Things You Thought You Knew – Where the Earth Ends

Where does the Earth end? On this episode, Neil deGrasse Tyson and comic co-host Chuck Nice explore the Karman Line, LED light bulbs, banking turns and other things you thought you knew!

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

• 0:01Neil deGrasse Tyson?

  Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. And this is gonna be a Things You Thought You Knew edition. Chuck.

• 0:24Chuck Nice?

  Hey.

• 0:25Neil deGrasse Tyson?

  Time for Things You Thought You Knew.

• 0:27Chuck Nice?

  Yes, and in my case, Things I Know I Didn't Know.

• 0:34Neil deGrasse Tyson?

  That's a very important state of mind, to know what you don't know. Because if you didn't know what you didn't know, that's just, that's just abject ignorance. I mean, there's no...

• 0:44Chuck Nice?

  That's true. That's what, that second part is sad.

• 0:47Neil deGrasse Tyson?

  Sad, exactly.

• 0:49Chuck Nice?

  That's sad.

• 0:50Neil deGrasse Tyson?

  Sad ignorance.

• 0:51Chuck Nice?

  That's terrible. That's sad ignorance, man.

• 0:54Neil deGrasse Tyson?

  Alright, so let me ask you something. How do you know how big something is?

• 0:59Chuck Nice?

  Yeah, measure it.

• 1:00Neil deGrasse Tyson?

  You measure it, right. So you pull out a ruler, let's say, let's say it's a table, and you measure it. Okay. So there are two things working against you on that. One of them is, you know, how close together are the hash lines on the ruler?

• 1:15Chuck Nice?

  Right.

• 1:16Neil deGrasse Tyson?

  Right? Because if your table ends up between two of them, then you don't know how long your table is. If you're gonna report to me, you can only say it's between here and there, and venture a guess to where it is from one marker to the next. It's kinda like half, maybe. You'll give me a guess, fine, but you won't know exactly, because you don't have the metrics to determine that. Okay?

• 1:41Chuck Nice?

  Right. It's like measuring in hands. He's seven hands tall. Really? That's all?

• 1:50Neil deGrasse Tyson?

  Well, hands is actually a specific measurement. I mean, I think a hand is four inches.

• 1:55Chuck Nice?

  Oh, really?

• 1:56Neil deGrasse Tyson?

  Width of your hand, yeah.

• 1:58Chuck Nice?

  Look at that, I see, now I just learned something there.

• 2:01Neil deGrasse Tyson?

  Horse heights are measured in hands.

• 2:02Chuck Nice?

  In hands, right. I knew that the horses were measured in hands, but I didn't know that that hand had an actual unit.

• 2:08Neil deGrasse Tyson?

  It's around four inches. Don't quote me on that, but yeah.

• 2:11Chuck Nice?

  Alright, that's cool.

• 2:12Neil deGrasse Tyson?

  Okay, okay.

• 2:13Chuck Nice?

  Good stuff.

• 2:14Neil deGrasse Tyson?

  Okay, so, so even if you had the precision to measure the length of the table, if you go down under a microscope... Like a really good microscope, like an electron microscope. That's the kind of microscopes where you see all of the hairs on the, on the, on the bugs. And you know, you see the eyeballs of the fly. Those kind of microscopes, if you do that, you'll see that the edge of the table is not smooth. It's actually got texture. So which feature of the texture are you going to measure it to and then report back to me? The width of the table.

• 2:52Neil deGrasse Tyson?

  What happens is at some point you just give up and say, Neil.

• 2:55Chuck Nice?

  I can't, I can't measure anything.

• 2:57Neil deGrasse Tyson?

  You can't, you can't measure anything unless you just agree, you just agree. How are you going to take the measurement? And then you're good with that. Well, if you have that problem with solid objects, imagine the challenge. Measuring the extent of gaseous objects. Just imagine that, okay?

• 3:18Chuck Nice?

  Yes.

• 3:18Neil deGrasse Tyson?

  So we can ask.

• 3:19Chuck Nice?

  You measure that and how bad it smells.

• 3:25Neil deGrasse Tyson?

  Not all gas came out of your rear end, okay? In this world, just saying. So, so you can ask, how high up does the atmosphere go?

• 3:36Chuck Nice?

  Okay.

• 3:37Neil deGrasse Tyson?

  Well, so you ascend and you say, is there a sign that says you are now leaving Earth's atmosphere? No, no. The atmosphere gets continually thinner. And you know this because as you ascend a mountain, the air pressure drops. It's harder for you to breathe. You can still breathe, but just every lungs worth of air has less oxygen in it. Okay, that's your evidence that the air pressure is getting lower and lower and lower. This just continues.

• 4:08Chuck Nice?

  Should have never smoked, man. God, this is killing me.

• 4:13Neil deGrasse Tyson?

  This continues. You go into an airplane, airplanes are pressurized.

• 4:17Chuck Nice?

  Right.

• 4:17Neil deGrasse Tyson?

  Which means they put air in there, otherwise you would suffocate if they opened, if you rolled down the windows. All right, so those oxygen masks, those are there in case the airplane loses pressure.

• 4:30Neil deGrasse Tyson?

  And you're breathing very low density air, has hardly any oxygen in it. So you gotta breathe through the mask, that's all, okay? By the way, you could hold your breath until you did this. I mean, this is not, you're not gonna die immediately at the fight for them. Just, it's just air, okay?

• 4:46Chuck Nice?

  Right.

• 4:46Neil deGrasse Tyson?

  You've held breath-holding contests for longer than the time it'll take you to reach for one of these yellow, yellow, um, uh, masks.

• 4:53Chuck Nice?

  Little cups, right. I remember people, always, put your own mask on first, before you try to put the mask on that of a child, so. Which, by the way, no one had to tell me, okay? Like, when I, when I heard that, I was just like, and, and what else would I have done, okay?

• 5:15Neil deGrasse Tyson?

  Chuck was first out of the box on that one.

• 5:17Chuck Nice?

  Exactly, I was like, I was like, this kid ain't bringing nothing to the table.

• 5:24Chuck Nice?

  Really?

• 5:27Neil deGrasse Tyson?

  Alright.

• 5:27Chuck Nice?

  I might, I might just let the kid pass out, just start to get some rest.

• 5:32Neil deGrasse Tyson?

  Oh, that was the noisy kid, you're not giving him the oxygen.

• 5:35Chuck Nice?

  Exactly. Wait, let's not be so quick there, ma. That kid is looking real peaceful right now.

• 5:47Neil deGrasse Tyson?

  Damn, Chuck.

• 5:48Chuck Nice?

  Alright.

• 5:49Neil deGrasse Tyson?

  That's cold, alright, so, uh, so anyhow, oh, by the way, it is also literally cold as you leave Earth's surface.

• 5:56Chuck Nice?

  Right.

• 5:57Neil deGrasse Tyson?

  So as you ascend, the air just simply gets thinner and thinner and thinner. There is no spot where you say it ends here and, and space, no, there isn't. So you just have to agree on what that altitude will be. Pick a thing, and then just, you good, you good with that, I'm good with that, fine. Put it in the books, move on to the next problem, okay?

• 6:23Chuck Nice?

  Okay.

• 6:23Neil deGrasse Tyson?

  So there's a guy in the 1960s named Carmen, okay? He was Hungarian, I think, but worked in the United States. And he said, there must be an altitude above which the atmosphere is no longer scattering sunlight above your head, so that it's no longer sky blue.

• 6:48Neil deGrasse Tyson?

  The blue goes away and then you just see stars in broad daylight.

• 6:55Chuck Nice?

  Oh, wow.

• 6:55Neil deGrasse Tyson?

  That's an interesting threshold, right?

• 6:57Chuck Nice?

  That is.

• 6:57Neil deGrasse Tyson?

  And that's fair. There'll still be air molecules there, just not enough to scatter to because that's how you get a blue sky. It scatters the blue of sunlight. And now the sky is glowing and you can't see the night sky. You can't see stars in the daytime sky. So because it's daytime. However, if you ascend high enough in the atmosphere, there's a point where there aren't many molecules above you. Bada bing, the sun is still there, but you can see stars. In addition to our own star in the sky. So that's called the Karman line.

• 7:30Chuck Nice?

  Okay.

• 7:30Neil deGrasse Tyson?

  Ever since the early 60s, the Karman line has been the functional definition of a transition into space, whether or not you were in Earth orbit.

• 7:40Chuck Nice?

  Interesting.

• 7:41Neil deGrasse Tyson?

  Our first astronaut, Alan Shepard, went up in 1961. He went into low, he went to suborbital, was fished out of the Atlantic. Okay, and he went high enough to go above the Karman line. So that counted. And so that's sort of our astronaut threshold. Karman himself, however, knew that the atmosphere is not some rigid thing. It's gas. And sometimes it heats up, sometimes it cools down, so it will expand, it will shrink. And so, so those, the Karman line is not itself a definite thing. But if you're gonna look for it, it would, you'd find it between anywhere between 80, 85 and 100 kilometers.

• 8:26Neil deGrasse Tyson?

  Okay, that would convert to 53 to 62 miles up.

• 8:31Chuck Nice?

  Okay.

• 8:31Neil deGrasse Tyson?

  Somewhere in there, okay? And so, so to say, did you hit this exact point or not? That's like arguing, you know, which, which edge of the table are you using to give me the length of the table? Except worse because it's gas.

• 8:48Chuck Nice?

  Right.

• 8:49Neil deGrasse Tyson?

  So, uh, point is, the atmosphere continues out for thousands of miles.

• 8:54Chuck Nice?

  Oh no.

• 8:55Neil deGrasse Tyson?

  Yeah, in fact.

• 8:57Chuck Nice?

  Wow.

• 8:57Neil deGrasse Tyson?

  The International Space Station, which is 250 miles up.

• 9:03Chuck Nice?

  Right.

• 9:04Neil deGrasse Tyson?

  Two hu- how much higher than the 62 mile Karman line is? It's four times higher than the Karman line. The International Space Station is huge. It's got the, it's like the size of a football field moving through the air. There's enough atmospheric molecules up there to hit the solar panels and the physical body to, to, to drop it to lower orbits than you, than you had originally intended. So every now and then, the space station has to boost itself up back to the, to its original target orbit because of the air molecules that hit it.

• 9:40Chuck Nice?

  That's insane.

• 9:41Neil deGrasse Tyson?

  Yes. And that's 250 miles up. So there is no edge. And if you're gonna ask me, what is the diameter of the sun? You could look this up in a book. You, you could look this up. The diameter of the sun, it'll give it to you. And you say, well, wait a minute. The sun is made of gas.

• 9:57Chuck Nice?

  Right.

• 9:57Neil deGrasse Tyson?

  So how precisely are you measuring that? Did you take a ruler and do that? Not only that, you can say, in what wavelength of light did you measure the diameter of the sun? Do you know different wavelengths of light emanate from different locations within the depth of the sun?

• 10:19Neil deGrasse Tyson?

  If you, if you're like Geordi on, on Star Trek: Next Generation, and you look at the sun in ultraviolet light.

• 10:26Chuck Nice?

  Right.

• 10:27Neil deGrasse Tyson?

  It has a different dimension from what it has if you look at it in visible light, and if you look at it in infrared light. Then if you look at it in X-rays, all different dimensions. In fact, the solar corona, the thing that's glowing outside of the, the moon when you see the total solar eclipse, that's called the corona, which is Latin for crown, so sensibly, right? So, so if you looked at that with X-rays, that's the size of the sun. Forget the down on the sun's surface, gaseous surface, X-rays, the corona is ablaze with light. And you're gonna say, the sun is huge. So I just wanna say, just wanna put it out there, that...

• 11:12Neil deGrasse Tyson?

  The dimensions of things is really just something you just have to agree to in advance. And then you all agree, you put it in the book, and then you move on. So the diameter of the sun is the diameter it shows to us using yellow light, which is right in the middle of the visible spectrum. That's the number you're gonna read in the book. But they don't tell you that, but I'm telling you that.

• 11:34Chuck Nice?

  I'm glad you did, cuz it's good to know they've been lying to me all this time.

• 11:43Neil deGrasse Tyson?

  Oh, by the way, and you can think of other definitions of space. I got one for you. You ready? So airplanes use fuel. Our common understanding of fuel is you burn it and then you get energy. But what does it mean to burn it? It means it gets attached to the oxygen molecule, creates a third other product, right? There's that molecule, the oxygen molecule. They merge and make this other molecule, and it's exothermic. Energy gets generated. Okay. That's how cars work. That's how airplanes work. Well, where's it getting its oxygen from? The atmosphere, okay? Wait a minute, but if you're a rocket,

• 12:25Neil deGrasse Tyson?

  and you're going to where there is no oxygen, where there's not much oxygen, you gotta bring your own oxidizer. You can't depend on the atmosphere. So you could say you enter space at an altitude where an airplane can't get enough oxygen to fly anymore. And it just drops out of the sky. That's an interesting threshold. You could have done it that way. Because above that, you need a rocket. And we all know rockets equal space. Okay? I can think of 10 other ways you might define it. But I'm just saying that just numbers and measurements of things are not they're not written in tablets.

• 13:08Neil deGrasse Tyson?

  You have to agree on what it is you're trying to measure, write down that number, and then move on.

• 13:15Chuck Nice?

  There you go. Measurements, not written in tablets, only commandments.

• 13:22Chuck Nice?

  All right.

• 13:23Neil deGrasse Tyson?

  Yeah, that's a crazy subject, but I had to put it out there.

• 13:26Chuck Nice?

  Oh, that's very cool.

• 13:27Neil deGrasse Tyson?

  And when you hear people arguing over the Karman line, just sit back and chuckle and say, the Karman line is an idea more than is an actual place within Earth's atmosphere.

• 13:37Chuck Nice?

  Well, if I ever get into an argument about the Karman line, my answer will be, so how big is the sun?

• 13:45Neil deGrasse Tyson?

  And also, the 100-kilometer Karman line? Did you really think the atmosphere is layered into even evenly divisible numbers in kilometers? Did you really think that's the case?

• 13:58Neil deGrasse Tyson?

  If you look up Karman line, it's 100 kilometers. Yeah, the Earth is like tight with the with the with the metric people, right? It's like, no, 100 is well above whatever Karman was talking about. But if you want to round it up, you round it up to 100 kilometers, and that's the definition. Fine. Okay?

• 14:15Chuck Nice?

  That's actually kind of cool, man, when you think about it. It's, I mean...

• 14:18Neil deGrasse Tyson?

  And by the way, the American definition is is lower than that. We're like 85 kilometers up. We have a lower definition than Europe and the rest of the world do.

• 14:26Chuck Nice?

  Oh, well, yeah, that's that's because, you know, we want to be able to say we went to space.

• 14:31Neil deGrasse Tyson?

  We want to be able to say that Alan Shepard went to space.

• 14:33Chuck Nice?

  With the space.

• 14:34Neil deGrasse Tyson?

  Correct.

• 14:34Chuck Nice?

  Exactly. We're the first people to do it, you know?

• 14:37Neil deGrasse Tyson?

  Right, right.

• 14:37Chuck Nice?

  Right. It's just like, we we put a spire on top of the Freedom Tower, and it's like now the tallest building in the country.

• 14:46Neil deGrasse Tyson?

  Exactly. All right, dude.

• 14:50Chuck Nice?

  All right, man. Good stuff.

• 14:51Neil deGrasse Tyson?

  All right, Chuck, we got to end it there. But if you hang on, when we return, we'll go into another segment of doing some explaining.

• 15:02Neil deGrasse Tyson?

  You know, stuff you thought you knew. That's what this is all about when we return.

• 15:14Speaker 02

  Hi, I'm Chris Cohen from Hallworth, New Jersey, and I support StarTalk on Patreon. Please enjoy this episode of StarTalk Radio with your and my favorite personal astrophysicist, Neil deGrasse Tyson.

• 15:34Neil deGrasse Tyson?

  So Chuck, we're back. Okay. For another explainer. This one, did we talk about this before? I have a bad memory for what I've been talking about. But I'm gonna do it anyway, and if not, we'll just do it again. Here it is. You ready? Okay. Okay. So there's an interesting difference between being an astrophysicist and being a photographer. Okay? Okay. Here's the difference. A college education?

• 16:01Neil deGrasse Tyson?

  I mean...

• 16:03Neil deGrasse Tyson?

  I'm sorry.

• 16:06Neil deGrasse Tyson?

  Okay, here's the difference. We know that when you have an object and you heat it, and its temperature rises, it actually radiates energy. Okay? Mm-hmm. If it's very cold, it'll radiate radio waves and microwaves. In fact, the whole universe is three degrees absolute zero... Three degrees above absolute zero. Very cold. At that temperature, microwaves get emitted. So the universe is a source of microwaves upon us because of that leftover temperature from the Big Bang. Heat... Anything more, I don't care what it is.

• 16:47Neil deGrasse Tyson?

  Heat it some more, and then the energy it'll start giving us will start shifting in the spectrum, and then it'll start giving us infrared energy. Okay. You can't see it. It's not glowing visibly yet. But if we have sensors that are not our eyes to detect infrared, you know what it's called?

• 17:08Neil deGrasse Tyson?

  Uh, no. Touch. Okay.

• 17:11Neil deGrasse Tyson?

  Okay? Heat, right, yeah. If it's warm, you can detect low-level infrared all the way up to high-level infrared just by getting near it and you can feel the energy. Or you can touch it and you can feel the temperature. Okay? Okay. So, so that's infrared. Raise the temperature some more... It begins to glow in the visible part of the spectrum. And it begins to glow deep red. It's still giving infrared, but now it's glowing red. So you can see it. So now it's like the temperature of an electric stove. Those glow red. Okay, okay. Raise the heat some more. Now you're in astrophysics zone here.

• 17:56Neil deGrasse Tyson?

  Raise the heat some more. It'll still emit the infrared. It'll still emit the red. But it will be dominated by all the colors of the spectrum. And it will look white to you.

• 18:09Chuck Nice?

  Okay.

• 18:09Neil deGrasse Tyson?

  So if something's glowing white hot, it is multiple times hotter than if it's glowing infrared hot.

• 18:17Chuck Nice?

  That's that white hot privilege.

• 18:18Neil deGrasse Tyson?

  Okay. Everything's gotta be about. Why is everything gotta? All right. Raise the heat some more. So we're about 6,000 degrees, 6,000 to 10,000 degrees absolute at this point. Okay. Raise it some more, 20, 30,000 degrees. Now it starts peaking in the blue side of the spectrum. And the object went from glowing red to glowing white to glowing blue. Raise the temperature more, some more. It still glows blue, but it's not where it peaks. It peaks beyond the blue. All right. Into the deep violet, the ultraviolet. Raise the temperature some more. It peaks in the X-rays. Okay. This is how stuff works in the universe.

• 19:03Neil deGrasse Tyson?

  Okay. So Chuck, it gets a little warmer than infrared. Now it begins to glow red. And so now it's giving you energy. It's giving you photons in the visible part of the spectrum. Say, hey, that's hot. That's glowing red hot. Okay. But I know that you can keep making the temperature higher. It'll still glow, but now it's going to glow white hot and then glow blue hot. And the blue hot is the hottest of the glowing temperatures. But we don't experience that in everyday life.

• 19:39Chuck Nice?

  Nobody says blue hot anything.

• 19:41Neil deGrasse Tyson?

  Anything. They don't say that anything. Plus, ice and icebergs have this blue tone to them. So psychologically, it all feels different. But here's what's interesting. Okay.

• 19:56Neil deGrasse Tyson?

  When we transitioned from incandescent bulbs, the old fashioned Edison light bulb to LEDs.

• 20:05Chuck Nice?

  Yes.

• 20:06Neil deGrasse Tyson?

  Okay, ask yourself, why would a light bulb giving you visible light ever get hot?

• 20:16Neil deGrasse Tyson?

  Because it's glowing white hot, but it's also still giving off infrared.

• 20:24Chuck Nice?

  Mm hmm.

• 20:25Neil deGrasse Tyson?

  Okay, so, but wait a minute, I have a light bulb so that I can see. So the 100 watt light bulb, or whatever the wattage you bought, it turns out most of that energy is coming out in the infrared.

• 20:40Chuck Nice?

  Yes.

• 20:41Neil deGrasse Tyson?

  It's a waste.

• 20:44Chuck Nice?

  Right, which is why they would always say, on the package, it would say, um, wait, wait for whatever, you know, however long, before changing the light bulb. Because so many people would be like, like, the light bulb would blow out. They would go get another light bulb, come back, well, go to change it and burn their hands.

• 21:09Neil deGrasse Tyson?

  Burn their hands.

• 21:10Chuck Nice?

  How hot the bulb was.

• 21:11Neil deGrasse Tyson?

  It's a complete waste of everybody's energy, the fact that we have light bulbs that was giving us infrared.

• 21:18Chuck Nice?

  Wow.

• 21:19Neil deGrasse Tyson?

  So, the brilliant thing about LEDs, and let me remind you, LEDs are of this next generation interior lighting. We couldn't do it until we had all three colors of LEDs. We had red LEDs.

• 21:38Chuck Nice?

  Right.

• 21:39Neil deGrasse Tyson?

  We had green LEDs.

• 21:40Chuck Nice?

  Mm hmm.

• 21:41Neil deGrasse Tyson?

  We didn't have blue.

• 21:42Chuck Nice?

  Blue.

• 21:43Neil deGrasse Tyson?

  And that would, and once we got blue, we'd have RGB. You can combine them, and RGB combined in light, don't, it's not, don't work this way in paint. Don't tell your artist friends this. You combine RGB with light and you get white light. The thing about LEDs is, they're not glowing.

• 22:02Neil deGrasse Tyson?

  They're not glowing from heat.

• 22:05Chuck Nice?

  It's actual white light.

• 22:07Neil deGrasse Tyson?

  It's actual light coming out at those frequencies, at the red frequency, at the green frequency, at the blue frequency. Your eye merges them and you see it as white light. There is no energy coming out in the infrared or anywhere else. So that's why you could have a three watt.

• 22:27Chuck Nice?

  Yes.

• 22:28Neil deGrasse Tyson?

  LED bulb that just kicks ass against a 60 watt, whatever many, five watts, whatever, against a 60 watt Edison bulb, regular old fashioned bulb, because most of that Edison energy is coming out in infrared and none of that energy is coming out infrared for the LED. It's all in the visible part of the spectrum.

• 22:48Chuck Nice?

  I don't know why we didn't do this one so much earlier because two things, and it's so exciting that you just actually did everything you just did and related it to light bulbs. One, people went crazy when we said we were going to transition to all LED light bulbs and they did it because President Blackula said that we should actually, that we should actually move to all LED light bulbs. And people were like, ah, now the government's trying to tell you what kind of light bulb you can have. No, I swear to God, it's my God getting right to have me a regular incandescent light bulb. That's America.

• 23:32Chuck Nice?

  And so people lost their minds.

• 23:34Neil deGrasse Tyson?

  This is Chuck's imitation of America.

• 23:37Chuck Nice?

  They lost their minds.

• 23:39Neil deGrasse Tyson?

  They lost their minds.

• 23:41Chuck Nice?

  And what you are saying is, one, it's more, it's more efficient because it is exactly what it is, which is.

• 23:50Neil deGrasse Tyson?

  So it's energy efficient by a factor of 10, okay?

• 23:53Chuck Nice?

  Right. And then the other thing you said was, that is why you see on the box, it's whatever many watts.

• 24:01Chuck Nice?

  Instead of like your 200 watt bulb, whatever, it's like, you know, it says, they do lumens now.

• 24:09Neil deGrasse Tyson?

  Yeah, you can't use watts, because you know what watts are? Watts is not the measure of the brightness of anything. Watts is the measure of how much energy, the rate at which it's consuming energy. And, and since we all had the same light bulbs, you could compare watts and say that one is, you know, twice, whatever, you, you had, you had some sense of that.

• 24:28Chuck Nice?

  Right.

• 24:28Neil deGrasse Tyson?

  But really with light bulbs, it should have always been measured in lumens. In fact, in Europe, I think they always measured it in lumens. So you're really, you're after lumens here, you're not after wattage, okay?

• 24:38Chuck Nice?

  And so.

• 24:39Neil deGrasse Tyson?

  So this is a maturity of the American population.

• 24:42Chuck Nice?

  Yeah, well, it's, this is, this is the best reason for you people to go out and get LED lights. I mean, for me, you know, I got into this because it's great for the environment. You know, if we all did it, we would really lessen our carbon footprint for the entire nation.

• 24:58Neil deGrasse Tyson?

  Right.

• 24:58Chuck Nice?

  But the fact is, here's why you should do it. You save money. You just, you just proved how much more efficient it is.

• 25:05Neil deGrasse Tyson?

  Save your own damn money, correct. Even if you don't care about the environment, care about your own damn wallet.

• 25:09Chuck Nice?

  There you go.

• 25:10Neil deGrasse Tyson?

  So, and that's why you can go up to any LED bulb and it's not hot. It'll never be hot. It's not about being hot.

• 25:17Chuck Nice?

  That's great.

• 25:18Neil deGrasse Tyson?

  And, and here these people, oh, Earth is flat and I don't like science and other. The person who discovered the blue LED got a Nobel Prize for that. Because the moment that got discovered, it blew open the entire lighting industry. Because now you can make white light. In fact, you can make any color light. That's why you can get LED controllers where the, the light itself has an RGB diodes in them. Um, and you can just control the ratios of those and get any color you want. And so you can, the Empire State Building is lit by these things, okay? And it's very, the intensity of the color is very real and it's very in the, in the moment.

• 26:03Neil deGrasse Tyson?

  So, so just thought I'd tell you that.

• 26:07Chuck Nice?

  That's super cool. Well, listen, white light was what we were striving for. But always remember, only black light can make your dorm room look cool.

• 26:22Neil deGrasse Tyson?

  Just to be clear, black light is an ultraviolet light. But the part of it you see is the violet. It's just kicking into the red, orange, yellow, green, blue, violet part of the spectrum. You can see that, but that's not why you have it in your dorm room. You have it because the ultraviolet light interacts with the pigment in the pictures on your wall, the posters, and it forces the pigment to glow. Okay? And it's called phosphorescence, right? And so that high-energy light that you can't see, the pigment can see, it absorbs it, and then gives it back to you in visible light, and it looks like the paintings are glowing. So in a sense, it is black light.

• 27:06Neil deGrasse Tyson?

  It is light that you can't see. Nice. Yeah. All right. Well, this was great. You got it, Chuck. So next time you walk by an LED, just pause and say, "Thank you, science." There you go. Just say that anyway. Say that anyway. Just say that anyway. Wake up in the morning, take a deep breath, "Thank you, science." Thank you, science. I should tweet that. I'm gonna do that. Let me see if I can start a movement. So Chuck, that's the end of this segment. When we come back, we're gonna do another one of these, Chuck. All right. You got it in you to listen? I got it in me. Let's do it. Okay, all right. We'll be right back.

• 27:55Neil deGrasse Tyson?

  Chuck. Hey, Neil. I'm back with another sort of stuff you thought you knew. This one might be something you didn't even know you didn't know. How about that? Some of those are out there too, right? So no one told me this. I discovered this on my own, that if, for those of you who have ridden airplanes, I know some people have never been in an airplane. I highly recommend it. It's quite a marvel of engineering and physics and aerodynamics and... Or you can watch YouTube. It's what? Or you can watch YouTube. Okay. Okay. So if you can save up, if you've never been on an airplane, find a place to fly to, and just check it out. It's quite a marvel.

• 28:36Neil deGrasse Tyson?

  And I marvel at it every day, even though we've been doing it for more than 100 years. So here's what I noticed. That my drink on my tray table.

• 28:49Chuck Nice?

  Yes.

• 28:49Neil deGrasse Tyson?

  So I notice when I pull down the shades and I can't see outside. And I I look at this drink and the water level is completely horizontal.

• 29:02Chuck Nice?

  Okay.

• 29:04Neil deGrasse Tyson?

  But that means we're just there. We're not, you know, accelerating or banking or turning. Okay, it's just there. And it stays that way the entire trip.

• 29:14Chuck Nice?

  Right.

• 29:16Neil deGrasse Tyson?

  Now, I know the plane has got to make some turns when it comes near. I know it's got to do this at some point.

• 29:23Chuck Nice?

  Right, yes.

• 29:25Neil deGrasse Tyson?

  If it does that, I would expect the water level to tilt within the glass. I'd expect me to lean in one way or another at the way that would happen in a car. If you make a a left turn in a car, your body leans to the right.

• 29:45Chuck Nice?

  Yes.

• 29:45Neil deGrasse Tyson?

  Okay, because you actually want to keep going in a straight line, but the car is curvy in front of you. So it feels like you're getting pushed to the right, but really you're just going in a you you want to go in a straight line. The car won't let you. You're getting pushed against the door. Okay. Or you turn left or right, whichever. Or someone's sitting next to you, your shoulders will touch. All right. No longer does that happen on an airplane. So what I did was let me try this with the shade up. I do it with the shade up. I look out this window, I see sky. I look out across the plane, I see the ground. This sucker is banking and yet the water on my table is completely flat.

• 30:24Chuck Nice?

  Okay.

• 30:26Neil deGrasse Tyson?

  So there's only one thing that can be happening here, because I don't think humans have this ability. The computer is flying the airplane. And you program into the computer such that the radius of the turn and the speed at which you're going requires that the plane be at a certain banking angle.

• 30:51Neil deGrasse Tyson?

  So that all the centrifugal forces combine with gravity, so that you don't even know you're banking this turn. In other words, in other words, the urge to fall into the middle of the circle gets completely balanced with the centrifugal force to send you out of the circle, so that the gravity vector still goes directly to the bottom of the glass and to your rump into the chair. And you don't even know the plane is turning.

• 31:25Neil deGrasse Tyson?

  This, those three numbers, if you, if you choose them correctly, you can have them conspire so that you would never know the plane was ever turning at any time.

• 31:36Chuck Nice?

  Well, clearly you have never been on Spirit Airlines.

• 31:43Neil deGrasse Tyson?

  The pilots in there.

• 31:46Chuck Nice?

  They don't even, they don't even use the joystick, they use a actual steering wheel.

• 31:55Neil deGrasse Tyson?

  I'm sure it's a fine airline where they have fully trained pilots. But the precision necessary to do that, to do that reliably, to do that without the judgment of the pilot, is, um, that, that takes a computer. And if you look at old movies, where they show people on airplanes and the airplane is turning, you'll see people sort of leaning to the one side or the other. That is no longer a thing in airplanes.

• 32:21Chuck Nice?

  So, and, and, and you know what you just reminded me of? When you're talking about going back, is old episodes of Star Trek, the first Star Trek, where the entire crew would go to the left, and then they go to the right.

• 32:38Neil deGrasse Tyson?

  Hold on.

• 32:41Neil deGrasse Tyson?

  And they'd all be instructed to do this, right?

• 32:43Chuck Nice?

  Right.

• 32:44Neil deGrasse Tyson?

  So they take the camera and tip the camera, right?

• 32:46Chuck Nice?

  And they tipped the camera and they would all do that to make it look like they were banking, and they were in space, so.

• 32:53Neil deGrasse Tyson?

  So, if you, if you bank a turn properly, you never feel that, that effect. And by the way, we've talked about this with NASCAR, alright? What the banked turn in a racetrack, there is a speed with which you can drive your car so that you never have to touch the steering wheel. And the car will make a complete turn on that bank and end up going back the other way.

• 33:18Chuck Nice?

  Right.

• 33:19Neil deGrasse Tyson?

  And that speed is one where you will not feel like you're leaning to the left or the right. Because the steering wheel will always-

• 33:26Chuck Nice?

  The road is turning for you.

• 33:27Neil deGrasse Tyson?

  The road is turning the car for you. Correct. And at the right speed, you'll feel the gravity vector doing whatever was doing before you entered that turn. It's the same physics principle. At work there. So, I just thought I'd put that out there, just a little discovery I made. I haven't checked with anybody who did it and when it started, but I began noticing it. And you should notice it too. Check it out. There could be sky here and brown down there. And you don't even notice it, unless you look out the damn window.

• 33:59Chuck Nice?

  Yeah.

• 34:00Neil deGrasse Tyson?

  You're saying.

• 34:01Chuck Nice?

  Well, I fly Spirit, so I'd notice it.

• 34:05Neil deGrasse Tyson?

  It's tough. Wait, one last thing. If you are in space.

• 34:12Chuck Nice?

  Uh huh.

• 34:14Neil deGrasse Tyson?

  There is no banking of turns.

• 34:19Chuck Nice?

  Yes, right.

• 34:20Neil deGrasse Tyson?

  Well, I'll tell you why. Because, so, on a track, the thing that's turning the car for you is the road itself. Okay, that's a force there that's turning the car. If you are in an airplane, you are banking on a cushion of air as you complete your turn.

• 34:39Neil deGrasse Tyson?

  If you're in space, there is no force doing that. So, if you're in space, you just have to fire rockets.

• 34:45Chuck Nice?

  Right.

• 34:46Neil deGrasse Tyson?

  And, and so, so, they don't tip and turn. It looks cool when the TIE fighters did that in Star Wars and, and the Millennium Falcon. You know, it looks cool, but that's not how it would happen. You just have the rockets change the direction that it turns in.

• 35:04Chuck Nice?

  So, all of those maneuvers that you see the Millennium Falcon make when it's-

• 35:09Neil deGrasse Tyson?

  Yeah, they're maneuvers for, they're atmospheric maneuvers, they're not vacuum-

• 35:13Chuck Nice?

  None of that means anything.

• 35:15Neil deGrasse Tyson?

  Right, right, right.

• 35:16Chuck Nice?

  Yeah, wow.

• 35:17Neil deGrasse Tyson?

  Plus, didn't they, at the end of the Star Wars, Episode 4, when they had the, you know, they were celebrated for destroying the, you know-

• 35:28Chuck Nice?

  The Death Star?

• 35:28Neil deGrasse Tyson?

  The Death Star, they, didn't they just fly in from an open bay? Exposed to the vacuum of space? And then they just get out and walk around?

• 35:42Chuck Nice?

  Yes. Uh, but I think there's a force shield that holds the atmosphere inside the ship, though.

• 35:49Neil deGrasse Tyson?

  You just made that up right now.

• 35:51Chuck Nice?

  No, no, I'm serious.

• 35:53Neil deGrasse Tyson?

  Okay, okay.

• 35:54Chuck Nice?

  Yeah, no, I'm serious. That's, I think that's how it works.

• 35:56Neil deGrasse Tyson?

  Okay, magic force fields. Okay.

• 35:58Chuck Nice?

  Yes, they're like, yeah. I mean, but seriously, there is nothing in Star Wars that, that's scientific. Let's be honest. I mean, seriously.

• 36:05Neil deGrasse Tyson?

  You know, the least believable thing to me was here's the, here are the fighters coming in and there's the guy with, with, with the traffic cones directing. It's like.

• 36:15Chuck Nice?

  They still, right.

• 36:17Neil deGrasse Tyson?

  You don't have a better way to do this in the 25th century or whenever the hell this thing takes place?

• 36:22Chuck Nice?

  And the other thing is too, they all fly in and, um, nobody fires retro rockets.

• 36:28Neil deGrasse Tyson?

  Oh, they just slow down.

• 36:29Chuck Nice?

  They just slow down. Like in Star Trek, though, when you fly into a shuttle bay, uh, there is a kind of like a tractor beam that grabs you and then you come in and that's how you stop.

• 36:40Neil deGrasse Tyson?

  Correct, correct. Because Star Trek thinks about science.

• 36:42Chuck Nice?

  Yeah, but Star Wars, they're just like, you know, coming in. I'm coming in hot.

• 36:52Neil deGrasse Tyson?

  All right. So this is, this is airplane banking 101.

• 36:55Chuck Nice?

  Yes. Well, that's cool, actually.

• 36:58Neil deGrasse Tyson?

  On Star Trek, this is a quickie. That's all I gotta tell you about it. So, uh, next time around a plane, watch for it. All right. That's all we've got time for, Chuck.

• 37:06Chuck Nice?

  All right.

• 37:07Neil deGrasse Tyson?

  All right. This has been, uh, an explainer jamboree. Stuff you thought you knew in three segments. And so I hope you like these, Chuck, because I, you know, I bend your ear on them.

• 37:16Chuck Nice?

  I love them. Uh, they're great. I mean, and I actually do learn stuff. And I gotta tell you, man, that, I mean, they're, they're, it's really, it's great information to have at a cocktail party.

• 37:28Neil deGrasse Tyson?

  Okay. Cause you'd otherwise just be completely boring and come up, I gotta pull out a nihilism here, just.

• 37:35Chuck Nice?

  Exactly. It's like, you should go talk to that guy. I thought he was a stupid comedian, but God, he's brilliant. God, he's brilliant.

• 37:44Neil deGrasse Tyson?

  I thought he was a stupid comedian. What kind of stuff?

• 37:49Neil deGrasse Tyson?

  All right. Uh, we'll call it quits there. This has been StarTalk. Stuff you thought you knew. Neil deGrasse Tyson here, as always. Keep looking up.