How are different photon wavelengths explained with String Theory? From what I understand, a photon is a string with a particular configuration. Are all photon strings identical? There are photons in the IR spectrum with very long wavelengths, like the length of a city or even longer, but I don't know how particle wavelengths connect to strings in String Theory. Thanks.
You can factorize the wavefunction of a single free string, into a wavefunction for the position of the center of mass, and a wavefunction for the excitations of the string relative to its center of mass. Wavelength of a single-particle wavefunction, corresponds to wavelength of the center-of-mass component of the string wavefunction.