“A Cosmic Crisis,” by Richard Panek, discusses possible reasons why the two methods used to measure the universe’s rate of expansion find conflicting values—a discrepancy known as the Hubble tension. I am puzzled that the article does not mention forces from outside our universe acting on it. Can’t we expect that there are other universes with mass like ours that will have gravitational, and possibly other, effects on us? I don’t mean quantum parallel stuff but other big bang results beyond our own. We live in a galaxy that is part of a cluster of galaxies in a universe. Why not a cluster of universes? How do we know we are not in collision with one that is pulling our universe in ways that massively mess with our measurements?