"About 95 percent of the mass of our galaxy is invisible and does not interact with light. It is made of a mysterious substance called dark matter, which has never been directly measured."
https://www.nasa.gov/feature/how-dark-matter-could-be-measured-in-the-solar-system
"An astrophysicist and cosmologist Dr. Farnes published a paper while at Oxford University with a novel explanation for dark energy and dark matter. His theory claims to explain the missing 95% of the observable universe by the existence of "dark fluid"."
https://bigthink.com/hard-science/astrophysicist-dark-fluid-missing-95-percent-universe/
"It’s hard to believe, but the idea that the Universe was dominated not by normal matter but rather by dark matter — a novel form of non-interacting matter that’s completely distinct from protons, neutrons, and electrons — goes all the way back to 1933. For decades, the overwhelming majority of the leading astronomers and physicists dismissed the idea as being ill-motivated, and it gained very little traction on both the theoretical and observational fronts throughout the ‘30s, ‘40s, ‘50s and ‘60s. It was only with the novel results and improved instrumentation initially leveraged by Vera Rubin and Kent Ford, and then further developed by Rubin on her own, that dark matter was brought into the cosmological mainstream in the 1970s."
https://www.forbes.com/sites/startswithabang/2021/08/24/who-really-discovered-dark-matter-fritz-zwicky-or-vera-rubin/?sh=2185826217a7
"The aether exists and it is the medium for propagating light and other longitudinal and transverse (electromagnetic) waves across the universe. It is the fabric of our universe, consisting of tiny granules that transfer energy in the form of waves. Its structure and properties were worked out in the section on spacetime. In fact, it has a density property in the wave constants that appears in all of the energy wave equations. Without an aether, or without this density property, none of the calculations performed in this theory would be possible."
https://energywavetheory.com/explanations/aether/
"ether, also spelled aether, also called luminiferous ether, in physics, a theoretical universal substance believed during the 19th century to act as the medium for transmission of electromagnetic waves (e.g., light and X-rays), much as sound waves are transmitted by elastic media such as air. The ether was assumed to be weightless, transparent, frictionless, undetectable chemically or physically, and literally permeating all matter and space."
https://www.britannica.com/science/ether-theoretical-substance
The Universe: Mysterious Dark Matter Explained (S2, E6) | Full Episode | History