Particles accelerate without a push: this phenomenon is a perfect example of an endogenous process. I have laid the theoretical foundation for such a process in various earlier posts as will be explained below.
First question: what is the essence of why particles apparently spontaneously accelerate without a push?
Answer: endo-inertia (see post 23). This property does not mean that a particle is accelerating without a cause, “force/energy”, but that the cause, “force/energy” is for free.
Second question: what is the free driving “force” that makes particles accelerate ?
Answer: time (see post 15).
The underlying basic reason is the difference between endogenous and exogenous processes. This difference implies that the acceleration of a body by gravitation is not equivalent to the acceleration of a body by pseudo-gravitation or the push of a rocket or an elevator. Gravitation, acceleration and inertia are only equivalent to each other if they share the same driver. They are endogenously equivalent if this driving “force” is time (see also posts 3, 6, 12, 13, 19, 21, 24, 25 and 26).
I think it is time the Physics Community starts taking account of the difference between endogenous and exogenous processes and its corresponding consequences.