Monday, August 30, 2010

Creeping Featuritis

In the computer world there is a term used to describe a project, intended to be accomplished in finite time, where the client keeps wanting new things added before the project is completed; called creeping-featureitis. When building a computer project, this is a bad thing.

In theoretical physics, since we know we do not know all of the rules of the game, this is the norm. We are always adding new things: ideas, theorems, examples, counterexamples, contradictions, etc.

It is not surprising that theorists have computer code that is ever expanding; that is how we think!

To that extent, all theorists engage in creeping-featuritis and it is the way it should be.

Wednesday, August 25, 2010

Weird Fractional Quantum Hall Effect

In a recent publication to Physical Review Letters, "Optical Probing of the Spin Polarization of the v= 5/2 Quantum Hall State" the authors: M. Stern, P. Plochocka, V. Umansky, D. K. Maude, M. Potemski, and I. Bar-Joseph, describe a phenomena resulting in a pseudoparticle having non-integer charge!

This is all based on the fractional quantum Hall effect.

Recall the classical Hall effect, discovered by Edwin Hall in 1879. This effect occurs when you apply a magnetic field perpendicular to a current in a conductor, producing a voltage difference across the conductor. This voltage difference is sometimes called the Hall Voltage.

If you have a system of electrons in a plane (two-dimensional) or on a surface that are at low temperatures, you can produce Hall voltages of only quantized values by applying a strong magnetic field. This is the integer quantum Hall effect. You can calculate the Hall Resistance,

R= (h/e^2)/v

Where h is Planck's constant, e is the fundamental charge, and v is called the filling factor.

In some cases the electrons behave as if they are a fluid. In this case they behave as a pseudoparticle with fractional charge. Very interesting! This occurs when v is fractional, it is specifically interesting at v = 5/2.

I have not yet finished the letter, but something mysterious occurs at v = 5/2. There is a lot of interesting physics here!


Friday, August 20, 2010

Hellow World

Hello everyone! My name is George, and I used to write a column on The Citizen Scientist (an e-publication put out by the Society for Amateur Scientists) called The Mind of a Theorist. This publication has ended (along with my column), at least temporarily, so I have relaunched it here.

The goal of the column was to provide good content about theoretical physics in an educational way.

I was forced to change the format due to editorial interference.

I want to return to the old way of doing it.

To that end, I will be going over my old columns and resurrecting them for the dead here. In some cases I will not change much, while in some I will trash the old and ring in the new right away.

With each post I will discuss a physics news item, my research, a topic of interest to readers, a comment from a post, or other such. I will also present something educational; something to help you become a theoretical physicist - even an amateur one; and then once a week I will issue a theorist challenge. At the moment, I will not be able to provide any prizes, but if I get enough support that might happen. I will always answer the challenge in the next week.

About me: I am the President of the nonprofit organization Madison Area Science and Technology (MAST). We do science without regard to credentials. You can check out our web site at .

That is all for now, I will now check out how to include mathematical symbols in text.