Question

Explain quantum theory?

Answer 1

In 1900, physicist Max Planck presented his quantum theory to the German Physical Society. Planck had sought to discover the reason that radiation from a glowing body changes in color from red, to orange, and, finally, to blue as its temperature rises. He found that by making the assumption that energy existed in individual units in the same way that matter does, rather than just as a constant electromagnetic wave - as had been formerly assumed - and was therefore quantifiable, he could find the answer to his question. The existence of these units became the first assumption of quantum theory.

Planck wrote a mathematical equation involving a figure to represent these individual units of energy, which he called quanta. The equation explained the phenomenon very well; Planck found that at certain discrete temperature levels (exact multiples of a basic minimum value), energy from a glowing body will occupy different areas of the color spectrum. Planck assumed there was a theory yet to emerge from the discovery of quanta, but, in fact, their very existence implied a completely new and fundamental understanding of the laws of nature. Planck won the Nobel Prize in Physics for his theory in 1918, but developments by various scientists over a thirty-year period all contributed to the modern understanding of quantum theory.
Dual Behavior of Matter:

This is mainly because the behavior of macroscopic object is practically particle in nature, they do have wave nature but it is negligible because of their huge masses; whereas on the other hand the atomic level particles have very less mass and hence both particle and wave nature is prevalent in them. This dual behavior of displaying both particle and wave nature is known as dual behavior of matter and for every particle, the particle nature comes from its mass and the wave nature comes from its matter wave defined by De-Broglie relationship which is given by,

λ = h/mv

Where,

λ = wavelength of the matter

h = plank’s constant

m = mass of the matter

v = velocity of matter



Classical physics hasn’t been able to explain the dual behavior of a matter and Heisenberg’s uncertainty principle, according to which the position and momentum of a sub-atomic particle can be calculated simultaneously with some degree of inaccuracy. Hence, there was a need of new theory that could explain the behavior of atomic and sub-atomic particles.

So, this led to the birth of quantum physics – It is a branch of science that explains the physical phenomenon by microscopic and atomic approach and takes into account the dual behavior of matter. It is theoretical physics and it specifies the laws of motion that the microscopic objects obey. When quantum mechanics is applied to macroscopic objects (for which wave like properties are insignificant) the results are same as those from the classical mechanics.