I recently heard it suggested that the weakness of gravity, compared to the other fundamental forces, might be explained if it “leaked” into other universes  that are adjacent to ours in a higher dimension.  If this were so, might the gravity from those universes not also leak into ours?

As I understand it, we infer the presence of “Dark Matter” from its gravitational influence, and suppose it to comprise the majority of matter in our universe, despite our inability to observe it directly. Might its invisibility be because it is not in our universe?

This explanation seems also to offer possible causes for other discrepancies between our expectations and our observations of gravitational effects such as that associated with Pioneer.