Time-reverse

It is compatible with the time-reversal noninvariance of the laws that the universe be such that the universe that consists of just its states at a time in reverse temporal order, without even time-reversing the states themselves, is a possible physical universe.

The records of the waveforms are then transmitted to a central server that time-reverses them and lets the time-reversed versions back-propagate into the location domain by numerical simulation.

Time-reverse all motions and the three will return at the same instant to the starting point.