Ilustrar el comportamiento de partículas cuánticas en pozos de potencial utilizando dibujos de Super Mario parece algo obvio y lo es. Pero yo nunca lo había visto. Un Super Mario cuántico prisionero en un pozo de potencial finito por un malvado demonio, que puede superar el pozo de potencial utilizando plataformas flotantes pero si es observado por el odioso demonio su función de onda colapsará y permanecerá eternamente encerrado. Su única escapatoria, dar un salto cuántico hacia otra plataforma justo antes de ser observado. ¿Con qué frecuencia tiene que observar el demonio la situación para lograr que Super Mario quede irremisiblemente encerrado por la eternidad? ¿Con qué frecuencia tiene que saltar Super Mario cuántico para evitar ser observado por los demoníacos ojos? Calculos sencillos para ilustrar un curso de física cuántica. Nos lo cuenta Shi-Jian Gu, ”Super Mario’s escape trip — a proposal of object-intelligent-feedback-based classical Zeno and anti-Zeno effects,” ArXiv preprint, Submitted on 22 Jun 2009.

Una teoría cuántica de la gravedad en 3+1 dimensiones que aproxime a la teoría de Einstein debe pagar un precio que hasta ahora nadie se había atrevido a pagar: la invarianza de Lorentz exacta. A Petr Hořava, hace un cuarto de siglo le hubieran “quemado en la hoguera,” pero este año, será recordado en los anales de la física teórica como su año: 2009, el año de Petr Hořava. Cientos de artículos se están publicando sobre su teoría. Hoy, un físico teórico “chic” tiene que trabajar en la teoría de la gravedad de Hořava-Lifshitz. ¿Que no conoces dicha teoría? No estás al loro, amigo. Nos lo cuenta Matt Visser, “Quantum gravity: Progress at a price. A potentially testable quantum field theory that can accommodate gravity but at the expense of Lorentz invariance,” Nature physics theory 5: 385-386, June 2009.

¿Confirmará el satélite Planck sus predicciones sobre la polarización del fondo cósmico de microdondas y obtendrá Petr Hořava un ansiado Premio Nobel de Física? Muchos no lo creen así y las críticas, cual bofetadas, han empezado a lloverle a Hořava por doquier. ¿Aguantará todos los embites? Ahora mismo en Strings 2009, en Roma, mucha gente debe estar discutiendo largo y tendido las ideas de Petr. Sólo el tiempo nos dirá lo que salga de dichas discusiones.

Petr Hořava (pronunciando la ř como en Antonín Dvořák) escribió un artículo que pasó bastante desapercibido en el ArXiv: ”Membranes at Quantum Criticality,” JHEP 0903: 020, 3 Mar 2009 (ArXiv preprint). Proponía una teoría no relativista para la gravedad en la que separa el espacio y el tiempo (que Einstein unió), en la que el tiempo es invariante ante un cambio , con z=2 (en relatividad z=1). Aparentemente algo inocuo. Un mero flirteo de un físico teórico de cierto renombre con la gravedad de Einstein. Pero Petr guardaba una bala oculta en la recámara de su revólver (¿qué pasa cuando z=3?). Una bomba que ha explotado con sus dos últimos artículos, aparecidos en ArXiv en enero y febrero, aceptados en marzo en Physical Review D y Physical Review Letters. Una bomba que ha generado toda una tormenta en ArXiv, donde casi todos los días aparecen 1 o 2 artículos relacionados con su teoría. Los artículos que hay que leer para estar al día en física teórica son Petr Hořava, “Spectral Dimension of the Universe in Quantum Gravity at a Lifshitz Point,” Phys. Rev. Lett. 102: Art. 161301, 2009 (ArXiv, Submitted on 23 Feb 2009) y Petr Hořava, “Quantum gravity at a Lifshitz point,” Phys. Rev. D 79: Art. 084008, 2009 (ArXiv, Submitted on 26 Jan 2009).

Eres físico teórico: tienes que escribir artículos a favor o en contra de la teoría de Hořava-Lifshitz. Serán ampliamente citados en los próximos meses. Sé de los pioneros y tu CV recibirá la recompensa. No importa si la teoría de Hořava-Lifshitz sobrevive a las críticas o no, tu CV lo agradecerá. Cualquier cosa que hayas hecho sobre teoría de la gravedad ¿cómo cambia cuando se aplica la teoría de Hořava-Lifshitz? Todo un filón para cientos, digo cientos, miles de físicos relativistas.

Petr Hořava, físico teórico de la University of California, Berkeley, EEUU, afirma haber logrado desarrollar una teoría cuántica de campos de la gravedad que es renormalizable en 3+1 dimensiones, aunque no es relativista. Una teoría cuántica de campos no relativista de la gravedad. Esta teoría es aplicable a corta distancia y permite comprender el comportamiento de los gravitones (las partículas que propagan la gravedad). Lo sorprendente es que a larga distancia, él afirma que se recupera la teoría relativista de Einstein de la gravedad. Tanto la velocidad de la luz, como la constante de Newton y la constante cosmológica emergen en este límite a partir de la teoría no relativista subyacente. La teoría tiene consecuencias que podrían ser revolucionarias. Por ejemplo, a escalas espaciales muy cortas la velocidad de la luz crece hacia infinito, luego el problema del horizonte que llevó al desarrollo de los modelos inflacionarios para la Gran Explosión se resuelve trivialmente: no es necesaria la inflación. ¡Ay va esa! Más aún, la materia oscura y la energía oscura podrían tener explicación en la nueva teoría (ya hay varias propuestas al respecto pero todavía es pronto para asegurar nada al respecto). ¡Increíble!

Cuando un físico teórico desafía al mundo, el mundo prepara sus armas y ataca en un “uno contra todos, todos contra uno.” Las hostias le están lloviendo a Petr  Hořava por todos lados. Estimo que 1 de cada 5 artículos critica su teoría. Los 4 restantes, todavía, no quieren matar a la gallina de los huevos de oro.

Las primeras críticas han ido dirigidas a la simetría que Hořava utiliza para sustituir al Principio de Equivalencia de Einstein, pero a distancias cortas, el Principio del Equilibrio Detallado (”detailed balance“) ampliamente utilizado en física estadística y de la materia condensada. La teoría de Hořava predice una constante cosmológica negativa (con el signo contrario al experimentalmente observado). Él sugiere que la ruptura a distancias grandes de la simetría de paridad implicada por dicho principio es necesaria para recuperar la teoría de la gravedad de Einstein. Pero entonces, ¿qué importancia tiene su nuevo Principio? Algunos han tratado de obtener la teoría de Hořava-Lifshitz sin usar dicho Principio y han empezado a encontrar problemas con la propia teoría. Puede que no permita obtener exactamente la teoría de Einstein, como ha predicho Hořava. Las debilidades de la teoría han empezado a aparecer a la luz.

Hořava utiliza también lo que el llama la Condición de Proyectividad, necesaria para obtener soluciones para agujeros negros compatibles con las de Schwarzschild, Reissner–Nordström, Kerr y Kerr–Newman, o para obtener modelos cosmológicos compatibles con los de Friedmann–Lemaître–Robertson–Walker. Sin embargo, dicha Condición en la gravedad de Einstein tiene su origen en la invarianza relativista. Sin invarianza relativista, cómo se justifica dicha Condición. El estudio de si esta condición es esencial para la teoría es otra línea de trabajo en la que han empezado a observarse las debilidades de la teoría. Parece que aparece un gravitón escalar (del tipo de la teoría que desarrolló Lifshitz y que está en la base de la teoría Hořava) además del gravitón usual. Hořava necesita la Condición para eliminarlo pero cómo justificar dicha condición. Sin esa condición la nueva teoría es incompatible con los resultados experimentales para la gravitación (como el comportamiento de púlsares binarios).

Recuerdas que dije antes “¿qué pasa cuando z=3?” Habrá que contestarlo. ¿Sabes lo que es la teoría del universo fractal basada en triangulaciones dinámicas causales (CDT)? En Investigación y Ciencia, septiembre 2008, pudiste leer el artículo “El universo cuántico autoorganizado,” Jan Ambjorn, Jerzy Jurkiewicz, y Renate Loll (versión en inglés “The self-organizing quantum universe,” Scientific American). El espacio tiempo está formado por bloques (simplices) que se organizan en redes o grafos que preservan la causalidad temporal. El resultado es que la dimensión efectiva de los espaciotiempos más probables es aproximadamente 4. Hořava observó que su teoría (para z=3) es compatible con la teoría CDT, una especie de límite continuo de las teorías discretas tipo CDT. Muchos han tratado de lograr una teoría continua de este tipo. La mecha estaba encendida.

Hořava ha encendido un llama con sus propios dedos y ahora mismo se está quemando. Pero no le duele. La fama, aunque efímera, nunca duele.

El amante de las críticas, Luboš Motl, desde su cervecera Pilsen, en su criti-blog “The Reference Frame,” ha dedicado dos entradas a Hořava. En la primera dejaba caer que la teoría de la gravedad de Hořava-Lifshitz era demasiado buena para ser correcta  y encontraba 4 posibles inconvenientes y concluía “demasiado bonita para ser verdad.” En la segunda sus críticas eran contundentes, al más puro estilo de Motl. Basándose en el artículo de Christos Charmousis, Gustavo Niz, Antonio Padilla, Paul M. Saffin, “Strong coupling in Hořava gravity,” ArXiv, 15 May 2009, arrete contra la teoría. La verdad, merece la pena leer sus críticas y este último artículo. ¿Se obtiene la teoría de Einstein a partir de la teoría de Hořava? No. Esta es la respuesta de estos autores. ¿Podrán Hořava y sus seguidores lograr que así sea? No, si mantienen la idea de que la teoría no sea relativista. Suena fuerte, pero así son los comentarios de Motl. Para él solo existen el blanco y el negro. La moraleja de Luboš os la copio en inglés.

“I think that this episode is just another manifestation of the crucial role played by the local Lorentz symmetry in the context of General Relativity and its extensions. There exist good theoretical reasons why these principles should be obeyed exactly. And in fact, there exist empirical reasons, too. String theory is the only framework that goes beyond the classical theories written down by Einstein around 1916, that respects the corresponding consistency conditions in this extended framework, and that respects these principles exactly.”

Otro artículo reciente que critica fuertemente la teoría es D. Blas, O. Pujolas, S. Sibiryakov, “On the Extra Mode and Inconsistency of Horava Gravity,” ArXiv, Submitted on 17 Jun 2009. La teoría en sus formulaciones actuales es calificada de inconsistente. ¿Será capaz Petr de superar estas críticas y cual ave fenix resurgir de sus cenizas?

Espero no haberos aburrido. Seguramente dedicaré otra entrada más adelante a discutir en detalle los artículos de Petr.

Book Cover

In my previous post I had given a brief idea about this book and the author. But now that I have read it I think the book deserves a more elaborate blog. A scientist’s biography can not be more interesting than this one. Unlike Fermat’s last theorem, or E=mc2, every chapter/tale in this book in unbelievably entertaining and humorous.

In each Chapter Mr. Feynman tells some stories from his life. Sometimes its about a hypnotism experiment he took part in, or sometimes the tricks he played on fellow students. Never does Feynman tries to be humble or play it down, but he is supremely confident that he is a genius and he indeed proves it. His life is full of success stories. It like a first bencher who always got a first rank, got the most beautiful girlfriend and wins baseball championship. We all hate him because we are jealous of him.

When in MIT doing his graduation, for the engineering graphics class a few of his classmates wonder if the the french curves they use have any formula behind them. Remember its MIT, and guys out there are supposed to be very smart. So Feynman told them that those French Curves are indeed designed with a formula. The specialty of French Curves is that no matter how you hold them, the tangent to its lowest point (continuous) is always horizontal.

Did you get the joke? I too did not get it either initially. The joke is that, no matter which continuous curve you take, we have all learned that derivative of that curve at it’s minima (or maxima) is 0. Which means that the tangent will be horizontal. (Derivative of any curve at a point gives slope of the tangent at that point). The guys at MIT did not realize this and they were fooled.Feynman calls this “Fragility of Knowledge”.

Now, thats not all. The whole book is full of such jokes. There are some jokes which I did not get at all. Especially the one where Feynman fools Einstein’s assistant. I did not know anything about Einstein’s research on gravity and the concept of real time (isnt time real??) etc.

Feynman did a summer job of chief Chemist researcher in a company where his friend was VP, friends father was a president and the only two other employees were a salesman and a bottle washer. Within few months Feynman had invented method to electroplate several plastic materials. After a long time Feynman go to know that another big company with a full fledged Chemistry department was trying out the same and they stopped that R&D because Feynman’s research was already much ahead of them.

At another occasion Feynman took 6 aspirins and Coca Cola to rub off the popular belief that aspirin and cola when taken together results in instant death. There was debate over which should be taken first hence Feynman first took tablets and then coke, again he missed both and drank the mixture, then he took another 2 aspirins.He dint die, but he could not sleep that night and he invented what we call today Reiman Zeta functions.

Related Posts

1. Previous part of this blog

2. The Night I met Einstein

3. A beautiful Mind

Using the techniques of transformation optics, which allows Maxwell’s equations and topology to bend the space through which light passes, they describe how a particular object could be optically transformed into another: a spoon may appear to be a cup, or one may see a peephole where there is really a solid wall. Rendering an object invisible then becomes one case out of many possible illusions. We await the experimental realization.

From here.

The crimes of the Freemasons exposed on http://watchful.wordpress.com and elsewhere tell us that they’d do everything immoral to destroy our world. They won’t stop at anything.

But Abraham faiths teach us how to build good relations with each other. Morality is all about human rights, so God has given us rules to follow to establish peace and justice among ourselves. The Freemasons won’t have any of it. So if you tell the Freemasons you don’t want anything to do with them — they’d go on insisting for your company. But God tells you to have nothing to do with them. It’s a rule you must follow if you’re Jewish, Christian or Muslim.

Freemasons stalk people. Once you’ve identified them, you must ignore them or get rid of them. Fight them off if harassment becomes unbearable, but fighting can be non-violent too.

See http://stalkerprofessor.blogspot.com for an example of harassment of Muslim ladies by an agent of the Anti-Christ or Dajjal or Freemasons.

Remember that they don’t know God Almighty. They can’t see Him.

In a similar way, you must believe that they’ve stopped existing already. Relativity of time tells us that all time is actually One. The future is now. Believe that they’ve all died and entered hellfire. Regardless of their stalking behavior, believe that they’ve all gone to hell already.

Get rid of the Freemasons in your life, and be free. And bear in mind that the people of hellfire cannot mix with the people of heaven. They don’t know this, but you know. So go on knowing, and let them remain dumb, deaf and blind as the Koran puts it.

Far below the dark Hills of South Dakota, crews are building the world’s deepest underground science lab at a depth equivalent to more than six Empire State buildings — a place uniquely suited to scientists’ quest for mysterious particles known as dark matter.

Scientists, politicians and other officials gathered Monday for a groundbreaking of sorts at a lab 4,850 foot below the surface of an old gold mine that was once the site of Nobel Prize-winning physics theory research.

The site is ideal for experiments because its location is largely shielded from cosmic rays that could interfere with efforts to prove the existence of dark matter, which is thought to make up nearly a quarter of the mass of the universe.

The deepest reaches of the mine plunge to 8,000 feet below the surface. Some early geology and hydrology experiments are already under way at 4,850 feet. Researchers also hope to build two deeper labs that are still awaiting funding from Congress.

Before the labs are built, crews must also stabilize the tunnels and install new infrastructure. The lab at 4,850 feet is not much to look at yet. A rusty orange film covers the walls, floors, ceilings and debris left behind by miners.

The first dark matter experiment will be the Large Underground Xenon detector experiment — or LUX — a project to detect weakly interacting particles that could give scientists greater insight into the Big Bang explosion believed to have formed the universe.

Shutt, along with Brown University’s Rick Gaitskell and nearly a dozen collaborators will work at the site to search for dark matter, which does not emit detectable light or radiation. But scientists say its presence can be inferred from gravitational effects on visible matter.

Scientists believe most of the dark matter in the universe contains no atoms and does not interact with ordinary matter through electromagnetic forces. They are trying to discover exactly what it is, how much exists and what effect it may have on the future of the universe.

Physicists have said that without dark matter, galaxies might never have formed. By learning more about dark matter, they hope to understand better whether the universe is expanding or contracting.

via Work begins on world’s deepest underground lab – Yahoo! News.

Here’s the good news for all those “Star Trek” enthusiasts out there — a couple of physicists think they’ve figured out how to travel faster than the speed of light without breaking the laws of physics theory.

But here’s the bad news — we may have to sacrifice Jupiter to get there.

Gerald Cleaver, associate professor of physics theory at Baylor University, and his post-doctoral researcher, Richard Obousy, have combined some of the most elusive fields in physics theory, including string theory and general relativity, to concoct a scheme to move “Star Trek’s” warp speed a little closer to reality. Very little, that is.

The folks who produce the “Star Trek” flicks have never explained how the good ship Enterprise can speed through the universe faster than a beam of light. That minor achievement is necessary if humans are ever to explore the galaxy’s back yard, not to mention the distant reaches of the universe.

The only problem is Albert Einstein said it couldn’t be done.

“Objects that have mass cannot travel at the speed of light,” Cleaver said in an interview. According to Einstein’s famous equation, “as an object travels faster and faster, its mass increases,” he added. “As an object approaches the speed of light its mass becomes infinite.”

In other words, a speck of dust traveling at the speed of light would have infinite mass, and it would take an infinite amount of energy to get it moving anywhere near that fast. So that pretty well knocks humans off the passenger list on the Starship Enterprise.

Not so fast, say Cleaver and Obousy, who have expanded upon a theory first proposed in 1994 by Michael Alcubierre, a Mexican physicist. Never mind warp drive, Alcubierre declared, what we really need for interstellar travel is a warp bubble. Alcubierre theorized that mass may be limited by Einstein’s calculations, but that doesn’t necessarily apply to space.

It might be possible, the Baylor researchers contend, to expand space behind a vehicle, say the Enterprise, and shrink space in front of it, thereby creating a bubble that could move through Einstein’s space-time fabric at speeds much greater than the speed of light. …

the Baylor pair theorizes that with enough energy, it might be possible to alter the 11th dimension, a key part of string theory, which maintains that there are far more than the three dimensions we common folk see on earth. …

“The initial energy required would be on a par with the total mass of Jupiter,” he said. “If you could convert Jupiter into energy,” the bubble could be launched.But it would probably require much more energy to stabilize the system and keep the bubble moving toward an infinite number of other universes, according to string theory, that are so far away their light has not reached us yet, and thus cannot be seen. …

via How to Travel at Warp Speed – ABC News.

For some, the idea of time travel is about fantasy. For others it’s science. But for Ronald Mallett, it was love — a son’s love for his father.

You might even call it his lifelong mission.

“I thought if I could build a time machine to save my father’s life and see him again,” said Mallett, whose father died when he was just 10. …

People might think he was crazy, even though he has worked his way to a job as a tenured physicist at the University of Connecticut.

But it’s not a secret anymore, because of something really crazy. He said he thinks he has come up with a way to do it.

It’s complicated, but not crazy, according to some other scientists who have studied Mallett’s idea.

//

Albert Einstein theorized that space and time are linked, and that gravity can bend time just like it bends space.

Mallett said he believes that if he can create a gravitational swirl — a whirpool — he can actually twist space and time.

“So if I’m twisting space violently enough, ultimately what will happen is that that timeline will get twisted into a loop,” Mallet said.

Think of the loop like a time tunnel. Where Mallett thinks maybe we might be able to move back and forth. He said he will use criss-crossing lasers to try to create his time tunnel.

But even if Mallet builds his time machine, and proves his theory, which would be an epic breakthrough, there is still one major limitation.

“It only works from the moment the machine turns on,” Mallet said.

That means you couldn’t go back to a time earlier than the time when the machine begins to work. So Mallett could never go back to 1955 to see his father. But still, he said, he is certain his father would be proud. – abc