Energy · 1938

Nuclear fission

Uranium nuclei split under neutron bombardment, releasing enormous energy.

Otto Hahn and Fritz Strassmann detected barium from neutron-bombarded uranium in December 1938, and Lise Meitner and Otto Frisch explained it as fission. Each fission frees about 200 MeV, millions of times more than a chemical reaction.

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 4

Neutron 1932
Quantum mechanics 1925
Special relativity 1905
Radioactivity 1896

What it led to 2

Nuclear reactor 1942
First thermonuclear fusion 1952

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