Math & science · 1932

Neutron

Chadwick identifies the neutral particle in the nucleus.

The neutron explained isotopes and, being uncharged, could penetrate nuclei. Fermi used it to transmute elements, leading directly to the discovery of fission in 1938.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 1

Atomic nucleus 1911

What it led to 4

Nuclear fission 1938
Nuclear reactor 1942
Big Bang nucleosynthesis 1948
Radiocarbon dating 1949

Related measurements

The dashed line marks when it first worked.

Nuclear electricity generation Latest: 2.81k TWh (2025) Source: Our World in Data

World primary energy by source Latest: 178k TWh (2025) Source: Our World in Data