Final answer:
Classical physics views energy as continuous, while quantum physics considers it quantized. Conservation principles from classical physics are maintained in quantum mechanics via effects like Compton and photoelectric. The correspondence principle ensures that quantum mechanics align with classical physics for macroscopic phenomena.
Step-by-step explanation:
In classical physics, energy is seen as a continuous variable, meaning it can take on any value within a certain range. However, quantum physics reveals that in certain systems, energy is quantized. This indicates that systems can only possess certain discrete energy levels, rather than a smooth continuum of energy values. The concept of quantization was one of the crucial early indicators for the need for quantum mechanics to replace certain aspects of classical physics. In quantum physics, phenomena such as the Compton and photoelectric effects demonstrate how conservation of energy and momentum are maintained, reconciling quantum mechanics with these fundamental principles of classical physics.
Max Planck's contribution was pivotal, as he recognized that energy is quantized, aligning more with modern physics as opposed to classical physics. It was after Planck's hypothesis that classical physics calculations for energy began to fall short at the subatomic level, where quantum physics provided a more accurate description. Moreover, the concept of energy in relativistic physics incorporates the idea that mass can be converted into energy, which maintains conservation of energy across all inertial frames. These reconciliations show how quantum theory complements and extends classical principles where necessary.
Finally, the correspondence principle asserts that classical physics is a special case within the broader quantum physics framework, which matches quantum predictions with classical ones for large, slow-moving objects. This principle helps to bridge the gap between classical and quantum physics, demonstrating the conditions under which they converge.