Einstein had also made contributions to the development of the quantum theory. The concept of light quanta (photons) was used by him in 1905 to explain the Photoelectric Effect and to develop the quantum theory of specific heat.
Despite playing a main role in its development, Einstein regarded the quantum theory only as a temporarily useful structure.
His efforts were primarily in formulating the unified field theory which he believed would turn out to be the reason behind quantization of energy and charge. He felt that the quantum theory lacked the simplicity and beauty befitting a rational interpretation of the universe.
He engaged in a series of private debates with physicist Niels Bohr about the validity of the quantum theory later on. The 1920s witnessed his prolonged public debates with Niels Bohr and Werner Heisenberg over quantum mechanics. Einstein was rather lukewarm about the quantum theory even from a philosophical standpoint, saying in 1926 that he was convinced God does not throw dice. However, Bohr showed the ambiguities in Einstein’s reasoning.
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