That you can always work backwards is true only if the mathematics describing an interaction between particles is continuous and two different prior states can never produce the same following state.(adsbygoogle = window.adsbygoogle || []).push({});

Inelastic collisions are not described by such math. (But one could argue that there is no such thing as an inelastic collision...!)

Perfectly elastic collisions can be described by such math only if you disallow point particles.

Allowing point particles allows for infinite prior states to result in the same following state

(the angle of line of approach to the line of separation is unconstrained)

Doesn't quantum mechanics allow multiple prior states to map to the same following state?

(Any system that employs math that does not allow infinite precision will have the problem that multiple prior states could result in the same following state)

On the flip side - this is the same argument as determinism vs existence of free will.

Niket Patwardhan

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# B Black Holes and Information

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