OT: Speed of light [was Re: Why not a Python compiler?]

Steven D'Aprano steve at REMOVE-THIS-cybersource.com.au
Thu Feb 7 00:45:14 CET 2008


On Wed, 06 Feb 2008 10:14:10 -0600, Reedick, Andrew wrote:

>> > 'c' is also the speed of light.
>> 
>> 'c' is the speed of light _in_a_vacuum_.
> 
> True.
> 
> 
>> > And since nothing can travel faster than light...
>> 
>> Nothing can travel faster than the speed of light _in_a_vacuum_.  There
>> are situtaitons where things can (and regularly do) travel faster than
>> light: http://en.wikipedia.org/wiki/Cherenkov_radiation
> 
> 
> Nope.  It propagates, not travels, faster than light.  Go ask a
> physicist to explain it.  It's odd...

Propagate, travel, what's the difference?

If you're referring to the fact that in non-vacuum, light travels more 
slowly due to frequent interactions with the particles of the medium it 
travels through, that's discussed in the Wikipedia article.

There are quite a number of superluminal (faster than light) phenomena. 
See, for example:

http://en.wikipedia.org/wiki/Slow_light
http://en.wikipedia.org/wiki/Phase_velocity
http://en.wikipedia.org/wiki/Faster-than-light

particularly the section titled: 

"Superficially FTL phenomena which do not carry information"


-- 
Steven



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