This is one of those still-unverified theory that tries to reconcile quantum mechanics with General Relativity. I'm not in this field, so I have no expertise in it. But I know that for many people who have read about it, they are aware of String theory and it's competition, Loop Quantum Gravity.
In this video, Fermilab's Don Lincoln tries to explain LQG to the masses.
Keep in mind that this idea is still lacking in experimental support. The gamma ray burst observation that he mentioned in the video has been highlighted here quite a while back.
Without experimental verification, both String theory and LQG continue to have issues with their credibility as a science.