June 21, 2024


Costing Accounting Everyday

Lost Women of Science Podcast, Season 2: Episode One – The Grasshopper

The first modern-style code ever executed on a computer was written in the 1940s, by a woman named Klára Dán von Neumann–or Klári to her family and friends. And the historic program she wrote was used to develop thermonuclear weapons. This season, we peer into a fascinating moment in postwar America through the prism of Klári’s work. We explore the evolution of early computers, the vital role women played in early programming, and the inextricable connection between computing and war.

To understand how Klára Dán von Neumann arrived at computer programming, we need to first understand where she came from. Born in Budapest to a wealthy Jewish family, Klári grew up surrounded by artists, playwrights, and intellectuals. Her first marriage, to an inveterate gambler, took her on a tour of Europe’s casinos, and in one of them she had a chance encounter with the famous mathematician John von Neumann.

This podcast is distributed by PRX and published in partnership with Scientific American.



Episode 1: The Grasshopper

PRESIDENT HARRY S. TRUMAN: The world will note that the first atomic bomb was dropped on Hiroshima….

KATIE HAFNER: World War II started an international arms race.

ARCHIVAL TAPE: Britain fires its first H bomb to join the United States and Russia as ranking atomic powers

KATIE HAFNER: New machines made weapons as precise and deadly as possible. 

ARCHIVAL TAPE: It’s the world’s first electronic computer.

KATIE HAFNER: But those machines couldn’t function without instructions. 

ARCHIVAL TAPE: The only requirement now is that we tell our computer what to do. This is the job of an individual called a programmer.

KATIE HAFNER: Klara Dan Von Neumann –Klari to her family and friends–helped bring one of those machines – one of those famous and infamous objects – to life. And in doing so, she became one of the world’s first computer programmers. 

I’m Katie Hafner, and this is Lost Women of Science, where we unearth stories of scientists who didn’t receive the recognition they deserved in their lifetimes.  

Our second season is all about Klara Dan von Neumann and her place in computer history.

JANET ABBATE: I’m Janet Abbate, and I’m a professor at Virginia Tech in the department of Science, Technology and Society.

KATIE HAFNER: In 1999, Janet wrote a book called Inventing the Internet.

JANET ABBATE: And while I was working on that, I kept looking for the women in the story. 

KATIE HAFNER: But she didn’t find many. 

JANET ABBATE: And I thought, well, my next book, I’m going to go find the women in computing. And I thought there weren’t going to be that many because nobody had written about them. 

KATIE HAFNER: And so, she went back to the 1940’s, the dawn of electronic computers.

JANET ABBATE: They were just so invisible I thought, well, there couldn’t have been that many and I couldn’t have been more wrong.

KATIE HAFNER: The gender landscape of the 1940’s computer scene, it turns out, was not completely male-dominated. In fact, it was actually common for women to be coders then.

And that’s one of the things Janet wrote about in her next book: Recoding Gender.

But one name was noticeably absent: Klara von Neumann.

JANET ABBATE: to be completely honest. I, I know virtually nothing about her. 

KATIE HAFNER: I’ve also been writing about computers for a really long time, more than 30 years in fact —I’ve read countless histories, and I even co-wrote one in 1996. But last year, as we were putting together our Lost Women of Science list of the overlooked and under-credited, the name Klara von Neumann caught me off guard. 

She was married to John Von Neumann, the famous Hungarian mathematician and computer pioneer–I certainly knew who that was. She worked on Monte Carlo simulations, which were first used for atomic bomb calculations but have since become a fixture of the computing landscape. Today, the Monte Carlo method is used to make sense of huge volumes of data–and do things like predict elections and model the spread of COVID-19 –I knew about Monte Carlo simulations too. Klari also wrote code for the ENIAC, an early electronic computer. Anyone who has spent a good amount of time writing about computers has heard of the ENIAC. But in the middle of all these knowns, was this new name. This new character.

JANET ABBATE: Or maybe I shouldn’t be surprised that I hadn’t really heard about Klara Von Neumann. Um, I guess that’s the point of having this season.

KATIE HAFNER: Indeed, it is the entire point of this season. And so I started digging.  

…And, it turns out, Klari’s life was hiding just out of plain sight. At the Library Congress, we stumbled upon a trove of documents that were saved alongside her husband’s –letters, legal forms, manuscripts, computer code, pay stubs, diaries. Our problem became sorting through the material, constructing a life out of thousands of pages…

And to make matters worse, at the Library of Congress…

[pages turning]

SOPHIE MCNULTY: I think this is a mix of Hungarian and English.

[pages turning]

KATIE HAFNER: I’m a little worried about all the Hungarian. We should just scan everything.

KATIE HAFNER: A ton of the material was in Hungarian…

Still, we quickly learned the broad strokes of Klari’s story:

She was from a wealthy Jewish family in Budapest. She married John von Neumann, a famous genius, and she was brought into this coding work kind of randomly. 

But who was this person, really? What can she tell us about the origins of computing? And how did she get so lost? In this season, we’re going to get to the bottom of those questions, and then some. 

For this episode, our first of the season, our goals are twofold: To paint a picture of Klari’s early years, bringing this unusual, colorful character to life. And to lay out the story of how she ended up in the United States –her entry point into a world of secrecy and computers and nuclear weapons. 

In order to understand this story ourselves, we needed to get our hands on a particular document–a manuscript that would ground us as we mapped out her life. It’s a manuscript that we knew existed because the Library of Congress had fragments of it, but we caught wind that the rest of it was somewhere else…



MARINA VON NEUMANN WHITMAN: Come on in. Oh my goodness.

KATIE HAFNER: It’s the very last.

MARINA VON NEUMANN WHITMAN: Thank you, yes, how great, thank you.

KATIE HAFNER: The last dahlias, the last statice.


KATIE HAFNER: Oh, they’re looking a little peaked, aren’t they?

MARINA VON NEUMANN WHITMAN: Well, just that one.

KATIE HAFNER: I just picked them this morning.

I’ve just arrived in Concord, Massachusetts at the home of Marina von Neumann Whitman, a prominent economist who’s now retired. She’s Klari’s step daughter. 

Klari died almost 60 years ago, but Marina is still holding onto some of her stepmother’s old papers. Our first stop: Marina’s study.

[walking noises]

KATIE HAFNER: Oh so that’s it there?


KATIE HAFNER: Wonderful.

KATIE HAFNER: I’m pointing at four files I see on a high shelf. 

KATIE HAFNER: So should I get those down for you? 

MARINA VON NEUMANN WHITMAN: No, wait a minute. I think I can do it.

KATIE HAFNER: Yeah, you’re tall. You’re tall. …

MARINA VON NEUMANN WHITMAN: Oh yeah. Well, I was taller. 


KATIE HAFNER: Marina grabs the folders…


KATIE HAFNER: …then leads the way to her dining room table.

MARINA VON NEUMANN WHITMAN: Why don’t you get a sense of what’s there?


KATIE HAFNER: The document I’m looking for is Klari’s unpublished memoir. And as promised…here it is. 

KATIE HAFNER: So it’s four folders, um, with little ties on them. And  I am opening this one folder that says “miscellaneous typescripts”, and then “drafts of following: Two New Worlds, Not So Merry Washington, the Blue Humber, the Computer and the Grasshopper.”

KATIE HAFNER: According to the table of contents, the memoir was to be divided into 8 chapters and a postscript. Marina has either full or partial drafts of 6 of them. They’re all typewritten in English, a few of them over and over again as Klari produced new drafts, editing by hand in the margins in her familiar, illegible – scrawl.

MARINA VON NEUMANN WHITMAN: The proposed title was very revealing. It was called “A Grasshopper in Very Tall Grass.” So she obviously saw herself as this little creature sort of buried in a much taller environment. I don’t think she ever realized how remarkably intelligent she was.

KATIE HAFNER: And if Klari was this grasshopper, her tall grass could have been a lot of things…From the towering mind of John von Neumann, her husband, to the skyscrapers in the US, where she was an immigrant. From the overwhelming personal tragedies she would one day experience, to the entire universe she would find herself in…surrounded by famous scientists who were building weapons that were unlike anything the world had seen.

Klari was already in her mid-thirties when she joined these scientists and started to code. By then, she’d already lived many lives. Her path to programming was serpentine and unusual. She herself, complicated and layered.

We know the result of her work, because we’re living in it. The question is, where is she in all of this? And a fundamental part of that question is: Who was Klara Dan von Neumann?

So before we get into stored-program computers and flowcharts and simulation algorithms, we need to take a step back, and meet Klari the person…this self-described “grasshopper in very tall grass.”

Klari’s story begins in 1911.

KLARA VON NEUMANN: I was born shortly before World War I in Budapest…

KATIE HAFNER: That’s one of our translators, Eva Szabo, reading from the manuscript I found at Marina’s.

KLARA VON NEUMANN: …the capital of that lighthearted, gay country best known for its gypsy music and songs…and for its hopelessly unhappy and unlucky history.

KATIE HAFNER: The Budapest of Klari Dan’s childhood was in constant flux. By the time Klari was 10, she had lived through a World War and a violent communist revolution in Hungary.

But, her life wasn’t all dark and gloomy:

GEORGE DYSON: She came from, from a very wealthy aristocratic family.

KATIE HAFNER: That’s George Dyson, a historian of technology. He wrote Turing’s Cathedral, a book about the origins of the digital universe.

GEORGE DYSON: She had been a very pampered child. A figure skating, national figure skating champion at age 14. 

KATIE HAFNER: In an early passport photo we found, she had short, curly brown hair, and big, piercing gray-brown eyes. In non-official photos, she wears glasses and she’s often smiling.

MARINA VON NEUMANN WHITMAN: And I’m told she was a great beauty.

KATIE HAFNER: That’s Marina again. George also visited Marina to read Klari’s papers. In fact, he beat me by 10 years. He was looking for any material he could find on early computers.

GEORGE DYSON: this was the first person record of all this questionable stuff, you know, what happened during the Oppenheimer hearings? What happened during the Monte Carlo. It’s all there in, you know, fountain pen. And here’s Klari who just is there, and she’s doing things, and it was just clear cut.

KATIE HAFNER: But long before Klari found herself immersed in the world of Monte Carlo simulations and people like J. Robert Oppenheimer and Albert Einstein, back when she was a young girl, her life seemed to be going in, well, not that direction.

GEORGE DYSON: She was well educated, but certainly didn’t show any interest in science or anything like that.

KATIE HAFNER: Klari was not a budding scientist, but she was getting a very idiosyncratic education, surrounded by Europe’s best and brightest. 

GEORGE DYSON: Just sort of this insanely interesting intellectual group of people, you know, you’d turn around at breakfast and there would be a playwright or an artist or a great mathematician.

KATIE HAFNER: Her extended family was large and tight-knit, and they all lived together in separate flats of an extravagant villa, which still stands to this day at the top of the Gellért hill, one of the most beautiful neighborhoods in all Budapest. And the house…

KLARA VON NEUMANN: …gradually became the center of the “Roaring Twenties” Budapest version.  

KATIE HAFNER: At Klari’s family home in Budapest, there was a constant flow of celebrated figures in and out. They would host huge parties that lasted all night.

GEORGE DYSON: It was sort of a mix between a scientific conference and a rave or something.

KATIE HAFNER: There’s a word for this kind of event, it’s like one of those untranslatable German words, except this one’s Hungarian…On the page, it looks like it’s pronounced mulatsag, but, well, here’s Eva reading from Klari:

KLARA VON NEUMANN: It is absolutely impossible to translate “mulatsag” in one simple word. It is not a party, it is not a feast, it is not even an orgy; it is simply the spontaneous combustion of a bunch of people having a good time. 

KATIE HAFNER: And Klari loved meeting these colorful characters. 

KLARA VON NEUMANN: I, a tiny little speck, an insignificant insect just chirping around to see where the most fun could be had.

KATIE HAFNER: Klari defines herself as this little speck, this grasshopper looking for fun. And, my first instinct is to fight this. Because, her letters show a complicated, deep, emotional person–not just a hedonist. And definitely not a speck.

AGI ANTAL: She had huge heart. I mean, she was so very open-hearted, so, so nice to everybody who she loved.

KATIE HAFNER: That’s Agi Antal, another Hungarian translator. She’s describing the sense she got of Klari after reading a bunch of her letters. 

AGI ANTAL:  It is a pity that she had not more self confidence. She should have had. You know how it is, the most brilliant people don’t believe how brilliant they are.

KATIE HAFNER: Klari was self-deprecating to a fault. Other people seemed bigger and more important.  Relationships drove her life. For instance, this is how she frames her memoir:

KLARA VON NEUMANN: This is a sort of autobiography about other people. 

KATIE HAFNER: Among these other people were the men she loved and married. Her marriages gave her access to other ways of living, of being. Through her marriages, she got many things – opportunity, purpose, travel. Marriage, for Klari, wasn’t just an objective, but also a vehicle–a useful one in a man’s world.

The beginnings of this lifelong search for love and fulfillment are documented in her private diary. We found it buried in a file in a box at the Library of Congress. 

The diary is rich blue and stamped with gold flowers. It’s the type of thing you want to admire before opening. Inside, is Klari’s teenage heart — 

KLARA VON NEUMANN: Three long years of struggle and pain come to an end with this page. I’ve been living in this intoxication of love for almost three weeks.

And this first love, Francis, won her over with his adventurous and impulsive nature. They got married in May of 1931, when Klari was only 19, and the relationship took Klari on something like a tour of Europe’s casinos.

KLARA VON NEUMANN: I was most frightfully in love, the grandiose flinging of the last chip on the table seemed to me the most manly and elegant gesture…until one day it dawned on me that those colored chips were just about all the money we had.

KATIE HAFNER: Even Klari, a fan of spontaneity and whimsy, was growing increasingly frustrated by her marriage. 

And this was how she was feeling one fateful night, when she arrived in Monte Carlo, Monaco’s famous gambling hotspot. 

ANANYO BHATTACHARYA: And Klara Dan is there with her first husband, who’s an inveterate gambler,

KATIE HAFNER: That’s Ananyo Bhattacharya, who’s just published a biography on John Von Neumann called The Man from the Future.

ANANYO BHATTACHARYA: and whilst he’s busy gambling away their money, she gets bored and she retires to the bar. But, just before she leaves the roulette wheel, she bumps into John von Neumann, a fellow Hungarian. And he’s, uh, a minor celebrity. A Hungarian would, uh, would know of him.

KATIE HAFNER: This was the early 30s. But, Ananyo says John von Neumann eventually became almost as well known as Albert Einstein. Some considered him even smarter. As a child, he memorized entire chapters of books. And it’s said that by eight, he had mastered calculus.

Here’s how John von Neumann’s friends described him in a 1966 documentary:

NARRATOR: While still in his twenties, von Neumann had already solved Hilbert’s fifth problem for compact groups…

PAUL HALMOS: Essentially it was his genius at synthesizing and analyzing things.

NARRATOR: Proved the mean ergodic theorem….

PAUL HALMOS:  That’s what Johnny could do and what no one else could do as well.

NARRATOR: Provided a mathematical foundation for quantum theory…

OSCAR MORGENSTERN: He would think all the time.

NARRATOR: Proved the Minimax theorem and theory of games…

OSCAR MORGENSTERN: He worked with tremendous energy and fantastic speed.

NARRATOR: And done basic work in foundations of mathematics.

ANANYO BHATTACHARYA: von Neumann was considered almost a species apart.

KATIE HAFNER: And that night in Monte Carlo, Klari found this powerful, almost mythical brain sitting at the bar. She would later recall that Johnny was quote “babyishly plump and round like a child’s drawing of the man on the moon.” He was wearing his characteristic three-piece suit–he would never be caught dead in anything else, even on hikes or horseback. 

ANANYO BHATTACHARYA:  They, they start chatting and, uh, he explains he has a system, to win, uh, roulette.

KATIE HAFNER: Of course he does. Right?

ANANYO BHATTACHARYA: yeah, it’s fail safe, fail safe, he says.  So he loses all his money.

KATIE HAFNER: That’s some system.

ANANYO BHATTACHARYA: Um, yeah, it turned out it wasn’t foolproof. So he then, uh, finds her at the bar and uh, basically says, will you buy me a drink? And she agrees. 

ANANYO BHATTACHARYA: And, uh, and they chat and they get on like a house on fire, 

KATIE HAFNER: But, this was the early 1930’s, and Klari was married and so was Johnny. So Johnny went back to his wife in the US, and Klari stayed in Europe with her husband, and life went on for a while.

But this meeting in Monte Carlo was important. 

For one thing, these two people liked each other, and they wouldn’t forget it.

And for another: Monte Carlo would reappear in a place they couldn’t have expected. In the late 1940s, Klari and Johnny would work on a computer program to execute a mathematical algorithm, and that algorithm would be named for that very gambling hotspot: It’s called the Monte Carlo method.

NIC LEWIS: the Monte Carlo method uses a statistical sample… 

KATIE HAFNER: That’s Nic Lewis, a historian of technology at Los Alamos National Laboratory.

NIC LEWIS: in order to make predictions about parts of the natural world. Say the motion of particles without having to do detailed calculations on the possible behavior of every single particle. 

KATIE HAFNER: So the Monte Carlo method imagines many possible outcomes of a particular event—like the motion of particles. And then it simulates the event over and over again, to determine the probability of each outcome.  It uses randomness to solve problems.

GEORGE DYSON: And it’s sort of a window into the way that that physics is really, is really working.

KATIE HAFNER: For example: say you’re sitting at that roulette wheel in Monte Carlo, placing your bet. The ball will land in one of 37 slots. But what would it take to derive an equation accounting for every variable? The ball’s initial position, its kinetic energy, its angular momentum – and all the other factors: the friction acting on the ball, the ricketiness of the table, the crookedness of the house.

It’s reasonably simple to state mathematically how each individual factor shapes the odds for what the ball will do in the next small fraction of a second: spin smoothly, deflect from an obstacle, or settle in a landing slot. But deriving a single equation to predict the odds for final landing positions directly from starting conditions is much, much harder. So instead, Monte Carlo uses statistics. It plays endless rounds at a simulated wheel, collects the data, and presents its findings.

Meaning, with the Monte Carlo Method, you’re living out the possible scenarios of what could happen to get a sense of what’s probable.

But, in simulating all of these scenarios, in walking down all these paths, the unlikely is eventually, inevitably realized. 

And this ability to map out not only what is probable, but also what is improbable, might be a fitting analogy for Klari’s own life.

She went down many random paths….

KLARA VON NEUMANN: It was sheer luck, and a strong tendency for rainbow-chasing, that made me a wanderer on two continents among this maze of people. 

KATIE HAFNER: …until she kind of just fell into the world of computing by way of a marriage.

THOMAS HAIGH: Klara Von Neumann, as far as we know, did not have an interest in mathematics or science or nuclear weapons. 

GEORGE DYSON: Yeah, she really was just, you know, in the right place at the right time.

KATIE HAFNER: And so although a life full of bomb calculations, coding, and famous physicists was not the most probable one for a young figure-skating champion from Hungary, it had a non-zero probability, and she–this grasshopper always looking for better horizons–sampled different outcomes, until she landed there.

NIC LEWIS: Her life was improbable, but not impossible.

KATIE HAFNER: Coming up, we’ll look at what happened after two Hungarians walked into a casino, and met at the bar. I’m Katie Hafner and this is Lost Women of Science. 


KATIE HAFNER: Klari’s chance meeting with Johnny at Monte Carlo had ripple effects that spanned an ocean. Their relationship changed the course of her life and maybe the course of early computer programming too. Soon Klari would face the second world war to occur in her lifetime. And in the aftermath take part in making deadlier warfare possible. But, in the early 1930s, this reality was still very far off. Klari was married to someone else. And so was Johnny.

And besides, he lived halfway across the world in Princeton, New Jersey. He worked first at the University there as a visiting professor, then later as mathematics professor at the Institute for Advanced Study. 

And that’s where he went after that brief encounter at the casino, returning to his work and his wife, Mariette. Their daughter, Marina (yes, the same Marina from earlier) says her mother was a “shining star.” 

MARINA VON NEUMANN WHITMAN: She liked being the center of attention and I think it annoyed her that she was so much in the background.

KATIE HAFNER: And Johnny, as Ananyo points out, wasn’t always the doting husband. 

ANANYO BHATTACHARYA: He was never very plugged into, any kind of, uh, domesticity. He was pretty clueless. 

And so, as may be expected …

ANANYO BHATTACHARYA: She rapidly gets tired of being a rather distant second in von Neumann’s list of priorities, which, you know, he’s described by his friends as being addicted to thinking. And so, um, Mariette, uh, leaves him for, um, another physicist actually. Um, and, uh, he never really understands why.

KATIE HAFNER: Johnny was heartbroken. And confused. Why would she trade a perfectly fine genius-husband, for a non-genius husband? 

And so, in 1937, in the midst of his heartache, Johnny went back to Budapest for a visit. 

ANANYO BHATTACHARYA: And he basically looks up Klara Dan. Unfortunately, Klara has remarried, uh, this time to a banker who’s 18 years older than she was.

KATIE HAFNER: While Johnny had been in Princeton, Klari had kept herself busy in Budapest. After that fateful night in Monte Carlo, Francis, Klari’s first husband, kept gambling away their money. In one extreme episode,  Klari and Francis took a road trip across the south of Europe. Francis lost all of their cash (and then some!), stranding them in northern Italy, without enough gas money to get home. When Francis continued gambling after that, they finally got divorced in 1936.  And then, a month later,  Klari promptly replaced him with his opposite: a respectable banker 18 years her senior. In her memoir, she calls him her “daddy husband.” 

KLARA VON NEUMANN: He was a kind, gentle, attentive husband…and I was bored to tears.

KATIE HAFNER: So while yes, she was married, Johnny’s return to Budapest in the summer of 1937 could not have come at a better time. 

ANANYO BHATTACHARYA:  They start talking first on the telephone and then they started meeting in cafes and they talked for hours. She said the subject of conversation veered wildly from politics to ancient history. And the differences between America and Europe. And the advantages of having a small Pekinese or a Great Dane.

KLARA VON NEUMANN: It became perfectly clear that we were just made for each other.

GEORGE DYSON: You know, they were immediately obsessed with each other. And again, she was just so magnetic and charming and, and carefree in a way. And he was the smartest guy she’d ever met.

KATIE HAFNER: But like summer camp, it had to end. Johnny went back to the U.S. and Klari stayed in Budapest, but there was no stopping things…

ANANYO BHATTACHARYA: And their exchanges continue through letters and telegrams.

KATIE HAFNER: Hundreds of these letters and telegrams are now preserved at the Library of Congress.

Klari’s own files are largely subsumed by her husband’s, and four of us spent the better part of a week there, looking for anything we could find in Klari’s tall sloping hand. 

At first glance, her elegant old Hungarian script looks like a seismic readout, the words themselves are bunched up on the page and they slant to the right, as if headed somewhere. We had trouble telling which of her many languages these were written in. Her native Hungarian? English? Or were we seeing some rare use of her German or French? She knew them all. 

Johnny’s letters also seamlessly moved from language to language – but unlike Klari’s, his have been sorted, pored over, and luckily for us, transcribed and translated. And so, a lot of what we pieced together of their relationship came from Johnny rather than Klari.

And Johnny started writing to Klari immediately after that romantic interlude in 1937.  Here’s Nandor Tary reading from one of Johnny’s letters:

JOHN VON NEUMANN:  A billion thanks for the letter.  It is lovelier than anything I could imagine, warmer than anything I ever hoped, it’s all together the sweetest thing – it’s almost like yourself.

KATIE HAFNER: These early love letters are unbelievably sweet. Still, it quickly became clear that the woman Johnny had decided to hitch his heart to was a complicated person. 

There’s one letter in particular, which I call The Long Dark Letter. It’s about ten pages. Johnny wrote it on a stopover in Milan in August of 1938…This Long Dark Letter is a stunning document, really, because it demonstrates with remarkable prescience the rocky emotional road ahead for these two people. The letter shows that Johnny cared about Klari deeply.

JOHN VON NEUMANN: is this evil world bothering you all night? The world that does not give you what you should have deserved long ago, Happiness. 

My heart breaks to think of you being worried, and restless in a long dark night.  

KATIE HAFNER: Their impassioned letters are a blizzard of emotional outpouring. They suggest a couple who were constantly reaffirming their connection. These are two people who weren’t simply infatuated – they were well matched – Johnny,  the fiery but jovial scientist with a mind in perpetual motion, and the equally fiery quick-witted, fun-loving Klari.

As for Klari’s current husband, the boring banker…

KLARA VON NEUMANN: The inevitable of course happened. 

ANANYO BHATTACHARYA: And she tells her husband that basically the, the, the, their marriage is over. And, um, he seems to take it pretty well.

KATIE HAFNER: In 1938, a few months after Klari’s 27th birthday, Klari and Johnny got married. 

ANANYO BHATTACHARYA: Klari’s divorce comes through at the end of October, they get married within two weeks and they sail back to America the next month in November.

KATIE HAFNER: Klari seemed like the sort of person well-suited to such a move. She was a well-seasoned traveler, good at adjusting to new people and places. But, when the couple finally got to Princeton, it wasn’t quite the newly wed life that Klari had imagined–even jaded as she was by her prior marriages. For one thing, Johnny was immediately hard at work at the Institute for Advanced Study leaving Klari to her own devices in this totally foreign place.

And also, this was 1938…

ANANYO BHATTACHARYA: All this time, of course a war is creeping closer.

JOHN VON NEUMANN: All these treaties of different military powers are leading to war, I believe more than ever. 

KATIE HAFNER: Germany had already annexed Austria and Hitler was poised to invade Poland. And Johnny and Klari’s Jewish families were still in Budapest. 

And so, in 1939…

ANANYO BHATTACHARYA: She actually returns to Europe… Klari goes back to try and convince her parents and, uh, von Neumann’s mother and brother, uh, to leave. Klari manages this but she stays to conclude family business and wrap things up.

KATIE HAFNER: Johnny’s letters suggest that Klari’s father dragged his feet in leaving Budapest, and that he wanted Klari to see to some important matters—perhaps liquidating some assets, or selling off property. All of which kept Klari in Europe for too long… 

ANANYO BHATTACHARYA: Johnny is, uh, writing to her desperately.

JOHN VON NEUMANN:  Darling,  For God’s sake do not go to Pest, and get out of Europe by the beginning of September! I mean it! Don’t be a fool. Come back!

GEORGE DYSON: He knew how bad things were in Europe and how it really was a matter of life and death to get out of there. 

KATIE HAFNER: Klari knew it was dangerous, too. Like many other Jews in Europe, she and her family had converted to Catholicism–as did Johnny–to stay safe in the face of rising anti-Semitism.

ANANYO BHATTACHARYA: She was really quite extraordinary…She had the most remarkable presence of mind.

KATIE HAFNER: Klari set sail on August 30th, 1939. Then, just as Johnny predicted, on September 1st…

ARCHIVAL TAPE: These are today’s main events, Germany has invaded Poland. 

ANANYO BHATTACHARYA: She also clearly was quite lucky because she jumped on that boat just in time.

KATIE HAFNER: So as war broke out in Europe, Klari was sailing towards her new life in the United States.

It might not be surprising to hear that someone on marriage number three by age 27, was prone to discontent. And, when faced with discontent, Klari took action. 

She was constantly gambling, taking chances on unusual characters and dipping into new, strange worlds. But her letters and memoir don’t reveal a thoughtless or frivolous person. Just like the Monte Carlo experimenter, Klari was harnessing randomness towards her own ends. She was striving for something, willing to completely upend her current life for the hope of something more and better…

Next time on Lost Women of Science…where that got her.


This has been Lost Women of Science. Thanks to everyone who made this initiative happen, including my co-executive producer Amy Scharf, producer Sophie McNulty, associate producer Ashraya Gupta, senior editor Nora Mathison, composer Elizabeth Younan, and the engineers at Studio D Podcast Production. 

Thanks also to our voice actors Eva Szabo and Nandor Tary, as well as our many Hungarian translators: Agi Antal, Rick Esbenshade, Charles Hebbert, Laszlo Marcus, Alina Bessenyey Williams, and Lehel Tary.

We’re grateful to Mike Fung, Cathie Bennett Warner, Dominique Guilford, Jeff DelViscio, Meredith White, Bob Wachter, Maria Klawe, Susan Kare, Jeannie Stivers, Linda Grais, Rabbi Michael Paley, Marina von Neumann Whitman, George Dyson, Thomas Haigh, and our interns, Hilda Gitchell, Kylie Tangonan, Leeza Kopaeva, and Giuliana Russo. Thanks also to the Computer History Museum, to Paula Goodwin, Nicole Searing and the rest of the legal team at Perkins Coie, and to the Institute for Advanced Study, the Library of Congress, and the UCSD Special Collections for helping us with our search. Many thanks to Barnard College, a leader in empowering young women to pursue their passion in STEM for support during the Barnard Year of Science. 

A special shout out to the Women’s Audio Mission in San Francisco, where this podcast was recorded. 

Lost Women of Science is funded in part by the Gordon and Betty Moore Foundation, Schmidt Futures and the John Templeton Foundation, which catalyzes conversations about living purposeful and meaningful lives. 

This podcast is distributed by PRX and published in partnership with Scientific American.

You can learn more about our initiative at lost women of science dot org or follow us on Twitter and Instagram. Find us @lostwomenofsci.

Thank you so much for listening. I’m Katie Hafner. 

[The above text is a transcript of this podcast.]