Subject: thermodynamics and dark energy
I may need some time to digest this. Very interesting.

https://phys.org/news/2024-04-...

The authors show, using the Grüneisen parameter, that continuous cooling of the universe is associated with a barocaloric effect that relates pressure and temperature and occurs owing to adiabatic expansion of the universe. On this basis, they propose that the Grüneisen parameter is time-dependent in the dark energy-dominated era (the current universe era).