Space Elevators, Skyhooks, and Space Fountains

What is the fastest, cheapest and possibly worst way to get into space? Could a nuclear explosion launch a manhole cover beyond the Earth’s atmosphere? And could space elevators, skyhooks or launch loops one day replace rockets? In this episode, Professor Hannah Fry and Michael Stevens (VSauce) explore where space really begins, why orbit means falling forever, and how Newton’s cannon explains the motion of the International Space Station. They also interrogate the physics of the Kármán line, orbital velocity and geostationary orbit, before asking whether humans could ever climb a staircase to space, or catch a rotating skyhook into orbit. Plus, the far future fate of Earth, firing a bullet around the Moon, the true value of the Apollo Moon landing, the ethics of colonising Mars and whether the future of space exploration should belong to private companies or the public! ------------------- For more information about Cancer Research UK, their research, breakthroughs and how you can support them, visit ⁠https://www.cancerresearchuk.org/our-research/rest-is-science Cancer Research UK is a registered charity in England and Wales (1089464), Scotland (SC041666), the Isle of Man (1103) and Jersey (247). A company limited by guarantee. Registered company in England and Wales (4325234) and the Isle of Man (5713F). Registered address: 2 Redman Place, London, E20 1JQ. ------------------- Find The Rest Is Science all over the internet by ⁠⁠clicking here.⁠⁠ ------------------- Video Producer: Adam Thornton + Oli Oakley + Jack Meek Animator: Sam Benson Video & Social: Bex Tyrrell Assistant Producer: Lucy Lipscombe Producer: Simona Rata Senior Producer: Lauren Armstrong-Carter Chief Digital Officer: Samuel Oakley Exec Producer: Neil Fearn Learn more about your ad choices. Visit podcastchoices.com/adchoices

• 0:00Speaker 00

  Hello, welcome to The Rest Is Science. I'm Hannah Frank.

• 0:02Speaker 01

  And I am Michael Stevens. Today, we're going to talk about going to space. The fastest way, the cheapest way, the worst way.

• 0:11Speaker 00

  All of the above, or?

• 0:14Speaker 01

  All of the above.

• 0:15Speaker 00

  Is all of the above contained within one single answer?

• 0:18Speaker 01

  What if there's one answer? Actually, yes, I believe, I did not think of it this way, but you're right. There's one answer to all three of those questions. The cheapest, fastest, and worst way to go to space would have been to have been a borehole cover.

• 0:36Speaker 00

  Right, I was gonna say.

• 0:37Speaker 01

  In 1957 during Operation Plum Bob.

• 0:39Speaker 00

  Sitting on top of a nuclear bomb.

• 0:41Speaker 01

  So here's the story. It's a very famous one because it's kind of funny. It's also kind of historically important, but there is controversy over whether or not this particular steel borehole cap, which is often called a manhole cover, survived. So in 1957, the United States was doing a whole bunch of nuclear testing. This was called Operation Plum Bob. It was happening in Nevada in the summer. And they did some underground nuclear explosions. And for the second one, Pascal B, they said, hey, let's seal a plate over the borehole, underneath which, underground, we're going to do a nuclear explosion. Let's see if this lid can contain it.

• 1:22Speaker 01

  So this lid was a 2,000 kilogram, like 900 pound steel lid.

• 1:27Speaker 00

  Massive.

• 1:27Speaker 01

  And they stuck it on there and then they blew up the atomic weapon. And this manhole cover blew straight up. They had a camera.

• 1:37Speaker 00

  Well, they had cameras. Right, yeah, okay. Because they were reverse engineering how fast it was going based on the frame rate.

• 1:43Speaker 01

  That's all they could do. And this camera was taking frames like every millisecond. The manhole cover appears in just one frame. So they estimated that it was traveling at about six times Earth's escape velocity, which is to say about 150,000 miles per hour, also known as 67 kilometers per second.

• 2:08Speaker 00

  That is fast.

• 2:10Speaker 01

  If that's how fast it was going, then it's the fastest human launch ever from Earth's surface, still to this day.

• 2:19Speaker 00

  Fastest way to get into space, yeah.

• 2:20Speaker 01

  Fastest way to get into space. Worst way, because almost certainly this manhole cover did not survive. It would have just been ablated in the atmosphere and completely burned up. Poor guy.

• 2:31Speaker 00

  Also, the idea that you're like, okay, we're going to get you to space, don't worry. Just, just sit yourself down here on top of this nuclear bomb. I can't think of anything worse. I can't think of anything worse.

• 2:43Speaker 01

  And that's why I think it could also be the cheapest, because the manhole cover didn't have to pay. Now, obviously, Operation Plum Bob cost a lot of money, but if you just had run in there, sat down on it, boom.

• 2:59Speaker 01

  This episode is brought to you by Cancer Research UK.

• 3:02Speaker 00

  Scientists have found that cancer risks usually increase with age and size, but some species defy the odds.

• 3:08Speaker 01

  For example, deep sea Greenland sharks. They can grow over six meters long, weigh more than a small car, and yet live for up to 400 years.

• 3:19Speaker 00

  Now, understanding how Greenland sharks' cellular repair and immune systems seem to have managed to keep them cancer-free for centuries, that could open up exciting research pathways.

• 3:30Speaker 01

  Essentially, over millions of years, evolution has been running the world's most successful cancer prevention trial. And sometimes breakthroughs can be found in unusual places.

• 3:41Speaker 00

  So by exploring the unexpected, Cancer Research UK scientists are uncovering new ways to tackle over 200 types of cancer. Their work has helped to double survival in the UK over the last 50 years and continues to save and improve lives around the world.

• 3:57Speaker 01

  For more information about Cancer Research UK, their research and breakthroughs and how you can support them, visit cancerresearchuk.org/the rest is science.

• 4:09Speaker 02

  Observe the North American dad. 50s, great polo collection. He enters his vehicle information on Carvana. An offer appears in minutes. Remarkable. He squints, reads it again, smiles and says, dang, that's a good offer. The highest form of approval. No haggling, no hassle, no one called him boss. He's still on the couch. Astonishing. Sell your car today on carvana.com. Pickup fees may apply.

• 4:40Speaker 03

  This episode is brought to you by Google Chrome. You think you know a browser, but Gemini and Chrome, that's new. It can help you with practically anything on the web, like restoring a vintage motorcycle from a 50-page restoration block, or finally break down that long article you've had open for weeks. Gemini and Chrome is here for it. Ready to make anything online make sense? There's no place like Chrome. Check responses. Setup required. Compatibility and availability varies. 18 plus.

• 5:11Speaker 01

  Within a blink of an eye, you're in space. And human-made objects have gone faster since then. I think New Horizons and the Parker Solar Probe both have gone faster, but not during launch.

• 5:25Speaker 00

  It feels like you've answered the setup to this episode extremely quickly now. You said, we're going to talk about the worst, the cheapest, and the fastest. And then we've got one answer. We're done, no?

• 5:34Speaker 01

  And there's the answer.

• 5:35Speaker 00

  Yeah.

• 5:36Speaker 01

  So as always, send in your questions to the rest is science at goldhanger.com. And we'll see you next week. No, I think, I think what we should do now is talk about the slowest way to get into space.

• 5:48Speaker 00

  Okay.

• 5:48Speaker 01

  Okay. And then, and then between those two extremes, we'll find something that might be better.

• 5:54Speaker 00

  All right, deal.

• 5:55Speaker 01

  The slowest way to get to space, in my opinion, is what I call the just wait method. Your body's ultimate destiny is to be in interstellar space. It's just going to take a really long time.

• 6:12Speaker 00

  Are we talking about the death of the planet here?

• 6:14Speaker 01

  We are talking about the death and the wandering of our planet. It really depends on what we described by being in space, because I kept, I kept coming back to this point as I was researching this episode. Like, if you want to be in space, congrats, you're already there. Earth is in space. You are in the Milky Way Galaxy right now. And you're on a little spaceship called Earth, but I don't know, it doesn't feel very satisfying to be like, oh, I'm already in space. I'm in our solar system. Usually, when we talk about going to space, we mean outer space. We mean leaving Earth, leaving its surface, leaving its atmosphere. I think we can all agree on that.

• 6:52Speaker 00

  Beyond where Katy Perry went. I think Katy Perry's sort of like the lower limit of what I would accept.

• 6:57Speaker 01

  How high did Katy Perry go?

• 7:00Speaker 00

  105 kilometers, 65 miles.

• 7:03Speaker 01

  So, so let's actually start there, okay? Let's call 105 kilometers the Katy Perry line.

• 7:10Speaker 00

  The KP line.

• 7:12Speaker 01

  The KP line. If you can get above the KP line, then you've done it. For, for the purposes of this episode, that's where we want to go.

• 7:20Speaker 00

  Just to put that into perspective, the International Space Station is 400 kilometers, 250 miles.

• 7:25Speaker 01

  Yeah. I'll tell you, doing the math for this episode, I have so many different units. Kilometers, miles, feet per second, kilograms, grains. It's going to be a real ride.

• 7:39Speaker 00

  The Karman line, which is sort of widely recognized as the line, the boundary that separates Earth's atmosphere from space, is at 100 kilometers. So technically, technically Katy Perry did go into space.

• 7:54Speaker 01

  She did. She definitely did. I 100% agree with that. Here's the deal. Let's talk about the far future of the Earth. Someday, you will die. But your body will most likely still be here on Earth. So let's consider that, you know, your legacy, what's, what's left of you, it's your matter. And that'll be on Earth, but then what's going to happen to it in the long run? Well, in like seven, eight billion years, the Sun might engulf the Earth. The Sun is going to start running out of the fuel it's burning. It's going to swell into this red giant. It's going to almost certainly swallow up Mercury and Venus.

• 8:36Speaker 01

  Whether or not it actually swallows up Earth is very hotly debated. Some people say yes. Some people, especially recently, say actually maybe not.

• 8:44Speaker 00

  Hmm, we're too far out.

• 8:45Speaker 01

  Now, I want to, I want to say, as we've been mentioning, these ejections from the solar system and from the galaxy are just probabilities. If they don't happen, then within 10 to the 20, which is 100 quintillion years, Earth's orbit will have faded away due to gravitational radiation, and it truly will fall into what's left of the Sun. So at least, within...

• 9:10Speaker 00

  Okay, we've got a bound here. We've got an upper lower bound.

• 9:13Speaker 01

  100 quintillion years, you will get to be inside the Sun.

• 9:17Speaker 00

  Wait, how old is the universe again?

• 9:20Speaker 01

  Oh, well, the universe is only like 15 billion years old.

• 9:23Speaker 00

  That's a baby. So you've got nine zero. This is like billions of times older than the age of the universe currently.

• 9:30Speaker 01

  Oh, billions of times. Yeah.

• 9:32Speaker 00

  13.8 billion.

• 9:33Speaker 01

  You'd have to wait longer than the universe has even existed by, by a lot before any of this happens. But I'm saying there's a chance, okay?

• 9:45Speaker 00

  Sure, yep.

• 9:46Speaker 01

  If the Earth is swallowed up by the Sun, then congratulations, you will visit the Sun in like seven or eight billion years. Just wait, it's a great way to travel through space. However, if Earth is not engulfed by the Sun, then it's got a lot longer before it gets to go on a special journey. In about 10 quadrillion years, if, if the Sun does not suck up the Earth, in 10 quadrillion years, the Earth will likely be ejected from the solar system by some stellar remnant or something that's happened, something that's passed by our solar system. And to be fair, that doesn't really count as traveling through space because you'd still be on Earth. It's just that Earth would now be this lost planet.

• 10:30Speaker 00

  Wait, how did you get 10 quadrillion years there? Is that just like the probability?

• 10:35Speaker 01

  That's just the probability, yeah. In, in 10 quadrillion years, the Sun will just be this like dwarf star that will, will still be capable of having things orbit it. It's not going to be producing the like warmth that anyone would like at all. However, Earth could still be just like there as this like cold, solid.

• 10:56Speaker 00

  Dead planet.

• 10:57Speaker 01

  And your, your grave could still be there, you know? Could still be like in memory of Michael Stevens and there's no one to read it. But, you know, it's still like.

• 11:06Speaker 00

  It could be there, it could be there.

• 11:07Speaker 01

  Within 10 quadrillion years, we could get ripped out by some passing thing. And now we're going across the galaxy. And Earth could go around the galaxy, taking us on this great trip for like 10 quintillion years before probability says we will most likely have been ejected from the galaxy itself or fallen into a supermassive black hole.

• 11:32Speaker 00

  Okay, because this is what happens to, to kind of great big floating ice rocks. I mean, there are lumps of matter that are on that trajectory around the, the solar system around the galaxy already.

• 11:45Speaker 01

  Now astronomers and cosmologists have, you know, predicted these probabilities. We don't really know exactly when and how all this will happen, but we do know something about its likelihood. To recap, what I'm saying is if you wait, if you wait a quadrillion, I may have been saying 10 quadrillion. It's, well, I mean, what's a factor of 10?

• 12:04Speaker 00

  Hey, among friends, in a quadrillion.

• 12:06Speaker 01

  These numbers are so estimated that going off by one magnitude of 10 in one direction or the other is like not really a huge crime.

• 12:16Speaker 00

  Well, also, I mean, you're talking about probability here, right? So you work out the chances of something like that happening, some intergalactic object knocking us off course and sending us off spinning into the galaxy. And it's an extremely small probability. And then you essentially work out how much time it would be for that probability to essentially be satisfied. But it could happen on day one, could happen like, you know, in a couple of years' time. We don't know.

• 12:41Speaker 01

  It could happen during this podcast.

• 12:43Speaker 00

  Right. We can't be sure, we can't be sure.

• 12:46Speaker 01

  But within, within a quadrillion years, I'd put money on that bet.

• 12:51Speaker 00

  Yeah, right, there you go.

• 12:52Speaker 01

  So you have that to look forward to. Within a quadrillion years, your body will get to ride around on Earth through interstellar space. Even more exciting is that during this interstellar journey through the Milky Way, when Earth is just this lost rogue planet, within about 10 quintillion years, it's likely that we will either be ejected from the galaxy altogether or absorbed into a supermassive black hole. That is exciting.

• 13:22Speaker 00

  Here's what I think is cute about that, is that you're still using the unit of years despite this period of time. The, uh, the, the period when we were orbiting the Sun was like a single eye blink at the birth of our, of your existence, you know?

• 13:41Speaker 01

  Yes.

• 13:41Speaker 00

  But still measuring things in years would be sort of a cute archaic remnant of, of a long lost past.

• 13:48Speaker 01

  I think cute is the right word because of course for these quintillions of years where Earth is a rogue planet with no star, there's no, there's no year, there's no sidereal year. We're not orbiting around a star. But I'm just imagining that there's like some really poor group of people who are like, oh, man, what are we? Like they, they took some immortality potion and now they're just stuck on this planet with no sun. And they're like, oh, should we keep using years? I mean, there aren't seasons anymore, but it would be cute. You know, it'd be a little throwback.

• 14:20Speaker 00

  They could still be alive though. If they, if they harnessed, you know, the power of nuclear fusion and were living underground, they could feasibly, they could feasibly still be alive.

• 14:30Speaker 01

  They, yeah, totally, totally. That's a great premise for a sci-fi novel. Now, whether that counts as visiting outer space, maybe not because you're still on a planet. But here's, here's the final stage. It could be, we're not sure yet, but it could be that eventually protons decay, including the protons that make up your body. They could, after a long, it's gonna have to be a long period of time because we've never like seen this happen. We can't be like, oh, the half-life of a proton is, you know, 12 years. Like everything's always evaporating. Now, it's not a totally agreed whether this will happen or not. There's a lower bound on like how long it takes

• 15:12Speaker 01

  for, for like a proton to have a chance of like 50% chance of decaying away into radiation, and it's huge.

• 15:20Speaker 00

  When you say huge, how huge are we talking?

• 15:22Speaker 01

  This is how huge I'm talking.

• 15:23Speaker 00

  Okay.

• 15:24Speaker 01

  According to the internet.

• 15:27Speaker 00

  I've heard of it.

• 15:28Speaker 01

  Within 100 undecillion years, all of your protons will have evaporated away as radiation.

• 15:38Speaker 00

  I don't even know what an undecillion is.

• 15:41Speaker 01

  Ah, good question. An undecillion is a one followed by 36 zeros.

• 15:47Speaker 00

  Okay.

• 15:48Speaker 01

  So 100 undecillion is a one followed by 38 zeros.

• 15:53Speaker 00

  Right.

• 15:53Speaker 01

  And that is a really exciting time that I'm looking forward to because at that point, I or what, or my remnants are traveling on their own through intergalactic space as radiation.

• 16:07Speaker 00

  Well, because at that point, I mean, you will be muons, neutrinos, you'll be all of the subatomic particles. But hang on a second, if protons do disintegrate into, into subatomic particles, we know that you can get subatomic particles from them because I mean, that's what the whole idea of CERN is, right? Is that you take two protons and you smash them together and then you get this sort of this array, this kind of like scattergun of, of subatomic particles. But you're saying if they decay sort of without a high energy collision, well then, doesn't that mean that everything is going to disintegrate?

• 16:43Speaker 01

  Yes. If protons decay, then the ultimate fate of the universe, long after the heat death, long after energy is the same everywhere, uh, meaning like temperature is the same everywhere and no work can be done. The universe will be cold for literally decillions of years before we start to notice, oh, things are leaving, like solid matter is radiating away. And then the universe will just be empty until another big bang happens.

• 17:16Speaker 00

  You know, you could, um, at this point, you could absolutely make up a, um, a big number, a word for a big number, and I would just fully believe you. Ucilian, decilian, you, you know, you can make up your own one by now.

• 17:28Speaker 01

  The names of big numbers are awesome. Like there is a formula to it. And I made a short, um, where I counted through all these, uh, names for, you know, for numbers.

• 17:39Speaker 00

  Every factor of a thousand, yeah.

• 17:40Speaker 01

  Thousand, million, billion, trillion, quadrillion, quintillion, sextillion, septillion, octillion, nonillion, decillion.

• 17:50Speaker 00

  I'm okay with that, but where's usilian?

• 17:52Speaker 01

  Undecillion.

• 17:53Speaker 00

  Undecillion, sorry, usilian is what you say to someone if they're being a bit of a woolly.

• 17:59Speaker 01

  You're basically saying the word 11. So it's, it goes right after decillion, undecillion, and then treticillion.

• 18:06Speaker 00

  Okay.

• 18:07Speaker 01

  I don't remember them all, but you can look this up. Like names of larger numbers of E-SOS might give you the short. It's very fun because I go all the way up to a Google. So there we go, there we go. Somewhere between the blink of an eye and 100 undecillion years.

• 18:24Speaker 00

  Feel like you're giving us quite a wide range.

• 18:25Speaker 01

  There's gotta be a better way to get to space. So obviously, the solution we're using right now is rockets. Rockets are expensive, they're noisy, they need to have a huge amount of, of just propellant as their mass, like eighty, ninety percent of their mass is just the fuel they need to get up into low earth orbit. So that's also what makes them so expensive. You know, we've got reusable rockets now that have made this, you know, a little bit better. So using the Falcon Heavy, Falcon Nine, it costs about two to three thousand dollars per kilogram to get something into space.

• 19:06Speaker 00

  Wow.

• 19:07Speaker 01

  Which means it costs millions to, to, to, to launch, you know, these rockets. But have we considered a stairway to space?

• 19:17Speaker 00

  Go on.

• 19:18Speaker 01

  Cause you don't need to explosively go up. You can just slowly climb your way up. And to build a stairway to space, you gotta first agree on where space is.

• 19:31Speaker 00

  I'm going for the KP line.

• 19:32Speaker 01

  Down to the KP line, but I'm gonna go back because I wanna take back something I said, which is we're not gonna use the KP line, we're gonna use the Karman line, because that's the one that I used for all my figures. I don't wanna have to add five kilometers.

• 19:44Speaker 00

  They're pretty much, they're pretty much the same. They're pretty much the same.

• 19:47Speaker 01

  So where is outer space? And the Karman line is one of the most famous agreed upon, like definitions of that's where space begins. What is the Karman line? It was proposed by Theodore von Karman, who said, I think the best way to say where space begins is to say where airplanes stop. Where aeronautics is replaced by astronautics. The difference being that below the Karman line, there's enough air, the atmosphere is thick enough, that a vehicle can travel with lift alone. It propels itself forward, smashes into enough air that it's lifted up and it flies like an airplane.

• 20:27Speaker 01

  Above the Karman line, there's just so little atmosphere that lift is not possible and you've gotta just be a rocket. So I think that's a great, that's a great definition and that line is, he calculated it to be about eighty kilometers above the surface of the earth, but today it's set at a hundred kilometers, sixty two miles.

• 20:47Speaker 00

  So when you say, hold on a second, when you say you gotta just be a rocket instead, we're talking here that you have to be traveling fast enough that you're falling in the earth's orbit, but the earth is moving enough that it sort of catches you as you fall. I mean, that's essentially what we're talking about, right?

• 21:03Speaker 01

  Not yet, because I'm not talking about orbits. I'm just talking about getting to space.

• 21:06Speaker 00

  Wait, what do you mean? When he says above this point, you can't be an airplane anymore, you have to be a rocket. What do you mean?

• 21:12Speaker 01

  I mean, you cannot go up anymore because of

• 21:15Speaker 00

  Lift alone.

• 21:16Speaker 01

  Aerodynamic lift. The only way to keep going up is to throw propellant out

• 21:21Speaker 00

  Right, got you.

• 21:22Speaker 01

  And fly like a rocket.

• 21:25Speaker 00

  Got you.

• 21:25Speaker 01

  You cannot have thrust that moves you forward and then, and then your wings hit the air and you go, oh, cool, I'm lifting up. You've gotta just shoot the propellant down,

• 21:35Speaker 00

  Got you.

• 21:36Speaker 01

  Thrust yourself up like a rocket. That line is traditionally set at a hundred kilometers. To build a staircase that you could walk to get to the Karman line would probably be pretty difficult. I don't know how much it would cost.

• 21:51Speaker 00

  Details, details.

• 21:53Speaker 01

  Those are just details. I do have one detail for you. If we assume that a, that a step is the standard, like eighteen centimeters high, it would take five hundred and fifty five thousand, five hundred and fifty six steps to get to space.

• 22:10Speaker 00

  Okay. And if you're doing ten thousand steps a day, we're talking two years.

• 22:15Speaker 01

  Well, yes, but that's like the ten thousand steps a day tend to be just like steps forward. Steps up are pretty darn difficult. Like ignoring the effects of the thinning atmosphere, it would take a long time. So I looked up how quickly people can climb stairs. And to climb up to space, it's gonna take like, it's gonna take more than three months for a, for a healthy person who's really, really intent on doing this.

• 22:43Speaker 00

  Are they stopping to sleep?

• 22:44Speaker 01

  No, no stopping to sleep.

• 22:45Speaker 00

  Okay.

• 22:46Speaker 01

  This is just constant climbing. To put this in perspective, the tallest building on earth, the Burj Khalifa, it's, it's not a hundred kilometers tall, it's point eight kilometers tall. And it has fewer than three thousand steps, two thousand nine hundred and nine steps. We need more than half a million steps to get to space.

• 23:05Speaker 00

  You also, in the UK, every sixteen steps, you need to have a little landing that is at least as long as the stairs are wide. So

• 23:15Speaker 01

  Yes.

• 23:16Speaker 00

  Maybe it's just in the UK, but building regs say it.

• 23:19Speaker 01

  This staircase that I'm imagining, it totally follows all regulations.

• 23:23Speaker 00

  Sure.

• 23:23Speaker 01

  It's got safe places for people to rest. I don't know if, how a human would do on this staircase. The best stair climber, our species as it was created, is Christian Roberto Lopez Rodriguez.

• 23:39Speaker 00

  Okay.

• 23:39Speaker 01

  This is a guy from Spain who has two world records for stair climbing.

• 23:43Speaker 00

  Okay.

• 23:44Speaker 01

  He climbed vertically on stairs, like on a stair machine, not on real stairs, because we don't have tall enough ones. He climbed eighteen point seven kilometers vertically in twenty four hours, over seventy thousand steps.

• 23:57Speaker 00

  Okay, so he's, he's, he's a fifth of the way there.

• 24:00Speaker 01

  He did it in

• 24:02Speaker 00

  In a day.

• 24:03Speaker 01

  Twenty four hours.

• 24:05Speaker 00

  Right.

• 24:05Speaker 01

  And by the way, he wasn't, he wasn't climbing eighteen centimeter stairs, he was climbing like thirty some odd centimeter steps, like twice as steep as normal ones. So Christian, you're our only hope. He also has the record for endurance for just climbing stairs for an entire week. And listen to this, listen to this. He, he climbed for a week and he managed to climb stairs for a vertical gain of one hundred point four seven five kilometers.

• 24:36Speaker 00

  Uh, hello, hello.

• 24:39Speaker 01

  Hello, Karman line, he passed it.

• 24:41Speaker 00

  He did.

• 24:41Speaker 01

  It took him a week to walk to space.

• 24:44Speaker 00

  I wanna see, what's his name? I wanna see his thighs. What's his, what's his name?

• 24:48Speaker 01

  Christian Roberto Lopez Rodriguez.

• 24:52Speaker 00

  Let's have a look. He looks normal. Let me just make sure I'm looking at the right person, because he also has the Guinness World Record for the fastest hundred meter sprint in stilettos.

• 25:03Speaker 01

  Wow, let's get this guy on the podcast.

• 25:05Speaker 00

  Christian Roberto Lopez Rodriguez, wow.

• 25:09Speaker 01

  From Spain.

• 25:10Speaker 00

  From Spain. He's only three point two four seconds slower than Jamaican runner and eight time Olympic gold medal winner, Usain Bolt's hundred meter sprint world record. Suppose it's the same thing, really, sort of like you're going up, aren't you? Your toes are up, sort of same skill. Maybe we should do that, maybe we, we should ask him when he is the first person to, to go to climb to space. He should do it in stilettos.

• 25:32Speaker 01

  Oh, yeah, I'm, I'm sure he will. We just need someone to build the stairway to space first.

• 25:37Speaker 00

  Simple.

• 25:37Speaker 01

  And then Christian Roberto Lopez Rodriguez.

• 25:41Speaker 00

  Off you go.

• 25:42Speaker 01

  You'll be the first. That sounds like a huge undertaking, climbing all of these steps, but keep in mind, we're talking about a hundred kilometers, like it would take an hour to drive to space if it was a flat horizontal thing.

• 25:55Speaker 00

  What about a stener stairlift? One of the things that the elderly people get installed in their houses.

• 26:00Speaker 01

  Right, why a stairway to space when it could be an escalator to space?

• 26:04Speaker 00

  Do you know what I mean?

• 26:05Speaker 01

  And so that's a perfect segue into what we should talk about next, which is, well, first of all, how we actually get to space. We use rockets. We use rockets because they, you could just build one thing, you don't have to build half a million stairs, which like couldn't even stand up on their own. Like the, the, the scale of something that's of a building that's a hundred times plus taller than the Burj Khalifa, we wouldn't even know how to do that. But we know how to build a rocket that just uses propellant to blast itself up into outer space. However, rockets are really expensive and they're really loud and they're really dirty and they're pretty risky.

• 26:49Speaker 01

  So there's gotta be something better. Right now, if you wanna send a kilogram of mass to outer space, using something like Falcon Heavy, Falcon Nine, that's gonna cost you two to three thousand dollars, you know, per kilogram. But there are ways that could be easier. If we, if we, for example, just built a escalator to space, then you could just put your kilogram of material on the escalator and wait.

• 27:13Speaker 00

  Off you go.

• 27:14Speaker 01

  It could cost like, like literally a dozen dollars to get something into space.

• 27:19Speaker 00

  I mean, you can pack out that escalator, have it as a conveyor belt, you know? People coming up, people coming down, it's easy.

• 27:25Speaker 01

  The problem though, is that generally, we don't just want stuff or people to be in outer space, we want them to stay there and like orbit. And an orbit is very different than just being up really high. At the height of the International Space Station, gravity is still ninety percent of what it is down here on the surface. So if I climbed a staircase all the way up, four hundred kilometers to where the International Space Station is, and then I stepped off, I'd fall back down to earth. Like I wouldn't, in order to orbit, I have to do something very, very different. And so I, I know you're familiar with this, but I'm gonna talk about Newton's cannon.

• 28:09Speaker 00

  Yeah.

• 28:10Speaker 01

  Which is, I think, a really great way to picture what exactly is going on when we talk about falling objects, orbiting objects and escaping objects. I wonder if you guys out there have seen the demonstrations of the fact that if you, if you fire a gun horizontally forward on earth, and at the same time, from the same height as the barrel of the gun, drop a bullet. So one, you drop one bullet, the other one gets fired out of the gun, which one hits the ground first?

• 28:41Speaker 00

  Exactly the same time.

• 28:42Speaker 01

  Yes, both of them hit at exactly the same time because the vertical acceleration caused by gravity is completely separate from the horizontal velocity given to the bullet by the gun. You might think, yeah, but what about like the, the, isn't there some kind of lift that the air would give the moving bullet? And like not much, because we've actually done this in real life and the bullets hit the ground at the same time. They don't hit in the same place, the one that you just drop, it falls down at your feet, the one you shoot, it's, you know, far, far away, but it's still only stayed up for the same amount of time.

• 29:16Speaker 00

  Next time we do some recordings in the States, Michael, I'm petitioning that we do this experiment live, we go to a shooting range. I wanna do this live.

• 29:25Speaker 01

  Well, we should do that. And you know what? We should go down to Alabama and hang out with Destin from Smarter Every Day, cause he'll have the equipment.

• 29:33Speaker 00

  Yeah.

• 29:33Speaker 01

  He'll have the locations.

• 29:35Speaker 00

  Guns, yes, yes.

• 29:36Speaker 01

  By equipment, I mean guns. Yeah, yeah.

• 29:52Speaker 01

  This episode is brought to you by Cancer Research UK.

• 29:54Speaker 00

  Dentist appointments, MOTs, routine checkups help us to spot faults early before we need a root canal or breakdown at the side of the road. And cancer screening is the same idea.

• 30:05Speaker 01

  It's about aiming to spot cancer early before symptoms show and when treatment works best. The UK's breast, bowel, and cervical cancer screening programs developed with Cancer Research UK save thousands of lives every year.

• 30:19Speaker 00

  Today, Cancer Research UK is backing innovations that could transform the future of screening. Picture a smart bra that could one day detect breast changes as it's worn, making screening more accessible.

• 30:31Speaker 01

  And AI trained on a database of over 10 million mammograms that helps doctors spot early signs of cancer.

• 30:38Speaker 00

  Research like this saves and improves lives.

• 30:41Speaker 01

  For more information about Cancer Research UK, their research and breakthroughs and how you can support them, visit cancerresearchuk.org/restisscience.

• 30:54Speaker 03

  This episode is brought to you by Google Chrome. You think you know a browser, but Gemini and Chrome, that's new. It can help you with practically anything on the web, like restoring a vintage motorcycle from a 50-page restoration blog, or finally break down that long article you've had open for weeks. Gemini and Chrome is here for it. Ready to make anything online make sense? There's no place like Chrome. Check responses set up required compatibility and availability varies 18 plus.

• 31:19Speaker 04

  Your heart can tell you a lot about your health. Apple Watch Series 12 measures your heart rate every five seconds with the most accurate heart rate sensing in wearable. So your vitals app, now with heart rate variability, can tell you when something is off. And your readiness score can let you know when to rest and when to push. Hear the story in every heartbeat with Apple Watch Series 12. The features described are for wellness purposes only and not for medical use. iPhone 11 or later required. Based on Apple conducted study of heart rate accuracy, August 2026. Visit apple.com slash Apple Watch Series 12.

• 31:54Speaker 01

  Okay, so anyway, that's an important piece of physics to keep in mind, that, that these, these two different directions, down and, and forward are, are independent. Just because you're moving horizontally doesn't mean you're falling any quicker or more slowly. But what if I made this gun fire the bullet faster? Well, then it will go a further distance, but it will still, you know, drop at the same rate. It'll still hit the ground in the same amount of time. If I keep increasing the speed of that bullet, eventually something really interesting comes into play, which is the fact that the earth is curved. Eventually, that bullet can be moving so quickly that it drops, just like a bullet that I just

• 32:38Speaker 01

  drop out of my hand, but yet it's traveled so far horizontally that the earth itself has also dropped underneath it. It's curved. Now, wait a second. If I get it just right, that means that I can get my fast-moving bullet to fall just as quickly as the earth's curvature falls away from it. So it never hits the earth. It just keeps falling forever. And that is what we call an orbit.

• 33:04Speaker 00

  That is what the International Space Station is doing essentially at all times.

• 33:08Speaker 01

  Exactly, exactly. So, so the reason the astronauts in the International Space Station are floating around isn't that there's no gravity. There's a bunch of gravity. There's 90% of the gravity we're feeling right now up there. It's just that they are falling. They are falling, but Earth's surface falls away from them just as quickly, so they never hit it. Now, eventually, they do need to give themselves little boosts because there's a bit of air up there. There's enough that over the course of like a month, their orbit decays a bit and they come closer, they have to kind of boost back up. Instead of saying that there's no gravity, I like to just say that there's no G-force in the International Space Station. When you're in an orbit, when you're in free fall, there's definitely a lot of gravity. That's why you're falling. But there's no G-force. There's no weight.

• 33:52Speaker 01

  There's no feeling of weight and being pressed down against something.

• 33:56Speaker 00

  It's essentially the same trick as those vomit comets, you know, the, the parabolic flight things, where they kind of go up and then drop, and then go up and then drop. And when you're in free fall, you have the experience of zero G on your body.

• 34:08Speaker 01

  Yeah, exactly. As long as you're falling, you'll feel just like you're in the International Space Station. Problem is, most of the ways we can easily fall don't last very long.

• 34:19Speaker 00

  Oh, yeah. Not, not without some sort of conclusion at the end.

• 34:22Speaker 01

  Okay, so the reason I'm bringing up orbits is that when it comes to thinking of ways to get to space that aren't just rockets, it's important that we not only come up with ideas that get us high enough, get us up above 100 kilometers, but also ideas that allow us to stay up there, orbit the earth, or even escape earth and go off to other places, the moon, Mars. Okay, so, so, so before we get into other non-rocket launch ideas, I want to talk about what, what kind of speeds are required for an orbit. The closer you are to the surface of the earth, the faster you have to go because gravity is stronger.

• 35:05Speaker 00

  Like imagine, imagine that this is exactly the same principle of Newton's cannon, but you're firing the gun and you're firing it so fast that it essentially orbits the entire earth before it falls.

• 35:17Speaker 01

  Yes. So how do you, how do you do, can I do that?

• 35:21Speaker 00

  Yeah, go on.

• 35:21Speaker 01

  On the surface of the earth? Well, as it turns out, no, but hypothetically, yes. So if you are six feet tall and you throw a baseball, it will eventually hit the earth, unless you throw the baseball at 7,910 meters per second. That is the orbital velocity required for a circular orbit around earth at six feet altitude. So.

• 35:48Speaker 00

  Probably something's going to get in the way also, like a tree or a mountain or another person's head.

• 35:53Speaker 01

  Probably a tree, a mountain, a person. But I'll tell you what will get in the way: air. At that speed, at 7,910 meters per second, your baseball will last for the blink of an eye. It is going to explode into a fireball. But if we ignore the air, okay, then a baseball thrown at almost 8,000 meters per second, it's going to literally orbit the earth at human height. And so you could throw it forward and then wait a few hours and then get hit in the back of the head. Or you could catch it. You could play catch with yourself without having to just like throw the ball up.

• 36:31Speaker 00

  You can need quite a big mitt. It's going very fast.

• 36:35Speaker 01

  It's going very fast because we're ignoring air resistance. So it's, it's literally still going 8,000 meters per second when it hits you. And also, if we're ignoring air resistance, how far will the ball have dropped by the time it gets back to you? Zero. It won't have dropped at all. It's in an orbit. But there's some good news here. If you go up higher, gravity is less strong. So you don't have to go nearly as fast to stay in orbit. If you went up to the top of the Burj Khalifa, listen to this, your baseball doesn't have to travel at 7,910 meters per second to orbit. It only needs to travel at 7,909 meters per second. Hey, they're coming down, Michael. They're coming down.

• 37:17Speaker 01

  It, I mean, literally, the speed the baseball needs to go is the speed that the ISS orbits at.

• 37:22Speaker 00

  Hang on, I've got it here. It's 7,670 meters per second.

• 37:26Speaker 01

  Whoa, 7,600, so 300 miles per hour less. I feel like I could throw a baseball that fast.

• 37:32Speaker 00

  Dropping. So it'd be easier, wouldn't it? More achievable. Let's be clear though, right? The International Space Station is not blasting rockets out one side, pushing it 7,670 meters per second, right? When they sort of put it up there, you can, you can basically put it into an orbital path where effectively has the, that's the relative motion that it has in comparison to the earth. So you're not like continually blasting rocket fuel to keep you going at that insane speed.

• 38:04Speaker 01

  No, no, you don't need to constantly blast fuel to keep yourself going fast up there because there's, there's just not enough resistance from air. You're just kind of moving and your inertia has nothing to resist it. So you just keep going. And like I said, there is something to resist you. There is like a very, you know, sparse atmosphere there. So you do lose velocity over time. You are decelerated and you do eventually need to give yourself some boosts. I think we've talked about this on the podcast before. I've definitely talked about it in a, in a short video before, but if like everyone on earth just suddenly died from some huge catastrophe and the astronauts in the ISS

• 38:46Speaker 01

  were still alive, the first thing they would run out of would not be food or water or even air. The first thing they would run out of would be altitude.

• 38:57Speaker 00

  Right. Yes, we did. That they would slowly crash down to earth.

• 39:01Speaker 01

  It all depends on how much fuel they have at that moment. But they need regular deliveries of fuel for these periodic boosts, usually like one or two a month. But they have more than that supply of air, water and food. So yeah, their concern would be, ah, we're coming back down. Before they're like, oh, I'm hungry.

• 39:23Speaker 00

  Yeah.

• 39:23Speaker 01

  This theoretical orbiting baseball idea on Earth is kind of disappointing. The baseball would get torn apart by friction with the air. Like even if we devised a method to get it moving that quickly. But what we can do to do something fun like this for real is go to the moon. Because the moon has so much less gravity that standing on the moon, orbital speed at six feet is only sixteen hundred meters per second.

• 39:53Speaker 00

  Whoa, okay. You could surely build a automatic ball pitcher that was able to do that, surely.

• 40:02Speaker 01

  You surely could. I mean, and we already have. When I first looked this up years ago, there was like one gun that definitely could do it. And it was called the Paris gun. But since then, there have been some exciting developments in bullet speed, in projectile speed.

• 40:19Speaker 00

  If this is going back to Destin and Alabama and smarter every day's gun cupboard, I'm here for it.

• 40:26Speaker 01

  Well, yeah, maybe it should. Orbital speed, six feet above the surface of the moon, is, just to reiterate, sixteen hundred meters per second, more or less. And again, what that means is that you could throw a baseball or kick a football. Let's, you know, be UK about this. If you kicked it at that speed, straight forward at six feet up, it would go all the way around. Two hours, approximately two hours later, it hit you in the back of the head. And if it didn't hit you in the head, it would just fly by you and it would keep going around the moon for almost forever. Because the moon just doesn't have an atmosphere that's going to slow anything down. But I looked this up. I looked up like, what is the fastest bullet?

• 41:11Speaker 01

  And I found this YouTube channel called Banana Ballistics. It was fascinating. This guy was like, how fast can I get a bullet to go? And he, you can go to his channel and it's literally, the video is called like fastest bullet. You can go to his video to look up what cartridge and barrel length he was using. But he used a bullet that was made of brass and only weighed twelve point five grains. What, how heavy is that? A grain is a seven thousandth of a pound.

• 41:39Speaker 00

  Whoa, okay.

• 41:41Speaker 01

  Which means this brass bullet weighed about as much as like four or five postage stamps. That's it. And he was able to fire it at Mach four point seven.

• 41:51Speaker 00

  Which is?

• 41:52Speaker 01

  Which is higher than Mach four point six, which is orbital speed, six feet above the moon.

• 42:00Speaker 00

  Oh, that's cool.

• 42:01Speaker 01

  Fire this bullet on the moon and then you got two hours to duck because that bullet's coming right back from the other side.

• 42:10Speaker 00

  It's probably not gonna do that. Well, I don't know. It's going pretty fast. But I was just thinking about like, if it weighs a few postage stamps, how much damage would it actually be able to do? But, you know.

• 42:18Speaker 01

  It does a lot of damage.

• 42:20Speaker 00

  At sixteen hundred meters per second.

• 42:22Speaker 01

  That's the thing that's so amazing because it's going so fast that the physics are very different. And he demonstrates in his video, the difference between like a heavy bullet that's going at a normal speed and a tiny bullet going really fast. And the tiny one going really fast actually does more damage to like hard armored steel plates than the regular one. So that could, yeah, that's for a future episode with Destin.

• 42:49Speaker 00

  Deal.

• 42:50Speaker 01

  That's a fun little investigation of orbital speeds. But the most exciting orbital speed, especially for our purposes today, is the speed you have to travel at to orbit the Earth when you are thirty five thousand, seven hundred and eighty six kilometers above the Earth.

• 43:06Speaker 00

  Wait, why that number?

• 43:07Speaker 01

  That number is really special because the speed you have to travel at horizontally to not fall down to the surface of the Earth is exactly the same speed as the speed of Earth's rotation.

• 43:19Speaker 00

  Oh.

• 43:20Speaker 01

  So you are geosynchronous. You are orbiting the Earth and yet you're not really moving around it. You are staying right above the same point on Earth's surface.

• 43:32Speaker 00

  You've got a geostationary orbit essentially.

• 43:34Speaker 01

  That's what it is. That is geostationary orbital.

• 43:37Speaker 00

  Wait, how far did you say? Three thousand?

• 43:40Speaker 01

  Thirty five thousand kilometers.

• 43:42Speaker 00

  That's insane.

• 43:43Speaker 01

  But yeah, I mean, International Space Station, four hundred kilometers. Geostationary orbit, thirty five thousand.

• 43:50Speaker 00

  I'm so astonished. Good fact.

• 43:55Speaker 01

  Or here's one of the things that's cool about a geostationary orbit. We put something up into a geostationary orbit. It's way up there, thirty five thousand kilometers up. It's not moving to the side or anything. It's just staying right above us. So if we dropped a really long ladder all the way down from that geostationary satellite, it would just like hang here. It wouldn't have to touch the ground and we could just start climbing up this ladder. Except, not really. Because that ladder and our weight on it is going to pull it down.

• 44:29Speaker 00

  Of course, because there's more gravity. Absolutely.

• 44:32Speaker 01

  Yeah. And so to counteract that, here's a quick idea. Let's just put another cable, another ladder or tether coming out the other end of our geostationary satellite. It's got a counterweight on it.

• 44:46Speaker 00

  Right. It's like an elevator.

• 44:47Speaker 01

  This is what we've talked about so many times on the podcast, the space elevator.

• 44:52Speaker 00

  Oh, my gosh.

• 44:53Speaker 01

  It's literally a space elevator. Now, the counterweight is further away than geostationary. So it's actually having to go faster. And the physics behind it is that it's trying to get flung out. If you cut the cable, connecting it to the rest of the elevator, it would fly off into a higher orbit. But when the whole thing is together, it just stays there. And so it's literally like a ladder or an elevator or a tether or whatever, whatever we make this structure be, a thing that goes all the way down to Earth. And then it doesn't even touch the ground. It can be, you know, it can be ten feet above the ground. It could be ten inches above the ground. And it would just stay there and we could climb up it.

• 45:38Speaker 01

  Really, not climb, but we could build little pods that mechanically climbed up it and could take all kinds of payloads, all kinds of supplies, people, crews, all the way up to the geostationary little base. And this would cost, I mean, it's hard to know what this would cost, but it would be so cheap.

• 46:01Speaker 00

  Once you had it up and running. Once you had it up and running.

• 46:04Speaker 01

  That's the problem. It's going to be obviously a giant structure that you have to build. It's going to be really expensive. And we currently don't know of any materials strong enough.

• 46:19Speaker 00

  Yeah, I was gonna say the tensile strength of the steel cable that you're dangling down from thirty five thousand kilometers away. It's gonna, I mean, that's gonna, it's gonna take some engineering.

• 46:30Speaker 01

  The tensile forces of Earth pulling this down and then the counterweight trying to be flung into a higher orbit, that's so strong. There is a material that can do it and it's carbon nanotubes, but we currently don't know how to make them long enough.

• 46:45Speaker 00

  Right.

• 46:45Speaker 01

  So the space elevator concept, while really cool, while like literally if we figured it out, it would be a game changer. There would be human history before space elevators and human history after. It would be a turning point because suddenly going to space would be so much easier, a thousand times easier. We would basically have a road to space, okay? Which we don't currently have. Every other thing humans do, driving, sailing, flying, there's infrastructure. There are airports, there's roads, there's rails for trains. But we don't have anything, any piece of infrastructure that takes us to space. We just have the vehicle and it's got to just go.

• 47:22Speaker 00

  What have we been doing? What have we been doing?

• 47:24Speaker 01

  I think that we will, and I'm not a hundred percent convinced it's going to be a space elevator that we figure out. Because there are other things we could do already that would do the same thing, basically. Would still be incredibly cheap. Like instead of three thousand dollars a kilogram for a launch, it'd be like three hundred, you know, maximum. So another idea is called a skyhook. And the skyhook idea is sort of like a much smaller space elevator. It's just like a long tether that's in orbit. And it can be in just low Earth orbit, but it's rotating. So you got to imagine like a cartwheeling rope. If you're watching, I'm spinning my pencil around its middle.

• 48:10Speaker 01

  And this is how, and it's orbiting Earth while it spins. So it's like a circle rolling around the outside of another circle. If you imagine that, then you can see how one point of it, the point that touches the ground is always sort of stationary for a moment. And then it zips back up. The idea here is that you would literally have a hook that kept swinging down into Earth's lower atmosphere and then flying back up and then coming back down. And it could come back down into like, I don't know, an airplane height. It doesn't have to come all the way down to where it's gonna like hook onto a person.

• 48:45Speaker 00

  If you time it just right.

• 48:48Speaker 01

  If you timed it just right, you could jump onto this hook, which while it's just above Earth's surface pointing straight down, it's literally stationary for a moment. So you could just hop on and then you're gonna get whipped back up into space. We wouldn't have it come all the way down to the surface. You know, it could just be at like an airplane height. We could fly payloads up there, clip it onto the hook and then boom, they get like launched up into orbit. Obviously, you lose some energy when you do that. So the skyhook's gonna keep needing to be kind of like boosted back up. But that's not necessarily that hard. If the skyhook is low enough, you can generate electricity from Earth's magnetic field because you're moving through Earth's magnetic field as a skyhook. And what do we know about moving through a magnetic field?

• 49:32Speaker 00

  Yeah.

• 49:33Speaker 01

  Electric current. So we could power this thing and it doesn't need to have a huge boost. Like we've got to have some big, you know, liquid fuel explosion. It can just slowly accelerate itself back to where it needs to be using Earth's magnetic field as an energy source and do all this work for us and launch things up. But my favorite, my favorite idea is a launch loop. A launch loop is a structure that we literally could make today. It would be very expensive, but we could make it.

• 50:08Speaker 00

  We've got the science for it. Go on.

• 50:10Speaker 01

  It would, it would work. Like, we don't even really need to do any demonstrations. We already know that this physics works. Building a, like, just a building that's really tall, eh, you know, that, that might not be very easy. Because the building has to support itself statically. But what if we built something that actively supported itself? What if we built something that was just a mega wild inflatable silly tube man? The way those things stay up is not because they're so strong.

• 50:41Speaker 00

  Yeah, they're not strong at all.

• 50:42Speaker 01

  They're being supported actively by air being blown into them. And those air molecules fly up and they eventually hit the sides and the top of the, the, the baggy structure. And their momentum gets transferred and the thing stays up. Now, it wobbles around a bunch, so we would want to maybe not use air and, uh, wobbly, uh, materials.

• 51:04Speaker 00

  Oh, I thought you were gonna say that in the arms, the arms are sort of being flung around a little bit. You could sort of, you could

• 51:09Speaker 01

  Oh, yeah.

• 51:10Speaker 00

  Jump onto one of them and get flung up.

• 51:12Speaker 01

  I'd be afraid, though. Yeah.

• 51:15Speaker 00

  It's uncontrollable.

• 51:16Speaker 01

  Maybe, could you build an inflatable tube man with wobbly arms that are whipping around? And they're whipping at a high enough altitude that they're not breaking themselves apart. That's the other concern.

• 51:28Speaker 00

  Yeah.

• 51:28Speaker 01

  And then you just have to grab onto its arm when it's low and then it'll whip you up.

• 51:31Speaker 00

  I like this idea of like a wind tunnel, though. Like, it's sort of like a tube, you're pumping air in, which you're absolutely right, you could do. I mean, you could even have, like, sections along it that were, where you added in extra air. You, I mean, you know, when you go, um, indoor skydiving, when people do that? Where you're sort of going into a wind tunnel and then it just blows you upward? This is, I mean, that's basically what you're describing, right?

• 51:55Speaker 01

  Yeah, yeah, except instead of using air, uh, we could use something even more massive. The concept of a launch loop is that you have a, a long tube and you evacuate the air from it. And how, I mean, like hundreds of kilometers long, which is possible. And you would probably build this on like an island and it would, it would go out over the ocean. So that if it fell, it would just fall into the ocean. You then have, you evacuate the air from that tube, so there's no air resistance. And you put a giant chain inside, like a big, heavy metal chain. And you've got a mass driver on one end that just shoots this chain out through the vacuum of the tube. And you have magnets at the top of the tube that are deflected, repelled by this chain.

• 52:40Speaker 01

  So that the chain's momentum actually keeps the structure up.

• 52:44Speaker 00

  Ooh, that's interesting.

• 52:46Speaker 01

  It's not having to support its own weight statically. It's actually being, just like an inflatable tube man with air. It is a structure that can be dozens and dozens of kilometers tall because of this chain. And then the chain would come back down and it would be turned around, brought back, and then shot back up again. So this structure stays up because of this constantly moving, fast-moving, uh, chain. And there can be redundant chains and, there's, there are, there are ideas that are more like space fountains. Where instead of a chain, you're just shooting up like giant ball bearings. So you don't have one big thing.

• 53:21Speaker 00

  But then, hold on a second, how are you, how are you attaching panels onto the chain as it goes up?

• 53:26Speaker 01

  Yes, exactly. You're attaching them, well, not to the chain, but to the structure that surrounds the chain. And you could even, uh, electromagnetically be lifted by the chain's own momentum. And, uh, I haven't, I'm not the engineer who's done the math here, but you can lift a lot of weight this way. And you can move it at the speed that you want, get it up high enough. It's, it's certainly not orbiting, but you've gone so high that the amount of energy and the cost required to then get into orbit is a lot lower.

• 53:56Speaker 00

  Right.

• 53:56Speaker 01

  Now, I think, I think building these types of superstructures shouldn't be sci-fi. I think we're really cheating ourselves out of something amazing by just saying, ah, well, no, we'll just keep building, you know, more and more rockets. I love rockets, don't get me wrong. But I think that one of the many things humanity needs right now is a giant piece of space infrastructure that will unite us all.

• 54:23Speaker 00

  A giant floaty man tube.

• 54:27Speaker 01

  A giant inflatable tube man thing, yeah. In fact, the only comparable thing to the uniting effect of building a mega-scale piece of space infrastructure would be something like the moon landing.

• 54:42Speaker 00

  Hmm.

• 54:42Speaker 01

  I'll leave you with three quotes from people contemporaneously responding to what the moon landing meant to them. Because I think it gives us a sense of what a, a launch loop could mean to humanity.

• 54:56Speaker 00

  Go on.

• 54:57Speaker 01

  When we landed on the moon, when humans first walked on the moon back in 1969, the New York Times reached out to all kinds of notable people to get their reaction. As you can imagine, uh, almost everyone reacted with astonishment and, and wonder and pride. But Pablo Picasso was asked, and he famously said, "It means nothing to me. I have no opinion about it and I don't care."

• 55:24Speaker 00

  And juice, as always, Pablo.

• 55:27Speaker 01

  I know. I love that because when you read through, you should look this up. You can look up the New York Times from, from the day after the moon landing and they have a whole section. It's like literally two or three pages of just, here's what Jean Monet said, here's what the Dalai Lama said. And, and again, they're all really like IMAX narration, wonder of the world, um, Planet Earth-style things. Except Picasso was just like, I don't care. And then, let's not forget Charles Evers. He said, "The billions of dollars being spent on this moon exploration program means that it will be even longer before America begins to keep her promises to the poor."

• 56:07Speaker 00

  Yeah, which is always the counterargument, which is always the counterargument.

• 56:11Speaker 01

  Which is the counterargument. So I've got these two counterarguments. Um, where should I, our priorities be and why should I even care? Right? But then, this is what Paul Goodman said when he was asked how he felt about the moon landing in 1969. He said, "It's good to waste money on such a moral and aesthetic venture." These, meaning the rockets, the space infrastructure, the events, the, the adventures, they are our cathedrals. I don't think it is fair to say that they are our Roman circuses, for that is not the tone. We ought to see to it that people live well.

• 56:50Speaker 01

  But a part of living well is blowing money on big excitement, curiosity, entertainment, and conversation.

• 57:00Speaker 00

  What better argument has there ever been for a giant inflatable tube man?

• 57:06Speaker 01

  Exactly. We need to ensure that everyone lives well. But we can't forget that part of living well is blowing money on huge, exciting things.

• 57:16Speaker 00

  I have that, a, a copy of, original copy of that newspaper downstairs in a frame, that exact article that you're describing.

• 57:22Speaker 01

  Oh, do you really?

• 57:23Speaker 00

  I do, yeah.

• 57:24Speaker 01

  I've just been reading, um, scans of it on the, the New York Times machine, which is beautiful, by the way. The Times machine?

• 57:33Speaker 00

  The Times machine.

• 57:34Speaker 01

  Every time I'm researching something, I go and I see what was being said at the time by newspapers.

• 57:39Speaker 00

  I was once doing a scientific debate at Cheltenham Science Festival with a couple of astronomers. And, um, they were talking about the biggest events in history that science had given the world. And they were arguing in favor of the moon landing, right? Um, and I was, I think, in a bit of a contrarian mood. And I don't know whether I should really share this out loud. But I, I do wonder, actually, apart from sort of awe and fascination, what has the moon landing ever done for us? You know, like, don't get me wrong, I'm the type of person who buys old newspapers reporting it and puts them on my wall.

• 58:20Speaker 00

  But, you know, if you compare it to sort of the invention of antibiotics or the discovery of antibiotics or, um, I don't know, like harnessing electricity or the invention of the computer even, you know, I think that there are like some really, really big scientific moments that have fundamentally changed the future of humanity. And this one.

• 58:42Speaker 00

  Sort of didn't. I mean, it did in an emotional way and it did in a sort of awe and wonder way. And it did in a this is what humanity can achieve kind of way. But I guess it speaks to the tension that you're describing there about we need to take care of the poor before we do all of these crazy things. Because while I agree with you that actually space exploration is so endlessly fascinating, it's sort of, I, I, I want to know more. I'm completely in favor of literal blue sky research. I, I, I think this stuff is like really fundamentally important. I think, I think you're right about how it brings us together as a species. I just also see the other argument. I do also see the other argument.

• 59:20Speaker 01

  And, and so do I. I think that the answer is that we need both. Because to say, well, besides awe and fascination, what did the moon landing do for us? Is kind of like saying, well, look, besides keeping me safe and providing me with love, what has my mother done for me? She never gave me a job, you know?

• 59:42Speaker 01

  But that doesn't mean that I don't need a mom, right? Like, we need antibiotics.

• 59:47Speaker 00

  Yeah.

• 59:47Speaker 01

  We need each other, but we also need to have hope for our future.

• 59:54Speaker 00

  Agree.

• 59:55Speaker 01

  It can't be just one thing and not the others. But the whole package is part of what a good life and evolution means.

• 1:00:04Speaker 00

  You know how there's all these, I mean, particularly billionaires who are really interested in colonizing Mars? It's like, oh, well, the next step is then we colonize the moon and then we colonize Mars and so on. I've just always found there's something icky about that idea. Partly for exactly this thing that we're describing, like, why don't we actually just take care of our own planet first? But secondly, if you wanted to colonize an uninhabitable area, the Mugabe Desert is going to be way easier. Right? Like the Sahara is good. That's an absolute dottle in comparison to like, to sorting out the, the surface of Mars. I mean, you've got, aside from anything else, you've got like an abundant atmosphere of oxygen and nitrogen, which is exactly what you need.

• 1:00:47Speaker 00

  The temperature might be a bit off, but like, everything else is there. Why wouldn't you, why would you? But I think that there's something quite sort of sexy about these, these space projects. There's something like very glamorous about it.

• 1:01:00Speaker 01

  If we built a, a, a, a human colony in a desert here on earth, it wouldn't be very sexy. We would say, okay, but why did we do that? And colonizing outside of earth is very much about that bigger idea of human freedom. To be who we want to be, like a colony on Mars is so separated from earth that it can become a whole new society. It'll have its own passports, its own customs, its own culture in a way that isn't really possible anymore. Because what, 200 years ago, the frontier closed? Like, there just wasn't new space to go to. And so I think space exploration gives us that freedom again.

• 1:01:42Speaker 01

  But I also agree with the ick factor, and I'm, I'm really afraid for this in the future, which is that as space exploration becomes more and more of a private enterprise, it becomes something that doesn't belong to the people. The moon landing belonged to the people. If we want to use images from the moon landing on this podcast, we can do it for free. Because NASA's work is in the public domain because Americans paid for it. We bought it with our tax dollars. But if I want to make a video about private space flight, I've got to talk through with, with the, the legal teams there and I pay licensing fees and I can't get all the data. Whereas NASA is like, here's the transcript. We owe it to you.

• 1:02:27Speaker 01

  And that, that's what scares me the most. I'm obviously very excited about space exploration as one of the many things we should be doing. But yeah, my biggest fear is that it has become a private thing for some against everyone else.

• 1:02:44Speaker 00

  I think we shouldn't be too romantic about the, um, about the original moon landing because we, I mean, that did happen at a time when this is the biggest question at the very forefront of, of everyone's minds in America in particular, but across the globe more broadly was nuclear weapons and missiles that could be launched from space, satellite technology, observation systems and so on. And so what was happening was, um, the space race, you're right, was in the public domain, was on behalf of everybody. But it happened at this exact moment when those two things aligned, right?

• 1:03:22Speaker 00

  The, the sort of the, the, the need for, uh, defense and security in a military capacity aligned with the scientific goal. And I think that you're right that these two things now, it's become much more of a private enterprise thing, much more of a sort of, almost a status thing, really.

• 1:03:40Speaker 01

  Yes.

• 1:03:40Speaker 00

  I mean, we're going back to Katy Perry now, aren't we really?

• 1:03:44Speaker 00

  But more of a status thing because you don't have that entire nation sort of willing it forwards in the same direction as the science. Which I think was just a very particular circumstance at the time.

• 1:03:56Speaker 01

  That's right. Instead, it's being willed forward by commercial interests.

• 1:04:00Speaker 00

  Yeah.

• 1:04:00Speaker 01

  And this is what's also weird to me about AI. Not that like this podcast is now literally covering everything. But at the end of the day, a lot of these L L Ms are just corporate products. And it's not an individual. It's like a company is telling me what I want to know. As opposed to a friend who might, might have like worse ideas and less knowledge, but at least is a free individual. And so I feel that way about space exploration. Until I can take myself to space, I'm going to be beholden to something, whether it's a company or a nation. And they get to decide where I go and how and why.

• 1:04:44Speaker 01

  But the original pilgrimages were made by people who just used their own feet to go. And then they could establish a life that they wanted, not a life that fit the rules and regulations and corporate policies of the powerful.

• 1:05:02Speaker 00

  Yeah.

• 1:05:03Speaker 01

  Let us know, um, down in the comments below and also on our subreddit, The Rest Is Science. I want to hear what you guys think, especially about how do we prioritize these things? Because everyone needs to be safe here, but at the same time,

• 1:05:19Speaker 01

  there should be hope for other things coming up. Does one need to happen before the other? Can they happen simultaneously and how? I don't know. I just know that all of these puzzle pieces make something really beautiful. And if we throw a piece away, then the puzzle won't be completed.

• 1:05:36Speaker 00

  Also, guys, giant inflatable tube man, you know, let's, uh, let's, let's think about this more seriously. As ever, send us, uh, anything you like, [email protected] and we will see you next time.

• 1:05:49Speaker 01

  See you next time.

• 1:05:59Speaker 04

  Your heart can tell you a lot about your health. Apple Watch Series 12 measures your heart rate every five seconds with the most accurate heart rate sensing and wearable. So your vitals app, now with heart rate variability, can tell you when something is off. And your readiness score can let you know when to rest and when to push. Hear the story in every heartbeat with Apple Watch Series 12. The features described are for wellness purposes only and not for medical use. iPhone 11 or later required. Based on Apple conducted study of heart rate accuracy, August 2026. Visit apple.com slash apple watch series 12.

• 1:06:30Speaker 05

  Everyone's got a hard question about AI, your job, your kids, where it's going. Anthropic was built to surface those questions and share what it finds along the way. Because there's hope in hard questions. Ask yours at claude.ai slash Spotify and keep thinking. That's claude.ai slash Spotify.

• 1:06:53Speaker 06

  Stonefire Naan is made with real buttermilk and ghee. It's the perfect flatbread for any occasion.

• 1:06:59Speaker 07

  I put out Stonefire Naan with dips at every dinner party.

• 1:07:02Speaker 02

  I make naan grilled cheese when my daughter has friends over.

• 1:07:05Speaker 06

  I use Stonefire Naan to reward the humans who do my bidding.

• 1:07:08Speaker 07

  Right. It's perfect for camping trips. Dance for it, feeble mortal. Sorry, is he talking to me or? Dance. Ha, ha, ha, ha, ha.

• 1:07:19Speaker 06

  From our tradition to yours, Stonefire.

• 1:07:21Speaker 07

  Together, we Naan.