Space-time behaves as a liquid. each particle that makes up the liquid is very small (really, unimaginably teeny-tiny). There is a definite amount of space between particles. This space is determined by the instantaneous strength of the gravity field at that location.
The particles can move. They're not in fixed positions. This allows them to flex with changing gravity field conditions. It also means that space itself is also mobile. Just like stirring a spoon in the center of a pot of water causes all the water to rotate, so does a spinning galaxy cause all the space throughout it to eventually spin with it. This helps explain why the outer edges of galactic arms spin faster than traditional gravity theories describe.
Gravity fields are infinitely fast, because they operate outside the structure of the matter-energy we see, and operate on the substrate of the universe itself. As do electromagnetic fields. This is easily explained in thought experiments.
- EM fields (not waves or particles acting in those fields) propagate faster than light, most likely infinitely fast. (It doesn't actually matter how fast they move, since they're moving faster than anything we could possibly use to measure them with.) Perform a classic two slit experiment. Notice how the photons form an interference pattern. Now slow the experiment down. Emit single photons in a stream - they still form an interference pattern. Slow the experiment down even further, so that a single photon is being emitted every few minutes. The photons still exhibit the interference pattern. (This experiment has actually been done.) Think about this. How does the photon know where to go, if the field wasn't ALREADY THERE, guiding it? The field MUST move faster than the photon, in order to form the interference patterns that guide the motion of the photons. If it's moving faster than the photon, it is by definition moving faster than the speed of light.
- The Earth moves towards where the sun actually is, not where it's light makes it appear to be. Gravity fields move faster than light. This effect can also be seen between stars, and even between galaxies. Gravity is istablished as being faster than light.
Photons move forward at the speed of light. They also rotate about the axis of movement at various speeds. This axial rotation is what is counted as the energy of a photon. What it is is the rotational velocity, measured more easily as frequency. There is a minimum frequency, 1, as established by Plank energy. There is a maximum frequency, determined by the speed of light. (The rotational velocity cannot exceed C.) This means that there is a maximum energy of a photon, which is bounded by C.
Time is distance. Distance is time. This is actually provable. C is a constant. Measurement units are arbitrary, so let us set the velocity denoted by C to 1. So C=1. But we know that velocity (what C actually is - a fixed velocity) is distance per unit time. C = D/T. In our units, C=1, so 1 = D/T. Multiply both sides by T, and you get T = D. Time is distance, distance is time. This is why objects traveling at near the speed of light shrink in their forward axis, in the same proportion as their subjective time slows down.
Remember that whole space-time particle thing? Yeah, the distance between each particle and the next is both distance and time. Quite literally.
SpaceTime gets more dense in higher gravity fields. (It acts as a liquid.) The particles are simply forced closer together. (No, I don't know why this works. I'm just working on 'how' and 'what' here.) That means that in areas of higher gravity, space is smaller, and time runs more slowly. As is proven in several experiments, where atomic clocks with vertical spacing as little as one meter from the Earth run at different speed.
The force acting upon matter and energy that we call gravity is actually just time. Each point of SpaceTime has a time vector pointing away from it. The strength of this vector is proportional to the local gravity field, and points in the direction of higher gravity. Or, more simply, the vector points at the closest other point of SpaceTime, with a strength proportional to the square of the inverse of the distance between the points. (Sound familiar?) There is an ideal distance between points, arbitrarily declared to be 1 unit, which is how far two points of SpaceTime would be from each other in the absence of any gravity field strength. Gravity is the directional flow of time. It acts on all matter and energy (E=MC^2, after all) equally at each point.
Velocity is also the directional flow of time. Remember T=D? Each piece of matter, each unit of energy (photons, etc.), has a velocity. That velocity is most easily explained as the direction that time flows for that object. This explains why time can never run backwards - the vector can only point away from the object or point. It can't point inwards, it could at most have zero length. (And even that is debatable. An object with no absolute velocity would experience no passage of time at all, and the universe would end before it ever did anything.) Velocity is directional time. Gravity is directional time. Objects moving in a gravity field alter their velocity based on the simple addition of time vectors. Inertia is time. The vector doesn't change, unless acted upon by some outside force. Such as another time vector, like gravity.
Remember how light has a rotational velocity? That is what is affected by adding or subtracting energy to the photon. This is also a time vector, just a rotational one.
E=MC^2. One minimal unit of mass is equal to the energy of one fully charged photon. Forward velocity C times rotational velocity C. Energy can obviously be less.
Time dilation due to speed is simply explained as perceived density of SpaceTime. The faster you go, the more dense SpaceTime appears to be, the closer the particles appear to be. So time appears to slow down, and length appears to shrink to others. Think of it as a ruler. At a speed of 1, the ruler has only one dot on it. No problem. At a speed of two, there are two dots. Scale this up, until the dots start crowding each other on the ruler. In order to put more dots on the ruler (increase speed), you have to make each of the dots a little closer to the others. This is where the time dilation effects start to be noticeable. Eventually, you can't add any more dots, because the ruler is full of them., and there simply isn't room for any more dots to be added. This is the speed of light - the maximum units of SpaceTime that something can travel, or the maximum strength of a time vector.
Notice that the speed of light is measured in points of SpaceTime. So light travels a smaller absolute distance in areas of higher actual (not perceived) density. Time slows down in areas of higher gravity.
'Reference frames' from General Relativity are areas with matching SpaceTime densities. If two objects are in areas of similar densities, they will have similar experiences of time and distance.
A Singularity is the place where the liquid of space time becomes a solid. Our rules of physics don't generally apply in the different medium. The points of SpaceTime are crowded together to the maximum possible density, and the time vectors of SpaceTime achieve the strength of C, raising the energy of each photon to maximum possible (turning it into matter?), but eliminating its ability to escape. The velocity vector is completely overwhelmed by the gravity vector, and becomes unimportant. Note that gravity and EM fields, acting outside of the strictures of the points of spacetime, still exist and propagate. (Think about it - if gravity and EM fields propagated at the speed of light, the gravity itself wouldn't be able to escape the gravity of a black hole, and it dwouldn't be able to generate a magnetic field. Obviously incorrect.) Interestingly, absolute time still passes, even though perceived time does not. (Photons still travel through space, even though they have no perceived time passage.) So the black hole moves, and rotates, and grows, while perceiving no passage of time. Indeed, as was stated by the scientist in the extras to the movie Interstellar, time flows towards the center of a black hole. (That's what gave me the flash of insight to come up with all the rest of this.)
Again, I'm sorry that this isn't more organized. I'm sure I missed something, and that this is probably harder to understand than it needs to be. The space inside my head isn't organized, either. I'm pretty bright - ACT 33, SAT 1460, Army GT score 145. My whole trick seems to be to grok things. I learn a new concept more slowly than others - but then there is the moment of clarity, where everything suddenly makes sense. And the concept becomes part of me, simple and beautiful. It's trying to explain these simple concepts that is difficult for me.
I've been doing more science reading, and I haven't found anything to refute the basic concepts presented here. That's not to say it's all right. I just haven't found anything to prove it wrong yet. And in physics, the simpler idea is usually the more correct one. Time = Distance. The force of Gravity and Velocity (inertia) are really Time vectors. SpaceTime is made of particles, that flow like a fluid. Higher gravity fields are places where the density of SpaceTime is higher (particles are closer together). Simple, really.
Edit 2020: So much of this is BS. Almost everything in the books I read on these subjects was wrong, or at least massively misleading.