Speculative physics: without energy conservation. What would change in the world if energy were not conserved? Discuss, citing at least one machine or phenomenon that would be possible today.
Solution
If energy were not conserved, the first law of thermodynamics would fall, which states with the total energy constant in an isolated system.
What would become possible. Perpetual motion of the first kind: a machine that produces work out of nothing, without consuming any energy source. Examples that are impossible today:
- a wheel that spins forever and drives a generator with no fuel or battery;
- heating a room for free, creating heat without burning anything;
- a car that accelerates indefinitely with no fuel tank.
Consequences. Power plants, batteries, fuels and energy grids would be useless: energy could be generated at home from nothing. The whole economy and physics as we know it would collapse.
Why it doesn’t happen. The first law is not a theorem proved a priori: it is an empirical law. It arises from the experimental fact that, over centuries of attempts, no machine with has ever worked. Every time energy seemed to disappear, a hidden reservoir was discovered (heat, internal energy, mass-energy). Conservation is the generalisation of this systematic failure of perpetual motion.
Collegamenti
Argomenti: Work and energy Concetti: Conservation of mechanical energy Competenze: Analysis of limiting cases and speculative physics