Between a proton and an electron, there exists force. If there was nothing between the two particles, then there would also be no force. Some postulate an exchange of virtual particles being responsible for the force. However, this is not necessary if it is understood that space exists between the particles.
What causes opposite particles to be attracted and yet not to combine while in close proximity? Why do electrons, "orbit" an atom (forming probability density functions or standing waves), without radiating away their energy and falling into ( combining with ) the nucleus? Why is time slower at the bottom of a gravity well?
Every space is bounded by a space which has one dimension less. A point has zero dimensions. A line has one dimension and is bounded by zero dimension points (the ends). A 2D surface (a circle) is bounded by a 1D line (the edge of the circle). A 3D volume (a sphere) is bounded by a 2D surface. 4D space-time is bounded by 3D space.
Travelling in one direction along a boundary eventually leads to the same starting point. This applies to the edge of a circle, the surface of a sphere, or travelling in one direction in space. Travelling in one direction in 3D space will eventually return you to the place where you started, because 3D space is the boundary of 4D space-time. This is usually interpreted to mean that there is no "outside" to the universe, and, consequently, no other universes (the existence/non-existence of other universes being inconsequential).
It has been postulated that as many as ten dimensions ( relativity ) and as few as six dimensions ( string theory ) are necessary to encompass the universe. The dimensions beyond 4 are orthogonal to 4D space-time. Force is isolated between orthogonal dimensions, i.e., a force along x is independent from orthogonal forces along y, z, etc...
Using current theory, it would seem likely that at the beginning of the universe there would have been tremendous distortions of space-time. In these distortions, there would have existed compressions, rarefactions and twists in space-time. Some of these distortions inevitably were also distorted along dimensions besides 4D. Since orthogonal dimensions are isolated, a distortion along another dimension is isolated from interaction with 4D space-time and is apparent as zero time, unchanging. Thus, during the start of the universe, distortions of space-time would have been locked in zero-time.
Photons do not age ( travelling at c, zero-time ), but neither do protons or electrons. One can consider protons and electrons as distortions along different orthogonal dimensions. The particles continue to exist in what is apparently a zero-time state. These distortions can travel through space, much like photons, although the distortions due to matter are much more significant.
Assuming that all particles created in the big bang are compressions of space-time, near the particles, space-time is stretched and they are attracted in order to lower potential energy. However, being in zero time, or orthogonal, once in proximity, the particles do not combine. Furthermore, electrons may "orbit" protons indefinately because they exist in a zero time state.
Particles are made of space-time. There is no discontinuity between particles and space-time. Consequently, there is also a decrease in the rate of time as one moves closer to particles. This extends out into space-time, and when large numbers of particles are present together ( mass ) gravity is present. As one moves down a gravity well, closer to particles, time slows, eventually to zero time at the particles.
Only at very high energy levels will enough force be exerted on particles to cause the space distortions to be released. In that situation, space "snaps back" and tremendous force is released against other nearby particles. Anti-particles recombine naturally since they are orthogonal along the same dimensions.
Space exists. Space is the boundary of space-time. Distortion of space-time is force. Energy is force times distance, which is also mass because the trapped distortions of space-time present since the big bang are matter.