I had a look at the recalculation site but the slight problem is if there is uniform expansion then the photon energy would map differently to expanded matter.

Wouldn't the need for a recalculation be if the rate of expansion of space and of matter were increasing (or changing) in a non linear fashion?

To explain the first line if matter was increasing and yet staying uniform as we feel it the space for the electron to jump would grow and require more than the current 4*10^-19 ev to raise an electron to activate a photon receptor.

Perhaps by sliding along the scale the unique spectral lines would appear in a different part of the visible light range in a non linear shift which could be a red shift indicator because the natural thing to do here on earth as we receive light would be to apply the known spectrum of light and see the change in position of the lines of absorption.

Again it is off the top of my head so if I am wrong please feel free to correct me regarding size change and electron volt energy requirements. But that is what I would probably do ... assume light is the same as light produced here on earth and map against line of spectral absorption if I hadn't realised it was the actual spectrum that was changing due to energy requirements for a photon to excite an electron to higher orbit.

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"Nature is obliged to let reality determine its laws, whereas mathematics is under no such constraint."