How do you understand this idiotic physics?

One of the important concepts of modern physics which Aristotle didn't use is experimentation. While modern physics relies on experiments, Aristotle mostly philosophised.

Understand is the verb, never understand is the verb phrase.

The verb phrase is "will understand" (the 'll is the contraction form).

Wikipedia gives you a good definition and a very large list of areas. There's also the "Simple English" wikipedia. They give a very short and good definition for Physics. See...

The main branches of classical physics include: Classical Mechanics Electromagnetism Optics Thermodynamics As well as many other sub-branches like hydrodynamics, aerodynamics, etc. In modern physics,...