Newton's third law cannot be proven in the traditional sense, as it is a postulate assumed to be true, similar to axioms in mathematics. Instead, it is derived from experimental observations and the principle of conservation of momentum. The law states that for every action, there is an equal and opposite reaction, which can be demonstrated through the behavior of forces in isolated systems. Newton likely built upon existing concepts, such as momentum conservation, rather than deriving the law solely from his own observations. Ultimately, physics laws are validated through their ability to generate accurate predictions based on experimental evidence.
