The Elegant Laminar Flow Of Moroccan Tea

16:26Michael Stevens:Yeah, that's right. I love the folk physics of it. The like, look, if you warm the metal up, and then you cool it down quickly, it's going to be softer. And we call that annealing. And today you can look up a bunch of videos about exactly what's happening at a molecular level and why. But before that was really understood before atomic theory, before molecular theory, it was just like the metal has a personality and you have to treat it this way. You have to be mean and then tender. And I can see how much more alive the world was when you had to just make everything an animal. And yet, it still gave you the right answer.

17:00Michael Stevens:I mean, maybe it didn't allow you to fiddle with numbers a little bit and develop whole new hardnesses of steel, but you would discover them on accident. And it was like a blessing.

17:10Hannah Fry:Exactly. I think this is it, actually. The sum total of human knowledge, even without science, is just really profound. There's this Japanese idea, actually, that in a single cup of tea, you'll eventually discover the truth of 10 ,000 forms in the universe, right? Like this idea that you can observe all of humanity in a single cup of tea.

17:38Michael Stevens:And it's not that far off. A single cup of tea gives us thermodynamics, fluid dynamics. It gives us history and botany and human culture and tastes and flavors. It's all there.

17:54Hannah Fry:It's all there. There you go, Michael. That's me spilling the tea. Maybe less juicy than you might have been expecting, but more fluid dynamics. All right. Should we go to a break and then we'll come back to some of your questions after?

18:12Hannah Fry:No one goes to Hank's for his spreadsheets. They go for a darn good pizza. Lately, though, the shop's been quiet, so Hank decides to bring back the$1 slice. He asks Copilot in Microsoft Excel to look at his sales and costs and help him see if he can afford it. Copilot shows Hank where the money's going and which little extras make the$1 slice work.

18:33Michael Stevens:Now Hank's has a line out the door. Hank makes the pizza.

18:37Hannah Fry:Copilot handles the spreadsheets. Learn more at m365copilot.com slash work.

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19:24Michael Stevens:Terms and conditions apply.

19:35Michael Stevens:And welcome back. Hannah and I are now going to delve into questions that you all have sent us. We certainly are. Do you want to go first, Michael? I took the first half. Yeah, I'll go first because I love this question from Lewis Taylor. The question is, the boiling point of water is affected by your altitude, which we tend to measure as a height above sea level. But if sea level changes outside of its normal range, will that change the time it takes to boil water and therefore eggs? And I love this because, one, it's very personal to me because I spend time pretty much at sea level in L.A., but also up over 5 ,000 feet in Boulder, Colorado.

20:12Michael Stevens:And you notice a difference. I have to now remember two different times for soft-boiled eggs. Like here in L.A., it's like five minutes. We're getting too far. But I need to do six and a half in Boulder. and you can measure the water temperature and it's like, oh, wow, this boiling water is not 212. You know, it's like, let me see, temp of boiling water, Boulder, Colorado. Yeah, the water boils in Colorado in Boulder at 203 Fahrenheit.

20:43Hannah Fry:Translate that into a sensible

20:45Michael Stevens:system for me, could you? In C is 95. Whoa. So water boils at 95 degrees Celsius in Boulder. And that means that to cook an egg, like to soft boil or hard boil it, it just needs to be in that water a lot longer, like a couple minutes longer, at least. And pasta is the same way. You know, normally pasta instructions would be like 10 to 12 minutes. Boil this to be soft. And I would go just to like 10 or even under the minimum. But in Boulder, I've got to go past the maximum. And it's still not even al dente. It's still like too hard.

21:21Hannah Fry:I think that you would, I think you'd particularly notice that too, given that for some strange reason, Americans don't have kettles. I've always found that the weirdest thing about your country.

21:31Michael Stevens:I can't say too much about it, though, because my mother had a kettle. Oh, my wife. I married a Kiwi who lived in England for decades. So she's got an electric kettle in our house and we use it all the time. So, look, I get what you're saying, though. It takes even longer to boil water when you don't have like a super fast turbo electric kettle. But yeah, I think constantly about how my altitude is the reason the water is taking longer to boil. Long story short, there's just less air above you when you're already up in a mountain. And it's that water's, sorry, it's the air's weight that's pushing down on the water molecules saying, no, you cannot leave your liquid state.

22:14Michael Stevens:You cannot leave this container. And if you go up high enough, there's so much less weight from that air squeezing on top that the water molecules can get out more easily. They don't have to have as much energy to leave the liquid state so that it boils with a lower temperature with less kinetic energy. And I always think of my altitude in terms of a number like 5000 feet or whatever. And that's from sea level. But if sea levels go up, like let's say I live at 5000 feet, if the sea levels rise by a foot, do I now live at 4999 feet? technically I do. But what happens to the actual air pressure effect on boiling?

23:01Michael Stevens:And I think that's a lot more complicated. And I think first of all, the ice and it tell me if I'm wrong, because this is just me kind of noodling through it. The ice that melts that then causes the sea level to rise took up more volume than the water does. I know that a lot of glacial ice is much more dense than the typical ice that we'll put in a drink. But I think that overall, the amount of space taken up by solid matter on Earth goes down when sea levels rise because you've exchanged some liquid water. Well, you've exchanged some solid ice for some liquid water.

23:41Hannah Fry:Which is a smaller volume. But crucially, you have a hell of a lot of water in glaciers on land that could be added to that total.

23:53Michael Stevens:Yes, but if a glacier on land melts, the total volume of solid material on Earth has gone down because it's turned from ice to water. and so in that way the average height of earth like what we call mean sea level would well but mean sea level is based on where the oceans are floating but you got to imagine that all the solid stuff on earth is displacing the air and when the solid stuff that's displacing the air gets smaller you now have what a thicker atmosphere or a thinner?

24:33Hannah Fry:I see where you're going with this. Isn't there an additional complicating factor, which is that there is a huge amount of gas also trapped within glaciers so that once that ends up melting, there's a higher amount of air.

24:52Michael Stevens:Of air overall. Right. Let's just do like a toy model and let's imagine that the earth becomes smaller, like half the diameter but it has the same amount of air now we're really exaggerating this change but that same amount of air is now going to be much thicker everywhere the atmosphere is thicker because it's got a smaller um surface to cover hang on let me make sure i'm following you

25:19Hannah Fry:you take you take the sphere of earth and you shrink it so that it's half the size yeah and you keep all the same air around all the same air so air are we saying that the outer like the carmen line as it were effectively is like is in the same place or is the whole thing shrinking

25:37Michael Stevens:i think that the only the solid part of earth shrinks so i think the carmen line would go up because you've got the same amount of air okay so imagine you've got like a cake that's a that's really big and you've got one jar of frosting, you can cover the whole cake, but it's a thin layer. Now you make the cake half the diameter, but you have the same amount of frosting. It's going to be a thicker layer. So air pressure, frosting pressure in our example here is going to be greater now at each point on the cake surface because there's a higher column of frosting above you than when you were a big cake with a thin layer.

26:16Michael Stevens:Let us know in the comments below what I'm getting wrong, because I am just noodling on this. And I'm thinking that if the total volume of solid stuff that Earth is made of shrinks, like the total amount of mass I'm imagining stays the same, the volume gets smaller, the air pressure would increase. But I think there's also so many complicating factors like could the atmosphere become thicker? Or is it going to start getting picked off more quickly by solar wind or something? Like I think when we talk about sea level rising one foot, we're probably talking about such a small change that other consequences might compensate extra air release from melting glaciers, thicker atmosphere being pulled off by solar wind.

27:02Michael Stevens:There might not be much of a change. But if all that happened was that Earth technically had a smaller volume, I think that the boiling point of water would go up, regardless of the fact that your altitude above sea level went down.

27:16Hannah Fry:I like this so much. This feels like, this almost feels like a, you know, when they do those incredibly hard interview questions.

27:24Michael Stevens:Yes. Yeah. How many ping pong balls are here in New York City? Yeah.

27:28Hannah Fry:Right. Exactly. Or like if you were a flea trapped in a blender, how would you get out? Like if you were shrunk down to the size of a flea and put into a blender, right? That kind of thing, you know? Yeah. This is, I want to think about this. I want to think about this. Maybe in the comments as well, you can tell us your answers. And maybe we'll come back to this in another episode of Feel Notes and we'll compare. Because I think there's an argument that it's the opposite. But, you know, I want to get my equations on before I commit. Yeah, yeah, yeah.

27:57Michael Stevens:Using no equations or anything, just straight up what I know about stuff and comparing stuff to cake, sometimes very helpful. I think that all else being equal, if sea levels rose because of melting glaciers and ice caps, technically, the boiling point of water everywhere would be a little higher, despite the fact that your altitude above sea level will have gone down because mean sea level will be closer to you.

28:23Hannah Fry:I'll tell you what, there was a question I really liked the look of by Ole Stierne. That's my best possible attempt at the pronunciation. And I think this links in quite nicely with this because here's a question. I was watching some climbing videos on YouTube and it made me wonder what percentage of naturally occurring vertical surfaces on land that are on land have actually been traversed by humans. What a great question. So I had a little go at this, at calculating it. And a sort of related question that I have wondered so many times is how much of horizontal surface has ever seen a human footprint?

29:04Hannah Fry:Like when you go out and you're kind of walking the land, how much of earth has no human footprint ever laid upon? This is sort of, I mean, this question about earlier is like the vertical version of this, I guess and that one does have a clear answer right so I'll tell you this well clearish answer because I think that humans you sort of I think it's very easy to feel like we're spread out all over the place that we've kind of dominated the entire planet but the reality is we're actually a really huddled species so if you take all urban infrastructure everything that we've built and live in, it's actually only 1 % of land.

29:45Hannah Fry:It's tiny, teeny, teeny, tiny.

29:47Michael Stevens:Which is an even smaller percentage of Earth's surface.

29:51Hannah Fry:Exactly. So, every number I'm going to say here, you have to basically cut it to 30 % of the number because, as you say, 70 % of the Earth's surface is ocean. Even our agriculture, which is way, way way way way bigger than than uh the urban infrastructure is only 37 percent of earth's land mass managed forests about 10 but wilderness dominates i mean if you think about the sahara desert or uh you know the arctic the antarctic it's 52 percent of the of the land mass so if you go through and you make some assumptions about you know i think you can you can assume that in an urban landscape 100 of the land you can't you know you're not going to find a single patch where people haven't stepped on it which decreases as you go further down so in agriculture some bits of agriculture maybe it's going to be 80 percent some bits maybe slightly less more like 20 percent but in the wilderness I mean almost none of it has been stepped on by humans so when you kind of go through and calculate this it's about 15 percent of the earth's surface have ever seen a human footprint, which as you say, that's of land.

31:05Hannah Fry:And then when you consider that that's only a third of the surface because of the oceans, 5 % of the earth's total surface has ever had a human footprint on it. Isn't that amazing? That's amazing.

31:18Michael Stevens:Yeah. Because it's easy to get so sad about how there's no new frontiers. There There are no far off distant lands that we've never visited. I was thinking about that today. You're coming from Marrakesh. Just 200 years ago, I would have read about it in a book, but I would never even probably correspond with any one from there. Now it's like, oh, we're both going to be talking live from Los Angeles and Marrakesh simultaneously piece of cake. Now, are you factoring in like the actual surface area of a footstep? Because I could walk in a field, but I haven't walked on the entire field, but I've been near and seen a lot.

31:57Hannah Fry:I was cheating slightly. I did some rule of thumbs. So I said that if it's a field, then it's about 80%. 80 % of that would have been covered. Interesting. Okay. I mean, basically, I'm guessing, Michael, at this point. You get down deep enough, you're always guessing everything, frankly. So there's some estimation going on. But to do this for the vertical surface, which was the question, right? This, I mean, if we're talking about 5 % of the horizontal surface of the Earth, the vertical surface is almost nothing. So I looked it up and there's about a million established rock climbing routes around the world.

32:38Hannah Fry:I mean, I'm doing one significant figure here that is like, again, this is some serious estimation going on here. and then when you think about them i was like what do you reckon about 30 meters i mean most of them are not going to be on average about 30 meters maybe about two meters wide so once you once you run these numbers you're talking 60 square meters of climbing surface for each of these million routes i mean this is it's a rounding error we've done none of it literally none of it.

33:13Michael Stevens:Wow. We could have not climbed anything and still pretty much touched the same amount of Earth. It's so small in comparison. Wow.

33:21Hannah Fry:We think of ourselves as an invasive species. We barely got started.

33:24Michael Stevens:It really depends on what you mean by invasive, doesn't it? Because we've got satellite imagery of so much. Our emissions surround and touch so much, but yet our flesh has touched so little.

33:40Hannah Fry:Almost nothing. Yeah.

33:41Michael Stevens:And I use the word flesh just there, but usually we're wearing shoes. And when you're climbing, you'll, well, you'll have the chalk on your hands, but you know, I'm saying shoes and gloves are different too. I've always been like, no one's really touched the moon. No one's run on it barefoot yet. Does it count if you, there's fabric in between your skin and the moon surface? You're, you're counting contact we've made wearing shoes with the earth.

34:09Hannah Fry:You are absolutely right. Let's get out there and touch grass, everybody.

34:13Michael Stevens:Yeah, for real.

34:15Hannah Fry:Because you're right.

34:16Michael Stevens:You'd have to, I mean, split this by a massive fraction. This is actually a perfect segue to a question that came in from Andrew. So Andrew asked, while lying in bed, I ran my foot along my bed cover and noticed I could feel the fluffiness of it through my sock, but I could also feel my sock. It made me think about all the times I was able to discern a texture through my socks or my socks and my shoes. How am I able to feel and discern all these separate textures? I know exactly what you're talking about, Andrew, because I got, I really tripped out when I was at Derek Muller's wedding in Portugal.

34:56Hannah Fry:This is Veritasium.

34:58Michael Stevens:Veritasium. Got married and I was there. I was very honored to be there. And I was walking around the streets of Lisbon and the stones there that line the streets are very smooth, but sometimes they weren't. And I could tell the texture, like the micro texture of the stones through my socks and shoes. I don't know if this, if anyone else has experienced this, but I could like immediately tell, wow, these stones are different, but they looked identical and I'd reach down and feel them. I'd be like, oh, these aren't polished as smooth, But I couldn't tell with gross motor movements, whether it was slippy or not, it wasn't obvious, it was something different.

35:39Michael Stevens:And I think it might have been even like the vibrations, like the micro vibrations. And that reminded me of a study I saw that looked into how we measure how heavy things are, and that it's not as simple as we hold it. And we just look at how much our, our, our muscles are having to work. We really do feel like thousands of little micro emotions. We're sensitive to them when we reach out and grab something before we even lift it that tell us how easy it's going to be to change this thing's velocity. How easy it's going to be to accelerate, to pick up. And we can tell that before we even hold it.

36:16Michael Stevens:And as I dove deeper into this, Andrew, I found that there's all kinds of ways to trick your sense of weight. you can actually make things vibrate so that they feel heavier. If you take a little device and you have it vibrate side to side, not even up and down, but side to side, people will think it's heavier than it really is because it's, well, we don't know why. One hypothesis is that it's using more muscles and the brain goes, oh, it's taking a lot more muscle activity to hold this. It must be heavier, even though of course it isn't. we know for certain that you can have something vibrate up and down, especially asymmetrically, like a bigger vibration down, down.

36:57Michael Stevens:It has to be pretty fast. Like 30 hertz, I think is like the real sweet spot for making something feel heavier because of its vibrations. And so basically, we, I think, learn through experience how to tell the textures of things through other things. You can poke an object with a stick and learn if it's rough or smooth, even if you're blindfolded. And I think we learn that through time. And it's very trippy to think that it's an extension of our body, really. We learn how to feel through sticks and walking sticks and socks and shoes and gloves as though they were part of our bodies with sensory receptors on them.

37:44Michael Stevens:Though, of course, they're not. They're inert. And our bodies don't have to be this big. They can be large.

37:49Hannah Fry:You do hear that about blind people in particular, where the stick essentially becomes an extension of their body, exactly as you describe. But in a way, I mean, it's the same story in the sense that your brain is receiving signals. It's receiving some data, some input. And it's interpreting. It's making an interpretation based on. I mean, I sort of feel like almost every week we come back to this idea that like reality is not reality. It's just your brain's interpretation of it. But it sort of feels like it's the same thing.

38:24Michael Stevens:It's a little show your brain puts on for your awareness. But my glasses, right? I wear these all the time and I don't think I'm looking through glasses. This is just the world. So these have become part of my eyes as far as my brain is concerned. They're not there. They are a prosthetic that is almost all the time completely fused with my body.

38:45Hannah Fry:Or, I mean, you could say for people who don't wear glasses, this is kind of the opposite way around, that your nose is permanently in your field of vision. You just don't bother noticing it.

38:55Michael Stevens:Yeah, we ignore it. Just like you can ignore that the sock is there and go, oh, yeah, I can feel the fluffiness of my duvet through the sock. No one ever looks out at a beautiful view and says, oh, let me describe this for you. So first of all, there's this like nose down here and there's like the bar of my glasses. So imagine that's going over the top, you know, second, fifth. No, no, no. They just described the view. We can ignore these things. I feel like the classic painters, they really missed a trick, you know?

39:28Hannah Fry:I think it would have been so much more beautiful if you saw the Mona Lisa and you just had Da Vinci's nose in the middle of the canvas. Right there.

39:35Michael Stevens:Yeah. Yeah, he erased himself. He did. You know, let's embrace that. Let's put in the like weird overgrown eyelashes that are kind of down there and the little dust on the glasses that you keep ignoring or the floaters. For those of you who don't use, I mean, I see floaters too, but you know, even without glasses, you've still got artifacts in your vision.

39:57Hannah Fry:Maybe I'll stop into the Louvre on the way home, on the way home from Marrakesh and just break in at midnight, paint Da Vinci's nose on top of the...

40:05Michael Stevens:Thank you. I'd appreciate that. I'm sure there's some famous works of art in Morocco that would be easier for you to vandalize. Do you know what? That's true.

40:11Hannah Fry:That's also true. I'm also obsessed with Moroccan tiles, by the way. Expect to see me do a video on that for the internet very shortly.

40:20Michael Stevens:I can't wait to see you talk about that. So anyway, I'm glad that we get to touch you guys all through your ears every single week. Send us in your questions. Like I said, the rest is science at goalhanger.com.

40:32Hannah Fry:Or you can sign up for our free newsletter, therestis.com forward slash science. And we will see you next week. See you then.

41:02Michael Stevens:and build organizations that grow the good in the world through discipline, leadership, strong judgment, and a community that expects more from business. That's how Notre Dame graduates launch impactful careers at top companies across industries. Lead with purpose. Lead with a Notre Dame MBA. Tap now to learn more.