The development of quantum theory is one of the greatest  revolutionary achievements of the twentieth century in the history of science. Quantum Theory was developed by the well known physicist Max Planck. In December 1900, Planck established a theory regarding absorption and emission of energy by matter in the form of radiation which in 1901 became famous as quantum theory. This was entirely different from the theories of classical physics developed mostly by Sir Isaac Newton. During whole of twentieth century and till now quantum theory has revolutionized biology, medicine and engineering. Because of quantum theory it became possible to discover and explain new galaxies of experiments.

Before we describe more about Max Planck it is necessary to know something about quantum theory.  Although it is difficult to explain this theory in a laymen’s language, we can say that electromagnetic radiation such as ordinary visible sun light is absorbed by matter only in the form of discrete packets.  The amount of energy in a packet depends on the frequency of radiation. This packet of energy is called quantum.                     Quantum is a Latin word which means quantity. One quantum of light is called a photon. The quantum theory devised by Max Planck was so difficult that in the beginning only Albert Einstein could understand its importance.  On the basis of this theory he explained the pheno- menon of photoelectric effect. There was a time when scientists were not ready to a accept the quantum theory of Max Planck, but later they realized that it was the only theory which can resolve every problem of physics and chemistry. Later famous scientists like Albert Einstein, Neil Bohr, Debroglie, Rutherford, Davisson, Pauli, Heisenberg,  Schrodinger strengthened the base of this theory which has now become an integral part of physics and chemistry. 

The father of quantum theory Max Planck was born in  Kiel, Germany on April  23, 1858. His father, Julius Wilhelm was a professor of law in Kiel University. Later he joined Gottingen University. He was mainly educated in Munich and Berlin Universities.  In Berlin University he worked with Kirchoff and Helmholtz who were world famous scientists.  In 1879 he did his Ph.D from Munich University. From 1880 to 1885, he taught physics  in this university. The revolutionary ideas regarding quantum theory were induced into his mind by Kirchoff. After 1885, Planck became associate professor of physics in Kiel University where he worked for four years. In 1889 he was appointed professor of physics in Berlin University in place of Kirchoff and he held this position till his retirement.

Planck started his research in the field of thermodynamics with the inspiration from Kirchoff.  Because of his deep involvement in this subject he published several research papers related to thermodynamical problems. While studying thermodynamics he was also trying to solve certain problems related to radiation physics. During these studies. He tried to find out a relationship between the energy distribution with the different colours of light. The results he obtained from the study of radiation from the black body were markedly different from the findings of classical physicists. After continuous research he was able to establish a relation between energy and frequency of radiation.  His findings were published in 1900 which later became the basis for famous quantum theory of radiation. He proved beyond doubt that the apparently continuous radiation is in fact made up of small packets of energy. 

Max Planck received many honorus and award.  In 1918, he was awarded the Nobel Prize in physics in recognition of his quantum theory. In 1926 he was elected the fellow of Royal Society of London and in 1928 he was given the Koopley Medal of Royal society. He was later appointed  as  the president of Wilhelm Cancer Society for popularization of Science.  Meanwhile the political condition of Germany became very miserable under the dictatorship of Hitler and his Nazi government.  Max Planck had to face many difficulties in the regime of Nazi government.  In fact it was the most painful period of his life. He wanted to serve his country, but the policies of  Nazi government were against the Jews. He got the biggest shock.  In 1944  his son was hung for a false allegation of planning the murder of Hitler. After this event he became totally depressed.  During world War-II, his houses was destroyed by a bomb explosion.

On October 4, 1947 this world famous scientist passed away  in Gottingen.  He was not only  most respectable  for his scientific achievements, but at the same time  for his personal qualities.  He was very fond of music.  In fact once he had decided to take up music as his career.  As a mark of respect to him, a constant has been named as Planck’s constant (h) which is often used in physics,  chemistry and quantum theory.