Un trou noir surpris dans un homicide stellaire

                                             Photo NASA

Des chercheurs utilisant le telescope GALEX de NASA et l'observatoire Pan-STARRS a Hawaii decouvrirent la rupture d'une etoile par un supermassif trou noir. Cette etoile passait trop proche du trou noir. Ils utiliserent les donnees de Chandra pour ecarter la theorie d'un noyau actif galactique. La galaxie ou cet acte violent survint s'appelle PS1-10jh et est localisee a 2.7 billions d'annees-lumiere de la Terre.

L'image simulee a l'aide d'un computer montre l'eruption de gaz d'une etoile demantelee par des raz-de-marees de forces tandis qu'elle est absorbee par le trou noir. Une partie du gaz est aussi ejectee a grande vitesse dans l'espace.

.Utilisant des observations de telescopes dans l'espace et sur le terrain lea astronautes ont obtenu l'evidence la plus directe de ce violent processus: un supermassif trou noir detruisant une etoile qui voyageait trop pres. L'appareil orbitant GALEX de NASA et le telescope Pan-STARRS1 sur le sommet de Haleakala a Hawaii etaient utilises pour aider a identifier les restes de l'etoile.  
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Une fusee eclairante ultraviolette et de la lumiere optique montraient du gas tombant dans le trou noir aussi bien que du gaz riche en helium s'evacuant du systeme. Lors du demantelement de l'etoile une partie tombe dans le trou noir tandis que le reste se desagrege a grandes vitesses. La fusee eclairante et ses proprietes permettent une demonstration de ce scenario et fournissent des details inconnus a propos de la victime stellaire. 

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Pour ecarter la possibilite d'un noyau actif s'eclairant dans la galaxie au lieu de la destruction d'une etoile, l'equipe utilisait l'observatoire a rayons X Chandra de NASA pour etudier le gaz chaud. Chandrs montrait que les caracteristiques du gaz ne correspondaient pas a celles d'un noyau actif galactique.

La galaxie ou le supermassif trou noir detruisit l'etoile passante est connue comme etant PS1-10jh et est localisee a environ 2.7 billions d'annees-lumiere de la terre. Les astronautes estiment que le trou noir dans PS1-10jh a une masse de plusieurs millions de soleils, ce qui est comparable au supermassif trou noir de la voie lactee, notre propre galaxie.

 http://chandra.harvard.edu/photo/2012/ps1/

The illusion of space

It seems that one can put as much as stuff in any container as soon as the content is compressed. We tend to think that there is no limit in the amount that space can take. The space gives the illusion of an hologram. However scientists demonstrated that there is a limit. This principle explains the formation of black holes in the universe.

My dad took a peculiar pleasure in fitting the maximum amount of stuff into the smallest possible space. Whenever we went on a family trip, he packed our suitcases like a 3-D jigsaw puzzle, ensuring there wasn’t a single wasted inch—a laudable skill as far as I was concerned, since I could take all the toys I wanted and he’d find room for them. (The bags weighed a ton, but those were the days of free baggage check.) Later, when I drove off to my first apartment, he managed to get a household’s worth of stuff into a two-door car. He always denied there’s any limit on how much stuff you can pack into a certain volume. It was just a question of ingenuity. Alas, the theoretical physicists speaking at A Thin Sheet of Reality: The Universe as a Hologram at this year’s World Science Festival have bad news: there is a limit. If you exceed it, the gravitational force exerted by the contents of your suitcase will become so intense that the suitcase collapses into a black hole, and you’ll never see your stuff again. Admittedly, this ultimate limit is pretty forgiving. An airplane roll-on could hold a Jupiter’s worth of highly compressed material before you ran into trouble with black holes. (The TSA is another matter.) A limit, per se, might not seem terribly surprising. No amount of paternal ingenuity can overcome the fact that material objects unavoidably take up space; however hard you squeeze, you can’t compress them to nothing. But what’s strange about the ultimate packing limit is that it depends on the size of the container. Bigger containers can hold proportionately less stuff than smaller ones. A two-door car, as wide as two suitcases, has room for eight suitcases in all. If I pack each suitcase to its ultimate limit and then jam them all into the car, I will exceed the car’s overall limit and lose the lot. The most I can put in is two. The car promises so much extra room, but as soon as I try to avail myself of it, nature stops me. It is as if the space is a mirage. This limit on packing is one aspect of what physicists call the Holographic Principle by analogy to a hologram, which, like my old car, gives the illusion of depth. What happens when you pack things together is one of the most important thought experiments for physicists today. When I dropped by Stanford University in February to chat with one of the participants in this festival event, Lenny Susskind, he told me, "I think it’s the most radical lesson that we’ve learned about physics since the Uncertainty Principle." What makes it so radical is that the density of matter was supposed to depend only on how compressed each individual scrap of matter can become. It shouldn’t make any difference how many scraps you pile up. That is true not just of density but of other key properties such as how much information each scrap of material can encode. The whole is just the sum of its parts. This intuition is formalized in the modern theory of matter, known as quantum field theory. But the propensity to form black holes means that what one scrap of matter is capable of doing depends on what all the other scraps are doing. The whole is less than the sum of its parts. Physicists have suspected for over half a century that quantum field theory needs to give way on extremely small scales, eventually becoming unified with the other great pillar of modern physics, Einstein’s general theory of relativity. That is why they have built giant particle accelerators, which act as powerful microscopes to zoom in on the sub-subatomic world. But the Holographic Principle means that quantum field theory also breaks down on large scales. Whereas no suitcase on Earth is at risk of collapsing to a black hole, the limit become pressing as size increases. Objects with the dimensions of the solar system max out at the density of liquid water. The cosmos is filled with black holes that formed when natural processes attempted to pack too much material too tightly. It’s one thing to expect a breakdown of quantum field theory on small scales, quite another to make sense of it on a large scale. The Holographic Principle also shows that space isn’t what it appears to be. I don’t mean outer space, the realm of astronauts and asteroids, but the space all around us, the space in our suitcases and cars, the space that separates lovers when they part. Space is pulling a bait-and-switch on us: it seems to have plenty of room to hold stuff, yet it doesn’t. The Holographic Principle is one of several clues suggesting that the concept of “space” is an elaborate illusion—or, to be more precise, that it emerges from a deeper spaceless reality, much as living organisms emerge from inanimate matter. What breathes life into a lifeless jumble of chemicals is the way those pieces fit together and work together. Likewise, the world may develop a spatial structure from the way its most fundamental ingredients fit together and work together. The best-developed theory for how this can happen goes by the somewhat technical name of “gravity/gauge duality,” which uses the concepts of quantum field theory to do the fitting and working. The force of gravity turns out to be a by-product of the process. One implication is that spatial notions such as distance are derivative. Objects that appear to be far apart may actually be lying right on top of each other, when considered in some deeper sense—which perhaps offers some consolation to the separated lovers of the world. This panel brings together Susskind and the other father of the Holographic Principle, Nobel laureate Gerard ’t Hooft, along with two physicists who generalized and elaborated on their work, Raphael Bousso and Herman Verlinde.

http://blogs.scientificamerican.com/observations/2011/05/17/space-is-an-elaborate-illusion/

What would be the implications of the use of the world's biggest human brain map in the cure of diseases?

This scientific breakthrough in the study of the human brain is important in the prevention and cure of diseases because of the high percentage of genes found in the human brain. It is then assumed that any deficient organ of the body would  refer the study of its deficiency to the analysis of the genes of the brain . This may facilitate other studies of the cure of diseases by growing new cells in the deficient organ and not using medication.  A genetic analysis can also help the prevention of disease. Can some incurable diseases like Alzheimer, cancers, etc  be definitely treated.?. If such high percentage of genes is found in the human brain the latter is then the orchestra chief of all the parts of the human body. Another assumption would be that if the brain is healthy the rest of the body would be so. If this assumption is true and if the brain is the home of the mind the psychosomatic nature of illnesses or diseases is corroborated. Mindfully speaking a positive outlook of life influences one's overall health including that of the body.

Yves Simon, Educator

World's biggest human brain map unveiled

Hayley Crawford, reporter
(Images: Allen Institute for Brain Science)
The world's biggest computerised map of the brain was released yesterday by scientists at the Allen Institute for Brain Science, in Seattle, Washington, after more than four years of cutting-edge research.
The Human Brain Atlas is an interactive research tool that will help scientists to understand how the brain works and aid new discoveries in disease and treatments.
The information used to build it comes from the analysis of two human brains, using magnetic resonance imaging (MRI) and a variation of MRI called diffusion tensor imaging.
Allan Jones, the CEO of the institute, told Wired how the brains were also chopped up into small pieces, and RNA extracted from the tissue. They used this RNA to obtain a read-out of the 25,000 genes in the human genome.
All this information was put together to create a detailed map of the brain. One thousand anatomical sites in the brain can be searched, supported by more than 100 million data points that indicate the gene expression and biochemistry of each site.
For example, a researcher could quickly create a 3D snapshot (see image below) of all the locations in the brain where Prozac's biochemical targets are expressed.
  The researchers found a striking 94 per cent similarity in the biochemistry between the two brains, and     discovered that at least 82 per cent of all human genes are expressed in the brain.
Allan says this isn't too surprising: When you think about the complexity of the functions of the brain, and the variety of different cell types found within the brain, it's not quite as surprising to see how much of the genome is used to serve the brain
Both brains used in the $55 million project were male, which prompted The Wall Street Journal to ask why a woman's brain had not been included. Allan told Bloomberg that eligible brain donors usually die from accidental causes or cardiac arrest, both of which disproportionately affect men. However, he says the project is currently processing a female brain, and that ultimately, the facility will run at least 10 brains through the process.
Other researchers are also attempting to map neural connections in a mouse brain, something MRI cannot do. They will turn slices of brain into digital images by an automated electron microscope. A computer will read those images, trace the outlines of nerve cells, and stack the pictures into a 3D reconstruction. Maps like these have limitless potential in drug discovery and human genetics and will no doubt be an essential step forward in the fight against disease.