El asteroide que se aproxima a la Tierra tiene su propia luna

31 de mayo de 2013: El asteroide 1998 QE2 que se aproxima a la Tierra tiene una luna. Los investigadores la encontraron en una secuencia de imágenes de radar obtenidas a través de la antena de 70 metros de la Red del Espacio Profundo (Deep Space Network, en idioma inglés), ubicada en Goldstone, California, en la tarde del 29 de mayo (30 de mayo hora universal), cuando el asteroide se encontraba a unos 6 millones de kilómetros de la Tierra.

La estimación preliminar del tamaño del satélite del asteroide es de aproximadamente 600 metros de ancho. El asteroide en sí posee un diámetro de alrededor de 2,7 kilómetros y tiene un período de rotación de menos de cuatro horas.

Las primeras imágenes de radar del asteroide 1998 QE2 se obtuvieron cuando el asteroide estaba a aproximadamente 6 millones de kilómetros (3,75 millones de millas) de distancia de la Tierra. El conjunto de las imágenes de radar grabadas abarca algo más que dos horas. Crédito de la imagen: NASA/JPL-Caltech/GSSR

Las observaciones que se llevaron a cabo mediante un radar fueron lideradas por la científica Marina Brozovic, del Laboratorio de Propulsión a Chorro (Jet Propulsion Laboratory o JPL, por su sigla en idioma inglés), de la NASA, ubicado en Pasadena, California.

Estos hallazgos muestran que el 1998 QE2 es un asteroide binario. En la población de objetos cercanos a la Tierra, alrededor del 16 por ciento de los asteroides de 200 metros de ancho o más son sistemas binarios o triples. También se revelan en las imágenes de radar obtenidas de 1998 QE2 varias características superficiales oscuras que sugieren grandes concavidades.

El máximo acercamiento del asteroide se producirá el 31 de mayo a la 1:59 de la tarde, hora del Pacífico (4:59 de la tarde, hora del Este / 20:59 GMT), cuando el asteroide llegará a estar a una distancia no mayor que aproximadamente 5,8 millones de kilómetros, o lo que equivale a alrededor de 15 veces la distancia que existe entre la Tierra y la Luna. Este es el máximo acercamiento que el asteroide hará a la Tierra durante al menos los próximos dos siglos. El asteroide 1998 QE2 fue descubierto el 19 de agosto de 1998 por el programa Lincoln de Investigación de Asteroides Cercanos a la Tierra (Lincoln Near Earth Asteroid Research o LINEAR, por su acrónimo en idioma inglés), del Instituto de Tecnología de Massachusetts, ubicado cerca de Socorro, Nuevo México.

La resolución de estas imágenes iniciales del asteroide 1998 QE2 es de aproximadamente 75 metros por píxel. Se espera que la resolución aumente en los próximos días a medida que se disponga de más datos. Entre el 30 de mayo y el 9 de junio, los astrónomos que utilizan radares llevarán a cabo una amplia campaña de observaciones en el asteroide 1998 QE2 mediante el uso de la antena de la Red del Espacio Profundo, que se encuentra en Goldstone, California y a través del Observatorio de Arecibo, en Puerto Rico. Los dos telescopios tienen capacidades de imagen complementarias, lo que permitirá a los astrónomos aprender tanto como sea posible sobre el asteroide durante su breve visita cerca de la Tierra.

Manténgase atento para obtener actualizaciones sobre el tema.

Créditos y Contactos
Funcionaria Responsable de NASA: Ruth Netting Editor de Producción: Dr. Tony Phillips	Traducción al Español: Ángela Atadía de Borghetti Editora en Español: Angela Atadía de Borghetti Formato: Ángela Atadía de Borghetti

Más información

La NASA le otorga una alta prioridad al seguimiento de asteroides y considera que proteger a nuestro planeta de ellos es también de suma importancia. De hecho, Estados Unidos cuenta con el programa más potente y productivo de sondeo y detección de la localización de objetos cercanos a la Tierra. Hasta la fecha, mediante recursos estadounidenses, se han descubierto más del 98 por ciento de los conocidos Objetos cercanos a la Tierra.

En el año 2012, el presupuesto para la monitorización de los objetos cercanos a la Tierra pasó de 6 millones de dólares a 20 millones de dólares. Literalmente, docenas de personas están involucradas en algún aspecto de la investigación de los objetos cercanos a la Tierra a través de la NASA y de sus centros. Por otra parte, hay muchas más personas comprometidas con la investigación y la comprensión de la naturaleza de los asteroides y cometas, incluyendo a aquellos objetos que se acercan a la Tierra, más los que intentan encontrarlos y seguirlos en primer lugar.

Además de disponer de los recursos para la comprensión de los asteroides, la NASA también se asocia con otras agencias del gobierno de Estados Unidos, así como con astrónomos de universidades e institutos de ciencias espaciales de todo el país, que están trabajando para hacer un seguimiento y lograr una mejor comprensión de estos objetos, a menudo con subsidios, transferencias interinstitucionales y otros contratos con la NASA.

El programa de Objetos Cercanos a la Tierra, de la NASA, en la sede central ubicada en Washington, gestiona y financia la búsqueda, el estudio y el seguimiento de asteroides y cometas cuyas órbitas los traen periódicamente cerca de la Tierra. El JPL dirige la Oficina del Programa de Objetos Cercanos a la Tierra para el Directorio de Misiones Científicas de la NASA, en Washington. El JPL es una división del Instituto de Tecnología de California, en Pasadena.

Fuente: Noticias Ciencia de la NASA

Sequestration Impacts Astronomy, Space Science

NEWS BLOG by Mark Zastrow

From international travel to interplanetary probes, the U.S. budget cuts are having major impacts on both ground- and space-based astronomy.

Vinoth Chandar/flickr

In early May, a brief announcement appeared on the website of NASA’s Kepler mission. It read, in full: “The Kepler Science Conference originally scheduled for fall 2013 has been cancelled.” Left unsaid was the reason why, which could have been even briefer: “Due to sequestration.”

Astronomers took to Twitter to voice their dismay as word spread. “Arguably one of NASA’s most successful recent missions finding Earth-sized planets, and scientists can’t get together to discuss,” tweeted Caltech’s Peter Plavchan. The conference would have brought hundreds of astronomers to NASA’s Ames Research Center in California to present and discuss the satellite’s most recent results. Instead, it became the latest sign of how U.S. astronomy and space science will suffer from the federal sequestration cuts.

The abrupt, mandatory reductions fall against the backdrop of an already turbulent fiscal scenario, and unless it is lifted, it will turn the budget screws even tighter on the two largest U.S. government funding agencies for astronomy: the National Science Foundation (NSF) and NASA. If left unchecked, scientists and administrators warn of dire consequences for the nation’s scientific and economic competitiveness.

NSF Researchers Will Feel Cuts

NSF funding forms the public backbone of U.S. ground-based astronomy, underwriting national facilities open to all U.S. astronomersand awarding about $80 million in research grants in fiscal year 2012. Sequestration cut NSF’s FY 2013 overall budget by approximately 5%. It’s not yet known how exactly it will fall across its science divisions, but James Ulvestad, director of the agency’s astronomy division says, “The most immediate impact will be on our small- and mid-scale research grants programs.” All existing grants will be honored in full, but Ulvestad estimates that the number of new grants awarded, already heavily oversubscribed, will fall by about 15 to 30% in FY 2013. Not only will established researchers suffer, but also “fewer graduate students will get support, and fewer postdoctoral fellows will get support,” says Joel Parriott, director of public policy for the American Astronomical Society (AAS).

If sequestration were to remain in effect indefinitely, Ulvestad anticipates a laundry list of dangerous effects. The lack of research grants might cede the most exciting discoveries on its own facilities to researchers elsewhere. A shortfall of infrastructure funding might threaten the construction of the large facilities recommended by U.S. astronomers’ 2010, once-a-decade roadmap, including the Large Synoptic Survey Telescope. And the NSF cuts are only part of the broader federal science budget, “reducing a position of world leadership and imperiling the training of a new generation of STEM professionals.”

Sequester Curtails NASA’s Outreach, Conferences

One of NASA’s first responses to its mandatory 5% cut was the March suspension of education and public-outreach activities. This prompted an outcry from the educators and writers employed by NASA missions to relate their findings to the taxpaying public. The situation was somewhat eased by the announcement of wide-ranging exemptions, though many say it only muddled the issue further, making it difficult to estimate the reduction’s true impact. (Read a sampling of the responses here.)

Attendees at the National Radio Astronomy Observatory exhibit booth at this January's meeting of AAS in Long Beach. Next week's meeting in Indianapolis will be affected by the sequester cuts.

NRAO

Perfectly evident, however, are the effects of the restrictions on conference-related travel that followed, eliminating international travel and preventing more than 50 NASA personnel from attending any single conference. Next week’s meeting of the American Astronomical Society is just one conference that has shrunk in the absence of NASA scientists and exhibitors. The effects multiply: Attending scientists who would normally be at their peers’ talks will instead have to multitask by staffing exhibits, according to Debbie Kovalsky, AAS’s exhibits coordinator. And commercial vendors whose clients will no longer be there have decided to skip it or downsize their presence as well.

NASA managers have further announced a string of cancelled conferences aside from December’s Kepler Science Conference, including a data calibration meeting for Hubble results and the annualSagan Exoplanet Summer Workshop.

“Conferences are where part of the scientific process happens,” says Peter Plavchan, who has authored four papers using Kepler data. “Canceling this conference will slow down the process of discovery, and taxpayers won’t get the most new discoveries for their dollar as a result.”

“NASA spends $98M a year to operate Hubble,” noted the scientists on the astrophysics subcommittee of NASA’s Advisory Council in an April letter. “Canceling a Hubble science conference saves only $50K, but diminishes the science impact of Hubble. This is simply not cost effective.”

Planetary Science Fights For Funds

Perhaps the most politically embroiled impact of sequestration on space science has been the budget figure for NASA’s solar-system division, responsible for successes like the Cassini probe at Saturn and the recent run of rovers on Mars. Planetary science has weathered severe cuts in recent years caused in part by cost overruns of the James Webb Space Telescope (JWST), prompting what Nature News described as “internecine warfare” between supporters of astrophysics and planetary missions.

The Obama administration’s FY 2013 budget request slashed planetary funding by more than 20%, to less than $1.2 billion. But a bipartisan group of supporters in Congress countered by inserting an additional $222 million into its FY 2013 appropriations bill, which President Obama signed in March.

However, sequestration offered NASA an opportunity to reshape its appropriations internally. Instead of spreading the cuts across all divisions equally, NASA’s operating plan for the rest of FY 2013 singles out planetary science for a 15% cut, according to a copy obtained by Mark Sykes of the Planetary Science Institute. The result wipes out all but $3.7 million of the additional $222 million allocated by Congress.

In other words, says Sykes, the Obama administration and NASA used the sequestration cuts as a means to evade Congressional intent. “To come in and sweep away more than 98% of the funds added by Congress and signed into law was very surprising,” Sykes told me. “I thought it was disdainful.” Casey Dreier of the Planetary Society did little to hide his shock in a blog post titled, “NASA Robs Planetary Science.”

NASA’s plan did retain good news for some planetary scientists — $66 million in funds for studies of a potential flagship mission to Jupiter’s icy moon Europa, whose subsurface ocean is one of the most enticing places to search for extraterrestrial life. However, instead of using the money that Congress had allocated for it, NASA and the administration effectively took it out of other programs, dropping them below the President’s proposed FY 2013 levels, including competitive research grants and smaller missions under the Discovery and New Frontiers programs. “Rob Peter to pay Paul, is what it is,” Sykes lamented. While he’s not opposed to a Europa mission, “additional studies should be funded by additional monies — not at the expense of research, Discovery, or New Frontiers.”

This challenging fiscal environment shows no sign of abating: in the President’s FY 2014 request, planetary science again came up $200 million short of the FY 2013 level allocated by Congress in March. In what educators say is a further attack on science education, it also proposes removing all NASA-related education and outreach from the space agency’s purview and reconstituting it under the Department of Education and the Smithsonian. The goal is to improve efficiency, but many say it would destroy the existing networks between educators and scientists and even backfire. “This will likely necessitate new layers of personnel to interface between NASA scientists and educational professionals,” noted NASA’s astrophysics advisory subcommittee. Altogether, these developments paint a bleak picture for many. “I’m not sure what the administration’s plans for the future are,” says Sykes. “But if it involves decimating our capability [as a nation], I think they’re taking the right steps.”

NSF Divestment Continues

The 4-meter Mayall Telescope dominates the skyline of the Kitt Peak National Observatory.

Govert Schilling

One thing the sequester will not affect, says James Ulvestad, is NSF’s ongoing plan to divest its interests in several ground-based facilities, including the Green Bank Telescope, the Very Long Baseline Array, and three optical telescopes at Kitt Peak National Observatory (KPNO) in Arizona. (This is a result of a 2012portfolio review assessing NSF Astronomy’s long-term financial picture.) “That timescale was set up to provide a reasonable (but not excessive) period of time to enable new partnerships and new operations models to develop,” says Ulvestad.

At Kitt Peak, where NSF acts as the observatory’s landlord, the Department of Energy and the University of California-Berkeley are currently interested in such a partnership to use the Mayall 4-meter telescope to conduct an all-sky dark-energy survey. A private grant will fund the construction of the instrument, but ultimately, the decision to fund the project remains with DOE. “Optimism for the future is considerably higher today than it was a year ago,” says KPNO’s director, Timothy Beers. “But if you ask me today, ‘Will Kitt Peak be a living, viable observatory doing astronomical research 10 years from now?’, I will know better in a year or two… I can’t say what the path toward that is.”

Posted By Mark Zastrow, May 31, 2013

Source: SKY and TELESCOPE

Quantum gravity takes singularity out of black holes

• 12:17 29 May 2013 by Katia Moskvitch
• For similar stories, visit the Cosmology Topic Guide

Falling into a black hole may not be as final as it seems. Apply a quantum theory of gravity to these bizarre objects and the all-crushing singularity at their core disappears.

In its place is something that looks a lot like an entry point to another universe. Most immediately, that could help resolve the nagging information loss paradox that dogs black holes.

Though no human is likely to fall into a black hole anytime soon, imagining what would happen if they did is a great way to probe some of the biggest mysteries in the universe. Most recently this has led to something known as the black hole firewall paradox – but black holes have long been a source of cosmic puzzles.

According to Albert Einstein's theory of general relativity, if a black hole swallows you, your chances of survival are nil. You'll first be torn apart by the black hole's tidal forces, a process whimsically named spaghettification.

Eventually, you'll reach the singularity, where the gravitational field is infinitely strong. At that point, you'll be crushed to an infinite density. Unfortunately, general relativity provides no basis for working out what happens next. "When you reach the singularity in general relativity, physics just stops, the equations break down," says Abhay Ashtekar of Pennsylvania State University.

The same problem crops up when trying to explain the big bang, which is thought to have started with a singularity. So in 2006, Ashtekar and colleagues applied loop quantum gravity to the birth of the universe. LQG combines general relativity with quantum mechanics and defines space-time as a web of indivisible chunks of about 10^-35 metres in size. The team found that as they rewound time in an LQG universe, they reached the big bang, but no singularity – instead they crossed a "quantum bridge" into another older universe. This is the basis for the "big bounce" theory of our universe's origins.

Information paradox

Now Jorge Pullin at Louisiana State University and Rodolfo Gambini at the University of the Republic in Montevideo, Uruguay, have applied LQG on a much smaller scale – to an individual black hole – in the hope of removing that singularity too. To simplify things, the pair applied the equations of LQG to a model of a spherically symmetrical, non-rotating "Schwarzschild" black hole.

In this new model, the gravitational field still increases as you near the black hole's core. But unlike previous models, this doesn't end in a singularity. Instead gravity eventually reduces, as if you've come out the other end of the black hole and landed either in another region of our universe, or another universe altogether. Despite only holding for a simple model of a black hole, the researchers – and Ashtekar – believe the theory may banish singularities from real black holes too.

That would mean that black holes can serve as portals to other universes. While other theories, not to mention some works of science fiction, have suggested this, the trouble was that nothing could pass through the portal because of the singularity. The removal of the singularity is unlikely to be of immediate practical use, but it could help with at least one of the paradoxes surrounding black holes, the information loss problem.

A black hole soaks up information along with the matter it swallows, but black holes are also supposed to evaporate over time. That would cause the information to disappear forever, defying quantum theory. But if a black hole has no singularity, then the information needn't be lost – it may just tunnel its way through to another universe. "Information doesn't disappear, it leaks out," says Pullin.

Journal reference: Physical Review Letters, doi.org/mnm

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Title:		Conspiratorial cosmology - the case against the Universe
Authors:		Rachen, Jörg P.; Gahlings, Ute G.
Publication:		eprint arXiv:1303.7476
Publication Date:		03/2013
Origin:		ARXIV
Keywords:		Physics - Popular Physics, Astrophysics - Cosmology and Extragalactic Astrophysics, High Energy Physics - Phenomenology
Comment:		4 pages; Journal of Comparative Irrelevance (Letters), Vol 23, p. 966 (April 2013)
Bibliographic Code:		2013arXiv1303.7476R

Abstract

Based on the cosmological results of the Planck Mission, we show that all parameters describing our Universe within the \Lambda CDM model can be constructed from a small set of numbers known from conspiracy theory. Our finding is confirmed by recent data from high energy particle physics. This clearly demonstrates that our Universe is a plot initiated an unknown interest group or lodge. We analyse possible scenarios for this conspiracy, and conclude that the belief in the existence of our Universe is an illusion, as previously assumed by ancient philosophers, 20th century science fiction authors and contemporary film makers.

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Eric Weinstein’s theory may explain why the universe works the way it does

May 25, 2013

by Dave Gamble

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The first most obvious question might be who? Well, Eric Weinstein is a Harvard math Ph. D. who has been working as an economist in New York.

The news here is that he has been working on some of his own far out of the mainstream ideas about geometry and physics for decades, and … no wait, don’t roll you eyes and sigh, “another crank”, because what he has is interesting enough to be of interest to some. He gave a lecture in Oxford, something that was arranged by Marcus du Sautoy (the Simonyi Professor for the Public Understanding of Science and a Professor of Mathematics at the University of Oxford).

Now, before we go any further, how has the media reacted?

• The Guardian has a long gushing article about him and his work here (written by Marcus du Sautoy himself), and another one here.
• New Scientist has a skeptical take here.
• Jennifer Ouellette has a critical take on the Guardian coverage

OK, so what exactly is the claim?

I’ll not go too far into the details, but basically New Scientist puts it like this …

…all the problems plaguing physics have been solved. Dark matter, dark energy, quantum gravity – one amazing insight has delivered us from decades of struggle to a new knowledge nirvana.

And of course there is a wee problem …

I’m unable to tell you what that insight is. Neither I, nor any of my professional physicist friends, have the faintest clue. In fact, nobody except Eric Weinstein and mathematician Marcus du Sautoy are sufficiently familiar with the claims to venture an opinion.

If this all sounds familiar, then you would be right it is indeed, for here we have science being done by press release (Hint: cold fusion), and also a lecture. As Marcus du Sautoy explains, “I’m trying to promote, perhaps, a new way of doing science. Let’s start with really big ideas, let’s be brave and let’s have a discussion,” … er, that might not be such a good idea …

If you are going to give a presentation in the Physics department at Oxford university that claims to discuss a solution that solves many of today’s big physics problems, it might actually have been a cool idea to invite a few of the resident Oxford physicists. They were close by in a room not too far away listening to another speaker talk about a new source of CP violation in charm physics, and no they did not boycott this, they simply were not invited.

So lets suppose they had been, how exactly would that “discussion” have worked? Because there are no published papers on any of this, the nitty-gritty mathematical details would have been … “surprise surprise … here you go”. But this is not the sort of stuff you can discuss without actually pondering over it first.

Even if it is all true and factual and Mr Weinstein has indeed truly got a good idea (that is still a possibility), a press story is not the way you do science. I would have thought that the cold fusion fiasco would have taught us that lesson long ago … but apparently not.

It does perhaps in some ways also remind me of Garrett Lisi, the surfer and theoretical physicist who gained fame at one point for his “An Exceptionally Simple Theory of Everything,” paper that proposed a unified field theory based on the E₈ Lie group, combiningparticle physics with Einstein’s theory of gravitation. It drummed up a lot of excitement at the time (2007), but is not widely accepted by the physics community. Why not? Well because his theories are incomplete and did not make enough predictions that could be tested in experiments. Mt Lisi himself does acknowledge this and states that his paper “cannot be considered much more than a speculative proposal“.

Garrett himself commented yesterday on Eric Weinstein’s work as follows …

Eric’s been working on this for a long time — I’m happy he’s now publicly airing some of his ideas. And I’m looking forward to seeing what he puts on the arXiv.

So what comes next?

The watch words are “Paper, or it didn’t happen”, and so Mr Weinstein plans to put a manuscript on the Arxiv preprint server.

Ah but what do the Subject matter experts think?

Well, this is where it gets interesting, because those that have dug into all this do find that it has merit, in other words he is not just a crank, there may real substance and coherence here …

David Kaplan, a particle theorist at Johns Hopkins University in Baltimore, has seen and discussed some of Weinstein’s ideas with him. On the plus side, Kaplan says it is “phenomenal” that someone coming from outside academia could put together something so coherent. “There are many people who come from the outside with crazy theories, but they are not serious. Eric is serious.”

But he says the theory is incomplete and should have spent more time being critiqued by academics before receiving any wider public attention. “What I would encourage him to do is modest things and take steps and commit to a physical manifestation of his theory – to say ‘here is a set of instructions and a set of equations, do this calculation and you can make the following predictions.’ And then see if his theory matches with the real world or not. He doesn’t have enough of a case. What I’d like him to do is to keep working.”

Edward Frenkel, a mathematician at the University of California, Berkeley, has been discussing Weinstein’s ideas with him for the past year. “I think that both mathematicians and physicists should take Eric’s ideas very seriously,” he says. “Even independently of their physical implications, I believe that Eric’s insights will be useful to mathematicians, because he points to some structures which have not been studied before, as far as I know. As for the physical implications, it is quite possible that this new framework will lead to new answers to the big questions, after necessary work is done to make precise predictions which can be tested experimentally.”

Jim al-Khalili, a nuclear physicist at the University of Surrey who has seen a summary of Weinstein’s ideas (but not the maths) is sceptical. He says Weinstein will need to do a “heck of a lot of convincing” if he wants physicists to take his ideas seriously. “My main concern with Weinstein’s claims is that they are simply too grand – too sweeping. It would be one thing if he argued for some modest prediction that his theory was making, and importantly one that could be tested experimentally, or that it explained a phenomenon or mechanism that other theories have failed to do, but he makes the mistake of claiming too much for it.”

So while he may indeed have got off on the wrong foot here by attempting to engage in a rather odd way with the community, what he has is sufficiently interesting to motivate some to have an interest here.

So is it really possible for an outsider to have ideas which fundamentally alter our world view, no of course not. Oh wait, there was some chap who worked as a clerk in a patent office in Switzerland, now what was his name again? OK, that is too simplistic, our Swiss clerk had a Ph.D and had already published other papers, so yes we are back to the missing bit here …

“Paper, or it didn’t happen”

Final Word

Andrew Pontzen a cosmologist at the University of Oxford and University College London comments on all this by writing in New Scientist …

At what point during this long and difficult process does it become legitimate to proclaim a breakthrough? It’s a line in shifting sands, but that line has certainly been crossed. Du Sautoy – the University of Oxford’s professor of the public understanding of science, no less – has short-circuited science’s basic checks and balances. Yesterday’s shenanigans were anything but scientific.

But to be strictly fair, if interested in the details of Mr Weinstein’s thinking, then you can read about it here in Mr Du Sautoy’s Guardian article (but remember to digest with a pinch of salt). Or perhaps also by browsing his 2012 Edge article here (you will need to scroll down to find it).

Source: http://www.skeptical-science.com/science/eric-weinsteins-theory-explain-universe-works/

¿Qué es la Nada? Debaten los físicos

Pedro Donaire

 

3/24/2013 08:20:00 a.m.

FilosofiaFísica

Referencia: Live.Science.com .

por Clara Moskowitz, 22 de marzo 2013

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Cuando los físicos y pensadores se reunieron el 20 de marzo para debatir sobre el concepto de la nada, en el Museo Americano de Historia Natural, todo parecía hacer mucho ruido y haber pocas nueces.

La simple idea de la nada, un concepto que incluso los niños pequeños pueden entender, resultó ser para los científicos sorprendentemente difícil de precisar, e incluso algunos de ellos preguntaban si tal cosa existe.

La primera y más básica idea sobre la nada -un espacio vacío sin nada en éḷ-, se acordó rápidamente que no es nada: En nuestro universo, incluso un vacío oscuro y ausente de espacio, sin ningún tipo de partículas, todavía es algo.

"Tiene una topología, tiene una forma, es un objeto físico", declaraba el filósofo Jim Holt durante el Debate anual en memoria de Isaac Asimov del Museo, que este año se centró en el tema "La Existencia de la Nada".

Como moderador Neil deGrasse Tyson, director del Planetario Hayden del Museo, dijo: "Si las leyes de la física se pueden seguir aplicando a la nada" [Vacío infinito o Gran Colapso (Big Crunch): ¿Cómo terminará el Universo]

Profunda nada

Pero hay un tipo más profundo de nada, sostenía el físico teórico Lawrence Krauss, de la Universidad Estatal de Arizona, que consiste en no hay espacio en absoluto, ni tiempo, ni partículas, ni campos, ni leyes de la naturaleza. "Eso para mí es lo más parecido a la nada que se puede llegar", dijo Krauss.

Jim Holt mostraba su desacuerdo. "¿Es que realmente no hay nada?", se preguntó. "No hay espacio y no hay tiempo; pero ¿qué pasa con las leyes físicas, ¿qué pasa con las entidades matemáticas? ¿Qué pasa con la conciencia? Todas las cosas que son no-espaciales y no temporales."

Otros oradores ofrecieron ideas diferentes para la nada, como el concepto matemático de nada presentado por el periodista científico Charles Seife, autor de "Zero: La Biografía de una Idea Peligrosa" (Penguin Books, 2000). Propuso empezar con un conjunto de números que incluyan sólo el número cero, entonces eliminar el cero, dejando lo que se llama un conjunto nulo. "Es casi una nada platónica", señaló.

El físico teórico Eva Silverstein, de la Universidad de Stanford sugiere una nada muy técnica, basada en la teoría cuántica de campos, que involucraba un sistema cuántico carente de grados de libertad (dimensiones). "El estado fundamental de un sistema cuántico con huecos (sin espacios intermedios) es mi mejor respuesta", dijo.

Holt sugirió otra idea de nada.

"Una imagen, sólo remotamente persuasiva de la nada, se la he oído decir al físico Alex Vilenkin", un físico de la Universidad de Tufts, contaba Holt. "Imagina la superficie de una bola. Es un espacio finito pero sin límites. Entonces imagina que se contrae en un punto". Eso crearía un espacio cerrado de radio cero.

La ausencia de algo

Sin embargo, Holt dijo que no se ganaba nada con esa definición tampoco, y no estaba convencido de que la nada existiese realmente.

"Los filósofos analíticos dicen que la nada es un nombre, y que parece el nombre de una entidad, pero que no lo es, simplemente no significa nada", dijo "¿Qué hace tan especial a la nada? No es una noción filosófica fructífera."

Pero sólo porque la nada sea francamente difícil de conceptualizar, no quiere decir que no sea una cosa real, rebatió Krauss. "Hay un montón de cosas en la ciencia que resultan imposibles de manejar de forma intuitiva, pero eso no quiere decir que no exista", dijo Krauss.

Esta dificultad en la comprensión de la nada se remonta a tiempos muy lejanos. Los antiguos griegos no tenían ninguna idea del cero, y odiaban tanto la idea que se negaron a incorporar el cero en su sistema numérico, aún cuando sus cálculos astronómicos lo requerían.

"Los seres humanos tenemos una auténtica aversión a la nada, al vacío", apuntó Seife. "Para nosotros, la nada representa algo que nos da miedo, representa el desorden, la ruptura de las reglas".

En última instancia, la definición de la nada sólo puede ser un blanco en constante movimiento, que irá cambiando con cada revolución científica, conforme las nuevas concepciones nos vayan mostrando lo que pensábamos de la nada, si es realmente algo.

"Tal vez, el problema de la nada nunca será resuelto", dijo Tyson.

---

- Imagen del vacío, la nada. 

Autor: Pedro Donaire, Bitnavegntes

Inflationary paradigm in trouble after Planck2013

Anna Ijjas, Paul J. Steinhardt, Abraham Loeb

(Submitted on 9 Apr 2013)

The recent Planck satellite combined with earlier results eliminate a wide spectrum of more complex inflationary models and favor models with a single scalar field, as reported in the analysis of the collaboration. More important, though, is that all the simplest inflaton models are disfavored by the data while the surviving models -- namely, those with plateau-like potentials -- are problematic. We discuss how the restriction to plateau-like models leads to three independent problems: it exacerbates both the initial conditions problem and the multiverse-unpredictability problem and it creates a new difficulty which we call the inflationary "unlikeliness problem." Finally, we comment on problems reconciling inflation with a standard model Higgs, as suggested by recent LHC results. In sum, we find that recent experimental data disfavors all the best-motivated inflationary scenarios and introduces new, serious difficulties that cut to the core of the inflationary paradigm. Forthcoming searches for B-modes, non-Gaussianity and new particles should be decisive.

Subjects:	Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
DOI:	10.1016/j.physletb.2013.05.023
Cite as:	arXiv:1304.2785 [astro-ph.CO]
	(or arXiv:1304.2785v1 [astro-ph.CO] for this version)

Submission history

From: Anna Ijjas [view email]
[v1] Tue, 9 Apr 2013 20:15:58 GMT (253kb)

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