Luminiferous aether

In the late 19th century, luminiferous aether, aether or ether, meaning light-bearing aether, was the postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space, something that waves should not be able to do. The assumption of a spatial plenum of luminiferous aether, rather than a spatial vacuum, provided the theoretical medium that was required by wave theories of light.

The concept was the topic of considerable debate throughout its history, as it required the existence of an invisible and infinite material with no interaction with physical objects. As the nature of light was explored, especially in the 19th century, the physical qualities required of the aether became increasingly contradictory. By the late 1800s, the existence of the aether was being questioned, although there was no physical theory to replace it.

The negative outcome of the Michelson–Morley experiment suggested that the aether was non-existent. This led to considerable theoretical work to explain the propagation of light without an aether. A major breakthrough was the theory of relativity, which could explain why the the experiment failed to see aether, but was more broadly interpreted to suggest that it wasn't needed. The Michelson-Morley experiment, along with the blackbody radiator and photoelectric effect, was a key experiment in the development of modern physics, which includes both relativity and quantum theory, the latter of which explains the wave-like nature of light.

Neil deGrasse Tyson

Neil deGrasse Tyson (/ˈniːəl dəˈɡræs ˈtaɪsən/; born October 5, 1958) is an American astrophysicist, cosmologist, author, and science communicator. Since 1996, he has been the Frederick P. Rose Director of the Hayden Planetarium at the Rose Center for Earth and Space in New York City. The center is part of the American Museum of Natural History, where Tyson founded the Department of Astrophysics in 1997 and has been a research associate in the department since 2003.

Born in New York City, Tyson became interested in astronomy at the age of nine after a visit to the Hayden Planetarium. After graduating from the Bronx High School of Science, where he was editor-in-chief of the Physical Science Journal, he completed a bachelor's degree in physics at Harvard University in 1980. After receiving a master's degree in astronomy at the University of Texas at Austin in 1983, he earned his master's (1989) and doctorate (1991) in astrophysics at Columbia University. For the next three years, he was a postdoctoral research associate at Princeton University, and in 1994, he joined the Hayden Planetarium as a staff scientist and the Princeton faculty as a visiting research scientist and lecturer. In 1996, he became director of the planetarium and oversaw its $210-million reconstruction project, which was completed in 2000.