Re:Scientists Capture a “Sonic Boom” of Light
by ianai on Tuesday January 24, 2017 @02:33AM
(#13469500)
Light always travels at c. It may appear to an observer to travel slower than c if it is being absorbed and emitted through media along the way.
Re:Scientists Capture a “Sonic Boom” of Light
by snarfy on Tuesday January 24, 2017 @10:05AM
(#13471834)
It's not due to absorption/re-emission. The vacuum permittivity and permeability of free space is different than a medium.
https://en.wikipedia.org/wiki/Vacuum_permittivity
https://en.wikipedia.org/wiki/Vacuum_permeability
Free space has an electrical resistance of about 376 ohms.
What they're doing here is based on the fact that you can make light move at under c if you force it to travel through a dielectric material. The c in E=mc^2 is the speed of light in a vacuum: not necessarily through a carefully designed atomic obstacle course.