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Chapter 10 of 10All chapters

Chapter 10 of 10

Time and the universe

The largest consequence.

The arrow of time

Most physical laws work equally well forwards and backwards. The second law does not, which is why we remember the past and not the future.

  • A smashed cup never reassembles, though no law of force forbids it.
  • The asymmetry traces back to the universe starting in a very low entropy state.

Heat death

Extrapolated far enough, the universe approaches uniform temperature with no gradients left to do work. It is a long way off, and it follows from the same law that limits your car engine.