Conservation of Energy
Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed on it.
the speed of light within a vacuum is the same no matter the speed at which an observer travels.
Special Relativity
the variable in an equation which represents a conserved quantity is constant over time.
Newton's Laws
It has the same value both before and after an event.
the laws of physics are the same for all non-accelerating observers
For every action there is an equal or positive re-action
