Pod Insights StarTalk Podcast Things You Thought You Knew – Up, Up, and Away! About this episode What is the rocket equation? How do airplanes fly? Neil deGrasse Tyson and comic Chuck Nice go through some things you thought you knew about how airplanes fly, x-rays, and how to fuel a rocket.
Transcript Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
0:00 Neil deGrasse Tyson? The wing is now pitched upward towards the moving air.
0:06 Chuck Nice? Right.
0:06 Neil deGrasse Tyson? It's pitched upward, so air is flying straight into the wing. That's gonna also add to the Bernoulli effect and that plane is gonna pop.
0:19 Neil deGrasse Tyson? Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. Chuck.
0:32 Chuck Nice? Yes.
0:33 Neil deGrasse Tyson? You got one of your favorite kind of episodes coming up.
0:36 Chuck Nice? All right.
0:36 Neil deGrasse Tyson? It's Things You Thought You Knew.
0:38 Chuck Nice? You are correct.
0:40 Neil deGrasse Tyson? You like those.
0:41 Chuck Nice? I do indeed.
0:42 Neil deGrasse Tyson? I'm glad you like, I like making you happy.
0:44 Chuck Nice? It's because I know that I don't know.
0:49 Chuck Nice? That is what I know.
0:54 Neil deGrasse Tyson? And so this is a way to remedy that.
0:56 Chuck Nice? That's right.
0:57 Neil deGrasse Tyson? It's a cure. All right. So Chuck.
0:59 Chuck Nice? Yeah.
1:00 Neil deGrasse Tyson? You ever wonder how airplanes fly?
1:03 Chuck Nice? You know.
1:04 Neil deGrasse Tyson? Have you ever walked up to one? And I sound like the guy in The Matrix. You ever marvel at an airplane? That 300 tons of metal.
1:15 Chuck Nice? Mr. Anderson.
1:17 Neil deGrasse Tyson? No, he was talking to, uh, Morpheus at that time.
1:19 Chuck Nice? Oh, Morpheus.
1:20 Neil deGrasse Tyson? Yeah, yeah, yeah.
1:22 Chuck Nice? That's right, cuz he was talking about, yeah.
1:23 Neil deGrasse Tyson? He was trying to get him to reveal the codes for Zion.
1:27 Chuck Nice? The codes for Zion, yes.
1:29 Neil deGrasse Tyson? Yeah, yeah, yeah. So anyhow, do you ever marvel that an airplane of all sizes, they just go fast forward and then they fly? Do you ever pause and reflect on this?
1:42 Chuck Nice? I'm not gonna say I have, to be honest.
1:47 Chuck Nice? I'd be lying.
1:48 Neil deGrasse Tyson? It's just give me the scotch before we take off and I'm good, all right.
1:53 Chuck Nice? I'll tell you what I marvel at.
1:54 Neil deGrasse Tyson? What?
1:56 Chuck Nice? How sometimes I get a really decent meal in first class. That's to me is a modern aviation marvel.
2:04 Neil deGrasse Tyson? Okay, all right, so, so here you go. So you may have noticed that all airplanes have wings.
2:11 Chuck Nice? Yes.
2:12 Neil deGrasse Tyson? Okay. So wings are a good thing. That's a good thing.
2:16 Chuck Nice? I will say.
2:17 Neil deGrasse Tyson? They also have mini wings on the tail. Okay.
2:20 Chuck Nice? Right.
2:21 Neil deGrasse Tyson? And then they have like a vertical wing, uh, which is like the stabilizer wing. And so that prevents it from sort of fishtailing. Right. Because if it's going quickly through the air and air parts on the left and right side of that tail fin, that gives the plane stability moving in one direction.
2:39 Chuck Nice? Okay.
2:40 Neil deGrasse Tyson? Now, when I was a kid, I built model airplanes that flew, uh, gliders. And I tried making gliders without a tail fin and it just fishtailed the whole time. It just didn't, it couldn't stabilize. So I, so doing piece by piece, adding and subtracting bits to my, to my models. I was able to sort of learn early on in my life what role these were playing in the stability and the lift on an airplane. Okay.
3:06 Chuck Nice? Interesting.
3:07 Neil deGrasse Tyson? Yeah, just so I go back on that way back on this. So now, um, you may have also noticed the shape of the cross section of a wing.
3:18 Chuck Nice? Yes.
3:18 Neil deGrasse Tyson? If you take a cross section of a wing, and sometimes you can see this.
3:22 Chuck Nice? Oh, yeah.
3:23 Neil deGrasse Tyson? You know.
3:24 Chuck Nice? You can see it when you're on, if you sit on the wing of a plane.
3:27 Neil deGrasse Tyson? On the wing.
3:27 Chuck Nice? When you're sitting in the wing seat.
3:29 Neil deGrasse Tyson? In the wing seat, right. So, so that's usually where the exit, there's usually an exit, uh, door above the wing so that you can step out. So, uh, so the top part is curved.
3:40 Chuck Nice? Right.
3:40 Neil deGrasse Tyson? And the bottom is, uh, it's typically flat.
3:43 Chuck Nice? Right.
3:45 Neil deGrasse Tyson? So you have a pocket of air that the moving wing is passing through. And the air wants to stay as one parcel. It wants to, okay?
3:55 Chuck Nice? Okay.
3:55 Neil deGrasse Tyson? So as you do this, the air on top to go that bigger distance has to travel faster to keep up with the air on the bottom so that when it reconnects, it's the same parcel.
4:07 Chuck Nice? Gotcha.
4:08 Neil deGrasse Tyson? All right. So you have forced the air to move faster on the top than on the bottom. And fast-moving air has lower pressure. And I've done this before. I don't know who's gonna be listening to this and who's gonna be watching it. But you can take a ribbon. So I'm gonna use my letterhead.
4:26 Chuck Nice? Okay.
4:27 Neil deGrasse Tyson? Here it is. I don't know if you can see.
4:28 Chuck Nice? From the desk of Neil deGrasse Tyson.
4:30 Neil deGrasse Tyson? That's right. It's a Hayden Planetarium, uh, at the American Museum of Natural History. So, not that it matters what paper you do use, but I'll get a nice, long, skinny strip from that. There it goes. And here it is, just limp in front of me. And now I'm gonna blow across it. Okay, here I go.
4:54 Chuck Nice? There you go.
4:56 Neil deGrasse Tyson? I'm blowing on top of it.
4:57 Chuck Nice? Top of it, but it, it, it, it straightens out, lifts up.
5:01 Neil deGrasse Tyson? Correct. So the faster air going on top has lower pressure relative to the pressure of the air on bottom. So the air on bottom presses it up.
5:10 Chuck Nice? It's pushing, right.
5:11 Neil deGrasse Tyson? It's pushing it up. You have an entire pair of wings doing this. An entire pair of wings. And the faster you move, the bigger the pressure difference is between the two of them. Period.
5:23 Chuck Nice? Huh.
5:24 Neil deGrasse Tyson? Okay. So, on the runway, where you're ready to take off.
5:30 Chuck Nice? Right.
5:31 Neil deGrasse Tyson? And the plane accelerates. The pressure difference between the top and the bottom is becoming greater and greater and greater. And the plane's saying, "I'm ready to do this," okay? But you don't wanna rely only on that. You wanna make sure this happens. So, what, by the way, it continues to accelerate through this. What the pilots do is, they, they, they up the flaps on the tailwings, okay?
6:04 Chuck Nice? Right.
6:04 Neil deGrasse Tyson? What does that do? That creates extra pressure to push the tail down, pivoting the nose upwards.
6:12 Chuck Nice? Uh huh.
6:13 Neil deGrasse Tyson? When the nose goes upwards, the upward pressure on the wings is no longer just this Bernoulli effect. Bernoulli is the guy who first uh uh decoded this phenomenon.
6:25 Chuck Nice? Uh huh.
6:25 Neil deGrasse Tyson? It's not only that, the wing is now pitched upward towards the moving air.
6:32 Chuck Nice? Right.
6:33 Neil deGrasse Tyson? It's pitched upward, so air is flying straight into the wing. That's gonna also add to the Bernoulli effect and that plane is gonna pop.
6:45 Neil deGrasse Tyson? That's why it doesn't slowly gain altitude. That plane changes its angle to the air and it flies high above the ground. And there's strong reason to do that because it also reduces the acoustic footprint of the takeoff. The higher it can get, the fastest, the the less uh influence that sound is gonna have on houses and other things that happen to be in the in the in the runway path.
7:15 Chuck Nice? Right.
7:15 Neil deGrasse Tyson? So.
7:16 Chuck Nice? Lowering your lowering property values everywhere.
7:19 Neil deGrasse Tyson? Everywhere. And so this effect of pitching the wing so that the moving air just presses it upward is so effective that you don't even need Bernoulli to fly an airplane.
7:33 Chuck Nice? Um, you know, you can have Johnson do it, or you can also, you know, Smith, Smith is cool, you know.
7:44 Neil deGrasse Tyson? You can have Ray J. Johnson do it, but you don't have to call him Ray, you can call him Ray J. Ray J. can do it.
7:49 Chuck Nice? Right.
7:50 Neil deGrasse Tyson? So that's an old timer reference there for people over seventy.
7:55 Chuck Nice? Wow.
7:55 Neil deGrasse Tyson? So so the upward pressure will do that. That's why. For example, if you've ever been to an airshow, I highly recommend it. Even if you're anti-military, the airshows like display not only military jets, but future civilian jets. But you should see what your taxpayer money is going towards, okay? If you have the occasion to visit an airshow, there there are big ones in the United States, um, in in, uh, outside of Paris, uh, and outside of London. Uh, Farnborough is one, though these are major airshows. But anyhow, the F-16, as well as other planes, the last I saw was F-16 airplane, can fly upside down and you can say-
8:35 Chuck Nice? Oh yeah, I saw Top Gun. I saw it.
8:36 Neil deGrasse Tyson? Oh.
8:38 Chuck Nice? I remember that.
8:39 Neil deGrasse Tyson? If this Bernoulli effect only pushes upwards with that orientation of the wing, how the hell do you fly upside down? You just angle the wings so that the air hitting on the front edge of it, the urge of that is to push it upwards rather than any other direction at all. And if you maintain that pitch of the wings, you can sustain a lift for the airplane. You can fly it at any angle for that. But if you're not otherwise in Top Gun or you're doing fancy things, you let Bernoulli do most of the work.
9:13 Chuck Nice? Look at that.
9:13 Neil deGrasse Tyson? And there you have it.
9:14 Chuck Nice? So you're good, yeah, just creating lift.
9:17 Neil deGrasse Tyson? Correct. Now, have you seen those little winglets at the tip lately in the last 10 years? Almost all planes have them.
9:22 Chuck Nice? Yes, all the planes have a little wing on the wing. A little wing on the wing to cute a little bit. It's like a little, it's like a little wing hand, like. Hey, hey, Slade, will the wing here?
9:32 Neil deGrasse Tyson? Alright, so they knew and learned that air moving over the wing. Oh, by the way, the wings get narrower as you get to the tip. Take a notice of that next time. They're very large as they attach to the airplane and then they get narrower. That's a very important feature for strength, by the way, okay?
9:50 Chuck Nice? Right.
9:50 Neil deGrasse Tyson? The strongest part of the wing is the nearest part to the plane, alright? That's a good fact. You don't want it breaking somewhere else, alright? Uh, so- So what you have is a, a, a, so air not only moves over the wing, but it also moves off the wing horizontally. And what they found is the air going off the tip of the wing created little turbulent eddies.
10:13 Chuck Nice? Gotcha.
10:14 Neil deGrasse Tyson? Anytime you have turbulence, you have a drag, a turbulent drag.
10:17 Chuck Nice? Right.
10:18 Neil deGrasse Tyson? And they said, is there any way to smooth over these eddies? And so they did this research under the umbrella of one of the A's of NASA. Recite for me the NASA acronym.
10:33 Chuck Nice? National Aeronautics.
10:37 Neil deGrasse Tyson? And Space Administration.
10:38 Chuck Nice? Administration.
10:39 Neil deGrasse Tyson? The first A in NASA stands for aeronautics. A big part of their budget is to study aeronautics. They discovered that if you put a little uptick, a little up, up angle in the tip of your wing, you can boost the, you can reduce the drag, thereby increasing fuel efficiency, thereby enabling cargo planes to carry that much more and that much farther.
11:05 Chuck Nice? Look at that.
11:06 Neil deGrasse Tyson? Overall, they saved between 10 and 15% of all the fuel costs the world has seen since that's been introduced.
11:13 Chuck Nice? And that is huge.
11:15 Neil deGrasse Tyson? Huge.
11:17 Chuck Nice? Yeah.
11:17 Neil deGrasse Tyson? Huge.
11:18 Chuck Nice? Yeah, I gotta tell you, that's a, first of all, I look at it like great for the ecology, you know, that's.
11:25 Neil deGrasse Tyson? Yeah, yeah.
11:25 Chuck Nice? But, but if you, if you're running an airline, you know, it's just, it's good for the bottom line.
11:30 Neil deGrasse Tyson? It's good for the bottom line. And so, and you will also notice that that little piece of the wing, if it's done in a modern design, rather than the original designs, they just slap something on there. They like glued it on with, I don't know. But the modern design.
11:43 Chuck Nice? Chewing gum.
11:44 Neil deGrasse Tyson? A chewing gum. It's, it's integrated to the shape and the form of the wing. You'll notice that the wing continues to get narrow.
11:50 Chuck Nice? Yeah.
11:51 Neil deGrasse Tyson? To that tip, right? So it continues to get narrow, easing the air off of the tip so that you don't have this turbulent eddy. So that's, that's how you have that. So now, here's the thing. The plane wants to get airborne as quickly as possible.
12:09 Chuck Nice? Right.
12:10 Neil deGrasse Tyson? So there's a speed below which it will stall in the air and just fall out of the sky.
12:17 Chuck Nice? Okay.
12:17 Neil deGrasse Tyson? If it's going faster than that, then all the upward forces are keeping it afloat. All right.
12:23 Chuck Nice? Right.
12:23 Neil deGrasse Tyson? Like I said, less than that, you will stall and drop out of the sky. So when you hit that speed, okay.
12:32 Chuck Nice? Which I believe is eighty eight miles an hour.
12:37 Chuck Nice? I'm pretty sure.
12:38 Neil deGrasse Tyson? Yeah.
12:45 Neil deGrasse Tyson? That it should be that, even if it's not that, right? We just let it, let it be.
12:49 Chuck Nice? Yeah.
12:50 Neil deGrasse Tyson? Eighty eight miles an hour. So, um, so there's the plane. So, so you want the highest possible airspeed. The airspeed is what matters to whether you're gonna stall, right? It's how fast is the air moving over your wings? So every plane, if it has the option, is gonna take off into the wind.
13:18 Chuck Nice? Uh huh.
13:20 Neil deGrasse Tyson? Because what matters is not the speed relative to the ground. Cause a tailwind would give you high speed relative to the ground.
13:28 Chuck Nice? Mm hmm.
13:28 Neil deGrasse Tyson? But once you're airborne, you wanna stay there. And so what matters is the speed over your wings.
13:34 Chuck Nice? Over the wing.
13:35 Neil deGrasse Tyson? That the air had, and so you take, that's why every airport and aircraft carriers have at least two runways at an angle to each other. So that when the wind direction switches, they can change which runway you're using so that you will always take off into the wind.
13:56 Chuck Nice? Nice.
13:57 Neil deGrasse Tyson? And the two, the, I forgot what the, is it forty five or thirty degree angle? It's not, it's not at a ninety degree angle to each other, okay? No, because if you do, if you do the math and the geometry on this, you want it to be about a thirty degree angle. Because in all combinations, what you do is you, if you, if the wind changes direction. Then you just take off in the opposite direction of the, of the, alright? And you, it turns out many solutions are solved just by having two runways at that angle. And that's why aircraft carriers, you will see, um, just take a look at their shape. The World War II class aircraft carriers, you could, they had two angles you could land on their deck.
14:39 Chuck Nice? Right, yeah, there's, yeah.
14:40 Neil deGrasse Tyson? On it. And if you're gonna land from the direction you're coming, they would turn around the aircraft carrier so that you're coming in against the wind. So, they, you wanna take off against the wind, so this makes for a great bit of, um, for someone facing adversity in life.
14:58 Chuck Nice? Right.
14:58 Neil deGrasse Tyson? You say to them, "The airplane achieves its greatest lift when taking off into the highest headwinds."
15:10 Chuck Nice? And that notwithstanding, you are still screwed, my friend.
15:14 Neil deGrasse Tyson? You're still flucking this class. You take, go to the remedial class.
15:18 Chuck Nice? Too bad, too bad you're not an airplane.
15:23 Neil deGrasse Tyson? Don't ever be a counselor, okay?
15:27 Chuck Nice? Chuck Nice's worst life coach ever.
15:35 Neil deGrasse Tyson? Chuck, the fact that you even thought that, oh my gosh. There's some person who's got adversity in their life.
15:43 Chuck Nice? Oh.
15:46 Neil deGrasse Tyson? Too bad you're not an airplane.
15:49 Chuck Nice? Oh, well.
15:52 Neil deGrasse Tyson? Alright, so, also, um, they land into the wind, okay? Because they want their slowest possi- slowest possible speed relative to the ground.
16:05 Chuck Nice? Right.
16:05 Neil deGrasse Tyson? And that way, when they reverse the thrust of the engines, that they don't accidentally run off the end of the runway.
16:11 Chuck Nice? Right.
16:12 Neil deGrasse Tyson? So that's why planes land and take off in the same direction, often on the same runway. That's why. That's why.
16:19 Chuck Nice? That is.
16:20 Neil deGrasse Tyson? And you know how they know which way the wind's blowing? They look at the windsock.
16:23 Chuck Nice? Oh, I thought you, I was gonna say, you lick your finger.
16:26 Neil deGrasse Tyson? Oh, then they roll down the window of the seven.
16:28 Chuck Nice? Yeah, and you roll down the window of the plane, you stick your finger, okay, there we go. That's it.
16:34 Neil deGrasse Tyson? Maybe Lindbergh did that, I don't know.
16:36 Chuck Nice? Right.
16:37 Neil deGrasse Tyson? Uh, but you look at the windsocks, and I look at the windsock every single time. And I confirm that we are indeed taking off, uh, in the direction of the wind. Cause it's the opposite direction the windsock is pointing, right? You'll see next time.
16:52 Chuck Nice? You wanna go against the wind. So wherever the windsock's blowing, that ain't the way you wanna do it. That ain't the way. Real simple.
16:59 Neil deGrasse Tyson? Yeah, but you can reaffirm that, that, that the, the traffic controllers are doing the right thing.
17:05 Chuck Nice? Right.
17:06 Neil deGrasse Tyson? By making this observation.
17:07 Chuck Nice? Yeah, they're not just up there drunk and partying, you know? They actually are paying attention.
17:13 Neil deGrasse Tyson? They're also paying attention.
17:15 Chuck Nice? Well, well, that's exactly also.
17:17 Neil deGrasse Tyson? The way you said, they're not just drunk and partying. They're also looking at your ass, right?
17:21 Chuck Nice? And that's.
17:22 Neil deGrasse Tyson? So, so all this is going on, on the, on the runway. And I got more to talk about airports. I mean, I just, there's so much going on. You know why they're called?
17:30 Chuck Nice? Quick, quick, quick thing about.
17:31 Neil deGrasse Tyson? You know why they're called gates? You know why they're called gates?
17:33 Chuck Nice? Uh, uh, no.
17:35 Neil deGrasse Tyson? They used to be literal gates.
17:37 Chuck Nice? Oh, okay.
17:38 Neil deGrasse Tyson? Airports, you'd, you'd go up to the gates and they'd open the gate. And then you'd walk onto the tarmac and get on the airplane before they were jetways.
17:47 Chuck Nice? Back in the day when they had, you had to climb the stairs to get on the plane.
17:50 Neil deGrasse Tyson? Well, the president still does that when he lands in different countries, but, and, and small airports, you would do that. But I'm just saying, they were literal gates. And then we moved them indoors and now you have these jetways. You don't even see when you're, are you, am I indoors? Am I outdoors? Where am I?
18:08 Chuck Nice? Yeah.
18:08 Neil deGrasse Tyson? Well, just a reminder that it's a real object that's really flies. And thanks to engineering for this. The people that say, I don't trust science and say, it's.
18:17 Neil deGrasse Tyson? We made a 300 ton hunk of aluminum fly.
18:22 Chuck Nice? Right.
18:23 Neil deGrasse Tyson? At 550 miles an hour across country, serving you hot food and giving you the internet. While you sit in your comfortable chair. And at the end of that, you're to complain that, that the, that the salad, uh, had too much salt. That's how you know you're living in the future.
18:42 Chuck Nice? But see, the salad did have too much soft meal. I mean, I wasn't just nitpicking. Okay, I know I might seem demanding, but there is a reason behind my complaints.
18:53 Neil deGrasse Tyson? You know you're in the future, is all I'm saying.
18:56 Chuck Nice? Yeah, man.
18:56 Neil deGrasse Tyson? Anyway, planes have, there's more to talk, one day, we'll talk about the pressure difference between inside the cabin and outside. That's a fun thing. I do experiments on that. But one day, we'll do more. When you have more appetite for airplanes and airports.
19:08 Chuck Nice? I'm down with it.
19:08 Neil deGrasse Tyson? We can take this up again.
19:09 Chuck Nice? I like it.
19:10 Neil deGrasse Tyson? Uh Chuck, we gotta take a quick break, but when we come back, more of the things you thought you knew on StarTalk.
19:27 Speaker 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.
19:45 Neil deGrasse Tyson? Welcome back. We're in the middle of Things You Thought You Knew. Let's continue. Chuck, when was the last time you had an airport?
19:52 Chuck Nice? I don't know, a couple of weeks ago, a few weeks ago, maybe.
19:56 Neil deGrasse Tyson? All right, I want to give you things to notice on your next trip, because otherwise, it's just a drag to go through and TSA and everything. Just some things to notice and to think about.
20:03 Chuck Nice? You mean things like we've become a slovenly country that looks like we're going to the damn bathroom in the middle of the night when we travel? Put some clothes on, people. Real clothes. Okay?
20:16 Neil deGrasse Tyson? No, they got their pajamas on because they want to sleep on the plane. Cut them some slack.
20:20 Chuck Nice? No.
20:21 Neil deGrasse Tyson? All right, so, here you go. So, the first thing, you know, at the TSA, you got the x-ray machine, right? You got the x-ray machine. I just want to alert you of something. There was a day, and I'm old enough to remember, before anything got x-rayed. You know why? Because nobody had an x-ray machine to do it. And in the 1960s, there was a spate of hijackings. Many of them were to Cuba because we didn't, we, our diplomatic ties had been broken off. Uh, and because the Cuba were like, they were commies, right? They were sympathizers with the Soviet Union. They were in our hemisphere. And so we didn't have planes to Cuba.
21:02 Neil deGrasse Tyson? So if someone wanted to get, fly to Cuba, they had to hijack a plane. So I don't mean to laugh, but the hijackings to Cuba were like.
21:12 Chuck Nice? Right.
21:12 Neil deGrasse Tyson? So Congress said, we gotta stop this. The only way we can do it is maybe we can X-ray your luggage. Okay? So does anyone have an X-ray machine? That we can just drag in here and do this, right? That's not so large like you find in the hospital. Astrophysicists of the early 1970s had just miniaturized X-ray detectors to put into satellites to observe the universe in the X-ray part of the spectrum. Because black holes and, and matter swirling in down the throat of a black hole just before it goes to die, radiates X-rays.
21:55 Neil deGrasse Tyson? And we, we calculated this and we knew this and we said, we're going to find black holes in the universe. We need an X-ray telescope. Well, the X-ray machines are huge. We, then we gotta make them smaller to fit into the, into the, this, the, the orbit, the orbiting satellite. And so a company called American Science and Engineering, based in Cambridge, Massachusetts. Okay? Pioneered small X-ray detectors. And then they got tapped by the government and say, will you bring those into every airport in the country, every international airport? And thus was born X-ray detectors at airports because of astrophysicists.
22:35 Chuck Nice? Now, were any, were any of these astrophysicists also hijacking planes? Because I can see a connection.
22:42 Neil deGrasse Tyson? Oh, oh, the conspiracy theories, okay. And one of the leaders of that was a guy named Ricardo Giacconi. And he was also a professor, a scientist up at the Harvard College Observatory, the Smithsonian Astrophysical Observatory today, just called the Center for Astrophysics. And when I was an undergraduate there, I worked in his group, the X-ray group. We did some things, all right. And he would later be given the Nobel Prize for pioneering X-ray, opening up an entire new window on the universe, X-ray astronomy. So, and another cool thing is, I would later be tapped by the White House
23:23 Neil deGrasse Tyson? to serve on a committee to, to give out the Presidential Medal of Science, okay?
23:30 Chuck Nice? Oh.
23:30 Neil deGrasse Tyson? And this is under the George W. Bush White House. So I'm there and we get invited to the ceremony. So I'm ready to enter the White House and he's, oh, we, we awarded it to him. He'd already got the Nobel Prize. Dude, give him the Presidential Medal of Science.
23:44 Chuck Nice? Right, exactly.
23:45 Neil deGrasse Tyson? So.
23:46 Chuck Nice? Little bit of a letdown.
23:48 Neil deGrasse Tyson? Right, I know, I know. But so he comes in, and he's going through this, there's this, this house you have to walk through before you get to the White House. And that's where all the security measures are. So he's walking through and I can't help but notice the White House is using an American Science and Engineering X-ray detector.
24:07 Chuck Nice? Wow.
24:07 Neil deGrasse Tyson? Which this guy invented, it was his company. It's his company.
24:11 Chuck Nice? That's pretty cool.
24:12 Neil deGrasse Tyson? And it's what we told, we have come full circle here.
24:14 Chuck Nice? That, that's so funny is like the guy who made the thing that you're using for security is the ultimate security risk.
24:24 Neil deGrasse Tyson? Because.
24:24 Chuck Nice? Cause he knows all the back doors if there is any.
24:28 Neil deGrasse Tyson? Yeah, yeah, cause he invented, he knows what, yeah, exactly. That, that would be the case. If you're using his machine.
24:34 Chuck Nice? He'll know how to get around anything in his own inventions, you know? If, if he had come to the White House when I was head of security, I'd been like, nah, get that guy against the wall, full pat down, full pat down. That's right, everything, we gotta make sure this guy knows how to hide stuff, believe me.
24:52 Neil deGrasse Tyson? So anyway, so when you go through, they're not ASNE detectors anymore, but that was the birth of that entire movement. And it was astrophysicists. Serving our needs happened to also serve the needs of the government. By the way, I retell that story in my book, Accessory to War. The unspoken alliance between astrophysics and the military. And more broadly, it's between astrophysics and security. But anyhow, so you go through there and a lot of airports, I'd like they have mosaics in the floor. I just, and I have a little photo essay, I might publish it one day. And it's the birth of flight. It might have some rockets. It's got the night sky and it's usually some interpretation of it.
25:33 Neil deGrasse Tyson? So I, I look down as much as I look forward when I'm walking through airports, just to see what the mosaic.
25:39 Chuck Nice? Ah, the only time when you'll hear Neil deGrasse Tyson say, keep looking down.
25:43 Neil deGrasse Tyson? Yeah. So, so Chuck, so the interesting thing about X-rays, we think of them as penetrating through objects, right? Special kind of light energy. But it's not as weird as you think.
25:58 Chuck Nice? Okay.
25:59 Neil deGrasse Tyson? You realize visible light penetrates glass.
26:05 Chuck Nice? Okay.
26:06 Neil deGrasse Tyson? Okay. That's why windows are made of glass.
26:12 Chuck Nice? Okay, I mean, listen, I know that that was a scientific stretch, but uh.
26:17 Neil deGrasse Tyson? Okay, but, but wait a minute, but let's, let's keep going here. Do you know that glass blocks X-rays and high energy light? Okay?
26:32 Chuck Nice? All right, now we're doing something.
26:35 Neil deGrasse Tyson? So not all substances are transparent to all bands of light.
26:39 Chuck Nice? Okay.
26:40 Neil deGrasse Tyson? That's all I'm trying to say.
26:41 Chuck Nice? I got you.
26:42 Neil deGrasse Tyson? Okay? So microwaves, which is what your phone use to communicate.
26:47 Chuck Nice? Right.
26:48 Neil deGrasse Tyson? They clearly pass through walls.
26:51 Chuck Nice? Yep.
26:52 Neil deGrasse Tyson? Because when you go indoors, you can still use your cell phone.
26:53 Chuck Nice? I mean, unless of course you have Sprint. I mean.
26:56 Neil deGrasse Tyson? Not Sprint.
26:57 Chuck Nice? I mean, then, you know, give it up.
27:01 Chuck Nice? You know what I mean, like? Oh, my God. How would?
27:04 Neil deGrasse Tyson? If you go sprint as a sponsor of StarTalk.
27:06 Chuck Nice? Yeah, exactly. I'm roaming in the kitchen, but not in the living room? What? Okay.
27:13 Neil deGrasse Tyson? So, so, microwaves pass through walls that are otherwise opaque to you. So, the fact that X-rays go through luggage and things and human flesh, you know, you know what X-rays don't really go through? They don't really go through your bones.
27:26 Chuck Nice? I was about to say, why don't you, if you really want to fool an X-ray, just make everything out of human bones.
27:32 Neil deGrasse Tyson? No, no, no, no, no, so, no. So, it doesn't, does not go through bones. So, bones cast a shadow on what it is they're trying to view.
27:38 Chuck Nice? Ah, so, really, you're not seeing the bones themselves.
27:42 Neil deGrasse Tyson? You're not seeing the bone. You're seeing the fact that the X-ray went everywhere else except the bones.
27:47 Chuck Nice? Right. So, it's like when you stand in front of the sun and you do a puppet, you know, on the ground, a shadow puppet. You're, it's really just the, you know, the, it's not the image of your hand. It's the absence of your hand.
28:02 Neil deGrasse Tyson? Correct.
28:03 Chuck Nice? Right.
28:04 Neil deGrasse Tyson? It is, it is, it is, you're giving meaning to the absence of sunlight.
28:10 Chuck Nice? Right.
28:11 Neil deGrasse Tyson? Where your hands had blocked the photons.
28:14 Chuck Nice? Exactly.
28:15 Neil deGrasse Tyson? From hitting the sand. Right.
28:16 Chuck Nice? So, that's what, okay.
28:18 Neil deGrasse Tyson? Yeah, yeah.
28:19 Chuck Nice? That's cool, that's cool.
28:20 Neil deGrasse Tyson? When Wilhelm Röntgen discovered X-rays and he put his hand in front of it.
28:26 Chuck Nice? Right.
28:26 Neil deGrasse Tyson? And he saw that there are the, he saw the bones. He could barely see the flesh because it went right through his flesh.
28:36 Chuck Nice? Right.
28:36 Neil deGrasse Tyson? Okay? When you're looking out a window, you're not looking at the window. You're looking at what's beyond the window, okay? So, he's looking at, he doesn't see the, he sees the bones because the X-rays were absorbed by the bones. And he also think I saw his wedding ring or something, which absorbed even more X-rays. And it was like pitch black rather than sort of grayish.
28:55 Chuck Nice? And please do not ask why his wedding ring was made out of human bone.
29:01 Chuck Nice? He's a weird kinky man, that Wilhelm.
29:06 Neil deGrasse Tyson? Wilhelm Runtgen. In fact, in all the rest of the world, they call Runtgen rays rather than X-rays.
29:11 Chuck Nice? Oh.
29:12 Neil deGrasse Tyson? Yeah, yeah, yeah. So, uh, point is, uh, X-rays are useful for looking through your luggage and finding things that you might make a weapon out of, typically out of metal. But they will not find weapons made out of things that are not metal and are otherwise transparent to plastic, like, um, a plastic gun.
29:33 Chuck Nice? Right.
29:33 Neil deGrasse Tyson? If you make a plastic gun, it's not, it's not gonna find it in the same way it would reveal a, a, uh,
29:41 Chuck Nice? A regular metal gun.
29:42 Neil deGrasse Tyson? So.
29:42 Chuck Nice? Big time, big time controversy on that too, about printable guns.
29:47 Neil deGrasse Tyson? Correct, correct. So, here's an interesting thing you can do. Uh, like I, like you said, like I noted, um, the bone does not completely block the X-rays. It just blocks more X-rays than your flesh does. So it casts its own mild shadow in the photograph. Okay. If you have different frequencies of light and you interplay them, you can see what the trend line is in the thing's attempt to absorb it or not.
30:23 Neil deGrasse Tyson? And once you do that, you're better at detecting what could be in the suitcase. If you move the frequencies back and forth. But what they also do is, they attach color. This is the literal use of false color. Where you attach a color to the edges of signals that are shown up in the image, in the X-ray image. Because your eye picks up color much better than it picks up, uh, tiny changes in, in a grayscale shading.
30:52 Chuck Nice? Right.
30:52 Neil deGrasse Tyson? All right. So if I say, anything grayer than this level, make it red. Anything less gray than that, make it blue. Your eye pip, boom. I see red and blue as two completely separate things, rather than as the continuum that it is. So. The folks back there, the TSA, they have a fascinating task ahead of them to identify objects and shapes and
31:20 Chuck Nice? Right.
31:20 Neil deGrasse Tyson? And, and, and highlight them in ways that it makes it easy for the person looking through, looking at your luggage rather than harder.
31:28 Chuck Nice? Right. And so, yeah, yeah, that's, that's super cool. And I wondered, do they assign a special color to sex toys? Because they tend to somehow find them all the time.
31:42 Neil deGrasse Tyson? I've never seen this ever happen. Is this you trying to pull sex toys through the security?
31:48 Chuck Nice? I'm just saying, I don't know how every time it, you know.
31:51 Neil deGrasse Tyson? You heard that this happened.
31:53 Chuck Nice? That's what I hear, that somehow they're just like, gotta check that one. And it's just like, nope, just another sex toy. Sorry, everyone, everything's great. All good. This guy.
32:04 Neil deGrasse Tyson? No reason to be alarmed.
32:05 Chuck Nice? This guy right here.
32:05 Neil deGrasse Tyson? Just another tech sex toy.
32:06 Chuck Nice? So you're free to go with your sex toy.
32:09 Neil deGrasse Tyson? And by the way, those, the, those flappy things at the entrance where your luggage into the machine?
32:16 Chuck Nice? Yes.
32:16 Neil deGrasse Tyson? They're like, have heavy metal particles in them. So the X-rays don't come out. So don't reach in there because it's trying to shield you from the X-rays that would otherwise leak out of that hole.
32:27 Chuck Nice? Nice.
32:29 Neil deGrasse Tyson? There, there you go.
32:30 Chuck Nice? Well, that is, I, I have to tell you, I will never look at the X-ray machine again the same way.
32:38 Neil deGrasse Tyson? This is what I'm saying. And I want you to think of astrophysicist when you do.
32:41 Chuck Nice? And I, I will now, which I have never done before. I can say that with a.
32:48 Neil deGrasse Tyson? X-rays are just another band of light that comes to us from the depths of space that humans on earth with excellent engineering has exploited for all manner of social, cultural, geopolitical purposes.
33:01 Chuck Nice? Look at that. Thank you, Wilhelm.
33:04 Neil deGrasse Tyson? Time for a break, but when we come back, we will continue stuff you thought you knew.
33:21 Neil deGrasse Tyson? We're back. One of my favorite segments, Things You Thought You Knew. Uh, let's continue. Chuck, I got some more explaining to do.
33:28 Chuck Nice? Ah.
33:30 Neil deGrasse Tyson? Okay.
33:32 Chuck Nice? I feel like that's... I feel like, uh, I don't know. Lucy. Was that...
33:38 Neil deGrasse Tyson? Oh, Lucy.
33:40 Chuck Nice? Lucy, you got some explaining to do.
33:42 Neil deGrasse Tyson? Yeah, yeah. So, so, we... Some long ago, sometime, I think we talked about the rocket equation. I want to talk about that again, but then take us into space with it and talk about some other stuff as well. Okay, so you ready?
33:56 Chuck Nice? All right.
33:57 Neil deGrasse Tyson? So, here you go.
33:58 Chuck Nice? Blast off. There you go.
34:00 Neil deGrasse Tyson? Mm-hmm. All right. So, if you're gonna drive from New York to California...
34:04 Chuck Nice? Right, which I'm never gonna do.
34:05 Neil deGrasse Tyson? And you have... No, and you have been... And you have an internal combustion engine car. Right. They're called ICE cars, in the lingo, by the way. Uh, internal combustion engine. You fill up the tank with gas.
34:18 Chuck Nice? Right.
34:18 Neil deGrasse Tyson? Until it's empty.
34:19 Chuck Nice? Right.
34:20 Neil deGrasse Tyson? And then you fill it up again.
34:21 Chuck Nice? Correct.
34:21 Neil deGrasse Tyson? And then you fill it up again, till you... Till you get to California.
34:24 Chuck Nice? Right.
34:24 Neil deGrasse Tyson? You have convenient filling stations along the way.
34:27 Chuck Nice? All along the way. Just little daggers in the heart of the earth, all along the way.
34:31 Neil deGrasse Tyson? Now, if you didn't have those...
34:34 Chuck Nice? Right.
34:35 Neil deGrasse Tyson? You would need a single tank, big enough, to get you to California.
34:39 Chuck Nice? Yeah.
34:40 Neil deGrasse Tyson? A single tank.
34:41 Chuck Nice? Right.
34:42 Neil deGrasse Tyson? So, we have to ask, what does that tank weigh?
34:47 Chuck Nice? Right.
34:48 Neil deGrasse Tyson? Now, if that tank weighs as much as the car, and then some, maybe...
34:55 Chuck Nice? Mm-hmm.
34:55 Neil deGrasse Tyson? Then the fuel you're burning in New York, part of that is just simply to move the car that's filled with fuel you haven't burned yet.
35:05 Chuck Nice? Right. Exactly.
35:07 Neil deGrasse Tyson? Such is the challenge with rockets.
35:11 Neil deGrasse Tyson? Because we don't have filling stations in space. Every ounce of fuel you burn is to get the next ounce of fuel higher up. So that it could then burn afterwards. Okay, so let's, let's run a quick mathematical example. You ready?
35:29 Chuck Nice? Okay.
35:30 Neil deGrasse Tyson? If I tell you it takes one pound of fuel.
35:32 Chuck Nice? Okay.
35:33 Neil deGrasse Tyson? To put one pound of payload into orbit. You ready? Okay, you got that?
35:38 Chuck Nice? Right, right.
35:39 Neil deGrasse Tyson? Okay, you with me?
35:40 Chuck Nice? Okay.
35:41 Neil deGrasse Tyson? Stay with me.
35:41 Chuck Nice? One pound of fuel.
35:42 Neil deGrasse Tyson? One pound of fuel.
35:43 Chuck Nice? For one pound of payload.
35:44 Neil deGrasse Tyson? To put one pound of payload into orbit. Alright, suppose I want to put two pounds of payload.
35:50 Chuck Nice? I'm gonna need two pounds of fuel.
35:53 Neil deGrasse Tyson? No.
35:55 Neil deGrasse Tyson? You're gonna need a pound of fuel for each of those pounds.
36:00 Chuck Nice? I need the fuel for the fuel. I need fuel for the fuel. Damn, that's right. For the fuel. So I need a pound of fuel for the pound, a pound of fuel for the fuel.
36:13 Neil deGrasse Tyson? For the fuel, okay? So now that's three pounds of fuel.
36:17 Chuck Nice? Fuel, right.
36:18 Neil deGrasse Tyson? To put.
36:18 Chuck Nice? To get one.
36:19 Neil deGrasse Tyson? Two pounds into orbit.
36:20 Chuck Nice? Two pounds, right.
36:21 Neil deGrasse Tyson? Now let's go three pounds of payload. Okay?
36:25 Chuck Nice? Right.
36:26 Neil deGrasse Tyson? So there's a pound each for each of those, that's three pounds.
36:32 Chuck Nice? Right.
36:33 Neil deGrasse Tyson? Okay? Plus a pound of fuel for each of those three pounds of fuel.
36:39 Chuck Nice? So I need, yes.
36:40 Neil deGrasse Tyson? That's six. Okay, but wait. Then, am I saying this right now? Then you need a pound of fuel.
36:53 Neil deGrasse Tyson? For the fuel that's gonna get the three pounds of fuel into orbit. The point is.
36:58 Chuck Nice? That's right.
36:59 Neil deGrasse Tyson? Whether or not I even explained that accurately. But you get the point here. The point here is that the amount of fuel you need for every increment of payload grows exponentially.
37:13 Neil deGrasse Tyson? And it's a famous equation called the rocket equation.
37:17 Chuck Nice? Right.
37:17 Neil deGrasse Tyson? That's why if you saw the launch of of either Apollo missions, if you're an old timer, or the recent
37:24 Chuck Nice? Artemis.
37:24 Neil deGrasse Tyson? Um Artemis missions.
37:26 Chuck Nice? Right.
37:27 Neil deGrasse Tyson? You see this huge rocket. And what the top is the Orion capsule.
37:33 Chuck Nice? Right.
37:34 Neil deGrasse Tyson? Service module and the capsule. It's way it's the little thing at the top.
37:38 Chuck Nice? Right.
37:38 Neil deGrasse Tyson? Everything else is fuel because that has to go not only to Earth orbit, but to the moon and back. And the astronauts are the payload plus whatever the hell else they've taken up there. So the rocket equation, you need calculus to do that correctly. So the so a more realistic calculation would be uh 10 pounds of fuel for one pound in orbit of payload, right? That's more realistic. So now two pounds is one is you need 10 pounds for that extra pound of fuel plus 10 pounds of fuel for the 10 pounds of fuel they got the other pound of fuel.
38:19 Chuck Nice? Crazy.
38:20 Neil deGrasse Tyson? So it's crazy. It's completely crazy. Okay, so now here's an interesting fact. Okay, when you burn your gasoline, okay, uh it it uh how does it turn into energy? You remember?
38:33 Chuck Nice? Um, there's a small spark that turns into an explosion that pushes a piston.
38:37 Neil deGrasse Tyson? It's a spark.
38:38 Chuck Nice? Right.
38:39 Neil deGrasse Tyson? Correct, and the explosion is the gasoline plus what?
38:45 Chuck Nice? Um, they infuse it with air or something to like it's a it becomes a few air.
38:51 Neil deGrasse Tyson? In the air that
38:53 Chuck Nice? Oxygen.
38:53 Neil deGrasse Tyson? Yeah, yeah, so the air, what's in the air? Oxygen, thank you. So you have gasoline plus oxygen makes energy. Okay, when it burns.
39:01 Chuck Nice? Gotcha.
39:02 Neil deGrasse Tyson? You got the oxygen for free.
39:06 Neil deGrasse Tyson? It's just sitting there in the air.
39:09 Chuck Nice? Right.
39:10 Neil deGrasse Tyson? Okay, if I have a rocket, I want it to leave the air.
39:17 Neil deGrasse Tyson? If I'm leaving the air, I don't have oxygen.
39:19 Chuck Nice? Oh, no.
39:20 Neil deGrasse Tyson? I have to bring the oxygen with me.
39:23 Chuck Nice? Well, this is getting more expensive all the time.
39:31 Neil deGrasse Tyson? Okay, so here you go. So the, do you remember the Artemis and the space shuttle? Has two solid rocket boosters on the side.
39:41 Chuck Nice? Right.
39:42 Neil deGrasse Tyson? The two boosters, and then it releases them.
39:45 Chuck Nice? Right.
39:46 Neil deGrasse Tyson? Those two boosters burn air with their mixture.
39:52 Neil deGrasse Tyson? When the rocket gets high enough, they're done. We can't have them trying to work where there's little air, because what's the point of that? So you get to use the free air to launch the rocket at its lowest level through the atmosphere, where there's plenty of oxygen.
40:08 Chuck Nice? Right.
40:09 Neil deGrasse Tyson? Then they drop away, and anything that happens after that needs its own oxidizer. And the fuel tanks that not only started burning at the base on the launch pad, but continue in orbit is the larger tank that has two tank containers. One of them holds hydrogen, the other holds oxygen. And the hydrogen tank is twice as big as the oxygen tank.
40:37 Chuck Nice? Okay.
40:37 Neil deGrasse Tyson? So when I mix them, what's the mixture?
40:41 Chuck Nice? That sounds a little bit. Sounds a little bit like H2O.
40:46 Neil deGrasse Tyson? Oh. Well, yes. So when I mix hydrogen and oxygen, it is highly exothermic, meaning it releases tons of energy. And the, and the, and the exhaust is water.
41:03 Chuck Nice? Oh, wow.
41:04 Neil deGrasse Tyson? Water.
41:06 Chuck Nice? So, so, so we have this incredible, you know, propellant that the byproduct is water.
41:17 Neil deGrasse Tyson? Yes.
41:18 Chuck Nice? Why doesn't everything run on that?
41:26 Neil deGrasse Tyson? I love the gears are going in Chuck's head.
41:31 Chuck Nice? I'm just saying.
41:32 Neil deGrasse Tyson? Okay, okay, okay. There isn't hydrogen just laying around.
41:38 Chuck Nice? Ah, I got you.
41:40 Neil deGrasse Tyson? But it's everywhere in water, but pure hydrogen is just so you have to get the hydrogen. So you're gonna get it from the water to begin with. And guess how much energy it takes to separate the H2 from the O?
41:54 Chuck Nice? More than it does to put a rocket.
42:02 Neil deGrasse Tyson? So the energy it takes to separate the hydrogen oxygen is slightly more than you're gonna get back by recombining the hydrogen and the oxygen.
42:10 Chuck Nice? I see.
42:12 Neil deGrasse Tyson? Yeah, that's so. It's not quite an equal thing, but that's how you get your hydrogen fuel. It sucks. It totally sucks. And where are you gonna get that energy from? Is it a oil plant or whatever? You know, you can use solar power to do that, by the way. And so, but I'm just saying, there's no such thing as a free lunch.
42:34 Chuck Nice? There you have it.
42:36 Neil deGrasse Tyson? There you have it. So the, and by the way, they use liquid hydrogen and liquid oxygen. Because that's it's much denser. You get way more fuel than if it's just gaseous hydrogen and gaseous oxygen. But liquid hydrogen is liquid at like four, is that? I forgot the number, but low, single-digit Kelvin temperature.
42:55 Chuck Nice? Oh, wow.
42:56 Neil deGrasse Tyson? Okay, we got a whole other explainer on Kelvin, low, single digits. So the, the whole thing is chilled. And that's why you look at some launch videos of, of the Saturn V rocket, you see this ice rolling off the sides.
43:12 Chuck Nice? Yes.
43:12 Neil deGrasse Tyson? It's Florida. Where the hell's the ice come from? Because this stuff is cold, all right? Keeping liquid oxygen and liquid hydrogen so that when they combine, you have the maximum number of molecules to do it. Get the maximum amount of exothermic reaction and you get the maximum thrust. And according to Newton, you cannot move forward unless you spew something else back out the other side.
43:38 Chuck Nice? Normally for me, it's hatred.
43:41 Neil deGrasse Tyson? Hey.
43:42 Chuck Nice? Yeah.
43:43 Neil deGrasse Tyson? I'm glad you said that instead of flatulence.
43:47 Chuck Nice? That was my first thought, but I was like, ah, let's go.
43:49 Neil deGrasse Tyson? That was your first thought, right?
43:50 Chuck Nice? I was like, let's go a little deeper.
43:51 Neil deGrasse Tyson? Let's get, let's be a little more mature.
43:53 Chuck Nice? Yeah.
43:54 Neil deGrasse Tyson? Yeah, okay. So, the point is, unless you have friction to help propel you forward, if you're just trying to move through the, through space or through the air, something has to come out the back. So that you propel forward. For every action is an equal and opposite reaction.
44:12 Chuck Nice? Reaction.
44:12 Neil deGrasse Tyson? And that's why you have this huge plume coming out the other side. And so this, that's the rockets 101 for you.
44:21 Chuck Nice? That's very cool.
44:21 Neil deGrasse Tyson? Just saying.
44:22 Chuck Nice? That is cool. Well.
44:24 Neil deGrasse Tyson? Very cool. And all that began like in the early 20th century. So the Russian who did this early 20th century is Sokolsky. I always mangle the name. Silikovsky. There we go.
44:35 Chuck Nice? Yeah.
44:35 Neil deGrasse Tyson? I think I did that right. He first wrote down the rocket equation and Russia didn't look back.
44:40 Chuck Nice? Uh huh.
44:40 Neil deGrasse Tyson? And so the Russians had the rocket equation. They had Sputnik. They had Leica, the first mammal. They had the first astronaut. So they beat us at everything except for landing on the moon.
44:52 Chuck Nice? Ah, you know, that's.
44:53 Neil deGrasse Tyson? We landed, we say we win.
44:54 Chuck Nice? Of course.
44:55 Neil deGrasse Tyson? They beat us at everything else. All right. So this has been another Star Talk, Things You Thought You Knew Edition. I thank my co-host Chuck. It was a pleasure. I'm Neil deGrasse Tyson. As always, I bid you to keep looking up.
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