Comment by bnetd
3 days ago
As an aside, is there conclusive evidence to say that no aether exists, or are we just saying it doesn't exist because a handful of tests were conducted to match what we thought this aether would behave like and the tests came back negative?
Lorentz formulated his ideas in terms of a motionless aether. But his aether theory yielded predictions identical to special relativity, so later physicists ditched his interpretation in favor of Einstein's theory that didn't need an undetectable global reference frame.
Overall, we can't really have 'conclusive evidence' against any mechanism, as long as our observations might possibly be simulated on top of that mechanism. So as far as evidence goes, 'what really exists' might be higher-dimensional strings, or cellular automata, or turtles all the way down, or whatever.
Instead, physics has some number of models (either complementary or competing) that people find compelling, and mechanisms on top of those models to explain our observations. If you did come up with a modern aether theory, you'd have to come up with a mechanism on top of it to explain all the relativistic effects we've observed.
We say the "aether" as it was originally conceptualized in the 19th century doesn't exist for the same reason we say that Russell's teapot or Carl Sagan's invisible dragon in the garage doesn't exist: we have a model of the world that makes all the same predictions without it, so it gets scraped right off by Occam's Razor.
For a strict enough definition of "conclusive," there is never conclusive evidence that something doesn't exist.
On top of that, if we find something that behaves nothing like what people meant when they said aether, then is it really aether?
You can call spacetime "aether" if you prefer - Einstein himself did. It's just that it becomes redundant at that point.
If electromagnetic radiation is propagating through some medium, then that medium is at rest with respect to all inertial reference frames simultaneously.
It's simpler not to have a medium. The field components transform a certain way under coordinate transformations, and that's all you need.
https://samzdat.com/2018/05/31/science-cannot-count-to-red-t...
Magnetic field is that aether.