The Rest Is Science - Can Language Change What You Smell?

Episode Date: August 26, 2026

Does language shape reality? What is Earth’s escape velocity? How does soap kill germs? And can a scientific theory be completely wrong but still appear to work? In this episode of The Rest Is Science, Professor Hannah Fry and Michael Stevens (Vsauce) explore linguistics, psychology, colour perception, space travel, bacteria, viruses and the scientific method. It begins with a Persian word for a smell Hannah cannot detect on a freshly washed plate. Could having a name for something make it easier to notice? From the Sapir-Whorf hypothesis and Russian words for blue to emotions, identity and Michael’s unexpectedly large crayon collection, Hannah and Michael investigate how language may shape what we pay attention to and how we experience the world. Then, your questions. How fast would you need to throw a rock for it to escape Earth? Could it survive the atmosphere, or would it take something the size of the Chicxulub asteroid to make it out? They also uncover the ancient origins of soap, how it removes dirt and attacks some bacteria and viruses, and why getting bleach on your hands makes them feel disturbingly slippery. ------------------- 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

Hello and welcome to The Rest is Science. I'm Michael Stevens. And I'm Hannah Fry. 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. It's more of a story. But I think it will take her somewhere really interesting, you know. No, you know what? I'm going to be bold about this. It is going to take her somewhere interesting. Yes, I like that attitude. 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 mom won't let me wash up. I think it's not specific to me. Okay. She will not allow English people to wash up in her house. There is a reason. Wait, hold on. Can I guess because I married a Kiwi who lived in England for a long time.

Uh-huh. Maybe it's not just her. Do you guys just like not wash the soap off? I think I've washed pretty damn good, actually, thank you, Michael. I think I've never had any complaints before, okay? 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. Aw, 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. He's just driving himself. His eyes are bulging out. He's like tongues rolling out. Because he just cannot believe.

the beauty and the wonder of his significant other existing. Oh, Michael, that's so lovely. That's so lovely. Well, I'm a lovely guy. What can I say? It's easy for me. You can puncture it with a good surfactant. Pop some soap on it and it's game over.

Game over. Okay, so. I think she has a problem with any non-Persian doing the washing up. So what's the difference? So I think, well, this is her explanation. There is a farcey word, which I think you pronounce Zom, or Zokham, 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. This episode is brought to you by Cancer Research UK. Do you remember when we discussed why feet are so weird? Well, one particular footbone holds an even stranger's surprise. It's helping shape our understanding of cancer timelines. And for that, we're going to need to go all the way back before Neanderthals even existed

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Get tickets now. How did she clean it? She uses baking soda and cold water. Oh, wow. So she'll watch 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, I've been there,

because I know her and her mom very well, right? And I've been there, And I'm in bafflement and amazement at this Persian family who are like, but smell the difference. It's like, I cannot. And you can't, but they can. 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 micro is something I know that you also know a lot about, right? This whole area. Well, yeah. Like, the world is what it is. and then we cut it up and categorize it in our own way.

And we even 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, and 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 Ladd Bible or whatever. And it makes them go, ah, now I look like a fool because it's been named. You said it out loud. Well, it's more than just that silly example.

The Sapir-Warf hypothesis is this really well-known sociological, anthropological, psychological, psychological, psychological theory that the words you have, your vocabulary affects your ability to, to think, perceive and act in the world. That it literally changes your experience of reality when you have words with 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 to the harder ones, 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 only when we started tracking things that we changed 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 Wolf himself, really noticed he was previously a chemical engineer before he became 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 any way. He sort of didn't treat them with the respect that they deserved because they read word empty and assumed that that meant that danger just wasn't there. So the kind of strong version of this, the strong version of the Sapphire War of 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. 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. Yeah, absolutely. There's also some evidence about Russian. So in Russian, they don't have a word for just blue. They have siney, which is dark blue, like a navy color, and then Gullaboy, 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 light blue and dark blue. So it sort of looks like there, you know, there 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 just cannot plan for tomorrow, they just cannot conceive of it until they have, sort of learned to grasp tents. You know, they can't handle this idea that something will happen the next day until the future tent is something that their brains have sort of adapted to.

The reason why I'm a bit skeptical about this strong version that like, 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, the 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. 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 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, but I'm sorting through more than 100 separate colored crayons. And 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 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. Sorry, new kitten, Michael, this is, you did not consult me on this. When did this happen? 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. Amazing. 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. You can't win every battle. What kind of is Tiger's eyes? So it's like a golden rod. Okay? It's not the kind of greenish yellow of our arms.

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 green spectrum of yellow. Whoa. And I just thought so much more. And the cats seem to have so much more of a unique existence suddenly. Yeah, I do think that's true, you know. I think that words change what you pay attention to.

What you pay attention to changes your sort of existence, your experience and reality. 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 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 have two different verbs for to be. So in English, you only have the one, right? Like I am, you are. And 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 sadnesses upon me, essentially sadnesses around me. So it's like, it isn't you, you know, it's sort of like 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 ernakme, 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, you know, many, many, many centuries of sort of butting heads with the English. This is one way to put it.

Anyway, 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 clue that that's how people were feeling or is it the other way around, right, that like Irish people were feeling like that, partly at least, because their language brought them to think in that way. Do you see what I mean? Like, is it that 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'd love this stuff. It could be a little bit of both. Probably is. What are some other concrete examples? I don't remember. Well, okay, so one other example, and this is sort of a bit, well, it's definitely outside of my area of expertise, but I'm sure that there'll be people listening who maybe relate to this. But it has been said 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, 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 maybe hasn't been been relieved, but there's something quite comforting in being able to actually have a word to describe it as? Oh, for sure. Yeah, 100%. I mean, 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 past in terms of decades. And for a long time, decades had really clear names. The 20s with flappers and then, oh,

the 30s were kind of like, oh, Dust Bowl, uh, depression. And in the 40s, you had the world, you,

we have these like ideas of the, what the 50s mean, what the 60s mean, the 70s, the 80s, the 90s, and then language fails us. We don't have a catchy word for the first decade

of the 2000s. We, we have words for them. I'm not saying we don't have any. I mean, people say the naughtys. Do they? I'd say in Britain,

we do call it the naughtys quite often, yeah. The naughtys, the gnaughties. Naughty's. 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 Nottie's fashion. Until we feel comfortable calling them the tens, I don't think it'll have as strong of an identity as, say, the 60s already has. And I know that the tens are much closer to us,

and so it's hard to have that kind of reflexive perspective. We're thinking, 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 20s as a thing in our minds, but the tens, the OOs, the 19 noughties, 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, you know,

they can take on their own personalities because they're cut away by the word. Yeah. I mean, I love all this stuff. I think it's so fascinating. 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, 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. There's sort of like, there's large-scale disagreement among some linguists about this. But I think that that as we progress forward 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.

Language is describing our experience and that our experience is shaped by the language that we have. Yeah. We should make a new word, Michael, and then and thus change our experience. Not sure what it should be yet. Well, funny, and I literally have a copy of the dictionary of obscure sorrows right down here next to me. And John Tonig creates words for things that didn't have a word for them before. They can be described. But, you know, he famously is the word.

one who coined the term saunder. The feeling you get when you look at other people and realize that they have lives just as complex and consuming as you do for your own life. 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. 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 I also would say it regularly.

I think I'm going for Kulf, incidentally. Kuhl. I didn't really make it up, but I feel like Koolth should be a thing. You've got warmth, you know. We've got warmth. What about Kulth? I think Kulth should be in. Actually, you can see my bookmark, my fun little bookmark in there, tasseled bookmark.

I've been dog-earing pages that have words I like. This one, Lakotic. Lecotic 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 the thing we've all felt before, but we don't have a single word to describe it. And I think that if Lakotic became this feeling that we named all the time, we would start like doing it more often 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. You know, that's what this episode should do. I mean, all of our field notes are basically adventures in lecoticism. 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. Good idea. This episode is brought to you by Cancer Research UK. When we talk about beating cancer, we often focus a lot on survival. And that can mean overlooking

impacts that last long after treatment ends? Yeah, for example, take cancers in children and young people. The treatments themselves can be incredibly harsh. They can cause lifelong side effects like infertility or hearing loss. And Cancer Research UK is working to change that because young people, they should be able to grow up hearing the voices of the people that they love and living their lives to the fullest. That's right. And one clinical trial led by Cancer Research UK showed that giving another drug alongside chemotherapy nearly halved the number of children losing their hearing. And today, the treatment combination

is being used by doctors across the world. For more information about Cancer Research UK, their research and breakthroughs, and how you can support them, visit cancerresearchuk.org slash rest is science. Hear that? It's your money calling. It wants a promotion.

Elevate your savings with the Scotia high-interest savings account. Always earn high regular interest rates that grow the more you save and invest. Conditions apply. Visit scotiabank.com slash h-I-SA to learn more. Scotia Bank. You're richer than you think. Okay, back to some questions. We've been back on the subreddit, Michael.

You in particular are like, you're choosing a subreddit question every week, and I am here for it. So if you ask a good question on the subreddit right now, you're basically guaranteed to get Michael Stevens of Vesol's fame and rest of science fame to research a direct answer for you personally. Yeah, that's true. 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?

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. you just like barely at all okay 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 objects 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. Oh, no. That's how you mathematically calculate it. Yep.

I did not know that. 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 Earth,

it will have slowed down to just 10.27 kilometers per second. So it is traveling above Earth's escape velocity. 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 is sort of converges or diverges. It was a version of what you're describing. That was one for the murder of people, I'm sorry, but that's incredible. I had no idea.

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 fast, 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 really it's a velocity because you need to be pointed away from the earth. 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 it's going to hurt a lot. We can use rockets to escape Earth, you know, the way voyevales. 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, 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 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 per second, probably more like 20 or 30 kilometers per second, so that by the time it's out of the atmosphere, 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 out of your hand. I mean, you can't do that anyway

because we're not strong enough. But you can't do that without the immense amount 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 going to say rocks can go that fast. It was a very big rock. That was a very big rock. It was a very big rock. It was a very big rock. Big Rock. That's the secret. The Chixilube meteor was traveling 20 kilometers per second when it struck Earth. Sorry, 20 kilometers per second. 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 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 Chicksilube.

That thing, if you could throw a mountain straight up at 20 or something. 30 kilometers per second, you've done it. You've just sent a rock into an escape velocity and it's never coming back. 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 into the tube is. And then you basically fire the rock, a smaller rock, out of the tube as though it were from a gun, like a cannon. Then you would only need it to go 11.186 kilometers per second. Okay, it's actually still incredibly faster. It's still pretty high. Yeah.

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, 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.

Now, they're only able to accelerate things up to a little over two 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. The thing is, okay, so 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 way you can, like, block them together, like, their 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.

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. And, you know, whether or not this becomes the future of sending things into orbit, I don't know. But it is funny that it's a real thing that's happening.

They've, like, built some tests and they're spinning stuff up. Obviously, you have to build your satellite, not only a small, you're right to work, but it also needs to be able to withstand 10,000 Gs of force. It has to be able to spin really fast. because it's not slowly being accelerated to space. It is reaching that speed, and then it goes. 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 a capital that is raised for space projects,

I mean, it's kind of pathetically Thor. Yeah, all right. So anyway, there you go. That's how you can get a rock. 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? Amazing question, Jeff. And again, this is one of those questions where there is so much information in the question that I strongly suspect that you're actually a secret soap expert to yourself, Jeffrey. 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, so could be a positive thing when it came to controlling the spread of viruses. before we knew viruses existed at all.

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 all you need to make soap is this person called suponification. All you need is something that's alkaline, which if you just have some water on some hard wood 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, 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 sort of, they've got all of the ingredients that you need to make some soap.

It's not going to come out as a bar of imperial leather very easily, 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 their setup. Ancient Roman legend, by the way, they've got this, there was a, this story, and this is where the word soap came from, from Mount Sappel, which was the story was that this is where animals would be sacrificed and then rainwater will wash through these melted animal fats. And then the wood ashes into the river below. And then 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. Oh, really?

We don't actually think Mount Sappho ever existed. Yeah, yeah, yeah. It's a cute story. It is. But when I say this is thousands of years of, there's recipes for soap that go back 2,200 BCE. So we're talking, what, 4,000 years ago, essentially. There's Mesopotamian tablets that have got recipes. on it, it's, we've really

used this for a very long time. And I think that the idea is that actually the stuff that we cared about grind 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 molecule with two ends. It has a head that really really, really loves water and hates oil. 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, 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 down into the sink. But it also, the reason why it actually works of 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 lipid outer layer, it's called, this essentially like a fatty coat. And so if, you know, any of these bugs, any of these pathogens are in the presence of the 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 inside out. It's like phenomenally effective. And this is the reason why, you know, I remember in COVID, when everyone was like, I'll wash your hands and it was like, oh, come on, what's really going to do? But no, for real, for real, for real. Actually, that is all you need to do. Yeah. 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 where they, 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 her. It's one of the most consequential inventions our species has ever, ever made.

Yeah, you know what? Yes, yes, it is. That and the bucket. Look, Donnie Darko agrees. Wait, remind me, what does Donnie Darko do? 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. Yeah. And they're all like, that's such a weird answer. There's quite a big bit about soap in Fight Club, isn't there? Oh, yeah, right. I haven't seen that in so long. I've got the book.

I want to read the book and then watch the movie again. I did a short, a YouTube short, like Instagram real thing a little while ago about how you're too sensible to have ever done this, but I'm not. Have you ever accidentally got bleached on your hands? No, I haven't. Okay, so if you do, don't, you'll see why in the same. second. But if you do, it feels really slippery. Essentially what is happening is all you need to make soap, alkaline and something fatty. You know what's really alkaline? Bleach. You know what's 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. One of them was from people who wash the lines in pubs, right? The beer lines. And I knew this I worked in pubs like while I was doing you know all the way through uni for like seven years or something and I did know this

but I just 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 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 were still bleach in there, but what you were actually doing is turning your own skin into soap. 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. Wow. Let's do one last question. This is a really fun one. I'll let you read it. 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 proof ancient experiments like the frog and battery spring to mind. Yeah, I love that. I love that. The reasoning is off. However, the conclusion is still correct. We, I mean, the first thing I thought of was this 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, and 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 grow a bunch of crops, right?

Well, what happened was the settlers went out there 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. 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 was some bad results from that. Many, many years later 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 pulverized by dryness into a dust that would blow

away, and that's the dust bowl displaced huge amounts of people. Millions of acres of land just became completely unfarmable. My grandmother, 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 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 wow you know what this episode you've done with that this episode has 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 great dust ball of the, what was it 1930s? Yeah, it was like the end of 1930, like the, it kind of started. Wow. Which was a terrible time for a climate disaster because the stock market had just crashed.

So, you know, you couldn't grow anything, but even if you could, you couldn't sell it for much, not a great time. I think I'm going to read the grapes of wrath tomorrow on my train. There's also a great Ken Burns' Dust Bowl documentary. Ooh, yes, please. Thank you very much. Thank you very much, I will. Wow, one extraordinary example. Yeah, I mean, this is the thing, actually.

There are countless examples like this. History is sort of littered with them, false correlations, incorrect theories. And 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, 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 to, 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 were 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. I was going to say, I was going to say, That wasn't maybe the slickest ever.

How dare you? But it was done with such confidence. I loved it. It was like, oh yeah. So anyway, speaking of climate disaster, don't be a disaster yourself. Leave a comment below. I think if you commit, people don't know it's, right? Commitment is 100%.

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 in emails. The rest is science at Gollhanger.com. And we will see you next week.