# Will_Pearson comments on Initiation Ceremony - Less Wrong

49 28 March 2008 08:40PM

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Comment author: 29 March 2008 06:02:06PM -1 points [-]

Incorrect, an interesting phrase... In what manner would the phrase, "c is approximately 3x10^8," be incorrect. You say it is wrong, I say it is right. Who is to decide? Could I not go and measure it, and find c in the vacuum to be approximately 3x10^8?

Why is the questioner always assumed to be correct about every bit of data given? Sure I may not pass many exams taking this attitude, but the only examiner that really matters is reality, surely? We are here to learn how to reason about the world surely, not to learn to pass exams, or other random human tests.

Comment author: 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: 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.