If there are other universes, would our universe feel their gravity?
We can’t be certain. Recent astronomical evidence supports the view that the universe is infinite in extent.
At the same time, Einstein’s general theory of relativity suggests that our universe is finite but lacking a boundary or outer edge. As an analogy, imagine that our universe is the surface of a sphere; this would give it a limited size without a boundary.
This ushers in the possibility that parallel universes exist “beyond” our own. If this were the case, we might expect to see peculiar motion of galaxies in our universe as they are pulled towards a massive neighbouring universe.
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