First, before anything, I am not anyone special, so some of what I say, might be wrong. In QFT, interactions result from exchange of virtual particles. These virtual particles are known as force carriers. For the electromagnetic force, they are photons. For the strong force, they are gluons. For the weak force, they are the W and Z bosons. All those forces are expressed as gauge theories. A gauge theory essentially says that all interactions are manifestations of symmetries. Gravity is also a force and is able to interact, therefore it also needs a force carrier, so the hypothetical graviton was hypothesized. Astronauts come back to earth younger than they would have been had they stayed on earth for that same period of time. They are traveling so fast relative to the earth that time slows down for them. Does that mean that time is also a force? Time interacts with speed...and all interactions are manifestations of symmetries. So should there be another hypothetical force carrier for time....the timetron? ready, set, tell me why ime wrong.