Quantum Physics

Quantum physics is the branch of physics that describes the behavior of matter 
and energy at the atomic and subatomic scales. It was developed in the early 
20th century to explain phenomena that classical physics could not.

Foundational Concepts:

Wave-Particle Duality:
Light and matter exhibit both wave and particle properties. The double-slit 
experiment demonstrates that electrons can behave as waves when not observed 
and as particles when measured.

Heisenberg Uncertainty Principle:
Proposed by Werner Heisenberg in 1927. It states that it is impossible to 
simultaneously know both the exact position and momentum of a particle. The 
more precisely one is measured, the less precisely the other can be known.

Quantum Superposition:
A quantum system can exist in multiple states simultaneously until measured.
Schrödinger's cat is a thought experiment illustrating superposition: a cat 
in a box is both alive and dead until the box is opened.

Quantum Entanglement:
When particles become entangled, the quantum state of one particle instantly 
affects the other, regardless of distance. Einstein called this "spooky action 
at a distance." This phenomenon was confirmed experimentally and is used in 
quantum computing and quantum cryptography.

Key Figures:

Max Planck (1858-1947): Introduced energy quanta in 1900, considered the father 
of quantum theory. Won Nobel Prize in Physics in 1918.

Niels Bohr (1885-1962): Developed the Bohr model of the atom in 1913, describing 
electrons in discrete energy levels. Won Nobel Prize in Physics in 1922.

Erwin Schrödinger (1887-1961): Developed the Schrödinger equation in 1926, which 
describes how quantum states evolve over time. Won Nobel Prize in Physics in 1933.

Applications:
Quantum physics underlies modern technologies including lasers, transistors, 
LEDs, and MRI machines. Quantum computers use quantum bits (qubits) that can 
exist in superposition, potentially solving problems classical computers cannot.