Classical physics is the study of the physical laws that govern the motion of macroscopic objects, while modern physics focuses on the behavior of subatomic particles and the laws of quantum mechanics.
The theory of relativity is a fundamental theory in modern physics proposed by Albert Einstein, which explains the relationship between space and time and the effects of gravity on objects.
Quantum mechanics is a branch of modern physics that studies the behavior of particles at the atomic and subatomic level. It explains the principles of wave-particle duality and probabilistic behavior of particles.
The Standard Model is a theory in modern physics that describes the fundamental particles and the forces that govern them. It explains the interactions between particles and has been highly successful in predicting and explaining experimental results.
Some of the unanswered questions in modern physics include the unification of gravity with the other fundamental forces, the nature of dark matter and dark energy, and the existence of a theory of everything that can explain all physical phenomena.