The speed of light they are referencing is the speed of light IN A VACUUM. We’ve known for some time that the velocity can be changed in different media. They chose to use a plasma and measure there.
The speed of light they are referencing is the speed of light IN A VACUUM. We’ve known for some time that the velocity can be changed in different media. They chose to use a plasma and measure there.
https://www.physicscentral.com/explore/action/light.cfm
http://ffden-2.phys.uaf.edu/webproj/211_fall_2014/Serena_McCormick/147439795548ea5113f13a/bose-einstein-condensate.html
(post is archived)