"There’s some kind of gas or some thermal system out there that we can’t see directly" - The Ether is back on the menu boys
What Causes Gravitational Time Dilation? A Physical Explanation.
https://www.youtube.com/watch?v=DjwQsKMh2v8
I like the river model which helps with the intuition.
It has been back for a while in the form of quantum fields.
95% of the Universe is made up of dark matter and dark energy. These are words astronomers have come up with to give a name to the mysterious, invisible side of the Universe
Caloric. Dark matter. Cosmological constant.
We like placeholders for the unknown.