TED Talks

I know a lot of people who watches TED talks, and most of the days I, indeed, try to watch at least one interesting talk I have found irresistible to watch. There are a lot of joy in the stories and also one the speakers. The talks are in wide broad from science, fascinating facts even on how to tie your shoe lashes. I strongly suggest to search or go to main page and look at already smartly labeled talks like

• ... persuasive
• ... courageous
• ... ingenious
• ... fascinating
• ... inspiring
• ... beautiful
• ... funny
• ... informative

The motto of TED is IDEAS WORTH SPREADING.

One talk I found interesting...

The stories of Murray Gell-Mann, Freeman Dyson

I stumbled on a great website where experts tell the story of their life, and besides of Nobel Prize winners, there are great physicists. I have found outstanding stories like Freeman Dyson, Murray Gell-Mann, and Hans Bethe. I strongly suggest watching, since it is also my research area, especially the speeches on the development of Quantum Field Theory.

I would like to express my difficulty of learning QFT even though there are so many resources on it, it really takes time and study to understand the idea behind every calculation/computation or idea. Also why it is invented and the way of thinking of the inventor.

Finding that great website on the stories of great experts on physics was really helpful for me because I, usually, go and read the original papers.

Here some interesting videos I have found interesting . . .

Freeman Dyson's Work

Murray's Gell-Mann: The Sakata Model
                                  Sheldon Glashow Model
Hans Bethe: The Bethe-Heitler Formula
John Wheeler: Witnessing the explosion. Edward Teller's seismograph

Pierre Louis Maupertuis

Pier Louis Maupertius

In my spare times usually, I look at the work of mathematicians and physicists of old times and seek the original papers just to understand what was in the mind of the writer. It is still under debate who earns the credit, but Maupertius is the one who first formulated the Least Action Principle. After a little search, I found the English translation Accord between different laws of Nature that seemed incompatible (1744) and Derivation of the laws of motion and equilibrium from a metaphysical principle (1746).

Therefore, I would like to stress that even though the least action principle initially is formulated for the equation of motion of a mechanical system. Later by Hamilton and Lagrange developed the Hamilton and Lagrange formulation of classical mechanics. In 20th century Schrödinger used the principle to write down the famous wave equation for de Broglie waves which is Schrödinger Equation. The interpretation of the Schrödinger equation led to the probability waves in the atomic world and the birth of quantum mechanics. The same principle is also applied in the development of Relativity. Last but not least, it plays the essential role in the development of Quantum Field Theory.

Here the life of Pierre Louis Maupertuis, the one who formulated the Least Action Principle in Wikipedia.

It would also be nice to mention French mathematician Lagrange who formulated the known by his name the Lagrange formulation of classical mechanics. His original work in French (it would be really nice if somebody points to the English translation), and autobiography. Lagrange solves the system in 2nd-order differential equations in n-dimensional configuration space. The configuration space is simply defined as the degrees of freedom in the system.

The Original Derivation of Schrödinger Equation

Taken from wikipedia:

In January 1926, Schrödinger published in Annalen der Physik the paper "Quantisierung als Eigenwertproblem" [tr. Quantization as an Eigenvalue Problem] on wave mechanics and what is now known as the Schrödinger equation. In this paper he gave a "derivation" of the wave equation for time independent systems, and showed that it gave the correct energy eigenvalues for the hydrogen-like atom. This paper has been universally celebrated as one of the most important achievements of the twentieth century, and created a revolution in quantum mechanics, and indeed of all physics and chemistry.

A second paper was submitted just four weeks later that solved the quantum harmonic oscillator, the rigid rotor and the diatomic molecule, and gives a new derivation of the Schrödinger equation.

A third paper in May showed the equivalence of his approach to that of Heisenberg and gave the treatment of the Stark effect.

A fourth paper in this most remarkable series showed how to treat problems in which the system changes with time, as in scattering problems. These papers were the central achievement of his career and were at once recognized as having great significance by the physics community.

The English translation of these papers could be downloaded HERE.

Lebesgue Integral and Fubini Theorem

Lebesgue Integral:         $F(x)=\int_0^xf(y)dy$


Fubini Thorem:              $\int_a^b\int_c^df(x,y)dxdy=\int_c^d\int_a^b f(x,y)dydx$


If one day, for some reason, you need to calculate double integrals and the integral is a kind of Lebesgue Integral defined above. You simply want to change the order of integration. Then, you need to use Fubini theorem.  One simple example is given below:

$\int_0^1\int_0^xf(y)dydx=\int_0^1\int_y^1f(y)dxdy$

But, to be able to apply the Fubini theorem, you have to note that If the double integration is defined as $\int_a^b\int_c^df(x,y)dxdy=\infty$ then $\int_a^b\int_c^df(x,y)dxdy\ne \int_c^d\int_a^bf(x,y)dydx$. For more information and step by step example is given in this video.

Introduction to Quantum Field Theory

In the 20th century, the first paradigm in physics was the probabilistic approach to the interaction of particles in the atomic world. Since then quantum field theory (QFT) for the interaction of particle fields via force fields is developed. Undoubtedly, to solve the equation of motions numerous advanced techniques are also developed. I use quantum field calculations to get the probability (amplitude) of various kind of interaction between the elementary particles. Then, compare the results/implications to the experiments.

I spent a lot of times on studying QFT, and there are still a lot of things to learn. Indeed, I do that every day. After the revolution of the www, or should I say search machines like Google, it is much easier to reach the information you seek. I have found a lot of resources on QFT, many of them are downloaded, and wait to be reviewed, and many of them are done. Along the way, since, it is in the nature of learning that you think you understand the idea by putting it in the pre-learned concepts in your mind. But, most of the time you do not get the concept/idea entirely, and just fill in the blank areas in time. It also possible that you misunderstand some of it. By solving problems, re-reading the textbooks and other resources it is possible to correct the mistakes and the blank areas in your mind. Then, you understand/learn the concept. Therefore, it is vital and a strong requirement for you to read as many resources as you find, repeat all the steps in the proofs so that you could be on the shoulders of the giants before you.

Here I have gathered a list, where you can find valuable lectures on QFT, either you can watch and read.

Books and Text:

1. Quantum Field Theory by de Wit
2. Introduction to Quantum Field Theory by Peskin and Schroeder
3. http://theory.fi.infn.it/casalbuoni/

Videos

1. Quantum Field Theory by Bernard de Wit @ CERN (1991) 
2. Lectures on QFT by Kevin Cahill
3. Explorations In Particle Theory
4. African Summer Theory Institute
5. TASI 2010 Videos especially the one given by Matthew Strassler about the Higgs sector in SM and fundamentals in Particle Physics.

I have many links to post, but I don't have time to update :)

Update: I have added the lectures given by de Witt, it is presented so long ago like 20 years ago at CERN, and just recently I had spare time to watch and go through the lectures. I must say that the details given in these lectures are really fascinating. To grasp those details from somewhere else is almost impossible (too much time consuming). Otherwise, you should read many textbooks and do a lot of problem-solving. I also checked his web page for notes, and I have also found many resources. The notes, indeed, have many details and you see a lot when you walk through this wild topic compared to other textbooks.

I wanted to update this blog since I created but somehow time passes, and I just can't do due to the absence of free time. You may find some interesting links on this FaceBook Group Page. I try to gather interesting kind of news in High Energy Physics.