About: http://webisa.webdatacommons.org/269117845

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	In some very interesting cases, the speed of light is much less than the speed of light in vacuum, notably the few meters/second speed of light achieved in a particular kind of atomic vapor a few years ago.
http://www.w3.org/ns/prov#wasQuotedFrom	macobserver.com