Elias sighed, pointing to the glowing heat vents in the floor. "The Second Law of Thermodynamics. The 'Entropy Tax.' No matter how much energy you buy, you can’t use all of it. Some always leaks out as heat. You’re paying for 100% capacity, but you’ll only get about 40% of the actual work. The rest belongs to the universe now."
Elias was a "Watt-Tracer," a man who made his living brokering the one thing the universe promised to eventually run out of: the ability to do work. In physics, you don’t "buy" energy like a physical object; you buy the what you buy energy in physics
"Energy is the ultimate commodity," Elias muttered, watching the meters climb. "The universe is a giant ledger. When you 'buy' energy, you’re just paying to move it from one account to another. You take it from the chemical bonds in a fuel or the heat of a star, and you force it into a kinetic state—motion—to get your job done." "And the tax?" Lyra asked. Elias sighed, pointing to the glowing heat vents
He began the transaction. He wasn't handing her a box; he was routing a stream of electrons from the city’s fusion grid to her heavy-lift exoskeletons. Some always leaks out as heat
Elias tapped his terminal. "You're not buying 'stuff,' Lyra. You’re buying . To move that mass against gravity, you need to purchase Gravitational Potential Energy . That’s a product of mass, gravity, and height. It’s expensive."