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bigjeff5 comments on Initiation Ceremony - Less Wrong

49 Post author: Eliezer_Yudkowsky 28 March 2008 08:40PM

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Comment author: bigjeff5 03 February 2011 12:33:26AM *  0 points [-]

C is only roughly 3x10^8 meters per second when traveling in a vacuum. Any interaction with matter slows it down, though usually only very slightly.

I believe the slowest light has ever been measured is 38mph (15.6 meters per second), achieved by firing a laser through sodium atoms held in a Bose-Einstein condensate (0.37 degrees Kelvin).

Pretty impressive, really.

In other words, the "if" statements are extremely important.

Comment author: pnrjulius 09 April 2012 06:20:35AM 2 points [-]

c is by definition the speed of light in vacuum. You use another variable (usually v) if you want the speed of light in a given refractive medium.