Perspectival Ball Mixing

The box is filled with balls that bounce around the box at random.

The balls in one half of the box can be painted, with paint that is only visible when viewed with the corresponding filter.

Depending on when the balls are painted and which filter is used, the box can be moving from unmixed to highly mixed in both time directions.

This is based on the example (Fig. 1.) used by Carlo Rovelli from this paper, which contains lots of complicated mathematics I don't understand:

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