The above quote is from another thread about a month ago, so i started another thread.

As above...red light about 600 nanometers, blue light about 400 nanometers, so what could the smallest possible wavelength of light be or is it infinely small?

or the longest possible wavelength for that matter

You might say that the smallest wavelength possible would be http://en.wikipedia.org/wiki/Planck_length" [Broken] (1.616e-35 metres) which is the smallest distance predicted before quantum effects reduce spacetime to a quantum foam.

Possibly the longest wavelength of light can be associated with a zero-point energy, but the smallest wavelength of light is associated with the highest energy possible in one photon. These are probably limited by Quantum Mechanics, though I'm not sure.

The highest and lowest wavelengths are, naively, as close to infinity and zero as possible, disregarding quantum effects. These can occur as you get red/blue shifted and as you get closer and closer to the speed of light. We can see that from the relativistic doppler shift:
[tex]\lambda_0=\sqrt{\frac{1+\frac{v}{c}}{1-\frac{v}{c}}}\lambda_s[/tex]
Although since you can never achieve the speed of light the wavelengths will never achieve infinity or zero.