Re: if you could relate the spectrum to sound what notes would be what color?

Hi Gerard,

This is of course like comparing apples with bicycles. Visible Light is part of the electromagenetic spectrum, electromagnetic radiation consists of an electric and a magnetic field, 90 degrees apart, both creating the other and propagating "at the speed of light" through space at(300,000,000 metres/sec in vacuum) Sound is a purely mechanical phenomenon of conduction through gases and solids, at much lower speeds. Sound travels at roughly 300 m/s in air, though in solids it can travel quite a bit faster, it cannot approach the speed of light.

In the most basic physics however, we relate the frequency of light and its wavelength to its speed by the relationship v=nL, where v is the speed of propagation, n is the frequency and L is the wavelength.

Humans can see and hear only a very narrow range of both em spectrum and sound, we can see from roughly 390nm to 750 nm and that is the full range of colours we can experiencs, from deeeeep violet to deeeeeepst red. In sound terms we can "hear" from 20 Hz to 20Khz, if we are younger than about 25 and/or lucky. (the older you get the less high frequencies you can hear)

While you can make a whimsical case that 750nm corresponds to 20 Hz and 390 nm to 20Khz, the analogy breaks down very rapidly, as a whole range of phenomenon with sound vary wildly within the audible range, but those of light do not: here I am thinking of diffraction of sound.

This "equivalence" has nothing at all to do with relativity.

Steve