Critical Opalescence Theory
Explains critical opalescence using fluctuations near a liquid-gas critical point.
Albert Einstein · Year
Albert Einstein records dated 1910, drawn directly from the World History Database source collection.

Explains critical opalescence using fluctuations near a liquid-gas critical point.
Einstein and Ludwig Hopf analysed a moving oscillator interacting with random thermal radiation to investigate the conditions required for matter and radiation to reach statistical equilibrium.
Presents the principle of relativity and its consequences for modern physics to a wider European audience in a substantial French-language review.
Einstein and Hopf examined how random radiation forces continually alter an oscillator's momentum while dissipative drag acts in the opposite direction.
In the Einstein-Hopff treatment, motion through a thermal radiation field produced a friction-like drag on an oscillator, linking electromagnetic fluctuations with Brownian-style dynamics.
The Einstein-Hopff analysis tested whether classical interactions between oscillators and radiation could reproduce a consistent equilibrium spectrum, revealing limitations of a purely classical treatment.