second law

The four laws of thermodynamics, what entropy really means, heat engines, black holes, the arrow of time, and why life is a local entropy reversal.

Carnot proved thermodynamic limits on engine efficiency. His theoretical work established the maximum possible efficiency any heat engine could achieve, a law of nature rather than a failure of engineering.

Entropy is the reason ice melts, eggs don't unscramble, and the universe is heading toward a quiet, cold end. Here's what entropy actually is — and why it's the most powerful idea in physics.