• 16:04Neil deGrasse Tyson?

  That the beginnings of your next movie script?

• 16:06Chuck Nice?

  That's what it is. It's called Reed and Hayworth and the Broken Heat Prison.

• 16:14Neil deGrasse Tyson?

  All right. So, okay. So, um, these are all just delaying tactics. Now, watch what happens now. There is a way for the inner glass to send heat to the outer glass. And which way is it?

• 16:27Chuck Nice?

  Uh, radiative.

• 16:28Neil deGrasse Tyson?

  Which was always there, available to it.

• 16:30Chuck Nice?

  Exactly.

• 16:31Neil deGrasse Tyson?

  Okay. Because you can radiate through air as well as convect through air. So now, you can't convect. It's not conducting. So now it's radiatively sending infrared energy across the, the, the vacuum gap to the outer layer.

• 16:47Chuck Nice?

  To the outer layer.

• 16:48Neil deGrasse Tyson?

  Okay. And then that has to absorb the infrared and then get hot and then do it to the outer layers beyond there.

• 16:55Chuck Nice?

  Exactly.

• 16:56Neil deGrasse Tyson?

  Okay. So this is an improvement over air.

• 17:00Chuck Nice?

  Absolutely.

• 17:00Neil deGrasse Tyson?

  It's easier to put air inside there than to create a vacuum i- i- in a, in a, in a, in something you're giving your, your middle school children, right?

• 17:08Chuck Nice?

  That, that's really cool because you just reminded me of an article I just read yesterday about a new fiber that is being, um, constructed using aerogel. And the fiber itself is based on the fur of a polar bear because their fur.

• 17:27Neil deGrasse Tyson?

  The concept.

• 17:27Chuck Nice?

  Yeah, the concept of a, of a.

• 17:29Neil deGrasse Tyson?

  There's a lot of shaved polar bears out there.

• 17:34Neil deGrasse Tyson?

  Polar bear with a mohawk.

• 17:35Chuck Nice?

  Right. Yeah, but they're hollow. So what they do is they spin the aerogel along with another substance into these hollow fibers. And then it's like the entire garment is like a giant down jacket, but it's thin.

• 17:53Neil deGrasse Tyson?

  It's not using down.

• 17:54Chuck Nice?

  It's thin as this.

• 17:55Neil deGrasse Tyson?

  No geese were harmed.

• 17:56Chuck Nice?

  Yeah, no geese were harmed. Right, exactly.

• 17:59Neil deGrasse Tyson?

  And just to, because I work in a natural history museum, which is the only reason why I know this, but you already know it, that polar bears are just happy in and out of thirty, thirty degree waters, salty waters.

• 18:10Chuck Nice?

  Right.

• 18:10Neil deGrasse Tyson?

  Uh, because their fur is not normal fur.

• 18:12Chuck Nice?

  Right.

• 18:13Neil deGrasse Tyson?

  They're actually hollow tubes.

• 18:15Chuck Nice?

  Exactly.

• 18:15Neil deGrasse Tyson?

  So here's the thing, if in the gap, because putting a vacuum in there is very hard, it's a production issue, if you put air in there, but throw in stuff that prevents the air from convecting.

• 18:29Chuck Nice?

  Right.

• 18:31Neil deGrasse Tyson?

  Right?

• 18:31Chuck Nice?

  Yeah.

• 18:32Neil deGrasse Tyson?

  But put in anything, put, put, put, pudding.

• 18:37Neil deGrasse Tyson?

  No, no, no.

• 18:37Chuck Nice?

  That's right, because it's gotta be, it can't be pudding, because that.

• 18:40Neil deGrasse Tyson?

  That itself.

• 18:41Chuck Nice?

  It's itself, it's like, like water or something.

• 18:43Neil deGrasse Tyson?

  Right, right. So you put something in there that's sort of light and fluffy that prevents the convection.

• 18:47Chuck Nice?

  Like 3M.

• 18:48Neil deGrasse Tyson?

  Okay, and that, if something's there, that would also prevent the radiation.

• 18:53Chuck Nice?

  Right.

• 18:53Neil deGrasse Tyson?

  From going through it. Well, it'll get absorbed by the thing and then have to, it just delays it even further. That's the whole point of these, of these vessels that we're trying to invent. Okay, so, so the first plan is you put in air.

• 19:06Chuck Nice?

  Right.

• 19:07Neil deGrasse Tyson?

  Second point, you put in, put in something to prevent the air from convecting.

• 19:11Chuck Nice?

  Right.

• 19:11Neil deGrasse Tyson?

  Third, take out the air. Fourth, you want to prevent the radiation from going, so what you put in is a radiative barrier.

• 19:20Chuck Nice?

  A barrier for radiation.

• 19:21Neil deGrasse Tyson?

  Right, nice. Ooh, so now, what you have is you put in a substance where the infrared comes out and reflects back.

• 19:31Chuck Nice?

  Wow, boom. Ow, ow.

• 19:36Chuck Nice?

  Now that's a good prison guard right there. That's what I'm talking about.

• 19:41Neil deGrasse Tyson?

  Bust you back in, right? Okay? So, so now 3M knows this, okay? If you look at, is it Tyvek, whatever it is when they're putting up homes.

• 19:52Chuck Nice?

  Yeah.

• 19:52Neil deGrasse Tyson?

  Okay, you look at the materials, very thin.

• 19:54Chuck Nice?

  Very thin.

• 19:55Neil deGrasse Tyson?

  All that matters is that he can't get through.

• 19:57Chuck Nice?

  That's it.

• 19:57Neil deGrasse Tyson?

  And they're shiny on the outside.

• 19:59Chuck Nice?

  Nice.

• 20:00Neil deGrasse Tyson?

  Okay? Shiny surfaces reflect not all light, but the light that you're gonna care about in your heating of the outside or the inside. Okay?

• 20:09Chuck Nice?

  Amazing.

• 20:10Neil deGrasse Tyson?

  So, so, we finally perfected such a vessel, and you know what we call them?

• 20:18Chuck Nice?

  What?

• 20:18Neil deGrasse Tyson?

  Thermos.

• 20:19Chuck Nice?

  Yes.

• 20:21Chuck Nice?

  Well, clearly, there's one thermos that's been perfected beyond all others, because there's a bit of craze about this thermos, or you want, they don't call it that, they call it the Stanley Cup or whatever, anyway.

• 20:32Neil deGrasse Tyson?

  With the big handle sticking out?

• 20:34Chuck Nice?

  With the big handle, it's a giant, giant cup, but this lady's-

• 20:38Neil deGrasse Tyson?

  Somebody gifted me one of those, and I said, "I have never been that thirsty."

• 20:44Neil deGrasse Tyson?

  I, you know what it is? It's a plot so that you always stop at the convenience store to pee.

• 20:49Chuck Nice?

  Right.

• 20:49Neil deGrasse Tyson?

  And you gotta buy something while you're going to the bathroom. This is a, this is a conspiracy, I'm certain of it.

• 20:55Chuck Nice?

  But this lady sees her car caught fire, and then she goes into the semi-charred remains of the car.

• 21:02Neil deGrasse Tyson?

  Wait, I think I've seen this video.

• 21:04Chuck Nice?

  Yeah.

• 21:05Neil deGrasse Tyson?

  But I haven't, I didn't pay close attention to it.

• 21:06Chuck Nice?

  Much?

• 21:07Neil deGrasse Tyson?

  Paid some attention, but what, so what's, what's the upshot?

• 21:09Chuck Nice?

  She pulls out the cup, and she shakes it, and it still has ice in it. She's like, "You see? It still has ice in it."

• 21:18Neil deGrasse Tyson?

  Well, great, all you know is that it was rattling. It could have been marbles.

• 21:21Chuck Nice?

  Could have been marbles.

• 21:24Neil deGrasse Tyson?

  Wait, as a scientist?

• 21:26Chuck Nice?

  Right.

• 21:26Neil deGrasse Tyson?

  It's probably ice, but I'm not gonna say it's ice until I've measured-

• 21:30Chuck Nice?

  Until I see that it's ice.

• 21:32Neil deGrasse Tyson?

  And measure that it's ice, okay? And it's not just marbles in there.

• 21:36Chuck Nice?

  Right.

• 21:36Neil deGrasse Tyson?

  Because as a scientist, that's how I would do that.

• 21:38Chuck Nice?

  So, anyway-

• 21:39Neil deGrasse Tyson?

  I remember now that the steering wheel's all burnt out, the dashboard was all burnt out.

• 21:45Chuck Nice?

  Yes.

• 21:45Neil deGrasse Tyson?

  But the cup holder- And every cup holder I've ever seen interact with or thought of is plastic. Always. Cup holder was unharmed by the heat. Right. So maybe the dash is on fire and the police came in to and and if I remember correctly, there was water in the bottom of one of the cup holders. Right, from where they put the fire out. Where they put the fire out. So the fire was out before it reached. Before it reached that particular part of the car. That section of the car. Right. And if it was put out and if it wasn't hot enough to melt the plastic, it's not doing a damn thing to your. To your, to your big damn cup. Your big old damn cup. Yeah. Exactly, with marbles. With marbles.

• 22:29Neil deGrasse Tyson?

  So, so I had, had the, the cup holders themselves. Been, I'm melting. Or even if the cup had been fused to the cup holder. That's what you'd think that would happen. Right. It was so hot. Cause it's so hot, right. Okay. So, so I, so that, that, all right, it's fine. Virality in social media does not have to correlate with truth. Right. Yeah, exactly. Yeah, tell me about it. Yes, thank. Yeah.

• 23:13Neil deGrasse Tyson?

  Since we were in my office, I got stuff, okay? I happen to have aerogel. Nice. Which you just described. Uh, it's inside this cube. If you look, there's like a ghost in there. Yes. It's that like. It's the ghost in the cube, not the machine. But look at that. The ghost in, let me open this up here. Now you can see in there much better. Yeah. For those who see this on video, it's a very ghost-like substance that is, has one of the highest insulating properties of any substance ever created. Aerogel are these long polymer molecules with carbon in them. And if they're long and twisted, then the air doesn't know where to go. Right. Like the ideal way to trap air. Right.

• 23:56Neil deGrasse Tyson?

  So, and especially if you have vapor barriers, the, the heat is not going anywhere. So that's why it's not a magic thing to say. That a thermos keeps hot things hot and cold things cold. Right. Because physically, what it's doing is, is preventing heat transfer. That's it. No matter which way. Which way the heat is coming, coming or going. You know what else is a good insulator is plastic. Right. Plastic. So I happen to have a lunchbox from Disney's awful movie, The Black Hole. Oh. When was this? Back in the seventies. Alright. Ten worst movies I've ever seen. Uh, I opened my lunchbox and in there is a thermos. Everything's plastic, of course, because it's a kid's thing and you don't want anything breaking.

• 24:40Neil deGrasse Tyson?

  It's got a plastic lid, so I opened that up and it's got a little sippy, um, sippy device. Fancy. Everything's pla- yeah, it's a high. It's a high end little thermos there, right? Especially from the seventies, damn. Yeah, so this is a black hole. So Chuck, you've heard of the, the, uh, black hole in the center of the Milky Way? Of course. Yeah, of course. Like six hundred million times the math of my, I think, last I checked. Well, here, uh, in my black hole lunchbox, I have, I have a Milky Way in the center. In the center of a black hole?

• 25:18Neil deGrasse Tyson?

  Now you know what? What?

• 25:21Neil deGrasse Tyson?

  Somebody, somebody need to spank you for that.

• 25:25Neil deGrasse Tyson?

  So I'm looking in here. It's plastic on the inside, plastic on the outside, but it's actually quite thick. There's a thickness to this. Right. It is. Look at that. Wow. It's very thick. That's why the inside of a thermos is always so much smaller in volume than the outside. Because relying on stuffing things in between to prevent heat transfer. That's it. So this is the, the innovation of the human brain overcoming restrictions by the laws of physics. There you go. Overcoming. Overcoming the laws of thermodynamics. Yes, exploiting them to our advantage. Screw you thermodynamics. You won't tell me how to transfer heat.

• 26:04Neil deGrasse Tyson?

  So now if I put you out in space, okay, I'll put my lunchbox back. There we go.

• 26:12Neil deGrasse Tyson?

  Say goodbye to the black hole. Goodbye, black hole. Okay, there it goes. And aerogel? Oh, I don't wanna say goodbye to aerogel. That stuff is so cool. If I put you butt naked in outer space. Right. So. Space will become exceedingly more sexy. So, um, you're not conducting, so you, heat cannot conduct from your body. Right. To space. Nope. Cause you need physical atom contact for that. Right. Okay? And. There's no convection. There's no convection. Cause there's no, it's a vacuum of fluids. This is the vacuum. So that leaves only one way for heat to transfer. Radiative. Radiative. So, if you are far away from any star, right?

• 26:55Neil deGrasse Tyson?

  Your ninety-eight point six degree body, thirty-seven degrees Celsius, will radiate what kinda light? Uh, infrared. Infrared light, cause you show up on an infrared camera in a room. Yep. It'll radiate infrared. And radiation is. Until you are dead. Until you are dead. Infrared, till you're dead, baby.

• 27:14Neil deGrasse Tyson?

  You'll just, infrared just goes, and there it goes. Right. And there's nothing to stop that. Now, when you go out in the cold, okay? Mm-hmm. In cold air. Right. You are still radiating in the way you would be radiating in space, but air is also in physical contact with your body, and the air that touches your body immediately gets heated by your skin, and that gets, uh, and it gets swept away. Right. So, um, this is why you have wind chill factors, because the air touches you, takes

• 27:58Neil deGrasse Tyson?

  your heat, and then wind blows it away. Right. And then new cold air comes in. It's almost like convection, except it's not convection, it's just wind, wind, uh, the air, um, sucks out your heat, and fresh air comes in to keep that up. So you will freeze to death much faster under windy conditions than under non-windy conditions. Wow. Now, here's an interesting fact. Mm-hmm. It was Apollo thirteen.

• 28:24Neil deGrasse Tyson?

  The ill-fated mission where the oxygen tank blew and they had to come back. I think that was it. The oxygen tank, they're on their way back and they had to conserve everything.

• 28:35Chuck Nice?

  Right.

• 28:35Neil deGrasse Tyson?

  Okay. And they couldn't heat the capsule. Otherwise, they'll run out of other resources that they needed to get back to Earth.

• 28:42Chuck Nice?

  Okay.

• 28:43Neil deGrasse Tyson?

  All right. What they figured out was when you are in zero G, which you are when you're just floating back to Earth.

• 28:52Neil deGrasse Tyson?

  If you just stay in one position and don't move, you will heat the air that's touching your skin. But the air won't know where to go after that. There's no gravity.

• 29:06Chuck Nice?

  Right.

• 29:06Neil deGrasse Tyson?

  There's no, there's no gravity vector for the hot air to rise because there is no up or down. So by just staying there, you end up creating

• 29:16Chuck Nice?

  A heat suit.

• 29:17Neil deGrasse Tyson?

  A heat, a heat blanket of just air.

• 29:21Chuck Nice?

  Air around you.

• 29:22Neil deGrasse Tyson?

  Around you. And the air itself makes a good insulator. And so that way, you, um, you, it's, it's like you're putting on a coat.

• 29:31Chuck Nice?

  Wow. Uh, Eagle, this is a control. Uh, we're not going to be able to heat you guys on the way back. Uh, but, uh, what we're, uh, what we're thinking here is that you just stay perfectly still. Uh, it's like, bro, no. Nah, bro. Uh-uh. We need a better plan.

• 29:50Neil deGrasse Tyson?

  By the way, that's why clothing works.

• 29:53Chuck Nice?

  True.

• 29:53Neil deGrasse Tyson?

  Think about it.

• 29:54Chuck Nice?

  Yeah, no, that's right.

• 29:55Neil deGrasse Tyson?

  You heat the air inside your clothes. Innocent, it's, and that's why you can go out into colder conditions and you are warmer wearing clothes than not wearing clothes.

• 30:03Chuck Nice?

  The whole, whole idea behind layering.

• 30:05Neil deGrasse Tyson?

  Yes, and it's also the idea behind a wet suit.

• 30:08Chuck Nice?

  Right, yes.

• 30:10Neil deGrasse Tyson?

  Okay. In a wet suit, remember how that works. You, it's a rubberized thing, but you get water inside.

• 30:17Chuck Nice?

  Right.

• 30:17Neil deGrasse Tyson?

  You're, it's cold at first, your body heats the water, the water stays there.

• 30:21Chuck Nice?

  Right.

• 30:22Neil deGrasse Tyson?

  Okay. And the water is protected from getting, from losing its heat to the ocean because you're surrounded by rubber. Okay.

• 30:31Chuck Nice?

  Right.

• 30:32Neil deGrasse Tyson?

  And rubber has air pockets inside of it as well. So you are nicely insulated in one, what they call a wet suit that divers know all about.

• 30:39Chuck Nice?

  Nice.

• 30:40Neil deGrasse Tyson?

  Okay, so now you're out there freezing to death.

• 30:42Chuck Nice?

  Mm-hmm.

• 30:45Neil deGrasse Tyson?

  Suppose I move you closer to a star. Let's move you closer to the sun. Oh, thank God. Okay, so now, now what's going on? Well, now I'm getting the sun's radiative heat. There you go. The sun has radiate, is radiating with energy way higher than infrared. Yes. Right? So, there's some distance, I don't know what that is, I'll have to calculate it. Uh, where, energy from the sun is just right for you. Right. Okay. Where you could be bucknaking in space. However. And comfortable? However, only the side of you facing the sun. Oh, God. The side of you where the sun ain't shine, don't shine. Right.

• 31:28Neil deGrasse Tyson?

  That's radiating out to the rest of the universe. Oh, man. One half of you is freezing, the other half, so you have to go on a rotisserie. You're on a rotisserie. And if you don't, you will literally freeze your ass off.

• 31:46Neil deGrasse Tyson?

  Freeze your ass off. Right. Off.

• 31:50Neil deGrasse Tyson?

  Clean off. That's it. Your body will split right down the middle. One part will vaporize, the other part will. So, so when they say, what is the temperature of space? That has no meaning, because you have to, as a standalone question, you have to ask, how close are you to the nearest source of energy? Right. That would be providing heat to you. There you go. Um, it's all about how heat gets around. That's it. And of course, radiation moves at the speed of light. There you go. You know? So. What that is. It is. Man, there you go, the heat transfer, baby. All right, now, uh, oh, oh, oh, one last thing. Okay. Before we land this plane. So, I, I think we did an explainer on, on boiling over. Okay.

• 32:35Neil deGrasse Tyson?

  On the stove, but everything I just described relates to that. Okay. Because if you have something where, okay, water is just slowly convecting up through, but then, when it boils violently. Yes. What's happening is, the water at the bottom.

• 32:56Neil deGrasse Tyson?

  It's not just getting hot and rising.

• 32:58Chuck Nice?

  Right.

• 32:59Neil deGrasse Tyson?

  It's turning into bubbles of steam.

• 33:02Chuck Nice?

  Right.

• 33:03Neil deGrasse Tyson?

  And, and a bubble of steam is way less dense than the water.

• 33:08Chuck Nice?

  Right.

• 33:09Neil deGrasse Tyson?

  And that steam wants to get the hell out of that pot.

• 33:12Chuck Nice?

  This is who I am now, and I got to go.

• 33:15Neil deGrasse Tyson?

  I got to go.

• 33:16Chuck Nice?

  I got to go. This is who I am. You cannot keep me here anymore, water. I am now steam.

• 33:21Neil deGrasse Tyson?

  I am now steam.

• 33:22Chuck Nice?

  I am now steam.

• 33:23Neil deGrasse Tyson?

  And the steam is trying to get out, and you've got oatmeal in the way. Well, the bubble of steam wants to get the hell out, and it's not gentle like just rising hot, heated water.

• 33:34Chuck Nice?

  Right.

• 33:35Neil deGrasse Tyson?

  And the bubble just busts up, and if it's spaghetti, if it's any food that's in the way.

• 33:42Chuck Nice?

  Right.

• 33:42Neil deGrasse Tyson?

  It's gonna take it with it, and, and there it goes. And it boils over, even if you're only half full.

• 33:48Chuck Nice?

  That's right. And while it is boiling over, as it comes out, Diana Ross is playing in the background.

• 33:57Neil deGrasse Tyson?

  Okay. I didn't know that boiling had a soundtrack.

• 34:01Chuck Nice?

  Oh, it certainly does. And it's, "I'm coming out. I want the world to know."

• 34:08Neil deGrasse Tyson?

  I forgot about that song. That's like an 80s disco song.

• 34:11Chuck Nice?

  Yeah, it is. Great song.

• 34:12Neil deGrasse Tyson?

  Okay. So, so that's the difference between convecting water.

• 34:18Chuck Nice?

  Right.

• 34:18Neil deGrasse Tyson?

  And convecting hot bubbles of, of gas.

• 34:21Chuck Nice?

  Nice.

• 34:22Neil deGrasse Tyson?

  Okay. So, so gasified water, we call steam, and that's what's going on when you boil. But we, we talked about that in another.

• 34:28Chuck Nice?

  Yeah.

• 34:29Neil deGrasse Tyson?

  On another show, but, but here is the full context connected to the transfer of heat.

• 34:34Chuck Nice?

  There you go. Plus, the last time we talked about it, we didn't have nearly this much fun.

• 34:39Neil deGrasse Tyson?

  Oh, one more, just while we're talking about boiling over.

• 34:43Chuck Nice?

  Okay.

• 34:43Neil deGrasse Tyson?

  When the sun dies, it will become a red giant star.

• 34:46Chuck Nice?

  That's right.

• 34:46Neil deGrasse Tyson?

  It will become so large, it will engulf the orbits of Mercury, Venus, and come up and just kiss the orbit of the Earth. And you might ask, how does the sun get so large?

• 34:58Chuck Nice?

  Right.

• 34:59Neil deGrasse Tyson?

  Oh, I'll tell you. Oh, well, the outer parts of the sun, okay? As, uh, as it forms larger and larger molecules, the molecules are less transparent to radiative heat.

• 35:18Chuck Nice?

  Hmm.

• 35:18Neil deGrasse Tyson?

  Transfer.

• 35:19Chuck Nice?

  So it's pushing.

• 35:20Neil deGrasse Tyson?

  So exactly, so you have what's called radiation pressure.

• 35:24Chuck Nice?

  Right.

• 35:24Neil deGrasse Tyson?

  On these larger molecules that previously it would just pass right on by.

• 35:29Chuck Nice?

  Right.

• 35:29Neil deGrasse Tyson?

  And so the more of these molecules form, the more radiative pressure exists underneath it, and the entire star balloons out rather rapidly, given the lifetime of the star. Sun will be around for a billion years, it'll blow up, it'll not blow up explosively, it'll expand just in a matter of hundreds of thousands, at most millions of years. And then life as we know it on Earth would have to have moved to another planet or would be extinct long ago for some other cause.

• 35:57Chuck Nice?

  Oh, definitely that. Please.

• 36:01Neil deGrasse Tyson?

  So let's wait, I'll give you a pop quiz. Okay, so why styrofoam make very good, um, ice coolers?

• 36:10Chuck Nice?

  Cause there's a lot of air in styrofoam.

• 36:12Neil deGrasse Tyson?

  Yeah, but air convects.

• 36:14Chuck Nice?

  Oh, that's true. Oh, I don't know that.

• 36:17Neil deGrasse Tyson?

  No, because the air is trapped.

• 36:19Chuck Nice?

  Oh, oh, it's trapped in the styrofoam.

• 36:21Neil deGrasse Tyson?

  Yeah, yeah, so you can change, you can change the temperature of the foam and the pocket of air in the foam, but the air's got nowhere to go.

• 36:27Chuck Nice?

  Right, so if there's something cold in there, then it's cold, and if there's something warm in there, then it's warm.

• 36:33Neil deGrasse Tyson?

  Right, right, and so this is why down harkas work. They trap a lot of air, they, anything that's, uh, or you, you just figure out a way to prevent, because in the old days, the, you know, you look like the Michelin Man with all your winter clothing.

• 36:48Chuck Nice?

  Yes.

• 36:48Neil deGrasse Tyson?

  If you figure out how to do that, you've gotten clever about it. With new materials that prevent all three of those heat transfer mechanisms.

• 36:55Chuck Nice?

  And then there's also the, uh, the best solution, and that is Turks and Caicos.

• 37:03Neil deGrasse Tyson?

  Okay, that's it.

• 37:05Chuck Nice?

  That's the best.

• 37:06Neil deGrasse Tyson?

  Okay. Is that in the instructions on the thermos?

• 37:10Chuck Nice?

  Yeah, that's right. It says, "Open me in Turks and Caicos."

• 37:17Chuck Nice?

  Then you gotta worry.

• 37:18Neil deGrasse Tyson?

  All right, we gotta go there. All right, Chuck, that's all I got for you.

• 37:20Chuck Nice?

  Wow, that is great. That was awesome. That was so much fun.

• 37:23Neil deGrasse Tyson?

  I didn't leave anything out.

• 37:25Chuck Nice?

  No, listen, we have, we have transferred all of the information about heat transfer to anybody who is watching.

• 37:33Neil deGrasse Tyson?

  And the better thermoses are the ones that simply take the longest for heat to either get in or heat to get out.

• 37:40Chuck Nice?

  Right.

• 37:40Neil deGrasse Tyson?

  That's all it is. It's not, it's not deeper than that. It's not magic.

• 37:44Chuck Nice?

  So stop it with your big stupid cup. Stop it, all right? Let it go.

• 37:51Neil deGrasse Tyson?

  Come back when it's fused to the plastic.

• 37:53Chuck Nice?

  Yeah, when it's fused to the plastic, then we'll, then that's a video we wanna see, all right?

• 38:00Neil deGrasse Tyson?

  All right, Chuck, always good to have you, man.

• 38:02Chuck Nice?

  Always a pleasure.

• 38:02Neil deGrasse Tyson?

  This has been StarTalk, me just blathering.

• 38:07Neil deGrasse Tyson?

  This time about heat transfer, more than you ever cared to know, but it all applies to our lives. And whether you can have a cold one waiting for you after your car burns. You're past Tyson, your personal astrophysicist. Keep looking up.