Langley invents the ultra-sensitive thermal bolometer, measuring infrared solar and blackbody spectra.

Demonstrated cathode ray magnetic deflection, shadow casting, and momentum in Crookes tubes.

Boltzmann formulates statistical entropy S = k log W and introduces discrete energy states into …

Introduced discrete energy elements epsilon into combinatorics to calculate probability.

Derived S = k_B log W connecting thermodynamic entropy directly to microstate multiplicity.

Goldstein investigates electric discharge in glass vacuum tubes, naming cathode rays (Kathodenstrahlen).

Derived the Phase Rule (F = C - P + 2) governing multi-phase chemical equilibrium.

Initiated experimental investigations into spark gap electric discharge phenomena.

Established transverse wave optics foundation for electromagnetic field theory.