The Tired Light Hypothesis

The tired light hypothesis was proposed as an alternative to the expanding universe hypothesis.

The idea was that light would loose energy over time. Distant things would then appear redder than closer things because of the energy loss.

However, in the absence of an ether, energy loss would mostly be due to dust and similarly large particles. This would produce much more scatter than we observe. Distant things should appear fuzzy and unfocused. That's not the case.

But if there is an ether, then energy loss might very well happen without any scatter. Physic theories that invoke the existence of the ether are in other words indirectly supporting the tired light hypothesis. It does not necessarily follow that the tired light hypothesis must be right if there is an ether, but it would add a great deal of weight in its favor.