Richard Clark wrote:
"This paradox (differing light intensities in various directions) was
solved by?"

I have not seen that question before, but will speculate that Edwin
Hubble deserves the credit as he used "red shift" in the light from
other galaxies to show that they are speeding away from us and our
galaxy. In fact, they are accelerating so that the farther the galaxy is
away from us, the faster it is moving away.

From continuous acceleration, the distant galaxy will eventually reach
the speed of light. Then, light from the distsnt galaxy won`t reach us
because it will tag along with the fast moving galaxy.

There may be a time shortage too as Einstein has shown time slows as a
thing moves faster.

Hubble has also shown that the Doppler effect would shift the frequency
lower as velocity of the retreating thing increases. Shift the frequency
low enough and the wave is no longer described as light but may be
classified as a millimeter radio wave.

Best regards, Richard Harrison, KB5WZI