Seminario sobre George Lemaitre,padre de la Teoria del Big Bang

UNIVERSIDAD DE NAVARRA.- 

Mié, 26/01/2011 - 09:39

Sección: Ciencias, Religión, Teología

“El relativismo es el cáncer de la ciencia: si no se tiene fe en lo que se busca, difícilmente se puede acceder a ello”

Eduardo Riaza, miembro de la Real Sociedad Española de Física, impartió un seminario sobre el padre de la Teoría del Big Bang, organizado por el Grupo de Investigación “Ciencia, Razón y Fe” de la Universidad de Navarra

Eduardo Riaza.

Foto: Manuel Castells

Eduardo Riaza Molina, miembro de la Real Sociedad Española de Física y profesor de Física y Química en el Colegio Retamar de Madrid, impartió un seminario del Grupo de Investigación “Ciencia, Razón y Fe” de la Universidad de Navarra.
En la sesión sobre “El Universo de George Lemaître”, repasó el perfil y aportaciones de este astrofísico y sacerdote católico, padre de la Teoría del Big Bang. Eduardo Riaza ha publicado recientemente la primera biografía en castellano de este científico bajo el título La historia del comienzo.
Blog de Eduardo Riaza sobre Georges Lemaître

-Grandes investigadores como Lemaître estuvieron muy influidos por la Filosofía. ¿Percibe también esta tendencia en los científicos actuales o hay una deficiencia en su formación y la perspectiva en este sentido?

El campo es muy amplio. Algunos científicos obvian la Filosofía y otros la tienen en cuenta, pero quizá su formación en este campo dista mucho de la Filosofía realista de Tomás de Aquino que tenía presente Lemaître. Ésta le permitió llegar a un buen ajuste entre las hipótesis teóricas propuestas por Einstein y las observaciones astronómicas. El relativismo que a veces se ve en la ciencia o en los científicos es el cáncer de la ciencia: si no se tiene fe en lo que se busca, difícilmente se puede acceder a ello.

-La Teoría del Big Bang fue propuesta por Lemaître, un sacerdote católico. Sin embargo, actualmente algunos piensan que es contraria a la existencia de Dios. ¿Cómo se ha producido esta paradoja?

Georges Lemaître es muy poco conocido; de hecho, prácticamente no hay referencias sobre él en las bibliotecas españolas, tal y como constaté cuando escribí su biografía. Quienes han trabajado en el mismo terreno que él evitan nombrarle. Esto quizá se deba a un prejuicio religioso y, especialmente, ante el católico. No obstante, tampoco es adecuado convertirle en un abanderado de la apologética, tal y como él rechazó. Así lo demuestra el hecho de que escribiera a los colaboradores del Papa Pío XII tras un discurso de éste en el que daba a entender que la teoría de Lemaître apoyaba la idea de la Creación. No quería mezclar ambos aspectos.

George Lemaître y Albert Einstein.

Foto: Cedida

- Lemaître fue un ejemplo de vocación científica temprana. ¿Cuál es la fórmula para despertarla entre los jóvenes? ¿Es posible hacerlo sólo desde los aspectos más técnicos?

Hoy en día existe una gran falta de vocaciones científicas y se están empleando muchos recursos para resolverlo. El problema es que, ante esa dificultad, se da una respuesta equivocada: la ciencia fácil, accesible para todos. Hay que divulgar, pero no rebajando el nivel ni perdiendo rigor. De hecho, habría que elevar los estudios. La tendencia de las leyes de educación es igualar por abajo. Así, la atención a la diversidad se suele centrar en los que van mal, descuidando a aquellos que destacan. Por otro lado, pienso que no se debe hacer división entre ciencias y letras: desde edades tempranas se tendría que potenciar la lectura, la contemplación de la naturaleza, o el disfrute del teatro. Si aludimos a las vidas de científicos como Einstein o Lemaître, entre otros, vemos que además de esa faceta tenían otra humanística; tocaban algún instrumento musical, eran artistas...

-Con Lemaître se demuestra que excelencia científica y fe son compatibles. ¿Qué puede enseñar su figura a los científicos de hoy?

Aunque su personalidad fue muy rica, destacaría su sentido del humor y, especialmente, su amor a la verdad. Además, nunca tuvo prejuicios: planteó un modelo infinito en el tiempo que era, supuestamente para algunos, incompatible con la revelación. Pero como filosóficamente no veía inconvenientes, no tuvo problemas en admitirlo. Esa libertad de pensamiento puede ser un gran ejemplo para otros.

-¿Qué papel deben tener en la sociedad los científicos católicos?

En primer lugar, tienen que ser muy buenos científicos. Luego resulta vital que se impliquen en la divulgación. Ésta no da tanto prestigio como la publicación en revistas especializadas, pero tiene gran impacto en la sociedad. El concepto que puede tener el ciudadano de a pie de lo que es la ciencia se aleja de lo que ésta es en realidad. Además, sus creencias están teñidas de la moda New Age y de supersticiones o aspectos paracientíficos que no tienen ninguna entidad. Por ejemplo, se cree con más fuerza en cosas como la ‘energía positiva’ que en la ciencia empírica o en Dios.

-¿Cómo calificaría la divulgación científica que se hace en la actualidad?

Por un lado, en muchas ocasiones se usa para atacar a la Iglesia desde algunos aspectos o, al menos, busca la confrontación. Por ejemplo, salen a colación casos como el de Galileo, vistos desde una perspectiva sesgada. Sin hacer una cruzada, hay que exponer las cosas para que la historia se escriba con objetividad. No hay que generar polémicas ni reivindicaciones, pero sí ser justos con los protagonistas, evitando los prejuicios.

Adjuntos: 

lemaitre.pdf

Etiquetas:  astrofisica, big bang, cryf, eduardo riaza, georges lemaitre, santiago collado, universo

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3. Expertos en neurociencia y filosofía se dan cita en el Instituto Cultura y Sociedad de la Universidad de Navarra
4. El subdirector y tres miembros colaboradores del CRYF de la Universidad de Navarra participan en un workshop en Roma
5. Un astrofísico defiende en la Universidad de Navarra el diálogo entre Física y Filosofía en el estudio del universo

A Galaxy when Galaxies Were Young

News media worldwide are reporting today on a new “farthest galaxy ever found,” courtesy of the Hubble Space Telescope, but the discovery is not quite as definite as it’s being made out. In a study characterized more by a process of elimination than positive identification, the astronomers involved estimate that there’s about an 80% chance they've got it right.

UDFj-39546284 as seen in Hubble Ultra Deep Field 2009-2010, taken with the aid of Hubble Space Telescope’s Wide Field Camera 3. Click image for wider view.

NASA, ESA, G. Illingworth and R. Bouwens (University of California, Santa Cruz), and the HUDF09 Team.

If their interpretation is correct, light from the tiny, faint galaxy has undergone a redshift of 10.3, meaning the light has been en route to Earth for 13.2 billion years. In looking at this galaxy “We’ve gone back through 96 percent of the life of the universe to 500 million years after the Big Bang,” said Garth Illingworth (University of California, Santa Cruz), who reported the discovery with Rychard Bouwens (University of Leiden) in the January 27th Nature. The object, designated UDFj-39546284 for its location in the Hubble Ultra Deep Field, seems to be just 1% of the size of the Milky Way — typical of the mini-galaxies that presumably filled the early universe. It was visible only at the longest infrared wavelength that Hubble can detect (1.7 microns). “We’re really pushing Hubble to its limits here,” Illingworth said.

With more than 40 hours of exposure time on Hubble’s recently installed Wide Field Camera 3, the team created what Bouwens called “the deepest near-infrared image ever obtained.” Still, the object was so faint that team could not get a spectrum of its light to analyze, the surest way to determine a redshift. They had to rely instead on a photometric redshift estimate, based on comparing the amount of light coming through several of the camera’s wide-spectrum color filters. From such information astronomers can piece together a very rough approximation of the object’s spectrum, though without the narrow spectral lines astronomers usually rely on to measure redshift accurately.

That’s where the process of elimination came in. Since astronomers were limited to a rough approximation of spectrum, there was a much greater risk of misinterpreting the data. With only a photometric level of detail, different types of objects may show the same spectral profile. “You have to make a leap of faith and you ask yourself, ‘What else can it be?’ ” said Rogier Windhorst, a professor at the Arizona State University’s School of Earth and Space Exploration.

According to Windhorst, the mostly likely alternative explanation in this case would be a less distant galaxy reddened by dust. “These galaxies have a spectrum somewhat similar to the source,” Bouwens said. “But only somewhat similar.”

Zoomed-in image of UDFj-39546284, courtesy of the Hubble Space Telescope.

NASA, ESA, G. Illingworth and R. Bouwens (University of California, Santa Cruz), and the HUDF09 Team.

This object showed a very unusual profile, with light only showing up in the reddest filter of the camera’s seven. That’s why both Bouwens and Windhorst are fairly confident they’re really seeing an incredibly distant galaxy; a dusty galaxy closer to home would probably show some emission at other wavelengths. Other interpretations are “not impossible, but not very likely,” Windhorst said.

Observations of ultra-high-redshift galaxies provide important constraints for theories of how the first galaxies formed. Though the Hubble image shows this object as just a tiny smudge, its miniature size itself holds important information about primeval galaxies. The team also concluded that “star birth at 500 million years [after the Big Bang] was astonishingly less than starburst at 600 million years,” Illingworth said.

“For the first time now, we can make realistic statements about how the galaxy population changed during this period,” said Bouwens.

NASA press release.

The researchers' paper.

Posted by Jessica Kloss, January 27, 2011

related content: Cosmology news, Galaxy news - Sky and Telescope

Busqueda de Materia negra en el LHC , Cerca de obtener..?

Hunt for dark matter closes in at Large Hadron Collider

January 26, 2011

One of the earliest CMS events found showing evidence of two jets. The blue and red columns represent energy deposited in the detector, while the yellow curved lines are measured tracks of particles.

(PhysOrg.com) -- Physicists are closer than ever to finding the source of the Universe's mysterious dark matter, following a better than expected year of research at the Compact Muon Solenoid (CMS) particle detector, part of the Large Hadron Collider (LHC) at CERN in Geneva.

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The scientists have now carried out the first full run of experiments that smash protons together at almost the speed of light. When these sub-atomic particles collide at the heart of the CMS detector, the resultant energies and densities are similar to those that were present in the first instants of the Universe, immediately after the Big Bang some 13.7 billion years ago. The unique conditions created by these collisions can lead to the production of new particles that would have existed in those early instants and have since disappeared.
The researchers say they are well on their way to being able to either confirm or rule out one of the primary theories that could solve many of the outstanding questions of particle physics, known as Supersymmetry (SUSY). Many hope it could be a valid extension for the Standard Model of particle physics, which describes the interactions of known subatomic particles with astonishing precision but fails to incorporate general relativity, dark matter and dark energy.
Dark matter is an invisible substance that we cannot detect directly but whose presence is inferred from the rotation of galaxies. Physicists believe that it makes up about a quarter of the mass of the Universe whilst the ordinary and visible matter only makes up about 5% of the mass of the Universe. Its composition is a mystery, leading to intriguing possibilities of hitherto undiscovered physics.
Professor Geoff Hall from the Department of Physics at Imperial College London, who works on the CMS experiment, said: "We have made an important step forward in the hunt for dark matter, although no discovery has yet been made. These results have come faster than we expected because the LHC and CMS ran better last year than we dared hope and we are now very optimistic about the prospects of pinning down Supersymmetry in the next few years."
The energy released in proton-proton collisions in CMS manifests itself as particles that fly away in all directions. Most collisions produce known particles but, on rare occasions, new ones may be produced, including those predicted by SUSY – known as supersymmetric particles, or 'sparticles'. The lightest sparticle is a natural candidate for dark matter as it is stable and CMS would only 'see' these objects through an absence of their signal in the detector, leading to an imbalance of energy and momentum.

Fuente: http://www.physorg.com/news/2011-01-dark-large-hadron-collider.html

La Galaxia mas temprana despues del Big Bang, a 13.2 mil millones de años

About Hubble Orbit View News Background Science Solar System Our Milky Way Beyond The Milky Way Cosmology Spacecraft 3D Model Hubble instruments Engineering Mission Operations Operating Hubble Launch SM 1 SM 2 SM 3A SM 3B SM 4 Timeline Status Reports Science Operations ST-ECF Science Archive Services Publications Conferences Calendar Subscribe Glossary Images and Videos

27-Jan-2011 15:38:16 UT Hubble finds a new contender for galaxy distance record 26 Jan 2011 Pushing the Hubble Space Telescope to the limit of its technical ability, an international collaboration of astronomers have found what is likely to be the most distant and ancient galaxy ever seen, whose light has taken 13.2 billion years to reach us (a redshift of around 10). Astronomers have pushed the NASA/ESA Hubble Space Telescope to its limits by finding what is plausibly the most distant and ancient object in the Universe [1] ever seen. Its light has travelled for 13.2 billion years to reach Hubble [2], which corresponds to a redshift around 10. The age of the Universe is 13.7 billion years. The galaxy UDFj-39546284 may be the most distant, ancient object in the Universe. It appears as a faint red blob in this ultra deep field exposure taken with the NASA/ESA Hubble Space Telescope. Copyright: NASA, ESA, G. Illingworth (University of California, Santa Cruz), R. Bouwens (University of California, Santa Cruz, and Leiden University) and the HUDF09 Team The dim object, called UDFj-39546284, is likely to be a compact galaxy of blue stars that existed 480 million years after the Big Bang, only four per cent of the Universe's current age. It is tiny. Over one hundred such mini-galaxies would be needed to make up our own galaxy, the Milky Way. This galaxy would be more distant than the population of redshift 8 galaxies recently discovered in the Hubble Ultra Deep Field, including the current most distant spectroscopically confirmed [3] record holder at a redshift of 8.6, and the redshift 8.2 gamma-ray burst from 2009. A redshift of z = 8.6 means that the object is seen as it was around 600 million years after the Big Bang. "We're seeing huge changes in the rate of star birth that tell us that if we go a little further back in time we're going to see even more dramatic changes," says Garth Illingworth of the University of California at Santa Cruz. The astronomers were surprised, as this new result suggests that the rate at which galaxies were forming stars grew precipitously, increasing by a factor of ten over the 170 million years that elapsed between the era of this newly discovered candidate galaxy and that of the population of previously identified galaxies at a redshift around 8 (650 million years after the Big Bang). "These observations provide us with our best insights yet into the likely nature of the earlier generation of primeval objects that we are yet to find," adds Rychard Bouwens of Leiden University in the Netherlands. Astronomers don't know exactly when the first stars appeared in the Universe, but every step further from Earth takes them deeper into the early Universe's formative years when stars and galaxies were just beginning to emerge in the aftermath of the Big Bang [4]. "We're moving into a regime where there are big changes afoot. Another couple of hundred million years back towards the Big Bang, and that will be the time when the first galaxies really are starting to build up," says Illingworth. Bouwens and Illingworth are reporting the discovery in the 27 January issue of the British science journal Nature. The even more distant proto-galaxies that the team expects are out there will require the infrared vision of the NASA/ESA/CSA James Webb Space Telescope (JWST), which is the successor to Hubble. Planned for launch later this decade, JWST will provide the spectroscopic measurements that will confirm today's report of the object's tremendous distance. A year of detailed analysis was required before the object was identified in the Hubble Ultra Deep Field - Infrared (HUDF-IR) data taken in the late summers of 2009 and 2010. The object appears as a faint dot of starlight in the Hubble exposures, and although its individual stars canft be resolved by Hubble, the evidence suggests that this is a compact galaxy of hot stars that first started to form over 100-200 million years earlier, from gas trapped in a pocket of dark matter. The proto-galaxy is only visible at the longest infrared wavelengths observable by Hubble. This means that the expansion of the Universe has stretched and thereby reddened its light more than that of any other galaxy previously identified in the HUDF-IR, taking it to the very limit that Hubble can detect. JWST will go deeper into infrared wavelengths and will be at least an order of magnitude more sensitive than Hubble, allowing it to hunt more efficiently for primeval galaxies at even greater distances, at earlier times, closer to the Big Bang. Notes for editors The Hubble Space Telescope is a project of international cooperation between ESA and NASA. [1] The international team of astronomers in this study consists of R. J. Bouwens (Leiden University and University of California, Santa Cruz), G. D. Illingworth (University of California, Santa Cruz), I. Labbe (Carnegie Observatories), P. A. Oesch (ETH Zurich), M. Trenti (University of Colorado), C. M. Carollo (ETH Zurich), P. G. van Dokkum (Yale University), M. Franx (Leiden University), M. Stiavelli (Space Telescope Science Institute), V. González (University of California, Santa Cruz), D. Magee (University of California, Santa Crux) and L. Bradley (Space Telescope Science Institute) [2] Astronomers plumb the depths of the Universe, and probe its history, by measuring how much the light from an object has been stretched by the expansion of space. This is called the redshift value or z. In general, the greater the observed z value for a galaxy, the more distant it is in time and space, as observed from our position in the Milky Way. Before Hubble was launched, astronomers could only see galaxies out to a z of approximately 1, corresponding to an era halfway through the history of the Universe. The original Hubble Deep Field, taken in 1995, leapfrogged to z = 4, or roughly 90 per cent of the way back to the beginning of time. The Advanced Camera for Surveys (ACS) produced the Hubble Ultra Deep Field of 2004, pushing back the limit to z ~ 6. ACS was installed on Hubble during Servicing Mission 3B in 2002. Hubble's first infrared camera, the Near Infrared Camera and Multi-Object Spectrometer reached out to z = 7. The Wide Field Camera 3 (WFC3) first took us back to z ~ 8, and has now plausibly penetrated back for the first time to z = 10. The James Webb Space Telescope is expected to extend this back to a z of approximately 15, 275 million years after the Big Bang, and possibly beyond. The very first stars may have formed between z's of 30 and 15. [3] Likely candidates for distant galaxies can be identified and have their redshift estimated by carefully studying them in Hubble images taken through a range of different filters. The galaxy will be visible only in some of the filters. An estimate of the redshift can be deduced from the colour of the last filter in which the object is detected (a technique known as photometric redshift). However, redshifts can only be confirmed through spectroscopic study, in which the light from a galaxy is split into its constituent wavelengths for analysis. This newly discovered candidate galaxy is too faint to be studied spectroscopically by any telescope in operation today, but the forthcoming NASA/ESA/CSA James Webb Space Telescope will be equipped to do so. [4] The hypothesised hierarchical growth of galaxies — from stellar clumps to majestic spirals and ellipticals — didn't become evident until the Hubble Space Telescope Deep Field exposures. The first 500 million years of the Universe's existence, from a z of 1000 to 10 is now the missing chapter in the story of the hierarchical growth of galaxies. It's not clear how the Universe assembled structure out of a darkening, cooling fireball of the Big Bang. As with a developing embryo, astronomers know there must have been an early period of rapid changes that would set the initial conditions which made the Universe of galaxies what it is today. Contacts Garth Illingworth University of California, Santa Cruz, USA Tel: +1-831-459-2843 Email: gdiucolick.org Rychard BouwensLeiden University, Netherlands and University of California, Santa Cruz, USA Tel: +1-831-459-5276 Email: bouwensucolick.org Oli UsherHubble/ESA, Garching, Germany Tel: +49-89-3200-6855 Email: oushereso.org Ray Villard Space Telescope Science Institute, Baltimore, USA Tel: +1-410-338-4514 Email: villardstsci.edu