Points for you if you already understand this physics-based bumper sticker. The effect is called blue shift. From Wikipedia:
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Blue shift is the shortening of a transmitted signal's wavelength, and/or an increase in its frequency, due to the Doppler Effect, which indicates that the object is moving toward the observer. The name comes from the fact that the shorter-wavelength end of the optical spectrum is the blue (or violet) end, hence, when visible light is compacted in wavelength, it is shifted towards the "blue" end of the spectrum. Since the longer-wavelength end of the visible electromagnetic spectrum is red, the opposite effect, of a lengthening of a signal's wavelength, is referred to as redshifting.
While the terms "redshifting" and "blueshifting" imply significantly redder or bluer light, only the most distant galaxies and those moving at speeds far above average emit light that arrives with perceptible red or blue tinges. For the most part, shifting is not a visible phenomenon.[1]
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#2 If you can read Cr2O3 you are too close.(That's for my chemist friends) :p
All we needed to see was the sticker. If we got the joke we laughed, if we needed it explaining we were never going to laugh.
For some of us who haven't been in a physics class in twenty years... it was funny because I kinda got it... but it was nice to have a quick refresher on the science.
So I disagree with your conclusion. I did laugh! But I appreciated the explanation also.
and josh;
The wavelength gets shorter if the two cars get nearer to each other, just like the pitch of sound going up when something moves towards you. (and blue is shorter, allthough sillyspeed would be needed..)
so you are driving too fast, or I'm driving too slow...
or; If this sticker is infra-red, I'm driving too fast
but we're way past funny now, I guess