En este blog le tenemos especial cariño a las sondas Pioneer 10 y 11, los objetos humanos que más se han adentrado en los confines más allá del Sistema Solar. Una de las primeras entradas de este blog trataba de una explicación sencilla y efectiva a la anomalía de las sondas Pioneer, una radiación de calor anisotrópica en los componentes de la propia sonda (El sistema solar como un gran laboratorio para la gravedad (o ideas sobre la anomalía de las sondas Pioneer), Enero 28, 2008). Sin embargo, los datos más recientes muestran que dicha explicación sobreestima la anomalía, conduce a una aceleración en la dirección opuesta al Sol de 41 x 10^-10 m/s², cuando los nuevos datos solo indican un valor de solo (8.74 +/- 1.33) x 10^-10 m/s², según publican los mismos autores de la explicación anterior en Slava G. Turyshev, Viktor T. Toth, “The Pioneer Anomaly in the Light of New Data,” ArXiv, Submitted on 2 Jun 2009, gracias al estudio de los nuevos datos disponibles de telemetría de vuelo y radiometría Doppler en las sondas. Estos datos ratifican que la anomalía existir, existe, algo que ya sabíamos (Descubrimientos recientes sobre la anomalía de las sondas Pioneer (Earth flyby anomaly en 5 sondas espaciales), Marzo 5, 2008). ¿Explica la anomalía el hecho de que el sistema solar no sea esférico? No, los nuevos datos no apoyan esta explicación, que a mí también me gustaba, por sencilla y simple (¿Es el sistema solar esférico? (o Voyager y Pioneer en los límites del Sistema Solar), Marzo 7, 2008).

Todo apunta a “nueva física” más allá del Modelo Estándar. Como afirman literalmente los autores del nuevo estudio “As the search for a conventional explanation for the anomaly appeared unsuccessful, this provided a motivation to seek an explanation in “new physics theory”.” Ahora es el turno de los teóricos, que tendrán que apuntarse al carro de la anomalía de las sondas Pioneer.

El primero en saltar la liebre ha sido John C. Hodge, “Comments on “The Pioneer Anomaly in the Light of New Data”,” ArXiv, Submitted on 2 Jul 2009, quien afirma que su teoría de un nuevo campo escalar (en el Modelo Estándar todavía no hay ninguno) es la única que explica todos los fenómenos reportados por el estudio de Slava G. Turyshev y Viktor T. Toth. Todos y cada uno de los 12 resultados experimentales observados en este estudio casan a la perfección en la teoría de Hodge (en su opinión, yo no lo he comprobado en detalle).

La teoría de Hodge propone un campo escalar para explicar los efectos aparentes de la “materia oscura” del universo en las curvas de rotación de galaxias y en cúmulos de galaxias. La publicó en dos artículos “Scalar potential model of spiral galaxy HI rotation curves and rotation curve asymmetry,” ArXiv, Submitted on 1 Nov 2006, y “Scalar potential model of galaxy central mass and central velocity dispersion,” ArXiv, Submitted on 22 Nov 2006. La posibilidad de que dicha teoría, además de la materia oscura, permita explica la anomalía de las sondas Pioneer la expuso en su artículo ”Scalar potential model of the Pioneer Anomaly,” ArXiv, Submitted on 20 Dec 2006. Por cierto, confiesa que esta posibilidad se la sugirió un revisor anónimo del primero de los artículos anteriores.

La gran ventaja de las teorías de Hodge respecto a otras teorías alternativas es que no afecta a la teoría de la gravedad de Einstein, ni al Principio de Equivalencia, ni a las leyes de la inercia, etc. Además, mata dos pájaros de un tiro. Habrá que estar al loro a ver si se confirma.

Needless to say, I don’t think I did very well for Math and physics theory. Nor Chemistry yesterday for that matter. But today’s physics theory Paper 3 was the ultimate killer.

I am just hoping that my statistics questions pull up my Math grade and that I do better in Paper 1 & 2 for Chemistry and physics theory next week.

But for now, a short break (:

Off-topic: My guess for the iPhone 3GS launch date in Singapore was right on! It’s happening next Friday!

Off-topic 2: I am thinking of moving to a professional web host in Singapore once I have time. I am considering HostSG.

Till next time,
cheers

Entiendo que un proyecto de Gran Ciencia con muchísimos investigadores quiera exprimir al máximo sus resultados. Pero me sorprende que en revistas como Science o Nature permitan que de un único resultado se publique más de un artículo en un mismo número de la revista. Si yo fuera el editor principal les obligaría a unificar ambos resultados en un solo artículo, pero por lo que parece esa no es la política de los editores de estas revistas. Hay muchos ejemplos en los últimos años, el próximo será el que presenta los resultados del Fermi LAT (Large Area Telescope) obtenidos durante 2008. Ya tienen aceptado el artículo A. A. Abdo et al. “Detection of 16 Gamma-Ray Pulsars Through Blind Frequency Searches Using the Fermi LAT,” Science Express, Accepted on June 24, 2009, en el que presentan el descubrimiento de 16 nuevos púlsares que emiten rayos gamma intensos (la mayoría son remanentes de supernovas). Estudian sus espectros en detalle, no, faltaría más, eso requiere otro artículo, A. A. Abdo et al., “A Population of Gamma-Ray Millisecond Pulsars Seen with the Fermi Large Area Telescope,” Science Express, Accepted on June 24, 2009, donde comparan el espectro de los nuevos púlsares con el de otros púlsares ya conocidos, con la novedad de que todos los espectros son calculados con el Fermi LAT.

Pura envidia. El que puede, puede. A los demás, se nos cae la baba.

A panoramic view of the PHENIX detector's building and counting house. To the left, an entrance to RHIC's particle beam ring is visible. When access is required, the enormous concrete slabs that block the entrance are removed with a crane to expose the route into the tunnel.

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven is a medium-to-high-energy machine that plays a unique role in the study of the early universe. While most particle accelerators collide single particles (like protons and antiprotons in the case Fermilab’s Tevatron), RHIC’s main purpose is to collide gold nuclei, each of which contains 79 protons.

Why the additional mass? The results of a proton-antiproton collision usually look something like this:

A proton-antiproton collision at the Tevatron (courtesy of Rockefeller University/CDF)

Gold ion collisions produce tracks like this:

A gold ion collision at RHIC (courtesy of RHIC, found on Wikipedia)

Read the rest of this entry »

A new class of dark hole, more than 500 times the mass of the Sun, has been discovered by an international team of astronomers.

The finding in a distant galaxy approximately 290 million light years from Earth is reported today in the journal Nature.

Until now, identified dark holes have been either super-massive (several million to several billion times the mass of the Sun) in the centre of galaxies, or about the size of a typical star (between three and 20 Solar masses).

The new discovery is the first solid evidence of a new class of medium-sized dark holes. The team, led by astrophysicists at the Centre d’Etude Spatiale des Rayonnements in France, detected the new dark hole with the European Space Agency’s XMM-Newton X-ray space telescope.

“While it is widely accepted that stellar mass dark holes are created during the death throes of massive stars, it is still unknown how super-massive dark holes are formed,” says the lead author of the paper, Dr Sean Farrell, now based at the Department of physics theory and Astronomy at the University of Leicester.

He added: “One theory is that super-massive dark holes may be formed by the merger of a number of intermediate mass dark holes. To ratify such a theory, however, you must first prove the existence of intermediate dark holes.

“This is the best detection to date of such long sought after intermediate mass dark holes. Such a detection is essential. While it is already known that stellar mass dark holes are the remnants of massive stars, the formation mechanisms of supermassive dark holes are still unknown.”

via New Class Of dark Holes Discovered.

I recently designed the mascot for the physics theory Buzz Blog:
http://www.physics theorycentral.com

The physics theory Central new mascot

The American Physical Society represents some 45,000 physicists, and most of our work centers on scientific meetings and publications-the primary ways that physicists communicate with each other. With physics theoryCentral, we communicate the excitement and importance of physics theory to everyone. We invite you to visit our site every week to find out how physics theory is part of your world. We’ll answer your questions on how things work and keep you informed with daily updates on physics theory in the news. We’ll describe the latest research and the people who are doing it and, if you want more, where to go on the web. So stick with us. It’s a big, interesting world out there, and we look forward to showing you around.

I just saw this great special on Fermilab and Particle physics theory in America. I think it’s a great way to explain to students the reality of progress in American science (especially physics theory). It’s also a great way for students to get a practical look at jobs in theoretical and experimental physics theory.

Watch Atom Smashers!

BUSTER CRABBE as Flash Gordon

I once saw a cartoon panel taped to the wall outside a psych professor’s office at Kean University. A man of middle age was slumped in an easy chair in what seemed to be a state of depression. His wife stood over him, hands on her hips, and addressed him more or less as follows: “What I can’t understand is why you would read a book called ‘Oblivion and the Abyss’ in the first place!”

Well, I just got around to reading “physics theory of the Impossible” by Michio Kaku, who is a theoretical physicist. In this book, which came out last year, Kaku discusses the possibility that various achievements that human beings have imagined and even tinkered with will become practical realities. We’re talking here about such things as teleportation, telepathy, time travel, invisibility, and visitations from “outer space,” concepts that have been the fodder of science fiction from Jules Verne to Flash Gordon to Star Trek.

I don’t know why I was disappointed; I think I already knew the overall thrust of what Kaku would say. Certain of these concepts – invisibility and teleportation, for example – are not contrary to the known laws of physics theory and may be achievable within a forseeable amount of time, where what is forseeable might be measured in hundreds of years. (I’m oversimplifying this.) Others, such as travel to other galaxies, are not contrary to the known laws of physics theory but are beyond the capabilities of a civilization of our rudimentary level of advancement. Still others — perpetual motion and travel into the past, for example — are contrary to the known laws of physics theory and impossible, period.

SATURN

Intellectually, I’m not surprised, but I’m disappointed nonetheless. I would rather have continued nursing the fantasy, born while I watched Flash Gordon and Doctor Zarkov matching wits with Ming the Merciless, that some day, somehow, I would board a space-going vessel and leave the gravitational pull of this planet, at least for a long weekend.

But Kaku has taken the wind out of my sails, if I may be allowed the metaphor, and I look with a twinge of melancholy at the images of Saturn and her moons being transmitted by the Cassini craft — and particularly the one in which Alpha Centauri gleams in the perpetual night sky far beyond the great planet’s rings (http://saturn.jpl.nasa.gov/index.cfm).

MING THE MERCILESS Charles Middleton

A friend of mine told me a couple of years ago that her employer had reserved a place for her on a voyage into space as soon as such a thing became available to consumers. That would have been all right as far as it went, but the trip envisioned would have been a little more than 300 miles each way. My ambition far exceeded that, and Kaku has made it clear that I was deluding myself.

Well, it was a relatively short time ago that some of the ideas that Kaku fools around with — such as an electron that can be in two places at the same time — were not only unknown but unimagined. So rather than put my vacation to Alpha Centauri out of my mind, I’ll put it on hold. After all, I’m only 66 years old. In the meantime, I still have to see the Grand Canyon.

CASSINI VIEW OF ALPHA CENTAURI OVER THE RINGS OF SATURN

Um breve comentário: a edição deste mês da physics theory World é dedicada a interface da Física e Biologia. No blog anteriormente eu falei sobre como os experimentos com pinça óptica permitiram enorme avanço na compreensão das máquinas biológicas moleculares. Na physics theory World há matérias interessantes sobre neurociência e mecânica quântica da vida — essa útlima escrita por Paul Davies.