1935

Nobel Prize in Physics

The Particle With No Alarm to Trip

James Chadwick

In 1932, James Chadwick at the Cavendish Laboratory in Cambridge had noticed that bombarding beryllium with alpha particles produced a penetrating radiation that didn't behave like gamma rays — it was, after some careful arithmetic and sleepless days, a particle of roughly proton mass and no charge at all. The neutron, as he called it, slipped past the Coulomb barrier that repels charged particles away from nuclei, meaning it could wander straight into an atomic nucleus and do things there that a proton never could. The committee took three years to catch up, which in retrospect seems leisurely given what the neutron was already being pressed into service for. Without it, there is no controlled fission, no tracer isotope in medicine, no way to interrogate the interior of a nucleus at all — the entire subsequent story of nuclear physics runs through that unremarkable, electrically silent particle, like a key that fits every lock precisely because it doesn't trigger the alarm.

Nobel Prize in Chemistry

Radioactivity, Made to Order

Frédéric Joliot · Irène Joliot-Curie

Irène Joliot-Curie had grown up watching her mother Marie work with radioactive materials in conditions that were, to put it decorously, unprotected, and she entered the same field with the same rigour and rather more understanding of what it cost. She and her husband Frédéric, working in Paris, bombarded aluminium and boron with alpha particles and found that the targets continued emitting radiation after the bombardment stopped — they had produced phosphorus-30 and nitrogen-13, radioactive isotopes that did not exist in nature. The Nobel Committee recognised this in 1935 as the synthesis of new radioactive elements, the demonstration that radioactivity was a property you could confer rather than merely observe. It was an irony of the quietest kind that Marie Curie had died the previous year of aplastic anaemia, almost certainly from decades of exactly the kind of exposure this work required, and thus could not see her daughter receive the prize she herself had won twice. The daughter's achievement opened artificial radioisotopes to medicine, agriculture, and traceable chemistry, which is a legacy even a twice-laureate might have considered sufficient.

Nobel Prize in Physiology or Medicine

A Sliver of Tissue Gives Orders

Hans Spemann

Hans Spemann spent the better part of three decades doing extraordinarily fiddly things to salamander eggs — transplanting tiny slivers of embryonic tissue from one developing newt to another and watching what happened next. What happened next was consistently astonishing: a piece of tissue taken from the dorsal lip of the blastopore, transplanted into the flank of a second embryo, would cause a second complete nervous system to form there, as though the host tissue had been handed new instructions it couldn't decline to follow. Spemann called the responsible tissue the organiser, which turned out to be an act of understatement on the geological scale — it is, effectively, the region that tells an embryo which end will be the head, which will be the tail, and what ought to go between them. The mechanism was not understood for decades after his prize, and the molecular details of how the organiser signals took another half-century to unravel. But Spemann had established that development is not just genetic fate unfolding passively; it is a conversation between cells, and some cells are doing most of the talking.

Nobel Peace Prize

An Empty Chair in Oslo

Carl von Ossietzky

Carl von Ossietzky was a German pacifist journalist who, in 1931, published in his magazine Die Weltbühne the findings of a military correspondent who had documented Germany's secret rearmament in direct violation of the Versailles Treaty — clandestine aviation training, concealed weapons programmes, the whole careful fiction that a defeated Germany was disarming as agreed. The Weimar Republic imprisoned him for it; when the Nazis came to power in 1933, they sent him first to a prison camp at Papenburg-Esterwegen, then to a concentration camp, where he was by 1935 visibly and seriously ill. The Nobel Committee awarded him the Peace Prize that year, and the Nazis, furious, forbade any German from accepting a Nobel under any circumstances — a prohibition that remained on the books and produced three famously empty chairs in Stockholm in 1938. Ossietzky himself could not travel to Oslo; his chair sat empty at the ceremony, in an image that required no commentary. He died in 1938, still in German custody. The point had been made, though the audience most in need of making it had already stopped listening.

Szilard develops nuclear chain reaction concept

The Arithmetic That Frightened Its Author

Leó Szilard

Leó Szilard was crossing Southampton Row in London in September 1933 when, waiting for a traffic light, he worked out the essential arithmetic of a nuclear chain reaction: if a neutron striking a nucleus could release two neutrons, those two could strike two more, releasing four, and the multiplication from there was not slow. He was so alarmed by what he had just thought that he patented the idea the following year, then assigned the patent to the British Admiralty specifically to keep it secret, on the theory that a concept this dangerous should not be lying around for anyone to use. By 1935 he was refining the physics at Oxford, worrying over which elements might sustain the chain, and beginning what would become a years-long effort to persuade the broader physics community — with more success than he initially wanted — to stop publishing results that might help a hostile government build what he could see was coming. He was not wrong; he was merely early. The refugee Hungarian physicist who frightened himself at a London crossing would eventually help write the letter to Roosevelt that started the Manhattan Project, an outcome he spent the rest of his life trying to atone for.

First medical use of radioactive isotopes

A Dose That Seeks Its Own Target

The thyroid gland is, in its quiet way, a very convenient organ: it concentrates iodine from the bloodstream with a single-mindedness that no other tissue in the body matches, because iodine is what it needs to manufacture its hormones. This physiological habit, ordinarily unremarkable, became medically interesting in the mid-1930s when radioactive iodine — iodine-131, produced artificially following the Joliot-Curies' work on synthetic radioisotopes — was first used therapeutically for thyroid disease. The gland would collect the tracer just as faithfully as it collected the stable kind, and the radiation it emitted could be used to image the tissue or, in higher doses, to ablate overactive or malignant cells from within. It was, by the standards of contemporary medicine, a weapon of remarkable precision: a dose that sought its own target, delivered itself from the inside, and spared surrounding tissue with a selectivity that surgery could not match. The principle — that a biological specificity could be turned into a therapeutic vehicle — became the template for radioactive tracers across medicine, a field that still runs on the same elegant logic the thyroid accidentally suggested.