The Order of Time - Carlo Rovelli

An exploration of time from a physics point of view. I read it as I'm getting older and wondered what the hell time is anyway. I'm not sure I found out.

Key ideas

  • Time is relative. It runs at different speeds at different places. Up a mountain, it is slower. In space, it is slower still. It is also affected by speed. The faster something moves the less time passes.
    • Mass slows time around it.
    • Sun and earth fall around each other due to time.
    • Gravity is time
    • Speed slows down time.
  • The only law of physics that is directional is heat.
    • Always goes hot to cold, never the other way round.
    • Seeking equilibrium. Entropy.
    • Heat is the only distinction between past and future.
  • entropy is order to disorder. But we are just relying on our perceptions. Order is relative.
    • No distinction between cause and effect.
    • No shared present, multiple overlapping present times.
    • can overlap and circle back
  • Time is a field, acted on by other forces. Can stretch and change. Time is granular, made up of Planck seconds- smallest divisible unit.
  • Time exists in a superposition. Unsure of how it exists until it interacts with the world.
  • Therefore the past, present and the future are indeterminate

This page modified on 1 Jul 2021 at 19:30

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