Early physics concerned itself with mechanical movement and what things did when they bumped into or were influenced by each other because physics only saw particles / objects and events. With the discovery of electricity and our development of radio and TV, physics started to explain things in terms of fields, since fields radiated information which we saw as words, ideas, and pictures. Einstein appeared and started to discuss physics in terms of enclosures or frames and how we saw things if we were the occupants of those frames or enclosures. He also discussed frames in relationship to each other when they had velocity, accelerated or when their velocity reached the speed of light. Physics started to be applied to everything and astronomers were the first to notice that the movement of the galaxies and their contents couldn’t be totally explained by matter we could eyeball. This matter was called dark and it still remains a mystery. Here’s a possible answer from string theory. In our everyday world, we experience gravity, space and time. Suppose for the sake of argument, gravity, space, and time were actually strings. In our world, we do not see gravity, space and time as strings because our sight doesn’t have that acuity. If strings were the basis of dark matter, gravity would be an energy string, space a matter string and time a force string. Our physical limitations as a particle / object allows us to experience gravity as something that keeps us in place which is a form of energy. We apply energy to things and convert it, which is really the horizontal application of gravity to allow us to move. We do not experience space as matter because we can’t see space except as something abstract. If we could eyeball space we would see it as a string of dark matter which flexes and curls. Einstein had a hint of strings when he talked of space curving, light following a curve, and plant orbits. Time is a string of dark force. Our closest sensation of time as a dark force is its’ ability to move everything outward in a forward direction.
In short physics had 4 phases:
The 3 primary ones are: