Summary of "Introduction to Quantum Mechanics - I"

Quantum mechanics was developed in the early 20th century due to experiments like blackbody radiation, photoelectric effect, and discrete spectrum of atoms like hydrogen.

Quantum mechanics is based on five postulates that describe the behavior of particles, observable quantities, and the evolution of the system in time.

Postulate 1: The state of a quantum system is described by a wave function that depends on position and time.
The wave function represents the probability distribution of finding a particle at a certain position.
The wave function must be normalized, continuous, and finite.

Postulate 2: Observable quantities in Quantum mechanics are described by operators that act on wave functions.
operators corresponding to classical observables are obtained by replacing position and momentum variables with position and momentum operators.
Quantum operators must be linear, hermitian, and have eigenfunctions that form a complete basis.
operators without classical equivalents, like spin, exist in Quantum mechanics.

The Hamiltonian operator is crucial in Quantum mechanics and represents the total energy operator.
The angular momentum operator is obtained by replacing classical variables with position and momentum operators.
Quantum operators satisfy certain properties such as linearity, hermiticity, and completeness of eigenfunctions.

The Dirac notation is introduced to represent operators and their properties concisely.

Postulate 2 outlines the principles of quantum mechanical operators and their relation to observable quantities.