# What is the Fermi-Dirac Statistics? (Q&A Session)

In this article, we will write in a Q&A (Question and Answer fashion which will help the readers understand the subject thoroughly.) This Comes under Particle Physics.

## 1. Who was Fermi?

Enrico Fermi was an American Physicist who had major contributions in the field of Quantum Mechanics, Statistical Mechanics and Particle Physics. He is considered to be the man who built world’s first nuclear reactor. Want to know more about Nuclear Reactors, check the following link

## 2. Who was Paul Dirac?

Paul Dirac was a British physicist born in Bristol. He was known for his contributions like Dirac constant, Dirac equation, Dirac operator etc. He found out the importance of spin as he cited that the spin in quantum mechanics is an effect of relativity. More about Paul Dirac here

## 3. What is a Fermion?

Being in the category of elementary particles, Fermions are indistinguishable particles with half-integer spin (1/2, 3/2, 5/2, …). Fermions are very light and tiny, e.g., electrons, protons and neutrons. Fermions are the particles that are in the Fermi-Dirac statistics as they obey a certain rule as per the statistics, i.e., Pauli’s exclusion principle. More about Fermions here

## 4. What does Pauli’s exclusion principle state?

It states that no two fermions can be in the same quantum state at the same time. For example, electrons or protons cannot be at the same quantum state simultaneously as they are fermions. Bosons don’t obey Pauli’s exclusion principle. For fermions, each of the available discrete state can be occupied by only a single particle. It’s strictly the basis of Fermi-Dirac Statistics. The principle was proposed by Austrian physicist Wolfgang Pauli. Pauli’s exclusion principle divides the subatomic particles into two different categories for their statistical behaviour. One that obeys Pauli’s exclusion principle (Fermions), and one that doesn’t (Bosons).

## 5. What are some examples of Bosons?

Bosons are the subatomic particles that obey Bose-Einstein statistics. They don’t obey Pauli’s exclusion principle as described above and they have integer spin, unlike fermions which have half-integer spin. Bosons are the particles that carry some force and energy. One of the examples of a boson is a Photon. As we know, photon is the carrier of electromagnetic interaction. It helps mediate electromagnetic force. Gluons are bosons that carry the Strong force, and W&Z bosons carry the Weak force.

## 6. In the end, what is Fermi-Dirac Statistics?

Fermi-Dirac statistics takes a system of indistinguishable and identical particles and make them distributed among a set of energy states. It almost works on the concept of probability. There is also an energy level that is called the Fermi level; a hypothetical level of energy of an electron. Fermi level will have a ½ probability or 50% probability of being occupied at any given time at thermal equilibrium. These statistics are allowed for fermions only, not bosons.

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Author: Som Abhisek.