May 29, 2024
Classic physic theories have and are been tested countless times and they appear to describe reality quiet adequately. It wasn’t long until these theories came falling apart.

The first phenomenon which classical physics failed to explain is The Black-Body Radiation. So, first of all to understand black-body radiation, it is necessary to understand that all tangible material in the universe, or should I say multiverse :-D, emit or absorb energy in the form of electromagnetic radiation. The amount of energy that is absorbed or emitted differs due to various factors like the temperature of that body. Higher the temperature, the higher the average frequency(therefore energy) of electromagnetic radiation emitted by a body. Most of the time we cannot see the energy emitted or absorbed as usually bodies at room temperature emit predominantly light from the infrared spectrum. We can only see when visible light is emitted, for example, when metals melt we see them glow – as they reach a very high temperature emitting lot of light, and thus it glows and we can see it.

Physicist of the 19th century were trying to establish the spectral composition emitted by a body in relation to its temperature. So to accomplish that, they made use of a black-body. A black-body is a hypothetical body which needs to meet the following conditions:

  1.  A black body absorbs all electromagnetic radiations that strike it (electromagnetic radiations include gamma, x-ray, ultraviolet, visible light, infrared, microwave and radio wave).
  2. A black body stays in thermal equilibrium with its surroundings (i.e. all bodies in the same system have the same temperature which is also equal to the temperature of the system).
These conditions ensure that the energy emitted by the black body solely depends on its temperature. However, when the physicists tried to establish the composition of the energy spectrum emitted using classical physics, results didn’t coincide with reality.
According to classical physics the black body would emit the same amount of light of each frequency. However, the higher the light’s frequency, the more energy the light has. Therefore a black body would emit infinite quantities of energy in form of high-frequency radiation. If this classical physics explanation was true then it would have dire consequences – it basically states that every single object in the universe should immediately emit all of its energy in the form of UV. Luckily, the universe is a complex system and doesn’t work in that way,otherwise we wouldn’t exist.
This realization carved a huge milestone for the evolution of modern science. Physicists were forced to admit classical physics were wrong. Today, we have a name for this colossal failure (but a learning step) of classical physics — The Ultraviolet Catastrophe.
The black body radiation problem was solved by a brilliant German physicist Max Planc. He came with a simple and elegant idea that bodies do not emit electromagnetic radiation continuously, but via small packets called quanta. The size of these quanta is given buy :
 E = h * f 
(h = 6.626 * 10-34 Js)
E = energy
h = plank’s constant
f = frequency of radiation
The electromagnetic waves can be essentially thought of a set of energy packets whose total energy determines the energy of the wave itself. The size of the quanta is specific to each wave. As seen from the equation – higher the frequency of radiation, higher the size of energy in a quanta (larger quanta). This solves the black body problem – it is increasingly difficult for a black body to emit higher frequency radiations as it cannot usually “feed” on high frequency quanta with enough energy, and thus sticks with low energy light.
Quantization of energy means that a energy is quantized into small packets, quanta, instead of a wave. This is just the beginning of the whole new interesting, diverse and deep world of physics.

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