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.
Monday, August 30, 2010
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!
George
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!
George
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 http://www.madscitech.org/ .
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 http://www.madscitech.org/ .
That is all for now, I will now check out how to include mathematical symbols in text.
George
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