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A comment on Home experiments to derive the speed of light?.

Re:Home experiments to derive the speed of light? by chemmail on Thursday October 13, 2011 @08:04PM (#3109338)
Wouldn't the face that you cannot achieve a perfect vacuum make measuring the true speed of light to exactly c impossible?
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Re:Home experiments to derive the speed of light? by mjb on Thursday October 13, 2011 @08:48PM (#3109451)
Not really, no. The speed of light in air is very nearly identical to the speed of light in a vacuum. Wikipedia gives the refractive index of air as 1.0003, which is the ratio between the speed of light in a vacuum and the speed of light in air.

The use of air as a medium rather than a vacuum is unlikely to be a significant source of error in an amateur measurement of c.

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