Quantum Reality: Understanding the Microscopic World

We all have heard the word ‘Quantum’ at some or other point in our life. If you haven’t then you are from some other universe. We all have heard about it despite the fact that most of us don’t know anything about it. Some of us might know ‘what’ it does, but nobody knows ‘how’ it does whatever it does. The Great Physicist and Nobel laureate Richard Feynman once said, “I think I can safely say that nobody really understands Quantum Mechanics.” So let us try to understand why such a great physicist like Feynman said such a thing.

What is Quantum?

First of all, let’s try to understand what quantum physics is all about. You might have heard something about a “quantum battery” which is supposed to run forever without any loss of energy or “quantum vehicles” which runs faster than the speed of light. Believe me, that’s not what quantum means. That doesn’t even qualify to be called quantum at all. Quantum Physics in a sense is the study of microscopic objects. When we go to bigger and bigger scales, we tend to call objects less and less quantum, i.e. classical, that’s why classical physics is the study of macroscopic objects.

How it all started?

Quantum physics is the best description of how nature works. It gives the best description of anything you can come across while performing an experiment. So let’s take a look at how it all started.

John Dalton proposed the theory of atoms, i.e. everything in the universe is made up of small indivisible particles called “atoms”. Later it was found that they are not indivisible but are composed of protons, electrons, neutrons, etc. And the picture of the atom we had was something like this

The same thing which we have in our thehavok logo. It described the motion of electrons around the nucleus just the same way planets move around the sun. But this model has many drawbacks and was discarded and upgraded many times in history. The origin of quantum mechanics can have two paths:

1. Einstein stating that light shows both particle and wave behaviour.
2.  De Broglie and Schrodinger stating that everything in the world shows both particle and wave behaviour. It behaves as a wave when don’t look at it, and as a particle when you look at it.

 A few years later, Erwin Schrodinger comes up with an equation which tells you how it all works.

He said that we have something called a wavefunction (𝛹) which is spread everywhere, but when we look at it, it gets localized and gives an outcome of the experiment and the above equation tells you how it evolves with time. This is the beginning of the quantum era.

What it all means?

There had been long debates between philosophers and physicists about all this. But most of them are due to the fact that we are still stuck to the language of “cause and effect” (you can read about it in my previous article “Physics and it’s not so popular language“), but the laws of physics do not speak that language, they speak the language of mathematics.

Even though mathematics was created by the human mind, its remarkable effectiveness in explaining the world does not extend to the mind itself. If you ask a physicist what is the meaning of all these equations in quantum mechanics textbooks, he will simply tell you that he doesn’t know. What he can certainly tell you is that if you perform a certain experiment, what is the probability of getting a given outcome.

Does this mean that the world is probabilistic, i.e. one of the possible outcomes of many? Well, we simply don’t know. There had been many interpretations of quantum mechanics. Two of which we will talk here are,

1. Copenhagen interpretation
2. Many world interpretation.

Copenhagen interpretation

Suppose you want to study the physics of an electron and its position in a certain situation. To describe the electron, we have something called the wavefunction(𝛹) which is spread everywhere.

The value of |𝛹|² at each point will give you the probability of finding the electron at that point. When you measure the position of the electron, the wavefunction collapses at a single point and you will come to know where the electron is.

Or

But this interpretation has “measurement problem”, i.e. what do you mean by measurement? How does the collapse happen? How quickly does it happen? The answers to all these questions are unknown.

All these questions can be solved by new alternative interpretations, like the many world interpretation.

Many world interpretation

There are three points to get started with this interpretation.

1. The state of a quantum system is in superposition with all the states, i.e. to say the wavefunction is spread everywhere in Copenhagen interpretation. 
2. You (as an observer ) are a part of the quantum mechanical system.
3. You (observer) are entangled with the system, i.e. to say, we don’t have different wavefunctions for different things but we have a single wavefunction of the whole world.

Now you put the wavefunction in the equation and let it evolve. When you do the measurement, you see a result which is one of all the possible results.
Eg: you toss a coin, there are two things which can happen.

1. Coin reads “head” and you read “head”.
2. Coin reads “tail” and you read “tail”.

There can’t be a third possibility until and unless you are drunk.

So when you do the measurement and if you get “head” then you know which part of the wavefunction you are present in, in some other world there is another you(the observer) who gets “tail”. There is nothing like a collapse or something. This is the many world interpretation of quantum mechanics. If you ask me which one of them is “real”, then the most honest answer that  I’ll give,

“One of the best-kept secrets of science is that physicists have lost their grip on reality”

-Nick Herbert, Quantum Reality