Sci-fi physics: without the first law

Problem

What would it mean if energy were not conserved during thermodynamic processes? Discuss in five lines with a concrete example of “what would be possible”.

Solution

What would collapse. The first law states $\Delta U = Q - L$: internal energy changes only through heat exchanged or work done. If it collapsed, work “from nothing” could exist.

Consequence. Perpetual motion machines of the first kind would be possible: devices that produce work without consuming fuel or any form of energy.

Concrete example. An engine that runs forever and also powers an entire city, without ever burning fuel or recharging. Power stations and batteries would become useless.

Experimental reality. No experiment has ever shown $L > Q$ at constant internal energy: every supposed perpetual motion machine has turned out to be flawed or fraudulent (Simonyi 2012). Conservation of energy is among the best-verified laws of physics.

$\ev{\text{perpetual motion machines of the first kind}\to\text{work from nothing, never observed}}$

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Topics: Thermodynamics Concepts: First law of thermodynamics Skills: Analysis of limiting cases and science-fiction physics