Things You Thought You Knew – Oatmeal Sun

Why don’t rockets fly straight up? What’s really happening when you make toast? Neil deGrasse Tyson and comic co-host Chuck Nice break down the science of making toast, boiling water, and the Brachristochrone problem.

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

• 0:00Neil deGrasse Tyson?

  Hey StarTalkians, we put together another Things You Thought You Knew. This one mysteriously combines toast, boiling water, and launching rockets. Check it out.

• 0:13Neil deGrasse Tyson?

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

• 0:27Neil deGrasse Tyson?

  Chuck, I got another explainer for you.

• 0:28Chuck Nice?

  All right.

• 0:29Neil deGrasse Tyson?

  This has to do with making toast.

• 0:32Chuck Nice?

  Okay.

• 0:37Neil deGrasse Tyson?

  I'm just saying.

• 0:38Chuck Nice?

  You know, sometimes when you bring these up, man, I feel like you're just, like you're punking me.

• 0:43Neil deGrasse Tyson?

  No.

• 0:44Chuck Nice?

  I'm like, I'm just like, let me just see if I, what I can get Chuck to go along with.

• 0:49Neil deGrasse Tyson?

  The astrophysics of making toast.

• 0:51Chuck Nice?

  You know, it's like, you know, it's like Neil deGrasse Tyson, right? World-renowned scientist and science communicator. Chuck, I'd love to talk to you about something scientifically relevant. Oh, Neil, please do tell. Let's talk toast. What?

• 1:07Neil deGrasse Tyson?

  All right, so here's the deal.

• 1:09Chuck Nice?

  Okay.

• 1:10Neil deGrasse Tyson?

  All right, and I don't know if you ever paid attention to what's going on inside a toaster.

• 1:13Chuck Nice?

  Okay.

• 1:14Neil deGrasse Tyson?

  All right, but it's fascinating.

• 1:16Chuck Nice?

  I have smoked a lot of weed. I have been high out of my mind. I have never looked at the toaster and went, I wonder what's going on in there.

• 1:28Neil deGrasse Tyson?

  All right, here's the thing.

• 1:30Chuck Nice?

  Okay.

• 1:31Neil deGrasse Tyson?

  Here's the thing. A toast, if you're gonna toast fresh bread.

• 1:35Chuck Nice?

  Okay.

• 1:36Neil deGrasse Tyson?

  Okay, it will spend most of its time in the toaster, most of the time not browning.

• 1:47Chuck Nice?

  Okay, and is this fresh white bread? Because that would make sense.

• 1:54Chuck Nice?

  Yes, it's easier to see the browning on white bread. So this is a white bread example.

• 2:00Neil deGrasse Tyson?

  Okay.

• 2:00Chuck Nice?

  You blame it because let's be honest, in bread society, you know, white bread hasn't the best.

• 2:06Neil deGrasse Tyson?

  They got the best.

• 2:07Chuck Nice?

  Why would I want to give up?

• 2:09Neil deGrasse Tyson?

  But the seven grain blended model is coming along. Okay. So here's the thing.

• 2:14Chuck Nice?

  And let me tell you something, pumpernickel, there goes your property values in the bread box.

• 2:21Neil deGrasse Tyson?

  I forgot all about pumpernickel. That's some dark ass bread right there.

• 2:25Chuck Nice?

  Right now.

• 2:29Neil deGrasse Tyson?

  Okay.

• 2:29Chuck Nice?

  So go ahead. Never mind. I'm about to get us in trouble. I'm gonna stop.

• 2:33Neil deGrasse Tyson?

  All right. So if you if you observe the bread, most of the time, 90% of the time, I didn't know exactly, but it's very high percent of the time it's in the toaster, it doesn't change color at all.

• 2:45Chuck Nice?

  Oh my God.

• 2:47Neil deGrasse Tyson?

  Okay, because it can't change color as long as it's moist.

• 2:56Chuck Nice?

  Okay.

• 2:57Neil deGrasse Tyson?

  Because the highest temperature you can heat the bread is 212 degrees, and that's not hot enough to toast the bread.

• 3:05Chuck Nice?

  I got you. I mean, that really does make sense.

• 3:08Neil deGrasse Tyson?

  You think about this, right?

• 3:09Chuck Nice?

  It's like trying to start a fire with green kindling.

• 3:13Neil deGrasse Tyson?

  You can't. You can't. In fact, if you put a green log on an already established fire, the log is not going to ignite. You know what's gonna happen? It's gonna hiss out all the moisture for the next hour. All right? Because the log can't get hotter than the highest temperature that water can get. And the water that's in the log tops out at 212 degrees. You're gonna have a 212 degree log until there's no water left.

• 3:37Chuck Nice?

  That's cool.

• 3:38Neil deGrasse Tyson?

  And then it'll ignite.

• 3:40Chuck Nice?

  That's right. Oh, wow.

• 3:41Neil deGrasse Tyson?

  Okay, so your toast in the toaster, if you keep looking at it, it's gonna be your white toast. It's gonna be white and white and white. And what the heat is doing, it's like, get out of there, you water molecules. Get out, get out. And it's only doing it to the top edge, not to the middle, because the heat is only hitting the top, the outer edges, right? So.

• 4:00Chuck Nice?

  So the heat is like the black toast matters movement. Yeah.

• 4:08Neil deGrasse Tyson?

  Chuck, you need race counseling, okay?

• 4:13Neil deGrasse Tyson?

  All right. So.

• 4:14Chuck Nice?

  So go ahead.

• 4:14Neil deGrasse Tyson?

  All right. So, once all of the moisture on that outer edge of the bread has evaporated.

• 4:22Chuck Nice?

  Right.

• 4:23Neil deGrasse Tyson?

  It can now toast the bread by, by breaking apart the, the, the, the bread molecules, the proteins and the, and the carbohydrates, revealing the carbon. The carbon is black. Okay. If you leave the bread in too long, it's completely black. All right. But you have all this golden, that all happens in like the last minute that your toaster's in there. Because it took all the rest of that time to heat up the water and evaporate it.

• 4:50Chuck Nice?

  That is pretty doggone cool, to be honest. And I, I got a little excited when you said that because I've never considered it. However, I don't have a toaster. I have a, um, a toaster oven.

• 5:08Neil deGrasse Tyson?

  Okay. So, okay. So in, in the oven, any oven, if you're going to use a broiler.

• 5:13Chuck Nice?

  Right.

• 5:13Neil deGrasse Tyson?

  The same thing.

• 5:14Chuck Nice?

  Same thing.

• 5:15Neil deGrasse Tyson?

  You, you layer the bread and you check, and you're checking it and you keep checking it. You say, it's not making progress. Let me go away for five minutes. No, because the moment the moisture's gone, that sucker browns in instance.

• 5:28Chuck Nice?

  Absolutely.

• 5:29Neil deGrasse Tyson?

  Okay. So it's not a linear, it's not a linear phenomenon. That's all I'm trying to say.

• 5:34Chuck Nice?

  Kind of like if, if it were a graph, it would bump along the bottom.

• 5:37Neil deGrasse Tyson?

  Correct.

• 5:37Chuck Nice?

  And then all of a sudden it shoots straight up almost.

• 5:39Neil deGrasse Tyson?

  Yeah, almost straight up. Correct.

• 5:40Chuck Nice?

  Straight up. So, uh, and I know this because, uh, just the other day when you, it's so weird now. I can't believe that I'm recalling this. I said, what's taking this toast so damn long?

• 5:57Chuck Nice?

  And then I turned, I went into the refrigerator. I pulled out some butter and, uh, um, fig spread.

• 6:06Neil deGrasse Tyson?

  Mm hmm.

• 6:06Chuck Nice?

  And I went back and the toast was brown.

• 6:12Neil deGrasse Tyson?

  There it is.

• 6:12Chuck Nice?

  So that is so wild.

• 6:14Neil deGrasse Tyson?

  You lived this experience.

• 6:16Chuck Nice?

  I lived this experience.

• 6:17Neil deGrasse Tyson?

  It's, it's also why you can, um, boil water in a paper cup.

• 6:24Chuck Nice?

  Okay.

• 6:25Neil deGrasse Tyson?

  Okay, and I've done this experiment many times, so.

• 6:28Chuck Nice?

  So wait, you, yeah, I mean, yeah, you just drop the paper cup inside the pot of boiling water. Okay.

• 6:33Neil deGrasse Tyson?

  No, no, no, that's, that's not what it, no, so you can, you can take a paper cup. And you have to be careful about this because some paper cups have rims on the bottom. That are not actively touching the water on the inside. That will burn, okay? But if you have a wide enough bottom and you have like a Bunsen burner, remember these? And you put the flame on the paper cup in the bottom. If the paper cup has water in it, what is the hottest temperature the paper can get? The temperature of the water. Okay, and so it'll sit there and boil the water. And it'll keep boiling the water until all the water evaporates. Then your paper cup burns.

• 7:11Neil deGrasse Tyson?

  This is why it's so hard to burn someone at the stake. You think, oh, let me just ignite you, this is very medieval here. Let's put you on the stake and just ignite you. You can't just ignite, okay? Yeah, well, there's liquid in you.

• 7:23Chuck Nice?

  Right, the real, the real reason why this is very difficult to do is because we have laws against that now.

• 7:29Neil deGrasse Tyson?

  That's why, okay. That's the actual reason, it's difficult. Thank you, let me get out of my medieval.

• 7:39Neil deGrasse Tyson?

  So what they would do, especially the Catholic Church, to make sure you would burn, that sometimes they would burn you upside down. And that way, um, will control the blood. Or the blood would drain, and as the blood drains, then you have no liquid left in you and you burn faster. Or you can burn in other directions where you retain the blood. Because if you don't want the blood come out, there's some other religious ritual where the, the whole person has to be burned, including their blood. But then the blood has to still evaporate before any, so you'll die before that happens, of course. But in terms of igniting the body, it just doesn't simply happen that way. And this is sped up if you have fast moving air, hot air across the, the food.

• 8:23Chuck Nice?

  Yes.

• 8:23Neil deGrasse Tyson?

  This, this is like a wind heat factor. The op, we have a, we have a, a, an explainer on wind chill factor and wind heat factors.

• 8:31Chuck Nice?

  Yes.

• 8:32Neil deGrasse Tyson?

  Okay, because if it's cold and the wind is blowing, you feel colder.

• 8:35Chuck Nice?

  Colder.

• 8:36Neil deGrasse Tyson?

  If it's hot and the air that's blowing is hotter than your skin temperature, you'll feel hotter.

• 8:42Chuck Nice?

  Right.

• 8:42Neil deGrasse Tyson?

  Okay, so if you put food in, let's say, an air fryer.

• 8:47Chuck Nice?

  Yes.

• 8:47Neil deGrasse Tyson?

  What does that mean, okay? So they are gonna brown your food. Fast because they're moving hot air across and they're evaporating any possible moisture on that surface. And the faster the wind goes, the faster you'll evaporate it, and the faster you can get to the browning.

• 9:05Chuck Nice?

  Can't live without an air fryer. I'm sorry. It's amazing. They're wonderful.

• 9:10Neil deGrasse Tyson?

  Yeah, they they're really air toasters.

• 9:12Chuck Nice?

  Yes.

• 9:13Neil deGrasse Tyson?

  Because, you know, unless the the surface is sprinkled with oil, and then the oil will fry the, you know, you can heat the oil. So you're you're still oil frying, but you're using air to heat the oil to fry the food.

• 9:29Chuck Nice?

  Right.

• 9:30Neil deGrasse Tyson?

  But if it didn't have any oil, it's just a fast toaster.

• 9:33Chuck Nice?

  Exactly. You mean, I spent $400 on a toaster?

• 9:38Neil deGrasse Tyson?

  Yes, you did.

• 9:39Chuck Nice?

  Yes, you did. You did indeed.

• 9:45Neil deGrasse Tyson?

  So that's everything you wanted to know about toast and why it's not a linear process.

• 9:49Chuck Nice?

  Well, that was fun.

• 9:51Neil deGrasse Tyson?

  What don't you do? Oh, do this experiment.

• 9:54Chuck Nice?

  Okay.

• 9:54Neil deGrasse Tyson?

  Take a slice of bread and let leave it out until it just gets hard.

• 9:59Chuck Nice?

  A little crusty.

• 10:01Neil deGrasse Tyson?

  Just leave it out. Okay, we'll get credit. It'll just get get hard. It's no longer squishy. And then you have another one that's squishy that you just took out of the bag.

• 10:09Chuck Nice?

  Okay.

• 10:10Neil deGrasse Tyson?

  They're both at the same temperature.

• 10:13Chuck Nice?

  Right.

• 10:13Neil deGrasse Tyson?

  Okay, now put them both in the in your in your toaster oven. We're both in the toaster, and the one that had the the lost moisture will toast 10 times faster.

• 10:24Chuck Nice?

  Okay.

• 10:25Neil deGrasse Tyson?

  Oh, yeah.

• 10:26Chuck Nice?

  Oh, there you go. So, yeah, and it's already on its way to being toast.

• 10:31Neil deGrasse Tyson?

  That's right.

• 10:33Chuck Nice?

  You leave it out. Well, why you keep leaving the bread out?

• 10:37Neil deGrasse Tyson?

  Toasting the bread. Pre-toasting. Pre-toasting.

• 10:41Chuck Nice?

  It's a pre-toast.

• 10:42Neil deGrasse Tyson?

  And one other thing, a reminder of how surface deep the color is.

• 10:48Chuck Nice?

  Okay.

• 10:48Neil deGrasse Tyson?

  Because it's only what that sort of radiative energy can touch. And anything's behind anything else is not seeing your toaster thing. All right. So a reminder of that is if you happen to burn the toast.

• 10:59Chuck Nice?

  Right.

• 11:00Neil deGrasse Tyson?

  You just take a bread knife or a knife, not, you know, a knife and scrape off the black.

• 11:05Chuck Nice?

  Right.

• 11:06Neil deGrasse Tyson?

  And then there's like, and you can, you can salvage many a burnt toast that way.

• 11:11Chuck Nice?

  Or you could just accept the fact that it is black and enjoy it for its beautiful blackness.

• 11:18Neil deGrasse Tyson?

  You could do that as well. Okay.

• 11:25Neil deGrasse Tyson?

  Yeah, Chuck totally, definitely needs race therapy. I know.

• 11:32Neil deGrasse Tyson?

  So, so maybe there's more than you ever cared to know about making toast. No. But I put that, the thermodynamics of toasting. That is awesome. We gotta title this just that, the thermodynamics of toasting. Okay, of toast. Yeah, and so, and, and, and the takeaway here is however long you're staring at the unbrowned toast, let that not be the measure of how much longer you have to wait. Yes.

• 12:12Speaker 02

  I'm Brian Futterman and I support StarTalk on Patreon. This is StarTalk with Neil deGrasse Tyson.

• 12:28Neil deGrasse Tyson?

  So Chuck, I'm gonna tell you how to boil water. Uh, so for this explainer, I am going to go and get a sandwich. You fill a pot with water. Now you put it on the stove, then you turn on the heat, be it electric, coil, or gas. This is groundbreaking stuff.

• 12:47Neil deGrasse Tyson?

  So you're heating the pan. Right. And then the bottom of the pot is heating the bottom of the water. That makes sense, so far. So you'd expect the water at the bottom of the pot to be hotter than the water at the top of the pot. Yeah. So, as it gets hot, the water molecules vibrate faster and faster. Right. If your molecule's sitting next to me, and you're not vibrating as fast as I am. I'm like, calm down, man, calm down. What is your problem? Geez. But you will ultimately succumb, and my vibrations will send you into vibrating. Ah. You will send the adjacent molecules next to you. It's called conduction. It's how, if you have a fireplace poker, or the handle of an iron pan on the stove, the pan gets hot,

• 13:32Neil deGrasse Tyson?

  eventually the handle gets caught. Lord, have I learned that the hard way. Okay, so the iron molecules start vibrating, and they, they tickle the molecules next to it, set them vibrating, and that is heat. Energy going out of the pan, up the handle to your hand to burn you unless you get a pot holder. Right. So the liquid will conduct heat.

• 13:56Neil deGrasse Tyson?

  Until that's not fast enough. Conducting is slow. You can hold the handle of an iron pan for at least five minutes. Long time. Meanwhile, you're frying an egg, right? Yeah, exactly. So there's a point where the heat is vibrating the molecules faster than the molecules can communicate that fact to molecules above it. Aha. So the solution to this is blobs of water rise up from the bottom.

• 14:29Neil deGrasse Tyson?

  You don't see the early bits of this, okay? Because the water is completely transparent and there aren't any bubbles yet. Right. But the hot water rises. Right. Physically moves. That can't happen in your iron pan because it's solid. The iron can only move heat through conduction. Right. But the moment the heat becomes significant, whole pockets of water will rise up, replaced with cool pockets of water that were above that come in below. If I rise up, something's got to take its place. Right. If you want to test this next time, put in a few raisins at the bottom. Sounds like an awful dish.

• 15:11Neil deGrasse Tyson?

  So you'll see the raisin bob up and down inside the liquid. Ooh. And it's doing that because it's following. Following the pockets of water. There you go. So convection is a way to get heat from one place to the other by physically moving blobs of the stuff. And so convection can't happen in solids, but it can happen in liquids and in. Air. Air, gas, okay. But it's not boiling yet. What happens when it boils? I'll tell you when it's boiling. It's boiling when at the bottom of the stove. It is so hot, the water at the base of the pot turns into steam. Wait, inside? Inside. Wow.

• 15:52Neil deGrasse Tyson?

  So you have a ball of steam there, and so plus it's gas. Gas underwater is gonna rise fast. Exactly. Now, the early bubbles of steam, these are cool. The early bubbles, you'll see them start, and as they move their way up, they get smaller and smaller and they disappear. Right. Because the, the water above that layer is not at boiling temperature yet. It's cool. It's cooler. So it's cooling down this steam bubble, turning it back into water. Interesting. So when the bubble is formed and keeps the same size the entire route to the top, then you have 212 degrees boiling water.

• 16:36Neil deGrasse Tyson?

  So boiling water is really just, it's just water farting, basically. That's exactly what I was thinking.

• 16:47Neil deGrasse Tyson?

  If you fart in a swimming pool, that bubble will not disappear. That'll just stay a bubble all the way up. That's the easiest way to get kicked out of a pool party. Why are there bubbles coming from your suit? Coming from your rear end. No, none of what I just said is why I have this explainer with you. Okay, plot twist. Have you ever

• 17:10Neil deGrasse Tyson?

  had a pure pot of water

• 17:14Neil deGrasse Tyson?

  boil over? Oh, no, it never boils over. But wait.

• 17:20Neil deGrasse Tyson?

  When you make spaghetti, it can boil over? Yes, it can. What is the most boil over substance known to man in a morning stove? The most, oh, oatmeal. Oatmeal. Oatmeal. Oatmeal. Oatmeal. So why does water not boil over?

• 17:38Neil deGrasse Tyson?

  But oatmeal does. Why? I will tell you. I'm ready. There they are, slowly coming up to temperature. The pure water gets to 212. A blob of steam rises up and escapes the top. Right. What happens to that same blob of steam in the oatmeal? It can't get out! Right. There's oatmeal in the way! But it has to get out. Right. Thermodynamically, it has to escape. So, you have these bubbles, and they say, "We're getting out no matter what." "We're bustin' loose out of this pot." And the only way to do that is to expand the layers of oatmeal, so that it has pockets

• 18:23Neil deGrasse Tyson?

  of water that it can come out through. If you start out with a pot of oatmeal that's one-third full, that puppy will expand to the complete height of the pan, so that the steam can get out. Hmm. The sun, when it dies, you always heard it say, "It becomes a red giant." Right. When the sun dies, it runs out of hydrogen in its core. It converted all the hydrogen to helium. Alright, there's a certain luminosity associated with that. Fine. Now I just have helium. What's next? The sun collapses, then it starts fusing helium into carbon. That happens at a higher luminosity.

• 19:03Neil deGrasse Tyson?

  The sun gets brighter. More energy is coming in from the core of the sun. But wait. That energy can't get out of the previous sun. It has the same problem with the oatmeal. Okay? The previous sun had a transparency of energy to it that gave it its current size. Right. When you boost the energy level of the core, it can't get out until it busts out. And it is gonna get out. And en route, it takes the sun and swells it Oh. into the size of a red giant star. Now the energy can get out. And it goes from its current size to hundreds of times bigger. Oh my goodness. You thought your oatmeal spilled over.

• 19:48Neil deGrasse Tyson?

  The sun is basically spilling over out of its pot. Wow. Which is why, if you want to tame the oatmeal, you have to lower the heat. Lower the heat? As much as you can. We can't do that to the sun. The sun is stuck with the high energy. It's gonna puff up and become a huge red giant star.

• 20:04Chuck Nice?

  Hmm.

• 20:05Neil deGrasse Tyson?

  So, under high heat, the oatmeal wants to become a big giant star, basically. Trying to get the energy out.

• 20:12Chuck Nice?

  Right, right.

• 20:13Neil deGrasse Tyson?

  Lower the heat, which the sun doesn't have the power to do. Now it can bubble and you can cook the oatmeal.

• 20:19Chuck Nice?

  So the sun has no choice but to go ahead to keep expanding.

• 20:22Neil deGrasse Tyson?

  Correct.

• 20:23Chuck Nice?

  Until it becomes its own delicious breakfast explosion.

• 20:28Neil deGrasse Tyson?

  Whereas you, the chef in the morning, have the option to lower the heat on the oatmeal.

• 20:32Chuck Nice?

  Right.

• 20:33Neil deGrasse Tyson?

  So the oatmeal boils over for the same reason the sun gets big. The energy can't get out and it has to thin things up above it so that the energy can find its way out. And it does.

• 20:44Chuck Nice?

  That's super cool.

• 21:09Neil deGrasse Tyson?

  Jack.

• 21:09Chuck Nice?

  Yes.

• 21:10Neil deGrasse Tyson?

  I got some obscure stuff to share with you.

• 21:12Chuck Nice?

  My favorite obscure.

• 21:14Neil deGrasse Tyson?

  I don't know if it'll be worth it, but let me test it out on you. What distinguishes a rocket from an airplane, among many things, is that a rocket has to work as it ascends the atmosphere where there's less and less oxygen.

• 21:27Chuck Nice?

  Okay.

• 21:28Neil deGrasse Tyson?

  So it can't depend on oxygen in the air for the combustion in the rocket. Whereas an airplane, it doesn't have to carry its oxygen because the oxygen is sitting there minding its own business in the atmosphere.

• 21:41Chuck Nice?

  And then the airplane sucks it in and...

• 21:43Neil deGrasse Tyson?

  Sucks it in and mix it with the fuel and ignites it and there you have it. So the way they say that in rocket lingo is the rocket carries its own oxidizer.

• 21:51Chuck Nice?

  Oh, okay.

• 21:52Neil deGrasse Tyson?

  The space shuttle, which doesn't launch anymore, had two different kinds of fuel. You've heard of the solid rocket boosters on the side. We still use those today. You know how they burn? They burn from the middle outward.

• 22:05Chuck Nice?

  Well.

• 22:05Neil deGrasse Tyson?

  As though you're unraveling a toilet paper roll from the center.

• 22:09Chuck Nice?

  Interesting.

• 22:10Neil deGrasse Tyson?

  So if you have a toilet paper roll, remove the cardboard and then you just start pulling on it.

• 22:14Chuck Nice?

  Right.

• 22:15Neil deGrasse Tyson?

  It slowly unravels from the center. So in a solid rocket booster, it's a cylindrical core. Of fuel and as it burns, it only has one exit hole and that's the bottom.

• 22:29Chuck Nice?

  Right.

• 22:30Neil deGrasse Tyson?

  And that exit hole gets wider and wider and wider as it continues to burn. It ablates that inner surface until it runs out completely and then you're done. And then you drop them off and you keep going.

• 22:43Chuck Nice?

  Interesting.

• 22:44Neil deGrasse Tyson?

  Yeah. So that's how the solid rocket boosters work. By the way, once they're ignited, you can't shut them off.

• 22:49Chuck Nice?

  I hope you're igniting them at the right time.

• 22:53Neil deGrasse Tyson?

  And they're clamped down until they ignite. And then when they ignite, they break away because you can't, there's no stopping them. Once they're lit, the shuttle's off. Okay. It's like, there it is. You can't do anything until they're done. Whereas the main engine, you can throttle that. You can go high or low. The main engine was that big orange segment and that has two tanks in it. Hydrogen and oxygen. The hydrogen tank is twice as big as the oxygen tank.

• 23:22Chuck Nice?

  I think I'm hearing a little H2.

• 23:24Neil deGrasse Tyson?

  Oh, H2O. Oh. How do you concentrate the most amount of this hydrogen gas and oxygen gas? You liquefy it.

• 23:34Chuck Nice?

  Right.

• 23:35Neil deGrasse Tyson?

  So you chill it so that it liquefies. And then you have a rather extensive set of valves and nozzles that recombine the hydrogen and the oxygen. And that is highly exothermic, which means it releases energy. And, and what is the waste product?

• 23:51Chuck Nice?

  Well, it's got to be water.

• 23:52Neil deGrasse Tyson?

  Water. There it is.

• 23:53Chuck Nice?

  So that begs the question, why isn't all of our fuel done this way? I mean, the planet is dying. We actually have this technology?

• 24:01Neil deGrasse Tyson?

  Some car, they call hydrogen fuel cells.

• 24:03Chuck Nice?

  Okay, that's right.

• 24:04Neil deGrasse Tyson?

  Now, hydrogen is very flammable. So I don't know if they've worked out the engineering mechanics of how to make that practical.

• 24:11Chuck Nice?

  How to put that together without blowing everybody up.

• 24:13Neil deGrasse Tyson?

  Right, exactly.

• 24:15Chuck Nice?

  A little like, oh, the humanity every other day.

• 24:20Neil deGrasse Tyson?

  Stop. Did you know that when Orson Welles did the radio play of H.G. Wells's War of the Worlds?

• 24:28Chuck Nice?

  Right.

• 24:29Neil deGrasse Tyson?

  He studied the vocal intonations of that announcer?

• 24:34Chuck Nice?

  You're kidding me.

• 24:35Neil deGrasse Tyson?

  And copied them for the announcer who saw the aliens.

• 24:39Chuck Nice?

  Making everything sound that much more dramatic and tragic.

• 24:43Neil deGrasse Tyson?

  And tragic and real and scary. Do you ever notice when it launches, a few seconds later, it executes the what?

• 24:51Chuck Nice?

  The roll.

• 24:52Neil deGrasse Tyson?

  The roll program. What I'm about to describe is for everything that goes in orbit. Half the energy of that rocket is not there to get it up into space.

• 25:05Chuck Nice?

  Half?

• 25:06Neil deGrasse Tyson?

  Half the energy is to take it downrange.

• 25:10Chuck Nice?

  Ah.

• 25:11Neil deGrasse Tyson?

  That's why every rocket you have ever seen launched doesn't just keep going up.

• 25:16Chuck Nice?

  Right.

• 25:16Neil deGrasse Tyson?

  Ever stop and wonder?

• 25:17Chuck Nice?

  When I was younger and I would watch these launches, because they were such a big thing and you had to watch them even in school, I used to think, well, they're never going to make it to space. They're going sideways.

• 25:29Neil deGrasse Tyson?

  Thank you. That's an observant point to make. So it goes from zero miles per hour to 18,000 miles per hour sideways.

• 25:44Chuck Nice?

  Nice.

• 25:44Neil deGrasse Tyson?

  Because once the rockets stop.

• 25:47Chuck Nice?

  Right.

• 25:48Neil deGrasse Tyson?

  Does it fall out of the sky now?

• 25:50Chuck Nice?

  No.

• 25:51Neil deGrasse Tyson?

  Wait, it achieves orbit. So what is orbit? There's that one magic speed where you are going so fast downrange that you are falling to earth at the same rate that earth is curving away from you. And Isaac Newton first demonstrated that, and that is the definition of an orbit. You don't need rockets. You will stay in that configuration. So my only point is, so many people look at rocket launchers and think they're going up into space.

• 26:21Chuck Nice?

  Right.

• 26:21Neil deGrasse Tyson?

  When.

• 26:23Neil deGrasse Tyson?

  What we call space in the zero G environment when people go is orbit.

• 26:29Chuck Nice?

  Right.

• 26:30Neil deGrasse Tyson?

  You go into orbit around Earth and they're not very high above Earth's surface, couple hundred miles. That's it. That's the distance from New York to Boston.

• 26:39Chuck Nice?

  Yeah.

• 26:39Neil deGrasse Tyson?

  Or New York to Washington DC. You could drive that distance in four hours.

• 26:43Chuck Nice?

  Yep.

• 26:43Neil deGrasse Tyson?

  Obedying speed limits. It's just something that people might not have noticed. Now, if you're not going into orbit, then all of your energy is going to just go up and then you just drop back to Earth. The Bezos Branson billionaire boys race.

• 27:01Chuck Nice?

  Okay, so Branson's billionaires boys race. That's.

• 27:04Neil deGrasse Tyson?

  Boys race. Okay.

• 27:05Chuck Nice?

  Love it.

• 27:05Neil deGrasse Tyson?

  All right. Elon went into orbit.

• 27:08Chuck Nice?

  Right.

• 27:08Neil deGrasse Tyson?

  My man Elon knows what orbit is.

• 27:11Chuck Nice?

  He knew that he had to get out of here. He knew.

• 27:15Neil deGrasse Tyson?

  He needs an escape hatch.

• 27:16Chuck Nice?

  He was like, I.

• 27:17Neil deGrasse Tyson?

  Coming after me. He comes after me.

• 27:19Chuck Nice?

  I'm planning for the future. I'm gonna find a way to get out of here. I'm planning for the future.

• 27:24Neil deGrasse Tyson?

  When the pitchforks are coming.

• 27:27Chuck Nice?

  Bezos and Branson, they can come back. They got a place to come back to. I know. I got to go.

• 27:37Neil deGrasse Tyson?

  So he, so they, Bezos and Branson, what they're doing is they're going up and then shutting off their engines. And just falling back to Earth.

• 27:49Chuck Nice?

  Right.

• 27:50Neil deGrasse Tyson?

  They land in the same place they took off from. Alright, so they didn't, they didn't go down range at all. They did not go into orbit. So they go up and then they fall. And while you are falling, where there's no air molecules, which is that famous Carmen line that they reach, you drop you from there, you are weightless. I'll tell you one last thing, which is completely obscure, is for physics geeks out there.

• 28:14Chuck Nice?

  Okay.

• 28:15Neil deGrasse Tyson?

  There's something called the brachistocron problem.

• 28:17Chuck Nice?

  Okay, now you certainly are going deep now. This is a deep cut on the B side.

• 28:22Neil deGrasse Tyson?

  Let's have a, a round ball.

• 28:25Chuck Nice?

  Right.

• 28:26Neil deGrasse Tyson?

  At some height and it wants to get to the bottom of a hill. The question is. What shape should that hill take? So that the ball gets to the bottom of the hill fastest? If you make the hill just a straight line from where it is to the bottom. Okay, it'll roll down and it'll get there.

• 28:44Chuck Nice?

  Yes.

• 28:45Neil deGrasse Tyson?

  But if you make the hill drop first and then curve out the bottom, you can get some serious speed here and that stuff, that puppy will roll out fast. Okay, this is called the brachistichrome problem.

• 28:59Chuck Nice?

  Nice.

• 28:59Neil deGrasse Tyson?

  And it requires sort of Hamiltonian representations of the energy of the system to solve it. Okay, the Bernoulli brothers posed these to each others. They were two math brainiacs. Anyhow, the solution to this problem is first a drop, a pretty steep drop before it curls out to the bottom. And that will beat the straight line every time.

• 29:23Chuck Nice?

  Of course.

• 29:24Neil deGrasse Tyson?

  That curve, if you flip it up,

• 29:30Neil deGrasse Tyson?

  that is the trajectory to launch a rocket.

• 29:32Chuck Nice?

  Oh, oh, oh, watch out. Yo, that is a physics mic drop right there. Yeah.

• 29:44Neil deGrasse Tyson?

  So that's how to get into orbit the most efficiently.

• 29:47Chuck Nice?

  It's very elegant, by the way.

• 29:49Neil deGrasse Tyson?

  Yeah, and it's just an interesting question. When you're curious and you're mathematically literate and you know a little bit of physics, these questions come up in your life and you're compelled to solve them as the Bernoulli brothers did.

• 30:01Chuck Nice?

  Nice. Oh, those Bernoulli brothers, you know, they were something at a cocktail party, that's for sure.

• 30:14Neil deGrasse Tyson?

  The life of the party.

• 30:17Neil deGrasse Tyson?

  So unfortunately, they never knew that this was also a rocket solution for them, but.

• 30:23Chuck Nice?

  That is really super cool.

• 30:26Neil deGrasse Tyson?

  All right, that's been another StarTalk explainer with my co-host, friend and buddy, Chuck Nice.

• 30:32Chuck Nice?

  Always a pleasure.

• 30:33Neil deGrasse Tyson?

  Neil deGrasse Tyson here, as always. Keep looking up.