4 ms·
the short answer as to why this doesn't matter is that objects fast away from each other don't move quickly enough relative to each other for it to matter. sinc
by adgjlsfhk1 4y ago
the short answer as to why this doesn't matter is that objects fast away from each other don't move quickly enough relative to each other for it to matter. since gravity falls off with distance squared, changes in gravity go with 1/r^3, so at large distances the difference in gravitational pull will be very small.
- dreamcompiler 4y agoAnd the contribution to the field from the center of mass of the overall system will be huge -- even predominant in many cases -- but it never moves.
- uoaei 4y agoThe Lyapunov exponent of such a system is positive -- and probably substantially so, since there are thousands to millions of massive objects being simulated -- so it seems at first pass as if the absence of any determining factor in the dynamical model will hugely affect the simulation's evolution.
- sebzim4500 4y agoSure, but the goal of these simulations is qualitive results about how galaxies behave, not a quantitative prediction of exactly where every star will be in a billion years. It's like predicting climate vs. weather.
- uoaei 4y agoAny smoothed and incomplete approximation to climate models is also devestating for qualitative similarities of results to data. The point is that the chaos inherent in the dynamics means that n-body solvers that aggregate e.g. spatial regions into low-rank approximations are losing enough detail that it could result in different dynamics being expressed. Like using too large of a mesh size in CFD calculations.