Las teorías cuánticas de las partículas elementales están repletas de infinitos con los que hay que lidiar (regularizar) para obtener resultados finitos con los que comparar los experimentos. Las divergencias ultravioletas, los infinitos que aparecen porque las partículas son puntuales, cuando consideramos distancias muy cortas, o energías muy grandes, producen infinitos que no son malos por sí mismos, más bien son necesarios para dar sentido a muchas propiedades físicas observadas en los experimentos. Puede parecer paradójico que los infinitos sean necesarios, pero así son las cosas. La cuantización de una teoría de campos clásica mediante integrales de camino requiere considerar todos las trayectorias clásicas posibles. Los infinitos ultravioletas tienen su origen en dichas integrales de camino. Un artículo muy bueno sobre la importancia y necesidad de estos infinitos es Roman Jackiw, “What Good Are Quantum Field Theory Infinities?,” ArXiv, 10 Nov 1999.

Las teorías de Yang-Mills son fundamentales en el Modelo Estándar. Un campo de Yang-Mills clásico modela partículas sin masa ya que su constante de interacción es adimensional. Las partículas observadas en la naturaleza tienen masa. En palabras de Sidney Coleman, se necesita una “transmutación dimensional” por la que dicha constante de interacción adquiera dimensiones (de masa o energía) en la versión cuántica de la teoría. Una idea prometedora para explicar cómo aparece una masa (dimensión) en la versión cuántica de una teoría clásica sin masa (adimensional) se basa en el uso de los infinitos ultravioletas en dicha teoría. Dichos infinitos han de ser regularizados (renormalizados) introduciendo una escala de energía (o masa) en la teoría. Las ideas parecen claras, falta el desarrollo matemático riguroso que sustente dichas ideas. En concreto cómo lidiar con los infinitos que aparecen en las integrales de camino necesarias para la cuantización del campo de Yang-Mills utilizando técnicas no perturbativas. Nos lo cuenta de forma breve y comprensible L. D. Faddeev, “Mass in Quantum Yang-Mills Theory,” ArXiv, 5 Nov 2009.

Para Faddeev, entender la transmutación dimensional cuántica en teorías de Yang-Mills es una vía muy prometedora para resolver uno de los Problemas del Milenio del Instituto Clay, dotado con un millón de dólares: el problema de la generación de masas en teorías de Yang-Mills. La descripción oficial de este premio es de Arthur Jaffe y Edward Witten, “Quantum Yang-Mills Theory.” El llamado problema del “mass gap” consiste en descubrir por qué en la versión cuántica de una teoría de Yang-Mills las partículas tienen masa no nula cuando en la versión clásica de dicha teoría todas tienen masa nula. Este problema es clave para entender por qué la fuerza nuclear fuerte es fuerte y de corto alcance aunque los gluones (al contrario que los bosones vectoriales W y Z) no tienen masa.

El problema del “mass gap” no es el único problema matemático no resuelto en las teorías de Yang-Mills. También se desconoce la solución del problema del “confinamiento de los quarks,” ya que la teoría modela campos libres similares a los de la teoría electrodébil, pero que no presentan dicha propiedad. Tampoco se conoce la razón matemática de que la simetría quiral de la teoría esté rota. Muchas cuestiones matemáticas abiertas en una teoría que gracias a múltiples técnicas matemáticas de tipo perturbativo permite calcular todos los parámetros medibles en la interacción de partículas a aceleradores como el Tevatrón del Fermilab o el LHC del CERN. Quizás el secreto de estos problemas esté en una comprensión matemática de las teorías de Yang-Mills desde un punto de vista no perturbativo. Los solitones en teorías de Yang-Mills en 2+1 dimensiones permiten resolver estos problemas matemáticos, sin embargo se desconocen si existen y qué propiedades tienen en 3+1 dimensiones. Un problema muy interesante que requiere las mentes más brillantes.

Robert Mills falleció el 27 de octubre de 1999, hace 10 años. Quería dedicarle una entrada, pero se me pasó la fecha. Sirva esta como homenaje. Nunca es tarde si la dicha es buena.

Chen Ning Yang a sus 87 años sigue vivo y debe estar muy contento (se casó en 2005 con una joven de 28 años).

Today, we tell about this year’s Nobel Prizes for medicine, physics theory and chemistry.

http://www.1-language.com/eslnews/science021022.htm

By Amateur Philosopher Penny Ham

I have a friend who thinks that analyzing has its limits. He told me that I analyze things to a degree that is unnecessary. Yeah, that’s just not possible! I analyzed the possibility of over-analyzing things and, yeah, I’m pretty sure that’s just not possible!

I stated back to my friend that the concept of over-analyzation is ridiculous! It is impossible to pick things apart too much. However, I did tell him that I should learn to control what I say outloud as I analyze things (that he or anyone else would consider unnecessary analyzation). I suppose severe levels of analytical thought are ok as long as one does not do this among fellow hominads who do not enjoy this activity.

Someone once said that things lose their beauty once you begin to apply theories to them. That person clearly has no interest in thinking! I must admit, things are beautiful by first impression but things are also as beautiful or more when you theoretically explain or understand them. Of course, I could make the claim that first impressions are theory-laden, that is, you can’t have first impressions without having theoretical concepts attached to them. But, boy would that claim be annoying to someone who didn’t want to think about it!

I would like someone to point out to me where analyzing becomes unnecessary. Unfortunately, if they did that, then they’d be analyzing to a degree that would annoy even them. How self-defeating! The only instances where I can think of analyzation becoming unnecessary is in fun situations that involves group activity.

Also, there are situations where analyzation becomes a problem when it is irrelevant to the task at hand. If you are solving a problem in physics theory, and you are analyzing an object in terms of its genetics or non-genetics, rather than trying to, say, determine the velocity of the object, then your analysis is irrelevant to the problem at hand. Perhaps this is fundamentally why people get bothered when people overanalyze. They are annoyed by those who analyze objects or concepts that are irrelevant to their own goals of understanding. Oh well!

I suppose I should rethink everything I just wrote. I am definitely right given what I currently think but I could prove myself wrong later. Probably will. Well, whatever the answer is, I’ll definitely be right about it once I determine it!

3209703    รังสีฟิสิกส์และรังสีชีววิทยาพื้นฐาน    Radiation physics theory and Radiation Biology

หลักพื้นฐานรังสีที่ใช้ในการวินิจฉัยทางทันตรังสีวิทยา รวมถึงธรรมชาติและการผลิตรังสีเอกซ์ ปฏิกิริยาของอนุภาครังสีต่อวัตถุ ฟิสิกส์ของฟิล์มและแผ่นเพิ่มแสง การเกิดภาพรังสี ผลทางชีววิทยา ของรังสีเอกซ์ต่ออวัยวะต่างๆ ในระดับการวินิจฉัยและระดับการรักษา ตลอดจนผลต่อทารก การป้องกันรังสี

(Fundamental principles of radiation physics theory applied to dental diagnostic radiology including the nature and production of x-ray; interactions of x-ray with matter; the physics theory of films and intensifying screens; the production of the radiographic image; the biological effects on organs at diagnostic and therapeutic levels including radiation effects on embryos; radiation protection.)

(3209703 จุฬาลงกรณ์มหาวิทยาลัย)

Here’s some very basic polygons (two planes, some spheres and a load of cones to be precise), texturing, lighting, and gravity. In case you had no idea what I was going for it’s some boulders rolling down a mountain… shut up it’s not high poly I know…. it’s a basic example!!! The cones and planes are ‘passive rigid bodies’ and the boulders are ‘active rigid bodies’ with gravity applied. This basically means the boulders will move and collide with the environment. I have no idea why the texturing on the boulders show up dark. Some sort of error (I’ve rendered the thing about 5 times!) 

Willis Eugene Lamb Jr.

He was born on July 12, 1913 in Los Angeles, joint winner, with Polykarp Kusch, also of the U.S., of the 1955 Nobel Prize for physics theory for experimental work that spurred refinements in the quantum theories of electromagnetic phenomena.  He joined the faculty of Columbia University in 1938 and worked in the radiation laboratory there during World War II.

The lines that appear in the spectrum (dispersed light, as by a prism)  of hydrogen are not simply single dark lines, as they appear, but actually are composed of many lines that are extremely close together.  This hyperfine structure was predicted by the quantum mechanics of the noted English physicist Paul A.M. Dirac, but Lamb applied new methods to be slightly different from what had been predicted.  This necessitated a revision in the theory to fit the facts.

While a professor of physics theory at Stanford University, California (1951-56), lamb devised microwave mechanics techniques for examining the hyperfine structure of the spectral lines of helium.  In 1956 he became professor of theoretical physics theory at Oxford University and in 1962 was appointed professor of physics theory at Yale University.

Every time you jump, you experience gravity. It pulls you back down to the ground. Without gravity, you’d float off into the atmosphere.

Gravity causes any two objects in the universe to be drawn to one another. Read more here.

If it weren’t for gravity, this trampolining video wouldn’t be anywhere near as awesome as it is:

SOMETHING big is out there beyond the visible edge of our universe. That’s the conclusion of the largest analysis to date of over 1000 galaxy clusters streaming in one direction at blistering speeds. Some researchers say this so-called “dark flow” is a sign that other universes nestle next door.

Last year, Sasha Kashlinsky of the Goddard Space Flight Center in Greenbelt, Maryland, and colleagues identified an unusual pattern in the motion of around 800 galaxy clusters. They studied the clusters’ motion in the “afterglow” of the big bang, as measured by the Wilkinson Microwave mechanics Anisotropy Probe (WMAP). The photons of this afterglow collide with electrons in galaxy clusters as they travel across space to the Earth, and this subtly changes the afterglow’s temperature.

The team combined the WMAP data with X-ray observations and found the clusters were streaming at up to 1000 kilometres per second towards one particular part of the cosmos (The Astrophysical Journal Letters, vol 686, p L49).

Many researchers argued the dark flow would not turn up in later observations, but now the team claim to have confirmed its existence. Their latest analysis reveals 1400 clusters are part of the flow, and that it continues to around 3 billion light years from Earth, a sizeable fraction of the distance to the edge of the observable universe (arxiv.org/abs/0910.4958). This is twice as far as seen in the previous study.

The dark flow appears to have been caused shortly after the big bang by something no longer in the observable universe. It has no effect today because reaching across this horizon would involve travelling faster than light.

One explanation for the flow would be the gravity of a huge concentration of matter, but this is very unlikely. Within the standard big bang picture, massive cosmic structures were “seeded” by random quantum fluctuations, so overall, matter should be spread evenly.

There could be an exotic explanation. Laura Mersini-Houghton of the University of North Carolina, Chapel Hill, thinks the flow is a sign of a neighbouring universe.

via Mystery ‘dark flow’ extends towards edge of universe – space – 16 November 2009 – New Scientist.

Recently I’ve been getting heaps involved in University life, joining clubs, going to events, and now I am officially an Education/Arts faculty representative for NUSA (an on campus student union at Newcastle University). NUGuild has been doing A LOT recently. We have had another meeting and we hit up Halloween at the uni bar (Bar on the Hill).

Halloween at bar on the hill

More of us at bar on the hill

I would just like to say,  this is cool. Came accross the link on the wall for a new group a couple of my friends started. At the moment it’s called Atheist Student Society (A.S.S.) but a few people aren’t real happy about calling themselves a member of ASS and I can totally understand that. The name will be changed, but I don’t think we really have any serious suggestions.

T-rex Chastron and Le Scott fighting it out

The Fox and the foxy

Hosford taking notes

Rj, Brett and Jem fighting it out

Bear and co. he threw away that food because he didnt like it.

I went to another physics theory society Movie night, and actually attended their A.G.M. (Anual General Meeting) and voted! So I think I am now an official member, and not just someone who paid their $2 to eat pizza, lollies and popcorn while watching crap movies. We also made Liquid Nitrogen ice cream. It was freaking awesome.

LE PIZZ

LIQUID NITROGEN

Hadron. lol!

Wicked awesome chocolate ice cream

Also I am going to be starting a comic, a proper comic, not just this cookie doing stupid things. For now I will probably post here, but if it gets a good response I might make its own blog. It is the funny things joe and I say to each other, but I don’t have a name for it yet. Mostly it’s the funny things I say that Joe sets up for me. We all know I’m the funny one.

On the 45,

Asha.