Question

What exactly is Quantum mechanics?

Answer 1

Hint: Quantum mechanics is a theory of physics; it deals with atoms and subatomic particles. Hence, it studies phenomena at the microscopic level rather than the macroscopic level as most phenomena cannot be explained at the macroscopic level.

Complete answer:
Quantum mechanics is a theory in physics which explains the properties of matter at the atomic and subatomic levels. It forms the foundation for all of quantum physics like quantum chemistry, quantum information science, quantum technology etc.
It differs from classical physics because in it all values like energy, velocity, acceleration etc are restricted to discrete values or quantized values. All objects at the quantum level have both wave as well as particle nature and according to uncertainty principle, every value cannot be calculated with utmost accuracy. Basically quantum mechanics came into play to explain phenomena which cannot be explained using classical theory like black body radiation, photoelectric effect etc.
The very first structure of atoms was given by Dalton but later it was discarded and more and more scientists conducted experiments to develop on the structure of atoms and hence explain the phenomenon covered under quantum mechanics.
Therefore, quantum mechanics is the theory of physics which explains the working of nature’s laws at the atomic and subatomic levels.

Note:
Light as well as matter both possesses wave nature as well as particle nature as considered in quantum mechanics. Uncertainty principle gives a mathematical inequality according to which we cannot predict the momentum and position of a particle simultaneously.