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Joseph Rotblat: What led the nuclear peace activist to quit the Manhattan Project?

Joseph Rotblat was once associated with the Manhattan Project, which led to the invention of nuclear weapons. But what made him change his heart to quit the project and fight against nuclear weapons for the rest of his career?

Karthik Vinod

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Credit: Jijin M.K. / EdPublica

Are all scientific advancements beneficial to humankind? No. But then why do we invent them?

Nuclear weapons were seen by many of the Manhattan Project scientists, famously Robert Oppenheimer, thought it was necessary evil

But Joseph Rotblat, a Polish nuclear physicist was one of the first converts who left the Manhattan Project, to advocate for a total reversal and elimination of nuclear weapons.

A political chain reaction ensued following the war, with world powers scrambling nuclear weapons claiming deterrence. These weapons meanwhile grew ever more powerful in capacity, to cause more misery and damage. In fact, there’s enough nuclear weapons shared between the US and Russia now, to annihilate human civilization itself.

Then, Rotblat entered the fore setting up the Pugwash Conference on Science and World Affairs in 1957, with British philosopher and mathematician Bernard Russell, to advocate for phasing out nuclear weapons. Pugwash Conferences were influential and successful in bringing scientists and scholars across ideological spectrums to debate solutions while advocating for a nuclear weapon-free world. It helped influence policy decisions – pushing for test ban treaties in international politics. 

The Cold War then ended, and there was some relief – the world hadn’t gone into For Rotblat and Pugwash’s efforts, they were jointly awarded the 1995 Nobel Peace Prize, “for their efforts to diminish the part played by nuclear arms in international politics and, in the longer run, to eliminate such arms.” 

However, it’s perhaps interesting to know what really drove the now revered nuclear peace activist to even join the nuclear weapons program in the first place. 

Nuclear fission and World War II

For one, he too was driven like many in his generation, prior to World War II that Adolf Hitler’s Germany could develop and use a nuclear bomb. Germany was then the superpower in physics, although it stagnated following mass resignations and boycotts against Jewish physicists – many of whom heralded the 20th century revolution in physics – including the likes of Albert Einstein and Max Planck.

Rotblat had moved to Liverpool, UK in 1939 from his native Poland to learn how to build a cyclotron with James Chadwick – the physics Nobel laureate who discovered the subatomic neutron particle. As much as he successfully split the uranium nucleus, he was split from his wife in Poland forever – at the onset of World War II.

Tola was ailing from appendicitis, because of which she couldn’t make it to Liverpool before war broke out. Despite Rotblat’s efforts to seek asylum in the UK, she never escaped. The last Rotblat heard from her was through a letter in December 1940. Rotblat was clearly distraught – although at the same time, he spent his time and energy with the fast neutron research group with Chadwick back in Liverpool.  Rotblat would never know until the war would end, that Tola and her mother were killed at the Belzec concentration camp in occupied Poland by 1941. 

Unbeknownst to him, the British military intelligence did know about Tola’s death back in 1941, though Rotblat wasn’t informed then. Rotblat’s psyche was quite different from other physicists. 

Joseph Rotblat’s badge photograph during the Manhattan Project. Credit: Los Alamos Laboratory / Wikimedia

When the Quebec Agreement was signed by the UK to help the US with the Manhattan Project, Rotblat had his conscience stricken. Physicists apparently had their set of reasons to join this war-time effort to develop a bomb. Rotblat, like most others, willingly joined the Project believing inventing the bomb can offer deterrence against a German bomb. Many others, in Rotblat’s own admission, simply joined to not have their careers jeopardized by the government.

A mentor in Ludwik Wertenstein 

Rotblat was a ‘pure scientist’ in that he seeked to avoid the moral scrupulousness that he knew would plague him if it turned out that the nuclear weapon would be used. Back in Poland when he was an undergrad, he found a mentor in the Polish experimental physicist, Ludwik Wertenstein. Rotblat mentioned how Wertenstein helped find something about himself – concurring with the belief that science wasn’t neutral, or wasn’t some discipline divorced from our social reality. And thus scientists themselves were partly answerable for reasons of its end-usage. Rotblat saw in Wertenstein who he too was – a strong believer in ethics. 

Ludwik Wertenstein. Credit: Wikimedia

Rotblat would have remembered what Wertenstein would advise him when he was stuck between a rock and a hard place. Use your conscience, he would say. To Rotblat, Wertenstein was a ‘counselor and friend’ in addition to being a teacher. Rotblat had briefed Wertenstein, before the latter joined the Polish war effort, about Germany potentially developing a nuclear bomb. Wertenstein was clear that he wouldn’t work on a program to deter Germany, at the cost of abandoning his core moral principle of bringing benefit to all mankind. 

Fortunately for Rotblat, he had an option to quit the Manhattan Project almost as soon as he had arrived. Military intelligence in 1944 confirmed the Germans had abandoned their efforts to develop a nuclear bomb. Rotblat, seeing no reason to develop one, was allowed to leave. 

Researching ‘nuclear medicine’ to save lives

After learning of his wife Tola’s death, he refused to remarry. He was now armed with a newfound conviction to end his association with his career in nuclear research on a better note. 

Wertenstein’s persona captured him truly in that he made advances to unleash nuclear energy in a form to save people’s lives rather than take away them.

In 1949, Rotblat joined Londons’ St. Bartholomew’s Hospital, as Professor of Medical Physics. There, he made phenomenal advances in nuclear medicine, for instance studying the biological effects of radioactivity – and research that would help his case to bring to light the effects nuclear weapons would have on the human body. 

He even at one stage suggested young scientists graduate from universities taking a Hippocratic Oath like medical doctors do. 

At his Nobel Lecture titled ‘Remember Your Humanity’, Rotblat stressed on the need for scientists to take up ownership for their work’s impact on society.  

“You are doing fundamental work, pushing forward the frontiers of knowledge, but often you do it without giving much thought to the impact of your work on society. Precepts such as ‘science is neutral’ or ‘science has nothing to do with politics,’ still prevail. They are remnants of the ivory tower mentality, although the ivory tower was finally demolished by the Hiroshima bomb.” 

Rotblat’s journey has some insights for the world we live in today. He said in the same Nobel Lecture, that our post-Cold War world doesn’t require Cold War thinking. Although the major nuclear powers are all signatories of the Non-Proliferation Treaty (NPT), nuclear arsenals are yet to be phased out.

With nuclear powers unwilling to relent and work through a solution, only scientists can play a vital role. How? By simply doing what Rotblat did. Leave holding your head held high.

Karthik is a science writer, and co-founder of Ed Publica. He writes and edits the science page. He's also a freelance journalist, with words in The Hindu, a prominent national newspaper in India.

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Pierre Curie: The precision of a scientific pioneer

Pierre Curie is perhaps best known for his work on magnetism

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Pierre Curie image source: Wikimedia Commons

Pierre Curie (1859–1906) was a man whose legacy has shaped the course of modern science, yet his name is often overshadowed by that of his famous wife, Marie Curie. Despite this, Pierre’s contributions to physics, particularly in the field of magnetism and the discovery of radioactivity, were revolutionary and continue to influence scientific research today.

Early Life and Education

Born in Paris on May 15, 1859, Pierre Curie grew up in an intellectually stimulating environment. His father, Eugene, was a physician, and his mother, Sophie, was a teacher, which cultivated in Pierre a deep passion for learning. From an early age, Pierre showed an exceptional aptitude for mathematics and physics, subjects that would later define his career.

By the time Pierre was 16, he had already completed his studies in mathematics and physics, earning a degree from the prestigious Sorbonne University in Paris. This early foundation in scientific inquiry laid the groundwork for his future innovations.

In 1895 together with his brother Jacques Curie, Pierre Curie developed the Curie point—the temperature at which certain magnetic materials lose their magnetism

Innovative Work in Magnetism and Crystallography

Pierre Curie is perhaps best known for his work on magnetism. In 1895, together with his brother Jacques Curie, he developed the Curie point—the temperature at which certain magnetic materials lose their magnetism. This work, foundational in the study of thermodynamics and magnetism, continues to be a key concept in modern physics.

Additionally, Pierre Curie’s research in crystallography and his study of the magnetic properties of materials played a pivotal role in the development of solid-state physics. His work laid the foundation for understanding the relationship between a material’s structure and its magnetic properties, which remains essential in materials science today.

The Discovery of Radioactivity

However, Pierre Curie’s most significant contribution came from his work on radioactivity, which would forever alter the understanding of matter itself. In the late 19th century, the mysterious rays emitted by certain substances, like uranium, intrigued scientists. Working alongside his wife, Marie Curie, Pierre embarked on a series of experiments to better understand this phenomenon.

Their work, starting in 1898, led to the discovery of two new elements: polonium and radium. Marie Curie coined the term “radioactivity” to describe the spontaneous emission of radiation from these elements, but it was Pierre’s precise experimental methods and scientific rigor that helped bring clarity to the phenomenon. Their discovery of radium, in particular, was a breakthrough that would lead to numerous advancements in medical treatments, including cancer therapy.

Nobel Recognition and Collaboration with Marie Curie

In 1903, Pierre Curie, together with Marie Curie and Henri Becquerel, was awarded the Nobel Prize in Physics for their joint work on radioactivity. The recognition marked the first time a Nobel Prize had been awarded to a couple. However, what makes this achievement particularly notable is that Pierre Curie insisted that Marie be included in the award, a gesture that demonstrated not only his scientific partnership with his wife but also his support for women in science, a rare stance in the male-dominated field of the time.

Tragically, Pierre Curie’s life was cut short in 1906 when he was killed in a street accident at the age of 46

Pierre Curie’s dedication to scientific rigor and his ability to work collaboratively with Marie, his wife and fellow scientist, was vital to their success. Their work would not only earn them the Nobel Prize but also set the stage for later advancements in nuclear physics and medicine.

Tragic Loss and Enduring Legacy

Tragically, Pierre Curie’s life was cut short in 1906 when he was killed in a street accident at the age of 46. His death was a blow to both the scientific community and his family. However, his legacy continued through his wife, Marie, who carried on their groundbreaking work and became the first woman to win a second Nobel Prize.

Today, Pierre Curie is remembered as a visionary physicist whose discoveries were instrumental in shaping the fields of physics, chemistry, and medicine. His contributions to magnetism, crystallography, and radioactivity remain foundational to scientific inquiry. His work continues to inspire scientists across disciplines and serves as a reminder of the power of precision, collaboration, and dedication in the pursuit of knowledge.

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The ‘Godfather of AI’ has a warning for us

The speed with which large language models such as ChatGPT has come to the fore has re-invigorated serious discussion about AI ethics and safety among scientists and humanities scholars alike.

Karthik Vinod

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Credit: Jijin M.K. / Ed Publica

The quest to develop artificial intelligence (AI) in the 20th century had entrants coming in from various fields, mostly mathematicians and physicists.

Geoff Hinton, famously known as the ‘godfather of AI’ today, at one point dabbled in cognitive psychology as a young undergraduate student at Cambridge. Allured by the nascent field of AI in the 1970s, Hinton did a PhD from Edinburgh where he helped revive the idea of artificial neural networks (ANNs). These ANNs mimic neuronal connections in animal brains, and has been the staple of mainstream research into AI. Hinton, a British-born Canadian, since then moved to the University of Toronto, where he’s currently a professor in computer science.

In 2018, Hinton’s contributions to computer science and AI caught up to him. He was awarded a share of the coveted Turing Award, which is popularly known as the ‘Nobel Prize in Computing’. His 1986 work on ‘back propagation’ helped provide the blueprint to how machines learn, earning him the popular recognition of being one of the ‘fathers of deep learning’ as well.

The last two years saw artificial intelligence become commonplace in public discourse on technology. Leading the charge was OpenAI’s ChatGPT, as large language models (LLMs) found use in a whole host of settings across the globe.  OpenAI, Google, Microsoft and their likes are engaged in upping the ante.

But this sudden spurt has alarmed many and is re-invigorating a serious discussion about AI ethics and safety. Last year, Elon Musk was amongst signatories of a letter requesting to halt AI research for a while, fearing the ever-increasing odds that sentient AI may be in the horizon. But sociologists believe this risk is simply overplayed by billionaires to avoid the real-world problems posed by AI gets swept under the carpet. For example, job losses will occur for which there is no solution in sight about what should be done to compensate those who may lose their work.

However, in a very technical sense, computer scientists like Hinton have taken to the fore to make their views explicitly clear. In fact, Hinton ended his decade long association with Google last year to speak freely about what he thought was a competition between technology companies to climb upon each other’s advances. He, like many computer scientists, believe humanity is at a ‘turning point’ with AI, especially with large language models (LLMs) like ChatGPT at the fore.

“It’s [LLMs] very exciting,” said Hinton in a Science article. “It’s very nice to see all this work coming to fruition. But it’s also scary.” 

One research study suggests these LLMs are anything but ‘stochastic parrots’ that outputs what it’s been instructed to do. This doesn’t mean AI is anywhere close to being sentient today. However, Hinton and other computer scientists fear humanity may unwittingly run into the real risk of creating one. In fact, Hinton was one of several signatories of an open letter requesting policy makers to consider the existential risk of AI.

Creating a sentient AI, or artificial general intelligence (AGI, as it’s technically called) would vary in definition based on scientists researching them. They don’t exist for one today, and nobody safe to say knows what it would look like. But in popular lore, these can simply mean Skynet from the Terminator movies, becoming ‘self-aware’. Hinton was of the opinion that AI already surpassed biological intelligence in some ways. However, it must be bore in mind that AI isn’t anymore a stochastic parrot than it is sentient. Hinton doesn’t say more powerful AI would make humans all redundant. But AI could do many routine tasks humans already do, and thus replace them in those in time. Navigating them is a task that requires views that are transdisciplinary.

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The astrophysicist who featured in TIME’s most influential personality list

Priyamvada Natarajan’s contributions in astronomy helped shed light into two major research interests in contemporary astrophysics – the origins of supermassive black holes, and mapping dark matter in the universe.

Karthik Vinod

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Credit: Jijin M.K. / EdPublica

For Priyamvada Natarajan, her earliest exposure to scientific research arose from her childhood passion making star maps. Her love for maps never abated, and shaped her career as a theoretical astrophysicist. In the media, she’s the famous ‘cosmic cartographer’, who featured in the TIME magazine’s list of 100 most influential personalities this year.

“I realise what an honour and privilege this is,” said Natarajan to The Hindu. “It sends a message that people working in science can be seen as influential, and that is very gratifying.”

The Indian-American’s claim to fame arises from her pathbreaking research into dark matter and supermassive black holes.

She devised a mathematical technique to chart out dark matter clumps across the universe. Despite dark matter being invisible and elusive to astronomers, they’re thought to dominate some 75% of the universe’s matter. Dark matter clumps act as ‘scaffolding’, in the words of Natarajan, over which galaxies form. When light from background galaxies gets caught under the gravitational influence of dark matter clumps, they bend like they would when passed through a lens. Natarajan exploited this effect, called gravitational lensing, to map dark matter clumps across the universe.

Simulation of dark matter clumps and gas forming galaxies. Credit: Illustris Collaboration

Natarajan reflected her passion for mapping in a TEDx talk at Yale University, where she’s professor of physics and astronomy. Though she’s an ‘armchair’ cartographer, in her own description, she has resolved another major headwind in astronomy – nailing down the origins of supermassive black holes.

Black holes generally form from dying stars, after they collapse under their weight due to gravity. These black holes would swallow gas from their environment to grow in weight. However, there also exists supermassive black holes in the universe, millions of times heavier than any star or stellar-sized black hole, whose formation can’t be explained by the dying star collapse theory. One example is Sagittarius A* at the center of the Milky Way, which is a whopping four million times massive than our sun.

First direct image of Sagittarius A* at the Milky Way center. Credit: EHT

The origins of these behemoths remained in the dark until Natarajan and her collaborators shed some light to it. In their theory, massive clumps of gas in the early universe would collapse under its own weight to directly form a ‘seed’ supermassive black hole. This would grow similar to its stellar-massed counterparts by swallowing gas from its environment. In 2023, astronomers found compelling evidence to validate her theory. They reported a supermassive black hole powering the ancient quasar, UHZ1, at an epoch when no black hole could possibly have grown to attain such a massive size.

These observations came nearly two decades following Natarajan’s first paper on this in 2005. In a 2018 interview to Quanta, she expressed how content she would be with her contributions to astrophysics without having her theory requiring experimental verification done within her lifetime. For, she would be simply content at having succeeded at having her ideas resonate among astronomers for them to go search for her black holes. “I’m trying to tell myself that even that would be a supercool outcome,” she said in that interview. “But finding [the supermassive black hole ‘seed’] would be just so awesome.”

Beyond science, Natarajan’s a well-sought public speaker as well, with pursuits in the humanities as well. In fact, at Yale University, she’s the director of the Franke Program in Science and the Humanities, which fosters links between the two disciplines. Her humanities connect comes at MIT, where she did degrees in physics and mathematics before taking a three-year hiatus from science to explore her interest in the philosophy of science. However, she returned to astronomy soon thereafter, enrolling as a PhD student at Cambridge, where she worked under noted astronomer Martin Rees on black holes in the early universe which seeded her success in later years.

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