For the scattered light to be distinguishable from the background radiation, the photon's energy must be much greater than the mean energy of the blackbody spectrum (ℏν ≫ kT).

Szilard's argument was developed further after Shannon identified that the measure p ln p had operational significance for information theory, suggestive of a deeper connection between entropy and information. To illustrate the idea further, both Gabor (1964) and Brillouin (1951) constructed specific models of dissipative measurement that involve shining a light into one side of the engine to see whether that side contains the molecule. The light is scattered if the molecule is on that side, but