On 6/6/2015 10:24 AM, John Clark wrote:
On Fri, Jun 5, 2015 , LizR <[email protected] <mailto:[email protected]>> wrote:> (very much in theory) a TOE would describe everything - it would in principle be like "Laplace's demon" (though possibly only for a multiverse).Laplace's demon could make predictions and that is far more difficult than just making a description. Even if the world worked according to Newtonian physics you couldn't predict how 3 bodies of similar mass will interact over the long term, you could do it for 2 bodies and there are a few very specific orbits you can do it for 3 bodies but in general if there are 3 you can only make approximations, there is no exact solution that is general, so the longer the prediction of where the 3 bodies will be the more inaccurate it will be.
In a Newtonian world physics is deterministic, so there is an exact solution: the integration of the differential equations of motion. But in general there's no closed form solution in terms of simple functions. The differential equations are sensitive to initial conditions but even so numerical predictions can be good for a long time, as evidenced by predictions of planetary positions. There's a nice simulation of the chaotic motion of Nix, one of the moons of Pluto at
http://arstechnica.com/science/2015/06/chaotic-orbital-interactions-keep-flipping-plutos-moons/ Note the speedup. Brent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
