1918

Nobel Prize in Physics

Max Planck

Planck proposed in 1900 that energy is emitted in discrete packets — quanta — as a mathematical trick to make the blackbody radiation formula work. He spent years afterwards trying to explain the trick away; it proved unexplainable, because it was true. The prize arrived eighteen years later, by which time quantum mechanics had become an edifice Planck himself found deeply unsettling.

Nobel Prize in Chemistry

Fritz Haber

Haber synthesised ammonia from nitrogen and hydrogen at high pressure and temperature, enabling the large-scale manufacture of nitrogen fertiliser. The process now feeds roughly half the world. Haber also directed Germany's chemical weapons programme during the war, supervising the first large-scale chlorine gas attacks. He received the prize anyway, to the considerable displeasure of the Allied nations.

Emmy Noether proves her symmetry theorem

Noether presented her theorem on 26 July: for every continuous symmetry of a physical system there is a corresponding conserved quantity. Rotational symmetry gives angular momentum; translational symmetry gives linear momentum; time-translation symmetry gives energy. The theorem is not a result within physics — it is a result about physics, explaining why conservation laws exist at all. Noether was at this point still arguing with Göttingen for the right to give lectures under her own name.

Shapley maps the Milky Way's true structure

Harlow Shapley used Cepheid variables in globular clusters to calculate distances and found the clusters were arranged in a vast spheroid centred not on Earth but on a point some 30,000 light-years away in the direction of Sagittarius. The Sun, it followed, sits well off-centre in its own galaxy — a reassignment of address as significant, in its way, as Copernicus's.

Spanish influenza pandemic

The pandemic emerged in early 1918 and swept the world in three waves over two years, infecting perhaps a third of the global population and killing an estimated 25 to 50 million people — more than the war itself. It was unusual in killing young adults in disproportionate numbers. Its origins and the reason for its particular severity are still debated.

Nova Aquila observed

On 8 June, a star in Aquila flared to magnitude 1.4 — the brightest nova since Kepler's star of 1604 — and was briefly visible in daylight. It faded over months as the ejected shell of gas expanded outward, which is what novae do, though no one then fully knew why.