There was a time there, before the yellow sun theory took hold (which I think was in 1960), where all of Superman's powers was explained according to a gravity theory. When I say explained, I mean they just said it's gravity and didn't go beyond that to get into the mathematics.

Perhaps they should have stuck with that theory, as we really don't know a lot about gravity and how it fits into quantum mechanics.

From Wikipedia:

**Quantum gravity** (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of **quantum mechanics**, and where quantum effects cannot be ignored, such as near compact astrophysical objects where the effects of gravity are strong.

The current understanding of gravity is based on Albert Einstein's general theory of relativity, which is formulated within the framework of classical physics. On the other hand, the other three fundamental forces of physics are described within the framework of quantum mechanics and **quantum field theory**, radically different formalisms for describing physical phenomena. It is sometimes argued that a quantum mechanical description of gravity is necessary on the grounds that one cannot consistently couple a classical system to a quantum one. . .

While a quantum theory of gravity may be needed in order to reconcile general relativity with the principles of quantum mechanics, difficulties arise when one attempts to apply the usual prescriptions of quantum field theory to the force of gravity via **graviton bosons.** The problem is that the theory one gets in this way is not renormalizable and therefore cannot be used to make meaningful physical predictions. As a result, theorists have taken up more radical approaches to the problem of quantum gravity, the most popular approaches being **string theory** and **loop quantum gravity**. Although some quantum gravity theories, such as string theory, try to unify gravity with the other fundamental forces, others, such as loop quantum gravity, make no such attempt; instead, they make an effort to quantize the gravitational field while it is kept separate from the other forces.

Strictly speaking, the aim of quantum gravity is only to describe the quantum behavior of the gravitational field and should not be confused with the objective of unifying all fundamental interactions into a single mathematical framework. A theory of quantum gravity that is also a grand unification of all known interactions is sometimes referred to as **The Theory of Everything** (TOE). While any substantial improvement into the present understanding of gravity would aid further work towards unification, the study of quantum gravity is a field in its own right with various branches having different approaches to unification.