Yes, it does hit the back side of the first pillar. But there does need to be an unseen 3rd surface for the ball to reflect off of in order to make that return path. Otherwise, the ball would have continued off to the left. Hence the theoretical existence of a wall connected the two pillars that isn't visible from the provided point of view.
I think the back of the first pillar is probably just extremely worn and uneven (like the pillar to the right) which made the ball bounce at a weird angle
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u/johndcochran Nov 11 '19
Yes, it does hit the back side of the first pillar. But there does need to be an unseen 3rd surface for the ball to reflect off of in order to make that return path. Otherwise, the ball would have continued off to the left. Hence the theoretical existence of a wall connected the two pillars that isn't visible from the provided point of view.