🔬 Discovery

Stjepan Mohorovičić's prediction of the 'electrum' (electron-positron atom)

Predicción del «electrum» (átomo electrón-positrón) de Stjepan Mohorovičić

Date
1934 · confidence medium
Place
Zagreb, Croatia
Credited to
Stjepan Mohorovičić
Field
Cosmos & Earth

⚠️ Disputed: the sources disagree.

What was discovered

In 1934 he proposed the existence of a bound system of electron and positron, which he called 'electrum' and studied for its spectrum. It is what is now called positronium.

Stjepan was the son of Andrija Mohorovičić. Martin Deutsch observed positronium in 1951 and coined the name; Mohorovičić's proposal had little echo and was linked to the 'electrum' name only retrospectively. Ruark (1945) and Pirenne (1944) also made estimates.

What it led to

  • study of positronium as a quantum electrodynamics system
  • use of positronium in materials physics
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Sources✓ verified 2026-11-04