News for hackers. Stuff that matters.

A comment on A meteorite hit the moon during yesterday's total lunar eclipse. Parent comment

Re:A meteorite hit the moon during yesterday's total lunar e... by pdonis on Tuesday January 22, 2019 @11:07PM (#18975599)
> The path of a meteor is only going to be deterministic on a timescale given roughly by the largest Lyapunov exponent associated with its orbit.

No, it's only going to be predictable on that timescale. The uncertainty involved has nothing to do with quantum uncertainty; it's purely classical uncertainty because we can only make observations with finite accuracy.

[ Parent | on HN ]
Re:A meteorite hit the moon during yesterday's total lunar e... by tlb on Tuesday January 22, 2019 @11:30PM (#18975688)
The Lyapunov time scale defines the time for any variation of position or momentum to be amplified by a factor of e. The exponential growth applies equally to a measurement error and a quantum event affecting the object's momentum. Quantum events such as alpha decay (shooting out a helium nucleus with momentum of about 1e-21 Ns) start off small but after 50 Lyapunov times can get huge.
[ Parent | on HN ]