In the late 1800s, no one knew what light was. Everyone knew it behaved like a wave some of the time, but all waves need to travel through some propagation medium. This propagation medium was called ...

As the 19th century came to a close, physicists were feeling pretty satisfied with the state of their science. The great edifice of physical theory seemed complete. A few minor experiments remained to ...

Brendan Foster describes renewed interest in the luminiferous aether (2 November, p 32). For all its shortcomings, the aether was one of the most productive scientific ideas of all time. Many ...