Hola, amigos.

In this brief post, I wish to outline the staggering developments in Quantum Physics that happened during the period that led to “the golden age of physics” and post golden-age developments till now.

Imagine yourself as one of the physicists, confident that you can see the light at the end of gentle, good night. You are convinced enough that physics is solved except for a few shortcomings. And then a couple of fine gentlemen come along and topple your world from bottom up.

First man is none other than Max Planck. Lot of prominent names like Lord Rayleigh and Lord Kelvin jump up in discussions on Thermal Radiation spectra and none of them capable of providing an acceptable explanation to Black body problem. The problem was that no existing theories provided calculations that fit the spectra of a black body, which is capable of perfectly absorbing all radiations and emitting none.

What does Max Planck say ? He says that maybe radiation is not all wavy and classical as much as we would like it to be. Maybe radiation is discrete. Maybe radiation is Quantized. A fundamental unit of energy and every radiation is just lumps of it. And that remarks the start of all things great.

Following the intuition, Einstein explains the photo-electric effect as a quantized phenomena. Therein lies the foundations of quantum theory. Bohr follows this further and develops his own theory of hydrogenic atoms, Sommerfeld expands it with his own modifications. Heads roll as both their pictures violate the principle of Electrodynamics, that Maxwell left strong and intact, namely, a moving charge cannot not radiate energy, so electron falls into the nucleus and atom goes poof!

It is only in edge of trials, do the best and brightest minds produce the best works of human lifetime. One such worthy contribution comes from Erwin Schrodinger, whose name, more often than not gets dragged through ruffle his cat situation. (I kinda hate schrodinger’s cat explanation of Quantum mechanics)

He says that, microscopic thingies do not obey classical frame of thought. You can do one of two things with them but never at the same time. But what you can do is work with probability and averages. He says that electrons in atom are not moving in circles or, more generally, any defined trajectories. This causes a grainy nature of phase space in symplectic manifold unlike the smooth fluidic classical picture. The last comment is a post for another day. We will look into complicated terminologies when we dive into Strings.

Erwin Schrodinger, like a badass, invents his own mathematics and correctly works out Hydrogen atom electron energies. Around that time, Born and Heisenberg develop their own formulation of Quantum mechanics. Heisenberg is only credited with Uncertainty principle in main stream media, rather his most impressive contribution was the Matrix Mechanics. You only get nobel prize for Rigorous Mathematical principles.

With this new tool, we could explain a lot of things. Very good theory. This gave birth to several fields like Condensed matter physics, Ultra cold atoms and optics. These fundamental principles bequeathed us with several experimental equipments, Electron microscope, X-rays etc.

Essentially there are two kinds of particles, fermion and bosons. They obey different statistics. Fermions have half odd integer spins and bosons have integer spins.

With everything there are, always, ifs and buts. This theory has a very big if and but.

Theory works good, but, we are still unable to explain a lot of things. Before that, Einstein, the rock star that he totally is, came up with Special relativity. He says that any valid theory should be lorentz variant. And surprise, surprise QM is not lorentz invariant. Einstein also says that Energy and Matter are the same. Both are interconvertible. We see that particles can be created and destroyed with sufficient energy. But this is not allowed in the scope of QM. And there is another fundamental question lurking. What really is spin ? What are fermions and how much different are they from bosons ?

Unfortunately, our blog post ends here, these shall be the matter of discussion in my post on Quantum theory of Fields. I shall try to convince you guys, why fields make more sense than particles. No later than that, I will argue why one should abandon fields for all and why strings and loops make much more sense !

I should remark why Einstein has the imperial status of, well….Einstein. The notions of Special and General relativity conceived by our bro Stein man exposed the lacking principles of theories that have been successful for a century and we are still battling with his second strike.

How he managed to conceive those ideas in a time so far behind, is entirely beyond me !