On Sun, Jun 23, 2013 at 3:50 PM, <[email protected]> wrote: ...so what is the boundary condition? I.e. when does it happen, and when > not? > How strong does the force have to be? >
I think it would be analogous to the pull of gravity by the sun on the earth, except in the opposite direction (a repelling force rather than an attractive force). Suppose the sun went supernova (for some unclear reason). My understanding is that earth would happily continue in its present orbit for 8 minutes and 20 seconds before taking into account that something bad has happened. So the boundary conditions would be something like this -- the geometry of the effect of the nucleus on the nuclear reaction underway would be the same as in the current calculations; i.e., a far-away nucleus would have a vanishingly trivial influence. Only the dimension of time would be relevant. If the nucleus was in the same location at some point prior to the reaction, and then for some reason disappeared, it would take the amount of time required for the travel of the speed of light before the effect would be felt by a series of fusion reactions. The earlier ones in the series would take the nucleus into account and the later ones would not. More likely, the nucleus would not disappear in a puff of smoke, and you would just get a "smearing" effect within the dimension of time of the influence of the nucleus that was for all practical intents indistinguishable from an instantaneous influence. Maybe I'm misunderstanding a subtlety of your question. Eric
