retropathy 

A pathological yearning to go back in time.

He had squandered his youth and was now beset by retropathy, needing to do it again and do it better. He would quit his job, find his first car and buy it back, find his old girlfriend and they'd hit the road. He'd wake up one morning and be twenty again. He was sure of it.

retropathy by Monkey's Dad October 30, 2021

Retrophysics

The umbrella term for any branch of physics that describes phenomena as they would appear if time ran backward. It encompasses retrothermodynamics, retromechanics, retroentropy—the whole suite of physical laws operating in reverse chronological order. Retrophysics is a powerful tool for thought experiments, helping physicists understand why certain processes are irreversible even when the underlying equations are time-symmetric. It's the physics of the rewound tape, the universe played backward, the cosmic movie running from credits to opening scene.

Example: "The professor assigned a retrophysics problem: calculate what the solar system would look like if we ran the equations backward for a billion years."

Retrophysics by Dumu The Void March 11, 2026