I used a new perfect (but simple) Newtonian physics engine to reverse a billiards break. The simulation surprised me. I expected it to re-form a stationary triangle of balls and spit out the cue ball. It did not.
This means that classical physics is non-deterministic and not practically reversible.
The simulator is perfect in that it keeps times, positions, and velocities
as expressions--3*sqrt(7)/7--rather than using numeric approximations. Its worlds are 2D with circles, infinite walls, and elastic collisions.
In article <f228b69d-cd2b-47ba-b503-56ea2a37617an@googlegroups.com>,
Carl K <carlk@msn.com> writes:
I used a new perfect (but simple) Newtonian physics engine to reverse a
billiards break. The simulation surprised me. I expected it to re-form a
stationary triangle of balls and spit out the cue ball. It did not.
This means that classical physics is non-deterministic and not practically >> reversible.
It does not mean that it is non-deterministic. Make a movie of the
billiard break and run it backwards: perfectly valid physics. Classical physics is reversible.
That it is not reversible in practice is a different matter, but that
was known before the simulation.
On 11/30/2022 2:19 AM, Phillip Helbig (undress to reply) wrote:e a
In article <f228b69d-cd2b-47ba-b503-56ea2a37617an@googlegroups.com>,
Carl K <carlk@msn.com> writes:
I used a new perfect (but simple) Newtonian physics engine to revers=
rm abilliards break. The simulation surprised me. I expected it to re-fo=
icallystationary triangle of balls and spit out the cue ball. It did not.
This means that classical physics is non-deterministic and not pract=
calreversible.
It does not mean that it is non-deterministic. Make a movie of the billiard break and run it backwards: perfectly valid physics. Classi=
physics is reversible.
That it is not reversible in practice is a different matter, but that
was known before the simulation.
Is it chaotic in a way, that is, a tiny change in the backwards action
causes a completely different outcome?
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