The dark matter is between their ears! The reason for the ever expanding universe is a defect in the speed of light. It slows up over distances and therefore creates the illusion of more rapidly expansion. This is a lot more reasonable explanation than “dark energy” clouds outside of our observable universe. Come on! Einstein theorized that light can be bent by gravity and that was subsequently proven. I hold that if gravity can bend it then gravity can slow it.
“I hold that if gravity can bend it then gravity can slow it.”
My understanding is that photons never slow down, they just lose energy going “uphill” in a gravitational field. Losing energy means the wavelength gets longer: e.g. visible light shifts towards red, X-rays shift towards UV, etc.
(And of course the opposite when going “downhill”.)