In one night-time experiment he drove a truck 10km from where he and companions were camping, parked at the bottom of a water-course, pointed the truck toward the camp, and switched the lights on and off while maintaining radio contact. His companions in the camp saw the min-min come and go in synchrony with the truck lights going on and off.

The min-min is a mirage that occurs when a layer of warm air lies above a layer of colder air near ground level. The cold layer traps lights by refraction and may channel it over long distances. During day-time people easily estimate distance using their binocular vision and reference points like mountains, trees, etc. At night such estimation is difficult and therefore, if a light is seen, people rely more on brightness cues. A light that's getting brighter may then be interpreted as getting closer or even as chasing the observer.