- Origin of Quantum Physics
- Wave function
- Collapse of Wave Function
- Physically Accepted Wave function
- Normalization Explained
- Method of Normalization
- Orthogonality & Orthonormality
- Hilbert Space
- Quantization Rules
- Operator Formalism
- Commutator Bracket
- Linear Operator
- Hermitian Operator
- Projection Operator
- Unitary Operator
- Parity Operator
- Expectation Value
- Schrodinger Equation
- Wave-Particle Duality Using Schrodinger Equation
- Superposition of States
- Various Representations of Wave Function
- Probability Current Density
- Uncertainty in Operators
- Shortcut for Calculating Momentum Expectation Value

Quantum physics, also known as quantum mechanics, is a branch of physics that deals with the behavior of matter and energy at the atomic and subatomic level.

**The Begining**

The origins of quantum physics can be traced back to the early 1900s, when scientists began to study the properties of atoms and their constituent particles.

**Max Planck**

One of the key figures in the development of quantum physics was Max Planck, a German physicist who in 1900 proposed that energy is not continuously distributed, but instead is emitted in discrete packets, now known as quanta.

This idea was a fundamental departure from classical physics, which had long held that energy was a continuous quantity.

**Niels Bohr**

Another important figure in the development of quantum physics was Niels Bohr, a Danish physicist who proposed the “Bohr model” of the atom in 1913.

In this model, the electrons in an atom are restricted to certain orbits around the nucleus, and can only transition between these orbits by emitting or absorbing a quantum of energy.

This model was able to explain many of the properties of atoms that had previously been mysterious, such as the spectrum of light emitted by atoms.

**Werner Heisenberg & Erwin Schrödinger**

In the 1920s and 1930s, several other physicists made significant contributions to the development of quantum physics.

Among them were Werner Heisenberg, who proposed the uncertainty principle, which states that it is impossible to know both the position and momentum of a subatomic particle simultaneously.

Erwin Schrödinger, who formulated the wave equation that describes the behavior of subatomic particles; and Paul Dirac, who developed a relativistic wave equation for electrons.

**Impact on Classical Physics**

The development of quantum physics also had a profound impact on our understanding of the nature of reality.

In classical physics, objects have definite properties, such as position and momentum, that can be measured with arbitrary precision.

However, in quantum physics, the properties of subatomic particles are described by wave functions, which can only be used to calculate the probability of finding a particle in a certain location or with a certain momentum.

This probabilistic nature of quantum physics has led to much debate and discussion among physicists, and is the subject of ongoing research.

**Summary**

In conclusion, quantum physics has its origin in the early 1900s, with the contributions of many scientists, including Max Planck, Niels Bohr, Werner Heisenberg, Erwin Schrödinger and Paul Dirac.

The development of quantum physics has led to many new insights into the nature of matter and energy, and has had a profound impact on our understanding of the universe.