Modern astronomy use red-shift to calculate the speed with which distant bodies move, and since all distant objects display a red-shift, the conclusion is that our universe is expanding.
However, there are other ways to interpret red-shift in which a different conclusion can be reached.
The tired light hypothesis is one such interpretation. It attributes red-shift to a loss of energy by photons travelling across vast distances. The idea is that photons brush along dust and atoms on their way across the universe. They yield a tiny bit of energy to the environment they travel through.
The photons loose energy. As a result, they become redder.
The objection to this idea is that dust and atoms are so large that they will cause scatter. The fact that images from distant objects are sharp and crisp exclude the possibility of energy loss to such large particles.
However, if our universe is full of zero-point particles, then scatter is no longer a problem. Zero-point photons are too small to cause the much larger visible photons to scatter. But they will be receptive to a tiny bit of energy transfer.
The red-shift observed in astronomy may not after all be due to an expanding universe. It may instead be due to an aether of zero-point particles.
The background radiation attributed to the big bang may in turn be nothing but zero-point photons heated enough by visible light to give the universe a uniform glow.
If so, we no longer need to invoke a big bang or an expanding universe to explain the observed red-shift and background radiation. It can all be explained by the zero-point aether.