Classical physics

Classical physics refers to physics theories that are non-quantum or both non-quantum and non-relativistic, depending on the context. In historical discussions, classical physics refers to pre-1900 physics, while modern physics refers to post-1900 physics, which incorporates elements of quantum mechanics and the theory of relativity.^[1] However, relativity is based on classical field theory rather than quantum field theory, and is often categorized as a part of "classical physics".^{[citation needed]}