The Rest Is Science - How Big Is A Piece Of Chocolate?

Episode Date: February 19, 2026

At what exact chemical ratio does our beloved chocolate devolve into a mere structure of fats and sugars? How far can you dilute chocolate before its fundamental identity vanishes? And what could a comically tiny novelty stool possibly reveal about Michael Stevens? Unlike a block of pure iron or a vial of chlorine, chocolate is not one single substance but a complex and heterogeneous mixture we all take for granted. Hannah and Michael explore the chemistry and nutritional boundaries of this everyday treat. Where does the stool come in? You'll have to listen to find out. ------------------- For more information about Cancer Research UK, their research, breakthroughs and how you can support them, visit ⁠⁠https://cancerresearchuk.org/restisscience⁠⁠ 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 Video & Social: Bex Tyrrell Assistant Producer: Imee Marriott Senior Producer: Lauren Armstrong-Carter Head Of Digital: Samuel Oakley Exec Producer: Neil Fear Learn more about your ad choices. Visit podcastchoices.com/adchoices

Every Olympic dream starts somewhere. At first, it's just potential. But over time, with the right support and a few breakthroughs, it becomes something more. Make RBC Training Ground your breakthrough moment. Start your journey to Team Canada today at rbc trainingground.ca. Amazon presents Laura versus fruit flies. Swarming your fruit and terrorizing your kitchen,

these little freaks multiply at a rate that would make Grab it, say yo. Chill. But Laura shopped on Amazon and saved on cleaning spray, countertop wipes, and fly traps. Hey, fruit flies. Your baby boom ends here. Save the Everyday with Amazon. Hello and welcome to The Rest is Science.

Today, we're on an adventure. That's right, this is Field Notes, a expedition diary where Han and I trade exciting ideas and objects and discoveries, or big questions. that have been occupying our minds. Exactly. It's an expedition of the brain, as it were. You are welcome to join us. Every week we're going to bring something to show one another. It's sort of like the rest of science version of show and tell.

Now, later on, I'm going to be showing you a menagerie of things, a constellation of things, including the first book I ever wrote. And there's even more surprises than just that. This episode is brought to you by Cancer Research. So when most people think of naked mole rats, their unusual relationship to cancer probably isn't the first thing that comes to mind. But maybe it should be because it is incredibly rare for them to develop cancer, which could be partly down to their unique immune system, or it might be the way that their cells respond to damage. So scientists are studying their biology for its cancer-fighting secrets. It's a reminder that discoveries can sometimes come from places you don't expect. Cancer Research UK is the world's largest charitable funder of cancer research. Thousands of scientists of doctors and nurses work across more than 20 countries

to help turn discoveries in the lab into new tests, new treatments and new innovations. And the impact is clear. Over the past 50 years, the charity's pioneering work has helped double cancer survival in the UK, meaning more people living longer, better lives free from the fear of cancer. For more information about Cancer Research UK, their research, their breakthroughs and how you can support them, visitcancerchuk.org forward slash rest is science. As we always do, we're going to start with your questions, including this one that came in from Megan. My friends and I have been arguing for a good hour about whether space has a smell. They think since it's a vacuum, it can't.

I can't imagine they're not being one. What do you think? okay Megan, for starters, you've got what sounds like great friends. If I could meet people who would engage in that kind of debate with me for an hour, I think I would be happy forever. And the reality is you're sort of both right. You're sort of both right because in deep space where it's a true vacuum, then agreed there is no smell. However, at the same time, every Ashtonaut who has been to space, has been out on a spacewalk on the ISS, reports that there is a very distinctive odour that they get when they come back inside,

when they're in the, you know, after they've done a spacewalk, their suits and the airlock, they fill with this very unmistakable odour, the smell of space, as it were. And they describe it as like burnt steak, hot metal, gumpowder, Chris Hadfield, who's the Canadian astronaut, he said it's like a very mythical. metallic smell. NASA Ashinaught Don put it. He's got a slightly more poetic where putting it, he said, is metallic a rather pleasant, sweet metallic sensation? It reminded me of my college summers where I laboured for many hours with an arc welding torch, heavy equipment for a small logging outfit. That's the

smell, right? But the thing is, no one's completely sure about exactly where that smell comes from. And essentially there's two theories. One of them is this idea that the dying stars are filling the universe with these polycyclic aromatic hydrocarbons, the PAHs is what they're known. And these are like these high energy particles kicked off by dying stars. And they essentially just float around the universe forever. Adhere to space cross surfaces, which is why you can smell them. And the thing is, is that these molecules, you do find them on Earth. You find them in soot, in car exhaust and in charred food.

So essentially, when you're smelling a hamburger, you are effectively smelling the same compounds that drift around between the stars. But a slightly more accepted theory as to where this particular smell comes from. This kind of goes back actually to the episode that we did about cosmic rays. because you have all of these charged particles that are floating around, or even atoms that have been stripped to their electrons because of really harsh UV radiation, like single atoms of oxygen without any electrons floating around them. So the idea is that when astronauts go back into the airlock,

when the cavern is repressurized with a sort of more breathable air, these oxygen atoms then combine with the new oxygen to create ozone, And that very quick chemical reaction is the thing that makes that sort of acrid, metallic, smoky smell. That's just the boring bit in between all the interesting stuff. That's just space. But there's, I mean, there's other bits of the universe where we know what it smells like too, right? Well, yeah, using spectroscopy, we can use light to tell what molecules and atoms are in something very far away. And, I mean, we used this, first of all, to figure out what the sun was made of.

The basic point is that it was a really important moment when people were studying spectral lines from elements like hydrogen. And they could tell, oh, wow, look at this. You know, we're getting, I don't know how it all works. But they then pointed their device at the sun. And they saw the same lines that they saw from hydrogen. and they were like, wait a second, I think the sun is made of hydrogen. And that was a huge moment

because there was no way anyone could have known that. No one looked at the sun and was like, I bet that's hydrogen, you know? Like, what is the sun? It could be a whole new material. Is it burning wood? Is it a god? And these guys are like, I think it's hydrogen

because it's interacting with our instruments in the same way that hydrogen does. Because there's no way that you would, you know, at this point, if you've sort of isolated hydrogen on Earth and it's this invisible gaseous form, there's no way that you would look at this burning orb in the sky and think that the two things were the same. Well, you wouldn't. You wouldn't. Because it couldn't burn for a long time if it was burning hydrogen, right? Right. At the time, they had no concept of nuclear fusion.

So the idea that I don't actually know if that they had. time because I don't know when they did this. But my neighbors, they use spectroscopy to detect how much methane is in the Earth's atmosphere. And so they're really into it, right? They're always talking

about like, oh, hey, you know, my son and I just, you know, did some spectroscopy on some stars. And I'm like, all right, nerds. But they sound like they'd be good friends with Megan, though, to be fair. You know, I think we're going to start a little club. We should start a club.

That's right. That's right. And a spectros... What do you call the instrument that you do is spectroscopy with? Spectrometer. Spectroscope. It's embarrassing that I don't remember a spectroscope because we put a spectroscope in like the very first curiosity box. And it was one that you built yourself.

We should bring that back. Because at the time, I didn't fully know how to use it or how cool it was. But look, this is just a long way. of saying that using spectroscopy, we have been able to detect compounds in distant nebolas that we have here on Earth that have

known odors. Right. So this is astronomers were looking at the dust cloud Sagittarius B2. Basically, it's the center of the Milky Way. This is like a giant dust cloud. And they have found in their vast amounts

of of ethyl formate. Ethylformate, which smells like raspberries. It's what gives actual raspberries their characteristic smell. Right. Not just raspberries, though, also rum, which means essentially the scent of the Milky Way. Smells like a raspberry dacery. Well, I made a video many years ago where I bought a special little jar that was the smell of outer space. And it contained ethelformate and other odorous compounds that we have found in distant nebula.

And you could open it and smell it and get the smell of space. And I bought two of them. I opened and smelled one of them on camera. And the second one, I still have not opened. Because once you open it, it rapidly, you rapidly lose it. And so, I don't know, one of these days, maybe I'll let my daughter smell space. And then never again. And then never again.

The thing is, I mean, you can use this same trick. You can sort of point it at all different, you know, different parts of space. And it tells you a lot about what you expect to find there. There's actually like a quite controversial story about the smell of a particular area of space and specifically a part of Venus, because they detected this spectral signature exactly as you're describing. This is in 2020 that looked exactly like phosphine. Now, phosphine is actually incredibly difficult to make on Earth, right? So it's not particularly stable.

You essentially need a biological creature to make it. And in particular, where you find it is in penguin poop. So the fact that they found this on Venus and not down at the ground level, but up in sort of 30 miles up in the cloud decks, this kind of goldiloxone at altitude, loads and loads of this phosphine that we only really, you know, only sort of really comes from penguin poop. It did start all of these questions about like, well, maybe, maybe there are these like the Venetian sky penguins.

As it turns out, there's like now this current argument about the actual quantities of phosphine that is in that atmosphere. But, I mean, this is really genuinely how we find out a lot about the universe is by like working out what atoms there are, working out in far. what it smells like. And then drawing conclusions about what could have caused those smells in the first place. Yeah. I mean, Venus is a stinky place, right?

Down at the bottom, it's sulfur, so rotten eggs. And then up at the top, it's like sulfuric acid. That's the sort of top note. And then the accent is rotting fish and penguin poop. Which is amazing. I mean, yeah, space doesn't have one smell. It's got so many ways to titillate our senses. And you just need to know where to stick your nose.

Yeah, I'll stick it in the Raspberry Dacquay place, thank you very much. Okay, here's a question for you, Michael. This is from Justin Corrigan. Where do even and odd numbers come from? Who said one was odd and two was even and not the other way around? Was it on purpose or happy accident that even has an even number of letters and odd has an odd number? Oh, wow. Okay, there's like two questions there.

One is about sort of, I guess the etymology of even and odd. And then the next one is about a funny property of words. So, I mean, the most I know about even an odd is that I think this is kind of cool. We don't exactly know where the word odd comes from, but it could be very old Norse where odd was used to describe a point, like a place or a sharp point. And that means that maybe the word odd comes from a triangle. When you have two things, you've got, okay, you've got a pair. But then the third comes along and forms a triangle, which has a point. And then from there, they started saying, you got one person, they can do what they want.

Two people are going to have to talk to each other. But then you bring in a third, and now the voting is different. You can't have an even split. And that third person forms a triangle. We already have the word odd for that. And so odd came to mean anything that had a point that could not be divided into two soft, blunt, equal groups. I like that. That's one possibility.

This is all kind of unknown, but it makes sense, you know. And then as for the coincidence that the word odd has an odd number of letters and even has an even number of letters, that's just a wonderful example of an autological word, a word that describes itself. For example, the word, word, is in fact a word. But the word monosyllabic is not monosyllabic. If a word doesn't describe itself, it's considered heterological. Henry Segeman has a fantastic website where he's listed all these autological words,

some of which he thinks are reasonably clearly autological. Others are debatable or dodgy. These are wonderful. Like the word pronounceable is pronounceable. The word pentosyllabic is pentasyllabic. The word old, spelled O-L-D-E, is old. Hey. He sounds like he's got a great life.

I've decided, you know, we were asked that dinner party question a while ago. I'm changing my answers. I want Megan and this guy who's right. This is out of that website. Another example of a heterological word would be something like the word long, long, L-O-N-G. That's not very long. The word hyphenated is not hyphenated. So it's not autological.

But the word unhyphenated is unhyphenated. Okay. Now, this might sound like a funny little fact about words, but it brings us to the Grelling Nelson paradox. So the Grelling Nelson paradox. takes these definitions, autological, a word that describes itself, and heterological, a word that does not describe itself, and it asks,

is the word heterological, heterological, right? And so if we say that the word heterological does not describe itself, that means it's heterological. But, wait, now it does describe itself. And if we instead say that it does not describe itself, then that means that it is not heterological,

but we already had to assume that it was. Oh, this is the word version of this statement is false, isn't it? Exactly. Exactly. If heterological is heterological, like if that is true, then that means that it does not describe itself. But a word that doesn't describe itself is heterological, so it must be. If, however, we say heterological is not heterological.

So that means that it does describe itself, then that means that it is heterological. So you can never win. The only way to make this work is to say that a word is heterological if it does not describe itself and is not the word heterological. Oh, the classic rattle exclusion. Exactly, exactly. Some Rosalian exclusions save the day.

Yeah, just, you know, once again, get down deep enough, it's all gaffer tape. I love this question. This one came from Christian David Bohr. How many times can you fold a piece of chewing gum? Okay, so I actually had a good think about this, right? Because, I mean, everyone's heard the whole idea about a piece of paper. You can only only fold it seven times. And by the way, that is broadly true. And that is broadly true. And that limit exists because of tensile strength. So every time you fold it, that outside edge, it has to stretch and the inside edge has to compress and eventually either the outer fibles will snap, starts to tear, or the inner fibers become too dense, they can't bend. The thing about gum, right, which is a bit cheating, is that it's effectively a type of fluid, right? It's like a visco elastic fluid. So when you're folding it, you're not

really folding. It's more like you're needing it. It's more like you're dealing with dough, which I appreciate isn't that satisfying an answer because the answer then is effectively an unlimited number of times until it starts to degrade or dry out effectively. But if you could instead, let's assume for a moment that take that dough analogy and if instead you found some way

to sort of fold it and keep the layers from merging into each other, like using flour, for example, could you make yourself a chewing gum croissant, right? That's basically what I want to know, right? I want to do pastry chef with chewing gum. So that's what I want to do. And I think that you could then, you could, but here is where a limit occurs. Because what you could do, you know, the way that pastry chef's work is they take the pastry, they roll it out, they fold it, they turn it round, they roll it out, they fold it, they turn it round and so on and so on and so on. And what you're doing is, every time that you fold it is you're doubling the number of layers, right? You're kind of restretching it out so that you can continue to fold. After you've done one fold, you've got two layers, fine. After you've done 10 folds, you've got 1,024 layers.

Once you've done 24 folds, you've got 16 million layers, right? And once you've done 30 layers, at that point, each of the layers in your chewing gum Quasson would be thinner than the width of a single molecule. So we know it's less than 30. That's, that's, that's, that's, that's, that's, that's, that's, that's, that's, that's, that's, that's, that's, interested in eating a chewing gum croissant, Michael? Well, yeah, of course. Apparently when they make actual quassons, they only go for like, you know, 64 layers, maybe 128 layers, nothing really in comparison. Yeah, sure, but I mean, they're using, you know, bigger dough and they're also using dough and butter, but we're talking about chewing gum and saliva.

Sure. Which sounds a little better. Less French, should we say. Less French, I think, is the correct way to describe a chewing gum croissant. Okay, here's a question for you. We're staying on the food food food. Ben asks, I need to know, how small a piece of chocolate can I have? Chocolate is comprised of coca, sugar, cocoa butter, sometimes milk, emulsifiers.

But what really makes it chocolate and not a coca bee? is that it is a mixture of many things. Mixtures cannot be divisible down to the same scale as a chunk of pure iron or a file of chlorine. Each atom has the same properties. Chocolate is different from this. Goodness me, Ben, you really have gone to town on this.

It's a mixture of larger molecules. At what point can you slice chocolate and it is no longer chocolate, but it's components. Does that mean there is a lower bound to the size of chocolate? I think maybe I've spent too many days in a row subbing down voiceover scripts,

but I feel like I could have summarized that in a single sentence. Yes, but you didn't because we respect your words, listeners. Okay? Send me a question that's like literally an audiobook and Hannah will read it

and it will be our longest podcast episode ever. But I think Ben is asking a really interesting question. What's the smallest a piece of chocolate can be? And so obviously we think, okay, let me buy a chocolate bar and I can cut it into smaller and smaller pieces and it's always chocolate. Except chocolate isn't an element. It's not like I can eventually get down to an atom of chocolate where if I divide it any further, it's no longer chocolate.

That's true of something like gold. If I have one gold atom and I split it in half, I no longer have a gold atom. because a gold atom is defined as an atom with a very specific number of protons and that's it. But with chocolate, what is the smallest piece of chocolate? What form does chocolate come in at its atomic,

meaning smallest indivisible scale? There isn't one because chocolate is a mixture and chocolate contains, you know, it's not just like, oh, well, there's a chocolate molecule and a sugar molecule and a milk molecule. There is no such thing as a chocolate molecule. Chocolate, as we know it, contains hundreds of different types of molecules, different chemicals that are all, you know, originally organically put in there by the plant in the cacao bean. And these include all kinds of compounds that affect our nervous system and have their own flavors and textures and all these things.

So anyway, estimates, I've looked into this, the estimates of how many different kinds of. chemicals are in chocolate is between about 300 and 800. What? There's a lot. Wait, hang on. When you say chemicals, are you talking, you're talking about different atoms and different molecules, stable molecules? That's right.

Different stable molecules and atoms as well. If you want to dive into this, it's actually overwhelming. I feel like every few months, scientists announced the discovery of a new compound in chocolate that had been there all along, but there's like trace amounts. of it and we know that it's an analog for a neurotransmitter and that's why everyone loves chocolate or and that's why dogs are killed by chocolate. You know, there's, there's so much, it's so complicated. It is not elemental.

It's got, um, all kinds of fats and acids and all these different types of chemicals in it. It is an organic, complex material. And when chocolate is made, we roast the cacao beans and then there's this whole chocolate making process that separates the meltable cocoa butter. from the bean. And you're left with the cocoa butter, and then what doesn't melt is called the cocoa solids. And the cocoa solids are then mixed back in with cocoa butter in very specific ratios, as well as some milk, some sugar, and that's how you make chocolate as we know it.

You can also just sell people cocoa butter, right? It's a great skin moisturizer, all kinds of uses. You can use it in cooking. And you can also sell people cocoa solids by themselves. And that's what we call cocoa powder. I don't know if that's what you call it in the UK. We do, yeah, but it's very, it's very bitter. It's very, very bitter.

Now, if you add sugar to cocoa powder, you haven't made chocolate. You've made sweetened cocoa powder. You need to put some of the cocoa butter back in to make chocolate. However, that's kind of like an opinion, right? You could say cocoa powder is chocolate. You could say that the cacao bean on its own is already kind of chocolate. No, not for me. Not for me, Michael.

It doesn't count as chocolate unless it is a square of cabri's dairy milk. And yes, I would like them as a sponsor for this podcast. Continue. Perfect, perfect. Because I think that you're getting at a fundamental issue we have to get across to answer this question. And Ben, see how hard we're working for you. I think that we need to define chocolate as something that pretty much everyone will agree is chocolate. In that case, I think we need to set this upper bound and say you're going to need at least these all 800 of these molecules that are in chocolate as we buy it in the store.

And the most famous of those is probably theobroming. That is the like, it's what makes chocolate really characteristically chocolate. I think it might be what's toxic to dogs. But anyway, as a rough calculation, I looked at some of the most famous. molecules in chocolate and how large they are, and then multiply that by 800. Okay, to just kind of be like, look, if it's got 800 different molecules and some are larger and some are smaller than these ones that I'm looking at, then maybe we can get ourselves to an actual volume.

So the problem is it's really hard to know what volume of certain molecules have. You can take the molar volume of a chemical like theobroman, very famous chemical. and chocolate, and you can divide it by Avogadro's number. But that doesn't give you the volume, the size of an individual theobromine molecule. That gives you the amount of space that molecule occupies in the crystal structure of pure theobrome. But then I found that chemists also have calculated the cross-sectional diameter of molecules for collision calculations. And for a typical molecule in chocolate, it's about 130 angstroms across. So let's say 130 angstroms cubically is the volume of a typical molecule in chocolate.

What's an angstrom? Great question. It's a tenth of a nanometer. So we're talking about really small things here. But we've got 800 of them in order to represent every molecule that we believe is in chocolate. Problem. That's only one of each. Chocolate is chocolate and tastes like chocolate because of the ratios they have to each other.

So factoring that in and then assuming that maybe it's going to take another order of magnitude to make everyone happy that like this is analogous to real chocolate, we find ourselves with this answer. The smallest piece of chocolate that I believe everyone would agree, yes, that's chocolate, would be a zepto leader. I don't even know what that is. 10 to the minus what? 10 to the minus 21 liters. Whoa. That is very small. Could you see it?

You could not see it. Could you taste it? No. A zepto liter is sub-microscopic. It's down around the size of just like a very, very large molecule. It's smaller than any kind of nano thing we can imagine, little nanobot. Wait, is it too small to have color? I think it's going to be much too small to have color, yes.

But we're not quite at the answer that I want to give as my final answer, because this is just the smallest collection of molecules that will have the appropriate ratio and makeup as chocolate. Could you taste it? No, it is too small. The threshold for human taste requires like hundreds of billions of molecules. So I think we're talking more. about something to the order of 10 to the negative 13 cubic meters.

Basically, an extremely coarse grain of silt. Right. Almost sand, but not quite. Okay. You could dissolve that in some water and people could drink it and say, yeah, there's something in here and I think it might be chocolate. But any smaller than that, and you just will not be able to detect anything's in your mouth. I have a question about the molecules that you include.

A controversial question. Did you include butyric acid? Yes. I'm including all of these things. Okay, wait, wait, wait, wait, wait, wait. This is not chocolate. Is butyric acid the thing that makes American chocolate bad? Yes, it is.

Okay. Thank you for preempting. So this is, it's this acid that you find it in American chocolate. Hershey's in particular. Maybe we'll bleak that out in case Hershey wants to sponsor. But you also find it in rancid butter, in parmesan cheese and human vomit. So, but there is a reason why it's in American chocolate. There is a reason.

So this is early 1900s. And Hershey wants to mass produce chocolate. But the problem is they were adding milk. The Swiss had this really fancy pants, expensive way of drying the milk so that it didn't spoil before it went into the chocolate. So the chocolate didn't go off really quickly. So Hershey's like, okay, I'm going to develop this process. And a byproduct of the process to stop the milk from spoiling was butyric acids that went in it.

I buy into your answer. You've clearly spent a lot of time doing these calculations. And I buy into your answer on the condition that butyric acid is excluded, please. Okay, fine. Let's not allow butyric acid. That doesn't dramatically affect the volume of this very tiny thing. I want to put this into like a few other terms. like a very fine grain of sand, a very coarse grain of silt is on like the microgram,

a single or maybe two micrograms of matter. You could taste it. And if we threw in the butyric acid so that it tasted like American chocolate and made us feel like we had just puked in our mouths, it would still be a microgram. Okay? That's, you wouldn't need to add much to give it the same ratio as Hershey's chocolate or something. That's why I want an experimental version of this.

episode where you stare in one grain of salt or into some water, taste it, and they go, I know exactly what it needs. Throw in a couple of months. You throw in a billion atoms of butyric acid, which by the way is a tiny microscopic amount. And then go, taste like childhood. Taste like my childhood. But I think that, gosh, butyric acid might not even really come through in a small amount, because I'm looking this up, its flavor threshold is between,

1 and 15 milligrams per liter. Okay. So it takes a lot of it for us to taste. A lot of human vomit. That would mean that if you cut up a Hershey's bar small enough, you would be left with some flavor compounds that were above the threshold, but the butyric acid would no longer be there. So eating that one tiny piece, just that one piece,

it would once again taste like regular nice chocolate. Maybe that's the secret. If you're ever stuck with only a little, American chocolate to eat, just cut it up really, really, really small. Yes, sub-microscopic scale, you're good to go. I think we may have ruined our chances for sponsorship with Hershey's, but now all the same. Shall we go to a break? Yeah.

This segment is brought to you by Cancer Research UK. When we think about scientific breakthroughs, we usually don't think about naked mole rats, unless you listen to this podcast a lot, in which case, we've got some more stuff for you. We also think about things like cutting-edge. technology and huge amounts of data. But, you know, often progress starts somewhere quieter with just curiosity. Absolutely. And that brings us to a story of discovery in cancer that begins with two very unlikely places, a brewery and the sea. Yeast, sea urchins, and research that would later be recognized with a Nobel Prize. So today, we're asking, how does curiosity-led

science end up changing how we understand and treat cancer. Okay, well, some of the most important advances that happen in cancer research don't actually begin with cancer at all. They begin with scientists who are following an unexpected question. Yeast and sea urchins do not seem like obvious places to start if you want to understand cancer. But scientists use organisms like them because they're simple and they're fast and they're easy to observe, which makes fundamental biological processes much.

clearer. Now, the crucial insight is that the core machinery controlling how cells behave is shared across much of life. Some of the most important proteins were established very early on. They are fundamental to life, and around half of yeast genes can be directly swapped with human ones. Now, Cancer Research UK backs this kind of foundational, curiosity-led research, including work that can take many years to reveal its value, because understanding the basics is often essential to understanding disease. Okay, well, let's give you an example. An example about cancer research UK scientist, Sir Paul Nurse and Cell Division. Now, before becoming a cancer research UK scientist, Sir Paul Nurse, he worked in a Guinness Brewery where he was working with

yeast and he started getting curious about the way that these yeast cells would grow and divide. And then years later, he was working as this young researcher and he noticed something really unusual. There were these yeast cells that kept on getting longer and longer and longer, but weren't dividing. And as a result of that, his curiosity led him to identify this gene that was acting as a control switch for cell division, later called CDC2. And then scientists together, they methodically tested human genes one by one by one eventually, showing that this human version of the same gene could stand in for the yeast version. And that demonstrated that the same division control system operates in yeast all the way through to humans. And that makes it

this vital insight for cancer biology, where of course it's all about cells dividing when they shouldn't. Yeah. The circle of life. We are all bound together. Speaking of circles, let's talk about cycles. Because at the same time, Cancer Research UK scientist Sir Tim Hunt, was studying sea urchin embryos. And he was intrigued by this really bizarre fact that unfertilized sea urchin eggs can be triggered to start dividing on their own. And that offers a powerful way to study

the earliest steps of cell division. So, okay, first of all, to understand sea urchin eggs required a lot of sea urchin eggs, which was not easy for him to get in landlocked Cambridge, but he observed proteins that build up and then trigger cell division and then actively break down straight away. And these rise and fall proteins became known as cyclines because their levels cycle in time with cell division.

Also, Tim Hunt loves cycling. Bicycling. Bicycling. Anyway, all of this revealed that cell division isn't just switched on or off. It's a tightly timed and carefully regulated thing, like a metronome or a traffic light. And so together with the yeast, work, it showed that cell division follows an ordered sequence, not a random process.

Right. So you're building up this picture of how cells actually divide. And, I mean, these discoveries that they helped scientists to understand, particularly when cell division control systems fail, which is one of the defining features of cancer. And then that understanding laid the groundwork for targeted treatments. And so today, I mean, this has had a gigantic impact. It's already improving outcomes in really difficult to treat breast cancers. There are trials underway across lung cancer, skin cancer, bowel cancers. There's some drugs that work by jamming the machinery that drive cell division that slows down tumour growth in certain cancers.

And all of these advances, they only exist because the researchers, they followed these unexpected clues and then they tested them rigorously again and again over many years. Now, Cancer Research UK continues to support research across this full pathway by funding early discovery science long before outcomes are guaranteed and helping to translate that knowledge into new treatments. A humble yeast used for brewing beer and sea urchins in the ocean aren't where you would expect cancer research to begin, but it's exactly the kind of curiosity-led science that helps reveal how cancer really works. For more information about Cancer Research UK, their research, breakthroughs and how you can support them, visitcancerchuk.org forward slash rest is science. This episode is brought to you by Cancer Research UK. We often think of beating cancer as treatment, but imagine stopping it before it begins.

After years of work, Cancer Research UK scientists are launching a clinical trial of lung vacs, the first vaccine designed to prevent lung cancer. It builds on TracerX, the world's largest cancer evolution study, which tracked lung cancer cells over many years to uncover the disease's earliest warning signs. Lung Vax is designed to train the immune system to spot these signs early on, destroying 40 cells before cancer develops. So it's not treatment, but preventative, with the potential to stop lung cancer before it starts. The first stage of the trial starts this year, focusing on people at high. higher risk. It shows what long-term research makes possible. For more information about Cancer Research UK, their research breakthroughs and how you can support them, visit cancerresearchukuk.org

forward slash the rest is science. This episode is brought to you by FedEx. These days, the power move isn't having a big metallic credit card to drop on the check at a corporate lunch. The real power move is leveling up your business with FedEx intelligence and accessing one of the biggest data networks powered by one of the biggest delivery networks. Level up your business with FedEx, the new power move. Okay, we are back. We are refueled. We are ready for the next discovery. And Michael, over to you. What have you got for us? Over to me. I've got a few things. I'm traveling at the moment. And so I don't have, um, I've kind of had to scrape together some ideas. But look at this. Now, I won't explain why I'm traveling with this, but it is

a stool sample. Wait, no. What I'm showing is a little plastic vial that contains a tiny wooden stool, a sample of a stool, if you will, a three-fitted stool made of wood. It's about the size of, you know, half of my thumb. So it's just a stool sample. And there's a sticker on the vial, it says Prairie Dog Town stool sample. Prairie Dog Town is a little roadside attraction in Kansas, and they sell some of these goofy things like, you know, a box of bees, and you open it up and it's just like the letter B painted all over the inside of the box. All right. So I had to buy this stool sample, and I just carry it around sometimes. If someone ever is like, Michael, you got to blow my mind right now, I'm like, guess what I've got. It's a good thing to

have around. Is that why you continue to have that giant rucksack full of stuff for all the times people ask you to instantly surprise and amaze them? Well, yeah, you know, because they kind of expect it, but also I like it. I like it. I like having something kind of strange with me at all times. That reminds me of a show that never actually happened because of COVID. So like just before COVID, I did a show at UC Irvine, the University of California Irvine called Michael's Toys, where I just showed up with a

bag full of toys, and I just talked about them and passed them around. And it was so fun. And then with COVID, I tried to figure out a way to do the show virtually, but it was just not nearly as fun as being able to pass around a cube of tungsten. And the most illegal thing I own, which, by the way, I cannot find. Now, I've talked about this in a video, but I have an update on the item, not just the fact that I may have lost it, but there's something else quite strange. Do you know what I'm talking about?

Okay, well, I mean, you've mentioned, wait, how did you describe it? Just then the most illegal thing you own? It's the most illegal thing I own. Okay, I mean, you've mentioned quite a few things on the podcast over the time. You've mentioned radioactive lead. You've mentioned enriched uranium. There's, I'm pretty sure there's various stories about BB guns, etc. So, honestly, the mind boggles.

Okay, well, so I don't own any enriched uranium. as far as anyone knows. But the thing I'm talking about is a totally legal material. It's the way the material is arranged that makes it illegal. Okay, go on. But maybe it's not illegal anymore. It is a counterfeit US penny. That is pretty illegal, Michael.

I believe that they come down pretty hard. It is illegally manufactured currency, and it's a penny. So someone took some copper and some, you know, they put together the appropriate alloy to make a penny and then they made a mold or maybe they stamped it. I'm not sure how they made it. But it is identical to a regular U.S. penny. You could spend it and get a cent worth of value, a cent worth of goods without actually having earned that money. And as long as it costs you less than a cent to make it, you're winning. It costs a lot more than a cent to make.

It costs, or should I say, used to cost. The U.S. meant like four or five cents to make a penny. So making counterfeit pennies is probably not going to get anyone in trouble because you're losing money doing it. I won't say who gave it to me, but it was given to me by a magician who was a very interesting guy. And the thing that makes this counterfeit penny so special is that, You can tell its counterfeit for one tiny reason. And that reason is that the year stamped on it. Every penny in the U.S. has a year on it, the year that it was made.

The year on this penny is 2027, which hasn't happened yet. So no 2027 pennies had ever been made. The whole time I've owned this penny, it's been like a penny from the future, right? And then I thought philosophically, this is really interesting because by in the year 27, it will cease to be a joke and it will just look like

every other penny that's ever been made. It's the perfect crime. Exactly. Its novelty kind of expires and it almost becomes more criminal in 27 because

before that happens, people can tell that it's not real. But after 2027, it could be real. But here's obviously, I think a lot of listeners are probably thinking this. The new twist is that the United States meant, just a few months ago, announced that it will not make any more pennies ever again.

The joke lives on. That's right. So the last penny was made in 2025, which means my 2027 counterfeit penny will always have an impossible date on it. Its entire character has changed. Wait, I want to know, how did this magician get hold of it? it. What was the magician doing with it? Well, he was just a guy who also liked to collect curious things and had a lot of very interesting friends. And one of them was a metallurgist who made,

probably made counterfeit coins, not for the purposes of counterfeiting, meaning to pass it off as real currency, but to design special magic coins, like a quarter that's hollow or a quarter that can be folded up, you know, stuff like that. And he made this penny. And I think he said, you know what, if I'm going to make a penny, I can decide what year to stamp on it. Why don't I stamp a year far in the future? So it looks like it's from the future. That also makes it funny because it'll be even more believable in the future. But no one could have anticipated that in November of 2025, the last pennies would be made.

And so suddenly, I have an item with a whole new meaning. A perfect ending to the story. I do remember hearing about Banksy, the artist. I don't know, have you come across him? I don't know how well known he is in America. I am Banksy. Oh, okay. So very well known. Did you not know that?

Well, this is, okay, a story about you, of course. I've been trying to tell people, but they all just act like, oh, who is he? I think they enjoy that more. Yeah, the Bristolian accent is just a put on that you do where you're covering your identity. That's right. He had, there was a stunt that he was going to do where he printed a million pounds worth of fake 10 pound notes and where he replaced

instead of having the Queen's face on it so this is a few years ago he put on Princess Diana's face instead and then instead of it being Bank of England it was Banksy of England anyway the idea was that he was going to go to some sort of town square I think I'm remembering this right and throw out all of this money and let people collect it

and just in advance of this big stunt which he had planned he went to Reading Festival and with a bunch of his friends and handed out a bunch of these like fake £10 notes, which looked really good. And like, go on, go and see, it'll be quite funny. Go and see if you can spend them.

And these people went up, spent the £10 notes, nobody checked them. Nobody checked them. They went through absolutely fine. And at that point, Banksy realised that what he was about to do was so phenomenally illegal.

But somewhere out there in the world is this very small number of banksy 10-pound notes, which were exchanged and are now worth an absolute unimaginable amount of money. Jeez, I can only imagine. Yeah, but see, if it confuses people, if it tricks them into thinking it's real, then, yeah, it's counterfeit money and it's illegal. There was an artist, I don't remember the artist's name, but when I was a kid, my dad and I watched a documentary about this artist who drew on a sheet of paper a, a, a, a,

$100 bill by hand, like meticulously every little detail drawn by hand and then took it to a store and didn't try to pass it off as a real hundred, simply said to the person at the store, hey, this isn't a real $100 bill? But it looks real, doesn't it? Like, would you give me $100 worth of goods in exchange for this piece of art? And they agreed. So he bought like $100 worth of stuff with his fake $100 bill, but it was more of a barter exchange than it was fooled you. So I don't think that was nearly as illegal. But as soon as

you pretend it's currency and people start believing it is, then you've committed a crime. I made a documentary a few years ago about the passport, the British passport, and the number of different layers of security that they have embedded within them in order to prevent people from just copying what they look like. And it is phenomenal. I can't remember the exact number. but we're with the man who has designed a number of different British passports but it's something like 20 different systems some of them are very obvious

some of them are much less obvious you know every single page is unique there's like a pattern along the side there's also this extraordinary pattern if you look at it under UV light that is different for every country I mean it's absolutely incredible the amount of science

and well just considered engineering that goes into making one of these things There was a big controversy in the UK a few years ago when our passport's changed from red to blue. And the passport designer said that his favourite vintage, the best passport he's ever designed, was the last red one with a paper page. Because they've now got this sort of plastic page where your photograph is. So the one with the paper page was absolute counter-counter-fit genius. That's what he says.

But surely the plastic page makes it. even harder to counterfeit. I think that there was some quite clever things about the way that you could, the transparency of that paper page changed across the course of the grain of it. So my American passport still has all paper pages. My wife has a British passport with like a plastic page. And it doesn't feel like a book anymore. It feels like one of those novelty books that has like all kinds of little things inside of it,

like a clutz book. So I don't enjoy it as much. But I'm in sure it's a lot more steady and less likely to get all folded or ripped by mistake. Yeah. I mean, you know. Okay. Speaking of books, there's something that we teased in the beginning that I haven't gotten to yet. And in way of context, I wrote this book, I think, I don't actually know how old I was,

but it's one of those books that a kid makes by taking sheets of paper, folding them in half, and then stapling them together. Now, remember that I grew up in a small town in Kansas that was quite conservative in ways. And there was a very big debate around whether or not evolution should be taught in schools and how it should be taught. Should it be taught as what scientific consensus believes explains the diversity of animal life and life on earth? Or is it just a theory full of many problems? Because the truth is that all life on earth was created by a creator God. So I, I, was given many, many books as a kid about how evolution was a lie and that creation science

was this thing. Creation science is, of course, a pseudoscientific idea that maybe the world is only a few thousand years old, could be older, but that clearly nothing evolved in the way that Darwin said, that the world was obviously created by God. And so I summarized what I had learned in this book, Evolution, the lie. Wait, how old, do we reckon you were when you wrote this? Like, I wish there was a year on it, but I'm going to say I was probably 10 or 11. Okay, immediate things that stick out for me, right? One, look at that Eon evolution.

That is, there's design that's gone into that. There's like, and the different type of font that you've created for the word lie, the sort of bubble font of the word the. This is, look, it's typographic everybody. There's no pictures. There's no images. It's just clean. It gets in and gets out. It's very sophisticated.

I clearly, I must have had some kind of stencil tool. And that's how I created these different typefaces. I may have had a book of typefaces and then I traced each letter off of that page. But I don't think that I came up with this on my own, especially L-I-E-L-E-L-I-E-L-I-E. That does not look like something I came up with. Well, it certainly looks like something. thing adults had a heavy hand in influencing somewhere or another. Basically, it just reads like a whole list of the typical concerns people had with evolution.

They would say things like there's a difference between evolution with a capital E and evolution with a lowercase E, where lowercase E evolution is just the way things change. You know, it's the way the moths in England died off if they were white because of all the black soot that covered the trees. Predators could find them more easily and so the black ones became more pervasive. It might be kind of boring, but I'll read from chapter two, Stanley Miller's experiment. Are you familiar with this experiment? Of course.

Okay, well, we all know about Stanley Miller's. I'm reading from the book now. We all know about Stanley Miller's, quote, life from a test tube, unquote, experiment. He mixed gases and liquids thought to be on earth billions of years ago, i.e. before life. Then shot sparks at the mixture and poof, special amino acids found in living things. newspapers raved about, quote, life in a test tube. That is just the same as a man stacking two bricks on each other

and saying he made a 50-story skyscraper. First, those same acids can be found in dead bodies too. Just having the right acids doesn't make something alive. Second, the three needed acids weren't there. And third, many deadly acids have been formed in experiments like this. So as you can see, life can't just. happen. It must come from other life in a creationist's view, God. Okay, here's what I'm noticing from that. We've got, we've got the hook, right? You've got, you've got the excellent title right

in the beginning. You've got the counterintuitive way to see the world. Here's what everybody else thinks and here's how it should really be. We've got detail on scientific minutiae. And we have got what is essentially an extremely fascinating monologue. Vsauce was there. It was the early beginnings. Yeah, it was there. It was there. You know, this is a Vsau script.

You know, I no longer believe that evolution is clearly false. But I do think that, you know, belief in a supernatural creator does not exclude belief in evolution. Exactly as Darwin said. I think that that is to make religion way. too small. But you can definitely see how I was synthesizing information. And then rather than just saying, okay, cool, I decided to create, not videos, but there was no YouTube back then, but books where I taught what I had learned and put it into, you know, words and phrases that I thought would make it exciting. So I also actually grew up in a very religious household, where we would

often have Catholic priests who would come around and say mass in my mind. living room, right? It was not a big fancy house to be absolutely clear. It was a very small living room, but nonetheless, priests would come around and say mass. Anyway, there was one time in particular where there was a priest who was giving his sermon, his little homily, and he was talking about how science and religion were at war with one another and how science was seeking to destroy religion. And he was so deeply moved by the words that he was saying that he cried. And that was the first time I'd ever seen a growing man cry. And the thing is, is that while I completely understand the emotional weight behind feeling like your,

I mean, the sort of central story to your life is under attack, right? And I think that lots of religious people do feel like that about science. I agree with you. I don't, I have never thought that science proves that there is no God or that science really has anything to say about God in any way whatsoever. It can't. It can't because claims about God are specifically beyond Newton's flaming laser sword, meaning science cannot disprove it one way or the other. And if it thinks that it has, it's not science anymore. And so that means that religious claims are unfalsifiable, but it doesn't mean that they, therefore, are false. I also think that it's sort of, it's dishonest to pretend that science is the hunt for truth all of the way down. I think that inevitably, once you hit the absolute limits of our knowledge, there does come a certain leaf of faith, regardless of what camp you find yourself in, whether it's religious or scientific or both. You know, why is the speed of flight an absolute constant?

You know, what happened before the Big Bang? Or is the speed of light an absolute constant? We don't know. We are making some assumptions here. And there's evidence that it hasn't changed, but how would we know? What sort of evidence should we be looking for? And that's thinking scientifically. Yeah, absolutely.

It's important to me to give a little bit more context too, which is, first of all, when did this man cry in your home about the war between science and religion? Like, do you mind telling me approximately when? It was probably, it was probably, it was almost certainly the 90s. Okay. And my guess would be around 95-ish. That's very interesting because it's probably about the time that I was hearing a lot of this too. Obviously, science and religion have been famously at odds forever, okay?

But keep in mind that, you know, my father was a chemical engineer. You know, he definitely believed in evolution as an explanatory theory. And I remember being a very young child, single digits old, in Sunday school. And my Sunday school teacher, who was a woman who was about 180 years old, says to all of us that science and religion are not at war. Like, of course, God used evolution to bring about life and exactly the way scientists say. And it wasn't until the election of George W. Bush, which was in 2000, that suddenly everything changed. And a lot of adults in my life, not my parents, but other adults kept pushing creationist books on me. And I thought, I thought that we all agreed.

You know, the same church now had a different position that was much more culturally motivated than it was biblically or scientifically. And it really was a big shift. And I remember that my high school biology teacher, Mr. McDonald, was really controversial because he was fighting for Kansas to allow. evolution education in classrooms. And I really looked up to him for that because I didn't understand why it was so evil to see that evolution explained things. I didn't think there was a conflict. It was like whether or not, you know, we have a soul is very different than whether or not, you know, mammals came, you know, after bacteria. Or, or, and how, and how that transition happened. Yeah, I totally agree. I mean, I, I mean,

remember, I remember very well hearing the stories about America, having those discussions about evolution. I think there was a bit of a backlash here, actually. I think in around 2010, there was a real movement from a number of actually quite distinguished scientists who became really vocal, quite militant, frankly, militant atheists. And anyway, I just would like to do things a bit nicer. I just think extremism is best avoided in all directions. So maybe that's what you get with this podcast, right? That's what you get with me and Michael. We're nice, cuddly, all-inclusive.

The world is a broad church and so is science. That's right. And we are always learning because we're curious and above all, being thoughtful is what matters. So although I probably won't ever publish Evolution the Lie, it is a part of my journey. It's a part of my coming to understand this world that I was born into. Yeah. Well, thank you so much for sharing with us. Well, okay, that I think concludes our podcast expedition for today.

If you have any questions that you would like us to answer or any stories you want to tell us or objects you want to share with us, you can send them to us The Restis Science at gohanger.com. And you can join our newsletter at the rest is.com slash science. We are going to be back next Thursday with another edition of field notes. and on Tuesday with our normal episodes. That's right. Until then, stay curious, stay thoughtful.

Goodbye.