Basics of Quantum Mechanics for Dummies

According to Niels Bohr, the father of the orthodox 'Copenhagen Interpretation' of quantum physics, "Anyone who is not shocked by quantum theory has not understood it". As seen by a layman, quantum mechanics appears to be more like a bizarre phenomenon or science fantasy flick, full of jargons and complicated mathematical equations. However, it is easier to take a look at the basics of quantum mechanics for dummies, provided one isn't baffled by the fact that every electron is a particle, as well as a wave at the same time.

Introduction to Quantum Mechanics

Quantum mechanics is the branch of physics which deals with the study of particles to the extent of atomic and sub-atomic level. The term 'Quantum Mechanics' was given by Max Born in 1924. With the discovery of electron, by J.J. Thomson, in the year 1932, the whole idea of classical physics was shown to be inapplicable at the atomic level. Classical physics which was governed by the Newton's laws of motion and Maxwell's laws of electromagnetism, was used to define and predict the motion of particles. But this theory was not able to explain the following three critical and world famous experiments:

1. Black Body Radiations: According to the classical theory, a black body would emit infinite amount of energy, which was not true. Max Plank developed an equation and came up with Plank's constant (h) for energy radiated in black body emission.
2. The Photoelectric Effect: The phenomena of photoelectric effect occurs when electrons are released from certain metals, by the action of light. The electromagnetic theory of light predicts different results than what is recorded experimentally. Using the Plank's constant 'h', Einstein worked out a formula for the energy of electrons emitted in the photoelectric effect in the year 1905.
3. Optical Line Spectra: Neils Bohr conducted an experiment to study the optical line spectra and gave the famous Bohr's model of atom.

All the formulations by these three scientists laid ground for the Old Quantum Theory. It was further amended by scientists like W. Heisenberg and E. Schrodinger to form the New Quantum Theory.

Basics of Quantum Mechanics

Following are some of the basic points for understanding quantum mechanics:

• Schrodinger's 'cat in the box' experiment: This is a hypothetical experiment in which we put a cat inside a box with some equipment which releases poisonous gas on detection of electrons. In this case, after an hour, one would say that he doesn't know whether the cat is dead or alive, and this can be known only by looking inside the box. But according to quantum theory, it is better to say the cat is half dead or half alive, until we check on it. Confused! Actually it is based on the basic assumption of probability and not the fact. Fact comes in picture when we actually see inside the box, till then it's all about probability.
• Energy is quantized i.e. it is in form of 'quanta' or small packets. Sounds illogical, but this is the very basic principle followed by scientists working in the field of quantum mechanics.
• Moving objects don't have a well defined position. We can just graphically represent the probability of the existence of that object with respect to time.
• Heisenberg's uncertainty principle: It states that, the more precisely the energy of an object is known, lesser is certainty in calculation of its position in time, and vice versa. This is also applicable for the position and momentum of an object.
• Quantum mechanics allows one to think of interactions between correlated objects, at a pace faster than the speed of light. It also lays down the foundation of the advanced Theory of Relativity.
• The empirical properties of light cannot be explained if it is considered to be a wave or particle. It can be explained only when light is considered to be both.

At the initial stage, one might find his brain circuits getting fused, while reading about the basics of quantum mechanics. But as he goes deeper into the intricacies and complexities of equations, and sees the application in real life, he is bound to be fascinated. The world is not just what is seen by naked eyes, but something which is far beyond our comprehension. Quantum mechanics has revolutionized the study of physics, and opened the gateway to see new horizons.