Particles and Waves are the basic fundamental behavioural patterns of the infinite matter present in this universe, ranging from the smallest of the atoms to the largest of the matter objects. The wave-particle duality or the behaviour of matter as a particle or a wave is the fundamental concept or the base for the very interesting study of Quantum Mechanics.
Albert Einstein once said these following words, “It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty. We have two contradictory pictures of reality; separately neither of them fully explains the phenomena of light, but together they do.”
On the basis of those words, it can be inferred that light behaves as both as a particle and a wave, and coming to this revolutionary and changing statement for the classical physics took years and years of time.
If it was not for Albert Einstein in the year 1905, this phenomenon was not considered to be true and even this was taken from the theory suggested by Max Planck on the light emitted by hot objects, Einstein applied this theory to his iconic photoelectric effect theory to state that the light’s behaviour is not just a wave but can also be a packet of particles called as photons with energy imbibed within them. This idea of the photoelectric effect and the dual nature of light has made a serious impact on the formation of the model of the atom to explain it on the electrons as well.
Many renowned scientists such as Ernest Marsden, Hans Geiger and Ernest Rutherford collaborated and formulated the model of an atom only to achieve moderate success. it was then, the Danish scientist Neils Bohr to actually use the dual nature principality of the light on to the electrons to formulate the model of an atom even including the atomic mass and the atomic number within the concepts of the modern physics, a derivative of the classical physics.
The Bohr model combines the Planck and Einstein studies perfectly and also solves the problem of the emission of spectrum in the frequency and energy patterns of the electrons of the atom. The concern of the questions in the Bohr model of the atom in the inclusion of special orbits was solved by the French scientist Louis DeBroglie and also explained the actual reason of inclusion 0f these special orbits in the atom’s model and explained it in the DeBroglie’s Hypothesis.
Then after all these combined works and the years and years of hard work of the various scientists, The principles and the foundation of Quantum Physics was laid by Richard Feynman and thus this study came into existence into the modern physics we study and apply now.