Question About the Universe

You need to think of this in terms of quantum mechanics. The probability wave of the photon doesn't collapse until it is observed. Once the photon is observed only then can you make sense of it's path. IOW, it doesn't make sense to talk about space expanding behind the light.The speed of light is not a law. It is THE law. All observations change in order to keep this law in place. This is why you get redshift. The frequency of the light changes so that the velocity of light and the energy of light is conserved. The way in which you observe the passage of time and distance all change in order keep the observed velocity of light the same.

To be fair, this is still controversial. The following paper does show that cosmological expansion can be treated as a Doppler shift with the subsequent conservation of energy: LinkHowever, they do state that:

quote:

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As a result, it is widely accepted that energy is not locally conserved in general relativity3, although claims are made that energy is globally conserved during expansion. This is in stark contrast to the normal Doppler shift where, as demonstrated in the text, energy is conserved on a photon-by-photon basis.

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So I am not correct in stating that energy MUST be conserved. However, I am pretty sure that the velocity of light is conserved.