How Big Is A Piece Of Chocolate?

Summary

The Rest Is Science – "How Big Is A Piece Of Chocolate?"

Podcast: The Rest Is Science
Hosts: Professor Hannah Fry & Michael Stevens (Vsauce)
Episode Date: February 19, 2026

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Overview:

This episode embarks on a delightful journey through scientific curiosity, digging into the deceptively simple question: "How big is a piece of chocolate?" Hannah and Michael explore the science of mixtures, the finest scales of matter, chocolate chemistry, and wander off into space smells, number paradoxes, and even counterfeit coins. True to their ethos, it’s an expedition in wonder—moving from silly-sounding questions to profound insights about reality.

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Key Discussion Points & Insights

1. Does Space Have a Smell? [02:23 – 11:49]

• Listener Megan prompts a discussion about whether the vacuum of space has any odor.
• Astronaut Testimony:
  • Astronauts report a "metallic, burnt steak, hot metal, gunpowder" smell after spacewalks.
  • Chris Hadfield describes it as a "very metallic" scent; another astronaut likens it to "arc welding" ([03:24]).
• Why Does Space Smell?
  • Theory 1: Polycyclic aromatic hydrocarbons from dying stars coat astronaut suits; same molecules found in Earth soot, exhaust, and charred food ([04:00]).
  • Theory 2 (More accepted): Cosmic rays and reactive oxygen atoms create ozone when astronauts re-enter the airlock, causing the acrid, metallic odor.
• Space Smells Elsewhere:
  • Spectroscopy allows us to "smell" distant nebulae by identifying molecules that produce characteristic odors.
  • Sagittarius B2 in the Milky Way contains ethyl formate—the compound that smells like raspberries and rum. "The center of the Milky Way smells like a raspberry daiquiri!" ([09:10] Fry).
  • Venus, by spectral analysis, contains sulfides (rotten eggs), sulfuric acid, and possibly phosphine (which is also found in penguin poop!), sparking speculation about life ([09:52]–[11:40]).

Memorable Quote:

• Hannah Fry ([09:17]): "Essentially, the center of the Milky Way smells like a raspberry daiquiri."

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2. Why Is ‘Even’ Even and ‘Odd’ Odd? Wordplay and Paradox [11:49 – 16:32]

• Listener Justin asks about the origins of the words "odd" and "even" and their self-descriptive lengths.
• Etymology:
  • "Odd" possibly from Old Norse, describing a pointed thing (like a triangle formed by 3 after a pair).
  • "Even" is just symmetrical, divisible.
• Self-Descriptive (Autological) Words:
  • "Odd" has three letters (odd), "even" has four (even).
  • Words are "autological" if they describe themselves (e.g., "word" is a word, "monosyllabic" is not monosyllabic).
• The Grelling–Nelson Paradox:
  • Is "heterological" (word that does not describe itself) heterological?
  • Fry recognizes: This is the word version of "this statement is false" ([15:44]).

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3. How Many Times Can You Fold Chewing Gum? [16:40 – 19:44]

• Listener Christian wonders if the "seven folds" rule for paper applies to gum.
• Short Answer: No hard limit; chewing gum is viscoelastic, more kneadable than foldable.
• Pastry Chef Analogy:
  • Folding with layers (like croissants): 1 fold = 2 layers, 10 folds = 1,024, 24 = 16 million, 30 = thinner than a molecule.
  • Chewing gum could (in theory) be folded up to about 30 times before the layers become molecularly thin.
• Unexpected culinary vision: "Could you make a chewing gum croissant?" ([18:13] Fry).

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4. How Big Is the Smallest Piece of Chocolate? [19:44 – 31:42]

• Listener Ben asks: At what point does a piece of chocolate stop being chocolate and become just its components?
• Key Concepts:
  • Chocolate is a mixture, not an element—no single "chocolate atom."
  • Contains 300–800+ stable molecules (e.g., theobromine, various fats, acids, sugars, etc.).
  • For a chunk to be recognizably “chocolate,” it needs the full range of these molecules, in proper ratios.

Calculating the Limit:

• Michael estimates the smallest "true" piece of chocolate is a zeptoliter (10⁻²¹ liters) ([27:17] Fry: "I don't even know what that is. 10 to the minus what?").
  • Far too small to see or taste.
  • Humans require many billions of molecules to taste anything. So, the practical threshold is about the size of a coarse grain of silt (10⁻¹³ m³), or a microgram.
• Butyric Acid (& the American Chocolate Debate):
  • Hannah objects to including butyric acid—the compound associated with "off" flavors in US chocolate (and also found in rancid butter, parmesan, human vomit).
  • The conversation pivots on defining “real” chocolate based on regional taste ([29:01]–[30:55]).
• Experimental Suggestion:
  • Fry: "I want an experimental version where you stir in one grain of salt into some water, taste it, and then go, I know exactly what it needs—throw in a couple more...” ([30:42]).
• If you cut a Hershey bar down to a microgram, the off-flavors would vanish—but it would still be chocolate chemically.

Notable Quotes:

• Michael Stevens ([27:25]): "The smallest piece of chocolate that I believe everyone would agree, yes, that's chocolate, would be a zeptoliter."
• Hannah Fry ([29:01]): "Is butyric acid the thing that makes American chocolate bad?"

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5. Tales of Counterfeit Coins and Currency Security [39:43 – 50:57]

• Michael shares his "most illegal" possession: a counterfeit US penny dated 2027 ([42:41–45:23]), which will now forever be anachronistic since the US Mint has ceased penny production.
• Fun with wordplay: "Stool sample" as a literal small model stool.
• Hannah relates Banksy’s fake £10 notes—now rare collectibles ([46:47]).
• The science of passports: Hannah describes UK security features, including transparent paper and unique UV patterns ([49:06–50:20]).

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6. Childhood Books, Science, Religion, and Growing Up Curious [50:59 – 61:30]

• Michael confides he once wrote a home-made book called “Evolution the Lie” at age 10 or 11, reflecting the influence of creationist culture in 1990s Kansas ([52:22–56:05]).
• The hosts share thoughtful, personal tales about growing up in religious households, the science-religion tension, and how curiosity and open-mindedness shaped their approaches.

Notable Quotes:

• Michael Stevens ([56:05]): "This is a Vsauce script... I no longer believe evolution is clearly false... but you can see how I was synthesizing information and trying to teach."
• Hannah Fry ([57:35]): "I think... once you hit the absolute limits of our knowledge, there does come a certain leap of faith, regardless of what camp you find yourself in, whether religious or scientific or both."
• Stevens ([58:19]): "Claims about God are specifically beyond Newton’s flaming laser sword; science cannot disprove it one way or the other—and if it thinks it has, it’s not science anymore."

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Notable/Memorable Moments & Quotes

• On the Grelling–Nelson Paradox:

  • Fry ([15:44]): “Oh, this is the word version of ‘this statement is false,’ isn’t it?”
  • Stevens ([16:27]): “Exactly. Some Russelian exclusion saves the day.”

• On Hershey Chocolate:

  • Fry ([29:01]): "Is butyric acid the thing that makes American chocolate bad?"
  • Stevens ([30:55]): "Throw in a billion atoms of butyric acid, which, by the way, is a tiny, microscopic amount, and then go, 'Tastes like childhood.'"

• On Science vs. Religion:

  • Fry ([57:35]): "...there does come a certain leap of faith, regardless of what camp you find yourself in..."
  • Stevens ([58:19]): “Science cannot disprove it one way or the other—and if it thinks it has, it’s not science anymore.”

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Timestamps of Important Segments

• [02:23 – 11:49] Smells in space, spectroscopy, and cosmic chemistry
• [11:49 – 16:32] Even/odd numbers, wordplay, paradoxes
• [16:40 – 19:44] Chewing gum folding and molecular logic
• [19:44 – 31:42] The smallest possible piece of chocolate (main segment)
• [39:43 – 50:57] Counterfeit coins, Banksy, and science of passports
• [50:59 – 61:30] Childhood, belief, and the relationship between science and religion

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Tone and Style

Warm, playful, and encouraging of curiosity, the episode showcases the unique blend of Vsauce’s scientific enthusiasm and Hannah Fry’s witty skepticism. Listeners are welcomed as equals, and the hardest questions are treated as fuel for a shared intellectual adventure.

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Summary

From cosmic aromas and the paradox of language to the fundamental nature of chocolate, this episode is a joyous romp across scientific thinking. Michael and Hannah employ humor and personal storytelling to render abstract ideas tangible—with detours into culinary science, chemistry, and the philosophy of knowledge itself. Whether pondering why chocolate can’t be atomically defined, or how cultural forces shaped their curiosity, the hosts never lose sight of the fun and mystery at the heart of science.

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Endorsed summary for both chocolate lovers and science fans!

Transcript

[Hannah Fry]

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[Hannah Fry]

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[Michael Stevens]

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 Hannah and I trade exciting ideas and objects and discoveries or big questions that have been occupying our minds.

[Hannah Fry]

Exactly. It's a. 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.

[Michael Stevens]

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 it's. It's. There's even more surprises than just that.

[Hannah Fry]

This episode is brought to you by Cancer Research uk.

[Michael Stevens]

So when most people think of naked mole rats, their unusual relationship to cancer probably isn't the first thing that comes to mind.

[Hannah Fry]

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.

[Michael Stevens]

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.

[Hannah Fry]

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.

[Michael Stevens]

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.

[Hannah Fry]

For more information about Cancer Research uk, their research, their breakthroughs, and how you can support them, visit cancerresearchuk.org restiscience as

[Michael Stevens]

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 there not being one. What do you think?

[Hannah Fry]

Mm. 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'd be happy forever. And the reality is you're sort of both right. Sort of both right. Because in deep space where it's a, you know, a true vacuum, then, agreed, there is, there is no smell. However, at the same time, every astronaut who has been to space, who's been out on a SPACewalk, on the ISS, reports that there is a very distinctive odor that they, 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 odor. The smell of space, as it were. And they describe it as like burnt steak, hot metal, gunpowder. Chris Hadfield, who's the Canadian astronaut, he said it's like a very metallic smell. NASA astronaut Don put it, he's, he's got a slightly more poetic way of putting it. He said it's metallic, a rather pleasant, sweet, metallic sensation. It reminded me of my college summers where I labored for many hours with an arc welding torch, heavy equipment for a small logging outfit. That's, that's the smell.

[Michael Stevens]

Right.

[Hannah Fry]

But the thing is, no one's completely sure about exactly where that smell comes from. And there's essentially, there's two, 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 spacecraft surfaces, which is why you can, you can smell them. And the thing 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 our, the episode that we did about cosmic rays because you have all of these, these, these charged particles that are floating around, or even atoms that have been stripped of their electrons because of really harsh UV radiation, like, like single atoms of oxygen without any electrons floating around them. So the idea is that when astronauts go back into the airlock, when, when the cavern is with 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. Of the universe that. Where we know what it smells like too, right?

[Michael Stevens]

Well, yeah. Using spectroscopy, we can use light to tell what molecules and atoms are in something very far away. And, I mean, we. We use 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. We're. 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. 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.

[Hannah Fry]

Because there's no way that you would. You would. You know, at this point, if you sort of isolated hydrogen on earth and it's this. 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. You just wouldn't.

[Michael Stevens]

Well, you wouldn't. You wouldn't. Because it couldn't burn for. For a long time if it was burning hydrogen. Right.

[Hannah Fry]

Right.

[Michael Stevens]

At the time, they had no concept of nuclear fusion. So the idea that. I don't actually know if at the time, because I don't know when they did this, but my neighbors, they. 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

[Hannah Fry]

they sound like they'd be good friends with Megan, though, to be fair. You know, I think they could start up a little club.

[Michael Stevens]

We should start a club. That's right. That's right. And a spectro. What do you call the instrument that you do? Spectroscopy with spectrometer. Spectroscope. It's embarrassing that I don't remember 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 nebulas that we have here on Earth that are. That have known odors, right?

[Hannah Fry]

So this is astronomers. We're looking at the dust cloud sagittarius B2. Basically, it's the center of the Milky Way, right? This is like giant dust cloud. And they have found in there vast amounts of. Of ethyl formate.

[Michael Stevens]

Ethyl formate, which smells like raspberries. It's what gives actual raspberries their characteristic smell, Right?

[Hannah Fry]

Not just raspberries, though, also rum, which means essentially the center of the Milky Way smells like a raspberry daiquiri.

[Michael Stevens]

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 ethyl formate 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. The second one I still have not opened because once you open 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.

[Hannah Fry]

And then never again. Thing is, I mean, you use that. You can use the same trick. You can. 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. There's actually like a quite controversial story about the smell of a particular area of space and, 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. 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. This kind of Goldilocks zone at altitude, loads and loads of this phosphate 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's in the 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 in part 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.

[Michael Stevens]

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.

[Hannah Fry]

Yeah, I'll stick it in the raspberry daiquiri, please. Thank you very much. Okay, here's a question for you, Michael. This is from Justin Corri. 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?

[Michael Stevens]

Oh, wow. Okay. There's like, two questions there. One is about sort of, I. I guess the etymology of even and odd, and then the next one is about a funny property of words like. So, I mean, the most I know about even and 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. 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. 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. 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 Segamon has a fantastic website where he's like, listed all these otological 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 pentasyllabic is pentasyllabic. The word old, spelled O l, D, e is old.

[Hannah Fry]

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 to set up that website.

[Michael Stevens]

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 like fact about words, but it brings us to the Grellin 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.

[Hannah Fry]

Oh, this is the word version of this statement is false, isn't it?

[Michael Stevens]

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 to say the that a word is heterological if it does not describe itself and is not the word heterological.

[Hannah Fry]

Oh, the classic Russell exclusion.

[Michael Stevens]

Exactly. Exactly. Some Rassalian exclus illusions save the day.

[Hannah Fry]

Yeah, just, you know, once again, get down deep enough. It's all gaffer tape, Michael. That's what we've discussed.

[Michael Stevens]

I love this question. This one came from Christian David Bohr, how many times can you fold a piece of chewing gum?

[Hannah Fry]

Okay, so I, I actually, I had a good think about this, right, Because, I mean, everyone's heard the, the whole idea about piece of paper, you can only. Only fold it seven times. And by the way, that is, that is broadly true. 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 fibers 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 viscoelastic fluid. So when you're folding it, you're not really folding. It's more like you're kneading it. It's more like you're, you're. You're dealing with dough, which isn't that, Which I appreciate. Isn't that satisfying an answer, because the answer then is effectively an infinite, an unlimited number of times until it, 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, like using flour, for example, could you make yourself a chewing gum croissant? Right, that's, that's, 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, but here is where a limit occurs, because what you could do, you know, the way that pastry chefs work is they, they take the pastry, they roll it out, they fold it, they turn it around, they roll it out, they fold it, they turn it around, and so on and so on and so on. And what you're doing every time that you fold it is you're doubling the number of layers, right? You're kind of re. Stretching 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 10, 24 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 croissant 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 the hard upper limit. Interested in eating a chewing gum croissant, Michael?

[Michael Stevens]

Well, yeah, of course.

[Hannah Fry]

Apparently when they make actual croissants, they only go for, like, you know, 64 layers, maybe 128 layers. Nothing really in comparison.

[Michael Stevens]

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.

[Hannah Fry]

Sure.

[Michael Stevens]

Which sounds a little better. Less French, should we say less French, I think is the correct way to describe a chewing gum croissant.

[Hannah Fry]

Okay, here's a question for you. We're staying on the food B. Ben asks, I need to know how small a piece of chocolate can I have? Chocolate is comprised of cocoa sugar, cocoa butter, sometimes milk emulsifiers. But what really makes it chocolate and not a cocoa bean 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 vial 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 its 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.

[Michael Stevens]

Yes, but you didn't, because we respect your words, listeners. Okay, send me a question that's like a. 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?

[Hannah Fry]

And.

[Michael Stevens]

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 like, 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.

[Hannah Fry]

Hang on. When you say chemicals, are you talking. You're talking about different atoms and different molecules. Stable molecules.

[Michael Stevens]

That's right. Different stable molecules and atoms as well. It's. If you want to dive into this, it's actually overwhelming because I feel like every few months scientists announce 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 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.

[Hannah Fry]

We do, yeah. But it's very. It's very bitter.

[Michael Stevens]

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.

[Hannah Fry]

No, not for me. Not for me. Michael, it doesn't count as chocolate unless it is a square of Cadbury's dairy milk. And yes, I would like them as a sponsor for this podcast. Continue.

[Michael Stevens]

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 theobromine. 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 multiplied 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 certain molecules have. You can take the, the, the molar volume of a chemical like theobromine, very famous chemical in 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 theobromine. But then I found that chemists also have calculated the, like, cross sectional diameter of molecules for collision calculations. And for a typical molecule in chocolate, it's about 130angstroms across. So let's say 130angstroms 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. Yeah, 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.

[Hannah Fry]

Yeah.

[Michael Stevens]

We find ourselves with this answer. The smallest piece of chocolate that I believe everyone would agree, yes, that's chocolate, would be a zeptoliter.

[Hannah Fry]

I don't even know what that is. 10 to the minus. What?

[Michael Stevens]

10 to the minus. 21 liters.

[Hannah Fry]

Whoa.

[Michael Stevens]

That is very small.

[Hannah Fry]

Could you see it?

[Michael Stevens]

You could not see it?

[Hannah Fry]

Could you taste it? No.

[Michael Stevens]

A zeptoliter is sub microscopic. It's down around the size of just like a very large molecule. It's smaller than any kind of nano thing we can imagine. Little nanobots.

[Hannah Fry]

Wait, is it too small to have color?

[Michael Stevens]

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. Okay. All almost sand, but not quite.

[Hannah Fry]

Okay.

[Michael Stevens]

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.

[Hannah Fry]

I have a question about the molecules that you included. A controversial question. Did you. Did you include butyric acid?

[Michael Stevens]

Yes, I'm including all of these things.

[Hannah Fry]

Okay, wait, wait, wait, wait, wait, wait, wait. This is. This is not chocolate.

[Michael Stevens]

Is butyric acid the thing that makes American chocolate bad?

[Hannah Fry]

Yes, it is. Okay, thank you for preempting. So this is. It's. It's this acid that you find. You find it in American chocolate. Hershey's in particular. Maybe we'll bleep that out in case Hershey's wants to sponsor us. But you also find it in rancid butter, in parmesan cheese and human vomit. So. And there. 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 acid 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.

[Michael Stevens]

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 2 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.

[Hannah Fry]

That's why I want. I want an experimental version of this episode where you stir in one grain of salt into some water, taste it, and they go, I know exactly what it needs. Throw in a couple of months.

[Michael Stevens]

Throw in. You throw in a billion atoms of butyric acid, which, by the way, is a tiny, microscopic amount, and then go, tastes like childhood.

[Hannah Fry]

Tastes like my childhood.

[Michael Stevens]

But I think. 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. You would. 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.

[Hannah Fry]

Maybe that's a secret. If you're ever stuck with only American chocolate to eat, just cut it up. Really, really, really, really small.

[Michael Stevens]

Yes. Sub microscopic scale, you're good to go.

[Hannah Fry]

I think we may have ruined our chances for sponsorship with Hershey's, but now all the same. Shall we go to a break?

[Michael Stevens]

Yeah.

[Hannah Fry]

This segment is brought to you by Cancer Research uk.

[Michael Stevens]

Now, 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.

[Hannah Fry]

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.

[Michael Stevens]

So today we're asking, how does curiosity led science end up changing how we understand and treat cancer?

[Hannah Fry]

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.

[Michael Stevens]

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.

[Hannah Fry]

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 cur 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 gen 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 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.

[Michael Stevens]

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 cyclins 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.

[Hannah Fry]

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 with. There are trials underway across lung cancer, skin cancer, bowel cancers. There's some drugs that work by jamming the machinery that drives cell division, that slows down tumour growth in certain cancers. And all of these advances, they only exist because the researchers, they followed these, 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.

[Michael Stevens]

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.

[Hannah Fry]

For more information about Cancer Research uk, their research breakthroughs and how you can support them, visit cancerresearchuk.org restive science.

[Michael Stevens]

This episode is brought to you by Cancer Research uk.

[Hannah Fry]

Radiotherapy is over a century old, but it is still changing. Cancer Research UK helped lay the foundations of radiotherapy in the early 20th century and has driven progress ever since.

[Michael Stevens]

Radiotherapy remains one of the cornerstones of cancer treatment today. Every year, millions of people worldwide benefit from Cancer Research UK's work. To make it more precise, scientists are

[Hannah Fry]

still refining how radiotherapy is delivered. And one example is an experimental treatment called flash radiotherapy, which delivers radiation in fractions of a second, up to a thousand times faster than standard radiotherapy and

[Michael Stevens]

early studies suggest that speed could make a real difference. Flash radiotherapy may cause up to 50% less damage to healthy cells, but scientists

[Hannah Fry]

don't yet know why healthy cells seem to be spared. So Cancer Research UK are working to answer that, understanding it could be key to reducing side effects in the future.

[Michael Stevens]

For more information about Cancer Research uk, their research and breakthroughs, and how you can support them, visit cancerresearchuk.org thereest ISS the world moves fast. Your workday even faster. Pitching products, drafting reports, analyzing data. Microsoft 365 Copilot is your AI assistant for work built into Word, Excel, PowerPoint and other Microsoft 365 apps you use, helping you quickly write, analyze, create and summarize so you can cut through cluster and clear a path to your best work. Learn [e-mail] M365 copilot.

[Hannah Fry]

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?

[Michael Stevens]

Over to me. I've got a few things I'm traveling at the moment and so I don't have. 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.

[Hannah Fry]

Wait, no.

[Michael Stevens]

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 legged 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 and sometimes if someone ever is like Michael, you gotta blow my mind right now. I'm like, guess what I've got. It's a good thing to have around.

[Hannah Fry]

Is that why you continually have that giant rucksack full of stuff for all the times people ask you to instantly surprise and amaze them?

[Michael Stevens]

Well, yeah, you know, cause 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. 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?

[Hannah Fry]

Okay, well, I mean, you've mentioned. Wait, how did you describe it just then? The most illegal thing you own.

[Michael Stevens]

It's the most illegal thing I own.

[Hannah Fry]

Okay. I mean, you've mentioned quite a few things on the podcast over time. You've mentioned radioactive lead. You've mentioned enriched uranium. There's. I'm pretty sure there's. There's. There's various stories about BB guns, et cetera. So I honestly, the. The mind. The mind boggles.

[Michael Stevens]

Okay, well, so I don't own any enriched uranium as far as anyone knows. But the thing. The thing I'm talking about is, is a totally legal material. It's the way the material is arranged that makes it illegal.

[Hannah Fry]

Okay, go on.

[Michael Stevens]

But maybe it's not illegal anymore. It is a counterfeit US Penny.

[Hannah Fry]

That is pretty illegal, Michael. I believe that the. They come down. They come down pretty hard.

[Michael Stevens]

It is illegally manufactured currency, and it's a penny. So someone took some copper and some, you know, they put together the. 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 US Penny. You could spend it and get a cent worth of value, a cent worth of goods, without actually having earned that money.

[Hannah Fry]

And as long as it costs you less than a cent to make it, you're winning.

[Michael Stevens]

It costs a lot more than a cent to make. It costs, or should I say used to cost the US Mint like 4 or 5 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, the thing that makes this counterfeit penny so special is that you can tell it's counterfeit for one Tiny reason. And that reason is that the year stamped on it. Every penny in the US 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 2027, it will cease to be a joke and it will just look like every other penny that's ever been made.

[Hannah Fry]

It's the perfect crime.

[Michael Stevens]

Exactly. Its novelty kind of expires, and it almost becomes more criminal in 2027, because before that happens, people can tell that it's not real. But after 2027, it could be real. But here's obviously, and I think a lot of listeners are probably thinking this, the new twist is that the United States Mint just a few months ago announced that it will not make any more pennies ever again.

[Hannah Fry]

The joke lives on.

[Michael Stevens]

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.

[Hannah Fry]

Wait, I want to know. How did this magician get hold of it? What was the magician doing with it?

[Michael Stevens]

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. Of counterfeiting, meaning to pass it off as real currency, but to. 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 gonna 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

[Hannah Fry]

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.

[Michael Stevens]

I am Banksy.

[Hannah Fry]

Oh, okay. So very well known.

[Michael Stevens]

Did you not know that?

[Hannah Fry]

Well, this is. Okay. A story about you, of course.

[Michael Stevens]

I've been trying to tell people, but they all just act like, oh, who is he? I think they enjoy that more.

[Hannah Fry]

Yeah, the Bristolian accent is just a put on that you, that you do when you're covering your identity.

[Michael Stevens]

That's right.

[Hannah Fry]

He had, there was a stunt that he was going to do where he printed a million pounds worth of fake ten pound notes and where he replaced, instead of having the Queen's face on it, 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 pound notes which looked really good. And we're like, go on, go and see, it'll be quite funny. Go and go and see if you can spend them. And these people went up, spent the ten pound notes. Nobody checked them, nobody checked them. They went through absolutely fine. And at that point Banksy realized 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.

[Michael Stevens]

Geez, I can only imagine. Yeah, but see, if, if, if it confuses people, if it tricks them into thinking it's real, then yeah, it's counterfeit money and it's, 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 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, the person at the store, hey, this isn't a real hundred dollar bill. But it looks real, doesn't it? Like, would you give me a hundred dollars worth of goods in exchange for this piece of art? And they agreed. So he bought like a hundred dollars worth of stuff with his fake hundred dollar 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.

[Hannah Fry]

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 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 passports changed from. From red to blue. And the passport designer said that his favorite 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 last, the one with the paper page was absolute counter. Counterfeit genius. That's what he said.

[Michael Stevens]

But surely the plastic page makes it even harder to counterfeit.

[Hannah Fry]

I think that there were some quite clever things about the way that you could. The transparency of that paper page changed across the course. Really across the. The grain of it. Yeah.

[Michael Stevens]

So my. 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. Like one of those novelty books that has, like, all kinds of little things inside of it, like a klutz book. So I don't enjoy it as much, but I'm sure it's a lot more steady and less likely to get all folded or ripped by mistake.

[Hannah Fry]

Yeah, I mean, you know.

[Michael Stevens]

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. 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 many 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 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.

[Hannah Fry]

Wait, how old do we reckon you were when you wrote this?

[Michael Stevens]

Like, I wish there was a year on it, but I'm gonna say I was probably 10 or 11.

[Hannah Fry]

Okay. Immediate things that stick out for me. Right. One look at that eon. Evolution. That is. There's. 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.

[Michael Stevens]

The.

[Hannah Fry]

This is. Look, it's typographic, everybody. There's no. There's no pictures. There's no images. It's just clean. It gets in and gets out.

[Michael Stevens]

It's very. 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. 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. Lie, Lie. That does not look like something I came up with.

[Hannah Fry]

Well, it certainly looks like something adults had a heavy hand in influencing somewhere or another.

[Michael Stevens]

Basically, it just reads like a whole list of the two. 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. 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 prevalent. It might be kind of boring, but I'll read. I'll read. From chapter two. Stanley Miller's experiment. Are you familiar with this experiment?

[Guest or Interviewee]

Of course.

[Michael Stevens]

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 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.

[Hannah Fry]

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 a. An extremely fascinating monologue. Vsauce was there. It was the early beginnings.

[Michael Stevens]

It was. Yeah, it was there. It was there. You know, this is a Vsauce script, you know. No, I no longer believe that evolution is clearly false, but I do think that, you know, belief in, 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.

[Hannah Fry]

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 living room. It was not a. It's 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. 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 grown man cry. And the thing is, is that while I completely understand the emotional weight behind feeling like you're. I mean, the, 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.

[Michael Stevens]

It. 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, that means that religious claims are, you know, unfalsifiable, but it doesn't mean that they therefore are false.

[Hannah Fry]

I also think that it's, 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, or scientific or both. You know, why is the speed of light an absolute constant? You know, what happened before the big bang?

[Michael Stevens]

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, it hasn't changed. But how would we know what sort of evidence should we be looking for? And that's thinking scientifically.

[Hannah Fry]

Yeah, absolutely.

[Michael Stevens]

It's important to me to give it 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?

[Hannah Fry]

Probably it was? Probably. It was almost certainly the 90s.

[Michael Stevens]

Okay.

[Hannah Fry]

And my guess would be around 95ish.

[Michael Stevens]

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 in 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, what's 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 mammals came, you know, after bacteria or, Or. And how. And how that transition happened.

[Hannah Fry]

Yeah, I totally agree. I. I mean, I 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. 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 get. We're nice, cuddly, all inclusive. The world is a broad church and so is science.

[Michael Stevens]

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.

[Hannah Fry]

Yeah. Well, thank you so much for sharing it 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, us, you can send them to us. There is scienceolehanger.com and you can join

[Michael Stevens]

our newsletter at thereestis.com science we are

[Hannah Fry]

going to be back next Thursday with another edition of Field Notes and on Tuesday with our normal episodes.

[Michael Stevens]

That's right. Until then, stay curious, stay thoughtful. Goodbye, Troy. The Odyssey, the Iliad, all of these great ancient epics depict a monumental collapse that destroyed the interconnected empires of 3,000 years ago. And to understand the Bronze Age apocalypse that homer wrote about 400 years after it happened, subscribe to Empire World History, a fellow gold hanger podcast where we are deep diving into the biggest imperial collapse in ancient history. To get a flavor of the series. Here is a clip from our episode with none other than Stephen Fry.

[Stephen Fry]

It is one of my favorite subjects. The story of the Greeks and the siege of Troy and Odysseus return home. Of course, I say Greeks. Homer called them the Achaeans, the Danaans, the Argives. The word Greeks is a much later one, but it refers really to the Mycenaeans, a warrior aristocracy essentially obsessed with honor and reputation that would give them an eternal glory. A kleos, as they call it. It's the kleos that's in the name of so many Greeks. You know, Cleopatra and all, the Socrates, Heracles, who's Hercules, you know, Hera's glory. He was actually named Heracles because she hated him, because he was a love child of Zeus. And she never liked Zeus's love childs, her husband, her errant husband. And so, as an attempt to placate her, Teiresias, because he was born in Thebes, suggested that he change his name as a baby. This was, to Heracles, the glory of Hera.

[Hannah Fry]

It didn't help much.

[Stephen Fry]

It didn't help at all. Athena even put her on Hera's breast when Hera was asleep because it would bond them if he suckled her milk. But she woke and saw it and tossed him away, and her breast milk spread across the sky to form the Milky Way.

[Hannah Fry]

I didn't know that story because Galaxy,

[Stephen Fry]

of course, is from the Greek for milk, galactic, as in lactic. So the chocolate makers are right. Anyway, this is completely separate.

[Hannah Fry]

Lovely, though.

[Michael Stevens]

Keep going.

[Guest or Interviewee]

Don't stop.

[Hannah Fry]

Well, we really hope you enjoyed that clip. To hear more on the Bronze Age apocalypse and how it shaped the ancient Greek epics, just subscribe to Empire, wherever you get your podcasts.

[Michael Stevens]

Anthony Scaramucci here. As much as I love talking politics and let's be honest, it sometimes gets me in trouble, my other and probably safer passion is books. We just dropped our 200th episode on my podcast, Open Book, Another goal hanger show. And to celebrate, we spoke with none other than Waterstones and Barnes and Noble CEO James Dawn. Let's take a listen. It's a phenomenal piece of technology, James. Everything has changed. Our phones have changed, our computer, way

[Hannah Fry]

we look at the TV.

[Michael Stevens]

The book is a 500-year-old piece of technology. You think in 500 years it'll be with us, James?

[Guest or Interviewee]

I think so. And I think it's astonishing simply how extraordinarily durable it is and effective it is. And as you say, newspapers, we don't read them anymore. It's on your iPad, it's on your phone. Music. The format changes all the time. Not with books. And I think when publishers also concentrate on the physical attributes of a book as well, they are lovely things and treasures forever.

[Michael Stevens]

There may be too many books being published right at this moment. Do you believe that and tell us why?

[Guest or Interviewee]

Far, far too many books. And it's getting ever, ever worse. This is speaking as a bookseller who crafts a physical space space. So I only have so much space and there's more and more and lots of self publishing. Nothing wrong with writing a book and wanting to see it out in the world. But for myself, I have to curate all the time. And the bit that I regret is that people get upset with me for not carrying their book. Well, I just can't. I don't have the space for it. And that's really what I mean. The fact that they sell on Kindle or they sell on Nook or online is fine by me. I want people reading, but I myself have to curate. And the reality is that I can't take the vast majority of books that are published.

[Michael Stevens]

I hope you enjoyed that clip. To hear more from James dawn and others, subscribe to Open Book with Anthony Scaramucci. Wherever you get your podcasts.