It doesn’t have a corresponding wavelength in the spectrum of visible light, but as we perceive it to be there and have a name for it, it doesn’t really matter that there’s no specific wavelength it corresponds to.
By that metric abstract things likely love, justice, duty, honour, could be argued to not be real either. Can’t touch them or there’s no corresponding physical thing in the world to measure them.
It doesn’t have a corresponding wavelength in the spectrum of visible light, but as we perceive it to be there and have a name for it, it doesn’t really matter that there’s no specific wavelength it corresponds to.
By that metric abstract things likely love, justice, duty, honour, could be argued to not be real either. Can’t touch them or there’s no corresponding physical thing in the world to measure them.