The research aims to produce valid information and must use reliable instruments that guarantee accurate and make it quantifiable and possible reproducibility. Allowing the exclusion or at least control prejudice of personal insights and trends that may distort the results.
jueves, 26 de mayo de 2011
Does Quantum Theory Explain Consciousness?
Consciousness: How do you go about explaining that? Indeed, many scientists are currently studying what happens in the brain and how the mind relates to the outside world, but quantifying what gives us consciousness is proving to be a rather tough nut to crack.
Is there some supernatural influence? Is it purely biological? Or is there something else, something more... physicsy?
In a fascinating column for New Statesman, writer Michael Brooks touches on this tricky subject, and it reminded me of a conversation I had with a friend not so long ago.
"Don't you think our consciousness might be explained by the Large Hadron Collider?" my friend asked. (Full disclosure: There was gin and tonic involved, so this wasn't an everyday discussion.)
"What do you mean?" I asked in reply.
"Well, the LHC is probing states of matter that existed immediately after the Big Bang, so it's bound to throw up some new physics -- don't you reckon it might uncover some sort of particle, or energy, that might explain our connectivity with the Universe?"
(By "energy," she wasn't referring to energy in the physical sense, she was playfully baiting me with New Age philosophy.)
Possibly inspired by the crazy science butchered in the TV series FlashForward -- in which everyone on the planet gets knocked out for 2 minutes and 17 seconds, having visions 6 months into the future, after an experiment apparently went awry in a particle accelerator -- my friend was quick to point out that quantum physics, by its nature, is weird, and consciousness is, well, weird, so there must be some connection.
While this may be attractive -- after all, quantum mechanics brought us Schrodinger's-very-confused-dead-or-alive-(or both)-Cat -- there is a fundamental flaw in this logic. And as Brooks mentions in his article, "strange quantum effects don't fit in with our everyday experience of the world, they have been invoked to resolve myriad things we don't yet understand, such as supernatural phenomena."
Although consciousness is not a supernatural phenomenon, science has yet to explain it. In this world of high technology, where we seem to have an answer for everything, it seems odd that we don't yet have an answer for what makes us, us. Why shouldn't quantum theory explain consciousness?
Brooks mentions Deepak Chopra's book "Quantum Healing," in which Chopra jumped to the conclusion that quantum entanglement links everything in the Universe, and therefore it must create consciousness. However, even respected scientists aren't immune to the pull of the mystery of quantum mechanics.
Roger Penrose, famous British physicist, recently argued "that we will need to invoke 'new physics and exotic biological structures': rewriting quantum theory to make sense of consciousness," Brooks writes.
Although Brooks calls Penrose's point of view "disappointing," I don't find it surprising as this is the same physicist that saw odd patterns in the cosmic microwave background radiation and jumped to the conclusion that it must be a gravitational wave signal from a previous universe. In the end, Penrose was making shapes out of random noise -- akin to imagining bunny shapes in the clouds.
So why is there this apparent connection between consciousness and quantum theory? Brooks calls it the "conservation of mysteries," where you have two separate mysteries, but for some reason, we think there must be causation (i.e. one mystery causes the other).
This is along the same lines as the logical fallacy cum hoc ergo propter hoc ("with this, therefore because of this") and it applies to a whole host of scientific (and pseudo-scientific) reasoning. Just because quantum theory acts mysteriously, it doesn't mean quantum theory explains the mystery of consciousness.
Of course, quantum theory might explain consciousness, but that can only be proved or disproved through scientific method rather than by simply making stuff up.
Publicado por Nathaniel en 10:59 No hay comentarios:
Pyramid-Exploring Robot Reveals Hidden Hieroglyphs
A robot was sent through the Great Pyramid of Giza and transmitted images showing hieroglyphs behind a mysterious door.
Archaeologists hope the symbols might help them understand the purpose of shafts built within the pyramids.
The Great Pyramid has long been rumored to have hidden passageways leading to secret chambers.
A composite of images of the floor of the Great Pyramid is shown. Red hieroglyphs are visible. Click to enlarge this image.
A robot explorer sent through the Great Pyramid of Giza has begun to unveil some of the secrets behind the 4,500-year-old pharaonic mausoleum as it transmitted the first images behind one of its mysterious doors.
The images revealed hieroglyphs written in red paint that have not been seen by human eyes since the construction of the pyramid. The pictures also unveiled new details about two puzzling copper pins embedded in one of the so called "secret doors."
Published in the Annales du Service Des Antiquities de l'Egypte (ASAE), the images of markings and graffiti could unlock the secrets of the monument's puzzling architecture.
"We believe that if these hieroglyphs could be deciphered they could help Egyptologists work out why these mysterious shafts were built," Rob Richardson, the engineer who designed the robot at the University of Leeds, said.
Built for the pharaoh Cheops, also known as Khufu, the Great Pyramid is the last remaining wonder of the ancient world.
The monument is the largest of a family of three pyramids on the Giza plateau, on the outskirts of Cairo, and has long been rumored to have hidden passageways leading to secret chambers.
Archaeologists have long puzzled over the purpose of four narrow shafts deep inside the pyramid since they were first discovered in 1872.
Two shafts, extend from the upper, or "Kings Chamber" exit into open air. But the lower two, one on the south side and one on the north side in the so-called "Queen's Chamber" disappear within the structures, deepening the pyramid mystery.
Widely believed to be ritual passageways for the dead pharaoh's soul to reach the afterlife, these 8-inch-square shafts remained unexplored until 1993, when German engineer Rudolf Gantenbrink sent a robot through the southern shaft.
After a steady climb of 213 feet from the heart of the pyramid, the robot came to a stop in front of a mysterious limestone slab adorned with two copper pins.
Nine years later, Hawass explored the southern shaft on live television. As the world held its breath, a tomb-raiding robot pushed a camera through a hole drilled in the copper pinned door -- only to reveal what appeared to be another door.
The following day, Hawass sent the robot through the northern shaft.
After crawling for 213 feet and navigating several sharp bends, the robot came to an abrupt halt in front of another limestone slab.
As with the Gantenbrink door, the stone was adorned with two copper pins.
"I dedicated my whole life to study the secrets of the Great Pyramid. My goal is to finally find out what’s behind these secret doors," Zahi Hawass, Egypt's Minister of State for Antiquities Affairs, told Discovery News in a recent interview.
In the attempt to solve the mystery, Hawass established the Djedi project, a joint international-Egyptian mission, which he named after the magician who Khufu consulted when planning the layout of this pyramid.
"I selected the Djedi team during a competition that I coordinated to pick the best possible robot to explore the shafts in the Great Pyramid," Hawass said.
The winning robot, designed by Leeds University, has indeed gone further than anyone has ever been before in the pyramid.
The project began with the exploration of the southern shaft, which ends at the so called "Gantenbrink’s door."
The robot was able to climb inside the walls of the shaft while carrying a "micro snake" camera that can see around corners.
Unlike previous expeditions, in which camera images were only taken looking straight ahead, the bendy camera was small enough to fit through a small hole in a stone "door," giving researchers a clear view into the chamber beyond. It was at that time that the camera sent back images of 4,500-year-old markings.
"There are many unanswered questions that these images raise," Richardson told Discovery News. "Why is there writing in this space? What does the writing say? There appears to be a masonry cutting mark next to the figures: why was it not cut along this line?" Roberston wondered.
The researchers were also able to scrutinize the two famous copper pins embedded in the door to the chamber that had only ever been glimpsed from the front before.
"The back of the pins curve back on themselves. Why? What was the purpose of these pins? The loops seem too small to serve a mechanical purpose," Richardson said.
The new information dismisses the hypothesis that the copper pins were handles, and might point to an ornamental purpose.
"Also, the back of the door is polished so it must have been important. It doesn't look like it was a rough piece of stone used to stop debris getting into the shaft," project mission manager Shaun Whitehead, of the exploration company Scoutek UK, said.
The Djedi robot is expected to reveal much more in the next months.
The device is equipped with a unique range of tools which include a miniature "beetle" robot that can fit through a 19 mm diameter hole, a coring drill, and a miniaturized ultrasonic device that can tap on walls and listen to the response to help determine the thickness of the stone.
The next step will be an investigation of the chamber's far wall to check whether it is another door, as suggested in the 2002 live exploration, or a solid block of stone.
"Then we are going to explore the northern shaft," Richardson said.
The team has committed to completing the work by the end of 2011. A detailed report on the findings is expected to be published in early 2012.
Publicado por Nathaniel en 10:57 No hay comentarios:
Tushka, Oklahoma tornado USA 2011
Publicado por Nathaniel en 10:55 No hay comentarios:
Densest Matter Created in Big-Bang Machine
A superhot substance recently made in the Large Hadron Collider (pictures) is the densest form of matter ever observed, scientists announced this week.
Known as a quark-gluon plasma, the primordial state of matter may be what the entire universe was like in the immediate aftermath of the big bang.
The exotic material is more than a hundred thousand times hotter than the inside of the sun and is denser than a neutron star, one of the densest known objects in the universe.
"Besides black holes, there's nothing denser than what we're creating," said David Evans, a physicist at the University of Birmingham in the U.K. and a team leader for the LHC's ALICE detector, which helped observe the quark-gluon plasma.
"If you had a cubic centimeter of this stuff, it would weigh 40 billion tons."
Densest Matter Acts Like Perfect Liquid
By triggering hundreds of thousands of high-speed collisions each second, physicists using the LHC hope to break subatomic particles into even more basic forms of matter, which can be used to study what the universe was like a trillionth of a second after the big bang.
LHC scientists made the quark-gluon plasma last year by smashing together lead ions—lead atoms that have been stripped of their electrons—at nearly the speed of light.
As the name suggests, quark-gluon plasma is made up of quarks and gluons. Quarks are the elementary building blocks of positively charged protons and neutral neutrons, which make up atomic cores. Gluons are particles that "glue" quarks together using the so-called strong force.
It's thought that, as the universe cooled, the quark-gluon plasma that existed after the big bang coalesced to form matter as we know it today.
The quark-gluon plasma created at the LHC is about twice the amount and about twice as hot as quark-gluon plasma previously made using the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, New York.
Still, the plasmas created by the two machines are very similar, scientists said this week during the Quark Matter 2011 Conference in Annecy, France. For example, scientists have now confirmed that both versions behaved like so-called perfect liquids, with nearly zero friction.
"If you stir a cup of tea with a spoon and then take the spoon out, the tea stirs for a while and then it stops. If you had a perfect liquid and you stirred it, it would carry on going around forever," Evans explained.
Some theories predict that, in the extreme heat of the very early universe, quarks and gluons would have been even more widely spaced, creating a quark-gluon plasma that behaved like a gas. The ALICE team is therefore looking for evidence of gas-like behavior in the early stages of their quark-gluon plasma formation.
"There are slight differences between our measurement and RHIC's," Evans said.
"It could well be that in the very early stages [of our quark-gluon plasma], it's behaving more like a gas, and then as it cools it turns into a liquid, but we will need to investigate this further."
Highs and Lows of Making Matter
If this gas-to-liquid transition has indeed been observed, it would be surprising, since theory predicts that it should occur at much higher temperatures than those currently being produced at the LHC, said Thomas Ludlam, chair of the physics department at Brookhaven.
"I would regard the ALICE claim that they may be seeing hints of this as very interesting, but rather speculative at this stage," said Ludlam, who was not involved in the project.
The results are nevertheless very exciting, he added. "They show that the LHC"—which went online in 2009 after more than a year's delay due to mechanical problems—"is squarely in the game now."
Also, by comparing the lower energy quark-gluon plasma created at the RHIC with the higher energy version from the LHC, scientists could gain a better understanding of how and when the substance changed as the universe cooled, Ludlam said.
"I think we're now at a point where, with these two machines, we can look over a very wide energy range at the properties of the quark-gluon plasma as it evolves with temperature and density," Ludlam said.
With this goal in mind, he added, RHIC scientists have been trying for the past year to create a quark-gluon plasma at even lower energies, to find the temperature at which quarks and gluons come together to form protons and neutrons.
Meanwhile, the LHC is still operating at only half of its maximum energy, and the ALICE team expects to create even denser forms of quark-gluon plasma as the machine ramps up in the future.
Publicado por Nathaniel en 10:51 No hay comentarios:
Previous post Next post Electrons Are Near-Perfect Spheres
A 10-year study has revealed that the electron is very spherical indeed.
To be precise, the electron differs from being perfectly round by less than 0.000000000000000000000000001 cm. To put that in context; if an electron was the size of the solar system, it would be out from being perfectly round by less than the width of a human hair.
The Imperial College team behind the research, which was conducted on molecules of ytterbium flouride, used a laser to make measurements of the motion of electrons, and in particular the wobble they exhibit when spinning. They observed no such wobble, implying that the electron is perfectly round at the levels of precision available, reflected in the figure above.
The co-author of the report describing the research, Jony Hudson, said: “We’re really pleased that we’ve been able to improve our knowledge of one of the basic building blocks of matter. It’s been a very difficult measurement to make, but this knowledge will let us improve our theories of fundamental physics. People are often surprised to hear that our theories of physics aren’t ‘finished’, but in truth they get constantly refined and improved by making ever more accurate measurements like this one.”
The next step is to up that precision level even further, using new methods to cool the molecules to extremely low temperatures and control their motion. The results are important in the study of antimatter, and particularly the positron — which should behave identically to the electron but with an opposite electrical charge. If more differences can be found, it could help to explain why far less antimatter has been discovered in the universe than predicted by theory.
Publicado por Nathaniel en 10:47 No hay comentarios:
Discovering A New Earth 430 Light Years Away Astronomers Spy Earth-like Planet Forming Around Distant Star
Astrophysicists analyzing infrared images captured by the Spitzer Space Telescope found indications of a dust cloud surrounding a relatively young star. The star is 10 to 16 million years old, and analysis of the dust cloud suggests that it may coalesce and become a rocky planet like earth. It is located at a distance from the star that it may build an atmosphere, collect liquid water, and perhaps, in millions and millions of years, support life.
It took billions of years and the perfect conditions for our Earth to grow and form. Now, those same conditions can be seen in space, shaping a similar planet. Ivanhoe explains this exciting space discovery.
Far, far away, something amazing is brewing in space. Swirling around a giant star similar to our sun, astrophysicists have spotted the very early stages of a planet taking shape.
"What we think we're seeing is the actual formation of a planet -- terrestrial planet -- a rocky planet like the Earth, around the star," Carey Lisse, Ph.D., a senior research scientist at Johns Hopkins Applied Physics Laboratory in Laurel, Md., told Ivanhoe.
The Earth-like planet is about 430 light years away or 2.5x1015 miles from Earth. It's inside a huge dust belt -- bigger than our asteroid belt -- with enough dusty material to build a planet. "The material is forming at just the same distance, or close to the same distance where the Earth formed from the sun," Dr. Lisse says.
To find the planet, astronomers used images captured by the Spitzer Space Telescope. It looks for infrared light or heat radiating from the dusty materials. The images also confirm the rocky fragments forming the new planet are similar to materials found in the Earth's crust and core.
"So, the body that's going to form -- the planet that's going to form -- isn't going to be this gas giant with incredibly thick atmosphere," explains Dr. Lisse. It's going to be a rocky planet like Mars or Venus or the Earth."
There's also an outer ice belt circling the young planet, making it more likely that water could reach the new planet's surface … and maybe even life; but don't wait around for signs of life. The planet still needs another 100 million years before it's completely formed.
Astronomers say the star the new planet is spinning around is between ten and 16 million years old, which is the perfect age for forming Earth-like planets.
ABOUT THE SPITZER TELESCOPE: The Spitzer Space Telescope was launched on 25 August 2003. Spitzer detects the infrared energy radiated by objects in space. Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground. Spitzer allows us to peer into regions of space that are hidden from optical telescopes.
Many areas of space are filled with vast, dense clouds of gas and dust that block our view. Infrared light, however can penetrate these clouds, allowing us to peer into regions of star formation, the centers of galaxies, and into newly forming planetary systems. Infrared also brings us information about the cooler objects in space, such as smaller stars which are too dim to be detected by their visible light, extrasolar planets, and giant molecular clouds. Also, many molecules in space, including organic molecules, have their unique signatures in the infrared.
WHAT IS INFRARED LIGHT? Infrared radiation is an invisible form of light that we usually detect as heat, like the sun shining on our face, or the warmth of a campfire. It has all the same properties as visible light: for example, it can be focused and reflected. The only difference is that it has a longer wavelength, which means we can't see it with the naked eye. Light is made of tiny particles called photons, and the wavelength tells us how fast those particles are vibrating. The shorter the wavelength, the faster the particles are moving. Shorter light waves look blue, and longer ones look red.
The wavelength of infrared light is so long that we can't see it at all. Any warm object gives off infrared radiation. By checking in the infrared spectrum, engineers can find heat leaks in buildings, doctors can find hidden tumors in the body, and biologists can locate diseased plants in a forest. Astronomers use infrared imaging to detect warm dust around new stars that are not yet "hot" enough to emit visible light.
The American Astronomical Society and the American Geophysical Union contributed to the information contained in the video portion of this report.
Publicado por Nathaniel en 10:42 No hay comentarios:
Brilliant but Solitary Superstar Discovered in Nearby Galaxy
An international team of astronomers  has used ESO's Very Large Telescope to carefully study the star VFTS 682  in the Large Magellanic Cloud, a small neighbouring galaxy to the Milky Way. By analysing the star's light, using the FLAMES instrument on the VLT, they have found that it is about 150 times the mass of the Sun. Stars like these have so far only been found in the crowded centres of star clusters, but VFTS 682 lies on its own.
"We were very surprised to find such a massive star on its own, and not in a rich star cluster," notes Joachim Bestenlehner, the lead author of the new study and a student at Armagh Observatory in Northern Ireland. "Its origin is mysterious."
This star was spotted earlier in a survey of the most brilliant stars in and around the Tarantula Nebula in the Large Magellanic Cloud. It lies in a stellar nursery: a huge region of gas, dust and young stars that is the most active star-forming region in the Local Group of galaxies . At first glance VFTS 682 was thought to be hot, young and bright, but unremarkable. But the new study using the VLT has found that much of the star's energy is being absorbed and scattered by dust clouds before it gets to Earth -- it is actually more luminous than previously thought and among the brightest stars known.
Red and infrared light emitted by the star can get through the dust, but the shorter-wavelength blue and green light is scattered more and lost. As a result the star appears reddish, although if the view were unobstructed it would shine a brilliant blue-white.
As well as being very bright, VFTS 682 is also very hot, with a surface temperature of about 50 000 degrees Celsius . Stars with these unusual properties may end their short lives not just as a supernova, as is normal for high-mass stars, but just possibly as an even more dramatic long-duration gamma-ray burst , the brightest explosions in the Universe.
Although VFTS 682 seems to now be alone it is not very far away from the very rich star cluster RMC 136 (often called just R 136), which contains several similar "superstars" .
"The new results show that VFTS 682 is a near identical twin of one of the brightest superstars at the heart of the R 136 star cluster," adds Paco Najarro, another member of the team from CAB (INTA-CSIC, Spain).
Is it possible that VFTS 682 formed there and was ejected? Such "runaway stars" are known, but all are much smaller than VFTS 682 and it would be interesting to see how such a heavy star could be thrown from the cluster by gravitational interactions.
"It seems to be easier to form the biggest and brightest stars in rich star clusters," adds Jorick Vink, another member of the team. "And although it may be possible, it is harder to understand how these brilliant beacons could form on their own. This makes VFTS 682 a really fascinating object."
 The VFTS 682 analysis was led by Jorick Vink, Gotz Grafener and Joachim Bestenlehner from the Armagh Observatory,
 The name VFTS is short for VLT-FLAMES Tarantula Survey, an ESO Large Programme led by Christopher Evans of the UK Astronomy Technology Centre, Edinburgh, UK.
 The Local Group is a small group of galaxies that includes the Milky Way and Andromeda galaxies, as well as the Magellanic Clouds and many smaller galaxies.
 For comparison the surface temperature of the Sun is about 5500 degrees Celsius.
 Gamma-ray bursts are among the most energetic events in the Universe and the high energy radiation that they produce can be detected by orbiting space craft. Gamma-ray bursts lasting longer than two seconds are referred to as long bursts and those with a shorter duration are known as short bursts. Long bursts are associated with the supernova explosions of massive young stars in star-forming galaxies. Short bursts are not well understood, but are thought to originate from the merger of two compact objects such as neutron stars.
 If VFTS 682 is at the same distance from Earth as R 136 then it lies about 90 light-years from the centre of the cluster. If the distances are significantly different then the separation could be much greater.
This research was presented in a paper, "The VLT-FLAMES Tarantula Survey III: A very massive star in apparent isolation from the massive cluster R136," to appear in Astronomy & Astrophysics.
The team is composed of Joachim M. Bestenlehner (Armagh Observatory, UK), Jorick S.Vink (Armagh), G. Grafener (Armagh), F. Najarro (Centre of Astrobiology, Madrid, Spain), C. J. Evans (UK Astronomy Technology Centre, Edinburgh, UK), N. Bastian (Excellence Cluster Universe, Garching, Germany; University of Exeter, UK), A. Z. Bonanos (National Observatory of Athens, Greece), E. Bressert (Exeter; ESO; Harvard Smithsonian Center for Astrophysics, Cambridge, USA), P. A. Crowther (University of Sheffield, UK), E. Doran (Sheffield), K. Friedrich (Argelander Institute, University of Bonn, Germany), V.Henault-Brunet (University of Edinburgh, UK), A. Herrero (University of La Laguna, Tenerife, Spain; ESO), A. de Koter (University of Amsterdam; Utrecht University, Netherlands), N. Langer (Argelander Institute), D. J. Lennon (ESA; Space Telescope Science Institute, Baltimore, USA), J. Maiz Apellaniz (Institute of Astrophysics of Andalucia, Granada, Spain), H. Sana (University of Amsterdam), I. Soszynski (Warsaw University, Poland), and W. D. Taylor (University of Edinburgh).
Publicado por Nathaniel en 10:40 No hay comentarios:
Using Microbes to Generate Electricity?
Using bacteria to generate energy is a significant step closer following a breakthrough discovery by scientists at the University of East Anglia (UEA).
Published May 23 in the Proceedings of the National Academy of Sciences (PNAS), the research demonstrates for the first time the exact molecular structure of the proteins which enable bacterial cells to transfer electrical charge.
The discovery means scientists can now start developing ways to 'tether' bacteria directly to electrodes -- creating efficient microbial fuel cells or 'bio-batteries'. The advance could also hasten the development of microbe-based agents that can clean up oil or uranium pollution, and fuel cells powered by human or animal waste.
"This is an exciting advance in our understanding of how some bacterial species move electrons from the inside to the outside of a cell," said Dr Tom Clarke of UEA's School of Biological Sciences.
"Identifying the precise molecular structure of the key proteins involved in this process is a crucial step towards tapping into microbes as a viable future source of electricity."
Funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the US Department of Energy, the project is led by Dr Clarke, Prof David Richardson and Prof Julea Butt of UEA, in collaboration with colleagues at the Pacific Northwest National Laboratory in the US.
In earlier research published by PNAS in 2009, the team demonstrated the mechanism by which bacteria survive in oxygen-free environments by constructing electrical wires that extend through the cell wall and make contact with a mineral -- a process called iron respiration or 'breathing rocks'.
In this latest research, the scientists used a technique called x-ray crystallography to reveal the molecular structure of the proteins attached to the surface of a Shewanella oneidensis cell through which electrons are transferred.
Publicado por Nathaniel en 10:39 No hay comentarios:
Cosmic Explosion Is New Candidate for Most Distant Object in the Universe
A gamma-ray burst detected by NASA's Swift satellite in April 2009 has been newly unveiled as a candidate for the most distant object in the universe. At an estimated distance of 13.14 billion light years, the burst lies far beyond any known quasar and could be more distant than any previously known galaxy or gamma-ray burst. Multiple lines of evidence in favor of a record-breaking distance for this burst, known as GRB 090429B for the 29 April 2009 date when it was discovered, are presented in a paper by an international team of astronomers led by former Penn State University graduate student Antonino Cucchiara, now at the University of California, Berkeley.
The paper has been accepted for publication in the Astrophysical Journal.
The gigantic burst of gamma rays erupted from an exploding star when the universe was less than 4% of its present age, just 520 million years old, and less than 10% of its present size. "The galaxy hosting the progenitor star of GRB 090429B was truly one of the first galaxies in the universe," said Derek Fox, associate professor of astronomy and astrophysics at Penn State and a co-author of the paper. "Beyond the possible cosmic distance record, GRB 090429B illustrates how gamma-ray bursts can be used to reveal the locations of massive stars in the early universe and to track the processes of early galaxy and star formation that eventually led to the galaxy-rich cosmos we see around us today."
Gamma-ray bursts, the brightest explosions known, occur somewhere within the observable universe at a rate of about two per day. Thanks to their extreme brightness, gamma-ray bursts can be detected by Swift and other satellite observatories even when they occur at distances of billions of light years. While the bursts themselves last for minutes at most, their fading "afterglow" light remains observable from premier astronomical facilities for days to weeks. Detailed studies of the afterglow during this time, when feasible, allow astronomers to measure the distance to the burst.
These afterglow measurements were used to determine a cosmic distance record in 2009 for an earlier gamma-ray burst, GRB 090423 at a distance of 13.04 billion light years from Earth, making it temporarily the "most distant object in the universe." This record was surpassed by galaxy discoveries in 2010 and 2011 that pushed the cosmic frontier out to 13.07 billion light years, and potentially even further. "Our extreme estimate of the distance to GRB 090429B makes this a sort of 'revenge of the bursts,'" said Cucchiara. "A gamma-ray burst is once more contending for the title of most distant object in the cosmos -- beyond the previously known most-distant quasars and galaxies."
Less than a week after the record-setting GRB 090423 made headlines around the world, this new burst, GRB 090429B, appeared in the sky with suspiciously similar properties. As with the previous burst, GRB 090429B was a short-lived event, lasting less than 10 seconds, and automated Swift observations showed it to have a relatively faint X-ray afterglow. Cucchiara, then a graduate student at Penn State, woke up in the early morning hours to direct observations at the Gemini North telescope on Mauna Kea, Hawaii, that he hoped would pin down the nature of this burst. Working with coauthors Andrew Levan of the University of Warwick, Nial Tanvir of the University of Leicester, and thesis supervisor Derek Fox of Penn State, Cucchiara found that, while the afterglow was visible in infrared observations, no optical light could be detected. This "drop out" behavior is a distinctive signature of the most-distant objects, and has been used for initial identification of all of the most-distant quasars, galaxies, and gamma-ray bursts.
Cucchiara requested an immediate spectrum of the GRB 090429B afterglow from the Gemini operators, which would have provided a definitive measurement of the distance to the burst. Unfortunately, just as the spectrum was about to be taken, clouds blew in over the summit of Mauna Kea and hid the afterglow from sight. By the next night, the afterglow was too faint to yield a useful spectrum, and over the following nights it faded from view completely. "It was frustrating to lose sight of this burst, but the hints we had were so exciting there was no chance of us letting it go," said Cucchiara, who presented an initial study of the burst as part of his doctoral thesis at Penn State.
Determined not to let GRB 090429B become "the burst that got away," the team spent two years carrying out a careful examination of their data to see if the burst is truly a candidate record-breaker, or might be a partially-obscured burst in a galaxy at a less dramatic distance. Importantly, this work has meant gathering new data -- deep observations with Gemini and the Hubble Space Telescope that would have revealed a galaxy at the burst position in any of the less-dramatic scenarios. This evidence, including the missing galaxy, indicates that the burst is extremely likely -- a 99.3-percent chance -- to be the most distant cosmic explosion, beyond the record set by GRB 090423. "Like the best politicians or talent-show contestants, the more we examined this burst, the better it looked," says Levan, the paper's second author.
Whether GRB 090429B is now the most distant object in the universe depends on several factors which are not precisely known. First, it must lie beyond the 13.07-billion-light-year distance to a galaxy reported in 2010 by a team of astronomers led by Matthew Lehnert at the Observatoire de Paris. This is very likely to be the case, at 98.9% probability, but is not certain. It also has to lie beyond the distance of a galaxy reported in 2011 by a team of astronomers led by Rychard Bouwens of U.C. Santa Cruz. This could be either easy or hard: The Bouwens team estimates that there is a 20% chance their galaxy is not a record breaker at all, but simply a faint galaxy at a relatively modest distance; on the other hand, if the Bouwens galaxy is a record-breaker, it is very distant indeed, from 13.11 to 13.28 billion light years away, and there is only a 4.8% chance that GRB 090429B is more distant than that. Overall, and treating these uncertainties as perfectly understood, there is a 23% chance that GRB 090429B is now the most distant known object in the Universe, the astronomers said.
With better luck, or more advanced facilities, it should be possible in the future to use the bright afterglows of bursts like GRB 090423 and GRB 090429B to explore the conditions of star and galaxy formation at these early cosmic epochs in detail. "Discovering extremely distant bursts is pretty fun," says Fox, "but we suspect there is a whole lot more information in the bursts, waiting for us, that we have yet to access."
Publicado por Nathaniel en 10:37 No hay comentarios:
Unique Canine Tooth from 'Peking Man' Found in Swedish Museum Collection
Fossils from so-called Peking man are extremely rare, as most of the finds disappeared during World War II. A unique discovery has been made at the Museum of Evolution at Uppsala University -- a canine tooth from Peking Man, untouched since it was dug up in the 1920s in China.
"This is an absolutely incredible find. We and our Chinese colleagues are overwhelmed. With today's technology, a canine tooth that has not been handled can tell us so much more than in the past, such as what they ate," says Per Ahlberg, professor of evolutionary developmental biology at Uppsala University.
Swedish paleontologists were the first scientists to go to China in the early 20th century, and they carried out a series of expeditions in collaboration with Chinese colleagues. They found large numbers of fossils of dinosaurs and other vertebrates. The material was sent to Sweden and the well-known paleontologist Carl Wiman, who identified and described the fossils. But when the direction of research changed after Wiman's death, 40 cartons were left unopened and forgotten -- until know. In recent weeks, they have been opened by Per Ahlberg, his colleague Martin Kundrát, and Museum Director Jan Ove Ebbestad, who had drawn attention to the cartons in the storeroom at the Museum of Evolution.
Recently, they have gone through the material together with leading Chinese paleontologists from the Beijing Institute of Vertebrate Paleontology and Paleoanthropology, who were excited when their Swedish colleagues contacted them. The Museum of Evolution has the best collection of Chinese fossils of dinosaurs and other vertebrates outside of China, and the contents of the 40 cartons further enhance the value of the collection.
The fossil material comes from several different areas in China. In Zhoukoudian, southwest of Beijing, a canine tooth was found from Homo erectus -- that is, Peking man. Then rich finds were made of skulls and other skeletal parts, but all of this disappeared in a mysterious way during World War II. All that remains in China today are five teeth and a few pieces of skull bone that were found in the 1950s and 1960s. So the three teeth from Peking man at the Museum of Evolution have been regarded as being among the most valuable parts of the collection. And now they have uncovered a fourth tooth -- and it is untouched.
According to Professor Liu Wu from the Chinese Academy of Sciences, it is a fractured, but otherwise well-preserved canine tooth.
"This is an extremely important find. It is the only canine tooth in existence. It can yield important information about how Homo erectus lived in China," he says.
The tooth is to be examined with modern technology. By studying how the tooth was worn down and looking at possible microscopic mineral granules from plant remains, it may be possible to puzzle out what Peking man ate. Combining this with the other material in the cartons, these scientists hope to be able to reconstruct some of the plant and animal life that existed in Peking man's environment.
Publicado por Nathaniel en 10:36 No hay comentarios:
miércoles, 11 de mayo de 2011
Night Sky News: See the Tightest Planet Gathering Yet This Century
Image courtesy StarDate Magazine
Talk about an early morning eye-opener! Every day this month, about 20 to 45 minutes before sunrise, sky-watchers will get a rare opportunity to watch four worlds—Mercury, Venus, Mars, and Jupiter—in the closest planetary grouping yet seen this century.
This, planetary conjunction—astro-lingo for when planets cluster together in the heavens—has provided some impressive sights already. But the early-bird sky show is really culminating this week as they form their tightest grouping yet!
Jupiter, the gas giant and second brightest of the bunch, will glide past Venus on May 10 and 11, making the larger world easy to spot despite it being less than a quarter as bright as the goddess of love. Most impressive is that the two planets will be separated by only 0.5 degrees, which means you could easily cover the starlike pair with just your thumb on an outstretched arm.
Then, on May 12 all four worlds will be clustered within 6 degrees of each other in the dawn sky. That’s equal to the width of 12 full moon disks side by side—quite a pretty sight.
Faint little Mercury is the third brightest planet in the parade, just to the lower right of the Venus-Jupiter pair. But what makes it a challenging target is that Mercury is five to ten times fainter than Jupiter and much closer to the horizon. The innermost planet will remain a few degrees to the lower right of the brighter Venus throughout this period.
However, ruddy colored Mars is the trickiest to spot because it’s just one-hundredth as bright as Venus. The red planet starts very low in the sky, but eventually catches up with the Venus-Mercury pairing this week.
Your best bet to pick out Mercury and Mars through the bright twilight is by using binoculars when you scan just below Venus.
While this planetary alignment can be glimpsed from around the world, best views will be centered around the tropics, where the planets will shine brighter and higher in the predawn sky.
For observers in mid-latitude regions such as southern Canada, most of the continental U.S., and Europe, the planets will hug the eastern horizon very closely, making it more of a challenge to see the entire set.
No matter where you are, the most important advice is to get a clear, unobstructed view of the low eastern horizon 30 to 45 minutes before your local sunrise.
This dazzling planetary meeting will begin to slowly disband in the second half of May, but as a grand finale to the sky show, our own crescent moon will add to the mood from May 29 to 31, making for a picturesque pose with Jupiter and then Venus.
Sky-watchers haven’t seen a cosmic morning lineup like this since 1996! And if you miss this one, you will have a long wait, because the next big planetary conjunction—which will involve all five of the naked-eye planets, plus the moon—won’t occur until September 8, 2040.While all the hoopla surrounds the four bright planets, there are two other members of the club getting in on the action.
Both Uranus and Neptune sit to the far upper right of the quadruple pack of planets in the southeastern sky. They are both significantly fainter, and so you will need binoculars to glimpse them.
Neither will look all that impressive, appearing as greenish-blue tinted, fuzzy stars. A small telescope, however, will begin to reveal their tiny disks.
Out of the eight official planetary members of our solar system, we are lucky enough to see six huddled together in one small section of the sky.
We live on one of the remaining member worlds, so that leaves one missing: Where is Saturn? The ringed gas giant sits by its lonesome in the evening sky, shining brightly high above the southern horizon.
Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.
Publicado por Nathaniel en 16:22 No hay comentarios:
NASA's Dawn Spacecraft Captures First Image of Nearing Asteroid
NASA's Dawn spacecraft has obtained its first image of the giant asteroid Vesta, which will help fine-tune navigation during its approach. Dawn is expected to achieve orbit around Vesta on July 16, when the asteroid is about 188 million kilometers (117 million miles) from Earth.
The image from Dawn's framing cameras was taken on May 3 when the spacecraft began its approach and was approximately 1.21 million kilometers (752,000 miles) from Vesta. The asteroid appears as a small, bright pearl against a background of stars. Vesta is also known as a protoplanet, because it is a large body that almost formed into a planet.
"After plying the seas of space for more than a billion miles, the Dawn team finally spotted its target," said Carol Raymond, Dawn's deputy principal investigator at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "This first image hints of detailed portraits to come from Dawn's upcoming visit."
Vesta is 530 kilometers (330 miles) in diameter and the second most massive object in the asteroid belt. Ground- and space-based telescopes obtained images of the bright orb for about two centuries, but with little surface detail.
Mission managers expect Vesta's gravity to capture Dawn in orbit on July 16. To enter orbit, Dawn must match the asteroid's path around the sun, which requires very precise knowledge of the body's location and speed. By analyzing where Vesta appears relative to stars in framing camera images, navigators will pin down its location and enable engineers to refine the spacecraft's trajectory.
Dawn will start collecting science data in early August at an altitude of approximately 1,700 miles (2,700 kilometers) above the asteroid's surface. As the spacecraft gets closer, it will snap multi-angle images, allowing scientists to produce topographic maps. Dawn will later orbit at approximately 200 kilometers (120 miles) to perform other measurements and obtain closer shots of parts of the surface. Dawn will remain in orbit around Vesta for one year. After another long cruise phase, Dawn will arrive in 2015 at its second destination, Ceres, an even more massive body in the asteroid belt.
Gathering information about these two icons of the asteroid belt will help scientists unlock the secrets of our solar system's early history. The mission will compare and contrast the two giant bodies shaped by different forces. Dawn's science instruments will measure surface composition, topography and texture. Dawn will also measure the tug of gravity from Vesta and Ceres to learn more about their internal structures. The spacecraft's full odyssey will take it on a 5-billion-kilometer (3-billion-mile) journey, which began with its launch in September 2007.
Dawn's mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala.
The University of California in Los Angeles is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The framing cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research in Katlenburg-Lindau in Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research in Berlin and in coordination with the Institute of Computer and Communication Network Engineering in Braunschweig. The framing camera project is funded by NASA, the Max Planck Society and DLR.
For more information about Dawn, visit: http://www.nasa.gov/dawn
Publicado por Nathaniel en 16:20 No hay comentarios:
Fundamental Question on How Life Started Solved: Supercomputer Calculates Carbon Nucleus
The researchers published their results in the coming issue of the scientific journal Physical Review Letters.
"Attempts to calculate the Hoyle state have been unsuccessful since 1954," said Professor Dr. Ulf-G. Meißner (Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn). "But now, we have done it!" The Hoyle state is an energy-rich form of the carbon nucleus. It is the mountain pass over which all roads from one valley to the next lead: From the three nuclei of helium gas to the much larger carbon nucleus. This fusion reaction takes place in the hot interior of heavy stars. If the Hoyle state did not exist, only very little carbon or other higher elements such as oxygen, nitrogen and iron could have formed. Without this type of carbon nucleus, life probably also would not have been possible.
The search for the "slave transmitter"
The Hoyle state had been verified by experiments as early as 1954, but calculating it always failed. For this form of carbon consists of only three, very loosely linked helium nuclei -- more of a cloudy diffuse carbon nucleus. And it does not occur individually, only together with other forms of carbon. "This is as if you wanted to analyze a radio signal whose main transmitter and several slave transmitters are interfering with each other," explained Prof. Dr. Evgeny Epelbaum (Institute of Theoretical Physics II at Ruhr-Universität Bochum). The main transmitter is the stable carbon nucleus from which humans -- among others -- are made. "But we are interested in one of the unstable, energy-rich carbon nuclei; so we have to separate the weaker radio transmitter somehow from the dominant signal by means of a noise filter."
What made this possible was a new, improved calculating approach the researchers used that allowed calculating the forces between several nuclear particles more precisely than ever. And in JUGENE, the supercomputer at Forschungszentrum Jülich, a suitable tool was found. It took JUGENE almost a week of calculating. The results matched the experimental data so well that the researchers can be certain that they have indeed calculated the Hoyle state.
More about how the Universe came into existence
"Now we can analyze this exciting and essential form of the carbon nucleus in every detail," explained Prof. Meißner. "We will determine how big it is, and what its structure is. And it also means that we can now take a very close look at the entire chain of how elements are formed."
In future, this may even allow answering philosophical questions using science. For decades, the Hoyle state was a prime example for the theory that natural constants must have precisely their experimentally determined values, and not any different ones, since otherwise we would not be here to observe the Universe (the anthropic principle). "For the Hoyle state this means that it must have exactly the amount of energy it has, or else, we would not exist," said Prof. Meißner. "Now we can calculate whether -- in a changed world with other parameters -- the Hoyle state would indeed have a different energy when comparing the mass of three helium nuclei." If this is so, this would confirm the anthropic principle
Publicado por Nathaniel en 16:19 No hay comentarios:
Wine Yeasts Reveal Prehistoric Microbial World
When having a glass of wine or beer, have you ever wondered why and how yeast "learned" to produce these superb food products? Yeasts are unicellular fungi and so far over 1,500 different species have been described. Among them are important industrial organisms, pathogens and model organisms which help us to understand how eukaryotic cells work.
However, one of the most well-known characteristics of yeast is the ability of Saccharomyces cerevisiae, baker's yeast, to ferment sugar to 2-carbon components, in particular ethanol, without completely oxidising it to carbon dioxide, even in the presence of oxygen, as many other microbes do. This fermentative ability is essential for the production of wine, beer and many other alcoholic beverages.
Why do Saccharomyces yeasts actually do this and what were the driving forces behind the evolution of this phenomenon?
For several years, the yeast molecular genetics group at Lund University in Sweden and their counterparts in Milan have been trying to reconstruct the evolutionary history of ethanol production. In their recent article published in Nature Communications they compared two wine yeasts, S. cerevisiae and Dekkera bruxellensis, which in nature often occupy a similar niche, using a variety of approaches including comparative genomics which enabled them to add the time dimension to their molecular reconstructions.
The two yeasts studied are not very closely related and the two lineages separated more than 200 million years ago. However, approximately 100-150 million years ago, both yeasts experienced very similar environmental conditions, with the sudden appearance of modern fruits containing high amounts of available sugars, and environmental pressures, such as fierce competition from other microbes. Both lineages, independently and in parallel, developed the ability to make and accumulate ethanol in the presence of oxygen, and resistance to high ethanol concentration, and have been using this ability as a weapon to outcompete other microbes which are very sensitive to ethanol. Surprisingly, both yeasts used the same molecular tool, global promoter rewiring, to change the regulation pattern of the expression of hundreds of genes involved in sugar degradation.
"Our results now help to reconstruct the original environment and evolutionary trends that operated within the microbial community in the remote past," says Jure Piškur, who is a professor of molecular genetics at Lund University and at the University of Nova Gorica, Slovenia.
"In addition, we can now use the knowledge we have obtained to develop new yeast strains, which could be beneficial for wine and beer fermentation and in biofuel production."
Publicado por Nathaniel en 16:17 No hay comentarios:
The Oceans’ Oddest Creatures and Why They Matter
Marine creatures are among the strangest, most beautiful and least known animals on Earth. Their intriguing mating strategies, defensive weapons, shape-shifting and camouflage abilities make for great stories and amazing photographs.
Read more from Ellen Prager about the intriguing animals of the oceans in an exclusive excerpt from the new book Sex Drugs and Sea Slime.
Some of the best of those tales and images appear in the new book Sex, Drugs and Sea Slime, by marine biologist Ellen Prager.
"I’ve always been intrigued by these wonderful stories about marine life that most people never get to hear, You know they’re the stories that over beers your colleagues tell you," Prager said. "But it’s not the stuff that typically gets out to the public."
Publicado por Nathaniel en 16:15 No hay comentarios:
WikiLeaks Threatens Its Own Leakers With $20 Million Penalty
WikiLeaks founder Julian Assange now makes his associates sign a draconian nondisclosure agreement that, among other things, asserts that the organization’s huge trove of leaked material is “solely the property of WikiLeaks,” according to a report Wednesday.
“You accept and agree that the information disclosed, or to be disclosed to you pursuant to this agreement is, by its nature, valuable proprietary commercial information,” the agreement reads, “the misuse or unauthorized disclosure of which would be likely to cause us considerable damage.”
The confidentiality agreement (.pdf), revealed by the New Statesman, imposes a penalty of 12 million British pounds– nearly $20 million — on anyone responsible for a significant leak of the organization’s unpublished material. The figure is based on a “typical open-market valuation” of WikiLeaks’ collection, the agreement claims.
Interestingly, the agreement warns that any breach is likely to cause WikiLeaks to lose the “opportunity to sell the information to other news broadcasters and publishers.”
WikiLeaks is not known to have sold any of its leaked material, though Assange has discussed the possibility in the past. The organization announced in 2008 that it was auctioning off early access to thousands of e-mails belonging to a top aide to Venezuelan president Hugo Chavez, but the auction ultimately fell apart.
Also protected by the agreement is “the fact and content of this agreement and all newsworthy information relating to the workings of WikiLeaks.”
The New Statesman’s copy is unsigned, so whoever leaked it might be safe from legal action by WikiLeaks.
Publicado por Nathaniel en 16:14 No hay comentarios:
domingo, 8 de mayo de 2011
Mysterious New Human Coexisted with Neanderthals: Photos
Neanderthals shared Europe with a mysterious member of our genus that may represent an entirely new species of human, suggests a paper accepted for publication in the Journal of Human Evolution.
The study describes the recently unearthed remains of a hominid from what is now Serbia. The remains -- a fossilized jaw and teeth -- date to at least 113,000 years ago.The specimen is primitive and does not show any Neanderthal-derived traits," lead author Mirjana Roksandic told Discovery News. "It could be a simple case of one non-representative member of a larger population that is morphologically primitive, or a representative member of a more primitive population that remained in the Balkans while Neanderthals developed in the rest of Europe."
Roksandic, an associate professor of anthropology at the University of Winnipeg, and her team have not, however, ruled out that the individual belonged to a new Homo species.
Europe appears to have been home to several such species over the past 1.7 million years, including Homo georgicus, Homo antecessor, Homo heidelbergensis and Homo neanderthalensis.For the study, the researchers performed a CT scan and other analysis of the jaw and teeth that were discovered at Mala Balanica Cave in Serbia.
Co-author Dusan Mihailovic told Discovery News that "a rich tool assemblage" was found in an upper part of the geological sequence at the site. Additional excavation work may uncover older tools, he said.The cave complex is located in a Central Balkans region that has been called a "hotspot of biodiversity."
"Hotspot of biodiversity as a characteristic of the Balkans was put forward by biogeographers to indicate that most of the plant and animal species that repopulated the continent after glaciations came from the Balkans," Roksandic explained. "In the north of the continent all species of the eastern, and a fair number of the western, part are from the Balkans source."
It remains unclear whether or not a new human species originated in the Balkans. This region was never very isolated, as its southern portion remained open throughout the Pleistocene. The new Homo discovery is therefore all the more puzzling.The fate of Neanderthals and the Serbian individual's group remains unclear, but prior research has determined that modern humans did interbreed, at least to some extent, with Neanderthals. Other anthropologists have suggested that modern humans also may have interbred with additional Homo species from Europe.
"It would probably be best to describe Neanderthals and other Pleistocene humans as morphospecies," Roksandic said. "This acknowledges differences but does not discuss their phylogenetic relationship. They are morphologically different, (so) would it prevent them from recognizing each other as potential mates? Hard to say."
She added that according to some researchers it takes more than 2 million years to achieve complete genetic incompatibility between species. The various prehistoric human groups may therefore have enjoyed connections despite their anatomical and behavioral differences.
Publicado por Nathaniel en 13:22 No hay comentarios:
Publicado por Nathaniel en 13:20 No hay comentarios:
Scientists "See" Ocean Floor via Sonar
Publicado por Nathaniel en 13:19 No hay comentarios:
Einstein Theories Confirmed by NASA Gravity Probe
Two key predictions of Albert Einstein's general theory of relativity have been confirmed by NASA's Gravity Probe B mission, scientists announced this week.
"We've completed this landmark experiment testing Einstein's universe, and Einstein survives," principal investigator Francis Everitt, of Stanford University in California, said during a press briefing.
Launched in 2004, the Gravity Probe B mission used four ultraprecise gyroscopes—devices used to measure orientation—housed in a satellite to measure two aspects of Einstein's theory about gravity.
The first is the geodetic effect, which is the warping of space and time—or spacetime—around a gravitational body, such as a planet.
One common way to visualize the geodetic effect is to think of Earth as a bowling ball and spacetime as a trampoline. Earth's gravity warps spacetime the same way a bowling ball weighs down the middle of a trampoline.
The second effect of gravity tested by Gravity Probe B is frame dragging, which is the amount that a spinning object pulls the fabric of spacetime along with it.
Doing What Einstein Thought Impossible
To conduct these tests, Gravity Probe B used a device called a star tracker to keep one end pointed at a single star, IM Pegasi, while in a polar orbit 400 miles (644 kilometers) above Earth.
If we lived in a universe that behaved as envisioned by Isaac Newton—in which the geodetic effect and frame dragging don't occur—then the gyroscopes would stay aligned with the star forever.
In Einstein's universe, however, the direction of the spin axis of Gravity Probe B's gyroscopes should gradually change due to the mass and rotation of Earth.
"Imagine the Earth is immersed in honey, and you can imagine the honey would be dragged around and [an object in the honey] would also be dragged around," Everitt said. "That's what happens in the gyroscope."
Sifting through the data, the team found evidence of an angular change in the gyroscopes' orientation of about 6,600 milliarcseconds over the course of a year.
A milliarcsecond, Everitt explained, "is the width of a human hair seen at the distance of 10 miles [16 kilometers]. It really is a rather small angle, and this is the accuracy which Gravity Probe B had to achieve."
The change is so small, in fact, that Einstein didn't think measuring it was even possible.
In his 1953 book The Meaning of Relativity, Einstein wrote that frame-dragging effects "are actually present according to our theory, although their magnitude is so small that confirmation of them by laboratory experiments is not to be thought of."
But now, "thanks to NASA," Everitt said, "we've done more than think about them. We've actually measured them."
Gravity Findings to Unravel Distant Mysteries?
Although the results are only now being released, the Gravity Probe B satellite has completed its work, and it was decommissioned in December 2010.
Funded since 1963, Gravity Probe B is one of the longest running projects in NASA history. Scientists had the idea for the experiment before the required technology—such as the star tracker and gyroscopes—even existed.
The probe's predecessor, Gravity Probe A, was launched in 1976 and also confirmed a key aspect of Einstein's general theory of relativity, namely that a clock on Earth will run slower than one aboard an orbiting spacecraft.
While it's been widely accepted that the geodetic effect and frame dragging occur, it was important to confirm them with experiments, physicist Clifford Will, of Washington University in St. Louis, said at the press conference.
"While the result in this case does support Einstein, it didn't have to," he said.
In addition, the findings, detailed online in the journal Physical Review Letters, may help scientists understand some of the most cataclysmic events in the universe.
"Measuring the frame-dragging effect caused by the Earth's rotation has implications beyond our planet," said Will, who was not involved in the Gravity Probe B project.
For example, he said, frame dragging likely plays a role in triggering energetic bursts from quasars, very distant galaxies that have actively feeding—and rapidly rotating—supermassive black holes at their hearts.
Publicado por Nathaniel en 13:16 No hay comentarios:
Domestic Surveillance Court Approved All 1,506 Warrant Applications in 2010
The secretive Foreign Intelligence Surveillance Court approved all 1,506 government requests to electronically monitor suspected “agents” of a foreign power or terrorists on U.S. soil last year, according to a Justice Department report released under the Freedom of Information Act.
The two-page report, which shows about a 13 percent increase in the number of applications for electronic surveillance between 2009 and 2010, was obtained by the Federation of American Scientists and published Friday.
“The FISC did not deny any applications in whole, or in part,” according to the April 19 report to Sen. Majority Leader Harry Reid (D-Nevada).
The 11-member court denied two of 1,329 applications for domestic-intelligence surveillance in 2009. The FBI is the primary agency making those requests.
Whether the FISA court, whose business is conducted behind closed doors, is rubber-stamping the requests is a matter of debate.
“That’s been a traditional concern that the court might have become a rubber stamp and that it’s approval is only a formality,” Steven Aftergood, the director of the Project on Government Secrecy for the Federation of American Scientists, said by telephone. “The government’s argument, and it’s also an argument that has been made occasionally by the judges, is in fact the Justice Department has grasped the court’s expectations so well that the only applications they submit to the court are ones that are likely to meet its approval.”
The court, set up in 1978, issues warrants for domestic surveillance that are unlike the warrants issued in criminal investigations. The secret court warrants, under the authority of the Foreign Intelligence Surveillance Act, grant the government broad authority to secretly monitor the electronic communications of persons in the United States, generally for intelligence purposes only.
The targets of a FISA warrant may never learn of the surveillance. Whereas subjects of non-FISA warrants may challenge the warrants and the evidence gathered if it is used in a criminal prosecution.
Aftergood notes that the figures, whether they amount to rubber-stamping or not, do not account for the warrantless monitoring program President George W. Bush adopted in the wake of the 2001 terror attacks. Under the Terror Surveillance Program, exposed in 2005 by The New York Times, the government conceded it was eavesdropping — without warrants — on the electronic communications of Americans if they were communicating with somebody overseas believed linked to terrorism.
The Justice Department report, meanwhile, said the FBI issued 24,287 “national security letter” requests last year on 14,212 people, “a substantial increase from the 2009 level of 14,788 NSL requests concerning 6,114 U.S. persons,” Aftergood wrote in a blog post. In 2008, there were 24,744 requests regarding 7,225 people.
National security letters are written demands from the FBI that compel internet service providers, credit companies, financial institutions and others to hand over confidential records about their customers, such as subscriber information, phone numbers and e-mail addresses, websites visited and more.
They do not require court approval, and the FBI need merely assert that the information is “relevant” to an investigation, and anyone who gets a national security letter is prohibited from even disclosing that they’ve received one.
Here is a link to all 32 Foreign Intelligence Surveillance Court annual reports to Congress made available by the Federation of American Scientists.
Publicado por Nathaniel en 13:14 No hay comentarios:
Mars Express Sees Deep Fractures on Mars
Newly released images from the European Space Agency's Mars Express show Nili Fossae, a system of deep fractures around the giant Isidis impact basin. Some of these incisions into the martian crust are up to 500 m deep and probably formed at the same time as the basin.
on Mars, northeast of the Syrtis Major volcanic province, on the northwestern edge of the giant Isidis impact basin. Graben refers to the lowered terrain between two parallel faults or fractures in the rocks that collapses when tectonic forces pull the area apart. The Nili Fossae system contains numerous graben concentrically oriented around the edges of the basin.
It is thought that flooding of the basin with basaltic lava after the impact that created it resulted in subsidence of the basin floor, adding stress to the planet's crust, which was released by the formation of the fractures.
A strongly eroded impact crater is visible to the bottom right of the image. It measures about 12 km across and exhibits an ejecta blanket, usually formed by material thrown out during the impact. Two landslides have taken place to the west of the crater. Whether they were a direct result of the impact or occurred later is unknown.
A smaller crater, measuring only 3.5 km across, can be seen to the left of centre in the image and this one does not exhibit any ejecta blanket material. It has either been eroded or may have been buried.
The surface material to the top left of the image is much darker than the rest of the area. It is most likely formed of basaltic rock or volcanic ash originating from the Syrtis Major region. Such lava blankets form when large amounts of low-viscosity basaltic magma flow across long distances before cooling and solidifying. On Earth, the same phenomenon can be seen in the Deccan Traps in India.
Nili Fossae interests planetary scientists because observations taken with telescopes on Earth and published in 2009 have shown that there is a significant enhancement in Mars' atmospheric methane over this area, suggesting that methane may be being produced there. Its origin remains mysterious, however, and could be geological or perhaps even biological.
As a result, understanding the origin of methane on Mars is high on the priority list and in 2016, ESA and NASA plan to launch the ExoMars Trace Gas Orbiter to investigate further. Nili Fossae will be observed with great interest.
Publicado por Nathaniel en 13:12 No hay comentarios:
Single-Cell Marine Organisms Offer Clues to How Cells Interact With the Environment
ScienceDaily (May 8, 2011) — From a bucket of seawater, scientists have unlocked information that may lead to deeper understanding of organisms as different as coral reefs and human disease. By analyzing genomes of a tiny, single-celled marine animal, they have demonstrated a possible way to address diverse questions such as how diseased cells differ from neighboring healthy cells and what it is about some Antarctic algae that allows them to live in warming waters while other algae die out.
Debashish Bhattacharya, professor of ecology, evolution and natural resources in Rutgers' School of Environmental and Biological Sciences, and Ramunas Stepanauskas and Hwan Su Yoon of the Bigelow Laboratory of Ocean Sciences, have published their results in the journal Science. They used sophisticated new technologies to sequence the genomes of individual picobilophytes, tiny microbes first discovered in 2007. At less than 10 micrometers across, they are some of the tiniest marine animals known to science.
"If we can peer inside the genome of a single cell and reconstruct its history, we can do that for many cells and figure out their interactions with other cells in the environment," Bhattacharya said. For example, why do different cancer cells from the same tumor grow at different rates? Their genomes might contain the answer, and the answer might lead to more effective treatment strategies.
"Our results demonstrate how single cell genomics opens a window into the natural drama that constantly takes place in each drop of seawater -- a drama featuring predation, viral infections, and the divergent fate of close relatives," Stepanauskas said. "The outcomes of this drama have profound effects on the lives of larger marine organisms, such as commercially valuable fish."
Bhattacharya and Oscar Schofield, professor of marine science, are now working to apply these techniques to Antarctic algae. Some species traditionally found along the Western Antarctic Peninsula are dying off as the water warms, and others, not seen before there, are moving in. If Bhattacharya and Schofield can sequence the genomes of those algae cell by cell, as he and Stepanauskas have done with picobilophytes, they might learn much more about how climate change has affected the ecosystem in that region.
Bigelow Laboratory's Single Cell Genomics Center, established by Stepanauskas and his colleagues, has analyzed more than150,000 individual microbial cells, shedding new light on the invisible majority of our planets biological diversity.
When picobilophytes were discovered in 2007, scientists believed they were photosynthetic -- that is, that, like green plants, they converted carbon dioxide into food, using energy from sunlight. But these tiny cells have been impossible to culture in the laboratory and this may have been because they were starving, deprived of their natural food sources.
For this project, the scientists hauled 50 milliliters (a handful) of seawater out of Boothbay Harbor in Maine, the home of the Bigelow Laboratory. They used a technique called fluorescence activated cell sorting to separate photosynthetic from non-photosynthetic (heterotrophic) cells. They were surprised to find that picobilophytes lacked chlorophyll. They sequenced the genomes of three picobilophytes and were excited to find, in one of them, a new virus, whose circular genome they were able to reconstruct. They were also able to identify and sequence the DNA of creatures the picobilophytes had presumably eaten.
For a marine biologist like Bhattacharya, however, the immediate prospects in his own field hold the most promise. "There is a lot of uncharted biodiversity on our planet that we can't get a hold of because we can't cultivate the cells," he said. "Now, if you can reconstruct the nuclear genomes of individual cells in a sample of seawater, you can begin to infer not only the numbers and kinds of organisms that inhabit a particular ecosystem but also the functions of all the genes in their individual genomes."
Publicado por Nathaniel en 13:09 No hay comentarios:
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