# Is there a finite number of colors in the visible spectrum? [duplicate]

Does quantum theory and Planck's length of $$1.6\times10^{-35}\ \mathrm{m}$$ mean that the electromagnetic spectrum is not continuous as every photon can only carry a discrete amount of energy?

If so, wouldn't that mean that a light spectrum with an upper and lower limit such as the visible light to us humans has a finite number of colors?

I know that photons get their wavelengths from the particles they are emitted from, but couldn't we say for example that the spectrum of visible light between $$380$$ and $$750\ \mathrm{nm}$$ is $$370\ \mathrm{nm}$$ long and divide by the minimal length of causality that would be Planck's length there no more than roughly $$2.3\times 10^{28}$$ possible wavelengths and therefore colors in the visible spectrum?

• Why do you think Planck units are any kind of rigorous limits? They aren’t. May 31 at 16:29
• Possible duplicates: physics.stackexchange.com/q/169209/2451 and links therein. May 31 at 17:12
• The energy and thus the frequency of a photon in an infinite space is not quantized into a discrete set. The allowed energies form a continuum. This is true of any free particle. Whether this continuum has a cutoff around the Planck energy, or doesn’t, is irrelevant. May 31 at 22:09
• You seem to be thinking that the Planck energy is some kind of minimum energy, so that all possible energies are multiples of the Planck energy. This is wrong, and basically backwards; it may (or may not) be some kind of maximum energy for elementary particles. May 31 at 22:13