Welcome Guest!

# kapoor's blog

For page specific messages
For page specific messages

## Problem/QM-07010

A physical system has dynamical variables $X,Y,Z$ represented by the  $2\times2$ Pauli matrices $\sigma_x,\sigma_y,\sigma_z$.

Compute the average $$\langle f|Y|f \rangle$$  and the uncertainty $\Delta Y$ for the variable $Y$ if the state is given to be     $$f = \begin{pmatrix}1+3i \\3-i \end{pmatrix}$$  What does the value  for $\Delta Y$ suggest? Give your remarks, if any.

## What is a gauge? A lively discussion by experts on Face-book

##### Sudhir Raniwala
Yesterday at 10:16 ·

 A student asked a question that I do not have an answer to, and need an answer that satisfies me.

## It is never too late to learn: Green A short biography

Green function are imprtotant tools part of every physicists arsenal. They appear every where fron electrodynamics to optics and fluid dynamics andto quantum field theory. Here is an extract  briefly describing his times. He entered Cambridge as graduate student at the age of 40.

## How to Create Problems for Students (Part-I)

In this blog I share my sceme of creating problems and assessment for teaching and evaluation.

## The Proofs Programme has only a beginning

In a particle physics text book "Elementary Particles and Their Currents" written in 1968, the author, Jermey Bernstein concludes the book by
writing

## History of Matrix Mechanics and Heisenberg's Contributions to Quantum Mechanics

"Birth of Quantum Mechanics" by Jagdish Mehra

A delightful lecture by Jagdish Mehra, later published as CERN Report in 1976, gives blow by blow account of how Heisenberg's ideas developed and what his contemporaries thought about his works.  This report is being made available to everyone as an attachement here.

REFERENCE

Jagdish Mehra, "Birth of Quantum Mechanics ", Heisenberg Memorial Lecture ( March 30, 1976), Published as   CERN Report 76-10

## Uncertainty Principle : An Application Straight from Landau Lifshitz

In this blog I take you to an original argument in the book, by Landau Lifshitz's on Qunatum Mechanics, about using uncertainty principle to determine if the number of bound states  for a potential will  be finite or infinite.

## Proposed Physics Content on 0space (Part-I ): Important features.

When did you first come across a serial some where? You may or may not remember, but I do.

## For my SF volunteers.

Dear student friends,

I have earlier contacted you regarding your plan during winter vacations. Many of you have been

asking about the work to be done. If you can spare time and energy, please create an account and