A while back (several years ago), I recall reading that when two particles are placed in very close proximity to each other, gravity begins to act as a repulsive force. I began looking for that source recently, but can find no reference to it (except one source of dubious credulity). Could someone inform me whether I am recalling correctly? Or perhaps incorrectly, as I suspect? As a side note, I do know that the state of quantum gravity is still incomplete/unknown, so any pointers to hypotheses/theories (defunct or still in debate) where what I recall is actually correct would be great.