Einstein's general theory of relativity rendered Newtonian gravity obsolete
However, the rest of Newton's work is NOT obsolete and even with gravity his equations still work OK, it is the explanation for gravity that has changed.
Classical (or Newtonian) and Quantum.
Newtonian, or classical physics applies to physical, every day things, while quantum physics is a type of theoretical physics that does not apply to any physical things.
Newtonian physics, also called classical or pre-relativistic physics refer to the physics after Aristotelian physics and before the 1920s when the theory of relativity was formed. They distinctly differ from Aristotelian physics in that they cover the physics of motion, scientific method, describe contact and non-contact forces such as magnetism
The two major divisions of physics are classical physics and modern physics. Classical physics deals with the study of macroscopic phenomena using principles such as Newtonian mechanics and thermodynamics. Modern physics, on the other hand, explores the behavior of matter and energy at the atomic and subatomic levels, incorporating theories like quantum mechanics and relativity.
If you consider the fact that the main three laws of classical physics are still called "Newton's" laws or that classical dynamic physics is called Newtonian, you could say he is still quite revered.
Newtonian physics fails to explain motion correctly in extreme conditions such as at speeds approaching the speed of light or in the presence of very strong gravitational fields where the effects of relativity become significant. Additionally, at the quantum level, where particles behave in ways that cannot be predicted using classical physics, Newtonian physics also breaks down.
Classical physics refers to the physics developed before the advent of quantum mechanics and relativity, focusing on the behavior of macroscopic objects in everyday conditions. It includes Newtonian mechanics, thermodynamics, and electromagnetism, providing a framework for understanding motion, energy, and forces at a larger scale.
Classical physics are the theories of physics came before the modern times and which are not widely excepted. Examples of such physics are Maxwell's theory of electromagnetism, Newtonian mechanics, and thermodynamics.
Newtonian Mechanics
Classical physics is the physics without considering quantum mechanics. This is the type of physics practiced by for example Newton (you might also come across the term Newtonian physics). General relativity is also a classical theory. The distinction is often used because quantum mechanics changed quite a bit in many fields of physics, so the term 'classical physics' allows for a clear distinction. The opposite of classical physics would be quantum physics.
In classical Newtonian physics - no. In classical Quantum Mechanics - no. However in the still uncertain realm of the accelerating universe and dark energy there is speculation that the conservation of energy (the most sacred of rules) may not be constant.
Newtonian physics and relativity differ in their treatment of motion and gravity. Newtonian physics describes motion and gravity based on absolute space and time, while relativity considers them as relative and interconnected. Additionally, relativity accounts for the effects of high speeds and strong gravitational fields, which are not addressed in Newtonian physics.