Participate in expert physics discussion. Discussion on the nature and properties of matter and energy. This area is for topics that don't fit the other categories. Mainstream physics only.
Physics is the study of matter in motion. Physics is a science, its object of study is the observable universe.
The concept of motion has had to be revised in two different ways. There was the relativistic revolution that forced us to put an upper bound on speeds. Then there was the quantum revolution that forced us to abandon the concept of forces in dynamics and kinematics nearly altogether.
The concept of matter has had to be revised from a solid continuum to an field of atoms which are mostly empty space. As smaller and smaller substructures are discovered, we revise the concept further, even to include such things that would not be considered "matter" in years prior.