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
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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.
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Mass slows time around it.
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Sun and earth fall around each other due to time.
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Gravity is time
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Speed slows down time.
The only law of physics that is directional is heat.
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Always goes hot to cold, never the other way round.
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Seeking equilibrium. Entropy.
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Heat is the only distinction between past and future.
Entropy is relative
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No distinction between cause and effect.
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No shared present, multiple overlapping present times.
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can overlap and circle back
Time is a field, acted on by other forces.
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Can stretch and change.
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Time is granular, made up of Planck seconds- smallest divisible unit.
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Time exists in a superposition. Unsure of how it exists until it interacts with the world.
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Therefore the past, present and the future are indeterminate