ARTICLE: Quantum Mechanics: Classical and Quantum Physics

One of the three fundamental theories of Physics includes quantum mechanics. We are here to look at the parameters and learn about quantum mechanics in brief. But before switching to it, we will understand the classical physics and the perspectives.

Classical Physics

The other name of classical physics is pre-quantum physics. It varies from the different types and perspectives of Physics. The term which differentiates this from the rest is that it is unlike the objectively real world. The properties and the existence varies. The notions and the ideas appear to the whole new world. Be it from Galileo, Newton and reaching towards Einstein and Laplace. The equations and the theories which they included are

  1. Maxwell Theory of the electromagnetic field
  2. Newtonian mechanics
  3. Einstein theory of general relativity

They actually described what is really happening in the world, that too explaining the physical system of the world.

We look for the motion of the particle moving through space. The most accessible example is the tennis ball flying through the air. It must have a definite position and velocity. Before these theories, monitoring the behavior is not necessary. In physics, we do not do guesswork. The measurement efforts and the perfect evidence are the two things which make the subject not so easy to understand.

Classical Randomness and Ignorance of Information

This discipline or area go for macroscopic objects. For such minute objects, measuring the positions and velocities is not possible. If we talk about to have an idea of the minuteness and the number of such particles, have a glance at the air in a bottle at room temperature. The number of particles whizzing at the top of the bottle is more than 25 powers of 10. Moreover, they are colliding with one another and also with the walls of the container. This leaves no chance for the measurer to have an idea of the speed and velocity of those particles.

Here comes erratic behavior, when we cannot have enough information to describe the speed and velocity of the particle precisely. The word randomly does not mean its dictionary meaning here. We perform experiments under the precisely identical conditions. This is why the predictability graph of the result is high and accurate. The level where we show some ignorance is at the end. That is why we cannot reach the exact solution and hence consider it as a random experiment.

Quantum Physics

The things and the minuteness which the classical physics is not able to understand comes under quantum physics. These are at the macroscopic level. For instance, the existence of stable objects, colour of the heated purpose and many more. What we observe here is the non-classical behavior of the microscopic system. That is atoms and molecules. Here are some of the behaviors which we need to know which the particles at the levels of molecules and atoms exhibit.

  1. Interference phenomenon
  2. Entanglement
  3. Intrinsic Randomness

What is Intrinsic Randomness?

Preparing any physical system in a way in which all the physical attributes get precise specifications and that too at the same time. For example, pinning down the momentum and the position of a particle at the same time is not possible. Finding both these traits needs a series of experiments. But we cannot do it at the same time. The velocity and the position varies.

It has an irreducible feature. It means that eradicating it in the experimenting technique is not possible. This shows the limits which nature puts on the physical system. It does not allow the man to have the complete set of information. This is the main difference between the classical and quantum physics. In the latter, getting to the precise level of the results is not possible.

Know about Interference

Sometimes the little physical systems do a mutually exclusive thing at the same time. Yeah, every student’s mind reaches to the two-slit experiment in which the electrons are fired at one time. It gets to the screen where we have two narrow slits. There is an observational screen placed beyond the screen. Those screens will have a slit on which the electrons will strike. The inference of this experiment is the arrival of electrons in the preferred locations. They observe a wave-like pattern.


When the particles spin precisely opposite to each other, then it is called total angular momentum is zero. Every spin is studied for speed, velocity. The research of the measurement is not that simple. The spins may either be equal or opposite. But we are not here to correlate the turns of the particles. But preparing the particles to spin in some states and the value of the spin is higher than the classical physics permits.

This was about the beginning of the subject quantum physics. In the next blog, we will reach observation, information, and the theories of Physics.