Einstein in Prague - The path to discovery

Saturday, April 3, marked 110 years since Albert Einstein arrived in Prague for his tenure as a professor of theoretical physics – 16 months in his life that were often overlooked in the past. Einstein in Bohemia by historian Michael D. Gordin, published in 2020 by Princeton University Press, changed earlier perceptions of Einstein’s time in Prague as unimportant. On the contrary, Gordin’s research shows that it was in Prague that Einstein shifted full-time to the study of gravity, which put him on the path to his greatest discovery in 1915: general relativity. In Prague, Einstein was also confronted with questions of identity he had not faced before.

A young Albert Einstein on a British stamp commemorating his greatest discovery: the Theory of General Relativity.

I spoke to Michael Gordin on a line to the US, asking first what Albert Einstein had meant to him as a youngster growing up.

As you might imagine I was always fascinated with Einstein, even as kid, although I obviously didn’t understand the science until high school, when I was introduced to special relativity. I had seen the posters and the quotations and he was very charismatic and photogenic, so I had a vague understanding of who he was. His brilliance had an appeal that lasted even when I grew up.

As an historian of the physical sciences, I had a general understanding of the arc of his career and his achievements, but I had always thought about him biographically, even before starting this book: looking at his life as a unit and bending the events that happened around him to make a coherent life story. It makes sense that most of the books written about Einstein are biographical because he is very appealing as a character, significant as a person, and his life is fascinating: he intersected with many of the currents of the 20^th century.

But upon writing the book, I wanted to see if I could go the other way: instead of bending the events so his life would be foregrounded, I wanted to try and tell the events centrally and instead bend Einstein. As a result, Einstein is not always the main character of the book, although he appears in every chapter.

My feeling beforehand was that Einstein was going to be the central character of the book but the more I researched, the more he became a character among several others, one of which was the city itself. That was a productive realisation and a real change in how I thought about him.

Einstein in Prague

The book covers a very specific moment in Einstein’s life that is often completely overlooked: when he got a full professorship at the German University in Prague and lived here for 16 months. It came practically at a midpoint between 1905 and 1915, the dates of his biggest breakthroughs. Were there similar breakthroughs in 1911 and 1912?

There were not. I suppose when I set out I had a hope I would uncover a secret breakthrough, but there wasn’t one. In the end that turned out to be part of the appeal for me in researching the book: I wanted to look at a period in Einstein’s career and to see what it looked like at a moment when he wasn’t in the middle of an earth-shaking discovery. That is, when he was working as an ordinary scientist, as “ordinary” as Einstein ever was, someone working on various projects.

He was already very well-known in scientific circles for his earlier work: the publications in 1905 on Brownian motion, special relativity and quantum theory, but he wasn’t world-famous yet. He wasn’t yet at his peak achievement, general relativity. It can appear that he was between things but he was living a very productive career even if he wasn’t the “Einstein” that we think of when we think of him now. And so 1911/1912 was a good way of capturing that: a productive scientist who knows he has already done great things and hopes to do more in the future.

But there something very important did happen in this period: it was the moment when he shifted his attention away from working on quantum theory to thinking full-time about gravity (which would eventually be the grounds for general relativity). Both historians and members of the public tend to think about breakthroughs and looking at those specific moments, and this book instead looks at how he was just starting on that path to general relativity. It can be quite revealing to look at a period when he was starting on a new project. During this Prague period, he finally had the time to start on it.

How did Einstein describe this moment in his letters?

Einstein always worked very hard and a constant refrain in his letters from Prague is that he was “working like a horse”; this was not unique to his Prague period, Einstein always worked very hard. He also encountered many roadblocks. The theories he developed in Prague were promising but didn’t work and he realised that. In one case he chose to submit something for publication despite a mistake and told the editor to publish it anyway, as it would be useful for people to see the mistake. So he himself thought of his work as an elaborate process of trial-and-error.

Prague's famous astronomical clock. Einstein realised that his static theory was a dead end and began thinking about time and space differently.

From the static theory to general relativity

What was the theory he was pursuing?

He was attempting to generalise his special theory of relativity from 1905, that looks at making frames of reference equivalent. But the special theory only looks at them when the frames are moving at a constant speed. What he wanted to do was see what would happen if he incorporated acceleration into that. Two years later, in 1907, he realised that if you did that the result would look a lot like a theory of gravity. That was an insight he had that he was very excited about, but didn’t have time to work on because of his focus on quantum theory.

There are two reasons, I think, why it is important to pay attention to the static theory. The first is, that even though it didn’t work, it still got him on the path of thinking through the hard questions and the realisation that the geometrisation of space-time was going to be necessary. That’s the path he took from when he returned to Zurich after Prague in 1912, straight through to the end of 1915 when he published the theory we still have. That’s the first reason: the failure was in itself the beginning of a success. What happens when he arrived in Prague is he immediately started working on exploiting this insight about gravity and general relativity being the same theory, and he worked hard at it. But it turns out it doesn’t work. The reason why is because what he called his “static theory” had a space-time that was flat and Euclidean – instead of bent and curved and warped, which is what he worked with later. Over the course of 1911 and 1912, he realised that the theory wouldn’t work in the way he was approaching it and that he would need to modify the geometry of space-time and use a much more elaborate mathematics in order to capture the insights he was interested in. He didn’t know the math yet and understood that he would have to develop a whole new set of skills.

The second reason is that while he was in Prague working on this he realised that one way you could test a theory of gravity was to look at the bending of starlight around a heavy astronomical body such as the sun. In the fall of 1911, he began discussions with astronomers to measure starlight during an eclipse so he could test some of his ideas. Leo Pollak, an astronomer at Charles University, put Einstein in touch with Erwin Freundlich from the Observatory of Berlin, who set up an eclipse expedition in Crimea in the summer of 1914. But of course the First World War broke out. Freundlich was interned by the Russians as an enemy alien and didn’t make the measurements: those would be made only in 1919 by British astronomers with a very different theory – full general relativity – and that made Einstein very famous.

The result is that while many in the past skipped over Einstein’s time in Prague, it wasn’t unfruitful.

It was rewarding both scientifically and also personally: he made connections in Prague that at the time may have seemed ordinary or everyday but which would have a lot of implications later in his life.

Prague as a character and as memory

You talk about Prague as also being one of the “characters” in the book: what kind of a city was it? As you mentioned, it was a few years before the war, and although the inhabitants didn’t know it at the time, huge changes were around the corner. Eventually, it would be the capital of an independent Czechoslovakia in 1918.

I like to think of Prague as both a central place and a marginal place at the same time in the context of the Austro-Hungarian Empire. It was the third city in the empire, behind Vienna and Budapest, but it was still extremely important. Bohemia and Moravia were economic powerhouses in the empire, and Prague sat at the midpoint of the train line between Berlin and Vienna, so it was an important connecting node between the two metropoles in the German-speaking world.

Prague at this moment was a very dynamic city, with a lot of economic and cultural activity. In terms of literary achievement, there was the development of Czech language letters at this time, although the take-off of Czech modernism really began around 1911 or 1912. In terms of German belles lettres, that had started with Rainer Maria Rilke already writing, joined at this moment by Franz Werfel, Max Brod, and little bit later Franz Kafka. Much like Einstein they were at a kind of middle point, following an achievement, and not knowing what yet lay ahead.

Prague to me feels the same way: it was very vibrant with a lot of cultural and economic ferment and, at the same time, it was not the capital of an independent country yet and it was not obvious in 1911 or ’12 that it would ever be so, nor that the Austro-Hungarian will be prove to be so brittle.  

In the book, I am interested in the connections and the kind of overlap, if you imagine those circular Venn diagrams, between Einstein and Prague – and the parts here they overlap. Sometimes the story takes place after Einstein is gone and sometimes the story follows the remnants of Einstein’s experience with Czechs and Germans from Prague as well as how they continued to shape his life later on. So the city itself is a character, as is the memory of the city and the relationships that he built while he was there.

The fact that Einstein spoke German but not Czech also influenced his interactions. Is it fair to say he was isolated?

He was indeed a little isolated. If you look at the census, around 23 percent of the population in the Czech lands listed German as their everyday spoken language, but in Prague the number was far lower: only about seven percent. Within that community, the Jews were split into two groups: there were more Czech-speaking Jews than German-speaking Jews. The German-speaking community, despite its small size, still occupied many elite positions in culture but also in banking and so on. Finally, a huge part of the city was bilingual.

I don’t want to reduce it to language and demographics, but Einstein arrived at a city where, speaking only German, he was confined to certain circuits. The most obvious circuit would be the professors at the German University, who tended to be older and more politically conservative than him and he didn’t enjoy their company very much. So he ended up being isolated in that way. He did find some German-speaking friends among educated Jews, which I think was a surprise to him. He didn’t break into the Czech community at all during this moment in 1911 and 1912.

He met a few Czechs when he came back to visit in 1921 and met many more later in his career, interacting with them in either Germany or the United States. When he encountered Czechs in Prague in his classes, they were Czechs who chose to speak German and attend the German University or work there, such as his first assistant Emil Nohel, who came from a Czech farming village but chose to study mathematics at the German university. His circle of friends in Zurich was not that much larger than this, but he was only in Prague for a short time and did not have time to build up many friendships, so he was in as sense isolated and worked all the time. I don’t think he was necessarily unhappy, but the strain of isolation was felt more by his family: his wife and two sons.

A plaque at the White Unicorn commemorates Einstein's attendance at the Fanta's literary and philosophy salon on the Old Town Square. 

First acquaintances, music and meeting Franz Kafka

What did he do for intellectual satisfaction or entertainment?

Einstein played the violin and met with a quartet. He wanted to play in a string quartet and they performed Mozart and Bach most, which were his favourites. One of the auditors in his class was Hugo Bergmann (who becomes a major character in the book) and he took Einstein to the salon of Berta Fanta, his mother-in-law. She was the wife of the pharmacist Max Fanta, who owned a pharmacy on the Old Town Square called The White Unicorn [Editor’s note: Throughout the 1990s the former pharmacy was a sci-fi, fantasy and tourist bookstore]. Einstein first went there with Bergmann and would play music with other string players, and at one point the novelist, journalist and translator Max Brod accompanied him on the piano. So he met an interesting set of people in that world — mostly Jewish, but not entirely, and well-educated.

At the salon they also held lectures about what was going on. Einstein gave a lecture on relativity in May 1911 shortly after arriving, which shows how quickly he entered that realm. At one of those meetings, probably that one, Franz Kafka was present. We know this from one year we have of Brod’s diary — that Kafka came to one meeting with Einstein but not the next. The diary includes this moment. Kafka and Einstein probably met and shook hands.

The Kafka meeting of course captures the imagination straight away and it is fascinating to imagine all these great minds coming together in this small space. But the impression is overblown, correct?

I always feel like a bit of a spoilsport when describing this episode, because it was fairly insignificant. It is so obviously what would happen if we were writing the movie: one of the greatest minds in science, the other one of the greatest minds in literature, both of whom transformed their fields, both of whom are of Jewish extraction, meeting in this small room. You want to believe that everybody lines up — and it just doesn’t happen.

It’s frustrating because they probably did meet each other. The reason I think it was insignificant is, first of all, because Kafka just didn’t go to the Fanta salon that often – he didn’t like the salons as much as Brod – so he and Einstein may have interacted  as many as three times or just the once. But here’s what’s strange: afterwards, neither of them remembered it.

Einstein became world-famous in 1919: everybody was talking about Einstein, and Kafka even mentioned relativity theory to a girlfriend in a letter in the early 1920s. But he never said “Oh, and I met Einstein” or that it was in some way an important meeting. There is never any mention of that. Which is strange. Not only did Brod continue corresponding with Einstein (sometimes with a decade gap in between), but he often referred to his interaction with Einstein in Prague as an important moment.

Also… Einstein lived to see Kafka become famous after the publishing of his novels after the writer’s death. He was aware of them. Thomas Mann gave him a book of Kafka’s, I do not recall now if it was The Castle or The Trial, but he didn’t like it. Einstein also never said “Oh, I remember meeting that guy” whereas he remembered Brod. So neither man attributed much intellectual significance to their meeting. Even if it did happen, it didn’t happen the way we want it to have.

I was imagining the movie the second you said it (laughter).

Yes, it would have been fascinating if Kafka could have had a bigger role in the book too; at the same time, I am still happy with the density of the connection. The fact that there is so much scholarship about Kafka was enormously helpful in teasing out the cultural milieu that Einstein experienced. We know a lot about the Fantas in part because Kafka was associated with them. There has been a lot of research, finding their correspondence, locating manuscripts, but the [Kafka-Einstein meeting] was a missed opportunity, as sometimes happens.

 Identity: Jewishness, Germanness, and Zionism

In Prague, Einstein was confronted with questions of identity: he was secular Jewish, born German, with Swiss nationality: while here, did he begin to think about his identity more?

Prague definitely forced him to think about his own identity, differently. It depends on what you mean by confrontation and whether it was sharp or aggressive, but I definitely think it was important. It marked him in a certain way, especially his Jewishness. (I’ll get to his Germanness in a moment). When he arrived he had to swear an oath to the Kaiser in Vienna as a civil servant in the Hapsburg Empire, and he wrote in the documents that he was without religion, which is also how he was registered in Switzerland. The German word is konfessionslos. It’s an important kind of registry because some of your taxes would go to support Churches by population, so saying what your faith had implications for the census and tax bureaux.

In Bohemia, he wrote down konfessionslos in the form and the Habsburg officials crossed it out, saying you can’t swear an oath if you don’t believe in God. So he had to have a religion. They wrote in mosaisch instead, and years later Einstein would joke that it was the Habsburg empire that made him a Jew.

Also important while in Prague was that he encountered Zionism as an intellectual movement. He may have heard about it before, but it hadn’t registered. He had been interested in Judaism at age 11 and 12, he studied for a bar mitzvah and then he stopped. He decided that he didn’t believe any of it and focused his attention on science instead. From that age, until the age of 32 in Prague, I think he probably had very little connection to the traditions and the community. But in Prague he got to know Hugo Bergmann, who later became an important philosopher and an administrator at the Hebrew University in Jerusalem, and Max Brod; both were very engaged in Zionism.

Zionism had an important intellectual home in Prague in this period. The famous philosopher Martin Buber gave his three lectures about Judaism in Prague, an important Zionist moment that galvanised the student population. A lot of the discussions at the Fanta salon were about Zionism, but in 1911 Einstein didn’t care for it. He disliked the idea because he thought of it as medieval – both backward looking and nationalist. He was strongly opposed to all forms of nationalism, which he saw as militarist and dangerous, and preferred to think of a community of humanity, linked to his own pacifism.

So Zionism didn’t register as anything he wanted to be associated with - that only happened later, in Berlin in 1918 as a reaction to anti-Semitism that he observed. When he began to grasp more about the movement at that time, and started to look into engagement, he was put in touch with Hugo Bergmann again, who was now in London. Prague situated Einstein: both in terms of “the world was going to classify him as a Jew no matter what he thought about it” and eventually that Zionism didn’t have to be nationalist and was something he could become involved with. That’s the Jewish side.

He also thought of himself differently as a German: for the first time as a German-speaker he was part of a minority, which was not the case in Germany or Switzerland. He was conscious of the Czechs seeing him not as Jewish but as German, so he began thinking about himself as a German, and that took root in Prague.

Why Prague?

I wanted to ask about how it was that his first professorship offer came from Prague. Why here and not somewhere else?

When he published his first papers in 1905 he was at the patent office in Bern because he could not find an academic job. So he became well-known among scientists without being established in an academic context. He then started teaching a bit at Bern and got a sort of untenured position in Zurich. The first big offer came from Prague. [In hindsight] it may look surprising, given he was already known in scientific circles. But back then, it’s easy to forget that 31 or 32 was very young to be offered such a position. It was Prague that first saw the possibility.

A different way of looking at it, is how come Prague was willing to take a chance on someone who was in his early 30s rather than someone more established with a longer track record? The answer is that he was strongly recommended by people like the Berlin physicist Max Planck and other leaders of science; who wrote letters saying that Einstein was the best possible choice.

It also had to do with the local tradition in Prague. Ernst Mach was an extremely influential physicist and philosopher of science who had taught in Prague for almost 30 years before moving to Vienna in 1895. His tradition in the philosophy of science and his way of thinking about scientific concepts had been very influential on Einstein – and it shows in his work. The people at the German University who remembered Mach thought of Einstein as a way of connecting to that older tradition. They were excited by the philosophical implications of Einstein’s work as well as its theoretical and physical insights.

A plaque commemorates Einstein's tenure as professor at the faculty in Prague's Viničná Street; his bust at his home in Prague's Smíchov.

At what point during his sojourn – his 16 months in Prague – was Einstein happiest?

That’s a wonderful question. I would say there were probably two moments that stood out the most. The first was the summer of 1911. He didn’t go anywhere, he told everybody he was just going to work on the gravity theory, he liked his library, he was happy with his office, and he spent a lot of time really focused on the science. It was summer, it was warm, the weather was nice and they could go on walks and the family was happy (they got unhappier later) — that was sort of a golden moment for him. When he wrote to people in August and September, it sounded like he was going to be in Prague for a while and that was what he then intended. But then he got a number of job offers in December. So he left in the summer of 1912 — but that wasn’t what he had planned.

Einstein used to walk over Palacký Bridge to get to work. The spires on the left are newer, built after WWII. Compare to the book's historic cover.

The second important moment is in the spring of 1912 when he met a very interesting theoretical physicist, Paul Ehrenfest, an Austrian whose wife was Russian, who had been working in St. Petersburg, who became a very important friend. He and Einstein shared many similar views on science but also on cultural and political questions. Ehrenfest was looking for work outside of Russia and so he traveled around and stopped over in Prague. He met Einstein and the two really hit it off. It was a bright spot for him and they remained close friends right up until Ehrenfest’s death in the early 1930s when the Austrian committed suicide, a loss that affected Einstein deeply.

Czechoslovakia’s First Republic as a democratic hope

One thing you make clear is that there are different Einsteins at different periods: the Einstein in Bern, then Berlin, and much later, Princeton, where you teach. Ultimately, who was the Einstein in Prague and was Einstein defined by Prague, at least in part?

I would say he was. I am not sure he always thought of it consciously but there were definitely a couple moments where the time he spent in Prague defined him in the future. One was his engagement with Jewishness and Zionism that was very complex. He was interested in some parts of Zionism but not others — such as building a state or anything military — and he ended up being quite disillusioned later in life.

Also, politically, he wasn’t very engaged with Czechs while he lived here but after he left, he came back one more time in 1921. And then he was enchanted, for a very specific reason: it was now an independent country, it is no longer a monarchy, which he always had a problem with. And it was the state with in Central Europe that had minority protections built into its framework, for the Germans and explicitly for the Jews, which was something that Brod was really involved in lobbying for, and this really impressed Einstein.

That is why he joined in nominating T. G. Masaryk for the Nobel Peace Prize for his protection of minority rights. He was very taken with Masaryk, who he thought of as an exemplary statesman and so was interested in Czechoslovakia as an experiment and as a democratic future for Europe. When the Munich Accords happened in 1938, dismembering Czechoslovakia, he saw that as a very dark moment for Europe. That is another way that Prague shaped him: the model of the First Republic was very important for him.

There is a third way that it influenced him that is harder to pin down. In the book I quote at length a letter he wrote to Max Planck in 1933 – the year that Hitler came to power in Germany and began to implement restrictions against Jews. Einstein was transformed into the world’s most famous refugee: very widely known and famous and very outspoken about the crimes that are happening in Germany.

The Nazi state hated Einstein. Even before they took power the Nazis were obsessed with Einstein: he was a pacifist, he was a socialist, he was Jewish – everything they disliked. Planck wrote to him saying he and his colleagues were trying very hard to try and save science and intellectual life in Germany and every time you [Einstein] speak, the Nazis go crazy and it’s very hard for us to do anything, so could you moderate it a bit?

Einstein responded by saying he was not interested in moderating his approach and asked where the German scientific community was when the Nazi press was attacking him. He then turned the argument on its head: he challenged Planck by asking how he would feel if the Czechs had suddenly begun enacting similar laws and restrictions against Germans at the German University in Prague where he himself had been a professor. He used being German in Prague as a metaphor for being Jewish in Germany. And he asked Planck whether he thinks it would be inappropriate to speak out if that was how Germans had been treated (which of course didn’t happen). Einstein reversed the frame because he had been a professor at the German University in Prague. This shows how his Jewish and German identity really became mixed together in Prague. And that mixture continued to shape him in the decades that followed.

You put the tragedy that was to come into high relief there, beginning with Munich and the dismantling of Czechoslovakia.

As far as I know, Einstein never addressed the expulsion of ethnic Germans from Czechoslovakia after the war – that did not interest him then, but this did, in the 1930s.

If we turn back to Einstein’s great scientific contribution, general relativity, it is still incredible, isn’t it? As a sheer intellectual feat?

To my mind, the Theory of General Relativity it probably the most important and exciting intellectual achievement of the 20^th century. It is a staggeringly impressive feat of thinking. To take a problem which people really weren’t worried about (after all we’d been relying on Newtonian gravity since the late 17^th century and it is was pretty reliable and accurate) was remarkable. With Newton there were a few minor problems around the edges but nothing that anyone was that worried about. None of it would matter because no one was traveling to other planets, no one was dealing with cosmic events. And here you have a person who just thought logically about how to understand how space and time and motion interact and out of that comes a theory of gravity that is incredibly complicated but incredibly accurate.

It’s so accurate that it is still use it, it is how we calculate how things like black holes operate. We can now take photos of black holes. Things that we never thought possible can be done because of this theory from 1915 that was worked out by Einstein in discussion with very few other people. It is how GPS coordinates are corrected to compensate for the distortions caused by Earth’s gravitational field. We need general relativity for that too. None of this was imaginable at the time that Einstein was developing the theory. It was a fascinating and quite unintuitive way of thinking about the world: that space and time are warped by matter and energy to create the force we know as gravity. That idea is still staggeringly effective and so intricate and appealing that people are still pondering the nuances of what it means. It is an extremely significant achievement.

Since it was published, Einstein in Bohemia has gotten some great reviews – it must be very rewarding for you as an historian to have gone through this process and to have brought this all to life.

It was and it still is and I am so excited that people are interested. In a way, I wanted the book to show people who may not know the richness and history of the place, and the richness of the Czech and German traditions there, through Einstein. I wanted to bring that to a much broader readership and I hope it has served to that end.