# Author Archives

I am an experimental particle physicist, traveler, teacher, researcher, scientist and communicator of ideas.

I am a quarkist and a bit quirky ! Hypothesis non fingo, eppur si muove, dubito cogito ergo sum are things that turn me on !

Researcher in experimental high energy physics (aka elementary particle physics; like “quarks, leptons & mesons and baryons”) … Teacher of Physics (and occasionally chemistry and maths) Blogger (check my website; mdashf.org) !

Love to read read and read but only stuff that interest me. Love to puff away my time in frivolities, just dreaming and may be thinking.

Right now desperately trying to streamline myself.

• #### Maxwell’s equations

Electromagnetic theory, Lecture — I.

Maxwell’s equations

This lecture, the web version of the first lecture given in the electromagnetic theory paper of the physics honors degree class, was delivered on 21st December 2017. All electromagnetic theory lectures of this series, will be found here.

Also read part-2 of the linked lecture. That describes the subject matter of this lecture, in a good deal of depth.

Topics covered

A. Maxwell’s equations — basic form

B. Displacement current — Correction to Ampere’s law

C. Maxwell’s equations — in material media

Maxwell’s equations

Maxwell’s equations the basic forms

The Maxwell’s equations without the corrections to the Ampere’s law can be written as the following;

Electrostatics is when the electric charge and electric current densities, that produce these field, known therefore also, as the sources of the field, do not explicitly depend on time, that is, are constants. These sources or distributions depict the behavior of the field, and their independence from time means the fields do not vary in time, but vary only under spatial transformation.

Note that we are not talking about sources in the Maxwell’s equations above, but the ones that actually produce the E and B fields of the equations. The sources present in the equations above would alter these static fields though.

Accordingly the Maxwell equations would change their behavior in dynamic — i.e. time varying conditions, than they exhibit in the static conditions.

Equation (ii) has no names, but sometimes given a name, Gauss law — of magneto-statics.

Equation (iii) is known as Faraday’s law — of electromagnetic induction.

Equation (iv) is known as Ampere’s law.

Inconsistency in Maxwell’s equation
The Maxwell’s equations in this form are not the most general form of the eponymous set of equations. Also they are fraught with some degree of inconsistency.

Lets gaze deeper.

• #### Microcanonical ensemble

Microcanonical ensemble
Lecture IV; This lecture, the 4th in the series of statistical mechanics lectures, a paper for the physics honors degree class, was delivered on the 10th of January this year (2018).

You can find the previous lectures here ( Lecture — I, II ) and here ( Lecture — III ).

Topics covered in this lecture

a. Recapitulation of some previous ideas and  — important remarks

b. Microcanonical ensemble — definition and properties

c. Some basic parameters and formalism

Recapitulation and remarks
In our previous lecture we defined the phase space density or distribution function rho (q, p; t) for a classical statistical system with an aim to connect it to a thermodynamic system.

We saw that an ensemble system would be stationary if rho does not have any explicit time dependence, …

Remarks
The type of general ensemble we defined as mental copies of actual system occupying each possible microstate can be called a Gibbsian Ensemble.
The above condition of statistical density as a stationary or time-independent variable would represent conditions of equilibrium.
We defined ensemble average of a physically measurable quantity

• #### Phase space, ensemble and Liouville’s theorem

Phase space, Ensemble and Liouville’s theorem.

Topics covered in this lecture

a. Ensemble and average — thermodynamic systems

b. Phase space — a classical system

c. Liouville’s theorem

Ensemble and average in thermodynamic systems

For a given “macrostate” (N, V, E) a statistical system, at any instant of time, t, is likely to be found in any one of an extremely large number of distinct “microstates”.

When time passes, the system evolves into different microstates. In due course of time the system exhibits an average behavior of all microstates it passes through.

We can equivalently depict this behavior by envisaging a large number of mental copies of the system, with the same macrostate as the original system, but all the possible microstates, in which the system can exist, all at once. Such a collection of hypothetical or mental copies of the given system is known as an ensemble.

Thus the average behavior of the ensemble is expected to be identical with the time-averaged behavior of the actual physical system. In fact this is one of the fundamental requirements for statistical mechanics to be valid. No matter which mathematical avenue we prefer to meander through we must in the end reach our unique destination of physical validity.

To understand the deeper aspects of this ensemble theory we need to define what is known as “phase space” of a statistical system.

• #### Aerial view of Bhabanipatana

The video shows a beautiful video of the city of Bhabanipatana — alternated to  Bhawanipatna due to influence of Hindi, in the district of Kalahandi of the state of Odisha. The name Kalahandi might invoke a stark sense of depravity as it brings to memory the notoriety of poverty associated with the KBK districts and the perpetual image of the state itself as a residence of the poorest of poor. But reality is as startlingly contrasting as this video shows.

• #### The plight of Paralakhemundi

Once the citadel of the mighty Gajapati, who ruled from the Ganga to the Godavari: Paralakhemundi of the Gajapati district, languishes in the peril of apathy from the system, read mostly, the Indian Railways here.

26 years is a long time in democratic memory and forcing our own citizen to live in the darkness like paupers is nothing less than sort of a genocidal crime.