How Does Language Change What You Smell?

In this episode of Field Notes, Professor Hannah Fry and Michael Stevens (Vsauce) begin with a Persian word for a smell Hannah cannot detect on a freshly washed plate. From the Sapir-Whorf hypothesis and Russian words for blue to emotions and identity, Hannah and Michael investigate how language may shape our experience of the world. Then, your questions. How fast would you need to throw a rock for it to escape Earth? What is the planet's escape velocity? Could it survive the atmosphere, or would it take something the size of the Chicxulub asteroid to make it out? How does soap kill germs? Why does bleach feel slippery on your hands? And can a scientific theory be completely wrong but still appear to work? Join them, as they explore linguistics, psychology, colour perception, space travel, bacteria, viruses and, of course, the scientific method. ------------------- 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

• 0:01Speaker 00

  Hello and welcome to The Rest Is Science. I'm Michael Stevens.

• 0:04Speaker 01

  And I'm Hannah Fry.

• 0:05Speaker 00

  And today, Hannah, you are going to show me something. I don't even know how to intro it because I'm literally seeing this for the first time.

• 0:14Speaker 01

  It's more of a story, but I think it will take us somewhere really interesting, you know? No, you know what? I'm going to be bold about this. It is going to take us somewhere interesting.

• 0:20Speaker 00

  Yes, I like that attitude.

• 0:21Speaker 01

  Yes, I'm going to be very American about this. I'm confident. Okay, so I have this, a very good friend of mine who is Iranian, and her mum won't let me wash up. I think it's not specific to me.

• 0:37Speaker 00

  Okay.

• 0:38Speaker 01

  She will not allow English people to wash up in her house. There is a reason.

• 0:43Speaker 00

  Wait, hold on. Can I guess? Because I married a Kiwi who lived in England for a long time.

• 0:49Speaker 01

  Uh huh.

• 0:50Speaker 00

  Maybe it's not just her. Do you guys just like not wash the soap off?

• 0:54Speaker 01

  I think I wash pretty damn good, actually. Thank you, Michael. I think I've never had any complaints before. Okay?

• 0:58Speaker 00

  Okay, so then I'm just like outing my wife for not rinsing the soap off enough. In my defense, or at least to make it better, look at the shirt I'm wearing. I wore this on our 10th anniversary yesterday. When I notice my significant other existing.

• 1:13Speaker 01

  Oh, that's cute. It's a picture of, I can't remember what the name of the cartoon character is, but he's bonking himself over his own head as his eyes are shooting out with hearts on them.

• 1:22Speaker 00

  He's just driving himself, his eyes are bulging out, his tongue's rolling out, ah, because he just cannot believe the beauty and the wonder of his significant other existing.

• 1:31Speaker 01

  Oh, Michael, that's so lovely. That is so lovely.

• 1:34Speaker 00

  Well, I'm a lovely guy. What can I say? It's easy for me.

• 1:37Speaker 01

  You can puncture it with a good surfactant, pop some soap on it, and it's game over.

• 1:42Speaker 00

  Game over. Okay, so.

• 1:43Speaker 01

  I think she has a problem with any non-Persian doing the washing up.

• 1:47Speaker 00

  So what's the difference?

• 1:48Speaker 01

  So I think, well, this is her explanation. There is a Farsi word, which I think you pronounce zom or zokum, maybe. People in the comments can tell us, which is a very particular word for a very particular smell that you get off plates, even after they've been washed, if they have previously contained anything raw, anything fishy, anything eggy, anything poultry-like. And they say that this, this particular smell absolutely stinks, and they do not want to go anywhere near a plate that's got any of this stuff anywhere near it. I cannot smell it.

• 2:38Speaker 01

  This episode is brought to you by Cancer Research UK.

• 2:41Speaker 00

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• 4:18Speaker 03

  This episode is brought to you by Michelob Ultra. Good times mean competitions between you and your friends, like seeing who can throw some pigskin the farthest or rush the field the fastest. Winner gets an ultra, because it's not just a superior-like beer, it's also giving fans superior access to their favorite sporting events. Superior is worth playing for. Visit michelobultra.com/superioraccess to enter. Enjoy responsibly. Copyright 2026 Anheuser-Busch InBev Michelob Ultra Beer, St. Louis, Missouri.

• 4:55Speaker 00

  How does she clean it?

• 4:56Speaker 01

  She uses baking soda and cold water.

• 4:58Speaker 00

  Oh, wow.

• 4:59Speaker 01

  So she'll wash it, like, normal, and then she'll go back around and do another round, where she uses baking soda and cold water to get it off. Like, honestly, Michael, she's, I've been there, because I know her and her mum very well, right? And I've been there, and they, I'm in bafflement and amazement at this Persian family who are like, but smell the difference. It's like, I cannot.

• 5:20Speaker 00

  And you can't, but they can.

• 5:22Speaker 01

  But they can. They all can. And here is the thing about this, okay? Because this is like the way in to, I think, something extremely interesting, which is the question of, I don't think there's anything different about our noses. I don't think there's anything different about our actual senses. But I do think that there is a question that has been raised time and time again, which is, does having a word for something make you more able to notice it? Does your sensory experience of the entire world become shaped by the language that you use? This, Michael, is something I know that you also know a lot about, right? This whole area?

• 6:05Speaker 00

  Well, yeah. Like, the world is what it is, and then we cut it up and categorize it in our own way. And we then use those labels and those categories to make sense of it and reason with it. And so if you don't have words for things, you cannot control them. I think I've talked about this before. Carl Jung talked about how like, when something is not described yet, it's terrifying. And that's why, like, calling out someone's behavior or their mannerisms really specifically can just totally diffuse the power that it used to give them. Like, oh, my gosh, you know, that was a really strong handshake. That's what an alpha male does. I read that in an article on Lad Bible or whatever,

• 6:46Speaker 00

  and it makes them go, ah, now I look like a fool, because it's been named.

• 6:51Speaker 01

  You said it out loud.

• 6:53Speaker 00

  Well, it's more than just that silly example. The Sapir-Whorf hypothesis is this really well-known sociological, anthropological, psychological theory that the words you have, your vocabulary, affects your ability to, to think, perceive, and act in the world.

• 7:11Speaker 01

  That it literally changes your experience of reality when you have words for things. And there is some, there is a bit of evidence for this. There is a bit of evidence for this. So, okay, for example, one that we've spoken about before, I mean, this is like a little bit more question marky, I guess. I'll get, I'll get to the harder ones, a bit more kind of concrete ones a little bit later. But for almost all of human history, humans were quite happy with the idea that time was cyclical. You know, you have seasons, summer and winter, morning and evening, you know, life and death. And it was only when we started inventing the calendar, when we started tracking things, that we changed

• 7:52Speaker 01

  our whole mindset and started seeing and experiencing life and time as though it was linear and marching forwards in a particular direction, right? This is like genuinely a modern invention of ours. There's also one example that Worf himself really noticed. He was previously a chemical engineer before he became this, this really notable linguist. And his job was to investigate factory fires. And he noticed something really curious, that when he was going into factories, and there were containers that were labeled as empty, people were really careless with them. They would like chuck them around, even though they still had flammable vapors in them, even though people kind of knew that they had flammable vapors in them anyway. He sort of didn't treat them with the respect

• 8:35Speaker 01

  that they deserved, because they read the word "empty" and assumed that that meant that danger just wasn't, wasn't there. So the kind of strong version of this, the strong version of the Sapir-Whorf hypothesis, says that your language determines your thought, right? If your language lacks a concept, you cannot think it, and therefore it doesn't exist to you, which is neat, but also probably wrong.

• 8:58Speaker 00

  Why do you say probably wrong? Because the most concrete convincing examples I've seen are in the realm of color perception, where if a culture has a word for a particular kind of, say, green, then they can pick that green out better than people from cultures that don't have that word.

• 9:17Speaker 01

  Yeah, absolutely. There's also some evidence about Russian. So in Russian, they don't have a word for just blue. They have sinye, which is dark blue, like a navy color, and then gulaboy, which is light blue. And if you test Russian speakers, you know, native Russian speakers against, say, English speakers, and ask them to classify colors really quickly, the Russians are much faster classifying blues, because they have this distinction in their language between, between light blue and dark blue. So it sort of looks like that, you know, there's sort of, there kind of is something there. I mean, other examples are, if you have spent time with children, you'll know that they, they just cannot plan

• 9:59Speaker 01

  for tomorrow. They just cannot conceive of it until they have sort of learned to grasp tense. You know, they can't, they can't handle this idea that something will happen the next day until the future tense is something that, that their brains have sort of adapted to. The reason why I'm a bit skeptical about this strong version, that like, that's, that's all there is. If your brain doesn't have a word for it, it doesn't exist, is that we still have inventors, you know? Inventors, mathematicians, scientists, whatever, are still able to abstractly come up with new concepts, new ideas, without there being words for them. You know, general relativity didn't have a word until after Einstein came up with it.

• 10:43Speaker 00

  I agree. A strong version that says the thing doesn't exist until it has a name, I wouldn't go along with. But I think we certainly perceive the world differently when our vocabularies change. Those Russians who were able to sort those colors faster, they are perceiving the world differently. They're attending to it differently. The same light is landing on their retinas. However, their brains, I think, at like a non-conscious level, are able to categorize and make decisions faster because the tools of language are available to them. I mean, I'm noticing this. Already in my life, not to make everything about crayons all of a sudden,

• 11:23Speaker 00

  but I'm sorting through, you know, more than a hundred separate colored crayons. And I'm, when I first started this, I'd look at Cray Yellow and Dandelion and I'd be like, well, they're the same. They're ripping us off. They're just taking the same formula, giving you a different name. But now I'm like, whoa, there's more orange in Cray Yellow. And last night, our new kitten looked at me and for the first time ever, I sort of noticed the color of its eyes.

• 11:51Speaker 01

  Sorry, new kitten, Michael. This is, you did not consult me on this. What, when, when did this happen?

• 11:56Speaker 00

  I was not consulted on this. While I was at Open Sauce, hundreds of miles away, I get this WhatsApp from my wife being like, oh, hey, we got a kitten. And I'm like, oh, what? Now, I knew that this was on the horizon. I thought we'd already agreed on a name. We were going to name it Cabbage.

• 12:13Speaker 01

  Amazing.

• 12:14Speaker 00

  If it had to come with a pair, like a sibling or a friend or something, we'd have cabbage and lettuce. But I wasn't there and now it's named Tiger. So, you know, you can't win every battle.

• 12:24Speaker 01

  You can't win every battle. What kind of Tiger's eyes?

• 12:26Speaker 00

  Uh, so it's like a, like a golden rod. Okay. It's not the kind of greenish yellow of our other cats, but I had just been like, oh, they're cat eyes and not even thought about it. Now, I was still, I think, sensing reality the way it was, but what I attend to is so controlled by the vocabulary that I have, that now that I've got all these color names, I'm able to go, whoa, I would sort your eyes more on the orange spectrum than the, the green spectrum of yellow. Whoa. And I just thought so much more. And the, and the cats seemed to have so much more of a unique existence suddenly.

• 13:04Speaker 01

  Yeah, I, I do think that's true. You know, I think, I think that, that, that words change what you pay attention to. And what you pay attention to changes your, your, your, your sort of existence, your, your, your experience of reality. There's, there's a few really interesting examples of this when you compare different languages. But then there are other people who say, well, maybe it's the other way around, right? Maybe it's not that we are, that words are shaping our experience. Maybe our experience is the thing that changes the words that we want to use. And a really nice example of this, I think, is when you look at Irish. So in Irish, they don't, they, they have two different verbs for to be. So in English, you only have the one, right? Like I am, you are.

• 13:48Speaker 01

  Um, and, uh, but in Irish, it changes depending on what the thing is doing. So if it's something that's temporary, you actually say it's on me or it's around me. So for example, tabronum is the Irish for sadness is upon me, essentially sadness is around me. Um, so it's like, it isn't you, you know, it's sort of like, it's, it exists, but it's not a fundamental part of your identity. However, if you want to say something like, I am Irish, right? Something that's like an undeniable characteristic, then you say es ernochme,

• 14:28Speaker 01

  which is like, you, there's no changing it, you know, there's no, there's no negotiation, there's no, it's that you are that and you are that absolutely fundamentally forever. And it's really interesting, I think, this stuff, because I'm just thinking about this in the context of sort of Irish resistance and, and, you know, many, many, many centuries of sort of butting heads with the English. This is one way to put it. Anyway, um,

• 14:54Speaker 01

  I do wonder whether, is it that the language has captured something that the Irish people felt about themselves and wanted to hang on to about their own identity? And that the language is the, the clue that that's how people were feeling? Or is it the other way around, right? That like Irish people were feeling like that? Um, partly at least because their language brought them to think in that way. Do you see what I mean? Like, is it that the, the words made them more, you know, more resilient, more patriotic about their own identity? Or is it that because they felt patriotic about their identity, the language then followed suit? Really, I, I love this stuff.

• 15:37Speaker 00

  It could be a little bit of both.

• 15:39Speaker 01

  Probably is.

• 15:40Speaker 00

  What, what are some other concrete examples? I don't remember.

• 15:43Speaker 01

  Well, okay. So one other example, and, and this is sort of a bit, well, it's definitely outside of my area of expertise. So, but I'm sure that there'll be people listening who, who maybe relate to this. But it has been said that, that when you have adults who are diagnosed, diagnosed with autism much later in life, that when they suddenly have the vocabulary to describe the things that they have experienced for their entire life, things like masking, you know, or stimming, um, that actually it feels like an extreme relief to suddenly be able to say, ah, that's exactly what it is. Now I understand it. And now in some ways, the sort of the pressure of it

• 16:25Speaker 01

  maybe hasn't been, been relieved, but there's some, something quite comforting in being able to actually have a word to, to describe it as.

• 16:33Speaker 00

  Oh, for sure. Yeah. A hundred percent. I mean, I've, I've talked to you about this before. This is maybe a very not concrete example, but I've thought a lot about the way we name time periods. Especially recently, we like to talk about the, the past in terms of decades. And for a long time, decades had really clear names. The twenties with flappers and then, oh, the thirties were kind of like, ah, Dust Bowl, ah, depression. And in the forties, you had the world, you, you, we have these like ideas of the, what the fifties mean, what the sixties mean, the seventies, the eighties, the nineties. And then language fails us. We don't have a catchy word for the first decade of the two thousands.

• 17:18Speaker 00

  We, we have words for them. I'm not saying we don't have any.

• 17:21Speaker 01

  I mean, people say the noughties.

• 17:22Speaker 00

  Do they?

• 17:23Speaker 01

  I'd say in Britain, we do call it the noughties quite often. Yeah.

• 17:26Speaker 00

  The, the noughties, the naughties.

• 17:28Speaker 01

  Naughties.

• 17:29Speaker 00

  Okay. So if naughties really caught on, then I think it would take on a much more concrete existence in our minds. And it would be very clear what was and wasn't naughties fashion. Until we feel comfortable calling them the tens, I don't think it'll have as strong of an identity as say, the sixties already has. And I know that the tens are much closer to us. And so it's hard to have that kind of reflexive, um, uh, perspective where things get sort of simplified and turn more into like their prototypical examples. But I think that the 1900s show this too. Like we have the twenties as a thing in our minds, but the tens, the OO's, the, the, the nineteen naughties?

• 18:14Speaker 00

  Like what are they? They don't have as much of an identity. And there's a lot of factors that make that be the case, the cultural mass production, all these things. But I think that language alone allows us to grab things and they can take on their own personalities because they're cut away by the word.

• 18:32Speaker 01

  Yeah. I, I mean, I love all this stuff. I think it's, it's so fascinating. Um, it's also just an ongoing area of debate because there are other people, Chomsky is a really great example of this, who is like, no, no, no, no, no. No, it's not like that at all. This is something that is innate in your brains. The language is just the way that it's finding, it's sort of finding out. The sort of like, there's, there's, there's large scale disagreement among some linguists about this. But I think that, that as we progress forwards in time, it's sort of the way that these things tend to go. I think it's like, it's sort of a bit of both, that language is describing our experience and that our experience is shaped by the language that we have.

• 19:08Speaker 00

  Yeah.

• 19:09Speaker 01

  We should make a new word, Michael, and then, and thus change our experience. Not sure what it should be yet.

• 19:13Speaker 00

  Well, funny, I, I literally have a copy of the dictionary of obscure sorrows right down here next to me. And John Chonig creates words for things that didn't have a word for them before. They can be described, but you know, he famously is the one who coined the term sonder. The, that feeling you get when you look at other people and realize that they have lives just as complex and, and consuming as you do for your, for your own life. Um, but I mean, gosh, I just, this is a book that like, it takes me forever to read because I need to spend a whole day thinking about each one.

• 19:48Speaker 01

  When I was younger, that was my number one ambition actually, was to have a word, a word that I made up in the English dictionary. I mean, it was sort of a joke, but it, I also would say it regularly. I think I'm going for coolth, incidentally. That's, that's what I want. I didn't really make it up, but I, I, I feel like coolth should be a thing. You've got warmth, you know?

• 20:06Speaker 00

  We've got warmth. What about coolth?

• 20:08Speaker 01

  I think coolth, coolth should be in.

• 20:10Speaker 00

  You know, actually you can see my bookmark, my fun little bookmark in there, tassel bookmark. I've been dog earring pages that have words I like. This one, locatic. Locatic is an adjective. And what it means is anxiously excited to introduce a friend to something you think is amazing. A classic album, a favorite restaurant, a TV show they're lucky enough to watch for the very first time. And that's a thing we've all felt before, but we don't have a, a single, single word to describe it. And I think that if, if locatic became this like feeling that we named all the time, we would start like doing it more often and, and, and preparing for it. And there'd be more ritual around it. But without the word, it's just kind of a thing that happens and then flows away.

• 20:54Speaker 01

  You know, that's what this episode should do. I mean, all of our field notes are basically adventures in locaticism.

• 21:00Speaker 00

  Isn't that true? What a coincidence. Ooh, it's a little bit spooky. So let's, let's explore some new things by looking into some questions that came in from you guys after the break.

• 21:10Speaker 01

  Good idea.

• 21:24Speaker 00

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

• 22:27Speaker 03

  This episode is brought to you by Michelob Ultra. Good times mean competitions between you and your friends, like seeing who can throw some pigskin the farthest or rush the field the fastest. Winner gets an ultra. Because it's not just a superior light beer, it's also giving fans superior access to their favorite sporting events. Superior is worth playing for. Visit michelobultra.com/superioraccess to enter. Enjoy responsibly. Copyright 2026 Anheuser-Busch InBev Michelob Ultra Beer, St. Louis, Missouri.

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• 23:34Speaker 01

  Okay, back to some questions. We've been back on the subreddit, Michael. You, in particular, like, you're choosing a subreddit question every week, and I am here for it. So, if you ask a good question on subreddit right now, you're basically guaranteed to get Michael Stevens' obvious source fame and Rest is Science fame to research a direct answer for you personally.

• 23:56Speaker 00

  Yeah, that's true.

• 23:58Speaker 01

  It says, "At which speed would you need to throw a rock for it to be able to overcome the friction of the atmosphere, leave the planet, and the gravitational pull of the Earth?"

• 24:07Speaker 00

  Yeah, I love this question. It comes from Din Reddit. Thank you for this, because I learned something very cool and new about escape velocity. I thought of it very naively until now. I thought, oh, yeah, you leave Earth's gravity. And that's how, even in this question, it's described: leave the planet and the gravitational pull of the Earth. I never once questioned, wait a second, that's impossible, though. No matter where you are in the universe, Earth's gravity is affecting you. You know? You could be on the other side of the galaxy, and still, Earth's gravity is affecting you, just like barely at all, okay?

• 24:48Speaker 00

  But like, I've done, I've done videos about the effect that your birth had on the rings of Saturn gravitationally. It can be calculated, right? And yet, I never once thought, well, wait a second, what is escape velocity, then? And here's the answer. When we calculate escape velocity, what we're really saying is, okay, if you're going really fast, you've got some speed, the gravitational force of some other object, say the Earth, is slowing you down. Well, you have reached the escape velocity for that gravity well if the object cannot slow you down to zero until you are infinitely far away.

• 25:30Speaker 01

  Oh, no.

• 25:31Speaker 00

  That's how you mathematically calculate it. Yep.

• 25:34Speaker 01

  I did not know that.

• 25:36Speaker 00

  That's what it means. Because when you're seven light years away, Earth is still decelerating you, just not as much as before. You're constantly being slowed down. For example, Voyager 1 is right now traveling at about 17 kilometers per second. But when it is, and this is of course all mathematical, when it is infinitely far away from our solar system, from, from Earth, it will have slowed down to just 10.27 kilometers per second. So it is traveling above Earth's escape velocity.

• 26:08Speaker 01

  That is so interesting, because I'm thinking, I tell you what, inevitably, I'm thinking here about arithmetic and geometric series, right? And essentially, it's about whether this sort of converges or diverges, whereas a version of what you're describing, that was one for the nerdier people, I'm sorry, but that's incredible. I had no idea.

• 26:27Speaker 00

  Yes, and it's very cool, because it finally made sense in my mind about what it means to escape when you can't actually escape gravity anywhere. All it means is that you're fleeing at such a fat, you have such a fast initial speed that as you decelerate, you will not reach zero until you're infinitely far away. So we need to give something that speed. I'm saying speed, but we're assuming that really it's a velocity, because you need to be pointed away from the, the Earth. If you're, if you're moving at a speed at which you can escape Earth, but you're going down, you won't escape Earth. So it is a velocity. But anyway, the point is.

• 27:03Speaker 01

  It's gonna hurt, it's gonna hurt a lot.

• 27:04Speaker 00

  We can use rockets to, to escape Earth, you know, the way Voyager has, but we don't need to go really fast right away. We can just constantly keep burning fuel, or in Voyager's case, zip around Jupiter, give yourself a little slingshot speed. But if you want to throw a rock, the rock doesn't have any fuel or propellant, it can't keep accelerating. So you need to give it all the speed it needs right away. And at the surface of the Earth, that escape velocity is 11.186 kilometers per second. That's about 25,000 miles per hour. If you have that speed, and you're pointing away from Earth, so you have the right velocity,

• 27:46Speaker 00

  then Earth will keep slowing you down, but it will not slow you down to a standstill until you're infinitely far away. Perfect. So that's what you need to do. No, because if you threw a rock that fast, it's got air in the way, and it will explode. Moving that quickly, it's going to compress the air in front of it into a plasma, and the entire rock will blow up. So unfortunately, that's a problem. Also, I mean, even if, even if we somehow invent a material that can survive those temperatures, the drag of the atmosphere will slow it down. So you can't throw the rock at 11.186 kilometers per second. You've got to throw it, depending on how aerodynamic it is, at least like 13, 14 kilometers

• 28:28Speaker 00

  per second, probably more like 30, 20 or 30 kilometers per second, so that by the time it's out of the atmosphere, it's, it's, it hasn't been slowed down so much that it falls back down to Earth. But you definitely cannot throw a rock at, say, 20 kilometers per second, right off of, right out of your hand. I mean, you can't do that anyway, because you're not strong enough. But you can't do that without the, the immense amount of, of energy and heat created through friction with the atmosphere destroying the rock. Or can you? Okay? Don't tell me it's not possible. Go ask the dinosaurs. They're gonna say rocks can go that fast.

• 29:04Speaker 01

  It was a very big rock. That was a very big rock.

• 29:07Speaker 00

  It was a very big rock. That's the secret. The Chicxulub meteor was traveling 20 kilometers per second when it struck Earth.

• 29:16Speaker 01

  Sorry, 20 kilometers per second?

• 29:18Speaker 00

  20 kilometers per second at impact. It spent an eye blink, well, not really, it spent like five seconds in the atmosphere total. But here's the thing, that obviously was a huge energetic explosive event, but the darned meteor was so large, it only lost 1% of its mass traveling through our atmosphere. If you, if you threw a house-sized rock up into our atmosphere, it wouldn't make it. The whole thing would get destroyed, it would create what's known as an airburst. This happens with meteors that are the size of houses all the time. But a mountain-sized rock, I'm talking 10 kilometers wide, that's the size of Chicxulub,

• 30:02Speaker 00

  that thing, if you could throw a mountain straight up at 20 or 30 kilometers per second, you've done it. You've just sent a rock into an escape velocity, and it's never coming back.

• 30:14Speaker 01

  Okay, okay, I've got an easier way. What about if you create a tube that goes up 100 kilometers, and you create a perfect vacuum inside the tube? I'm not sure what the structure of the tube is. And then you basically fire the, the rock, a smaller rock, out of the tube as though it were from a gun, like a cannon?

• 30:33Speaker 00

  Then you would only need it to go 11.186 kilometers per second.

• 30:37Speaker 01

  Okay, it's actually still incredibly fast, all right.

• 30:39Speaker 00

  It's still pretty high, yeah. The thing, the thing about the air drag is that you only, if you're aerodynamic enough, you don't need to go that much faster, because when you're going that fast, you're just not in the atmosphere very long. You're not being slowed down by it for very long. But, I mean, this, this like vacuum, like evacuated chamber throwing things is already a real project called Spin Launch. This company called Spin Launch is creating these, these big centrifuges that spin things around in a vacuum until they reach this really, really immense speed. And then they like basically open a hatch and let go of it, and it flies out tangential to its original spiral path, and it goes up.

• 31:22Speaker 00

  Now, they're only able to accelerate things up to a little over 2 kilometers per second, so the things they're accelerating are rockets. And once it gets up really high, boom, it turns on its chemical propulsion and goes the rest of the way. But we're not allowing that. We're just doing this with a rock, just a piece of rock that has no fuel. It's got to have that full speed right off the bat.

• 31:46Speaker 01

  Thing is, okay, so I went to this, I went to this lab in Singapore where they were essentially sending up very, very, very modern satellites. These things were like, they were like this big, they were like rock-sized, essentially. And like, they were saying, this is sort of the future of space, because actually, you don't need to be this gigantic thing, it's really expensive, blah, blah, blah, blah, blah. This, this way, you can like block them together like they're Lego, you can sort of send them up really easily, off you go. I had no idea that people were using the like spin it around and fling it trick.

• 32:17Speaker 00

  Yeah, well, Spin Launch raised an enormous amount of money. Like, I'll have to look it up, but it was like north of $100 million. And there's, there's been a lot of discussion about how like, oh gee, I think Spin Launch sort of came about at a time when everyone wanted to invest in space, but there wasn't anyone to invest in, so all the money went to them. Um, and you know, whether or not this becomes the future of sending things into orbit, I don't know, but it is, it is funny that like, it's a real thing that's happening. They've, they've like built some tests and they're spinning stuff up. Obviously you have to build your satellite, not only a small, right, to work, but it also needs to be able to withstand 10,000 Gs of force.

• 33:01Speaker 00

  It has to be able to spin really fast, um, cause it's, it's not slowly being accelerated to space. It is reaching that speed and then it's, it goes.

• 33:11Speaker 01

  Neil, who's our producer, has just sent a message saying that they've raised $230 million in funding so far, which sounds like a lot of money, but actually when it comes to capital that is raised for space projects, there's, I mean, it's, it's kind of, it's kind of pathetic, Lewis.

• 33:27Speaker 00

  Yeah. All right. So anyway, there you go. Uh, that's how you can, uh, get a, a rock, uh, to, to leave the earth. Next question comes from Jeff, who asks, soap. Who thought it would be a great idea to plunge their dirty hands into a mix of boiled down hooves and something alkaline? If the idea is ancient, i.e. before germs were invented, invented, I love that, what was the purpose of it? Does soap kill germs or just wash them away to be someone else's problem? Do bacteria and/or viruses develop resistance to soap?

• 34:01Speaker 01

  Amazing question, Jeff. And again, this is one of those questions where there is so much information in the question that I strongly suspect, strongly suspect that you're actually a secret soap expert yourself, Jeffrey. Um, okay. So, I mean, Jeff is absolutely right that soap has been around for thousands of years, way before we knew germs even existed, way before there was germ theory, way before we understood that like viruses could be, could, soap could be a positive thing when it came to, um, to, to controlling the spread of viruses, before we even knew viruses existed at all. Um, and actually I think this is one of those inventions, a bit like glass, where it's like, you can sort of imagine the circumstances which led to its discovery, because actually

• 34:45Speaker 01

  all you need to make soap is this process called saponification. All you need is something that's alkaline, which if you just have some water on some hardwood ash, that'll do it, that'll do it. So you have a fire and then it rains, you know, that's it. You've got your alkaline right there. And then the other thing that you need is something fatty, something with fat in it. So it could be, you know, some like discarded animal detritus, you know, if you've, if you, essentially if you imagine that you are cooking over a fire, right? You're kind of like burning meat over a fire and then you finish and you leave some bones by the fire, the fire burns out and it rains the next morning, somewhere in there, somewhere in there, it's, it's sort of, they've got all of the ingredients that you need to make

• 35:30Speaker 01

  some soap. It's not going to come out as a bar of imperial leather very easily, but, but all of the stuff is there, the kind of, the stuff is there that exists naturally. So we don't know exactly where people discovered this, but you can kind of imagine the setup. Ancient Roman legend, by the way, they've got this, there was a, this, this story, and this is where the word soap came from, uh, from Mount Sapo, which was, the story was that, that this is where animals would be sacrificed and then rainwater will wash through these, these melted animal fats and then the wood ashes into the river below. And then the, the story is that this soapy mixture, you would go to this river and it would wash your clothes really brilliantly, you know, your skin would come out really clean.

• 36:13Speaker 00

  Oh, really?

• 36:14Speaker 01

  We don't actually think Mount Sapo ever existed.

• 36:16Speaker 00

  Yeah, yeah, yeah.

• 36:17Speaker 01

  It's a cute story.

• 36:18Speaker 00

  It is.

• 36:19Speaker 01

  But when I say this is thousands of years old, that, that there's recipes for soap that go back 2200 BCE, so we're talking, what, 4,000 years ago essentially. There's Mesopotamian tablets that have got recipes on it. It's, uh, we have really used this for a very long time. And I think that, that, that the idea is that actually the stuff that we cared about, grime that you can see, you know, if there's something floating around and you're playing around with it and it just happens to make your hands clean, of course you're going to investigate what it was that gave rise to that process in the first place. The reason it works, by the way, the reason why soap is so good, is that it's this, it's this molecule with two ends. It has a, a head that really, really loves water and hates oil.

• 37:04Speaker 01

  And it has a tail that really, really loves oil and hates water. It's kind of like this double ended molecule. So essentially what happens when you're like washing dishes, for instance, um, the tails that are like looking for the oil, they sort of dive their tails into any oil that appears and then they form this sort of like this cluster around a blob of oil and then that can just then be washed away, uh, down into the sink. But it, but it also, the reason why it actually works with bacteria and viruses is that so many of the nastiest things that infect us, so, you know, HIV, hepatitis B, Ebola, Zika virus, loads of bacteria, all of this stuff, they have this like, this, this lipid outer

• 37:47Speaker 01

  layer, it's called, this essentially like a fatty coat. And so if you, you know, any of these bugs, any of these pathogens are in the presence of soap, what soap will do will be to dive its tails into this coat and as it does so, it rips it apart, sort of like tears apart the virus or the bacteria from, from inside out. It's like phenomenally effective. And this is the reason why, you know, I, I remember in COVID when everyone was like, oh, wash your hands and it was like, oh, come on, what's it really going to do? But no, for real, for real, for real, actually that is all you need to do.

• 38:21Speaker 00

  Yeah.

• 38:22Speaker 01

  It's all you need to do. Like soap is this miracle, miracle discovery. How lucky are we that soap turns out? I mean, goodness knows whether, like, how many lives soap has actually saved across the entire history of humanity by being this incredible defense against the things that are most harmful to us.

• 38:39Speaker 00

  It's one of the most consequential inventions our species has ever, ever made.

• 38:45Speaker 01

  Yeah. You know what? Yes. Yes, it is. That and the bucket.

• 38:50Speaker 00

  Uh, look, Donnie Darko agrees.

• 38:51Speaker 01

  Wait, remind me, what does Donnie Darko do?

• 38:52Speaker 00

  That's, that's a little reference for the true fans. Basically, there's a scene in the movie where he's asked like, what's the most important invention? And he's like, soap.

• 38:59Speaker 01

  Yeah.

• 39:00Speaker 00

  And they're all like, that's such a weird answer.

• 39:01Speaker 01

  There's quite a big bit about soap in Fight Club, isn't there?

• 39:04Speaker 00

  Oh, yeah, right. That's, I, I, I haven't seen that in so long. I'm, I've got the book. I want to read the book and then watch the movie again.

• 39:12Speaker 01

  I did a, um, I did a short, a, a YouTube short, like Instagram reel thing a little while ago about how, um, you're too sensible to have ever done this, but I'm, I'm not. Have you ever accidentally got bleach on your hands?

• 39:23Speaker 00

  No, I haven't.

• 39:25Speaker 01

  Okay. So if you do, don't, you'll, you'll see why in a second. But if you do, it feels really slippery. Essentially what is happening is, um, all you need to make soap, alkaline and something fatty. You know what was really alkaline? Bleach. You know what was really fatty? Your fingers. So you are literally turning your fingers into soap. Now, when I posted this video, there was loads of comments from people and one of them was from, um, from people who wash the lines in pubs, right? The beer lines.

• 39:56Speaker 00

  Ah.

• 39:57Speaker 01

  And I knew this, I used to, I worked in pubs, like while I was doing, you know, all the way through unis for like seven years or something. And I did know this, but I just, I completely had escaped my mind. But what you used to do was you would put bleach through the lines to sort of, you know, kill everything. And then to make sure that the bleach had washed out, you would put your hand in the, the, the, sort of, as you're washing it through, you would put your hand in it. And if it felt slippery, you would know that there was still bleach in there. But what you were actually doing.

• 40:28Speaker 00

  Is turning your own skin into soap.

• 40:31Speaker 01

  And then when the process of turning your own skin into soap stopped, you knew that you were ready to put the beer back in.

• 40:36Speaker 00

  Wow. Let's do one last question. Uh, this is a really fun one. I'll let you read it.

• 40:42Speaker 01

  Okay. Oh, I don't know who it's from actually. Let's say anonymous, but if it isn't, then you can write in and tell us off. Okay. Given that heat makes things expand, I deduce that this is why days are longer in the summer. Are there any papers or theories that ended up completely misunderstanding what they set out to prove? Ancient experiments like the frog and bacteria spring to mind.

• 41:00Speaker 00

  Yeah, I love that. I love that, like the reasoning, um, is, is off, however, the conclusion is still correct. Wait, I mean, the first thing I thought of was this, uh, now very discredited theory of climatology, which is called rain follows the plow. So in the 1860s and 70s, settlers were moving out west in the United States. And if you look at a satellite picture of the United States, you'll see that there's this line around the 100th meridian where it just goes from being really green to really not green, like suddenly very dry, not a good place to like grow a bunch of crops, right? Well, what happened was the settlers went out there.

• 41:42Speaker 00

  And then they started to report that things were getting greener, that it was wetter. And one of the theories was that if people go, the water comes. Rain follows the plow. If you need water for your crops, just plant them anyway. The act of plowing and planting and human activity causes rain. So go ahead, settlers, like move out there, build the farms. And so this wasn't just like an old wives tale or something. This was like scientists, people at the University of Nebraska were like, yeah, this is a permanent change. Something's happening. It could be that when we plow the ground, the surface area of dirt exposed means that more moisture gets up.

• 42:25Speaker 00

  It could be that the smoke and the steam from the locomotives is affecting this. It could just be that the sounds of human activity and human voices causes cloud formation. Like, it's fine. And this was a very believed thing. Turns out, no. It was just a temporary wet few years. And as we all know, there were some bad results from that. Many, many years later, in the, in the 30s, the very beginning of the 1930s, drought came, as it often would, and farmers had removed topsoil. They'd removed the root structures of grass. And suddenly the soil just got like pulverized by dryness into a dust that would blow away.

• 43:07Speaker 00

  And that's the Dust Bowl displaced huge amounts of people. Millions of acres of land just became completely unfarmable. My grandmother, on my, on my mom's side, was born in California because her family in Missouri just could not live there until things got better. And then, you know, she moved back, met my grandpa. And so I grew up in that same area. But that was, it's very funny to read these like scientific papers about how like, you know what? There's not enough rain there unless we start wanting rain and we plant things anyway, and then it brings the rain.

• 43:41Speaker 01

  Wow. You know what? This episode, you know what you've done with that? This episode's done like a nice little, tied it up in a little bow at the end because we started with the Dust Bowl, like different decades having different themes, different sort of like, you know, the, the like, the great Dust Bowl of the, what was it, 1930s?

• 43:59Speaker 00

  Yeah, it was like the end of the, of 1930, like the, it kind of started.

• 44:03Speaker 01

  Wow.

• 44:04Speaker 00

  Which was a terrible time for a climate disaster because the stock market had just crashed. So, you know, you, you couldn't grow anything. But even if you could, you couldn't sell it for much. Not a great time.

• 44:14Speaker 01

  I think I'm going to read The Grapes of Wrath tomorrow on my train.

• 44:17Speaker 00

  There's also a great Ken Burns Dust Bowl documentary.

• 44:21Speaker 01

  Ooh, yes, please. Thank you very much. Thank you very much. I will. Wow, what an extraordinary example. Yeah, I mean, this is the thing, Ashley. There are, there are countless examples like this. History is sort of littered with them. False correlations, incorrect theories. And this is, this is one of the main reasons why science is not about finding something that proves your theory. I think this is one of the great misconceptions about what science is and does. Science is never about finding evidence to support your theory. Because if you do that, that's the situation that you end up in. Instead, science is like the opposite. Science is saying, if you have a theory,

• 45:03Speaker 01

  you do everything you possibly can to disprove it. And then if you fail, if you throw everything you have at it, if you are like, go at it with kind of real honesty and integrity and try and disprove your theory and fail, then maybe there's evidence to suggest that your original theory was correct. But, I mean, actually, to be honest, the time that you're talking about, the 1930s, is kind of modern ideas of science were only really in their infancy around that time. Well, look, we love the scientific method, but we also love you, our listeners. And we love the questions that you send us. So please do send us more. We're getting slick with these links.

• 45:44Speaker 00

  I was gonna say, I was gonna say, that wasn't maybe the slickest ever.

• 45:48Speaker 01

  How dare you?

• 45:49Speaker 00

  But it was done with such confidence. I loved it. It was like, oh, yes. So anyway, speaking of climate disaster, don't be a disaster yourself. Leave a comment below.

• 45:58Speaker 01

  I think if you commit, people don't notice, right?

• 46:01Speaker 00

  Commitment is 100% that, you know? It's not even like a 91. I second what Hannah said. Follow us on YouTube or wherever you get your podcasts. Leave us some comments. Join us on the subreddit. Send us an emails. The rest is [email protected].

• 46:17Speaker 01

  And we will see you next week.

• 46:33Speaker 06

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