Sorry, I posted before you posted the above.

Yep, there are many theories, or more precislely hypothesies, floating around regarding the ultimate nature of gravity.

All of them explain more than our current theory. And we know that our current theory doesn't explain everything. But none of the better explanations have yet been tested or can yet be tested. Until they áre tested or can be tested, and via their testing can be shown to explain more than our current theory, we have to stick with our current theory.

Why would you feel this was a problem?