Retrocausality

A hypothetical phenomenon where effects precede their causes—where the future influences the past, rather than the other way around. Retrocausality challenges our most fundamental intuition about time: that cause always comes before effect. In retrocausal scenarios, an event in the present could be caused by something in the future; decisions yet to be made could shape history already written. While this sounds like science fiction, certain interpretations of quantum mechanics (the transactional interpretation, Wheeler's delayed-choice experiments) hint that retrocausality might be real at the quantum level. Particles seem to "decide" their past based on future measurements. Retrocausality asks: what if time's arrow is not as fixed as we think? What if the future is already influencing the present, and we just can't see it?

"The particle's path changed based on a measurement that hadn't happened yet—as if the future reached back and told the past what to do. Retrocausality: effects before causes, future shaping past. Quantum mechanics hints at it; logic recoils from it. But nature doesn't care about our logic. Maybe time flows both ways, and we're just too slow to notice."

by Dumuabzu March 6, 2026

Retroentropy

The unsettling feeling that order isn't moving forward, but backward. It’s the perception that systems are becoming more organized into a state that is functionally worse, more chaotic, or more oppressive. While regular entropy measures the trend toward disorder, retroentropy describes a universe where things are snapping into a horrifyingly rigid, but ultimately more useless, form of order. It’s the feeling that your computer's files aren't just getting scrambled, but are rearranging themselves into a perfect, unopenable, and menacing grid.

Example: "My room was a mess, but after my mom 'cleaned' it, I can't find anything. It’s not entropy, it’s retroentropy—a perfectly organized chaos that serves no one."

by Dumu The Void March 11, 2026

Retrothermodynamics

The psychological experience of feeling energy and motivation flow backward. In normal thermodynamics, heat flows from hot to cold. In retrothermodynamics, your weekend motivation mysteriously drains into the void of your upcoming Monday. It’s the law that dictates how your excitement for a project evaporates the moment you sit down to work, only to reappear when you're trying to fall asleep. It’s the science of why the battery in your brain is always at 1% when you need it most.

Example: "I had all this energy to go to the gym after work, but by the time 5 PM hit, retrothermodynamics had pulled all that heat into my couch."

by Dumu The Void March 11, 2026

Retroentropy (Physics)

A hypothetical physical phenomenon where entropy—the measure of disorder—would decrease over time within a closed system, effectively running backwards. In our universe, entropy always increases (the Second Law of Thermodynamics). Retroentropy would describe a cosmos where spilled milk leaps back into the glass, smoke reassembles into a cigarette, and scrambled eggs unscramble themselves. It's the physics of a world where time flows in reverse, order emerges spontaneously from chaos, and the universe gets younger and more organized with every passing moment.

Retroentropy (Physics) Example: "Watching the DVR replay of the vase shattering and then magically reassembling, I joked that my living room must be a local zone of retroentropy."

by Dumu The Void March 11, 2026

Retrothermodynamics (Physics)

The hypothetical physics of heat, energy, and work operating in reverse temporal direction. In retrothermodynamics, heat would flow spontaneously from cold objects to hot ones, friction would accelerate objects instead of slowing them down, and engines would run by absorbing exhaust fumes and fuel while outputting work and air. It's what you'd get if you took a video of normal thermodynamic processes and played it backward—a universe where every energy transaction is perfectly reversed, and the arrow of thermal time points the other way.

Retrothermodynamics (Physics) Example: "The movie scene where a character's breath unfreezes and returns to their mouth is a charming moment of cinematic retrothermodynamics."

by Dumu The Void March 11, 2026

Retromechanics (Physics)

A speculative branch of physics concerned with mechanical systems operating under time-reversed conditions. If you could reverse time, Newton's laws would still hold (they're time-symmetric), but every collision, every trajectory, every mechanical interaction would play out backward. Retromechanics describes this reversed world: balls un-bouncing, pendums unsweeping, planets un-orbiting. It's a useful thought experiment for understanding why the Second Law of Thermodynamics (which isn't time-symmetric) gives time its direction, even though the underlying mechanics don't care which way the clock runs.

Retromechanics (Physics) Example: "The simulation showed planets orbiting backward, demonstrating retromechanics—gravity doesn't care about time's direction, even though everything else does."

by Dumu The Void March 11, 2026

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."

by Dumu The Void March 11, 2026