Things You Thought You Knew – What is Energy?

How is energy different from matter? Neil deGrasse Tyson and comedian Chuck Nice break down what energy is and where it comes from, ancient theories about sight, and how wheels keep us moving. Explore physics, thermodynamics, and more!

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

• 0:00Neil deGrasse Tyson?

  Chuck is smoking something.

• 0:06Chuck Nice?

  I'm just saying. I'm ready to talk about this all day.

• 0:11Neil deGrasse Tyson?

  Chuck is smoking, but wait, there's more.

• 0:16Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk, Things You Thought You Knew Edition. So I was just thinking, how much we take for granted about when we use the word energy? And it has profound origins. When our understanding of energy has profound origins. The brilliance of Isaac Newton, who, you know, discovered the laws of optics and gravity and motion and invented calculus.

• 1:00Neil deGrasse Tyson?

  Energy was not a fully developed concept in his time. And so, so I just want to sort of spend a few minutes offering an appreciation for a triumph of the human intellect to figure out what the hell energy is and then how to manufacture it and exploit it. I just want to spend a few minutes. This is like a public service announcement for energy. So, uh, energy is not a thing, right? You can say a rock is a thing and you can point to it or planet is a thing. And energy is not a thing.

• 1:42Neil deGrasse Tyson?

  So it was delayed in our ability to understand what it was and how to think about it. So we knew some things. For example, when you had a cannon, back when cannons were like a popular tool in warfare.

• 2:01Chuck Nice?

  Right.

• 2:01Neil deGrasse Tyson?

  There were physicists at the time who said, hmm, I have a cannonball and have this gunpowder and the cannon is made of iron. Then I fire it and if I keep doing this, the cannon gets hotter and hotter. Well, where's that heat coming from? So what is it? And so in the urge to turn energy into a thing, early ideas was that there was, energy was a fluid, was a thing that could move in and out of objects. Okay, one of them, they called it phlogiston. Another one was a caloric.

• 2:46Neil deGrasse Tyson?

  These were words invented to try to think about energy as an, as a thing. And it moves and it's got to be somewhere and, and so a hot cannon had more of this in it than a cold cannon. And so, and so there was, you had to start somewhere. We were crawling before we even could walk. And it wasn't until we understood molecules and atoms and, and that we were able to say, hmm. Okay, and, and what role friction plays in this, we're able to say, hmm. So you can store energy in different ways.

• 3:31Neil deGrasse Tyson?

  And when you store it, it's not manifesting itself. It's like saying, here I am, look, it's not really doing that. Mm hmm. And when you're storing it, no, the object is not in motion. No, the object is not, you know, it's not all these things that it is when it's manifesting. So let's take the simplest case, a roller coaster. Okay. Right. Every roller coaster, the first ascent

• 4:00Neil deGrasse Tyson?

  is the highest. Yeah. Okay. So what's going on? So there you go. And you're leaning back and this thing cranks you up. It is endowing you with energy. Potential energy. Spared energy.

• 4:19Neil deGrasse Tyson?

  Potential gravitational energy. When you get to the top, you can calculate how, because we have formulas for this, calculate how much gravitational energy it handed you. So I don't feel this energy. I don't know what you're talking about. Until I push you over that ledge.

• 4:36Chuck Nice?

  Right.

• 4:37Neil deGrasse Tyson?

  Over the other side of that hill. Then what happens is your potential energy starts converting to kinetic energy. And it's an exact trade off. An exact trade off. So all that energy they gave you at the top.

• 4:55Chuck Nice?

  Right.

• 4:56Neil deGrasse Tyson?

  Okay, now is return with you speeding up as you descend.

• 5:01Chuck Nice?

  And that is when the ham sandwich becomes actual vomit.

• 5:08Neil deGrasse Tyson?

  Okay.

• 5:13Neil deGrasse Tyson?

  That's a transformation of another kind, right?

• 5:20Neil deGrasse Tyson?

  Um, so, and it's this trade off. And it goes back and forth as you go up hills and down. If you go up a shorter hill than the first one. Okay, you have enough energy to reach the top of that hill. Because you started out with way more energy than that at an even higher hill. You're gonna lose some energy to friction. Okay, so in other words, you can't ascend back to a hill exactly the same height that you started in. Okay, some energy will go to friction. And when you lose energy to friction, that makes heat. Okay, that's the source of heat. When you lose energy. Alright, so that's why the engine of your car gets hot.

• 6:02Chuck Nice?

  Right.

• 6:02Neil deGrasse Tyson?

  Okay, not all the energy that you started with got transferred to the motion of the car. The losses went to friction. The friction heated your engine. Your engine gets hot. Okay, so in a roller coaster, you're converting gravitational potential energy to kinetic energy and back and forth and back and forth and back and forth. And if they designed it right. The frictional energy that you lose, okay? You don't go up higher and higher. The hills you go over have to get lower and lower. And there's the last one, then you come in for the stop.

• 6:33Chuck Nice?

  Right.

• 6:34Neil deGrasse Tyson?

  So they, they gave you the energy when you started at the top of that hill. So that's gravitational potential energy becoming kinetic energy. That, that's what's going on there. And like I said, if you go back up a shorter hill, you'll slow down.

• 6:50Chuck Nice?

  Mm hmm.

• 6:51Neil deGrasse Tyson?

  Because some of that kinetic energy is giving back to you. So you can have another little lump of, of potential energy to take the next hill that comes after that. All right. So that's easy. We've had roller coasters forever. You could have imagined them forever ago. But it's more complicated or a little more physics involved. If you want to say this molecule has energy.

• 7:15Neil deGrasse Tyson?

  A molecule. Well, how am I going to get the energy out of the molecule? You're just sitting there. Oh, well, you can, in one case, burn it. Burn the molecule. Okay. Why is it that you can throw a log in the fire? And the log is room temperature. You put in the fire, then the fire ignites the log and the log keeps burning. There's, there's chemical potential energy in the molecules of the log. Where did that energy come from? Where did the log get that energy, Chuck? You tell me right now.

• 7:53Chuck Nice?

  The log is, it's, it's from its molecules. It was storing.

• 7:57Neil deGrasse Tyson?

  Where did its molecules get their energy?

• 8:01Chuck Nice?

  Okay, let me think about this.

• 8:05Chuck Nice?

  Oh, from their atoms?

• 8:11Neil deGrasse Tyson?

  What did the log used to be?

• 8:13Chuck Nice?

  No, it used to be a tree.

• 8:15Neil deGrasse Tyson?

  A tree? How does a tree get energy?

• 8:17Chuck Nice?

  Um, from the sun.

• 8:19Neil deGrasse Tyson?

  Thank you. Thank you.

• 8:23Neil deGrasse Tyson?

  This, the sun builds molecules that contain stored energy. So that's why wood burns. Because it has stored chemical energy given to it by the sun.

• 8:37Neil deGrasse Tyson?

  And it's just sitting there minding its own business. But that's why fires in homes are so deadly. Because this all this potential energy stored in the molecules of organic matter, wood. If your house is made of wood. So that the whole thing burns. Converting the chemical, the chemical energy into thermal energy.

• 9:02Neil deGrasse Tyson?

  So so much of our lives is the conversion of energy of one form into another. And what happens while that's going on? So other forms of energy, there's energy in the nucleus of an atom.

• 9:17Chuck Nice?

  Yes.

• 9:17Neil deGrasse Tyson?

  You split the nucleus and take it out, we make bombs doing that. Okay, so we turn nuclear energy into the kinetic energy of an explosion. To do damage to things in warfare. Okay, that's nuclear or chemical energy. Some chemicals will give you their energy, not slowly, like a slowly burning log. They'll give it to you catastrophically. All right. And we call those bombs. Okay, or a firecracker catastrophically boom. The energy goes to break apart, the firecracker goes into the sound. That it makes the shockwave, all of that.

• 10:01Neil deGrasse Tyson?

  So our lives and everything we do. Is nothing but a ballet of the conversion of energy from one form. Into another. So when we consume food that has calories. A one for one definition of calorie is energy. So you eat food that has, you look at the calorie content, that's how much energy it has. Okay, so then you consume it. You need energy to live, to move, your heart beats, all this requires energy. You're getting it from the calories of the food you eat. So what happens if you consume more calories than you need? Your body says, store that.

• 10:45Neil deGrasse Tyson?

  So it creates, it creates chemical potential energy in the form of fat. And it stores it away.

• 10:53Chuck Nice?

  I'm not fat, I'm just filled with potential.

• 11:00Chuck Nice?

  What you talking about? You see this? This is potential. I am potentially Michael B. Jordan. I am potentially Michael B. Jordan. That's what the potential.

• 11:18Neil deGrasse Tyson?

  My six pack is just beneath the potential.

• 11:24Chuck Nice?

  You don't even know what you can have.

• 11:26Neil deGrasse Tyson?

  And by the way, that conversion of your body's calories to your energy is not perfectly efficient. So what happens to that excess energy that's not converted? It's that's the inefficiency of your body. All it we're an engine of sorts. It's inefficient. So that inefficiency gets converted to heat. So your body heats up when you exercise. That's it's a consequence of the inefficiency of your body. But your body loves that because now you you it's part of your temperature regulating system. But I'm just saying you when you exercise, your body heats up in the same way you drive a car. The car heats up in the same way.

• 12:07Neil deGrasse Tyson?

  The the wheels and the tracks of a roller coaster are actually getting hot because of the inefficiencies of the conversion because there's inefficiencies in every conversion of energy from one form to another. So the only point of this is just to say so much of what we do and how we live involves the clever conversion of energy from one form to another. Nuclear energy, chemical energy, which is molecular. Uh, we have kinetic energy, gravitational energy. All of this comes together and our ability to exploit that in the service of civilization is one of the great triumphs of physics, especially 19th century physics,

• 12:53Neil deGrasse Tyson?

  where they figured out, oh, my gosh, look what we can do. Another quick one, just look a locomotive, right? Well, what's going on there? Well, the locomotive, all right? I don't know if you remember, they'd have to fill up with some water tanks every now and then. Okay, well, what does the water do? Well, a locomotive burns either coal or wood.

• 13:15Neil deGrasse Tyson?

  And it heats a, so that's the chemical energy. It heats a vat of water. So it's got the stored chemical energy of the wood into the active thermal energy of the vibrating water molecules. They then evaporate, creating pressure for the steam to then move wheels to have the locomotive go forward. Oh my gosh. And that all started with solar energy. That made the wood or the coal that made the, uh, the, the fire that made the boiling water that made the pressure that moved the wheels. All of this is a triumph of our understanding of energy.

• 13:58Chuck Nice?

  Now, what you just said there, I can hear Exxon going, listen, guys, we're actually solar energy. Okay.

• 14:09Chuck Nice?

  We got, I just see it coming down.

• 14:12Neil deGrasse Tyson?

  Ultimately.

• 14:13Chuck Nice?

  Ultimately, guys.

• 14:14Neil deGrasse Tyson?

  It started as solar energy.

• 14:15Chuck Nice?

  This is solar energy, okay?

• 14:16Neil deGrasse Tyson?

  Muscle fuel started as solar energy. This is true. This is true. It reminds me of this bumper sticker. It says no nukes, right? From the anti-nuke movement. And then the O in the no is an image of the sun. It says no nukes.

• 14:34Chuck Nice?

  No nukes. Okay, yeah, exactly.

• 14:36Neil deGrasse Tyson?

  I know what they mean. They want you to do solar energy, but the sun makes us energy with nukes. All right? Just like, make that clear here. That's how that, it started that way. So anyhow, I just thought I'd put all that out there. And so to, just to enhance our appreciation for what energy does for us and how being clever has enabled us to build civilization on the exploitation of converting energy from one form into another.

• 15:07Chuck Nice?

  Yeah. It has built civilization and ultimately it will destroy civilization.

• 15:15Neil deGrasse Tyson?

  On that happy note. Thank you.

• 15:25Speaker 02

  I'm Joel Cherico and I make pottery. You can see my pottery on my website, cosmicmugs.com. Cosmic Mugs, art that lets you taste the universe every day. And I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 15:46Neil deGrasse Tyson?

  Doc, what do you know about Medusa?

• 15:49Chuck Nice?

  Um, I don't want to see her, uh, know that.

• 15:56Chuck Nice?

  If, if she ever said to me, uh, "Look here," I'm like, "No."

• 16:01Neil deGrasse Tyson?

  Not looking.

• 16:03Chuck Nice?

  No, I'm not looking. What you mean, "Look here"?

• 16:08Neil deGrasse Tyson?

  Yeah, she makes eye contact with you, you turn to stone.

• 16:11Chuck Nice?

  Right.

• 16:12Neil deGrasse Tyson?

  She's famously in the night sky. She's immortalized. The severed head of Medusa is immortalized, held by the Perseus. Perseus is a constellation in the sky. And there's a star called Algol, which is a variable star. It changes its brightness, um, over relatively short periods of time. That's why we call them variable stars. And the eye of the severed head is Algol. So this is Medusa, like, looking at you. It's pretty fun. And of course, Perseus was the hero in the story with Andromeda, who is the daughter of Cassiopeia.

• 16:50Neil deGrasse Tyson?

  And she was, I don't remember why, oh, Cassiopeia said she was more beautiful than the sea nymphs. And then, then out of punishment, they took her daughter and strapped her to the cliffs for the sea monster. Perseus comes to save, to save her. He has to slay Medusa, alright? And so, he does it by looking at her, but through the reflection of his shield.

• 17:18Chuck Nice?

  Right.

• 17:19Neil deGrasse Tyson?

  And that way, it's not a direct... Direct sightline.

• 17:23Chuck Nice?

  I can't believe she fell for that.

• 17:25Neil deGrasse Tyson?

  And fell for that, you know, and backs up to her and slays her backwards, right?

• 17:30Chuck Nice?

  Right.

• 17:30Neil deGrasse Tyson?

  Pretty cool. And it cuts off her head and puts it in a, in a, in a sack. Perseus is in the sky, um, rides on the back to go save Andromeda by showing the severed head of Medusa to the kraken and the kraken turns to stone and then crumbles away because he's too big to be stone, right?

• 17:50Chuck Nice?

  I was, I was, I gotta say, that's a big chance that Perseus took that, you know, the severed head would still be able to do its thing.

• 17:59Neil deGrasse Tyson?

  Good, yeah, yeah. Rather than just with closed eyelids, right?

• 18:02Chuck Nice?

  Right.

• 18:02Neil deGrasse Tyson?

  You have to like pry open the eyelids with toothpicks or something to make that happen.

• 18:05Chuck Nice?

  Exactly. Cause you know, a lot of times, you know, he had to make sure she died with her eyes open. Probably from the surprise, the surprise of falling for that stupid trick of looking at her through a shield. So she died with her eyes like, I can't believe that I fell for this, like.

• 18:25Neil deGrasse Tyson?

  That what she sounds like?

• 18:27Chuck Nice?

  That's Medusa. I can't believe, I can't believe I fell for this stupid trick.

• 18:35Neil deGrasse Tyson?

  So, okay. So all of them are in the night sky. We got Andromeda, Medusa, uh, Cassiopeia. Uh, the reason why I'm saying all this is there's a whole set of legends that derive from the expectation that when you look at someone or anything, that you're sending out some beam of energy or information or light as though seeing was an active aspect of what it is to obtain information.

• 19:08Chuck Nice?

  Right.

• 19:08Neil deGrasse Tyson?

  So I see you because, because I'm going out there and I'm getting you and bringing you back into my head.

• 19:15Chuck Nice?

  Right.

• 19:16Neil deGrasse Tyson?

  Right, right. So that is not how seeing works. And this was not established until about 1300 years ago in the Middle East, in what we said called the golden age of Islam, uh, Al-Hazm. Uh, occasionally referred to as Al Haytham, both of those I think are legitimate names for him. One of the great scientists of the era, an early scientist in the history of scientists. Um, kept good notes, had hypotheses of how things worked. He looked at a cow eyeball, saw a lens, saw that you can make an image on the back of the eyeball. And he deduced that the act of sight is 100% passive.

• 20:01Chuck Nice?

  All reception.

• 20:03Neil deGrasse Tyson?

  All reception. So you can't just give someone the Google eyes and have them say, oh, I feel someone's looking at me. People will still say that. But all experiments show that, no, you cannot tell if you do it in a controlled setting. You cannot tell when someone's looking at you.

• 20:19Chuck Nice?

  Unless you're in the subway. Cause sometimes you're in the subway and you just get that feeling that comes up the back of your neck. And you turn and there is some creepy person staring at you. And they don't turn away. They will not. That's how you know you're in New York. Any other place, you look at somebody and they look away like, oh, shoot, I was staring.

• 20:41Neil deGrasse Tyson?

  They look sheepish about having been caught.

• 20:43Chuck Nice?

  I can't believe I was there. In New York, you turn at them and they're just like, that's right. I'm going to kill you. Like.

• 20:54Neil deGrasse Tyson?

  Don't scare people from the New York City subways. That's not what. Here's my point. Anytime you turn around because you think someone's staring at you and they are staring at you.

• 21:03Chuck Nice?

  Right.

• 21:03Neil deGrasse Tyson?

  You have not recorded the thousands of times people were also staring at you. And you didn't turn around to notice. Okay? So this, this is when you do the control setting, this, this is the case. So it's just an interesting fact. The Bible stories about, who was it that turned back and she became a pillar of Saul?

• 21:22Chuck Nice?

  Lot's wife. She observed the destruction of Sodom and they were told, whatever you do, do not look back.

• 21:30Chuck Nice?

  And so she violated the directive, looked back at the destruction and turned to stone in doing so.

• 21:37Neil deGrasse Tyson?

  Okay, so that case, that might not be her sending out a signal from her eyeball. So that sounds like a more legit, uh, consequence of this.

• 21:45Chuck Nice?

  Right.

• 21:45Neil deGrasse Tyson?

  Relative to Medusa looking at you.

• 21:48Chuck Nice?

  Right.

• 21:49Neil deGrasse Tyson?

  Her eyes light up and then you turn to stone. So, so I just, it's an interesting history, how you can, there, there can be mythologies that rise up around physiological misconceptions that make for interesting stories, right?

• 22:04Chuck Nice?

  Right.

• 22:04Neil deGrasse Tyson?

  And people used to be thought of as dying of a broken heart, alright? Uh, maybe it was an actual heart attack, alright? But, and, you know, there.

• 22:14Chuck Nice?

  It was bacon, it was bacon.

• 22:17Neil deGrasse Tyson?

  But Francis Bacon?

• 22:18Chuck Nice?

  No, it was just bacon.

• 22:20Neil deGrasse Tyson?

  Bacon ate.

• 22:21Chuck Nice?

  That's just, like, he died of a broken heart, no. No, that's called cholesterol. That's called cholesterol. The man had bacon with every single meal. And you know, you can't do.

• 22:33Neil deGrasse Tyson?

  But, you can't, you don't want to take away the romance of dying of a broken heart, that's all.

• 22:39Chuck Nice?

  No.

• 22:39Neil deGrasse Tyson?

  So it's just, it's just fun, so I don't, I don't object to misconceptions if you have no better explanation at the time. And it becomes part of a, sort of our cultural sense of the world. I mean, that's, this is what, um, this is the richness and the depth of history that we experience as a culture. Who knows what they'll be saying about.

• 22:59Chuck Nice?

  Here's, here's the problem with that, though.

• 23:02Neil deGrasse Tyson?

  What?

• 23:03Chuck Nice?

  Someone of your particular acuity can say that. Can say, this is part of the wondrous romance of life.

• 23:15Neil deGrasse Tyson?

  Charming elements of our.

• 23:16Chuck Nice?

  The charming elements of life that we're able, because you're a person who understands the scientific method. You're somebody who, uh, uh, you know, believes in data and empiricism, you know, both.

• 23:30Neil deGrasse Tyson?

  Mm-hmm.

• 23:30Chuck Nice?

  Okay. But the problem with that, that charming, that wonder, that, you know, these, these, these idiosyncratic, you know, things that happen, um, that we attribute meaning to them, you know that we're attributing that meaning. We are affixing meaning to those things. They don't really have meaning. The problem is, there are a bunch of dumbasses who, who actually believe. They believe this.

• 24:05Neil deGrasse Tyson?

  Okay, there's no excuse. Once we've learned how all this works, there's no excuse to continue to think it's true. And that's what you're talking about. The people who are, are delayed in their acceptance of objective realities. And I'm with you there, but I'm not going to judge people from long ago on today's standards.

• 24:23Chuck Nice?

  Oh, okay. All right, all right, all right. Okay. No, no, you got me. Yeah, that's, that's, I gotta give it to you there. They're, they're perfectly acceptable. They had no other information, so therefore, boom, I get it.

• 24:35Neil deGrasse Tyson?

  Exactly. Exactly. And, you know, right on down to those who imagine that someone have any epileptic seizure, were being invaded by the devil, right? And so you go get the priest and they do the holy water and then they come out of these symptoms. The seizure's over, the 20-minute seizure ends, it just ended because how far away is the church? 500 years ago. It's like two blocks away, right? Just in time for the priest to get there. So I, it's, it's, we're trying to make sense of the world. And I, so I don't, you know, I'm okay with that.

• 25:07Chuck Nice?

  You use that, that, that as an example, because I think it's a great example, because we can actually see the brain now. We can see the activity of the brain and exactly what is happening in the brain that causes this epileptic fit. So there is, we're not seeing the devil. What we're seeing is a neurosynaptic breakdown or malfunction.

• 25:30Neil deGrasse Tyson?

  Right.

• 25:31Chuck Nice?

  And so, you know, but where did the devil go? You know, like, if you want to still believe that.

• 25:38Neil deGrasse Tyson?

  Right, but if, fine, in the face of science, just don't lead any science agencies that allocate research funding. Play a job for you in a society.

• 26:02Neil deGrasse Tyson?

  Chuck.

• 26:03Chuck Nice?

  Yes.

• 26:04Neil deGrasse Tyson?

  I got a fast one for you.

• 26:06Chuck Nice?

  Alrighty.

• 26:07Neil deGrasse Tyson?

  This one is gonna be about wheels.

• 26:09Chuck Nice?

  Okay, I'm gonna say, uh, I'll say a bit pedestrian for you.

• 26:15Neil deGrasse Tyson?

  Okay. So, did you know that if you're driving down the road?

• 26:22Chuck Nice?

  Okay.

• 26:23Neil deGrasse Tyson?

  Pick a speed, sixty miles an hour.

• 26:25Chuck Nice?

  Nah, that ain't me.

• 26:27Neil deGrasse Tyson?

  Oh, okay, whatever, sorry.

• 26:29Chuck Nice?

  You gotta bump that up by about twenty-five miles, and now we talking.

• 26:34Neil deGrasse Tyson?

  At whatever speed you're going.

• 26:36Chuck Nice?

  Okay.

• 26:37Neil deGrasse Tyson?

  There is a part of your car.

• 26:39Chuck Nice?

  Alright.

• 26:40Neil deGrasse Tyson?

  That is going forward at zero miles per hour, at all times.

• 26:45Chuck Nice?

  Alright, this already got interesting, cuz I, I have no idea what you're talking about right now.

• 26:52Neil deGrasse Tyson?

  There's another part of your car that's going forward at twice that speed.

• 26:59Neil deGrasse Tyson?

  At every moment.

• 27:00Chuck Nice?

  Oh, God, okay.

• 27:03Neil deGrasse Tyson?

  What?

• 27:04Chuck Nice?

  Oh, Jesus.

• 27:06Neil deGrasse Tyson?

  Okay. Alright, so, okay, you ready? Okay, are you seated? Okay, here we go.

• 27:12Chuck Nice?

  Here we go.

• 27:13Neil deGrasse Tyson?

  Okay, it's all happening in your wheels. So, the part of the wheel at any moment.

• 27:22Chuck Nice?

  Oh, my God!

• 27:24Neil deGrasse Tyson?

  That's in contact with the pavement is not moving at all.

• 27:30Chuck Nice?

  That's right. Damn!

• 27:34Neil deGrasse Tyson?

  It's, no, if your car were skidding.

• 27:36Chuck Nice?

  Right.

• 27:36Neil deGrasse Tyson?

  Then the part of the wheel in contact with the road would be moving forward.

• 27:40Chuck Nice?

  Would be moving forward.

• 27:41Neil deGrasse Tyson?

  At the rate you're skidding forward.

• 27:42Chuck Nice?

  But that's why you're moving forward!

• 27:44Neil deGrasse Tyson?

  It's why you're moving.

• 27:46Chuck Nice?

  It's why you're moving forward!

• 27:48Neil deGrasse Tyson?

  Because part of the wheel is not moving at all.

• 27:51Chuck Nice?

  Exactly, because if it were, you'd be spinning in place!

• 27:56Neil deGrasse Tyson?

  You'd be spinning in place, correct!

• 27:59Chuck Nice?

  By the way, okay, now, you know what, man? You did it again! You did it!

• 28:08Chuck Nice?

  Cuz I'ma let you know. I, I'm, no, I, I gotta say, I, now, I'm, first of all, this is what I'ma do right now. I'ma publicly apologize to you for all that shit I was thinking.

• 28:22Chuck Nice?

  Cause I was thinking, let me tell you something. I was thinking some stuff. I'm apologize to you right now. Cause you were like, all right Chuck, we're gonna talk about wheels. I'm like, this brother done lost his damn mind. We gonna talk about wheels. Seriously?

• 28:41Chuck Nice?

  But you did it. Go ahead. Let's go for it.

• 28:44Neil deGrasse Tyson?

  Let's keep going. Let's keep going. So the center of the wheel.

• 28:48Chuck Nice?

  Right.

• 28:49Neil deGrasse Tyson?

  Which is, okay, it's spinning, but the exact center is going forward at the same speed the car is.

• 28:57Chuck Nice?

  Absolutely.

• 28:58Neil deGrasse Tyson?

  Okay. The top of the wheel is going forward at twice the speed of the car.

• 29:06Chuck Nice?

  Twice the speed of the car.

• 29:08Neil deGrasse Tyson?

  Okay.

• 29:09Chuck Nice?

  Just like a.

• 29:09Neil deGrasse Tyson?

  At twice the speed.

• 29:10Chuck Nice?

  Right.

• 29:12Neil deGrasse Tyson?

  Okay, because notice if the chassis of the car is moving at the speed of the car, obviously, the top of the wheel is moving faster than the chassis.

• 29:22Chuck Nice?

  Right.

• 29:23Neil deGrasse Tyson?

  Okay. It's moving past the chassis, the top of the wheel well. The wheel well, the top of the wheel well, is going forward at your speed, at your speedometer's speed. The top of the wheel is going faster than that.

• 29:37Chuck Nice?

  Right.

• 29:38Neil deGrasse Tyson?

  To come around to the bottom, so that it's not moving at all.

• 29:42Chuck Nice?

  That's.

• 29:43Neil deGrasse Tyson?

  And if you run the math on that, you get, you get zero at the bottom, the speed of the car in the middle of the wheel, and twice the speed of the car at the top of the wheel. And so this is, this is the geometry, the math and the physics of a, of an axled wheel on any moving vehicle.

• 30:06Chuck Nice?

  What are you doing Chuck?

• 30:10Neil deGrasse Tyson?

  Chuck is smoking something.

• 30:12Chuck Nice?

  I'm just saying. I'm ready to talk about this all day.

• 30:17Neil deGrasse Tyson?

  That could smoke him.

• 30:20Neil deGrasse Tyson?

  But wait, there's more.

• 30:21Chuck Nice?

  That's awesome. That is awesome.

• 30:23Neil deGrasse Tyson?

  But wait.

• 30:23Chuck Nice?

  And because I'm picturing a dot on the wheel and a dot at the chassis. And then it comes, it has to go faster than the top.

• 30:32Neil deGrasse Tyson?

  Faster.

• 30:33Chuck Nice?

  Has to go faster, so it could come around.

• 30:35Neil deGrasse Tyson?

  The top of the wheel, well.

• 30:36Chuck Nice?

  That's right.

• 30:36Neil deGrasse Tyson?

  So it can come around. Correct. So now.

• 30:38Chuck Nice?

  Damn.

• 30:39Neil deGrasse Tyson?

  Now, now think of the wheel that's on a train. Okay? The train wheels are different, right? They're different from car wheels, obviously. So there's the metal flat part that touches the metal rails. But then there's another part that's like an outer, outer, what's the, where should I use that? It's like a coupler. There's an outer part that extends outside of the track.

• 31:07Chuck Nice?

  Right.

• 31:07Neil deGrasse Tyson?

  Okay, can you picture this? It's not just rolling on a track. It's like a lip.

• 31:12Chuck Nice?

  Like a lip on the wheel itself.

• 31:13Neil deGrasse Tyson?

  A lip that extends outside of the track. Which enables the train to stay on the track. Otherwise it'll just drive off, right? So these lips that are exterior to the wheels keep the train aligned on the track. Okay?

• 31:31Chuck Nice?

  Right.

• 31:32Neil deGrasse Tyson?

  But here's what's interesting. They dip below the contact point of the wheel and the rail.

• 31:41Chuck Nice?

  Correct.

• 31:43Neil deGrasse Tyson?

  By a little bit, but whatever it is, they dip below.

• 31:46Chuck Nice?

  Right.

• 31:47Neil deGrasse Tyson?

  All right, well, if the top of your wheel is going twice the speed, the center of the wheel is going the speed, the bottom of the wheel is going zero, anything lower than the bottom of the wheel is moving backwards.

• 32:01Chuck Nice?

  Oh, snap.

• 32:04Chuck Nice?

  That's right.

• 32:04Neil deGrasse Tyson?

  Okay. Okay.

• 32:06Chuck Nice?

  Going in reverse.

• 32:07Neil deGrasse Tyson?

  It's going reverse. So for any train, there are parts of that train that are moving backwards on the track at all times. Wow, that's, that's pretty wild. And, and just picture that, you know, there's the wheel rolling. The part that's below the contact point is moving backwards. It actually lands in a place behind where it started. Right. That means it moved backwards. That's right. That's insane. So I just thought I'd put that out there. I know, it's not, nothing deeper than that. The next time I tie up a woman and put her on the traps, I'm gonna let her know that this, you're gonna learn something.

• 32:52Neil deGrasse Tyson?

  Is this what you do, Chuck? As I twirl my, as I twirl my mustache. Now, here's, here's something interesting. Are you ready? So that means there's a part of your car that's going at all speeds from zero up to twice the speed of the car, correct? That's right. Okay, so imagine this. Imagine attaching some device to your wheel that sends out a microwave signal, and you can adjust it up or down, okay? From the center of the wheel to the outer rim and sends out, or, or from the center of the wheel to the bottom, sends out a microwave signal

• 33:35Neil deGrasse Tyson?

  that will report a speed of your car at any speed you choose. So, the police officer's there with the radar gun, with the return signal that's going 30 miles an hour, even though you're going 60. Yes, so, so they'll get the reflected signal off of your car, right? But if you can override that with a more powerful signal sent from your wheels, you can broadcast any speed you choose down to zero.

• 34:09Neil deGrasse Tyson?

  If it's attached to the wheel.

• 34:11Chuck Nice?

  Right, which is the, that's the speed I'm choosing, by the way.

• 34:18Neil deGrasse Tyson?

  Well, you can't do zero because they know you're lying.

• 34:20Chuck Nice?

  Well, that's, that's.

• 34:21Neil deGrasse Tyson?

  Any place, any place between the center of the wheel and the bottom.

• 34:25Chuck Nice?

  Bottom of the wheel.

• 34:26Neil deGrasse Tyson?

  It will, you can broadcast a speed of that spinning wheel at any speed less than your actual driving speed.

• 34:35Chuck Nice?

  Wow.

• 34:35Neil deGrasse Tyson?

  But it would, to configure this would be really weird and how to make that happen. Cause it has to be moving with the tire. I don't know how you would design the engineering of that. But it's just something to think about because there's always a part of your car that's going everywhere from the speed of your car down to zero and up to twice the speed of the car.

• 34:51Chuck Nice?

  Well, maybe, you know, when the cop pulls you over, you can just tell him, I don't know what speed you recorded. But, uh, it, I don't know, you should have been looking at the bottom of my wheels.

• 35:05Neil deGrasse Tyson?

  Yeah, that'll work in court.

• 35:11Neil deGrasse Tyson?

  So that's all I have to say about wheels.

• 35:13Chuck Nice?

  That's, uh, that was, um, pretty damn good. I mean, sorry, pardon my language. That was pretty doggone good. Uh, that, I, I.

• 35:21Neil deGrasse Tyson?

  Now there's a.

• 35:21Chuck Nice?

  Completely surprised, taken, taken aback by this one.

• 35:25Neil deGrasse Tyson?

  Yeah. And there's another kind of wheel, which is the shape of the object that rotates within a Wankel engine. So if you imagine an equilateral triangle, but curve the corners of it and make the sides a little bit convex, right? So it's a triangle.

• 35:42Chuck Nice?

  I had a Mazda once.

• 35:44Neil deGrasse Tyson?

  Oh, you did? Was it with a Wankel engine? Okay.

• 35:46Chuck Nice?

  Yeah, I had a Mazda.

• 35:47Neil deGrasse Tyson?

  So, so that shape, interestingly, the distance from the bottom to the top remains the same, no matter how it's oriented. So if you roll it along the, uh, uh, if you, I made one of these shapes. In fact, I don't have one with me here. We might have to do another explainer.

• 36:06Chuck Nice?

  We used to call them spirographs when I was a kid.

• 36:10Neil deGrasse Tyson?

  Okay, yeah, so they're related. They're related, right? They're related geometry to it. So if you take a plank and place it on top of one of these triangular shapes and roll it, the plank will be absolutely steady. Even though it looks like the thing is bobbing up and down. It's because there's no central axle to it.

• 36:32Chuck Nice?

  Right.

• 36:33Neil deGrasse Tyson?

  Okay, we think a wheel needs, a wheel that gives you a smooth ride needs one central axle because a wheel is the same distance to each point on the rim. You can design a shape where the top is always the same distance from the bottom, even though the center is moving in your Spirographian sort of way.

• 36:52Chuck Nice?

  Nice.

• 36:53Neil deGrasse Tyson?

  So I actually built one of these when I was a kid in, in woodshop in seventh grade. And I don't think it's with me here.

• 37:00Chuck Nice?

  That is why.

• 37:01Neil deGrasse Tyson?

  It's in a closet somewhere. I'm gonna have to dig it up and we'll do another one. Just fun things to do with, with a wankle engine.

• 37:07Chuck Nice?

  Nice. Yeah, it's an unfortunate name, but yeah.

• 37:12Neil deGrasse Tyson?

  I know, right? It's a little weird. It is a little weird. But it's one of the many engines that have been developed over the years to convert a chemical energy into kinetic energy.

• 37:21Chuck Nice?

  Yeah.

• 37:22Neil deGrasse Tyson?

  So maybe we'll do it, I know, we'll do an explainer just on engines and the history of engines.

• 37:27Chuck Nice?

  Oh, that's a great one.

• 37:28Neil deGrasse Tyson?

  Why they differ from each other and where they're headed. That, that, that's a good one.

• 37:33Chuck Nice?

  That is a good one.

• 37:33Neil deGrasse Tyson?

  And now you know that part of your car ain't moving at all.

• 37:36Chuck Nice?

  But don't use that as the excuse when you get pulled over. That's, that's it.

• 37:42Neil deGrasse Tyson?

  Or don't experiment with how the cop will react if you give that as an excuse.

• 37:45Chuck Nice?

  Right.

• 37:46Neil deGrasse Tyson?

  You don't want to experiment. We gotta call it quits there on StarTalk's Things You Thought You Knew Edition. Chuck, always good to have you. I'm Neil deGrasse Tyson, your personal astrophysicist. As always, I bid you to keep looking up.