The Historical Max Planck ▸ by Brandon Brown

Thanks so much, Tony. I'm absolutely delighted and honored to be here. To hear from someone like Tony, of Tony's stature, of Tony's authorship, was an amazing moment. And it's been a wonderful, wonderful visit so far. Thanks so much for coming out. When I was 19 years old, a sophomore in college, starting to study modern physics, luckily I had a professor, the name of Barry Dunning, who mentioned as an aside that Planck was confused by his own discovery for quite a while. And as maybe a confused student, this really appealed to me. He was automatically a sympathetic character. And we have this side column photo, which we've all seen. It turns out this is in mid-1933, which was a very traumatic time for Germany, and Max Planck in particular. But I did wonder at that age, I know physicists need this stern countenance in their side column photos, but this man seems especially sad. Before I forget, credit archives I've worked with. They were amazing. That's at the Max Planck Society for the History of Science in Berlin-Dahlem with some friends there. In a little chair, I was lucky enough to sit in for quite a while. I really want to thank Tony for the invitation and the whole Kavli Institute here. Everyone's been so friendly. It's been great to absorb the ambience of this place. Dr. Imke Listerman is actually a PhD molecular biologist who is bilingual and just happened to be visiting UCSF. And we became friends. I worked with her husband. And she ended up helping me with a lot of translating between my English and her German. We did a lot of moving things from the original German into English. Professor Emeritus John Heilbronn, longtime Berkeley science historian, had written a great book on Max Planck that I like to refer everyone to. I leaned on it in a non-trivial manner. And that's called Dilemmas of an Upright Man. My book is a little more interested in Planck's science and Planck's family. And his book is a little more interested in his life as an administrator and leader. And maybe because I did four years of administration, I said, oh, that's enough. That's not as interesting to me. Dieter Hoffman is a German expert on Planck. I think he's in the middle of sort of an 800-page German version of Planck's life. He's been very gracious and spent some time with me in Germany. Professor Horatio Camelong might be someone you guys would really enjoy from a theoretical perspective. He's my chief theoretical colleague and friend at the University of San Francisco. He's doing a lot of work on quantum anomalies right now, et cetera. But he and I had many long lunches about how to describe some of the physics topics for a lay audience. And those were some of the most fun collaborations of the book. What I want to talk with you about today are people in Max Planck's life. He was kind of a central hub for all kinds of interesting people, as you know, and you'll learn some others today. Few physics notes. I don't need to teach much physics to this audience clearly, but there are some interesting wrinkles out there that aren't typically known. You might find interesting. Times and trials. He had an amazing, we were talking about just a minute earlier, really cinematic and tragic life. And I'm especially interested in why we know his name so well today. So I want to talk about his dramatic rescue and the rebranding of German, not just science, but German academia, really. Max Planck is here in the little checkered shirt. At that point, the youngest of four. And then he had one younger brother from his two parents, two older step-siblings. He stayed very close with his brother, Adalbert, who became an engineer. And Adalbert's children, two of them, came to America. And we have some letters in American archives from Max Planck. There weren't too many that survived, by the way. Part of the difficulty, and why there might not have been more in terms of a Max Planck biography, is that so much of his personal writing and effects and journeys, a rigorous journal keeper, but almost everything was destroyed in World War II in the Allied bombing of his house. But Planck was born in Kiel. And there was not a Germany proper at the time. The Schleswig-Holstein region actually reported to the Danish king there on the Baltic Sea. When he was about eight, the family bravely as an academic family, his father was a professor of jurisprudence, moved to Munich, where Max Planck did most of his education. Now, when he was about 12, his older brother, Hermann, was killed in the Franco-Prussian War as a German ally. Well, they weren't Germany at the time, but the Prussian and Bavarian forces rapidly moved across France. He died in that conflict. And then we have kind of the modern state of Germany, united by the Franco-Prussian War. And one wonders if the Planck family felt especially tied to the German state with family blood in the seams. Influences, just briefly, the amazing Hermann von Helmholtz. It's interesting to go through these histories and learn that he was not just a German celebrity, this polymath who covered all kinds of fields in biology, sensory biology, and all over physics, of course. But he had international acclaim. When he came to the United States in the 1890s for a World's Fair and then the big sort of electrical convention, he met with leading politicians and was really heralded in newspapers. And it was a big deal to have Helmholtz visiting the United States. In college, Planck spent one year away from Munich. This was typical. He spent a year in Berlin. And he studied with the two physicists there, took their classes, I mean, Helmholtz and Gustav Kirchhoff. He and his friend, Max Planck, and his friend who became the mathematician Karl Runge, used to joke about how bad these two professors were. So Helmholtz was very unorganized and hard to follow. And Kirchhoff was almost robotic. Planck apparently eventually erred on the side of Kirchhoff by all accounts as a lecturer. Clausius, though, the work of Clausius really fired Planck like few others. So he was very, very interested in what was then this fairly new idea of the second law of thermodynamics and entropy. And sad story. Planck's early career was off to a very slow start. This also interested me as a student, I think, in that I was given a sort of parade of 23-year-olds, maybe a 29-year-old with these amazing breakthroughs in physics. And Planck was middle-aged when he stubbed his toe on the quantum. But when he finished his PhD thesis, which was a follow-up to Clausius' work on entropy, I mailed him the manuscript, sent him letters, never heard back from Clausius, finally went with his thesis under his arm, took the train to Bonn, and showed up at Clausius' doorstep. But the family was away. And he never did get any feedback from Clausius on his PhD thesis. And Helmholtz, according to Planck, never read it. And Kirchhoff disagreed with Planck's thesis categorically on the second law of thermodynamics. Things started to improve for Max Planck really when he started to work in physical chemistry. And still his most cited papers today are some work he did in the 1890s as a fairly young professor in physical chemistry and the voltages that arise between fluids of different concentrations of electrolyte and these kind of things. Van Hoff also moved to Berlin when Planck was getting started there. And so this association with physical chemists brings Max Planck into the fold of atomism before a lot of other physicists, which turned out to be key to his success. Outside of physics, he was a great fan of Immanuel Kant. And this sort of gives you his system of thought and his philosophy. Planck wrote a lot of philosophy of science later in his life. Not critically acclaimed, but he was a man of many talents. And the poet and playwright Goethe was a Planck favorite. And in fact, a lot of quotes you see, even in Germany, attributed to Max Planck. This is on a construction fence. When I was in Berlin, they had this picture of Planck talking to a modern day student and saying, in essence, so when one quits, when one stops making errors, so that must be the time that one has quit working. And some student has scrawled, so total happiness. But anyway, this is actually derived from Goethe. And a lot of things that you see credited to Planck, he was trying to quote Goethe. With his late start in academy, he lived with his parents in Munich for several years after his habilitation. That's essentially a German postdoc at the time, waiting to try to find a real academic job and teaching almost for free in sort of an adjunct status in Munich. And he wanted to marry a good friend's sister, Marie Merck. Once he got a job through his father's connections at the University of Kiel, he's back to Kiel, this small, historically important naval town. He takes an academic job there and marries Marie. They were both very much into music. Planck, if you hadn't heard this, was a concert grade pianist. And early on, thought he would go into music. He just felt like he didn't develop the bug to help him keep composing. But he had written a little opera in college called Love in the Forest and whatnot, maybe about Marie. We don't know. They had four children. The first three I'm showing here. So by 1890, there are three kids in the house. And Planck has accepted a position in Berlin that he would hold then for essentially the rest of his life. That's Carl in the middle, poor troubled Carl. And the twins, I like to think I can tell them apart. Emma on the left and Greta on the right. And we'll come back to them shortly. A few years later, their fourth child together, Erwin, was born. And this became one of Max Planck's best lifelong friends, Erwin. More about him later. Heinrich Hertz is an interesting contemporary of Max Planck. They're about a year apart in age. And where people were kind of shrugging at Max Planck when he was a PhD student, they were celebrating Heinrich Hertz, inviting them into their lab, setting him up, set aside a little office space for him. Both of Max Planck's academic jobs in Germany, in Kiel and in Berlin, were first offered to Heinrich Hertz. And he turned them down in each case. Interestingly, Heinrich Hertz tragically dies very, very early in 1894, which becomes kind of a key year. And Max Planck starts on a road to scientific leadership. And that's when he starts studying black body radiation as well. Even he was preparing some remarks at a memorial for Heinrich Hertz, basically, and digging into Hertz's work again, and got fired up about electromagnetic radiation, actually. These are just a few of the most interesting people. Max von Laue, who's talking with Tony a lot today. Tony was incredibly generous with his time today. I had a great time speaking with him. Max von Laue, who probably deserves as much as anyone an enormous biography about him and his impact on physics, was Planck's favorite pupil. Got his dissertation completed in 1903. It was Max Planck's first assistant there at the University of Berlin for all. And they were lifelong friends. And as we'll mention later, and is prevalent in the book, in the war years, the von Laues were always checking in on the Plancks. Lisa Meitner was Planck's second assistant. When she was in Vienna taking lectures from Ludwig Boltzmann, and she was a real devotee of Boltzmann. When Boltzmann committed suicide in 1906, Planck was called to interview for that position. So Planck goes to the University of Vienna, considers a change of scenery. He loves the mountains. Ended up declining that job opportunity. But Lisa Meitner saw his job talk and said, well, why don't I, with Boltzmann gone, why don't I go to Berlin? I'll just pack my bag for Berlin. I'll stay a while. Maybe I can attend some lectures. So she showed up in Berlin and learned that women weren't allowed to attend physics lectures. But Planck wrote her an exception. And even though he had sort of old school views of women in science, he really started advocating for her. She became a close friend of the family. So one reason I mention her, and she's prevalent in the book, is while so much of Planck's material has been destroyed, Lisa Meitner spent a lot of time in America, of course, wrote voluminously. And she wrote a lot about her experiences with Max Planck. So this is one of the ways we have a window into his life. And he was an incredibly playful person at home. And lots of evenings of music, which she really adored. And she even went on hiking excursions with the family, et cetera. And she'll come back again later. And Max Planck, by the way, advocated for her position in this basement woodshop of the chemistry department, where she started collaborating with Otto Hahn. Leads all to their studies of nuclear radiation. Needing no introduction, of course, Einstein. But Max Planck was sort of, at one point, the book was called, when I was going to try to exploit this Einstein name like so many do, it could have been called Einstein's Elder. So they're one generation apart. And Max Planck came to the defense of Einstein early on. Arguably was the earliest and most important advocate of special relativity, 1905. Was the main theory associate editor at Annal & Der Physik in the miracle year of these publications coming in. And Max Planck saying, well, even the ones I disagree with, like the photoelectric effect thing he didn't like very much. But they're interesting. They're well thought out. Let's publish them. So they became pen pals right away. And early on, Max Planck said, look, this special relativity is going to get a ton of criticism. We have to stick together on this. They actually didn't meet till 1909. They met at a conference. And Max Planck started working right away to try to bring him to Berlin. And was finally successful in 1913 with a record job offer. But they became, they're incredibly different people. Planck is more, I think, this whole notion of the odd couple works for them pretty well. Of Felix and Oscar, where Max Planck is Felix. And a little much more reserved and serious and into decorum. And Einstein's a little more hard on his sleeve and jokey and mercurial. They had incredibly different politics. But they were really united by this deep belief in a fundamental and beautiful physics. There's some sort of villains in the book. The Nobel Prize winners Philip Leonard and this great picture of Johannes Stark. Stark was actually an early advocate of Einstein's. But as after, by the close of World War I and this rise of extremism in Germany, Stark and Leonard signed on with the National Socialist Workers Party, the Nazi Party, very early on. And even by 1923, they're pledging their allegiance to Hitler and saying things like, oh, Hitler's name belongs with Kepler and Copernicus and Newton and these great geniuses. And Leonard, of course, writes a book called Deutsche Physik, German Physics, decrying the movement of Jewish physics. And he often lumps Planck, who is not Jewish, but Einstein's friend. He often lumped Planck in there and would say, the Planck-Einstein cult. In the archives in Munich, I found a bunch of letters of Leonard writing to friends and colleagues of Max Planck's with regularity saying, you can't trust Planck. He's gone down the Dadaist mathematical road. He's in with Einstein. We know that path is corrupt. You can't trust Planck. So these guys were working behind the scenes. And Planck's friendship with Einstein in that way did cost him. In 1894, I don't have to tell you the story of black body radiation at all, but it's interesting. Helmholtz has passed away. On his way back from America, he fell in an accident on a ship and hit his head and later died, essentially, of a brain aneurysm. And Hertz died the same year. Planck writes a letter to a friend saying, this has been a really, really sorry year for my science. But he was ready for something new. And he embraced thermal radiation, especially after studying electromagnetic waves all over again. In Hertz's work, what I think is kind of interesting, maybe not that well known. I apologize if you all know this already. But essentially, Germany's version of NIST was very much into studying light bulb filaments at the time all around Berlin. Some of the leading experimenters in pushing out the boundaries of measuring thermal radiation from a hot filament were there. So there was an abundance of very technical data. And no one's studying it from a fundamental physics point of view, even though, of course, Planck's old professor, Kirchhoff, had suggested that there was this universal character. It's really Kirchhoff's suggestion that thermal radiation was universal, independent of material, is more incredible when you dig back into these old data sets. Because there were so many gray body effects, it didn't look very universal, actually. One thing I was surprised by in digging through this, some letters in the Lorentz archives showed that he struck up this little conversation with Planck while Planck was really trying to still, not successfully at this point, figure out black body radiation. He was really struggling moving from a classical framework to describe the thermal radiation curves. He had this side correspondence with Lorentz. They met at a conference. It was Lorentz's first conference at age 45, actually, in Germany. And he met Planck. And Planck said, oh my god, we really have to start introducing you to people and this kind of helped lead to Lorentz's emergence, politically within physics, if you will. They wrote back and forth on the ether problem. And Planck was convinced, after mulling it over with Lorentz, that the ether must really adhere to the Earth. That would explain the measurements. And that the speed of light couldn't depend on the ether density. But he closes the last letter with, look, I leave this in your capable hands. I'm going back to my other projects. I just mentioned this. It's interesting. So when Planck finally gets, in 1905, Einstein's special relativity notions, I think he was especially sympathetic at seeing some new ideas. And had studied the problem in some depth with Lorentz himself. And you probably know this part of the story. Thomas, if you're interested in these things, in the very start of Planck's ideas, I can't recommend enough the Thomas Kuhn book on the quantum discontinuity, tracing all those people's work in the very earliest stages of quantum theory. And he argues Planck probably gets too much credit. I kind of mulled this over in the book with some other sources as well. But when Planck was desperate to fit the thermal radiation curve, he recognized in the entropy, starting with the entropy, he needed something like this equation, which is basically placing p chunks of energy in n bins. And Boltzmann just came up with this permutability in 1877 with kind of a test case, something he abandoned within his so-called H-theory project. But this is exactly what Planck cited and used, then, for the energy distributed into the resonators inside a thermal body. Used that part and parcel. So that bit of combinatorics really launches the energy quantum. So I mentioned Dieter Hoffman as this German science historian. And when I got to visit him, he said, oh, I should get you a copy. If I can find one, there aren't many of the brief Taiga book. This is a letter diary. And I've looked into publishing this in English. I think it's so fascinating. But starting in college, Max Planck and three friends, including the mathematician Karl Runge, said, let's keep a journal, a joint journal. We will take turns. Every two months, a different person has it. And you write what's going on in your life. And we will mail it around. And they kept this going for over 40 years. And it documents these incredible times in Germany and their lives. Planck here lets his hair down, if you will. I mean, he uses multiple punctuation marks and things like that you don't see anywhere else. With this, it almost felt like an interloper seeing this book. So none of it has been in English mainly the parts I put in the book here. This is an interesting one. Physics-wise, in 1908, Runge says, OK, what is it with the quantum anyway? What is this quantum stuff about? I'm hearing more and more about it. And this is after it's been applied to specific heats by Einstein, right? Very interesting. Max Planck, when he never said anything is bold anywhere else, but he talks about it not as a state, but we have to think about it as a process. Interesting to note, Max Planck never did go with the whole quantum of energy idea. He always called it his constant, the quantum of action, which were its units. He speaks of an atomism in time and even mentions that maybe this Minkowski consideration of spacetime is worthwhile for looking at a granularity of spacetime. That's 1908. You guys might know better than I, but I can't find references to quantized time until you get to Levi in 1927, or of course, Earl Snyder spaces more technically in 1947. But I don't know if you can cite this personal diary so much. It's pretty interesting. Let's get into the times and trials. In 1909, Planck had an incredible year himself. He was invited to Columbia to give a series of lectures in German, of course. That was just lingua franca of physics. They were very popularly received, translated into English. You can find them now. That's sort of the state of the physics in 1909. His wife was very sick and didn't travel with him. He did love his time in America. There's still a couple of surviving postcards he sent to Max von Laue from the White House and things like that. And he always spoke very fondly of America for the rest of his life. When he got back, though, his wife's condition worsened. She had a lung ailment, and she passed away in 1909. Marie did. At the same time, the launching of the Kaiser Wilhelm Society, the Kaiser Wilhelm Gesellschaft. So this is Wilhelm II on the left. Interesting set of ghostly figures here in their top hats. This is Adolf von Harnack, Planck's essentially next door neighbor in their suburb of Berlin. And they became really close friends. Harnack was a theologian, a religious historian, who was just a huge fan of science. And he spearheaded the foundation of this society, which would do big science, big science problems that were bigger than just one university, or one or two professors, or one department that would use government funding to tackle some of these issues. This is Emil Fischer from the chemistry department, who was worried about Lisa Meitner being in a chemistry lab because her hair might catch on fire since she was a woman. That was Emil Fischer. And the tragic Fritz Haber here in the background, the chemist, who was also a friend of Planck's. Now, unfortunately, they tie. And the Kaiser had language like this, too. And this becomes this kind of German source of pride. The military and science are twin pillars of greatness. The years of World War I were incredibly tragic. And it's almost crass to go through in this format. But a deep impact on Planck's life. And a reporter once said in the 30s that understanding the weight of Max Planck's losses almost gave him a mystic-like quality, like a mystic of physics. But Karl Planck, who had struggled with depression, never found himself in a career, had finally brought on his father's pride when he enlisted in the military and really seemed to enjoy being in the military. But he died, as so, so many did, in Verdun in the spring of 1916. And Planck wrote to Wien, now that I understand my son's value, finally, now I must lose him. The turnip winter shortly thereafter was a time Germany, during war, had a lot of trouble maintaining food supplies, to say the least. So the turnip winter, that's all there was to eat. Turnip soup, turnip jam on boiled turnips, et cetera. And Greta, who had war married a German soldier, died in childbirth in 1917. And the rate of women dying in childbirth that year was incredible in Germany because of the poor nutrition. The daughter survived, Max Planck's granddaughter. And he helped raise her. And the widower then married the identical twin, Emma. Erwin, who had been captured very early in the war, spent about two and a half years as a prisoner of war in France, came home in October 1917, which greatly boosted Max Planck's spirits. They would trade journal entries to one another that Erwin had written from his internment and that Planck was keeping the family journal at home. And Erwin was a cellist, and so they would play their duets together. And sometimes Einstein would join them for trios, not infrequently, actually. The Kaiser abdicates in November 1918. And this is an interesting letter telling between Planck and Einstein's friendship. Right before the abdication, Planck writes to Einstein saying, I would really like to ask the Kaiser to step down. That would be the reasonable thing, but you can't understand. I would never be able to do that. I have what you don't understand, an unbreakable bond to the idea of the German state. Emma Planck died also in childbirth from the same husband who had remarried in November 1919. And that child also survived. And if I have the daughter straight, that child's daughter, so Max Planck's great-granddaughter, is sort of the heir apparent of the family and allowed me to use a couple of family images in the book. He's been very, very sweet about the project. Einstein, to have born as Planck's misfortune, rings his heart. When he saw him, he was staying upright, but he could not hold back the tears to see him. So Einstein would often just show up in this time with his violin and saying, let's just play music. We don't have to talk. Planck de Lorenz, I doubted the value of life itself. That's really atypical for Max Planck, even in his saddest time. So he'd soon rallied with his characteristic optimism. There are many high callings, he writes to his cousin. The value of life is determined by the way it is lived, so sort of stiff upper lip and onward. Between his mother dying in 1914 and Marie in 1909, in 10 years, he had lost three children, his first wife and his mother. 1920, this sort of provocative photo is actually the unveiling, apparently, the unveiling of the flag designed by the Nazi party, circa 1920. And it's interesting, because this is the summer of 1920, where Max Planck always summered on this very lake south of Munich, the Tegernsee. And whether Max Planck and his in-laws saw these nutty people out walking around the lake with their new flag, we can only speculate, probably not. But they were around the same parts at the same time. Max Planck becomes a Lutheran elder. He was a very religious person in his life, although he said he didn't really ever hold the Christian conception of God. He had a looser conception of God, but he really enjoyed working within the church. He gives his Nobel Prize lecture, which is really gorgeous. You can find that in translation, just some beautiful language about the process of physics and that in 1920. It's the 1918 prize, but it was awarded in 1919 after the war, and he couldn't go to collect it until 1920. He helped fund, with Fritz Haber, the Natgemeinschaft, which is an emergency funding organization, which is interesting. So as the German currency in the Weimar Republic becomes incredibly unstable, almost useless, he's doing some international fundraising to keep German science going. And one of his proudest accomplishments with that, he liked to say, was the early real quantum mechanics were funded with this. So Japanese industrialists, Americans, and people in the UK were donors to the Natgemeinschaft. It exists in a fledgling form. Smaller form to this day. And as I mentioned, the Nazi party forms that year. And Leonard writes Deutsche Physik. Like, let's get back to experimental, true German, proudful physics, and we can abandon this Jewish physics stuff that's so mathematical. That starts in 1920. When I started this project, I thought, OK, I'll have to deal a little bit with the Nazi stuff that's not my interest. I know Hitler comes to power in 1933, but to really dig in and see how much they affected Einstein's story and Planck's story as early as 1920 was sobering. Yeah, so as early as 1921, this firebrand speaker is in the street saying things like, science, once our greatest pride, is today being taught by Hebrews. And this is when Leonard and Stark get on his rah-rah bandwagon. 1933, which is the time of that really sad photo we started the talk with. There are a lot of photos of Planck from about that time. As far as I know, this is about the last photo of the two friends taken together. There's a wonderful joint interview they hold with a gentleman by the name of Murphy, an Irish journalist, who they were bringing some of Max Planck's essays into English for the first time. And he interviewed Einstein and Planck together. And they're obviously so fond of each other and so parallel in their thinking about how science works. When the Nazis came to power and Hitler becomes chancellor, Planck is encouraging a lot of caution, saying, I think this is like a thunderstorm that will soon pass away. New governments are bumpy. That was not an atypical German sentiment. When Hitler rose to the chancellery, Erwin Planck, who was in the cabinet, the last cabinet of the Weimar Republic, Max Planck's favorite, youngest son there, resigns his post immediately and recognizes the danger of being in the former government and actually leaves Germany on a long trip through Asia. In March, Einstein, who is already abroad, already flirting with many jobs overseas, speaks out from America about what he sees in Germany and the alarm that the world should be paying attention to these horrible events. Planck and Einstein then go through a series of heartbreaking letters between March and April. Basically, Planck's like, you know, airing this dirty laundry is ultimately going to be counter to your cause. It's counterproductive. And so Einstein's relationship with Germany is severed completely. And those are the last letters between Planck and Einstein. Although Einstein says, our friendship will always exist above these matters, you know, know that. But their friendship falls completely silent by 1933, and they never did communicate again. Max Planck requests a meeting with Adolf Hitler in May to protest some of the policies, especially policies applied to German science and chasing Jewish physicists from the country, et cetera. And he especially was saying, hey, we actually, you had someone like Fritz Haber that had to leave Germany. That's crazy. He even served for us in World War I, et cetera. And Hitler flew into a rage. It was a 45-minute meeting. We only have Planck's account of it. Hitler flew into a rage and said, people question my nerves. I have nerves of steel. And it just essentially started frothing at the mouth until Planck kind of backed out of the office. You can wonder if Hitler remembered that meeting later or not. But Planck was really crushed, and he also fell in line. He did what he could. He wrote as many exceptions for people as he could, but he also did his salutes to the flag and said his Heil Hitlers and fired Jewish staff members when it was required. And he pledged his support. He said, scientists cannot stand rifle at rest while we rebuild the German nation. When Otto Hahn suggested they hold a protest of scientists in the summer of 1933, Planck said, well, that was actually to Heisenberg. But he said, you cannot stop a landslide once it has started. And he told Otto Hahn, any of us that resigns their position, they will have 20 people ready to fill them who won't be able to do as much good on the inside as we can. So he really tried to make a positive difference on the inside. Now, this is a reader. So this is the first time I've told this story. I heard from William Cahill, who's an emeritus professor, I think, at Cal State Long Beach, a chemist. And he told me the story of his father, William Cahill Sr., who had studied in Berlin in 1933. I mean, it's easy to forget, but as a pinnacle of science, bright American students really wanted to study in Berlin. So William Cahill, the American, just starting grad school, goes to study with Carl Neuberg in Berlin. And Carl Neuberg is at the very beginnings of biochemistry and what does an enzyme do. It was very exciting work. This is a picture of William Cahill in 1933. They actually unknowingly rented Bertolt Brecht's abandoned apartment in Berlin, with all of Brecht's books still there. This is a very poignant photo of Cahill, who had just been issued a bright blue ID as a foreigner by the Nazis. Their Aryan roommate, who had his brown German ID, and their Jewish roommate, all fast friends with his yellow ID. But the story of Cahill is interesting, because as we see Max Planck is accommodating, he also sometimes stood up and bravely spoke. Fritz Haber, who had had to flee Nazi Germany as a Jewish scientist, died overseas in 1934. In 1935, Planck said, we must have a memorial. The Nazis forbade this, don't try to have a memorial for Fritz Haber. And Planck said, no, no, he stood with us. We're going to stand with him. We're going to have this memorial. So the Nazis said, no one can attend. Carl Neuberg, who was a Jewish scientist in Berlin, and had tried to stay around because he was so excited about the work. And people like Max Planck were saying, we can protect you. So Carl Neuberg was the advisor to William Cahill. And he told Cahill, I can't risk going to this memorial for Fritz Haber, but you can go in my stead. So we have this story through the family of William Cahill, who passed away in 2004 or 2005, attending this memorial and hearing Max Planck speak out, and speak out against the Nazi government, and how embarrassing it was. And the only good was that Fritz Haber never had to see the depths to which Germany was sinking. And he hoped things could be corrected before they went any further off the rails. But he was very bold in speaking the name of Einstein, which was verboten at the time, and speaking out against the Nazi government at this forbidden memorial in 1935. 1937, 1938, Max Planck loved hiking in the mountains. He tried to clear his head with these silent hiking expeditions, sort of the beginning of, I'm sorry, more late every summer, especially in the Alps. And here he is with Erwin. I don't know how well you can make out the image. And he was topping significant peaks, even at age 80, which would have been 1938. He's really shifted more into public lecturing at this point. And he's been criticized, probably rightly, by people like John Heilbron. He also did public lecturing outreach for science in occupied areas. So in that sense, he's literally part of the Nazi government giving, not pro-Nazi, but giving lectures as part of the Nazi government. But he was accused by the Gestapo of being a white Jew, and then actually investigated. And the Gestapo concluded that he was up to 116th actually Jewish. That seems to be completely false. But he was falling out rapidly with the Nazi government. In the Anschluss, the annexation of Austria, Lisa Meitner's citizenship from Austria becomes completely useless. So she is completely imperiled. And she escapes with the help of Otto Hahn and others in the cover of night to the north. So she survives and lands in Sweden for quite a while. The Nazis completely take over the academy in 1938. And Max Planck is finally forced to retire from his last positions, the German Science Academy. In 1944, there's the attempted briefcase bombing of Adolf Hitler and Wolfslehr, with mainly old military people left over from the Weimar Republic. Of course, they're just stirring this Nazi ant pile. And hundreds of people are arrested after Hitler survives this briefcase bombing. And Erwin Planck is arrested. So he'd stayed in touch with a lot of his old Weimar Republic buddies. He said, look, I wasn't involved in the bombing. There's no evidence that he was involved in the briefcase bombing. But he had written a post-Nazi Germany constitution. They were ready to take over the government with a new set of laws. And he had actually recruited people to the cause of the resistance. That's been proven. So in October of 1944, he was condemned to death at this sham trial of the People's Court, this kind of a ridiculous version of justice. And we have accounts now that he was tortured for months in jail to try to confess against other people, et cetera. He only, one of the few letters that made it out to his father, he just requested a copy of the Odyssey. So Max Planck sent him a copy of the Odyssey that he could read in his jail cell. He was finally, sorry, I'm really burying the sad punchline here. Max Planck worked every angle he could. He had few contacts of any use in the German government. But he did procure from Himmler the promise that the sentence of death would be commuted. So the hope is if they could just survive the war, Erwin would be free again. So they have that in January of 1945. But a few weeks later, at Hitler's command, Erwin Planck was executed just a couple of months before the end of the European World War II. And Planck was, of course, completely devastated. As Max Planck's home was damaged by bombing, he and his second wife, Marga, moved to, they were actually in that white estate in this lovely town west of Berlin, Rogatz. It's on the Elbe River next to this medieval tower. What happens, though, in spring of 1945, this becomes a battle line between American forces under Dwight Eisenhower and Nazi forces. So the Rogatz, the town, is on the eastern side of the river. The Americans come up to the river, exchange fire with the German forces. But Eisenhower basically says, I'm not interested in racing to Berlin with the Soviets. That's just a waste of human capital. And we need to get all this equipment to the Pacific anyway. But Max Planck and Marga flee an active war zone for days. And Max Planck is now 87 years old. And they're sleeping in haystacks and hiding in trees. They're completely on the run. And Max Planck is in failing health. But there's a rumor of his whereabouts. So this is sort of a military map. And this is the Elbe running here, and the Soviet forces closing quickly from the east, and the American forces up to the Elbe River. So a rumor of Max Planck's whereabouts, that he had found shelter with this milk farmer's family in a hut, made it to a young GI by the name of Gerard Kuyper, who had enlisted in the Alsos Project. It was a branch of the Manhattan Project, a secret group of scientists who would follow behind the Allied advance to ferret out what they could find of the German bomb project and Nazi science in general, and then try to capture all the German physicists they could. Planck was not of interest. He was not active in the German bomb program at all. But Kuyper said it would be a tragedy not to try to rescue him. So he got permission. This is a rare case of Alsos sending a jeep with just three people out past our lines to rescue Max Planck, and just hours before the Soviets would have captured Max Planck, bringing him back to the American side. And he spent his last two years peacefully with his cousin's family in Göttingen, and was again installed as a president of the Kaiser Wilhelm Society. It was a completely figurehead-type position at that point. He lived until he was 89 years old and passed away in 1947. So the Kaiser Wilhelm Society was dissolved. Germany split into four supervised parts right after World War II. And the German scientists remaining, the main figures that are still there, have gathered in Göttingen. And they appeal to Allied forces, like let us restart the Kaiser Wilhelm Society, and have seminars, and get what we can of our science back running. And the Allies sit with it and say, you know, this whole warlike guy with a pointy helmet and the skull and crossbones sort of stuff, it's not a good look. So they suggest you can do science, but we need a new name. Max Planck himself wrote, no, we don't want to rename it. But finally, they asked, can we use your name? And after a lot of hesitation, he did allow that to happen. So by 1948, in all three Western zones, the Kaiser Wilhelm Society was completely renamed the Max Planck Society, which it remains to this day. Of course, doing a lot more than physics. There are 82 institutes and tens of thousands of employees, not just in Germany, but around the world now. I like this picture of him. This is in Göttingen in his cousin's house. He still insisted on playing 15 minutes of piano a day, even though he had lost the use of a couple of fingers. He kept that, and he kept to his daily walks as well. And his lifelong motto, despite everything he faced in life, is kind of inspiring. We must be optimists. One must be an optimist. And you can argue, with his difficult decision starting in 1933, that his optimism may have betrayed him in that political circumstance. But I really appreciate your attention and coming out for this historical talk as a little change of pace. And if you have questions, I'd be happy to take a go at them. We're finishing ahead of time. We have plenty of time for questions. Can we go to that pivotal year of 1900, and can you say a little more about the Eureka moment where Planck quantizes radiant energy? You can probably say, oh, the mathematics of partitioning that energy forced the Planck. But can you say a little more qualitatively? Sure. He himself found the idea of quantum to be repugnant. Well, so these are just sort of minor, almost informal presentations at the Berlin Physics Society, both his October and December, as I understand it, 1900 contributions. So in October, he presents this new formula without much of a derivation. And by December, he works feverishly between. He has the right form in October. He's almost backed into it without much of a derivation. So he takes up Boltzmann's idea between October and December and leads to him saying, well, for some reason, we have to partition the energy when it communicates from matter to the ether. We don't have to take that partitioning anywhere else, but at least that juncture. But what he was excited about by December were the fitting constants that came out of it. So he gives a great estimate from that data fit of Boltzmann's constant, a great estimate of his new constant we call Planck's constant. And he started playing with these and deriving all kinds of other things, like Lohschmidt's number, the best estimate to date of Avogadro's number. So he's very excited about the numbers that come out and then forming really accurate universal units, just based on fundamental constants. So he's kind of off to the races about that and doesn't focus as much about some of the clumsy steps he had to make with combinatorics along the way. Indeed, he was very excited about what we now call Planck. Yes. We accept that. I do accept that. But what I would be interested in is if anywhere in the database can count the fact that these units are awfully high energy, awfully short distances, awfully short time periods. And the crisis of that for chemists, for physicists in the future, have you ever discussed that? That's a great question. And as far as I know, no. I have seen no discomfort with that. The further, I mean, Max Planck got to this point where the further it got away from human intuition, the happier he was. So it just seemed like part of the delight that those were such awkward numbers. And he took a lot of flack for these comments about extraterrestrials, or extraterrestrials, other cultures, and other galaxies would find these same units. And that makes them especially beautiful. Some of the positivists really took him to task over that. And he makes a little joke about it in his Columbia lectures, because Percival Lowell's work was such a hot topic at the time about Mars, and even mentions a little Martian quip in his Columbia lectures. But no, I haven't found a point where he expresses a worry about these scales. Yeah. Or just a discussion, too. No, I haven't. But it's just that you did not put him on the table. Yes, but I'll say, to be fair, I haven't gone categorically through some of his follow-up physics papers on the quantum theory. Definitely the second theory of quantization that he tries to derive, and things like this. Right. So then, like, in the 1930s, he was involved in that? Yeah, I say, definitely he was talking to people. Well, he was very excited from Schrodinger's wave mechanics. And Schrodinger was even, his heir apparent, was supposed to, Max Planck was finally going to retire, and Schrodinger was going to become the main theoretical physicist in Berlin. And very disturbed, then, by the Copenhagen interpretation. And there's letters back and forth with Einstein right away, like, well, this is crazy. This is a huge wrong step. And so in the book, I kind of say, Planck, really starting in the 19-teens, plays the part of kind of a worried parent, saying, be careful, as all these young guns are kind of running around with the quantum ideas. And so by the 20s, he's commenting on them. He's staying in touch, definitely attending meetings and colloquia, et cetera. But he's not contributing actively to the progress of the physics in those years. He's really starting more of his public outreach lecturing, and has some interviews on radio, and things like that. Other questions? OK, let's thank the speaker again. Thanks, everybody. Thank you.