I've heard ideas thrown around explaining both the relative weakness of gravity (compared to other forces) and parallel universes. Gravity would be strong, but

I've heard ideas thrown around explaining both the relative weakness of gravity (compared to other forces) and parallel universes. Gravity would be strong, but prone to "leaking" along a hidden dimension, and the gravitational sum of those invisible worlds would explain the blobby, non-interacting nature of dark matter. I don't know of any scientists actually giving this consideration, but it does make for a fun head-canon.