Quantum vs Classical Mechanics
Quantum mechanics and classical mechanics are two cornerstones of physics we know today. Classical mechanics describes the behavior of macroscopic bodies, which have relatively small velocities compared to the speed of light. Quantum mechanics describes the behavior of microscopic bodies such as subatomic particles, atoms, and other small bodies. These two are the most important fields in physics. It is vital to have a proper understanding in these fields in order to excel in any part of physics. In this article, we are going to discuss what quantum mechanics and classical mechanics are, where they are applied, their special characteristics, the similarities between quantum mechanics and classical mechanics, their variations, and finally the difference between quantum mechanics and classical mechanics.
What is Classical Mechanics?
Classical mechanics is the study of macroscopic bodies. The movements and statics of macroscopic bodies are discussed under classical mechanics. Classical mechanics has three different branches. They are, namely, Newtonian mechanics, Lagrangian mechanics, and Hamiltonian mechanics. These three branches are based on the mathematical methods and quantities used to study the motion. For an example, Newtonian mechanics uses vectors such as displacement, velocity, and acceleration to study the motion of the object, whereas Lagrangian mechanics uses energy equations and rate of energy change to study. The proper method is selected depending on the problem to be solved. Classical mechanics is applied in places such as planetary motion, projectiles, and most of the events in daily lives. In classical mechanics, energy is treated as a continuous quantity. A system can take any amount of energy in classical mechanics.
What is Quantum Mechanics?
Quantum mechanics is the study of microscopic bodies. The term “quantum” comes from the fact that energy of a microscopic system is quantized. The photon theory is one of the cornerstones of quantum mechanics. It states that the energy of light is in the form of wave packets. Heisenberg, Max Plank, Albert Einstein are some of the prominent scientists involved in developing the quantum mechanics. Quantum mechanics falls into two categories. The first one is quantum mechanics of nonrelativistic bodies. This field studies the quantum mechanics of particles with relatively small speeds compared to the speed of light. The other form is relativistic quantum mechanics, which studies particles moving with speeds compatible with the speed of light. Heisenberg’s uncertainty Principal is also a very important theory behind quantum mechanics. It states that the linear momentum of a particle and the position of that particle in the same direction cannot be measured simultaneously with 100% accuracy.
What is the difference between Classical Mechanics and Quantum Mechanics? • Quantum mechanics is applied to microscopic bodies whereas classical mechanics is only applicable to macroscopic bodies. • Quantum mechanics can be applied to macroscopic bodies but classical mechanics cannot be applied to microscopic systems. • Classical mechanics can be considered as a special case of quantum mechanics. • Classical mechanics is a fully developed field whereas quantum mechanics is still a developing field. • In classical mechanics, most of the quantum effects such as energy quantization, uncertainty principal are not useful.

u7885 says
Quantum mechanics deals with probabilistic rules in the unfolding of the universe, where as Classical mechanics deals with a universe of what appears to be certainties.