A brief history of quantum mechanics

Over a century ago, attempts to explain certain physical phenomena using classical physics failed. Why do atoms radiate only certain colours? Why does light sometimes behave like a wave and sometimes like particles? Quantum mechanics provided the answer: energy and matter do not exist in one continuous form, but as tiny portions – the quantum.

Without quantum mechanics, there would be no lasers, no computer chips, no GPS. Nowadays, quanta are indispensable to metrology, the science of measurement. Units such as the second, the kilogram or the ampere are based directly on the natural laws of quantum physics.

Beginning of quantum mechanics

In 1900, Max Planck introduced the idea of energy quanta. Shortly thereafter, Albert Einstein postulated that light also has particle properties and that the energy of these particles (now called photons) is quantised. He used this theory to explain why only light of a certain frequency is emitted by electrons in metals. Later, researchers such as Schrödinger and Heisenberg successfully created theories explaining which laws and equations matter follows at atomic levels. This laid the foundation for modern quantum physics. Today, quantum mechanics is one of the best-proven theories in science.

Quantum revolutions

First quantum revolution (1900–1950): Foundations laid, theoretical understanding and initial applications such as semiconductors and lasers.

Second quantum revolution (today): Control over quantum systems paves the way to new technologies – quantum computers, secure communication and extremely sensitive sensors.