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A comment on Scientists Capture a “Sonic Boom” of Light. Parent comment

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.
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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.

https://en.wikipedia.org/wiki/Impedance_of_free_space

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Re:Scientists Capture a “Sonic Boom” of Light by passwd on Wednesday January 25, 2017 @06:15AM (#13480467)
>Free space has an electrical resistance of about 376 ohms.

Impedance, to be precise. If free space had electrical resistance of 376 ohms, our world would be much stranger place than it is now.

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