Science Friday - Did the fire at the Library of Alexandria set humanity back?

Episode Date: September 15, 2026

In 48 B.C.E., a massive fire ripped through the Library of Alexandria in Egypt, one of the largest and most significant ancient libraries. An estimated 100,000 works of literature were lost. Throughout history, there are lots of examples of things being “lost”: cities, like Pompeii, graves of figures like Genghis Khan, and works of art from masters like Leonardo di Vinci.Author Sam Kean explores these historical losses in his new book, “The Museum of Lost Things.” He joins Host Ira Flatow to discuss what we can learn from them.Read an excerpt from “The Museum of Lost Things: True Tales of Fabled Treasures, Legendary Cities, and Mythical Creatures That Vanished From History”Guest:Sam Kean is the author of eight books, including “The Museum of Lost Things." He is based in Washington, D.C.Transcript will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Follow our show on Instagram, TikTok, Facebook, and Bluesky @scifri and sign up for our newsletters. Got a science question that’s keeping you up at night? Call us: 877-472-4374 Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Hey, it's Ira, and you're listening to Science Friday. In 48 BC, a massive fire ripped through the Library of Alexandria, one of the largest and most significant ancient libraries. It's estimated around 100,000 works of literature were lost, a staggering number. It's hard not to get a little sad at the scale of the great works that no longer exist. Well, throughout history, you know, there are lots of examples of things being lost. You've got lost. like Pompeii, lost graves of figures like Genghis Khan, lost works of art from masters like

Da Vinci. And with each loss is a little bit of hope that someday, somehow, they'll be found again. My next guest has been on a quest to document the parts of history that have been lost, so we can remember them once more. Sam Keane, author of The Museum of Lost Things, welcome to Science Friday. Hello, thanks for having me. Nice to have you back. All right, let's go back to 48 BC. Do we know what it would have been like to walk through the library of Alexandria? Yeah, it would have been a lot like walking through the stacks of a modern college library or something like that. I think nowadays we think about libraries as having big open spaces, you know, people sitting around tables, maybe collaborating a little bit.

These were much more compact and a lot of scrolls jammed into a small place and probably not very well organized. you kind of had to know the gatekeeper, the librarian, pretty well. You might not be able to find anything. But the amount of knowledge they had in there was probably one of the most comprehensive, if not the most comprehensive, in terms of just the percentage they had of all the known knowledge in the world at the time. So you're talking about Greek, Roman, scientists, philosophers, things like that? Yeah, and going all the way out to the Middle East, going to Persia, even a little bit from places like China. They had a really wide array they were looking for.

They wanted to make it as universal as they possibly could. And of course, so many of these items were made on papyrus, which is so fragile, right? I mean, they would have gone up in flame easily. Yes, they would have gone up very easily, yeah. And they had to copy them over and over too, which, you know, could introduce errors and things like that. And there were full-time jobs of people who just had to copy these scrolls because they would fall apart. How much of any of that actually survived? We have very, very little, just scraps of one papyrus scroll is the only thing we know that was in the original Library of Alexandria because it's a list of documents that they had at the library.

So there was no reason to have that anywhere else. Some of the things they had, you know, from the Iliad, the Odyssey, other Greek myths, Aristotle, Plato, have survived in other forms. But we only have one scrap that we know was in the library. Yet with all this talk about a fire, you raised questions in your book about whether there really ever was a fire. Yeah. Why is that? There definitely was a fire there in 48 BC when Julius Caesar was down there fighting a war. We know there was a fire around there.

But there are stray references to the library and the attached museum after that point. We don't know if they maybe rebuilt it. There was also an annex. So perhaps they had some things in the annex. and, you know, we just don't know what exactly happened to all the knowledge there. I think kind of a sadder situation would be one theory is that just over time, as the Roman Empire sort of crumbled, people just neglected the library and let these things die through just simple neglect, not copying them anymore, letting them go to waste, things like that. Yeah, no, we talked now about the Library of Alexandria, losing lots of stuff, but this actually happened at the Library of Congress. Did it not? A fire there? There have been multiple fires there, yes, over the years. They had pretty poor fire prevention practices, I will say that, for a lot of its history. And we did lose some very important things. A lot of the original documents, you know, things that Thomas Jefferson had donated, things like that, have been lost in these fires.

Is there any chance for both of these cases that somewhere some of these lost things may be recovered? It's always possible. They have found papyrus scrolls on mummies and things like that. They would use them to wrap the mummies or they might write an incantation on one side of a piece of papyrus that they didn't want to use anymore. And on the backside, there might be something interesting that they could read or find out or maybe between layers or something like that. And especially with new technologies coming out, infrared technologies, AI systems, where they are able to read even when they've been burned or written over. Sometimes you can extract the text from beneath it. So, yeah, there's always a possibility, especially with the ancient stuff, that we could find something someday. So did this loss the Library of Alexandria set us back in the human journey of knowledge?

How really important was this? I think it was pretty significant because if you look back at it, there are documents. We still have some of them, but they were building things like steam engines way back in the BCs. And if you think about that, we didn't get to that point again until something like the 1700. So that's a long, long time where technology maybe not stagnated, but it really didn't progress as fast as it might have. Had we had this knowledge and been able to spread it and had we not had the collapse at sort of a restaurant, at a lot of the development. So you can talk about that and also devices like the Antikythera mechanism, which is another

one I talk about in the book. Let's go right into that. Tell us about that. Essentially, it's the world's first computer. It was from the BCs. We don't know exactly when, but maybe first century BC or so. And it was not an electronic computer, obviously. It was mechanical.

But they used it to calculate astronomical phenomenon. So eclipses were one example. You could set a date and it would tell you what was going on in the heavens at that point. You could set it to an eclipse. It would tell you what date it was going to happen. And it's pretty amazing to think that they had these devices, essentially computers, thousands and thousands of years ago. And we didn't know about another device like this. In fact, we didn't know about another gear even that they had in ancient times until some sponge divers off the coast of an island in Greece happened to find.

this mechanism all rusted and corroded over among a shipwreck, a bunch of, among some statues and things like that. But if they had not stumbled into it, we would have no idea that they had computers back then. And it really, I think I said, that's kind of the motivation for me writing the book was how fragile a lot of this information and this knowledge is about what we know about the past and all of what we've lost. Sam, do we have any idea what it was used for? We have a general idea of what it was used for. Basically, they were trying to predict astrological phenomenon. So eclipses, where the planets would be at certain times of the years. You could cast horoscopes, things like that. And how much serendipity is involved in this? Because didn't they almost just throw that thing overboard and thought it was a piece of junk? Yeah, they were pulling up a lot of stuff from the bottom. Some of it just looked like boulders. And they said, well, that's no good. Let's toss it over. And they were about to toss it over. And they were about to toss it over.

until someone looked a little closer, saw what looked like metal, maybe some corrosion there, and they said, well, why don't we hold on to this one a little longer? And eventually, it split open. It cracked after it dried out and was just lying there in the museum when the director's cousin walked through, noticed some gears and said, we should take a closer look at this. And eventually, that's how they figured out that it was one of the most important pieces, if not the most important, that we've salvaged from ancient times. Very, very cool.

And did we know before this that ancient Greeks used computers? We had no idea. We did not know even that they had gears or anything like that. This was really, really something that we had no idea existed. And it tells you a little bit more as well because it's not like someone just sat down one day and invented this thing out of nothing. Just like someone wouldn't sit down and invent an iPhone out of nothing. There were a lot of precursors to it. That's just the way technology works.

So it tells us a lot about the development of it. And it's a little scary in some ways to think of how much we might have missed had this device not turned up. It was hand cranked, right? I mean, it had a little dial on the side and you could wheel it forward, wheel it around. If you want to picture it, essentially the front had dials. So imagine a clock face with more than three hands on it, something like seven or eight hands. One for the sun, one for Venus, Mercury, the moon. And you would turn the crank on the side and these dials would spin around.

and around the outside was essentially the zodiac signs. So you could tell where it was in the heavens in the sky at any one point in the year. But this was still at a time when we believed the galaxy, as we speak, was geocentric, that our solar system revolved around the Earth, right? A lot of people did, yeah. Actually, going back to the Library of Alexandria, there were some people there who proposed a heliocentric solar system at the time. Knowledge maybe hadn't spread all that far.

but the idea was a bit out there. With this one, though, I think it's even more remarkable that they were able to figure out all of the elaborate gearing based on a notion that was false that the Earth was the center of the solar system. It makes it even more impressive in some ways. You know, reading this book reminded me of an event that was unexplainable to me at the time.

I want to tell you about this. I was visiting the ancient ruins of Topram next to Anger Wat in Cambodia. And a tour guide knew that I was a science guy He drew me away to show me something outstanding and astounding, a picture of what certainly looked like a stegosaurus etched into the 12th century temple. I mean, is it possible? I mean, this really does look like a stegosaurus,

that there were ancient archaeologists and that knowledge was lost? Well, it was something it reminds me of. I talk in the book about the Peking Man fossils, which are probably the most famous lost fossils in history. It was a group of not just men, but men, women, and children that were discovered in China in about 1910s, 1920s. And at the time, there were locals there who called them dragon bones. And in fact, the place they found Peking Man, the bones there, was called Dragon Bone Hill. So people back then definitely knew that these were the bones of some sort of animal.

And, you know, I don't think it's implausible that they might have thought that these animals existed in the past. I don't know a lot of details about what they believed, but I know that in Western culture, at least, a lot of people for a long time believe that animals simply did not go extinct, that no species had ever gone extinct. They might have had beliefs that these animals existed at one point, and it's not implausible to me that they would have looked at or found something like a stegosaurus and, you know, put something up on a wall. Who knows exactly what they were thinking or what they thought about it. But I don't think it's implausible that they would have found these bones and decided to put something up on a wall.

You know, that brings me to the point that we think about technology as being a modern concept, perhaps we need to reframe our view on this. What do you think? Yeah, and writing this book really made me think of, again, how precious knowledge is and the fact that technologies, it's not a, we think about it kind of as a linear progression nowadays and it's building and it will always keep expanding. But there have been more expansions and contractions of not just technology, but knowledge, basic knowledge in history as well. So it's a much more circular and nonlinear process than I would have imagined before I started writing the book. So what's your big takeaway in writing this book? It really makes me cautious interpreting history

just because you have to worry about what you're not seeing. And I think archaeologists are doing a very, a better job nowadays of looking at context, you know, gathering little bits of pollen and things from the soil to help us understand what we're not seeing or what we were ignoring before. But it really does make you cautious in interpreting information. But it also makes me kind of marvel at all we've been able to hold on to because in a lot of cases, things survived wars, natural disasters, you know, the rise and fall of empires just sitting in someone's attic or, you know, tucked away somewhere. And there is a historian I talk about in the book. He said, you know, we can certainly mourn the loss of something like the Library of Alexandria,

but in some ways, that's not a great way to preserve knowledge to have a central storehouse because those are often in places of great wealth, great power, which also makes them targets for invading armies and things like that. So it's kind of putting all your eggs in one basket, that situation. Whereas if you spread the information out, it's much more likely that something will survive somewhere. And that's really borne out if you look at the historical record. Well, Sam, as somebody who loves history, I really love this book. Thank you for taking time to be with us today. Well, thanks for having me. Sam Keen is the author of the Museum of Lost Things. Check it out. This episode was produced by Kathleen Davis. And if you've got a favorite lost thing you

want to tell us about, give us a call. 8774-Sy-Fri. 877, the number four, Syfri. 8-7-7-7. We'll catch you next time. I'm Ira Flato.