About your question regarding discontinuity in space at the Plank scale (10^-33), gravity as a result of mass-energy's curvature in 3-D space time and their relation to"gravitons", and reverse time causality....

A mathematical space is continuous if it has a metric that withstands infinitesimal subdivision. Simply put, a metric is just a general "distance" relationship defined on a space as follows: if a and b are two points in a space, and c is a third point, then the distance between a and b is always less than or equal to the sum of the distances between a and c, and b and c. That is, where d(x,y) is the distance between two points x and y,

d(a,b) <= d(a,c) + d(b,c).

If this relationship continues to hold no matter how close together the points a, b and c might be, then the space is continuous. On the other hand, where the distance concept is undefined below a certain threshold, metric continuity breaks down on that scale. Since the Planck limit is such a threshold, space is discontinuous below the Planck scale...implying, that it is discontinuous. Not only is it "granular" in a slippery kind of way, but the grains in question are without spatial extent.

Because space and time are undefined below quantum limits, they no longer have extensionality or directionality. But if we interpret this to mean that anything, including causality, can "flow" in any direction whatsoever, then reverse causality is conceivable on sub-Planck scales..... In fact, some theorists argue that on these scales, continuous spacetime becomes a chaotic "quantum foam" in which distant parts of the universe are randomly connected by .....microscopic "wormholes".....

Now let's bring philosophy in the bowl of cereal. At one time, space was considered to consist of "ether", a quasimaterial "substance" which physical objects were thought to swim through like fishies in water. But since the introduction of Einstein's Theory of Relativity, nothing material remains of empty space; although it is permeated by fields and "vacuum energy", these are merely contained by space and are not equivalent to space itself. Space has instead become a mathematical abstraction called a "tensor field" that confers relative attributes like location, direction, orientation, distance, etc. on physical objects and energy fields. Because empty space, as abstracted from its contents, cannot be observed and has no observable effect on anything, it is not "physical" in the usual sense. That which is immaterial is abstract, and abstraction is a mental process that "abstracts" or educes relationships from observations. ......So from a philosophical view, saying that space is immaterial and therefore abstract amounts to saying that it is "mental"...that it is to some extent composed of mind rather than matter. Although this runs against the scientific grain, it is consistent with our dominant physical theories of the very large and the very small, namely relativity and quantum mechanics. In relativity, space and time are combined in an abstract manifold called "spacetime" whose "points" are physical events that can be resolved in terms of mutual behavioral transduction of material objects, a process fundamentally similar to mentation. And quantum mechanics describes matter in terms of abstract, immaterial wave functions that are physically actualized by interactions of an equally immaterial nature...so, what the Hell does this mean regarding spacetime? Simply that like spacetime itself, continuity and its quantum-scale breakdown are mental rather than material in character. As Berkeley (the bald mathematician/philo) observed centuries ago, reality is ultimately perceptual, and as we know from the following debate between Hume and Kant, perception conforms to mental categories... categories like space and time. So rather than being purely objective and "physical" in a materialistic sense, space has a subjective aspect reflecting the profoundly mental nature of our REality...

Gravitons, and sandwiches though subject to some of the same reasoning, are another matter...