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Jim, struggling but not quite succeeding in giving up the idea of a center, writes:
"In fact they are distinguishable, as objects dropped in (1) will converge, however slightly – because there’s a convergence toward the center of mass(!)"

The principle of equivalence deals with one object's accelerated frame of reference. It applies to each object individually, but the convergence implies multiple objects and multiple frames of reference.

Jim, you might like a book that I reviewed less than favorably: The View from the Center of the Universe.

Time for me to sign off on this topic.

Fred Bortz -- Science and technology books for young readers (www.fredbortz.com) and Science book reviews (www.scienceshelf.com)