Why does gravity work?

Why would the V2 particles hit the object from one side? Wouldn't they hit it equally from all directions? Why do these particles hitting the bubbles cause it to move at all? If you're thinking of Newtonian mechanics, they are a direct result of the electromagnetic interaction, but what about uncharged particles such as neutrinos?Gravity affects them as well. Even if these problems didn't exist, how could this hypothesis explain the bending of space time? I don't particularly like string theory, and I hate the people that say that there are infinite universes, but I think it's the best contender that we have for quantum gravity.