While all observations in physics carry weight in determining if a model is accurate, the crux of why this model is correct is because it explains the so-called fundamental force of electromagnetism to be the result of gravity.
The universe is infinite and eternal. By being infinite, it is also infinitely divisible. Particles sufficiently small relative to atoms are what we would recognize as "infinitesimal". When one such infinitesimal particle is proximal enough to a relatively "infinite" body, the force of gravity exerted on the object is sufficient to pull it back towards the center of mass of the infinite body regardless of angle of travel and velocity. In other words, even when traveling at essentially the speed of light directly away from the "infinite" object, the infinitesimal is pulled by the force of gravity back to the object's center of mass. However, because it is so small it travels through the infinite (as evidenced by neutrinos traveling through the Earth), so that gravity is then in the opposite direction and the process is repeated. This produces a Figure-8 orbital flow pattern for the infinitesimal. When there are "infinite" infinitesimal in such an orbit, the summation of the flow of all the particles is what we observe as electromagnetism, which is why electromagnetism depends on rotation to pull infinitesimal particles into curved flow patterns before the particles can escape gravity. Electromagnetism is not a fundamental force of nature, but rather the result of gravity due to the river of the infinitesimal flowing in Figure-8 orbitals through a given rotating body.
Because electromagnetism can be explained as the result of gravity through recognition of the infinitesimal being manipulated by the gravity of a given mass, this indicates that this is not just an approximation but rather the fundamental underlying way that the universe functions; it is what has come to be termed "the Theory of Everything." For the full theory and explanations of how this model arrives at many other key observations in the cosmos, see the complete details at The Universal Principle of Natural Philosophy.