Rebekka ‘Betty’ Aleida Biegel (1886-1943) was born into an intellectual Jewish family and studied astronomy in Leiden. She was the first assistant to astronomer Anton Pannekoek, discussed his theory of relativity with Albert Einstein and worked with psychology pioneer Carl Jung.
Because as a woman she could not get a permanent job in astronomy, she also studied psychology and founded the ‘psychotechnical’ laboratory of the PTT, the predecessor of KPN. There she was at the origin of psychological tests for aptitude for Morse code and driving skills. Betty Biegel is considered a pioneer of Dutch psychology.
But her Jewish origins proved fatal for her under the German occupation. She was arrested and in 1943 she committed suicide in camp Westerbork together with her sister Annie. Almost her entire family died.
“My family’s life has completely evaporated,” says Chris Verhoef, professor of computer science at the Vrije Universiteit Amsterdam and a distant relative of Biegel. She was the aunt of Verhoef’s mother. “There is nothing left of our family, except for a few people like me. But also no things, no photos, no albums, no papers, no letters, no pot, no pan.”
It was not until 1996 that a short biography of Betty Biegel was published by psychology historian Coen Rümke, based mainly on professional information and a few detailed photographs here and there. For example, Biegel is standing, laughing somewhat nervously, near a young Prince Bernhard, who visited the PTT laboratory in 1937.
But thanks to research by Verhoef and historian Jacques Dane, it has now become clear that Betty can also be seen in a famous photo from 1913 in Zurich, together with Albert Einstein, Paul Ehrenfest and other famous physicists. In the photo, in the archives of the ETH Zurich, where Einstein had an appointment, the participants of a colloquium, a scientific meeting, pose among the measuring beakers and other laboratory equipment. There is still some tea in a cup. The photo shows three women, but it was unclear who they were for a long time.
Facial recognition tools
Betty is the only woman in the front row, smiling affably at the camera, Verhoef and Dane argue in a forty-page article in the magazine Endeavourspecialized in the history of science. In it they mainly describe their search, in which unusual instruments were pulled out of the closet for historians: from AI facial recognition tools and network analyzes and computer scripts that rake together large quantities of handwritten minutes and make them searchable, to searches in illegal book collections on the Dark Web, and other OSINT techniques. OSINT stands for open source intelligenceintelligence work based on open sources. “I do forensic research, but I can never really say anything about that,” says computer scientist Verhoef mysteriously, “but for me those techniques were not that complicated.”
We speak to Verhoef together with Dane, in the basement of the Education Museum in Dordrecht, to which Dane is affiliated. “It actually started with a piece I wrote about an invention of Betty’s in the field of Morse code. Jacques, you said: a photo should actually be included.”
But then again, to pull out that unflattering photo with Prince Bernhard. Verhoef came across the Einstein photo from 1913 through a comment from a curator at the Boerhaave museum in Leiden, who said: “It is almost inevitable that Betty knew Lorentz.”
Nobel Prize winner Hendrik Antoon Lorentz (1853-1928) was the paternal center at the beginning of the last century, when Leiden University represented the absolute world top in physics research. He was a good friend of Einstein, who considered him his mentor, and brought the Austrian physicist Paul Ehrenfest to Leiden. Lorentz, quite emancipated for that time, also encouraged women to study physics and astronomy.
“I decided to make a network analysis of Betty’s acquaintances,” says Verhoef. This is a technique that maps contacts of a group of people. This was difficult for women at that time: although women obtained PhDs and participated in research, they were rarely given university positions, nor were they authorships of scientific publications.
Verhoef: “After just five minutes I came across this photo, which showed many people whom I knew Betty knew well, including two of her friends.” It helped that the American science historian Joanna Behrman in 2023 wrote a blog post about her search for the names of the women in the photo.
The two women in the back row, Behrman concluded, were not the Dutch high school teachers Van Leeuwen, as the original caption stated, but the Leiden mathematics and physics students Catherine Frankamp and Eva Bruins, who with Biegel were in the sorority VVSL. Behrman had her doubts about the identification of the lady in the front row, one AJ Grigorjeff.
An AI tool that compares faces gave a score of 78 percent between the lady in the front row and Biegel’s PTT photo from 1937, even though she was much older at the time. “With 80 percent you are usually talking about the same person,” says Verhoef. Another AI tool estimated her age in the Einstein photo at 27, which matches Biegel’s age when the photo was taken. A search for Grigorjeff, a Russian, through her family, turned up photos that looked nothing like the woman in the front row.
Postcard with 16 signatures
The next clue was a postcard that the participants of the colloquium sent to the Russian scientist Leonid Mandelstam, with 16 signatures. The original image of this postcard appeared to be found in a Russian book about Mandelstam’s life. The name ‘RA Biegel’ can be distinguished, not very clearly, at the bottom right.
Dane: “What is also clear from that postcard is that everyone who attended the colloquium had a function,” says Dane. “Those people were not just there. They were there because they could help Einstein prove ideas he had at the time.”
In 1913, Einstein struggled with his ideas about the general theory of relativity, which explains gravity as an effect of distortions of space and time. One of the predictions was that heavy masses, such as the Sun, could measurably bend the light of stars. This effect provided the first confirmation of Einstein’s predictions in 1919, when stars appeared to change places during a solar eclipse.
Many people are surprised when you say it, but Einstein could not calculate
But Einstein was far from that point in 1913. “Many people are surprised when you say it, but Einstein could not calculate,” says Verhoef. The German physicist had fantastic intuition and courage to try new ideas, but mathematics was not his strong point. Before that, he had colleagues and friends who he joked about Rechenpferde called math horses, after the then famous circus act of the calculating horse Hans.
Einstein used the colloquium as his sounding board. Paul Ehrenfest, second from the left, was his trusted sparring partner. And the Finn Gunnar Nordström, who is not in the photo but is on the postcard, was one of the first who could perform calculations with the difficult mathematics of Einstein’s theory.
Extensive star tables
“All three Dutch womenas Einstein called them in a letter, were great at performing astronomical calculations,” says Verhoef. “For example, Betty Biegel did her PhD on the star positions in Egyptian art: so she calculated the star positions in the sky back three thousand years. She could just do that.” In 1915 she also shared extensive star tables with the psychologist Carl Jung. Verhoef: “Of course we have no hard evidence that they made calculations for Einstein. But what were they doing there? If everyone had a position there.” Betty was, in short, one Rechenpferd.
In the wake of the search, three more photos emerged from the same June 30 in 1913. One of them also shows an unknown man. “We thought: who the hell is that?” Historians of science do not name the man. Here too, the computer methods provide new clues: the man turns out to be Hans Kern, an Austrian physicist who died in the First World War in 1915. Dane: “That explains why he completely disappeared from the radar after that.” Upon further searching, letters turned up in which Ehrenfest and Kern promised each other help in looking for academic positions, in which they addressed each other as “du”, something only close friends did.
Verhoef: “Then I went to the website of the Akademisches Gymnasium, where Ehrenfest was located. A disaster of a website, but if you search a little smartly you will find out that Kern was in his class. It was not known that they were close friends.” Kern’s Jewish family also largely died in the Second World War.
The research and comparison techniques that Verhoef and Dane have used can reveal more about the lives of people about whom little can be found in other ways, they argue. Because they were women, or because they were Jewish, or – as in Betty’s case – both.
Verhoef: “Annie and Betty’s end is described by Jacques Presser in the book The Night of the Girondins. One of the Biegels was a chemical engineer. He had made a supply of cyanide, and the whole family received the tablets. The Biegel sisters took them together when it became clear in Westerbork that they would be deported to Auschwitz.”
“This is about women’s history, and the history of marginalized groups, but for me personally it also applies: Betty now has a face. And that is really nice for the family, I notice that.”