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From: bl@hplabsb.UUCP
Newsgroups: net.startrek
Subject: Re: Speed of light
Message-ID: <3139@hplabsb.UUCP>
Date: Thu, 31-Oct-85 12:54:43 EST
Article-I.D.: hplabsb.3139
Posted: Thu Oct 31 12:54:43 1985
Date-Received: Fri, 1-Nov-85 22:23:51 EST
References: <353@uw-june.UUCP> <8500013@orstcs.UUCP> <198@ur-tut.UUCP>
Distribution: net
Organization: Hewlett Packard Labs, Palo Alto CA
Lines: 19

> In article <8500013@orstcs.UUCP> jamesp@orstcs.UUCP (jamesp) writes:
> >This is called "Cherenkov Radiation,"  and happens all the time.  Often a
> >subatomic particle is moving faster than the speed of light in a medium (for
> >example, the speed of light in water is much less than the speed of light in a
> >vacuum -- ever seen a picture of a nuclear reactor with that beautiful
> >sky-blue "radioactive" glow?  That's caused by lots of alpha and beta
> >particles ripping through the water faster than the speed of light.)
> 
> WHAT???  The speed of light in water is much less than the speed of light 
> in a vacuum????  AAAUUUGHH!!  Einstein just rolled over!  I always thought:
> 'The speed of light is the same for all observers, no matter what his 
> frame of reference'...  If what you say is true, then all kinds of phenomena
> would open up simply by exceeding this 'slower' speed in water...  Eek! 

Have you ever used a lens?  Have you ever seen a prism produce a spectrum?
The principle of refraction works because of the difference in the speed
of light through the lens medium (glass in this case) and the surrounding
medium (air in this case).  Light sure does travel slower through denser
mediums, including water.