Correlation between successive velocity sign reversals within impact theory Original Research Article

The correlation between events of velocity sign reversal is studied within the framework of impact theory (IT). It is shown that under the assumption of uncorrelated time intervals between instanteneous collisions generally used in IT, the time intervals between velocity sign reversals are correlated. However, this correlation is rather weak, so that the recent uncorrelated successive velocity reversal model (USVRM) should be considered as a reasonable approximation for a hard sphere fluid. We confirm that in two particular cases of strong and anticorrelated instanteneous collisions USVRM becomes rigorous. At any other collision strength, the dependence on the previous history vanishes only at some “magic time” which is found analytically in the case of weakly correlated collisions.