… weighing in at nil, the aether!

Skulls in the Stars: Lord Rayleigh vs. the Aether! (1902)

One of the most fascinating aspects of 19th century physics is that many remarkable ideas and ingenious experiments were motivated by a physical hypothesis which we now know to be incorrect: namely, the aether. When light was demonstrated to have wavelike properties in the early 1800s, it was natural to reason that, like other types of waves, light must result from the excitation of some medium: after all, water waves arise from the oscillations of water, sound waves arise from the oscillation of air, and string vibrations are of course the oscillations of string. The hypothetical medium which carries light vibrations was dubbed the “aether”, due to its unknown, “aetherial” nature.