Hello all, so I've always wondered about the expansion of the universe as indicated by the observed doppler (red) shift... i get the observed spectrum change and how this can be credited to the stretching of electromagnetic waves... what doesn't make sense to me is that if this is due to a 'stretching' of space-time, or distance itself is expanding, then this should be undetectable from within the universe. ie. if the wavelength of EMR is say 1m, but then the 'fabric of space' is stretched which in turn stretches the EM wave(and gives the observed increase in wavelength), we should see no change as 1m is still 1m... if the wave is traveling at a constant C, then the effect of 'stretching' distance makes no difference, the wave should still cover the entire 1m length in a given time, otherwise either the wave has slowed to below C, or extra space has been added and you now have more than 1m. Im having trouble explaining my thinking in text and can visualize it better kind of like in a warped mirror you see at a carnival, you can only see the warping effect from the outside - inside the mirror all the ratios are the same and you won't notice any amount of stretching/compression. can anyone get my meaning and explain it to me? cheers!