Is this course of basic physics or NANOG mailing list ????

65% the speed of light in a vacuum ?

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The equivalent EMR propagation speed in coppr is 0.75c

What is EMR?

Electo-Magnetic Radiation. Electrons don't count as EMR do they though, (hell they have a mass!) so data in the form we transmit it down copper won't move at this speed will it?

True, electrons have mass, but we are not 'transmitting' electrons. We are oscilating the electrons in the media. This oscilation creats EM energy which propogates down the media, in the form of photos, and will propogate at some percentage of c depending upon the media.