In 1880, scientist Albert Michelson set out to build a device to measure something every 19th century physicist knew just had to be there. The “luminiferous ether” was invisible and pervaded all of space. It helped explain how light traveled, and how electromagnetic waves waved. Ether theory even underpinned Maxwell’s famous equations! One problem: When Alfred Michaelson ran his machine, the ether wasn’t there.  Science historian David Kaiser walks Annie and Science Friday host Ira Flatow through Michaelson’s famous experiment, and explains how a wrong idea led to some very real scientific breakthroughs. This story first aired on Science Friday.   GUEST David Kaiser, Germeshausen Professor of the History of Science, Professor of Physics, the Massachusetts Institute of Technology   FOOTNOTES Find out more about the Michelson-Morley experiment on APS Physics.  Read an archival article from the New York Times about the physicists’ experimental “failure.”   CREDITS This episode of Undiscovered was produced by Annie Minoff and Christopher Intagliata. Our theme music is by I Am Robot And Proud.