Elementary Quantum Theory of Max Planck

One of the biggest surprises of 20th century physics was the discovery that classical mechanics (the mechanics of macroscopic particles) is an approximation it is inapplicable to like size of atoms and has to be replaced by Quantum Mechanics. Until the present century it was assumed that the classical mechanics was applied to objects as small as atoms. Experimental evidence was accumulated, however, which showed that classical mechanics failed when it was applied to very small particles. Classical physics was thought to be wrong in allowing systems to posses arbitrary amounts of energy. When this key idea was pursued quantum mechanics was discovered and it was in 1926 when appropriate concepts and equations were discovered to describe the new mechanics Quantum Mechanics. 

Max Planck (1901) proposed a revolutionary hypothesis in which he discarded the precept that an oscillator emits or takes up ener continuously and suggested that ener changes occur in discrete amormts. 

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