Who first enunciated the Quantum Theory?

The quantum theory was first enunciated by Max Planck, a German physicist, in the year 1900 — a moment that completely revolutionised the world of physics and marked the birth of modern quantum mechanics. Planck introduced the radical idea that energy is not emitted or absorbed continuously, but rather in discrete packets called quanta (singular: quantum). This was a groundbreaking departure from classical physics, which had always assumed energy to be continuous. Planck proposed this theory while trying to explain the black body radiation problem — a puzzle that classical physics had completely failed to solve.

• Planck's Constant: Planck introduced the famous constant h = 6.626 × 10⁻³⁴ Js, which defines the size of each energy quantum and remains one of the most fundamental constants in all of physics
• Quantum Formula: Energy of a quantum is given by E = hν, where h is Planck's constant and ν is the frequency of radiation
• Black Body Radiation: Planck developed quantum theory specifically to explain why heated objects emit radiation in a specific pattern — something classical physics could not explain
• Niels Bohr: Used Planck's quantum theory later to develop his atomic model explaining electron energy levels
• Albert Einstein: Extended quantum theory in 1905 to explain the photoelectric effect using the concept of photons — but the original quantum theory belongs to Planck