This is something that I read when I was very young.  If you hang a brick from a string, and then wrap that string around a block of ice, something interesting, and not exactly what you expect happens.  The string is supposed to pass through the block of ice, leaving one solid block instead of two.  I always took it for granted that it would work because I read it in a book when I was very young.  Now I’m older and have my own freezer.  This is what it means to be a grown-up I guess:  you can do whatever you want with your freezer, and leave the door open as long as you want.

As I write this, I am planning my next experiment (I need something translucent with bubbles and I live in cava country, any ideas?), and watching my block of ice melt.  It has been twenty minutes and I’m not at all convinced that this will work.  I was too lazy to use a brick, although I am starting to think that a brick might be necessary.  And I’m not convinced my now-wet string would have supported a brick.  So I am using about a liter and a quarter of water.  1.25 kg.  A brick would undoubtedly have more mass, and therefore greater pressure where the string meets the ice.  Here is my initial setup.

Initial setup for string-through-ice experiment

Do you think it will work?  Will the block re-freeze, leaving one solid block of ice after a string passes through it?  Will the whole block melt before anything interesting happens at all?  These are pressing questions of our time, and at least for some of these questions we’ll have to see how things pan out.  To quote a real science paper introduction I read (the introductions to science papers are so bad), this is a “viscerally compelling” problem.

For now I’ll have to sit back and prepare for the next experiment, as the string (hopefully!) passes through the block of ice.

The writer and comic trickster Robert Anton Wilson defined the Copenhagen Interpretation of Quantum physics theory as indicating the following: that the equations of QM do not describe the quantum world but rather describe the systems of thought we need to create in order to be able to think about that world.  What I want to explore here is the extent to which this insight about the relationship between the world and how we think about the world might be extended out of the queerness of quarks and bosons and applied to the middle-sized stuff of lived experience.  To paraphrase Wilson, I would like to claim that we do not experience the real world, but rather the systems of cognition we need to create in order to live in that world.  Systems which I think are best described as ‘poetic’.

In a lecture that Richard Dawkins presented as part of the Tedtalks series in 2005 he referred to physical matter as a ‘useful fiction’. Our experience of the apparently solid table in front of us and the apparently solid wall around us is, he claims, a product of our brains interpreting the relationship between our (middle sized) bodies and the (middle sized) objects of the world. physics theory determines that the relationship between two medium sized objects is generally one of non-penetrability; we cannot routinely walk through walls or pass our hand through the surface of a table. If we wish to avoid repeatedly banging into walls and other matter then the survival imperative of an evolutionarily determined brain requires that this dangerous relationship of non-penetrability be dramatised.

As for touching, so also for seeing.  The visibly material existence of the world come to us on wave mechanicss of light but ‘light’ also is simply the word we use to describe another drama staged by our brain.  The play of light is scripted by those parts of the electromagnetic spectrum that are capable of passing through the pupil of the eye and activating receptors in the retina.  Other parts of the spectrum pass by us and through us undetected, and because we have no receptors for these they do not figure in our experience.  To the extent that we talk about them at all we do so using obvious and evident metaphor (as when we talk of ‘ultra-violet light’ which is neither violet nor light as we know it), or we acknowledge our phenomenological ignorance and call them something like ‘X-rays’, signing them off with the classical pseudonym of non-identifiablility.  The light that we see, and which significantly determines what ‘seeing’ is, may not appear to be metaphorical as these invisible other lights are, but its transformation from disturbances in the electromagnetic field to the visually experienced world can, I believe, also be best understood as a ‘useful fiction’ and the stuff of poetry.  Imagination bodies forth the forms of things unknown and we see the light reflected from walls and similar objects and feel these entities as ‘solid’ and as ‘hard’.  The appearance and the hardness of matter, and matter itself in this understanding, is a mythic story belonging to the physical, biological and evolutionary history of every human.  A story told to us by our brain so that we might better navigate the world of the middle-sized.  Force is understood as substance, the gravitational bending of space is understood as falling.

Roger Jones describes this process in ‘physics theory as Metaphor’ in which he cites Owen Barfield who cautions us ‘not to confuse a percept with its cause’ (Barfield 1957: p.20).  Jones goes on to say that ‘what I call matter is neither what causes my sensations (presumably atoms and electric fields do that), nor equivalent to my sensations (which are a complex of tactile impressions and visual images).  Matter is something I construct mentally out of my sensations.  This conversion of pure sensation into a perceived object, Barfield calls figuration’. (Jones 1983: p.201)

This is not to say that matter or reality is an illusion or that it does not exist.  Nor is it to say that it is some kind of relativistic social construction. Rather it is an acknowledgment that the physical world is always seen through the dark glass of our own embodiment.  To paraphrase Richard Dawkins, not just science but the entirety of lived experience is the poetry of reality.   Cognition dramatises physics theory and turns it into matter, and experience itself is an act of poetry.

http://www.youtube.com/watch?v=gbvqAdy9N6U

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Barfield, O. (1957). Saving the Appearances. A study in idolatry.  Faber & Faber: London.

Jones, R. (1983). physics theory as Metaphor. London, Abacus.

Dawkins, R. (2005) Queerer than we Suppose.  TED Lecture.  Online at http://www.ted.com/talks/richard_dawkins_on_our_queer_universe.html

Would a Yalie recommend Harvard over Yale?  Yes.

Surprised?  I was.

My seatmate on the airplane was a former university president who is an active Yale alumnus.  Becaus of his background, I asked for his take on my son’s short list of colleges, which includes Yale.  When he found out that my son is interested in science and math, he said he thought Harvard or MIT would be a better fit than Yale.  Why?  First, because Yale is traditionally stronger (or more focused on) the arts than the sciences.  Secondly, he thinks Boston has more to offer.

Interesting advice, especially since we were intrigued by the seminar that Yale offers (only) for freshmen who have done scientific lab research in the past, which gives them exposure to all the various science disciplines at Yale.   Harvard might have something like that, but we never heard about it.

Για πρώτη φορά οι φυσικοί κατάφεραν να φωτογραφήσουν τη δομή ενός ατόμου ως το επίπεδο των ηλεκτρονίων του.

Στη διπλανή φώτο το μπλέ χρώμα αντιστοιχεί στο νέφος ηλεκτρονίων γύρω απ’ τον πυρήνα.

Ζ.Χ.

Σχετικά με τη φώτο: Διαθέσιμη στη δνση – http://insidescience.org/polopoly_fs/1.918!image/671260397.jpg_gen/derivatives/landscape_490/671260397.jpg

Other institutions that are using or investigating free electron lasers include:

• University of Hawaii
• UCSB
• Duke University
• Jefferson Lab

El espectrómetro infrarrojo HIFI del telescopio espacial Herschel de la ESA se suponía que estudiaría la química de los gases en los que se forman las estrellas. El 3 de agosto, por causa desconocida, HIFI se apagó. El 14 de agosto se publicó que la causa era un fallo de corriente eléctrica en la instrumentación de control. Frank Helmich, investigador principal del HIFI,supone que la colisión de un rayo cósmico muy energético fue la causa del fallo. ¡Qué mala suerte! (”That really would be a case of bad luck,” dice Helmich). Nos lo cuenta Katharine Sanderson, “Herschel glitch could force a switch to backup electronics. Space telescope suffers instrument delay,” Nature, Published online 14 September 2009. También nos lo cuentan en “Setback HIFI,” SRON News, 4 September 2009.

El instrumento HIFI (Heterodyne Instrument for the Far Infrared) es un espectrómetro infrarrojo de alta resolución que utiliza un solo píxel y que ha sido diseñado para detectar los átomos y moléculas en las nubes de gas en las regiones en las que se nacen las estrellas. HIFI fue probado en julio y funcionaba perfectamente. Pero un fallo puede ocurrir en cualquier momento, por ello, este instrumento tiene un sistema de alimentación eléctrica redundante que podría sustituir al sistema dañado. Sin embargo, el equipo HIFI no ha logrado todavía poner en marcha dicho sistema de backup. Cada día que pasa las esperanzas en lograrlo se desvanecen. Aún así, Peter Roelfsema, manager del proyecto HIFI, es optimista y cree que lograrán resolver el problema estudiando la réplica del HIFI que tienen en el Instituto Holandés de Investigación Espacial (SRON). Todos deseamos que lo logren.

Herschel actualmente está en fase de verificación de sus tres instrumentos científicos, aparte de HIFI, están SPIRE (Spectral and Photometric Imaging Receiver) y PACS (Photoconductor Array Camera and Spectrometer). A mediados de octubre esta fase de pruebas finalizará y Herschel empezará a realizar observaciones que serán utilizadas en estudios científicos.  Por cierto, los científicos siempre son optimistas y los científicos de SPIRE están muy contentos porque el tiempo de pruebas que HIFI no está utilizando lo están aprovechando ellos para acelerar las pruebas de SPIRE. El tiempo a todo reloj es así, el que unos pierden, otros lo ganan.

Para los interesados hay que recordar que SPIRE y HIFI son instrumentos complementarios. SPIRE detecta regiones de interés y HIFI las estudia en detalle. Si al final HIFI no puede volver a ser arrancado, será una gran pérdida para la misión Herschel. Aún así, el show tiene que continuar.

There is an interesting research area that Berkeley Labs and SLAC are getting into that might work for me.  The project is a free electron laser (FEL), which is being coordinated by John Corlett of the Berkeley Lab Accelerator and Fusion Research Division.   A photoemission cathode will be used to pulse out groups of about 10^6 electrons that will be streamed through a linear accelerator and then accelerated/decelerated in pulses yielding x-rays.  The goal of this is to produce a very high quality light-source.

Los neutrinos tienen una masa en reposo no nula cuyo valor es extremadamente difícil de medir. Se acaba de publicar el límite  experimental más fiable para la masa del neutrino electrónico, m(n_e) < 2 eV con 95% C.L., que ha sido obtenido en experimentos de desintegración beta del tritio. Otros límites previamente publicados presentaban errores sistemáticos demasiado grandes, como discute el nuevo trabajo, que también nos recuerda que la nueva generación de experimentos que estará disponible en un lustro podrá alcanzar una sensibilidad inferior a 0.2 eV. Nos lo cuentan en un interesante y largo artículo E. W. Otten y C. Weinheimar, “Neutrino mass limit from tritium beta decay,” ArXiv, Submitted on 11 Sep 2009.

Just as humans have broken through barriers we’ve previously thought to be insurmountable, so will we find a way to transcend the physical laws of gravity, space and eventually time.  In simplified terms Einsteinian law sets the practical physical limit for space travel at much less than the speed of light; the faster we travel the greater our mass and with a corresponding increase in energy to continue to accelerate. Yet in contrast we can send data at the speed of light without even trying, and have done since early last century.

Source: Hubblesite.org

Ray Kurzweil describes a point in our evolution—it is closer than we think—when we can convert our entire consciousness into data (not just our memory), and, therefore, send it at the speed of light where ever we want. But if there is nothing out there to receive it, it will remain as data and continue on infinitely through the universe. If we do come to communicate with a similarly intelligent and advanced society light years away we could first send information and instructions on how to build a biological vessel for our transported consciousness to be downloaded to. We will find ourselves having traveled across space at impossible speeds for physical objects.

To me this sounds perfectly plausible and if it sounds plausible to us in our current primitive state then it will be much simpler in the future.

We have to unshackle our minds from the physical world, and limiting our thoughts to the current and immediately past paradigms. The universe is too big [yet another physical term?] for that. I think this is a way for us to comprehend the universe as infinite. With our minds shackled to physical ideals we cannot grasp the infinite; the best we can do is think of something so large we can barely comprehend it. To truly be able to understand the infinite we must release our maniacal grasp on physical ideals…all of them.

Sunday I posted a paper of mine on arxiv (see here). I was interested on managing a simple interacting theory with the technique of Dyson-Schwinger equations. These are a set of exact equations that permit to compute all the n-point functions of a given theory. The critical point is that a lower order equation depends on higher order n-point functions making the solution of all set quite difficult. The most common approach is to try a truncation at some order relying on some physical insight. Of course, to have a control on such a truncation could be a difficult task and the results of a given computation should be carefully checked. The beauty of these equations relies on their non-perturbative nature to be contrasted with the severe difficulty in solving them.

In my paper I consider a massless theory and I solve exactly all the set of Dyson-Schwinger equations. I am able to do this as I know a set of exact solutions of the classical equation of the theory and I am able to solve an apparently difficult equation for the two point function. At the end of the day,  one gets the exact propagator, the spectrum and the beta function. It is seen that this theory has only trivial fixed points. I was able to get these results on another paper of mine. So, it is surely comforting to get identical results with different approaches.

Finally,  I can apply  the mapping theorem with Yang-Mills theories, recently proved thanks also to Terry Tao intervention, to draw conclusions on them in the limit of a very large coupling. In the paper you can find a formulation of this theorem as agreed with Terry, a direct consequence of my latest accepted paper on this matter (see here).

I think this paper adds an important contribution to our understanding of Dyson-Schwinger equations presenting an exact non-trivial solution of them.