1920

Nobel Prize in Physics

Charles Edouard Guillaume

Guillaume discovered that certain nickel-steel alloys have thermal expansion coefficients close to zero — they barely change size as temperature varies. He called the most useful one Invar. The discovery made precision instruments, pendulum clocks, and measuring standards considerably more reliable, which is the sort of contribution that matters enormously in practice and earns a polite round of applause at the ceremony.

Nobel Prize in Chemistry

Walther Nernst

Nernst's heat theorem — eventually reframed as the third law of thermodynamics — states that as temperature approaches absolute zero, entropy approaches a constant minimum. The law tells chemists that you can never quite reach absolute zero, only approach it asymptotically; and it tells physicists things about what perfect order would look like, were it ever achievable.

Nobel Prize in Physiology or Medicine

August Krogh

Krogh discovered that capillaries are not passive tubes but actively open and close to regulate blood flow to tissues according to demand. A resting muscle has most of its capillaries closed; a working one opens them. The mechanism matched oxygen delivery to oxygen need with a precision that had previously seemed too convenient to be true.

Nobel Prize in Literature

Knut Hamsun

Hamsun's novel "Growth of the Soil" is the story of a man who walks into the wilderness and builds a farm from nothing — patient, plainly told, and deeply attached to the Norwegian land. The prize was given in recognition of this and a body of work that stretched back to "Hunger" in 1890. Hamsun would later collaborate with the Nazi occupation of Norway, which history has not chosen to forget.

Nobel Peace Prize

Léon Bourgeois

Bourgeois had been arguing for international arbitration and collective security since the 1890s; the League of Nations, now limping into existence, was close to what he had spent decades proposing. He accepted the prize as an old man. The organisation he helped build lasted twenty-six years before disbanding.

Rutherford predicts the neutron

Rutherford proposed in a Bakerian Lecture to the Royal Society that atomic nuclei must contain a neutral particle — one with roughly the mass of the proton but no electric charge — to account for the discrepancy between atomic mass and atomic number. He called it a neutron. Chadwick would find it in 1932.

Aston demonstrates chlorine's isotopic composition

Frederick Aston used his mass spectrograph to show that chlorine consists of two isotopes — mass 35 and mass 37 — in a ratio that averages to 35.45, explaining a molar mass that had always seemed awkwardly non-integer. It was one of the first direct demonstrations that a common element is a mixture of isotopes.

Betelgeuse's diameter measured by interferometry

On 13 December, Albert Michelson and Francis Pease fitted a 20-foot beam interferometer to the Mount Wilson 100-inch telescope and measured the angular diameter of Betelgeuse: 0.047 arcseconds. From its known distance this implied a diameter of roughly 300 million miles — large enough that, placed at the Sun's position, the star would swallow Mercury, Venus, Earth, and Mars.

First transatlantic two-way radio broadcast

On 25 July, the first confirmed two-way radio voice communication across the Atlantic was achieved between the United States and England. The technical problems solved to make it work — tuning, amplification, antenna design — were the same ones being solved simultaneously for commercial broadcasting.

Commercial radio receivers go on sale in the United States

Domestic radio sets became available to buy in American shops, coinciding with the launch of scheduled commercial broadcasting. KDKA in Pittsburgh began regular broadcasts in November. Within a few years the living-room radio would become as ordinary as the kitchen stove, and considerably more entertaining.