Ether has long been used for explaining the propagation of light. Aristotle discussed Ether. Given electromagnetic waves, the implication that light has to propagate through something seemed reasonable. Ether went the way of phlogiston and caloric when Michelson and Morley split a light beam, then bounced the two perpendicular rays back to each other and found no difference in diffraction. If it can’t be measured then forget about it.
The Dark Matter theory accounts for the difference between observed mass and the behavior of galaxies by positing an entity that exists in a vacuum yet has mass. Dark Matter seems a misnomer as it allows for the transmission of light. Exists in a vacuum, has mass and propagates light, sounds like Ether to me.
Abandoning Ether leads to the wave particle duality and quantum theories. Why is it that a child without any apparent ability of concentration or interest can intently spend their entire playground time pouring sand through a sieve? The very purposeless futility of it provides its own satisfaction. This tremendous sense of stasis is the most terrifying human quality. When one examines failed theories it is tempting to think that there should be some intuitive way to determine correctness. This thinking, argument by metaphor, drives scientists’ nuts. There are people who are always wrong and love senseless activity. I have sympathy for the other child who walks over and hits the first one with a toy shovel. If you must talk Alternate Universe, you should not disparage Ether.
Mass without volume seems nonsense, mini black holes? Until you examine the other theories.
Another bizarre theory is explaining the red shift with expanding universe.
Occasionally we look up and see the sun and the moon together in the sky. We can see that the two bodies are round and that the sun reflects off the moon. Why did this seem mysterious? Until we observe that the sun’s reflection on the moon does not correspond to the sun’s position in the sky. How did we figure out anything? Nature is duplicitous.
Ether or no, gravity bends light. The light of our observations has been through innumerable gravity events, culminating with being drawn in by our own sun. Such observations deserve skepticism. Or Ether causes the red shift.
Recently the Michelson/Morley experiment has been extended to discover gravity waves. An extremely large and sensitive instrument, it chattered. Two of them were built to compare the results. Eventually the expected badumbump of the gravity wave occurred on both instruments. But when the results were examined it was found that the chatter matched as well. Perhaps the chatter is a consequence of distant dissipated gravity waves, or Ether.