It still applies. The classic scenario involves birthdays, a one-dimensional space that closes in itself; while this one is a three-dimensional space that is c

It still applies. The classic scenario involves birthdays, a one-dimensional space that closes in itself; while this one is a three-dimensional space that is closed on two of them. Airborne objects also move so I don't know if that decreases or increases the probability of collisions, I guess it depends on how much correlation there is between their movements. It sounds like a fascinating thing to study!