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Eine wichtige Entdeckung haben Forscher gemacht, in dem sie Proben von einem Kometen untersuchten. Die gefundenen Mineralien zeigen eindeutig, dass im Inneren des Kometen Wild2 flüssiges Wasser existiert haben muss.

Dieses Ergebnis ist sehr bedeutsam. Ein wesentlicher Punkt der Entgegnungen von Hoovers Entdeckung von Mikrofossilien in C1 Meteoriten war, dass in dem Gestein während der Reise durch das All Kammern von flüssigem Wasser existiert haben müssten, was man für unmöglich hielt. Nun ist klar, dass solche Vagabunten im All tatsächlich auch flüssiges Wasser beherbergen können.

Der Artikel in science daily hier.

Daraus:

"Current thinking suggests that it is impossible to form liquid water inside of a comet," said Dante Lauretta, an associate professor of cosmochemistry and planet formation at the UA's Lunar and Planetary Laboratory. Lauretta is the principal investigator of the UA team involved in analysis of samples returned by NASA's Stardust mission.

UA graduate student Eve Berger, who led the study, and her colleagues from Johnson Space Center and the Naval Research Laboratory made the discovery analyzing dust grains brought back to Earth from comet Wild-2 as part of the Stardust mission. Launched in 1999, the Stardust spacecraft scooped up tiny particles released from the comet's surface in 2004 and brought them back to Earth in a capsule that landed in Utah two years later.

"In our samples, we found minerals that formed in the presence of liquid water," Berger said. "At some point in its history, the comet must have harbored pockets of water."

The discovery is to be published in an upcoming online edition of the journal Geochimica et Cosmochimica Acta.

Comets are frequently called dirty snowballs because they consist of mostly water ice, peppered with rocky debris and frozen gases. Unlike asteroids, extraterrestrial chunks made up of rock and minerals, comets sport a tail -- jets of gas and vapor that the high-energy particle stream coming from the sun flushes out of their frozen bodies.

"When the ice melted on Wild-2, the resulting warm water dissolved minerals that were present at the time and precipitated the iron and copper sulfide minerals we observed in our study," Lauretta said. "The sulfide minerals formed between 50 and 200 degrees Celsius (122 and 392 degrees Fahrenheit), much warmer than the sub-zero temperatures predicted for the interior of a comet."

Discovered in 1978 by Swiss astronomer Paul Wild, Wild-2 (pronounced "Vilt") had traveled the outer reaches of the solar system for most of its 4.5 billion year history, until a close encounter with Jupiter's field of gravity sent the 3.4 mile-wide comet onto a new, highly elliptical orbit bringing it closer to the sun and the inner planets.

Scientists believe that like many other comets, Wild-2 originated in the Kuiper belt, a region extending from beyond Neptune's orbit into deep space, containing icy debris left over from the formation of the solar system. Wild-2 is thought to have spent most of its time in the Kuiper belt, transiting on unstable orbits within the planetary system before Jupiter's gravity hurled it into the neighborhood of the sun.

The discovery of the low-temperature sulfide minerals is important for our understanding of how comets formed -- which in turn tells us about the origin of the solar system.

In addition to providing evidence of liquid water, the discovered ingredients put an upper limit to the temperatures Wild-2 encountered during its origin and history.

"The mineral we found -- cubanite -- is very rare in sample collections from space," Berger said. "It comes in two forms -- the one we found only exists below 210 degrees Celsius (99 degrees Fahrenheit). This is exciting because it tells us those grains have not seen temperatures higher than that. "

Cubanite is a copper iron sulfide, which is also found in ore deposits on Earth exposed to heated groundwater and in a particular type of meteorite.

"Wherever the cubanite formed, it stayed cool," she added. "If this mineral formed on the comet, it has implications for heat sources on comets in general."

According to Berger, two ways to generate heat sources on comets are minor collisions with other objects and radioactive decay of elements present in the comet's mixture.

Heat generated at the site of minor impacts might generate pockets of water in which the sulfides could form very quickly, within about a year (as opposed to millions of years). This could happen at any point in the comet's history. Radioactive decay on the other hand, would point to a very early formation of the minerals since the radioactive nuclides would decay over time and cause the heat source to flicker out.

The presence of the cubanite and the other sulfide minerals helps scientists better understand cometary heat sources. The interior of the comet must have been warm enough to melt ice yet cool enough -- below 210 degrees Celsius -- to form cubanite.

"Such detailed thermal constraints will allow for detailed analysis of the role temperature played during the history of comet Wild 2," Lauretta said.

Each sample Berger's team analyzed consisted of a microscopic speck of cometary dust about the size of a bacterial cell. The group then studied the chemical composition by electron microscopy and X-ray analysis, during which the chemical elements revealed their presence by giving off a characteristic beam. Turning the sample in different orientations gave the scientists clues about its crystallographic structure.

According to Lauretta, the findings show that comets experienced processes such as heating and chemical reactions in liquid water that changed the minerals they inherited from the time when the solar system was still a protoplanetary disk, a swirling mix of hot gases and dust, before it cooled down enough for planets to form.

The results demonstrate the increasingly apparent connections between comets and asteroids.

"What we found makes us look at comets in a different way," Lauretta said. "We think they should be viewed as individual entities with their own unique geologic history."

"This study shows the high science value of sample return missions," Lauretta said. "These grains would never been detected by remote sensing or by flying a spacecraft past the comet to make observations without collecting a sample."

Einen neuen Weltrekord mit einem Register aus verschränkten Quantenbits haben Forscher aufgestellt, wie scinexx berichtet: hier.

Zitat:

Weltrekord: 14 Quantenbits
Die Physiker um Blatt halten seit 2005 den Rekord für die Anzahl von verschränkten Quantenbits, die in einem Experiment realisiert wurden. Bis heute ist es niemand anderem gelungen, acht Teilchen auf kontrollierte Art und Weise zu verschränken und damit ein „Quantenbyte“ zu erzeugen.

Nun haben die Innsbrucker Wissenschaftler diesen Rekord noch einmal beinahe verdoppelt. In einer Ionenfalle haben sie 14 Kalziumatome gefangen, die sie, einem Quantenprozessor gleich, mit Laserlicht manipulieren. Interne Zustände jedes Atoms bilden dabei einzelne Quantenbits, zusammen entsteht ein Quantenregister mit 14 Recheneinheiten. Dieses bildet das Herzstück eines zukünftigen Quantencomputers.

Die Innsbrucker Physiker stellten aber auch fest, dass bei ihnen die Störungsempfindlichkeit nicht wie meist angenommen linear sondern mit der Anzahl der Teilchen quadratisch zunimmt. Werden mehrere Teilchen verschränkt, steigt die Empfindlichkeit deshalb stark an. „Dies wird als Superdekohärenz bezeichnet“, sagt Monz. „In der Quanteninformation wurde dieses Phänomen bisher kaum wahrgenommen.“ Es hat nicht nur für den Bau von Quantencomputern Bedeutung, sondern auch bei der Konstruktion sehr genauer Atomuhren oder für Quantensimulationen.

Davon berichtet zumindest science daily: hier.

Zitat:

Before the publication of this paper, scientists and engineers had five different types of symmetries to use as tools for understanding the structures of materials whose building blocks are arranged in fairly regular patterns. Four types of symmetries had been known for thousands of years -- called rotation, inversion, rotation inversion, and translation -- and a fifth type -- called time reversal -- had been discovered about 60 years ago. Now, Gopalan and Litvin have added a new, sixth, type, called rotation reversal. As a result, the number of known ways in which the components of such crystalline materials can be combined in symmetrical ways has multiplied from no more than 1,651 before to more than 17,800 now. "We mathematically combined the new rotation-reversal symmetry with the previous five symmetries and now we know that symmetrical groups can form in crystalline materials in a much larger number of ways," said Daniel B. Litvin, distinguished professor of physics, who coauthored the study with Venkatraman Gopalan, professor of materials science and engineering.

The new rotation-reversal symmetry enriches the mathematical language that researchers use to describe a crystalline material's structure and to predict its properties. "Rotation reversal is an absolutely new approach that is different in that it acts on a static component of the material's structure, not on the whole structure all at once," Litvin said. "It is important to look at symmetries in materials because symmetry dictates all natural laws in our physical universe."

The most simple type of symmetry -- rotation symmetry -- is obvious, for example, when a square shape is rotated around its center point: the square shows its symmetrical character by looking exactly the same at four points during the rotation: at 90 degrees, 180 degrees, 270 degrees, and 360 degrees. Gopalan and Litvin say their new rotation-reversal symmetry is obvious, as well, if you know where to look.

The "eureka moment" of the discovery occurred when Gopalan recognized that the simple concept of reversing the direction of a spiral-shaped structure from clockwise to counterclockwise opens the door to a distinctly new type of symmetry. Just as a square shape has the quality of rotation symmetry even when it is not being rotated, Gopalan realized that a spiral shape has the quality of rotation-reversal symmetry even when it is not being physically forced to rotate in the reverse direction. Their further work with this rotation-reversal concept revealed many more structural symmetries than previously had been recognized in materials containing various types of directionally oriented structures. Many important biological molecules, for example, are said to be either "right handed" or "left handed," including DNA, sugars, and proteins.

"We found that rotation-reversal symmetry also exists in paired structures where the partner components lean toward each other, then away from each other in paired patterns symmetrically throughout a material," Gopalan said. These "tilting octahedral" structures are common in a wide variety of crystalline materials, where all the component structures are tightly interconnected by networks of shared atoms. The researchers say it is possible that components of materials with rotation-reversal symmetry could be engineered to function as on/off switches for a variety of novel applications.

The now-much-larger number of possible symmetry groups also is expected to be useful in identifying materials with unusual combinations of properties. "For example, the goal in developing a ferroelectric ferromagnet is to have a material in which the electrical dipoles and the magnetic moments coexist and are coupled in the same material -- that is, a material that allows electrical control of magnetism -- which would be very useful to have in computers," Gopalan said. The addition of rotation-reversal symmetry to the materials-science toolbox may help researchers to identify and search for structures in materials that could have strong ferroelectric and ferromagnetic properties.

Am 31.März beendete ich die Lektüre des neuen Papstbuches zu Jesus von Nazareth - Band II -. Darin macht Benedikt XVI. eine sensationelle Aussage, die sich genau mit dem beschäftigt und stützt, was auch Michael König in seinem Urwort - Buch herausstellt.

Damit dies niemand für einen Aprilscherz hält, habe ich bis heute mit meiner Vorankündigung gewartet:

Ich werde demnächst im Blog 'Evolution und Schöpfung' ausführlich auf diese Passage eingehen und deren wissenschaftliche Bedeutung im Lichte der Urwort - Theorie erörtern.

Dazu braucht es aber eine gewisse Zeit, daher heute nur ersteinmal diese Vorwarnung.

Übrigens hat m.W. bis heute diese gefundene Passage noch niemand herausgestellt. Ich denke, um ihren sensationellen Gehalt erkennen zu können, muss man Michael Königs Buch verinnerlicht haben. Leider scheint es mir so, dass die Schnittmenge der Leser von König und der Leser vom neuen Papstbuch recht gering ist. Später mehr dazu: Stay tuned...!

Eine der Hauptlehrsätze der darwinschen Evolution ist jener vom Überleben der Bestangepassten in einer gegebenen Umgebung. In 'Nature' wurde nun ein Artikel veröffentlicht, dass diese Behauptung eindrücklich anhand von Bakterienkulturen zu widerlegen in der Lage ist: Evolution: Not Only the Fittest Survive

Zitat:

Conventional wisdom has it that for any given niche there should be a best species, the fittest, that will eventually dominate to exclude all others.

This is the principle of survival of the fittest. Ecologists often call this idea the `competitive exclusion principle' and it predicts that complex environments are needed to support complex, diverse populations.

Professor Robert Beardmore, from the University of Exeter, said: "Microbiologists have tested this principle by constructing very simple environments in the lab to see what happens after hundreds of generations of bacterial evolution, about 3,000 years in human terms. It had been believed that the genome of only the fittest bacteria would be left, but that wasn't their finding. The experiments generated lots of unexpected genetic diversity."

This test tube biodiversity proved controversial when first observed and had been explained away with claims that insufficient time had been allowed to pass for a clear winner to emerge.

The new research shows the experiments were not anomalies.

Professor Laurence Hurst, of the University of Bath, said: "Key to the new understanding is the realization that the amount of energy organisms squeeze out of their food depends on how much food they have. Give them abundant food and they use it inefficiently. When we combine this with the notion that organisms with different food-utilizing strategies are also affected in different ways by genetic mutations, then we discover a new principle, one in which both the fit and the unfit coexist indefinitely."

Dr Ivana Gudelj, also from the University of Exeter, said: "The fit use food well but they aren't resilient to mutations, whereas the less efficient, unfit consumers are maintained by their resilience to mutation. If there's a low mutation rate, survival of the fittest rules, but if not, lots of diversity can be maintained.

"Rather nicely, the numbers needed for the principle to work accord with those enigmatic experiments on bacteria. Their mutation rate seems to be high enough for both fit and unfit to be maintained."

Nein, um eine neue Ankündigung für einen Beweis der Riemann-Vermutung kann ich nicht liefern, aber eine interessante Meldung zeigt eine neue Art dieses Problem anzugehen.

Die Meldung hier.