I have been reading a little bit on these forums about the red car myth. It appears most of you are claiming that its only apparent because red is a more noticeable color than any other standard color.

I have a hypothesis about the myth and I think it would be a pretty cool experiment. Though I haven't done a whole lot of research on the subject, I do know a little bit about spectra, doppler, and EM Radiation.

Okay, here goes. The color red is known to have a longer wavelength than all of the other colors in the visible spectrum. And thus when you see a redshift, in astronomy, it will me associated with an object in space moving away from us because of the Doppler red-shift. My hypothesis is simply that when a police radar gun reflects the radio wave from a red car, the red paint of the car will actually reflect a longer wavelength back to the radar gun than, say, a blue car would. this slight shift might actually cause a faulty, and possibly faster, reading than the car was actually traveling. This is of course for cars that are traveling away from the radar beam

In my opinion this would make for a good episode because we could get a lot of fast cars and run them down the road at different speeds to test the different effects of each color on the radar gun.

*Note. None of my assumptions are actually researched thoroughly. Paint that would cause a red color in the visible spectrum might not even effect a radar beam, I just saw a reoccurring myth and thought I'd throw something out there to discuss.

The Doppler shift has nothing to do with the colour of the paint. Either the car reflects radio waves of that frequency or it doesn't.

If the radio waves are red-shifted, then the car is moving away from the RADAR unit, and if they are blue-shifted then the car is approaching.

Although obviously when I use "red-shifted" and "blue-shifted" I'm only trying to imply the direction of the change in frequency since the radio waves aren't visible to begin with.

quote:

The Doppler shift has nothing to do with the colour of the paint.

I wasn't suggesting it was either. I didn't say that the paint was creating a Doppler shift. I only suggested that the red paint is possibly re-emitting longer radar waves than other paint.

I only used the Doppler effect as an example to show that red (redshift) is associated with longer visible waves.