they are in balance. A group of stones which do not touch one another are not a system, because there is no interaction. A system can be modeled. This means another system which supposedly replicates the behavior of the original system can be created. Theoretically, one can take a second group of stones which are the same weight, shape, and density as the first group, pile them in the same way as the first group, and predict that they will fall into a new configuration that is the
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