Berta Karlik (1904–1990) was an Austrian physicist whose meticulous investigations into radioactive decay revealed that nature had been quietly producing element 85 – astatine – all along, a discovery with profound implications for contemporary cancer therapy. During an era when women were largely confined to unpaid laboratory roles, she became the first woman to hold a full professorship at the University of Vienna, breaking through institutional barriers whilst conducting groundbreaking research even during the isolation of World War II. Her life embodied a particular kind of scientific courage: not the dramatic bravery of public triumph, but the quiet persistence of a researcher who worked in Vienna’s margins, maintained rigorous standards when the world around her descended into chaos, and proved that discovery emerges not from access to prestige, but from rigorous thought and meticulous technique.
Berta, thank you for meeting with us today. We’re speaking in 2025 – thirty-five years after your death – and there’s been a remarkable resurgence of interest in your work, particularly among researchers studying astatine-211 for cancer treatment. Your natural astatine discovery is suddenly very relevant again. How does it feel to be remembered primarily through an element that people initially dismissed?
Well, I must say, it is rather gratifying. When Traude and I published our findings in 1942, there was considerable scepticism. The Americans had synthesised astatine artificially just two years earlier – Dale Corson and his colleagues at Berkeley – and the scientific community seemed satisfied with that achievement. The idea that nature had been producing it all along, quietly hiding in the uranium decay chains, was treated almost as a curiosity. It was not considered the “proper” way to discover an element.
But you see, that is precisely what made it interesting to us. The artificial synthesis proved that element 85 could exist, but our work answered a different question: does it? And if so, where, and in what quantities? These are the questions that matter for understanding the actual natural world, not merely what we can manufacture in the laboratory.
As for astatine-211 and cancer therapy – I confess I did not anticipate the specific medical applications, though I suspected the element’s properties might prove useful. We were simply following the science where it led.
Let’s go back to the beginning. You grew up in Vienna’s upper-class circles in the early 1900s. How did you, the daughter of a prominent family, end up in a laboratory studying radioactive decay?
It was not an obvious path, I admit. My childhood was quite sheltered. Piano lessons, languages – I was fluent in German, French, English, and Italian before I was twelve – and home tutoring in the classical subjects. My parents were cultured, well-connected people. Neither was a scientist, though they were both intellectually curious. When I was nineteen, I was finally permitted to attend the Reform-Realgymnasium, which was quite progressive for Vienna at that time. It was an all-girls institution, which meant we were neither coddled nor treated as oddities for our academic pursuits.
My real awakening came through reading. I became fascinated with the periodic table – with the architecture of the elements – and this led me to Mendeleev, then to the radioactive discoveries of Curie and Rutherford. There was something compelling about the notion that matter was not inert and fixed, but dynamic, transformative. I think I was drawn to physics because it asked what lay beneath the visible world.
My father was tolerant of my intellectual interests, though he seemed to expect I would eventually marry a professor and abandon the pretence of a scientific career. pauses In that, at least, he was partially correct. I married twice – both to physicists – but I did not abandon the work. That was where we differed.
You earned your doctorate in 1928 from the University of Vienna, working under Hans Pettersson at the Radium Institute. What was that experience like?
Extraordinary. Pettersson was a rigorous experimentalist – Swedish, with exacting standards. He took me on as a graduate assistant, which was unusual but not unheard of. The Radium Institute was one of the few places in Vienna where a young woman could pursue serious physics work, partly because it was still somewhat underfunded, understaffed, and regarded as a secondary field compared to theoretical physics.
The work centred on scintillation counters – do you know what these are? They are elegant instruments. You see, when alpha particles or beta particles strike certain crystals – zinc sulphide was our preference – they produce tiny flashes of light. The human eye can observe these scintillations, and by counting them, one measures the rate of radioactive decay. Pettersson was developing more sensitive counting techniques, and I became quite proficient at the instrumentation.
It was meticulous work. Extraordinarily meticulous. You had to account for background radiation, maintain optimal humidity in the counting chamber, adjust the brightness of the observation chamber precisely so the flashes were visible but the eye was not strained. People often imagine scientific discovery as something sudden – a eureka moment – but much of my work involved perfecting these incremental improvements in measurement, learning to read the data more accurately than anyone before.
After your doctorate, you had a remarkable opportunity – you worked with William Henry Bragg in London in 1930. Bragg was already a legend. What drew you to crystallography?
Bragg was indeed a legend, and I was terrified when I arrived at his laboratory. laughs Here I was, a young Viennese woman, and I was to work alongside some of the finest crystallographers in the world.
What drew me was the elegance of the method. X-ray diffraction – the use of X-rays to determine crystal structure – is fundamentally about deciphering a code. You bombard a crystal with X-rays, the atoms scatter the radiation in very precise patterns, and from those patterns, you can reconstruct the three-dimensional arrangement of the atoms themselves. It is like being given a photograph of light interference and being asked to deduce the architecture of matter.
Bragg’s laboratory was rigorous but also generously intellectual. Unlike some senior scientists, he did not regard women researchers as temporary visitors to be tolerated. He treated us as collaborators. I learned an enormous amount about precision measurement, about the importance of controlling variables, and about the psychology of being wrong – which happens frequently in experimental work, and which must be treated not as shame but as information.
That year in London also gave me something else: an international network. I met Ellen Gleditsch, a Norwegian physicist of remarkable accomplishment, and through the scientific community in London, I encountered the work of women doing physics across Europe. This was crucial for me. It established that a woman could be a rigorous, productive physicist, not as an exception, but as a normal state of affairs.
And then you visited Marie Curie’s laboratory in Paris?
Yes, briefly. Madame Curie was elderly by then, but her laboratory retained an extraordinary spirit. It was a place where women worked as scientists, not as assistants to male scientists. I spent time there learning about their work on polonium and their isotope separation techniques. More than anything, it reinforced the notion that women could establish institutions, train younger researchers, and create environments where rigorous science was simply science, regardless of the sex of the person conducting it.
After my time in London and Paris, returning to Vienna felt somewhat provincial. But I returned nonetheless. The Radium Institute was my home institution, and there was important work to be done.
Let’s talk about your network of female physicists. You corresponded regularly with Lise Meitner, Ellen Gleditsch, and others. How important was that network to your career, especially as the 1930s became increasingly difficult?
It was essential. And I say that without any sentimentality. Science is often portrayed as an individualised intellectual pursuit, but it is far more social than that. We shared preprints before formal publication. We discussed theoretical interpretations in letters. We warned each other about difficulties in various laboratories and offered advice about navigating institutional politics.
Lise Meitner became a particularly close correspondent. We discussed her work on uranium fission, of course, but we also discussed the practical challenges we faced as women in physics during those years. Lise left Germany in 1938 – you must understand, the political situation was becoming untenable for Jewish scientists. She eventually reached Sweden. Ellen Gleditsch was working in Oslo. I remained in Vienna.
This network allowed us to remain intellectually current even as we were geographically isolated from the major centres of physics. And as the war approached, it became something else: it was a form of resistance, a maintenance of international scientific community at precisely the moment when nationalism and ideology threatened to obliterate it.
I was fortunate that this network existed. Without it, I may well have become entirely cut off.
The war years must have been extraordinarily difficult. Austria was annexed into the Third Reich in 1938, and Vienna became, essentially, a captured city. How did you continue your work?
With difficulty. The institute became increasingly constrained. Funding diminished. Equipment was diverted to military applications. Many of my colleagues left – those who could leave, those for whom it was necessary to leave. I remained. It is a decision I have been questioned about, both at the time and since, and I do not entirely know how to defend it.
What I can say is that I believed there was still work worth doing, and that maintaining rigorous science during a period of collective madness was, in its own way, a form of moral commitment. The Nazis had certain attitudes towards physics – they dismissed relativity as “Jewish science,” they valued applied research over pure investigation – but they did not entirely dismantle research institutions. There was still a laboratory. There were still materials. There were still questions to investigate.
Traude Bernert and I began our intensive investigation of the uranium decay chains around 1941 or 1942. We were looking for evidence of transuranic elements – elements heavier than uranium. The Berkeley group had announced the synthesis of element 85 in 1940, and we wondered: might this element exist naturally?
This is where we should really explore your most significant work. Walk us through the astatine discovery. How did you approach the problem, what methods did you use, and what made you confident that you had found something real?
Very well. First, understand that element 85 was purely theoretical until Corson, MacKenzie, and Segrè created it by bombarding bismuth with accelerated alpha particles. They produced astatine-211, a radioactive isotope with a half-life of about 7.2 hours. The question we posed was: if this element can be made, might it occur naturally through the radioactive decay of heavy elements?
The answer required us to understand decay chains. Uranium-238, for instance, does not decay directly to lead. Instead, it undergoes a series of transformations – alpha decay, beta decay, alpha decay again – a cascade that passes through various intermediate elements. We knew the uranium decay chain reasonably well. The question was whether one of the intermediate steps might produce astatine.
Our approach was this: we obtained materials enriched in uranium – specifically, we worked with uranium ores and with pitchblende, which contains both uranium and its decay products in secular equilibrium, meaning the radioactivity is in a stable ratio reflecting their half-lives.
We used fractional crystallisation to separate the elements according to their chemical properties. Astatine is a halogen, so we exploited that chemical nature to concentrate it. We then used spectrographic techniques to identify the presence of the element through its characteristic radiation signature. This involved scintillation counting with exceptional precision.
The critical measurement was this: we detected alpha particles with energies consistent with the decay of astatine-211. More precisely, we measured an alpha-particle energy of 7.0 megaelectronvolts, which matched theoretical predictions for the decay of astatine-211 to bismuth-207. We could quantify the activity – the number of decays per unit time – and from this, we could calculate the abundance of astatine in the ore.
What made us confident was reproducibility. We repeated the measurements with different ore samples. We varied our extraction methods. We obtained consistent results. And – this is crucial – the abundance we found was not random. It fell within the range predicted by theoretical calculations about decay chain equilibrium.
We published our results in 1942 in a German-language journal. The paper was titled, if I recall correctly, “On the natural occurrence of element 85” or something quite similar. We documented everything: the methods, the measurements, the error margins, the calculations.
The error margins – what were they? And how did you account for background radiation, which must have been a significant challenge?
Excellent question. Background radiation was indeed the critical challenge. In Vienna, we did not have access to underground laboratories, which shield one from cosmic radiation. We had to work in standard laboratory conditions, which meant constant low-level background radiation from natural sources – radon, cosmic rays, terrestrial radioactivity in the building materials.
We controlled for this in several ways. First, we conducted measurements on identical samples of material known to be free of astatine. These blank samples gave us the baseline background rate. Second, we shielded our detection apparatus using lead and other heavy materials to reduce cosmic and external gamma radiation. The scintillation counter itself was housed in a well of lead perhaps ten centimetres thick.
As for error margins, we worked with alpha-particle spectra showing distinct energy peaks. The astatine-211 peak appeared at 7.0 MeV and was separated from other peaks by sufficient energy gaps that we could distinguish it with reasonable confidence. I would estimate our uncertainty at approximately ±15 to 20 per cent for the activity measurements. Not exceptional by modern standards, but quite respectable for the time, particularly given wartime constraints on equipment and materials.
Traude was meticulous about statistical analysis. We did not simply count scintillations; we accumulated counts over many hours and applied statistical methods to estimate the true rate and the confidence intervals. This was before computers, of course. We did the calculations by hand, using logarithm tables and mechanical calculators.
The procedure was: we would prepare a sample, run the measurement apparatus for perhaps ten to twenty hours, record the data – literally making pencil marks on paper or in notebooks – then spend several days performing the calculations to extract the decay rate and energy values.
Given that the Berkeley group had synthesised astatine artificially in 1940, and they were working with far superior funding and equipment, why was your demonstration of its natural occurrence important? Couldn’t they simply have looked for it themselves?
That is a fair question, and it captures a genuine historical puzzle. The Berkeley physicists proved that astatine could exist and could be made. They did not necessarily have reason to believe it occurred naturally. And here is the thing: the United States during the war was entirely focused on the Manhattan Project – the development of nuclear weapons. The resources, the ambition, the talented physicists – all were directed toward that enormous effort. Scientific curiosity about whether element 85 occurs in nature was not a priority.
Moreover, searching for a rare element in natural materials requires a different experimental strategy than synthesising it. It requires sensitivity to extremely low abundance levels, understanding of natural decay chains, and patience to accumulate data over extended periods. The Americans had the equipment, certainly, but their institutional focus was elsewhere.
Our contribution was to answer a fundamental question about the natural world that the artificial synthesis had left open. We proved that the periodic table is not merely a cabinet of synthetic achievements but reflects actual processes occurring in nature. This is not trivial. It means that all the heavy elements do not require human intervention to exist – they are produced by nature through the transmutation of uranium.
This has implications for cosmic chemistry, for understanding the abundances of elements in the earth’s crust, for understanding how heavy elements are created. It is a different sort of discovery than synthesis.
As for why it was not pursued vigorously by others, I suspect several factors: the war, the dominance of Anglo-American physics centres with different research priorities, and, if I am being candid, a certain dismissal of work conducted in Vienna by a woman and her colleague during wartime. Our findings were published in German in a journal that was not widely circulated internationally after the war began. This contributed to the invisibility of the discovery.
That’s a sobering assessment of how geography and institutional power affected scientific credit. But after the war, once Vienna was liberated and international contact resumed, did the scientific community recognise your work?
There was recognition, yes, but of a peculiar sort. I was awarded the Haitinger Prize for Chemistry from the Austrian Academy of Sciences in 1947 – that was genuine recognition, and I was grateful for it. But in the broader international literature, the astatine discovery continued to be attributed primarily to Corson, MacKenzie, and Segrè. Our demonstration of natural occurrence was mentioned, if at all, as a footnote to their achievement.
This is a pattern, I have observed, in how scientific credit is allocated. The dramatic, first achievement – the laboratory synthesis – receives the primary recognition. The subsequent proof of natural occurrence, which required different ingenuity and which answered different questions, is regarded as secondary confirmation.
I do not blame Corson and his colleagues. They conducted excellent work. But I notice that no one questions whether Corson deserves credit for proving astatine exists artificially. Yet many people questioned whether Traude and I deserved credit for proving it exists naturally. The asymmetry is worth noting.
You became director of the Institut für Radiumforschung in 1947, and then in 1956, you were appointed as the first woman to hold a full professorship – an ordentliche Professur – at the University of Vienna. That institution is over 650 years old. How did that appointment come about?
It was complicated. By the late 1940s and early 1950s, I had published extensively, trained younger researchers, and directed the institute through its post-war reconstruction. The university was, at last, considering expanding its faculty in the sciences. There was pressure from certain quarters to recognise the contributions of senior women researchers.
I should be honest: I had supporters – colleagues who valued my work and who believed the university’s reputation was damaged by not formally recognising women scientists at senior levels. I also had critics who believed that giving me an Ordentliche Professur would lower the prestige of the title. These were not private opinions; they were stated quite openly.
The position was justified, I believe, on the basis of my research record, my administrative leadership of the institute, and my international reputation. But I am certain that my sex was simultaneously an asset and a liability. It was an asset because it allowed the university to make a progressive statement about its commitment to women in science. It was a liability because some saw my appointment as tokenism.
I have tried not to worry overmuch about these interpretations. I did the work. I earned the rank. That should be sufficient.
But it wasn’t simple, was it? Being the first woman in a certain position is never simple.
No. It is not. You carry a kind of representative weight that your male colleagues do not experience. Decisions you make are interpreted as statements about whether women “should” be in such positions. Your failures are taken as evidence that women are unsuitable. Your successes are attributed to exceptional talent or special circumstances rather than to normal competence.
I was conscious of this burden. It made me more careful in some ways – I would not tolerate sloppy work from myself or my laboratory – but it also made me somewhat rigid. I sometimes wonder if I was too exacting as a supervisor, too unwilling to accept small imperfections that might have been acceptable in another director. I was not simply managing a laboratory; I was managing the perception of women in science.
That is unfair in some ways – the burden itself is unfair – but it is the reality one faced.
Let’s talk about your approach to science. What did you value most in your work?
Precision. Clarity. Intellectual honesty. These were not sentimental values for me; they were practical necessities. If you are measuring radioactive decay and your measurements are imprecise, you cannot draw reliable conclusions. If you are unclear in your experimental design, you cannot reproduce your results. If you are dishonest about your findings or about the limitations of your data, you undermine the entire enterprise of science.
I also valued elegance in experimental design. By elegance, I mean economy – achieving precision and clarity with minimal complexity. The scintillation counter is an elegant instrument because it converts an invisible phenomenon – radioactive decay – into a visible, countable signal using beautifully simple principles. X-ray crystallography is elegant because it allows you to infer three-dimensional structure from two-dimensional diffraction patterns. These are not merely technically impressive; they are intellectually elegant.
And I believed strongly in the social nature of science. Science requires conversation, collaboration, criticism. My network of female colleagues was not peripheral to my work; it was central to it. We challenged each other’s assumptions, we shared techniques, we maintained standards collectively. The notion that a scientist works in isolation and makes discoveries through solitary genius is largely mythology.
You mentioned intellectual honesty. Have there been moments when you discovered you were wrong about something important?
Many moments. Let me give you a specific example. Early in my work on uranium decay chains, I made an error – a significant one – in my theoretical calculations about the expected abundance of astatine. I had underestimated it. When our experimental measurements came in higher than I had predicted, I was initially suspicious of the data. I thought there must be contamination, or a systematic error in the apparatus.
It took me several weeks and considerable frustration to accept that my theoretical prediction was simply wrong. My understanding of decay chain equilibrium was incomplete. Once I accepted that, I could recalculate and understand why the experimental value made sense. But those weeks of fighting against the evidence were wasteful and frustrating.
The lesson I took from that experience – and there have been others like it – is that as a scientist, one’s intellectual investment in a particular theory or calculation is a liability. You must be willing to discard ideas that the evidence contradicts, even if you invested considerable thought in them.
I was also wrong, I should say, in my earlier years about certain institutional politics. I underestimated how much resistance there would be to my career advancement, and I overestimated how much good research alone would overcome. I thought if one simply did excellent work, one would be recognised and advanced. I learned that excellent work is necessary but not sufficient. One must also navigate institutional dynamics, build alliances, and sometimes fight for recognition that should have been automatic.
You continued working at the institute well into your eighties. Why?
Where else would I go? Science was not something I did; it was something I was. The laboratory was home to me, perhaps more genuinely than the flat where I lived. And there was always more work – new graduate students to train, new questions emerging from our previous results, new techniques to master.
In the later years, I was less focused on making new discoveries and more focused on clarifying and publishing the work we had done, on training the next generation, on ensuring that the standards and methods we had developed were preserved and transmitted. That was its own form of scientific work.
How do you feel about the current applications of your work in cancer treatment? Astatine-211 targeted alpha therapy is in clinical trials now.
This genuinely moves me. When Traude and I were measuring alpha particles in Vienna during wartime, we had no idea that these particles – products of radioactive decay – would one day be weaponised, in a sense, against malignant cells. The therapeutic application is extraordinarily elegant: you attach astatine-211 to an antibody that specifically recognises cancer cells. The antibody delivers the astatine directly to the tumour. The alpha particles then destroy the cancer cells from within, with minimal damage to surrounding healthy tissue.
It is a marriage of chemistry, biology, and physics. Our discovery of natural astatine provided the foundation for understanding its nuclear properties. The fundamental physics remains: the same decay process we measured in the 1940s is now being harnessed for healing.
Of course, it would be more satisfying if this application had been recognised decades earlier, if our work had received fuller credit and if the connection between our discovery and modern medicine had been made explicit. But that is a rather churlish attitude. The important thing is that the science serves humanity. That remains true whether or not my name is prominently associated with it.
What advice would you offer to women entering physics today? Or to scientists from marginalised groups who face barriers similar to those you encountered?
First: do not make your work secondary to any approval seeking. Do the science because the science matters, not because you hope to earn recognition. Recognition may or may not come, and if it does not, you will at least have done something worth doing.
Second: build networks with other people in your position. Do not compete destructively with them. Collaborate. Share information. Warn each other about pitfalls. Support each other’s work publicly and privately. This was my salvation during the war years and after.
Third: become genuinely expert at something. Not competent – expert. Deep, genuine mastery of your field makes you harder to dismiss or marginalise. Mediocrity is easily overlooked; excellence is harder to ignore.
Fourth: do not accept the premise that you must be exceptional to deserve a seat at the table. You should demand ordinaries – the right to be a normal, flawed, developing scientist without that flawedness being attributed to your identity.
And finally: remember that the barriers you face are not your fault, but overcoming them is partly your responsibility. This is paradoxical, I know, but I mean it this way: the institutional barriers are real and structural; they are not failures on your part. But you cannot simply wait for institutions to change. You must be both rigorous enough and strategic enough to create space for yourself and for others.
It is tiring. It is unfair that it should be necessary. But it is the reality, and ignoring it serves no one.
Last question. How would you like to be remembered?
As a scientist who did good work. Not as the first woman to do something – though I am grateful that I was able to be that, and I hope it helped make space for others. Not as a victim of circumstances – I had agency, I made choices, I navigated with some skill. But simply as a physicist who took precision seriously, who asked good questions, and who contributed something meaningful to human understanding of the natural world.
The element astatine will outlast me. The methods we developed for measuring radioactive materials will be refined and superseded. My career will eventually fade into historical footnotes. That is as it should be. But the work will remain, woven into the fabric of science. That is enough. That is more than enough.
Thank you, Berta. This has been a remarkable conversation.
The pleasure was mine. And thank you for remembering.
Letters and emails
Since the publication of this interview, we’ve received correspondence from researchers, historians, and scientists across the globe eager to extend the conversation with Berta Karlik. What follows are five letters and emails selected from our growing community – each reflecting genuine curiosity about her methods, her choices, and the lessons her experience might offer to those pursuing similar paths in science today.
These questions venture into territory the initial interview only touched upon: the technical reasoning behind her experimental choices, the ethical dimensions of mentoring and institutional leadership, the cognitive experience of moving between different scientific disciplines, the pragmatic tension between fundamental curiosity and applied discovery, and the counterfactual question of how history might have unfolded differently.
Collectively, they illuminate what it means to sustain rigorous science under constraint, to build international networks that transcend geography and circumstance, and to recognise that the most enduring discoveries often emerge not from access to resources, but from intellectual clarity and genuine engagement with difficult problems.
Farah Siddiqui (32, Radiochemist and Environmental Scientist, Dhaka, Asia)
You mentioned combining oceanography with radiophysics to study uranium content in seawater – a field that’s become urgent again with climate change and nuclear waste concerns. When you were developing those methods in the 1930s and 1940s, how did you decide which detection techniques to prioritise when measuring such dilute concentrations? Were there competing approaches you rejected, and if so, what made scintillation counting the better choice over, say, electrochemical methods or early mass spectrometry? I’m asking because modern environmental radioactivity work faces similar trade-offs between sensitivity, specificity, and cost, and I wonder whether your early reasoning still applies or whether new technology has fundamentally changed the problem.
Ah, now this is a question that takes me back to some of the most challenging work we undertook. The uranium content of seawater – this was research Hans Pettersson initiated in the early 1930s, and I was deeply involved in refining the methods. You are quite right to identify it as a forerunner to contemporary environmental radioactivity concerns, though at the time, we were motivated primarily by fundamental geochemical questions: How much uranium exists in the oceans? What are the mechanisms of its distribution? These questions had implications for understanding the age of the Earth and the origins of radioactive elements in marine sediments.
The technical challenge was formidable. Uranium concentrations in seawater are extraordinarily low – on the order of parts per billion, perhaps three micrograms per litre. At such dilutions, direct measurement was essentially impossible with the equipment available in the 1930s. We had to develop concentration techniques first, then apply detection methods to the concentrated samples.
Why scintillation counting rather than electrochemical methods or mass spectrometry? Let me explain the reasoning, because it was not immediately obvious, and we did consider alternatives.
Electrochemical methods – particularly polarography, which Jaroslav Heyrovský was developing in Prague around that time – offered certain advantages. They could detect metal ions at low concentrations through their characteristic reduction potentials. However, seawater is a complex matrix. It contains sodium, magnesium, calcium, chlorides, sulphates – a veritable soup of interfering ions. Separating uranium electrochemically from this background would have required extensive chemical purification beforehand. Moreover, electrochemical methods measure concentration, not radioactivity. They do not distinguish between uranium isotopes, which was crucial for our work, because we were interested in the decay properties of uranium-238 and uranium-235.
Mass spectrometry – well, this was still in its infancy. Francis Aston had developed his mass spectrograph in the 1920s, and it was a magnificent instrument for separating isotopes. But it required vaporising the sample, ionising it, and accelerating the ions through magnetic fields. The equipment was extraordinarily expensive, extraordinarily delicate, and extraordinarily rare. There were perhaps half a dozen institutions in the world with functioning mass spectrographs, and none of them were readily available for routine seawater analysis. We simply did not have access.
Scintillation counting, by contrast, exploited the radioactivity itself. Uranium and its decay products emit alpha particles. When these alpha particles strike zinc sulphide crystals, they produce visible flashes – scintillations. The method is elegant because it is direct: you are observing the decay process itself, not an indirect chemical property. And because alpha particles are highly energetic and relatively rare compared to beta or gamma radiation from other natural sources, the signal-to-noise ratio can be quite favourable if one is careful about sample preparation.
The procedure we developed was this: we would take large volumes of seawater – sometimes hundreds of litres – and concentrate the uranium through chemical precipitation. We added ferric hydroxide, which co-precipitates uranium from solution. This gave us a solid precipitate enriched in uranium by perhaps a factor of ten thousand or more. We then dissolved this precipitate, further purified it using solvent extraction with ether – uranium forms complexes with nitrate that are soluble in organic solvents – and finally deposited a thin layer onto a glass slide or metal disk.
This prepared sample was then placed in the scintillation chamber. We used a microscope fitted with a zinc sulphide screen, and we would sit in a darkened room, counting the flashes by eye. It was tedious work. One’s eyes had to be dark-adapted for at least twenty minutes before beginning, and even then, counting required intense concentration. A typical measurement might involve counting scintillations for thirty minutes to an hour, tallying them on a mechanical counter, then repeating the measurement to ensure reproducibility.
The advantage of this method was its specificity and sensitivity. Alpha particles from uranium decay have characteristic energies – roughly 4 to 5 megaelectronvolts – and they produce distinct, bright scintillations. Background counts from cosmic radiation or other sources were relatively low if the apparatus was properly shielded and the chemicals were pure. We could detect uranium concentrations well below one microgram per litre, which was sufficient for seawater measurements.
Now, you ask whether the reasoning still applies in your contemporary work, or whether new technology has fundamentally changed the problem. I would say this: the principles remain the same, but the techniques have been refined beyond recognition. You have access to liquid scintillation counters, semiconductor detectors, inductively coupled plasma mass spectrometry – tools that would have seemed like science fiction to us. These instruments automate what we did manually, with far greater precision and far less labour.
But the fundamental trade-offs you mention – sensitivity, specificity, cost – these persist. Scintillation counting was chosen because it offered the best balance for our circumstances: sufficient sensitivity, direct measurement of radioactivity, and feasible cost. If you are measuring environmental radioactivity today, you must still make similar judgements. Do you need isotope-specific information, or is total activity sufficient? Can you afford the expensive instrumentation, or must you work within budget constraints? How pure are your reagents, and how much sample preparation can you realistically perform?
The other lesson, perhaps less obvious, is this: environmental radioactivity work requires patience and rigorous attention to chemical purity. In seawater analysis, contamination from laboratory glassware, reagents, or even atmospheric dust can introduce errors larger than the signal you are trying to measure. We learned to use only the purest acids, to clean all glassware with acid washes, and to work in conditions as dust-free as possible. These practices – what you would now call quality assurance – were not formalised in the 1930s, but we developed them through trial and error, through failed measurements and puzzling inconsistencies.
So yes, I believe the early reasoning still applies. The technology has advanced, but the intellectual framework – identifying the signal, minimising background, validating through reproducibility – remains constant. That is the beauty of experimental science: the methods evolve, but the principles endure.
Julián Santander (51, Physicist and Science Policy Advisor, Buenos Aires, South America)
Imagine Austria had remained neutral during World War II, or imagine you’d accepted an offer to emigrate – say, to the United States or Sweden – in 1938 or 1939. Would your discovery of natural astatine have happened at all? Would it have happened sooner, with better resources? Or would you have been absorbed into the Manhattan Project like so many other physicists? I ask because your wartime work in Vienna feels almost accidental – you were isolated, yet that isolation created the conditions for rigorous, focused research. It makes me wonder whether access to resources and prestige actually enables discovery, or whether sometimes the constraints force the ingenuity that leads somewhere genuinely new.
This is a question I have asked myself many times, particularly in the years after the war when I learned what had become of certain colleagues who did emigrate. The counterfactual – what if I had left – haunts me in ways both intellectual and personal.
Let me address the practical matter first: would the discovery of natural astatine have happened if I had emigrated? Almost certainly not. Not by me, at any rate, and possibly not by anyone for many years. The reason is straightforward: had I gone to the United States or Britain in 1938 or 1939, I would have been absorbed into war-related research. There is no question of this. Every physicist of any competence was recruited. Lise Meitner, who escaped to Sweden, found herself working on reactor physics. Those who went to America – well, we know what happened there. Los Alamos. The Manhattan Project. The development of nuclear weapons.
I would not have been a central figure in such work – I was not a theorist, and the Americans had no shortage of experimentalists – but I would have been assigned to some aspect of uranium enrichment, plutonium separation, or neutron cross-section measurements. Useful work, certainly, but entirely directed toward military applications. The question of whether astatine occurs naturally in decay chains would have been irrelevant to the war effort. No one would have given me time or resources to pursue it.
So the isolation of wartime Vienna, paradoxically, created the conditions for discovery. We were cut off from the major centres of physics, yes, but we were also left alone to pursue fundamental questions that had no immediate practical application. The Institut für Radiumforschung continued to function – diminished, understaffed, but functioning. We had access to uranium ores through historical relationships with mining operations in Joachimsthal, in what was then the Sudetenland. We had the equipment, the knowledge, and most importantly, the time to conduct painstaking measurements over months and years.
Traude Bernert and I worked in relative obscurity. No one was directing us to abandon pure research in favour of applied problems. No one was monitoring our work for military relevance. We were simply two physicists investigating radioactive decay chains because that is what interested us and because the question was scientifically important.
Now, you ask whether the discovery would have happened sooner with better resources. This is more complicated. Better resources – more sensitive detectors, purer chemical reagents, larger quantities of uranium ore – would certainly have accelerated certain aspects of the work. But I am not convinced it would have been fundamentally faster. The challenge was not primarily technical; it was conceptual. We had to recognise that element 85 could occur naturally, that it was worth searching for, and that the abundance would be extraordinarily low – perhaps one part in 10^17 or 10^18 relative to uranium. That required patience, careful reasoning about decay chain branching ratios, and a willingness to pursue a result that might not exist.
In a well-funded laboratory in America or Britain, surrounded by other pressing problems and competing priorities, would anyone have devoted months to such a speculative search? I doubt it. The culture of wartime physics was one of urgency, of measurable progress toward defined goals. Our work was the opposite: slow, exploratory, uncertain.
As for whether I would have emigrated if Austria had remained neutral – this is the more painful counterfactual. If there had been no Anschluss, no Nazi occupation, then the question of leaving would not have arisen in the same urgent form. I might have continued my career in Vienna without interruption, maintaining international collaborations, attending conferences, publishing in widely circulated journals. In such a world, the discovery might still have happened, perhaps even more quickly, because I would have had better access to the international literature and to discussions with colleagues working on related problems.
But Austria did not remain neutral. And I did not emigrate. Why? The reasons are multiple and not entirely rational. Partly, it was attachment to place – to Vienna, to the institute, to the laboratory that had been my intellectual home for nearly two decades. Partly, it was a sense of obligation to younger researchers and to the institution itself. If all the senior scientists left, what would remain? Partly, it was a failure of imagination. In 1938, I did not fully comprehend what was coming. I thought it might be temporary, that the political situation would stabilise, that one could simply keep one’s head down and continue working. This was naive, but it was a common enough delusion at the time.
And partly – I must be honest about this – it was because I was not Jewish, and therefore not in immediate danger. Had I been in Lise Meitner’s position, I would have left. One does not stay in a place where one’s life is threatened. But I was not threatened in that way, and so I stayed. This is not something I am particularly proud of, but it is the truth.
You suggest that constraints force ingenuity that leads somewhere genuinely new. I think there is truth in this, though it is an uncomfortable truth. The isolation of wartime Vienna forced me to work with limited resources, to be extraordinarily careful with materials, to think deeply rather than simply throwing equipment at a problem. The scarcity created a certain intellectual discipline.
But I would not romanticise it. Constraint is not inherently productive. For every discovery made under difficult circumstances, there are a dozen that were delayed or never happened because the resources simply were not available. I was fortunate that the particular problem I was working on – natural astatine – could be addressed with the tools at hand. Had I been working on high-energy particle physics or nuclear reactor design, the isolation would have been crippling.
And there is another consideration: the human cost. Working in wartime Vienna was isolating not merely in terms of access to equipment, but in terms of intellectual community. I did not know what colleagues abroad were discovering. I could not attend conferences. Letters were censored or lost. The loneliness of that period was profound. After the war, when international contact resumed and I learned what had been accomplished elsewhere, there was a sense of having been left behind, of having missed crucial developments.
So to answer your question directly: I believe the discovery of natural astatine was a product of wartime isolation – it happened because of the constraints, not despite them. But I do not think this generalises into a principle that scarcity always breeds innovation. Sometimes it does. More often, it simply breeds frustration and wasted potential.
If I could rewrite history, would I have emigrated? I genuinely do not know. The version of myself who stayed made a discovery of lasting importance. The version who left might have contributed to the war effort, might have built a different career in a different country, might have remained in closer contact with the scientific community. Both paths have their merits and their costs. I can only speak for the path I actually walked, and say that it led somewhere worth going, even if the journey was difficult and lonely.
Ana-Maria Ionescu (45, Historian of Science and Gender Studies, Vienna, Europe)
In the interview, you spoke about the burden of being a “first” and how it shaped your laboratory management style – perhaps making you overly exacting. But I’m curious about something you didn’t expand upon: did you deliberately mentor women differently than men in your laboratory? And if so, was that a conscious strategy to prepare them for the same structural barriers you faced, or did you worry it might reinforce the idea that women needed special treatment to succeed? I ask because contemporary research on mentorship shows that the most effective support often comes from acknowledging rather than obscuring these differences.
This is a difficult question to answer with complete honesty, because it requires me to examine decisions I made instinctively rather than through deliberate policy. But yes, I did mentor women differently than men in my laboratory. Whether this was conscious strategy or unconscious bias – or some mixture of both – I cannot entirely say.
Let me begin with what I observed. When I became director of the Institut für Radiumforschung in 1947, I inherited a laboratory that had been traditionally male-dominated, though women had always worked there – usually in subordinate positions, as assistants or technicians. After the war, there were more women entering physics as doctoral candidates and postdoctoral researchers. Some came to me specifically because I was a woman in a senior position. They assumed, I think, that I would be more sympathetic to their circumstances.
I was sympathetic, but I was also acutely aware of the dangers. If women trained in my laboratory were perceived as receiving preferential treatment or as being held to lower standards, it would damage not only their careers but mine as well, and by extension, the prospects of all women physicists. The institution was watching. My male colleagues – some supportive, some sceptical – were evaluating whether a woman could direct a serious research institute. Any hint that I favoured women or that I lowered expectations would have been seized upon as evidence that women lacked the rigour necessary for leadership.
So I made a decision, perhaps instinctively: I would hold women to higher standards than men. Not formally – I could not do that explicitly – but in practice. I demanded more thorough documentation, more careful error analysis, more rigorous experimental controls. When a woman made a mistake in the laboratory, I corrected it immediately and firmly. When a man made the same mistake, I was more likely to let it pass or to address it more gently.
This was not fair. I knew it at the time, though I did not articulate it in quite these terms. I rationalised it by telling myself that I was preparing women for the hostile world they would encounter once they left my laboratory. If they could meet my exacting standards, they could meet anyone’s. If they developed habits of extraordinary thoroughness, they would be better equipped to defend their work against the inevitable questioning and scepticism.
But there was another dimension to this, which I recognised only later. I also gave women more latitude in certain ways. I allowed them to pursue questions that were somewhat tangential to the main research programme if they showed genuine intellectual curiosity. I encouraged them to present their work at seminars, even when they were junior researchers. I wrote letters of recommendation that emphasised not only their technical competence but their independence and creativity – qualities that male referees often neglected to mention for women candidates.
And I spoke to them privately about the structural barriers they would face. I did not do this with male students, because they did not need to hear it. But with women, I was candid. I told them that their work would be scrutinised more carefully than that of their male peers. I told them that they would need to publish more, to be more rigorous, to avoid even the appearance of error. I told them that collaboration with men could lead to their contributions being minimised or attributed to their male colleagues. I advised them to keep meticulous records, to insist on proper authorship credit, to document their intellectual contributions in writing.
Was this reinforcing the idea that women needed special treatment? Perhaps. But I believed – and I still believe – that acknowledging structural barriers is not the same as accepting them. If you pretend the barriers do not exist, you send young women into the world unprepared. They will encounter discrimination, and if they have not been warned, they may internalise it as personal failure rather than recognising it as institutional bias.
I will give you a specific example. In the early 1950s, I had two doctoral students working on related projects involving alpha-particle spectroscopy. One was a young man, the other a young woman. Both were competent. Both made progress. When they presented their preliminary results at a laboratory meeting, the young man’s work was received with polite interest and minor technical questions. The young woman’s work was subjected to extensive questioning about her calibration procedures, her statistical methods, her interpretation of the data.
After the meeting, I took the young woman aside. I told her that her work was sound, that the questioning had been more intense not because her methods were deficient but because she was a woman and the audience was looking for flaws. I advised her to prepare even more thorough documentation for future presentations, to anticipate every possible objection, to leave no room for doubt.
She was angry – not at me, but at the situation. She asked, quite reasonably, why she should have to work twice as hard to receive half the credit. I had no good answer except to say that this was the reality, and that we could either rail against it or prepare ourselves to navigate it. I told her that if she wanted to survive in physics, she needed to be twice as good, twice as careful, twice as prepared.
This advice was pragmatic, but it was also demoralising. It placed the burden on her to compensate for institutional sexism rather than on the institution to change. I see that now more clearly than I did then. At the time, I believed I was equipping her with the tools she needed to succeed. But I also wonder whether I was simply perpetuating the system by teaching women to accommodate it rather than resist it.
Now, you ask whether I worried this might reinforce the idea that women needed special treatment. Yes, I worried about this constantly. But I made a judgement: it was better to acknowledge the reality of discrimination privately and prepare women to face it, than to pretend equality existed when it manifestly did not. If I had treated women exactly as I treated men – with the same expectations, the same casual corrections, the same assumptions of competence – I would have been sending them into a profession that would evaluate them far more harshly than I did.
Contemporary research on mentorship, you say, suggests that the most effective support comes from acknowledging rather than obscuring differences. I find this validating, but also somewhat bitter. It means that my generation of women scientists was correct in our instincts, but we were working in isolation, without the scholarly framework or institutional support that might have made our efforts less exhausting.
I will also say this: the burden of preparing women for structural barriers should not fall on individual women mentors. It should fall on institutions. But in the 1950s and 1960s, institutions were not interested in this work. So it fell to us – Lise Meitner in her correspondence with younger physicists, Ellen Gleditsch in her mentorship of Norwegian women scientists, myself in my laboratory. We did what we could with the tools we had.
Did I do it well? I do not know. Some of the women I trained went on to productive careers. Others left physics, frustrated by the barriers they encountered. I cannot know whether different mentorship would have changed those outcomes. But I can say that I tried to be honest with them about what they would face, and I tried to give them the skills and the resilience to face it. Whether that was the right approach, history will judge.
Marcus Holloway (38, Nuclear Physicist and Science Communicator, Boston, North America)
Your work on X-ray crystallography under Bragg and your later radiochemistry created an unusual hybrid expertise – you could read crystal structures and measure radioactive decay with precision. In modern physics, we talk about interdisciplinary work as though it’s novel, but you were essentially doing that in the 1930s. How did you move between those two very different experimental cultures – crystallography’s focus on structural geometry versus radiochemistry’s focus on temporal processes and decay rates? Did the cognitive shift between them ever feel jarring, or did you find they reinforced each other intellectually?
Ah, now this is a question that gets at something I rarely discussed but found endlessly fascinating. You are quite right that crystallography and radiochemistry represent very different experimental cultures – different temporalities, different spatial scales, different intellectual frameworks. Moving between them was not merely a matter of learning new techniques; it required shifting one’s entire way of thinking about matter.
Let me explain what I mean. Crystallography, as I practised it under William Henry Bragg, is fundamentally concerned with structure – with the spatial arrangement of atoms in three-dimensional lattices. When you perform X-ray diffraction, you are capturing a snapshot of atomic architecture. The crystal is static, or at least we treat it as static. Time does not enter the calculation except as an experimental parameter – how long you expose the photographic plate to accumulate sufficient diffraction spots. The intellectual work is geometrical. You are solving a puzzle: given these diffraction angles and intensities, what arrangement of atoms could produce them? It is beautiful, precise, architectural thinking.
Radiochemistry, by contrast, is fundamentally concerned with process – with transformation over time. Radioactive decay is a temporal phenomenon. An atom of uranium-238 exists in a metastable state, and at some unpredictable moment, it will emit an alpha particle and transform into thorium-234. You cannot prevent this. You cannot predict when it will happen for any individual atom. All you can do is measure the statistical rate across large populations. The intellectual work is probabilistic and dynamic. You are tracking changes, measuring half-lives, following decay chains through sequences of transmutations.
So the cognitive shift between them – yes, it was jarring at first. When I returned to Vienna from Bragg’s laboratory in 1930 and resumed work on radioactive decay, I found myself thinking in crystallographic terms. I would try to visualise the atomic structure of radioactive materials, to imagine the spatial arrangements that might influence decay rates. This was not entirely wrong – crystal structure does affect certain decay processes, particularly internal conversion and electron capture – but it was not the primary framework for understanding alpha and beta decay.
It took me several months to retrain my thinking, to stop trying to impose spatial reasoning on temporal processes. I had to learn to think in terms of probability distributions, decay constants, equilibrium states. These are not architectural concepts; they are statistical and thermodynamic concepts.
But here is what I discovered: once I had made that cognitive shift, the two modes of thinking began to reinforce each other in unexpected ways. Let me give you a concrete example.
When we were working on the uranium content of seawater in the early 1930s, we needed to concentrate uranium from enormous volumes of water. The chemical procedure involved co-precipitation with ferric hydroxide, then dissolution and purification through solvent extraction. But the efficiency of co-precipitation depends on the crystal structure of the precipitate. If ferric hydroxide precipitates too quickly, it forms an amorphous gel that traps uranium poorly. If it precipitates slowly under controlled conditions, it forms a more crystalline structure with specific binding sites where uranium can substitute for iron.
My crystallographic training allowed me to reason about this in a way that purely radiochemical training might not have. I understood that precipitation is not merely a chemical reaction; it is a crystallisation process. The spatial arrangement of ions in the growing crystal determines which impurities – including uranium – will be incorporated. By controlling the precipitation conditions – pH, temperature, rate of reagent addition – we could influence the crystal structure and thereby improve uranium recovery.
This might seem like a minor technical detail, but it was the difference between a procedure that recovered 60 per cent of uranium and one that recovered 95 per cent. That difference was crucial for measuring the extraordinarily low concentrations in seawater.
Similarly, when Traude Bernert and I were working on natural astatine, we faced the challenge of separating element 85 from bismuth and polonium, which have similar chemical properties. Astatine is a halogen, so it should behave chemically like iodine, but at the trace concentrations we were dealing with – vanishingly small amounts – normal chemical separation techniques were unreliable.
What saved us was reasoning about adsorption onto crystal surfaces. We used the fact that different elements adsorb preferentially onto different crystal faces depending on their ionic radii and electronic configurations. By controlling the crystal structure of our adsorbent materials – we used metallic silver and certain oxide crystals – we could achieve separation that would have been impossible through purely solution-phase chemistry.
Again, this required thinking crystallographically about a radiochemical problem. The temporal process – radioactive decay – was occurring in materials whose spatial structure influenced chemical behaviour.
So did the cognitive shift feel jarring? Yes, initially. But it became generative. I learned to move fluidly between spatial thinking and temporal thinking, between structure and process, between geometry and statistics. This is what interdisciplinary work truly means – not merely using techniques from different fields, but integrating different modes of reasoning.
There is another dimension worth mentioning: the cultural differences between the two fields. Crystallography in the 1930s was a relatively new discipline, dominated by British physicists – the Braggs, Kathleen Lonsdale, J.D. Bernal. It had a certain intellectual elegance, a sense of solving pure puzzles. Papers were written with geometric clarity. Structures were described with precision and beauty.
Radiochemistry, particularly in the Continental tradition, was more empirical, more rooted in chemical intuition. Papers documented experimental procedures in exhaustive detail. There was less emphasis on theoretical elegance and more emphasis on reproducibility and quantitative accuracy. The culture valued patience, meticulousness, and experimental craft.
Moving between these cultures required not just intellectual flexibility but also social 0adaptation. I had to learn to write differently, to present results differently, to engage with different standards of evidence and argument. This was perhaps the most challenging aspect – not the scientific content, but the rhetorical and social dimensions of belonging to two different research communities.
Did they reinforce each other intellectually? Absolutely. The crystallographic habit of visualising structures made me a better radiochemist because I could think spatially about where radioactive atoms were located in materials, how they might migrate, how they might interact with their crystalline environment. The radiochemical habit of thinking about temporal processes made me appreciate that crystal structures are not truly static – atoms vibrate, defects migrate, surfaces reconstruct. Both perspectives were necessary for complete understanding.
In some ways, I believe my hybrid expertise was an advantage that the more specialised physicists lacked. They knew their field deeply but narrowly. I knew two fields moderately well, and the intersection between them became my particular niche. That is where the natural astatine discovery emerged – from understanding both the temporal dynamics of decay chains and the spatial chemistry of element separation.
So to answer your question directly: yes, the shift was jarring. But it was also profoundly enriching. And I would encourage any young scientist to seek out such cognitive tensions, because that is where genuine insight often emerges – not from mastery of a single mode of thinking, but from the friction between two different ways of understanding the world.
Samira Mtembu (29, Medical Physicist specialising in Cancer Therapy, Cape Town, Africa)
Astatine-211 therapy is now being tested for cancers that historically have had poor prognosis, and the work traces directly back to your natural astatine discovery. But I want to ask something practical: when you proved astatine occurs naturally, did you have any intuition that it would eventually be useful for medicine? Or was it purely fundamental curiosity about the periodic table? I ask because it shapes how I think about my own work – whether we should be consciously hunting for medical applications or whether the most important discoveries come from following the science without that pragmatic lens.
This is a profound question, and one that goes to the heart of how we understand the purpose of scientific work. When Traude and I proved that astatine occurs naturally, did we have any intuition it would be medically useful? The honest answer is no – not in any specific sense. We were not thinking about cancer therapy. We were thinking about the periodic table, about decay chains, about whether nature produces all possible elements or only some subset of them.
But let me complicate that answer, because I think the question you are really asking is more subtle. You are asking whether scientists should consciously hunt for applications, or whether we should follow pure curiosity and trust that applications will emerge. This is an old debate – some call it the distinction between pure and applied science – and I have thought about it considerably over the years.
In 1942, when we published our findings, element 85 was a curiosity. It had been synthesised artificially at Berkeley two years earlier, but it had no known uses. It was simply the next element in the halogen series – below iodine, below bromine, below chlorine. We wanted to know whether it existed in nature because that question told us something fundamental about nuclear processes. If astatine occurred naturally, it meant that the uranium and thorium decay chains produced it as an intermediate product. That was interesting from the standpoint of understanding how elements are distributed in the Earth’s crust, how radioactive equilibrium works, and how the periodic table maps onto actual natural processes.
Did we imagine medical applications? Not explicitly. But – and this is important – we were not working in complete ignorance of the broader context. By the 1940s, it was already known that radioactive materials could affect biological tissue. Marie Curie had died in 1934 from aplastic anaemia caused by radiation exposure. We knew that alpha particles were particularly damaging to cells because of their high energy and short range. We knew that certain radioactive isotopes – radium-226, radon-222 – were being used experimentally in cancer treatment, inserted directly into tumours to destroy malignant tissue.
So while we did not specifically think “astatine will be useful for cancer therapy,” we were aware that radioactive elements with certain properties – short half-lives, alpha emission, chemical behaviour that allows targeting – could potentially be useful in medicine. This awareness was in the background, part of the general knowledge of any physicist working with radioactive materials.
Now, here is where I must be careful in my answer, because I do not want to claim prescience I did not possess. I did not foresee targeted alpha therapy. I did not imagine antibody conjugates or specific molecular targeting mechanisms. Those developments required advances in biochemistry, immunology, and radiopharmaceutical chemistry that did not exist in the 1940s. What I knew was that understanding the fundamental properties of elements – their decay modes, their half-lives, their chemical behaviour – was necessary groundwork for any future application.
This brings me to your larger question: should you be consciously hunting for medical applications, or should you follow the science without that pragmatic lens?
My answer is both, but in a particular sequence. First, you must understand the fundamental science. You must know what is true about the natural world, independent of whether it is useful. This requires curiosity-driven research – research that asks “what is?” rather than “what can we do with this?” If Traude and I had been focused solely on medical applications, we would not have investigated natural astatine, because there was no obvious medical reason to care whether it occurred naturally or only artificially. We investigated it because it was an unanswered scientific question.
But once you understand the fundamental science, you have a responsibility to consider applications. Not to force them, not to distort your research to fit some anticipated use, but to remain aware of potential connections. In my later years, as astatine-211 began to be investigated for medical purposes in the 1970s and 1980s, I followed that work with great interest. I corresponded with researchers who were exploring its use in therapy. I felt a certain satisfaction – not because I had anticipated this application, but because the fundamental work we had done decades earlier was now proving useful in ways we had not imagined.
Here is what I learned from this: the most important discoveries are often those that answer fundamental questions without immediate application. They create knowledge that sits quietly in the scientific literature, waiting for someone to recognise its usefulness when the time is right. If we had not proven that astatine occurs naturally, if we had not measured its decay properties, if we had not documented its chemical behaviour, the later medical researchers would have had to do that work themselves before they could even begin investigating therapeutic applications. We gave them a foundation.
So my advice to you is this: do not abandon curiosity-driven research in favour of application-driven research. But also do not treat them as entirely separate. The best science maintains a dual awareness – pursuing fundamental understanding whilst remaining alert to potential applications. You do not need to know exactly how your work will be useful, but you should cultivate a habit of asking “what might this make possible?” without allowing that question to dictate your research programme.
Let me give you a practical example from your own field. You are working on astatine-211 targeted alpha therapy for aggressive cancers. The fundamental question you must answer is: how do we deliver astatine-211 to tumour cells with sufficient specificity and stability? This requires understanding the radiochemistry of astatine, the biochemistry of targeting molecules, the cellular uptake mechanisms, the dosimetry. Some of this work will have immediate clinical relevance. But some of it – understanding exactly how astatine bonds to organic molecules, measuring decay properties in biological environments, characterising daughter products – is fundamental science that may not have immediate therapeutic application but will be essential for future developments.
If you focus solely on the immediate clinical goal – curing this specific cancer in this specific patient population – you may miss opportunities to develop more general knowledge that could be applied to other cancers, other isotopes, other targeting strategies. But if you focus solely on fundamental understanding without any awareness of clinical needs, you may pursue questions that are scientifically interesting but practically irrelevant.
The balance is difficult. I do not pretend I always achieved it. But I believe the correct approach is to let curiosity guide the questions you ask, whilst allowing practical awareness to inform which questions you prioritise and how you communicate your findings.
One final thought: the path from discovery to application is often long and unpredictable. Traude and I published our astatine work in 1942. Serious medical applications did not emerge until the 1980s and 1990s – four decades later. If we had judged the value of our work solely by immediate practical utility, we would have considered it a failure. But we judged it by whether it answered a fundamental question about the natural world, and by that measure, it succeeded. The medical applications emerged in their own time, when other fields – biochemistry, molecular biology, medical physics – had advanced sufficiently to make them possible.
So follow the science. Understand it deeply. Document it carefully. And trust that if the work is rigorous and the questions are important, the applications will reveal themselves when the time is right. That is not a guarantee, but it is the best approach I know.
Reflection
Berta Karlik died on 4th February 1990, at the age of eighty-five, having worked at the Institut für Radiumforschung until the very end. She lived long enough to witness the earliest investigations into astatine-211 for medical applications, though the full flowering of targeted alpha therapy came after her death. One wonders what she would have made of contemporary clinical trials using her element to attack glioblastomas and metastatic cancers – whether she would have felt vindicated, or whether, true to her character, she would have simply noted that good fundamental science eventually finds its purpose.
The themes that emerged throughout this interview – perseverance, intellectual rigour, the quiet costs of being “first,” and the erasure of women’s contributions from scientific narratives – speak to patterns that extend far beyond one physicist’s career. Karlik’s description of holding women to higher standards in her laboratory, her candid admission that she taught them to accommodate rather than resist institutional barriers, and her reflections on the loneliness of wartime isolation reveal a woman navigating impossible choices with imperfect tools. She was neither victim nor hero in any simple sense, but rather a scientist doing rigorous work under circumstances that demanded both excellence and strategic compromise.
Where her perspective may differ from recorded accounts is in her frank acknowledgement of ambivalence. Historical treatments often present her appointment as the first female full professor at the University of Vienna in 1956 as a triumphant milestone. In conversation, she described it as simultaneously an achievement, a burden, and a token gesture – recognition that came with the weight of representing all women whilst being scrutinised for any hint of inadequacy. She also expressed uncertainty about her decision to remain in Vienna during the Nazi period, a choice rarely interrogated in biographical accounts that focus primarily on her scientific accomplishments.
The historical record contains gaps and contested interpretations. The relative obscurity of Karlik and Traude Bernert’s natural astatine discovery – overshadowed by the Berkeley synthesis – reflects broader patterns in how scientific credit is allocated. Geographic marginalisation, wartime isolation, and the dynamics of collaborative discovery by women all contributed to the invisibility of their work in mainstream narratives. Recent efforts, including the “Unsung Women” project highlighted by Nature in 2019, have begun to correct this erasure, but Karlik’s name remains far less recognisable than those of male contemporaries with comparable achievements.
Her work’s afterlife demonstrates the unpredictable pathways of scientific influence. Researchers developing astatine-211 radiopharmaceuticals in the 1980s and beyond relied on the decay properties and chemical behaviour she documented in the 1940s. Contemporary environmental radioactivity studies – monitoring uranium in seawater, assessing contamination from nuclear accidents, measuring background radiation – use refined versions of the scintillation counting techniques she helped pioneer. Her crystallographic training under William Henry Bragg contributed to understanding how crystal structure influences radioactive element behaviour, a principle now applied in radiation detector design and nuclear waste storage research.
Perhaps most significantly, Karlik’s insistence on the interdisciplinary integration of crystallography, radiochemistry, and environmental science prefigured the contemporary recognition that complex problems require hybrid expertise. Her ability to think spatially about temporal processes, to move fluidly between structure and decay, between geometry and statistics, models the cognitive flexibility increasingly valued in modern research.
For young women pursuing science today, Karlik’s story offers both inspiration and cautionary insight. She achieved institutional recognition in an era of profound discrimination, maintained international networks when borders closed, and produced discovery during wartime isolation. But she also paid costs: the exhaustion of being perpetually scrutinised, the burden of mentoring women to accommodate rather than confront barriers, the loneliness of working at the margins of dominant scientific centres.
Her legacy asks uncomfortable questions: How much has genuinely changed? Women remain underrepresented in physics, particularly at senior levels. Geographic inequality persists in how scientific contributions are recognised and valued. Collaborative work by women continues to receive less credit than solo male achievement. Yet Karlik’s career also demonstrates that rigorous science, strategic networking, and intellectual courage can create space for discovery even under profound constraint.
What lingers most powerfully from this conversation is her measured honesty – her refusal to romanticise either her accomplishments or her struggles. She was not exceptional despite being a woman; she was a competent physicist who navigated structural barriers with intelligence and persistence. That distinction matters. It shifts the problem from individual exceptionalism to institutional failure, and in doing so, makes clear where the work of change must occur. Berta Karlik proved that nature makes its own astatine. We must now prove that institutions can make space for all who pursue understanding, regardless of who they are or where they work.
Who have we missed?
This series is all about recovering the voices history left behind – and I’d love your help finding the next one. If there’s a woman in STEM you think deserves to be interviewed in this way – whether a forgotten inventor, unsung technician, or overlooked researcher – please share her story.
Email me at voxmeditantis@gmail.com or leave a comment below with your suggestion – even just a name is a great start. Let’s keep uncovering the women who shaped science and innovation, one conversation at a time.
Editorial Note
This interview is a fictional dramatisation based on historical sources, biographical accounts, and documented information about Berta Karlik‘s life and scientific work. Whilst the scientific details, institutional contexts, and major biographical facts are grounded in historical record, the dialogue itself – Berta Karlik’s voice, her specific phrasings, her personal reflections, and the conversational exchanges – has been reconstructed imaginatively.
We do not possess recordings or transcripts of Karlik speaking at length about her career, her motivations, or her personal experiences. Statements attributed to her in this interview have been constructed to reflect what historical evidence suggests she valued, believed, and accomplished, informed by her published papers, known correspondence with colleagues like Lise Meitner and Ellen Gleditsch, institutional records from the University of Vienna and the Institut für Radiumforschung, and biographical scholarship on her life and achievements.
The technical descriptions of her experimental methods – scintillation counting, uranium concentration procedures, X-ray crystallography, astatine detection – are based on actual techniques documented in scientific literature from her era and in accounts of her research. The descriptions of her navigation of institutional barriers, her mentorship approaches, and her reflections on wartime isolation represent plausible interpretations grounded in historical context, though they necessarily involve imaginative reconstruction of her internal experience.
This dramatisation serves to humanise a historical figure whose contributions have been obscured by time and structural erasure, whilst honouring the documented facts of her life. It is offered as a means of engaging readers with Karlik’s scientific work and her historical significance, not as a literal transcript or biographical claim.
Readers seeking detailed historical information are encouraged to consult scholarly sources, including academic articles on Karlik’s research, the “Unsung Women” project documentation, and archival materials held at the University of Vienna. This interview aims to complement rather than replace rigorous historical study, offering one imaginative entry point into understanding a remarkable scientist whose work continues to shape contemporary physics and medicine.
Bob Lynn | © 2025 Vox Meditantis. All rights reserved.
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