The diffraction limit, the smallest angle in degrees that can be resolved, is 250,000 arcsec × (wavelength/diameter of telescope). Humans have two eyes separated by about 6.9 cm and a marvelous computer between their ears. If this optical interferometer is just as good as one eyeball and as large as the separation of two regular eyeballs, what is the diffraction limit in arcsec of human vision for visible light at 643 nm?
