Value of Speed of Light (of starlight in outer space)
Light of two stars coming from the left and right is passing through a glass cube. This cube is floating horizontally in outer space. Inside the glass, formula c/n = f λ holds. Four values are known.
Two lights inside the glass are spectralized and the spectra (distance between chosen atom or molecule A and B) is compared. The two will be slightly different.
Note) For light in outer space, formula v = f λ holds. And value f is the same as f for the glass (from the perspective of the glass).
