I am confused about the physical meaning of the redshift. Let say the non-relativistic one z=v/c. When I read Barbara Ryden, Intro to cosmology, she demonstrate the z is not related to the space expansion between the source and the receiver, but 'it does tell us what the scale factor was at the time the light from the galaxy was emitted'. When I read J.E. Lidsey, ASTM108/PHY7010U Cosmology, he syas that 'the time taken to be emitted is t=Lamda-emitted/c' and during that time for a stationary observer the source will move a distance vt, which adds to the wave lenght. From that we can obtain (I understand co-move) Lamda-observed=Lamda-emitted+vt, and derive Lamda-Obs/Lamda-Em = 1 + v/c. My questions are: 1) is the extension of the wavelenght a local action only during the time of emission caused by the co-movement, and therefore independently from the distance of far away observers? 2) if it is independent of the far away observers, i.e., receivers, and independent of the space expansion in between the source and the receiver, all observers should measure the same emitted wavelength because once the photon is emitted it is not transformed anymore. Thank you.