“Ladies and gentlemen I announce you the end of the physic. We all know all the nature rules and the secrets of the cosmic harmony“, said Lord Kelvin at the Royal Society in 1900. Only a few months later Max Planck wrote to his son a letter dated 12 October: “Dear Edwin, today I made an important discovery as Newton one“.

Planck discovered that a hot body makes radiation, not in a continuous way but divided, energy quanta, small and giving quantities. He talked about the universal constant, as quantum elementary action, or Planck coefficient that express the fixed value and not dividable in which the energy of a radiation is divided.

Einstein started to study hardly the quantum physic and he used the idea made by Planck to explain the laws of the photoelectric effect; the other development of the quantum mechanics  make the basis for the actual division about the General Relativity Theory made by Einstein used to Study the microscopic phenomena, instead the quantum mechanic is used to understand the level subatomic of the Universe.The incompatibility between these two theories is the problem that today afflict the modern physic.