physics-history

In 1932, Carl Anderson photographed a positron in a cloud chamber — the first antiparticle ever detected, confirming Dirac's 1928 relativistic quantum theory and opening the field of antimatter physics.

In 1896, Henri Becquerel accidentally discovered radioactivity when uranium salts fogged a wrapped photographic plate in the dark. Learn the full story of what happened next.

Henry Cavendish measured Earth's density in 1798 using a torsion balance. Learn the apparatus, the G mystery, and why gravity's constant is still poorly known today.

In 1932, James Chadwick proved the neutron exists in just 10 days of experiments using polonium, beryllium, and paraffin wax. Learn exactly how he did it.

In 1897, J.J. Thomson proved cathode rays are particles 1,800 times lighter than hydrogen. Learn how his cathode ray tube experiment discovered the electron.