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  • richardmitnick 6:18 pm on October 28, 2014 Permalink | Reply
    Tags: Physics, , ,   

    From Brown: “Can the wave function of an electron be divided and trapped?” 

    Brown University
    Brown University

    October 28, 2014
    Kevin Stacey 401-863-3766

    Electrons are elementary particles — indivisible, unbreakable. But new research suggests the electron’s quantum state — the electron wave function — can be separated into many parts. That has some strange implications for the theory of quantum mechanics.

    New research by physicists from Brown University puts the profound strangeness of quantum mechanics in a nutshell — or, more accurately, in a helium bubble.

    Experiments led by Humphrey Maris, professor of physics at Brown, suggest that the quantum state of an electron — the electron’s wave function — can be shattered into pieces and those pieces can be trapped in tiny bubbles of liquid helium. To be clear, the researchers are not saying that the electron can be broken apart. Electrons are elementary particles, indivisible and unbreakable. But what the researchers are saying is in some ways more bizarre.

    The electron wave function A canister of liquid helium inside the blue cylinder allowed researchers to experiment with tiny electron bubbles only 3.6 nanometers in diameter. The work suggests that the wave function of an electron can be split and parts of it trapped in smaller bubbles. Photo: Mike Cohea/Brown University

    In quantum mechanics, particles do not have a distinct position in space. Instead, they exist as a wave function, a probability distribution that includes all the possible locations where a particle might be found. Maris and his colleagues are suggesting that parts of that distribution can be separated and cordoned off from each other.

    “We are trapping the chance of finding the electron, not pieces of the electron,” Maris said. “It’s a little like a lottery. When lottery tickets are sold, everyone who buys a ticket gets a piece of paper. So all these people are holding a chance and you can consider that the chances are spread all over the place. But there is only one prize — one electron — and where that prize will go is determined later.”

    If Maris’s interpretation of his experimental findings is correct, it raises profound questions about the measurement process in quantum mechanics. In the traditional formulation of quantum mechanics, when a particle is measured — meaning it is found to be in one particular location — the wave function is said to collapse.

    “The experiments we have performed indicate that the mere interaction of an electron with some larger physical system, such as a bath of liquid helium, does not constitute a measurement,” Maris said. “The question then is: What does?”

    And the fact that the wave function can be split into two or more bubbles is strange as well. If a detector finds the electron in one bubble, what happens to the other bubble?

    “It really raises all kinds of interesting questions,” Maris said.

    The new research is published in the Journal of Low Temperature Physics.

    Electron bubbles

    Scientists have wondered for years about the strange behavior of electrons in liquid helium cooled to near absolute zero. When an electron enters the liquid, it repels surrounding helium atoms, forming a bubble in the liquid about 3.6 nanometers across. The size of the bubble is determined by the pressure of the electron pushing against the surface tension of the helium. The strangeness, however, arises in experiments dating back to the 1960s looking at how the bubbles move.

    In the experiments, a pulse of electrons enters the top of a helium-filled tube, and a detector registers the electric charge delivered when electron bubbles reach the bottom of the tube. Because the bubbles have a well-defined size, they should all experience the same amount of drag as they move, and should therefore arrive at the detector at the same time. But that’s not what happens. Experiments have detected unidentified objects that reach the detector before the normal electron bubbles. Over the years, scientists have cataloged 14 distinct objects of different sizes, all of which seem to move faster than an electron bubble would be expected to move.

    “They’ve been a mystery ever since they were first detected,” Maris said. “Nobody has a good explanation.”

    Several possibilities have been proposed. The unknown objects could be impurities in the helium—charged particles knocked free from the walls of the container. Another possibility is that the objects could be helium ions — helium atoms that have picked up one or more extra electrons, which produce a negative charge at the detector.

    But Maris and his colleagues, including Nobel laureate and Brown physicist Leon Cooper, believe a new set of experiments puts those explanations to rest.

    New experiments

    The researchers performed a series of electron bubble mobility experiments with much greater sensitivity than previous efforts. They were able to detect all 14 of the objects from previous work, plus four additional objects that appeared frequently over the course of the experiments. But in addition to those 18 objects that showed up frequently, the study revealed countless additional objects that appeared more rarely.

    In effect, Maris says, it appears there aren’t just 18 objects, but an effectively infinite number of them, with a “continuous distribution of sizes” up to the size of the normal electron bubble.

    “That puts a dagger in the idea that these are impurities or helium ions,” Maris said. “It would be hard to imagine that there would be that many impurities, or that many previously unknown helium ions.”

    The only way the researchers can think of to explain the results is through “fission” of the wave function. In certain situations, the researchers surmise, electron wave functions break apart upon entering the liquid, and pieces of the wave function are caught in separate bubbles. Because the bubbles contain less than the full wave function, they’re smaller than normal electron bubbles and therefore move faster.

    In their new paper, Maris and his team lay out a mechanism by which fission could happen that is supported by quantum theory and is in good agreement with the experimental results. The mechanism involves a concept in quantum mechanics known as reflection above the barrier.

    In the case of electrons and helium, it works like this: When an electron hits the surface of the liquid helium, there’s some chance that it will cross into the liquid, and some chance that it will bounce off and carom away. In quantum mechanics, those possibilities are expressed as part of the wave function crossing the barrier, and part of it being reflected. Perhaps the small electron bubbles are formed by the portion of the wave function that goes through the surface. The size of the bubble depends on how much wave function goes through, which would explain the continuous distribution of small electron bubble sizes detected in the experiments.

    The idea that part of the wave function is reflected at a barrier is standard quantum mechanics, Cooper said. “I don’t think anyone would argue with that,” he said. “The non-standard part is that the piece of the wave function that goes through can have a physical effect by influencing the size of the bubble. That is what is radically new here.”

    Further, the researchers propose what happens after the wave function enters the liquid. It’s a bit like putting a droplet of oil in a puddle of water. “Sometime your drop of oil forms one bubble,” Maris said, “Sometimes it forms two, sometimes 100.”

    There are elements within quantum theory that suggest a tendency for the wave function to break up into specific sizes. By Maris’s calculations, the specific sizes one might expect to see correspond roughly to the 18 frequently occurring electron bubble sizes.

    “We think this offers the best explanation for what we see in the experiments,” Maris said. We’ve got this body of data that goes back 40 years. The experiments are not wrong; they’ve been done by multiple people. We have a tradition called Occam’s razor, where we try to come up with the simplest explanation. This, so far as we can tell, is it.”

    But it does raise some interesting questions that sit on the border of science and philosophy. For example, it’s necessary to assume that the helium does not make a measurement of the actual position of the electron. If it did, any bubble found not to contain the electron would, in theory, simply disappear. And that, Maris says, points to one of the deepest mysteries of quantum theory.

    “No one is sure what actually constitutes a measurement. Perhaps physicists can agree that someone with a Ph.D. wearing a white coat sitting in the lab of a famous university can make measurements. But what about somebody who really isn’t sure what they are doing? Is consciousness required? We don’t really know.”

    Authors on the paper in addition to Maris were former Brown postdoctoral researcher Wanchun Wei, graduate student Zhuolin Xie, and George Seidel, professor emeritus of physics.

    See the full article here.

    Welcome to Brown

    Rhode Island Hall: Rhode Island Hall’s classical exterior was recently renovated with a modern interiorRhode Island Hall: Rhode Island Hall’s classical exterior was recently renovated with a modern interior

    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

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  • richardmitnick 12:00 pm on October 24, 2014 Permalink | Reply
    Tags: , Charles Munger, , Physics,   

    From NYT: “Charles Munger, Warren Buffett’s Longtime Business Partner, Makes $65 Million Gift” 

    New York Times

    The New York Times

    October 24, 2014
    Michael J. de la Merced

    Charles T. Munger has been known for many things over his decades-long career, including longtime business partner of Warren E. Buffett; successful investor and lawyer; and plain-spoken commentator with a wide following.


    Now Mr. Munger, 90, can add another title to that list: deep-pocketed benefactor to the field of theoretical physics.

    He was expected to announce on Friday that he has donated $65 million to the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara. The gift — the largest in the school’s history — will go toward building a 61-bed residence for visitors to the institute, which brings together physicists for weeks at a time to exchange ideas.

    “U.C.S.B. has by far the most important program for visiting physicists in the world,” Mr. Munger said in a telephone interview. “Leading physicists routinely are coming to the school to talk to one another, create new stuff, cross-fertilize ideas.”

    UC Santa Barbara Campus

    The donation is the latest gift by Mr. Munger, a billionaire who has not been shy in giving away the wealth he has accumulated as vice chairman of Mr. Buffett’s Berkshire Hathaway to charitable causes.

    Though perhaps not as prominent a donor as his business partner, who cocreated the Giving Pledge campaign for the world’s richest people to commit their wealth to philanthropy, Mr. Munger has frequently donated big sums to schools like Stanford and the Harvard-Westlake School. (He has not signed on to the Giving Pledge campaign.)

    The biggest beneficiary of his largess thus far has been the University of Michigan, his alma mater. Last year alone, he gave $110 million worth of Berkshire shares — one of the biggest gifts in the university’s history — to create a new residence intended to help graduate students from different areas of study mingle and share ideas.

    That same idea of intellectual cross-pollination underpins the Kavli Institute, which over 35 years has established itself as a haven for theoretical physicists from around the world to meet and discuss potential new developments in their field.

    Funded primarily by the National Science Foundation, the institute has produced advances in the understanding of white dwarf stars, string theory and quantum computing.

    A former director of the institute, David J. Gross, shared in the 2004 Nobel Prize in Physics for work that shed new light on the fundamental force that binds together the atomic nucleus.

    “Away from day-to-day responsibilities, they are in a different mental state,” Lars Bildsten, the institute’s current director, said of the center’s visitors. “They’re more willing to wander intellectually.”

    To Mr. Munger, such interactions are crucial for the advancement of physics. He cited international conferences attended by the likes of [Albert]Einstein and Marie Curie.

    Mr. Munger himself did not study physics for very long, having taken a class at the California Institute of Technology while in the Army during World War II. But as an avid reader of scientific biography, he came to appreciate the importance of the field.

    And he praised the rise of the University of California, Santa Barbara, as a leading haven for physics, particularly given its status as a relatively young research institution.

    But while the Kavli Institute conducts various programs throughout the year for visiting scientists, it has long lacked a way for physicists to spend time outside of work hours during their stays. A permanent residence hall would allow them to mingle even more, in the hope of fostering additional eureka moments.

    “We want to make their hardest choice, ‘Which barbecue to go to?’ ” Mr. Bildsten joked.

    Though Mr. Munger has some ties to the University of California, Santa Barbara — a grandson is an alumnus — he was first introduced to the Kavli Institute through a friend who lives in Santa Barbara.

    During one of the pair’s numerous fishing trips, that friend, Glen Mitchel, asked the Berkshire vice chairman to help finance construction of a new residence. The university had already reserved a plot of land for the dormitory in case the institute raised the requisite funds.

    “It wasn’t a hard sell,” Mr. Munger said.

    “Physics is vitally important,” he added. “Everyone knows that.”

    See the full article here.

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  • richardmitnick 3:49 pm on October 17, 2014 Permalink | Reply
    Tags: , , , Physics   

    From ANL: “Protons hog the momentum in neutron-rich nuclei” 

    News from Argonne National Laboratory

    October 17, 2014
    Kandice Carter, Jefferson Lab Public Affairs, 757-269-7263, kcarter@jlab.org
    or Jared Sagoff, Argonne National Laboratory communications office, 630-252-5549, media@anl.gov.

    Like dancers swirling on the dance floor with bystanders looking on, protons and neutrons that have briefly paired up in the nucleus have higher-average momentum, leaving less for non-paired nucleons. Using data from nuclear physics experiments carried out at the Department of Energy’s Thomas Jefferson National Accelerator Facility, researchers have now shown for the first time that this phenomenon exists in nuclei heavier than carbon, including aluminum, iron and lead.

    Research has shown that protons and neutrons that have briefly paired up in the nucleus have higher-average momentum, which allows a greater fraction of the protons than neutrons to have high momentum in relatively neutron-rich nuclei, such as carbon, aluminum, iron and lead. This result is contrary to long-accepted theories large nuclei and has implications for ultra-cold atomic gas systems and neutron stars.

    The phenomenon also surprisingly allows a greater fraction of the protons than neutrons to have high momentum in these relatively neutron-rich nuclei, which is contrary to long-accepted theories of the nucleus and has implications for ultra-cold atomic gas systems and neutron stars. The results were published online by the journal Science, on the Science Express website.

    The research builds on earlier work featured in Science that found that protons and neutrons in light nuclei pair up briefly in the nucleus, a phenomenon called a short-range correlation. Nucleons prefer pairing up with nucleons of a different type (proton preferred neutrons to other protons) by 20 to 1, and nucleons involved in a short-range correlation carry higher momentum than unpaired ones.

    Using data from an experiment conducted in 2004, the researchers were able to identify high-momentum nucleons involved in short-range correlations in heavier nuclei. In that experiment, led by Argonne physicist Kawtar Hafidi, the Jefferson Lab Continuous Electron Beam Accelerator Facility produced a 5.01 GeV beam of electrons to probe the nuclei of carbon, aluminum, iron and lead. The outgoing electrons and high-momentum protons were measured.

    “We found this dominance of proton-neutron pairs in the nuclei we studied. What’s striking is this pair-dominance all the way to lead,” says Doug Higinbotham, a staff scientist at Jefferson Lab and a lead coauthor on the paper.

    Then the researchers compared the momenta of protons versus neutrons in these nuclei. According to the Pauli exclusion principle, certain like particles can’t have the same momentum state. So, if you have a bunch of neutrons together, some will have low momentum, and others will have high momentum; the more neutrons you have, the more high-momentum neutrons you would see, as they fill up higher and higher momentum states.

    But according to Higinbotham, that expected picture is not what the researchers found when they measured high-momentum protons in neutron-rich nuclei.

    “What this paper is saying is the reverse, that the protons actually have the higher-average momentum. And it’s because they’ve all paired up with neutrons,” Higinbotham says. “It’s like a dance with too many girls (neutrons) and only a few boys (protons). Those boys are dancing their little hearts out, because there aren’t very many of them. So the average proton momentum is going to be higher than the average neutron momentum, because it’s mostly the neutrons that are sitting there, doing nothing, with nothing to pair up with, except themselves.”

    Higinbotham notes that the neutrons may also pair up briefly with other neutrons in short-range correlations and protons with other protons. However, these like-particle brief pairings occur once for roughly every 20 unlike-particle brief pairings.

    Now, the researchers hope to extend these new findings to other, similar systems, such as the quarks in nucleons and atoms in cold gases. According to Or Hen, a graduate student at Tel Aviv University in Israel and the paper’s lead author, he and his colleagues are already reaching out to other researchers.

    “We expect that this will also happen in ultra-cold atomic gas systems. And we’re having meetings with those researchers. If they find the same phenomenon, then we can use the flexibility of their experimental systems to go to extreme cases of very hard-to-study nuclear systems, such as the large imbalances of protons and neutrons that you can find in neutron stars,” Or said.

    To further that goal, Misak Sargsian, a lead coauthor and professor at Florida International University, said he’s extending this work into his own theoretical calculations of neutron stars.

    “Think of a neutron star like it’s a huge nucleus, where you have ten times more neutrons than protons. The effect should be very, very profound for neutron stars. So this opens up a new direction for research,” Sargsian said.

    According to Lawrence Weinstein, a lead coauthor and eminent scholar and professor at Old Dominion University in Norfolk, Va., the scientists would also like to continue their studies of the pairs.

    “We’d like to measure a lot more aspects of how protons and neutrons pair up in nuclei. So we know not just protons prefer neutrons, but how are the pairs behaving, in detail,” he said.

    This new result was made possible by an initiative funded by a grant from the U.S. Department of Energy and led by Weinstein and Sargsian, as well as Mark Strikman, a distinguished professor at Penn State, and Sebastian Kuhn, a professor and eminent scholar at Old Dominion University. The data-mining initiative consisted of re-analyzing experimental data from completed experiments in an attempt to glean new information that previously had not been considered or was missed. A collaboration of more than 140 researchers from more than 40 institutions and nine countries contributed to the result. Researchers at two U.S. Department of Energy national labs, Jefferson Lab and Argonne National Lab, participated in the research.

    Argonne physicist Kawtar Hafidi led the experiment that first collected the data back in 2003. “That data was so unique that we’ve been able to extract all kinds of information on several different areas of nuclear physics since then,” she said. She chairs the group, the CEBAF Large Acceptance Spectrometer collaboration nuclear physics working group, that oversees the review and release of scientific results from the data taken by that experiment.

    “This is excellent work that helps validate our theoretical picture of nuclear structure,” said Robert Wiringa, an Argonne physicist whose theoretical work is cited in the paper.

    The paper was published online by the journal Science, at the Science Express web site, on Thursday, 16 October, 2014. See http://www.sciencexpress.org, and also http://www.aaas.org. Science and Science Express are published by the AAAS, the science society, the world’s largest general scientific organization.

    This work was supported by the U.S. Department of Energy’s Office of Science (Office of Nuclear Physics), the U.S. National Science Foundation, Israel Science Foundation, Chilean Comisión Nacional de Investigación Científica y Technológica, French Centre National de la Recherche Scientifique and Commissariat a l’Energie Atomique, French-American Cultural Exchange, Italian Istituto Nazionale di Fisica Nucleare, National Research Foundation of Korea and the U.K.’s Science and Technology Facilities Council. CEBAF is a DOE Office of Science User Facility.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus

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  • richardmitnick 2:41 pm on October 14, 2014 Permalink | Reply
    Tags: , , , Physics,   

    From BNL: “Unstoppable Magnetoresistance” 

    Brookhaven Lab

    October 14, 2014
    Tien Nguyen

    Mazhar Ali, a fifth-year graduate student in the laboratory of Bob Cava, the Russell Wellman Moore Professor of Chemistry at Princeton University, has spent his academic career discovering new superconductors, materials coveted for their ability to let electrons flow without resistance. While testing his latest candidate, the semimetal tungsten ditelluride (WTe2), he noticed a peculiar result.

    Ali applied a magnetic field to a sample of WTe2, one way to kill superconductivity if present, and saw that its resistance doubled. Intrigued, Ali worked with Jun Xiong, a student in the laboratory of Nai Phuan Ong, the Eugene Higgins Professor of Physics at Princeton, to re-measure the material’s magnetoresistance, which is the change in resistance as a material is exposed to stronger magnetic fields.

    Mazhar Ali (left) and Steven Flynn (right), co-authors on the Nature article
    Photo credit: C. Todd Reichart

    “They have unique capabilities at Brookhaven. One is that they can measure diffraction at 10 Kelvin (-441 °F).”
    — Bob Cava, Princeton University

    “He noticed the magnetoresistance kept going up and up and up—that never happens.” said Cava. The researchers then exposed WTe2 to a 60-tesla magnetic field, close to the strongest magnetic field mankind can create, and observed a magnetoresistance of 13 million percent. The material’s magnetoresistance displayed unlimited growth, making it the only known material without a saturation point. The results were published on September 14 in the journal Nature.

    Electronic information storage is dependent on the use of magnetic fields to switch between distinct resistivity values that correlate to either a one or a zero. The larger the magnetoresistance, the smaller the magnetic field needed to change from one state to another, Ali said. Today’s devices use layered materials with so-called “giant magnetoresistance,” with changes in resistance of 20,000 to 30,000 percent when a magnetic field is applied. “Colossal magnetoresistance” is close to 100,000 percent, so for a magnetoresistance percentage in the millions, the researchers hoped to coin a new term.

    Crystal Structure of WTe2. Image credit: Nature

    Their original choice was “ludicrous” magnetoresistance, which was inspired by “ludicrous speed,” the fictional form of fast-travel used in the comedy “Spaceballs.” They even included an acknowledgement to director Mel Brooks. After other lab members vetoed “ludicrous,” the researchers considered “titanic” before Nature editors ultimately steered them towards the term “large magnetoresistance.”

    Terminology aside, the fact remained that the magnetoresistance values were extraordinarily high, a phenomenon that might be understood through the structure of WTe2. To look at the structure with an electron microscope, the research team turned to Jing Tao, a researcher at Brookhaven National Laboratory.

    Jing Tao

    “Jing is a great microscopist. They have unique capabilities at Brookhaven,” Cava said. “One is that they can measure diffraction at 10 Kelvin (-441 °F). Not too many people on Earth can do that, but Jing can.”

    Electron microscopy experiments revealed the presence of tungsten dimers, paired tungsten atoms, arranged in chains responsible for the key distortion from the classic octahedral structure type. The research team proposed that WTe2 owes its lack of saturation to the nearly perfect balance of electrons and electron holes, which are empty docks for traveling electrons. Because of its structure, WTe2 only exhibits magnetoresistance when the magnetic field is applied in a certain direction. This could be very useful in scanners, where multiple WTe2 devices could be used to detect the position of magnetic fields, Ali said.

    “Aside from making devices from WTe2, the question to ask yourself as a scientist is: How can it be perfectly balanced, is there something more profound,” Cava said.

    See the full article here.

    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

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  • richardmitnick 4:42 pm on October 13, 2014 Permalink | Reply
    Tags: , , , Physics   

    From physicsworld: “Dark matter could light up giant mirror” 


    Oct 13, 2014
    Edwin Cartlidge

    A large metallic mirror previously used as a prototype for a cosmic-ray observatory will be reused by physicists in Germany to hunt for “hidden photons”. These exotic and hitherto unseen cousins of normal photons could account for some dark matter – the mysterious and invisible substance that appears to account for about 85% of the matter in the universe.

    Most dark-matter experiments try to detect weakly interacting massive particles (WIMPs), which are predicted by the theory of supersymmetry and interact with other matter only via the weak nuclear force and gravity. WIMP detectors aim to capture the tiny amounts of energy given off in collisions between the putative particles and atomic nuclei – usually in large detectors deep underground. However, about a quarter of a century has passed since the first such experiment started and not a single WIMP has been unambiguously detected.

    Supersymmetry standard model
    Standard Model of Super Symmetry

    Hidden photons are predicted in some extensions of the Standard Model of particle physics, and unlike WIMPs they would interact electromagnetically with normal matter. Hidden photons also have a very small mass, and are expected to oscillate into normal photons in a process similar to neutrino oscillation. Observing such oscillations relies on detectors that are sensitive to extremely small electromagnetic signals, and a number of these extremely difficult experiments have been built or proposed.

    Many different experiments

    “In the last few years, the interest in hidden photons has been growing,” says Jonathan Feng of the University of California, Irvine – partly because searches for other dark-matter candidates have “come up empty”. Also, physicists have realized that many different kinds of experiment can be built to try and detect hidden photons.

    Now, Babette Döbrich and colleagues at DESY in Hamburg, the Karlsruhe Institute for Technology and other institutes in Europe are using a portion of a spherical, metallic mirror to look for hidden photons. This was suggested in 2012 by physicists in Germany in a paper called Searching for WISPy Cold Dark Matter with a Dish Antenna. The scheme exploits the fact that hidden photons would interact with electrons – albeit feebly – and when they strike a conductor they would set the constituent electrons vibrating. These vibrations would result in normal photons being emitted at right angles to the conductor’s surface.

    A spherical mirror is ideal for detecting such light because the emitted photons would be concentrated at the sphere’s centre, whereas any background light bouncing off the mirror would pass through a focus midway between the sphere’s surface and centre. A receiver placed at the centre could then pick up the dark-matter-generated photons, if tuned to their frequency – which is related to the mass of the incoming hidden photons – with mirror and receiver shielded as much as possible from stray electromagnetic waves.

    Ideal mirror at hand

    Reflecting on dark matter: giant mirror will seek dark matter

    Fortunately for the team, an ideal mirror is at hand: a 13 m2 aluminium mirror used in tests during the construction of the Pierre Auger Observatory and located at the Karlsruhe Institute of Technology. Döbrich and co-workers have got together with several researchers from Karlsruhe, and the collaboration is now readying the mirror by adjusting the position of each of its 36 segments to minimize the spot size of the focused waves. They are also measuring background radiation within the shielded room that will house the experiment. As for receivers, the most likely initial option is a set of low-noise photomultiplier tubes for measurements of visible light, which corresponds to hidden-photon masses of about 1 eV/C2. Another obvious choice is a receiver for gigahertz radiation, which corresponds to masses less than 0.001 eV/C2; however, this latter set-up would require more shielding.

    The DESY/Karlsruhe experiment – provisionally named FUNK (Finding U(1)’s of a Novel Kind) – will not be the first to search for hidden photons. The CERN Resonant WISP Search (CROWS) at the CERN laboratory in Geneva, which has been running since 2011, looks for both hidden photons and other low-mass dark-matter particles, such as axions. Also looking is the Axion Dark Matter Experiment at the University of Washington in Seattle. Although, as its name suggests, this facility has been set up mainly to detect axions, it can nevertheless probe the existence of hidden photons down to very low interaction strengths. The advantage of FUNK over its rivals, says Döbrich, is that it will be able to operate across quite a broad range of frequencies – just how broad will depend on the availability of suitable electromagnetic detectors and the performance of the mirror.

    Fritz Caspers of CERN applauds FUNK’s “very nice” design, but has concerns about how difficult it will be in practice to shield the mirror from electromagnetic interference. “The devil is always in the detail,” he says. He also wonders why Döbrich and colleagues did not “go directly” to look for emitted radio-frequency radiation using a radio telescope, with a dish up to perhaps 100 m across, rather than the smaller version they will use. “You could easily find much bigger mirrors in the world,” he says. Döbrich points out that in terms of optical measurements, their mirror is a very good choice.

    The research is described in a preprint on arXiv.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
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  • richardmitnick 1:00 pm on October 7, 2014 Permalink | Reply
    Tags: , , , Physics, TRIUMF ARIEL   

    From Triumf: “E-Linac Produces First Beam” 

    Triumf Lab

    07 October 2014
    No Writer Credit

    On September 30th, TRIUMF’s newly constructed superconducting electron linear accelerator (e-linac) produced its first particle beam at an initial energy of 23 MeV. The cutting-edge accelerator technology was designed and built in cooperation with institutions and industry across the country. Acceleration of first beam through the complete e-linac system culminates a series of recent successes for the Advanced Rare Isotope Laboratory (ARIEL) project and sets ARIEL on its path forward.


    ARIEL is on track to become one of the most sophisticated rare-isotope facilities in the world. The successful completion of the project is a consequence of a remarkable collaboration between TRIUMF, Canadian industry, and 13 Canadian universities led by the University of Victoria. The project was jointly funded by the Government of British Columbia through the BC Knowledge Development Fund (BCKDF), the Government of Canada through the Canadian Foundation for Innovation (CFI), and the National Research Council Canada through TRIUMF and in-kind contributions.

    “This is a tremendous accomplishment for these scientists, their teams, and for British Columbia,” said Minister of Technology, Innovation and Citizens’ Services Andrew Wilkinson. “Through cutting-edge research and innovation – like ARIEL – British Columbia is set to become a global leader in the field of superconductors and rare-isotope research.”

    “This is a remarkable achievement,” said Dr. Gilles Patry, President and CEO of the CFI. “The technology developed at TRIUMF has the potential to open new avenues for a whole host of innovative products and applications in science and medicine that will benefit Canadians. Congratulations to the entire ARIEL and TRIUMF team!”

    ARIEL’s e-linac is composed of many complex systems––including superconducting radiofrequency (SRF) accelerator cavities––whose thousands of components must work in concert at extreme tolerances in order to deliver beam successfully.

    “It is breathtaking how quickly the e-linac came together! It’s a testament to the tremendous collaboration between TRIUMF, Canada’s universities, and our industrial partner, PAVAC Industries, all driven by the hard work and superb technical expertise of dedicated scientists and students here and abroad,” said Dr. Lia Merminga, TRIUMF Accelerator Division Head and co-leader of the ARIEL project.

    “Through our technology and knowledge transfer to industry, Canada is now one of only a handful of countries in the world with industrial capacity in SRF,” said Dr. Jonathan Bagger, TRIUMF Director. “PAVAC Industries is now in a position to sell leading-edge SRF accelerators to customers around the globe.”

    ARIEL is recognized internationally for its cutting-edge technical and scientific capabilities. The Variable Energy Cyclotron Centre (VECC) in Kolkata, India and TRIUMF have entered into a partnership to jointly develop accelerator and isotope production technologies for each facility.

    Thirteen institutions from across Canada contributed on building, installing, and commissioning the e-linac. Dr. Dean Karlen, Principal Investigator from the University of Victoria said, “In collaborating on this e-linac project, we developed a strong partnership with TRIUMF. The University of Victoria put forward the proposal to CFI and also provided oversight for the project. Within the Physics Department, a group of students and staff designed, built, and commissioned the system that examines the electron beam inside the accelerator. In addition, the e-linac project allowed the University to develop a graduate program in Accelerator Physics with TRIUMF.”

    “The ARIEL project continues to signal to the world that Canada is at the leading edge of accelerator physics and engineering,” said Dr. David Castle, Vice-President Research at the University of Victoria. “The remarkable success of this project has also brought many Canadian and international universities together in the spirit of true collaboration and intellectual inquiry.”

    The next phase of the ARIEL project will further expand the collaboration to 19 Canadian universities and five provincial governments. New partnerships will be created with industry, and greater opportunities will arise for the training of the next generation of scientists and engineers. Over the next five years, ARIEL will advance scientific and technical capabilities, will yield even greater societal and economic benefits for Canada, and will solidify TRIUMF as an international hub for cutting-edge rare-isotope research.

    For more information on ARIEL, please visit http://www.triumf.ca/ariel

    See the full article here.

    World Class Science at Triumf Lab, British Columbia, Canada
    Canada’s national laboratory for particle and nuclear physics
    Member Universities:
    University of Alberta, University of British Columbia, Carleton University, University of Guelph, University of Manitoba, Université de Montréal, Simon Fraser University,
    Queen’s University, University of Toronto, University of Victoria, York University. Not too shabby, eh?

    Associate Members:
    University of Calgary, McMaster University, University of Northern British Columbia, University of Regina, Saint Mary’s University, University of Winnipeg, How bad is that !!
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  • richardmitnick 2:43 pm on October 3, 2014 Permalink | Reply
    Tags: , , , , Physics   

    From BNL: “Brookhaven and the Daya Bay Neutrino Experiment” 

    Brookhaven Lab

    October 1, 2014
    Karen McNulty Walsh

    The Daya Bay Collaboration, an international group of scientists studying the subtle transformations of subatomic particles called neutrinos, is publishing its first results on the search for a so-called sterile neutrino, a possible new type of neutrino beyond the three known neutrino “flavors,” or types. The existence of this elusive particle, if proven, would have a profound impact on our understanding of the universe, and could impact the design of future neutrino experiments. The new results, appearing in the journal Physical Review Letters, show no evidence for sterile neutrinos in a previously unexplored mass range. Read the collaboration press release.

    Daya Bay
    Daya Bay
    The U.S. Department of Energy’s Brookhaven National Laboratory plays multiple roles in the Daya Bay experiment, ranging from management to data analysis. In addition to coordinating detector engineering and design efforts and developing software and analysis techniques, Brookhaven scientists perfected the “recipe” for a very special, chemically stable liquid that fills Daya Bay’s detectors and interacts with antineutrinos. This work at Daya Bay builds on a legacy of breakthrough neutrino research by Brookhaven Lab that has resulted in two Nobel Prizes in Physics.

    Members of the BNL team on the Daya Bay Neutrino Project include: (seated, from left) Penka Novakova, Laurie Littenberg, Steve Kettell, Ralph Brown, and Bob Hackenburg; (standing, from left) Zhe Wang, Chao Zhang, Jiajie Ling, David Jaffe, Brett Viren, Wanda Beriguete, Ron Gill, Mary Bishai, Richard Rosero, Sunej Hans, and Milind Diwan. Missing from the picture are: Donna Barci, Wai-Ting Chan, Chellis Chasman, Debbie Kerr, Hide Tanaka, Wei Tang, Xin Qian, Minfang Yeh, and Elizabeth Worcester.

    Comments from U.S. Daya Bay Chief Scientist Steve Kettell

    Steve Kettell

    This body of research is helping to unlock the secrets of the least understood constituents of matter—an important quest considering that neutrinos outnumber all other particle types with a billion neutrinos for every quark or electron.

    The fairly recent discovery that neutrinos have mass changes how we must think about the Standard Model of particle physics because it cannot be explained by that well-accepted description of all known particles and their interactions.

    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Understanding the details of neutrino mass could have huge implications for our understanding of how the universe evolved. And those details—including how neutrinos oscillate, or switch from one flavor to another, are the essence of the research at Daya Bay and a key to unlocking these mysteries.

    The unusual properties of the known neutrinos, particularly their unique mass properties compared to other particles in the Standard Model, give us good reason to suspect that the universe may be full of such neutral particles of other flavors, such as the sterile neutrino. These particles could potentially help account for a large portion of matter in the universe that we cannot detect directly, so called dark matter.

    Daya Bay has been an exciting experiment to work on. It has been exquisitely designed and built, enabling us to make several important discoveries (first result and new result) and to search for these particles. And while the latest study from Daya Bay did not detect evidence of sterile neutrinos, it did greatly narrow the range in which we need to search. We will continue to exploit this beautiful experiment to further explore and understand the properties of the mysterious neutrino.

    The existence of neutrino mass and mixing leads to further deep questions, in particular whether neutrinos are responsible for the dominance of matter over antimatter in the universe. With the first results from Daya Bay this question now seems answerable with the long-baseline neutrino project planned at DOE’s Fermi National Accelerator Laboratory. Brookhaven scientists identified this scientific opportunity and continue to lead the development of this project, which has now been endorsed by recent national advisory panels as the highest priority domestic project in fundamental particle physics.
    See the full article here.

    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

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  • richardmitnick 2:35 pm on September 30, 2014 Permalink | Reply
    Tags: , , , Physics   

    From physicsworld: “Japan seeks to splurge on big-science facilities” 


    Sep 26, 2014
    Dennis Normile

    Physics in Japan is set for a major boost after the education ministry asked for a massive 18% increase for its 2015 science and technology budget to take it to $11.1bn. Support for major facilities – including the SPring-8 synchrotron and the SACLA X-ray free-electron laser, both in Hyōgo Prefecture, and the Japan Proton Accelerator Research Complex (J-PARC) in Tokaimura – would rise 15.6% to $960m. The finance ministry, however, is likely to squeeze the requested amounts before the budget, which takes effect from next April, goes before the legislature in December.



    The money for SACLA and SPring-8 would mean the facilities could run for an additional 750 and 1000 hours, respectively, and also fund an upgrade at SACLA. At J-PARC, the cash would go on overall operations plus maintenance and safety upgrades. The ministry’s request also includes $11m to finish the Large-Scale Cryogenic Gravitational Wave Telescope (also known as KAGRA).


    Built in the Ikenoyama Mountain in Kamioka, KAGRA features two 3 km-long arms forming an “L” for the detector plus two access tunnels. Some 7.7 km of tunnels were completed earlier this year that will be used for the experiment. “[The budget allocation] would allow us to complete equipment development and installation,” says KAGRA project director Takaaki Kajita, who is based at the University of Tokyo’s Institute for Cosmic Ray Research in Kashiwa. The facility is expected to be complete by the end of next year and start operations in 2017.

    For ongoing international projects, the ministry is seeking $54m for Japan’s contribution to the Thirty Meter Telescope being built on Mauna Kea in Hawaii, as well as $260m for ITER, the experimental fusion reactor currently under construction in Cadarache, France.

    TMT Schematic

    ITER Tokamak
    ITER Tokamak

    The ministry also aims to spend $1m to continue studies for the proposed International Linear Collider (ILC), which Japan has expressed an interest in hosting. This year the government set up a committee to investigate the scientific case for the facility, with sub-committees looking at technical issues and cost. Satoru Yamashita, a physicist at the University of Tokyo who chairs Japan’s ILC Strategy Council, says the country took a step towards international support for the $10bn project with initial political-level discussions with the US in July. “There is still a lot to do,” adds Yamashita.

    LC Linear Collider

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
    IOP Institute of Physics

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  • richardmitnick 3:43 pm on September 29, 2014 Permalink | Reply
    Tags: , Physics,   

    From Scientific American: “Einstein’s “Time Dilation” Prediction Verified “ 

    Scientific American

    Scientific American

    Sep 22, 2014
    By Alexandra Witze and Nature magazine

    Experiments at a particle accelerator have confirmed the “time dilation” effect predicted by Albert Einstein’s special theory of relativity

    Physicists have verified a key prediction of Albert Einstein’s special theory of relativity with unprecedented accuracy. Experiments at a particle accelerator in Germany confirm that time moves slower for a moving clock than for a stationary one.

    To test the time-dilation effect, physicists need to compare two clocks — one that is stationary and one that moves.
    Credit: Nick via flickr

    The work is the most stringent test yet of this ‘time-dilation’ effect, which Einstein predicted. One of the consequences of this effect is that a person travelling in a high-speed rocket would age more slowly than people back on Earth.

    Few scientists doubt that Einstein was right. But the mathematics describing the time-dilation effect are “fundamental to all physical theories”, says Thomas Udem, a physicist at the Max Planck Institute for Quantum Optics in Garching, Germany, who was not involved in the research. “It is of utmost importance to verify it with the best possible accuracy.”

    The paper was published on September 16 in Physical Review Letters. It is the culmination of 15 years of work by an international group of collaborators including Nobel laureate Theodor Hänsch, director of the Max Planck optics institute.

    To test the time-dilation effect, physicists need to compare two clocks — one that is stationary and one that moves. To do this, the researchers used the Experimental Storage Ring, where high-speed particles are stored and studied at the GSI Helmholtz Centre for heavy-ion research in Darmstadt, Germany.

    The scientists made the moving clock by accelerating lithium ions to one-third the speed of light. Then they measured a set of transitions within the lithium as electrons hopped between various energy levels. The frequency of the transitions served as the ‘ticking’ of the clock. Transitions within lithium ions that were not moving served as the stationary clock.

    The researchers measured the time-dilation effect more precisely than in any previous study, including one published in 2007 by the same research group. “It’s nearly five times better than our old result, and 50 to 100 times better than any other method used by other people to measure relativistic time dilation,” says co-author Gerald Gwinner, a physicist at the University of Manitoba in Winnipeg, Canada.

    Understanding time dilation has practical implications as well, he notes. Global Positioning System (GPS) satellites are essentially clocks in orbit, and GPS software has to account for tiny time shifts when analysing navigational information. The European Space Agency plans to test time dilation in space when it launches its Atomic Clock Ensemble in Space (ACES) experiment to the International Space Station in 2016.

    The speed of fast-moving ions means that accelerator experiments can test time dilation more precisely than experiments in Earth orbit, says Matthew Mewes, a physicist at California Polytechnic State University in San Luis Obispo, who is not part of the team. “It’s important to look wherever we can and push the technology whenever possible,” he says.

    But the research group is dismantling its longtime collaboration, as there is no larger accelerator they can go to for more powerful tests. “It’s been many hours in basements, in shielded rooms with noisy equipment, and in the end you get one number,” says Gwinner. “We’ve been exchanging a bunch of nostalgic e-mail.”

    See the full article here.

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

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  • richardmitnick 3:11 pm on September 28, 2014 Permalink | Reply
    Tags: , , Physics,   

    From Scientific American: “Weak Nuclear Force Shown to Give Asymmetry to Biochemistry of Life” 

    Scientific American

    Scientific American

    Sep 26, 2014
    Elizabeth Gibney and Nature magazine

    Physicists have found hints that the asymmetry of life — the fact that most biochemical molecules are ‘left-handed’ or ‘right-handed’ — could have been caused by electrons from nuclear decay in the early days of evolution. In an experiment that took 13 years to perfect, the researchers have found that these electrons tend to destroy certain organic molecules slightly more often than they destroy their mirror images.

    Life is made largely of molecules that are different than their mirror images.
    Credit: Brett Weinstein via Flickr

    Many organic molecules, including glucose and most biological amino acids, are ‘chiral’. This means that they are different than their mirror-image molecules, just like a left and a right glove are. Moreover, in such cases life tends to consistently use one of the possible versions — for example, the DNA double helix in its standard form always twists like a right-handed screw. But the reason for this preference has long remained a mystery.

    Many scientists think that the choice was simply down to chance. Perhaps, in one of the warm little ponds filled with organic chemicals where life arose, a statistical fluke generated a small imbalance in the relative amounts of the two versions of one chemical. This small imbalance could have then amplified over time.

    But an asymmetry in the laws of nature has led others to wonder whether some physical phenomenon could have tipped the balance during the early stages of life. The weak nuclear force, which is involved in nuclear decay, is the only force of nature known to have a handedness preference: electrons created in the subatomic process known as β decay are always ‘left-handed’. This means that their spin — a quantum property analogous to the magnetization of a bar magnet — is always opposite in direction to the electron’s motion.

    In 1967, biochemist Frederic Vester and environmental scientist Tilo Ulbricht proposed that photons generated by these so-called spin-polarized electrons — which are produced in the decay of radioactive materials or of cosmic-ray particles in the atmosphere — could have destroyed more of one kind of molecule than another, creating the imbalance. Some physicists have since suggested that the electrons themselves might be the source of the asymmetry.

    But the hunt to find chemical processes through which electrons or photons could preferentially destroy one version of a molecule over its mirror image has seen little success. Many claims have proven impossible to reproduce. The few experiments in which electron handedness produced a chiral imbalance could not identify the chemical process behind it, says Timothy Gay, a chemical physicist at the University of Nebraska–Lincoln and a co-author of the latest study. But pinpointing a chemical reaction would help scientists to rule out some candidate causes of the process and to better understand the physics that underlie it, he adds.

    Taking it slow

    Gay and Joan Dreiling, a physicist also at the University of Nebraska–Lincoln, fired low-energy, spin-polarized electrons at a gas of bromocamphor, an organic compound used in some parts of the world as a sedative. In the resulting reaction, some electrons were captured by the molecules, which then were kicked into an excited state. The molecules then fell apart, producing bromide ions and other highly reactive compounds. By measuring the flow of ions produced, the researchers could see how often the reaction occurred for each handedness of electron.

    The researchers found that left-handed bromocamphor was just slightly more likely to react with right-handed electrons than with left-handed ones. The converse was true when they used right-handed bromocamphor molecules. At the lowest energies, the direction of the preference flipped, causing an opposite asymmetry.

    In all cases the asymmetry was tiny, but consistent, like flipping a not-quite-fair coin. “The scale of the asymmetry is as though we flip 20,000 coins again and again, and on average, 10,003 of them land on heads while 9,997 land on tails,” says Dreiling.

    The low speed of the electrons was the key to why the experiment finally worked after so many years, Dreiling says. “The interaction takes longer, and it was that insight, I think, that led to our success,” she says.

    The test offers an explanation for how a chiral excess could — at least in principle — arise, Gay says. The research was published in Physical Review Letters on 12 September.

    The idea that spin-polarized electrons could transmit their asymmetry to organic molecules is attractive, says Uwe Meierhenrich, an analytical chemist at the University of Nice Sophia Antipolis in France. The tiny effect that Gay and Dreiling observed would have to be amplified to affect the chemistry of life as a whole — but there are known mechanisms for such amplification, he says. “From my point of view, the main question does not concern the amplification processes, but the first chiral-symmetry breaking,” he says.

    Meierhenrich says that he would like to see the experiment repeated with chiral molecules that are relevant to the origin of life, such as amino acids, to see whether the left-handed electrons produce the same effect.

    Primordial cause

    Even if spin-polarized electrons caused life to become chirally selective, it is still unclear what would have produced those electrons in the first place. Sources of β particles include phosphorus-32 decaying into sulphur-32, or the decay of muons, elementary particles produced at the end of a chain of decays that begin when cosmic ray particles hit the atmosphere. In both cases, the electrons would have been travelling much faster than in Gay’s reaction, but he says that it is possible for electrons to slow down without losing their chirality.

    Slower-moving, left-handed electrons are produced in other ways than via β decay, says Richard Rosenberg, a chemist at the Argonne National Laboratory in Illinois. In 2008 he and his team showed that irradiating a layer of magnetized iron with X-rays could also produce a chirality preference. Chirality could therefore also have been created in molecules stuck to magnetized particles in a dust cloud or comet, he says.

    Gay and his colleagues plan to look at similar reactions with other varieties of camphor molecules to understand how the spin of an electron dictates which of two chiral molecules it prefers.

    The interaction of left-handed electrons with organic molecules is not the only potential explanation for the chiral asymmetry of life.. Meierhenrich favors an alternative — the circularly polarized light that is produced by the scattering of light in the atmosphere and in neutron stars. In 2011, Meierhenrich and colleages showed that such light could transfer its handedness to amino acids.

    But even demonstrating how a common physical phenomenon would have favoured left-handed amino acids over right-handed ones would not tell us that this was how life evolved, adds Laurence Barron, a chemist at the University of Glasgow, UK. “There are no clinchers. We may never know.”

    See the full article here.

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

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