Evolution of Quantum mechanics, A quick Summary

 The most significant development in science has happened in the last 100 years and definitely, it's something we can't deny. The last 100 years have been very very important for modern physics and technology because not only was our knowledge challenged but also, reality transformed for humanity in such a way that we can't really even look back without appreciating the efforts of some influential group of scientists that changed the way that we see the world. 

It is believed that the 1st ever experiment that later became the foundation of quantum mechanics is the most famous experiment, Young's double slit experiment in 1803. Thomas Young is one of the most brilliant minds that the world of science has gotten. He started off as a Physician and something about waves and light always intrigued him. In his career as a physician, he was the first one to notice that the shape of the human eye changes to focus the light incident on the eye at varying distances from the source. Young always suspected that light is a wave and he noticed the interference of the sound waves so he believed if the light is a wave then it must as well follow the phenomena of interference and the rest is history. For the 1st time, there was concrete evidence of light being a wave and nobody had no idea how to respond to such a miraculous discovery. 

However, there were still many phenomena that the wave nature of light couldn't explain which caused instability and conflicts about the idea of light and the world was divided. While this was happening, another brilliant scientist Gustav Kirchoff started questioning the thermal radiation emitted by different objects. He concluded that the emission spectrum of a body is only dependent on its temperature. Well, he couldn't really develop a mathematical equation to describe the curve that would really fit the curve and also explain the working principle behind it. The fun part is the idea of the wave nature of light, which dominated the world then, was taken into consideration to explain these phenomena and we know they couldn't explain it. Wilhelm Wien, Lord Rayleigh, and James Jeans, they had their separate attempt to explain the phenomena and derive the law of radiation but in some way or the other, they were missing out on something or I would say, neglecting the previous idea of radiation and light. Max Planck, another brilliant physicist, was really intrigued by his colleague Wilhelm Wien's work on trying to explain the spectral energy density of a black body in the different wavelength spectrums. Although it was highly successful in explaining the phenomena at higher frequencies, it deviated very much from the experimental data at smaller frequencies. Planck jumped in and tried to express the radiation formula by considering the particle nature of light. He considered the light to be made up of many tiny energy packets, known as Photons, and derived an expression for the radiations emitted by black bodies which accurately matched with the experimentally obtained curve with the least error and deviation. 

Well, here we go again!

Planck did it and it is as if the idea of the particle nature of light was revived from its burial at the grave of Thomas Young. Not only this, there was a simultaneous attack on the theory of the wave nature of light when Albert Einstein explained the photoelectric effect with the help of the particle nature of light. But like the joker in a deck of cards, there were many other phenomena of light that the wave theorist of light put against the particle theory and they won. So you see, the wave nature and particle nature of light are like 2 logical neighbors fighting for their popularity in a society of intelligent beings. Then came Albert Einstein, the messiah of the 2 groups, and said, nope! you both are popular and important in your own ways, jhagadna band karo! And that's how we concluded that light possesses dual nature, both as particles and as a wave. Well, why don't we spend some time discussing how such topics have helped the modern world and evolved the technology around us? Starting off with the Photoelectric effect, the most promising aspect of the future is renewable and clean energy. The discovery of the Photoelectric effect has helped the world to make energy out of the cleanest source of energy we have, the sun. Let's ask what Dr. Octavius has to say about this one?

Definitely Doc! It is indeed true. The basic underlying principle of working solar cells is the Photoelectric effect and the study of black body radiations has helped us in developing black bodies for lighting, heating, security, thermal imaging, etc. About the wave nature of light, there are many applications such as optical testing that helps the world by providing good optical instruments for research and medical purposes. Now let's move on to further developments.

Well, the next thing is the discovery of the dual nature of matter. When Young's double slit experiment was performed for a beam of electrons, it was seen that, unless observed, they started forming an interference pattern. How ODD? I mean, interference was a wave phenomenon right? and electrons are particles? Davisson and Germer performed an experiment in 1927, in which electrons, scattered by the surface of a crystal of nickel metal, displayed a diffraction pattern and it proved the de-Broglie hypothesis of the dual nature of particles

Now, scientists started implementing the idea of waves and the particle nature of matter. The famous Heisenberg uncertainty principle, Schrodinger's wave formalism for quantum mechanics, Heisenberg's matrix method, and Dirac's bra-ket notations gave a push to the development of quantum mechanics as we just tried to explain the quantum mechanical phenomena with the help of mathematical models. This led to many more discoveries and explanations to them. The development of quantum mechanics lead to the development of nuclear physics, atomic and molecular physics, condensed matter physics, and Chemistry and as years passed on, we got an in-depth understanding of things that just didn't make sense. Even though the theory of quantum mechanics is just insanely beautiful that no one has ever claimed to have truly understood it but they definitely praise its beauty. 

But I have been speaking a lot about the things that we know, I know and it is just to revisit those days and appreciate the works that led to the development of such a beautiful concept. Coming back quickly from the nostalgia phase, Quantum mechanics has provided answers to many problems that have led to the development of many other sectors. Functioning of the transistors, and lasers, when we go for an MRI Scan of our body and of course, the devices to which our life has been deeply attached our cellphones and laptops.

And how can we forget about the modern marvel? Quantum computing! It was first proposed by Dr. Richard Feynman and Dr. Yuri Manin and it was just because of the failure to render simple quantum mechanical models by mankind. You see, a particle can exist in multiple states in a quantum mechanical system. Unlike classical probability theory, these many configurations of the quantum state, which can be potentially observed, may interfere with each other like waves. This interference prevents the use of statistical sampling to obtain the quantum state configurations. Rather, we have to track every possible configuration a quantum system could be in if we want to understand quantum evolution.

To store just 40 quantum states of a system of electrons, we may need 130GB of storage which is not impossible but not advisable as well. And for a system of a few hundred electrons, the computational storage required may exceed the total number of particles present in the whole universe, So good luck with studying their dynamics.

Anyways, Quantum computation although looks like a fairy tale, is a reality today. We suffer a lot when it comes to handling a very large amount of data. According to Domo, computing devices generate around 2.5 quintillion bytes of data daily. Modern computers and supercomputers are prone to errors when handling such a massive quantity of data, affecting performance. However, Quantum computers can process large volumes of data very fast which makes them more efficient and error-free than our classical computers and supercomputers. Quantum computing can play a crucial role in drug development, wherein drugs can be tested for stable molecular configuration using molecular modeling processes. Also, quantum computers can run advanced simulations on various participating organic molecules that help decide the suitability of the organic molecules for the drug. During the covid 19 pandemic, it was very hard for researchers to create a protein model to study the virus properly which resulted in the delay in the creation of its vaccine. Quantum computation has applications in the field of aerospace, finance, cyber security and etc.

How did we come up with this from the phenomena of interference of waves is beyond amazing to me! Humankind has evolved this far and will keep continuing to evolve better to understand this universe. Maybe to a larger problem, we have to go really small, down to the quantum realm to understand its solution. The evolution of quantum mechanics is simply beautiful and with this, I would like to sign off, 

thank you!