Collected cathode rays in Faraday cup electrometer, proving negative charge.

Discovered natural spontaneous radioactivity in uranium salts using photographic plates.

Discovered magnetic splitting of spectral lines into triplets in strong magnetic fields.

Calculated e/m ratio of bound electrons from Zeeman splitting, confirming electron theory.

Published Wien's spectral energy distribution equation for blackbody cavity radiation.

Published first quantitative climate model calculating global warming from CO2 absorption.