News this Week

Science  05 Aug 2011:
Vol. 333, Issue 6043, pp. 680

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  1. Around the World

    1 - Washington, D.C., and New York City
    Courts Back Gene Patents, Human Embryonic Stem Cells
    2 - Osaka, Japan
    Marine Census Wins Environmental Prize
    3 - London
    U.K. Primate Research Is—Generally—Justified
    4 - Doha, Qatar
    Hidden HIV in Mideast Men
    5 - Paris
    Anti-Fraud Agency Puts Spotlight on E.U.'s Drug Watchdog

    Washington, D.C., and New York City

    Courts Back Gene Patents, Human Embryonic Stem Cells

    Perhaps ending a long-running legal battle that has disrupted human embryonic stem cell research in the United States, a federal judge last week threw out a lawsuit seeking to stop government funding of such studies by the National Institutes of Health (see p. 683).

    And biotech companies got a break 29 July when a U.S. appeals court ruled that genes can be patented, reversing a lower court's decision last year, which found that genes cannot be patented because they are “products of nature.”

    The patent case was prompted by a suit involving Myriad Genetics of Salt Lake City, Utah. The ruling stated that Myriad's basic patents on sequences of the genes BRCA1 and BRCA2 were valid because they applied to “isolated DNA” that has been manipulated chemically, producing a molecule that is markedly different from that in the body.

    However, on narrower grounds the court rejected five of Myriad's claims on ways to look at the genes' mutations, such as those that carry a high risk for breast or ovarian cancer.

    Osaka, Japan

    Marine Census Wins Environmental Prize

    Cold jelly.

    An Arctic jellyfish found by CoML.


    A 10-year, $650 million effort to assess past and present biodiversity in the sea and determine the distribution of marine organisms (Science, 6 August 2010, p. 622) has captured Japan's International Cosmos Prize. The prize is a $510,000 environmental award given to commemorate the theme of a 1990 Japanese flower and garden exposition: the harmonious coexistence between nature and mankind. Given to the Scientific Steering Committee of the Census of Marine Life (CoML), the award usually goes to individuals; the only other group so honored was the Charles Darwin Research Station in the Galápagos in 2002. “Usually recognition comes with a considerable time lag,” notes CoML committee member Jesse Ausubel. “To have something like this happen less than a year after the completion of the first census is just thrilling.”


    U.K. Primate Research Is—Generally—Justified

    Research using monkeys, baboons, and other nonhuman primates in the United Kingdom produces results that justify the animal welfare costs, a new comprehensive review concludes. But scientists should be careful not to exaggerate the medical impact of such research, the review panel said.

    Common marmosets are often used in nonhuman primate research.


    Animal research on nonhuman primates (NHPs) is a sensitive issue in the United Kingdom. In response to scientific and public concerns, four research organizations—the Biotechnology and Biological Sciences Research Council, the Medical Research Council, the National Centre for the Replacement, Refinement and Reduction of Animals in Research, and the Wellcome Trust—commissioned the new review, which asked all 72 researchers who had received government funding for research with NHPs between 1997 and 2006 to answer a questionnaire about the outcomes of their work.

    The panel found that most research was justified in its use of NHPs and led to peer-reviewed publications. “In general, primate research is productive and high-quality,” panel chair Patrick Bateson, a professor emeritus at the University of Cambridge, said at a press briefing in London 27 July. However, he added, the panel was concerned that “it was actually quite difficult to identify grants that had substantial medical benefits.” The panel was also concerned about the handful of projects that didn't lead to any papers. Even if experiments produce negative results, the panel says, “researchers using NHPs have a moral obligation to publish” their work to keep others from repeating it unnecessarily.

    Doha, Qatar

    Hidden HIV in Mideast Men

    In most of the Middle East and North Africa, men who have sex with men (MSM) face severe stigma and harsh laws, creating a hidden population that HIV/AIDS researchers have difficulty reaching. A comprehensive review of HIV's spread among MSM in the region reveals several hidden epidemics affecting as many as 28% of members of some groups.

    Epidemiologists Ghina Mumtaz and Laith Abu-Raddad, both of Weill Cornell Medical College in Qatar, led the study, which spent the past 8 years gleaning the highest quality reports from scientific publications, government documents, and surveys by nongovernmental organizations. “The data suggest these epidemics are recent,” says Mumtaz. As the researchers detail in the August issue of PLoS Medicine, about 2% to 3% of males in the region have anal sex with men, which is similar to global levels. In most locales, fewer than 25% of MSM reported consistent use of condoms, and exchanging sex for money was common, as was sex with females. While MSM generally knew about HIV, many did not think they were at any risk of becoming infected.


    Anti-Fraud Agency Puts Spotlight on E.U.'s Drug Watchdog

    The European Anti-Fraud Office is investigating alleged conflicts of interest at the European Medicines Agency (EMA) in London. Michèle Rivasi, a French Member of the European Parliament for the party Europe Ecologie Les Verts, says the inquiry was triggered by her pressure to investigate EMA's role in a scandal involving the French antidiabetic drug Mediator.

    Mediator was widely prescribed in France as a weight-loss drug for nondiabetics, despite warnings that it caused heart valve problems, until it was banned in November 2009. Now, the drug is estimated to have caused between 500 and 2000 deaths. Rivasi claims that EMA should have intervened, for instance when Italy and Spain pulled the drug from the market in 1998, and that possible conflicts of interest among its experts may have prevented it from doing so.

    EMA, created to harmonize drug regulation systems the European Union, says it has done nothing wrong. It can recommend banning drugs only when asked by a national government, says a spokesperson, and EMA acted swiftly when France asked it for an opinion on Mediator in 2009.

  2. Newsmakers

    Polar Bear Researcher's Suspension Still Mysterious


    Prominent polar bear researcher Charles Monnett was suspended by his employer, the U.S. Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), on 18 July, pending an Inspector General's investigation that an employee advocacy group labeled a politically motivated “witch hunt.”

    Public disclosure of the suspension last week ignited a firestorm: Climate change skeptics speculated about scientific misconduct in regard to Monnett's polar bear work, while Public Employees for Environmental Responsibility (PEER), which filed a complaint with the U.S. Department of the Interior (DOI) on Monnett's behalf, suggested the investigation arose because Monnett's research threatens the government's ability to drill in the Arctic. PEER noted that in February, a DOI inspector interviewed Monnett about his 2006 paper in Polar Biology, stating that the office had received “allegations of scientific misconduct.”

    But on 29 July, in an e-mail sent to BOEMRE's Alaska regional office employees, BOEMRE Director Michael Bromwich stated that the suspension was not politically motivated and was unrelated to questions about Monnett's scientific integrity. PEER also released a 29 July letter from DOI to Monnett indicating the investigation is related to the scientist's management of an ongoing polar bear tracking study.


    John Marburger (1941–2011)



    John Marburger, a physicist and science adviser to President George W. Bush, died last week of cancer at the age of 70. Science advocates say that their respect for the man far exceeds any criticism of his boss.

    “What a wonderful career he had, as president of Stony Brook University and then director of Brookhaven National Laboratory before being named science adviser,” says Sherwood Boehlert, a fellow New Yorker and longtime Republican congressman who chaired the House of Representatives science committee during part of Marburger's record 8-year tenure as head of the White House Office of Science and Technology Policy. “The challenge he faced was serving a president who didn't really want much scientific advice, and who let politics dictate the direction of his science policy.”

    Marburger's most lasting legacy may be as midwife to the science of science policy. The emerging field looks at factors that shape a nation's ability to foster innovation and to reap the benefits from it, from tax and immigration policies to training the next generation of scientists and funding their research adequately. Marburger also defended the value of international scientific exchanges after the September 2001 terrorist attacks, when many politicians demanded curtailing the free flow of people and ideas.

  3. Random Sample

    Dawn Spies a Messed-Up Vesta


    Two weeks after settling into orbit around Vesta, the ion-propelled Dawn spacecraft is returning stunning images of the 530-kilometer-wide asteroid. And boy is it in rough shape. An image presented 1 August at a NASA press conference is the first whole-asteroid portrait returned from a distance of 5200 kilometers. The broad, relatively smooth expanse covering much of Vesta in this view is part of a 460-kilometer-wide crater formed after the impact of an 80-kilometer asteroid nearly shattered Vesta. Having been created relatively recently in solar system history, this impact basin has accumulated fewer of the smaller craters that roughen the surface to the north (top of image). More mysteriously, the region in the north is banded by parallel grooves running around Vesta's equatorial region. Planetary scientists modeling a huge impact on Vesta had warned that rocky debris could pile up in some odd shapes, but nothing like this showed up in their models.

    They Said It

    “Does it go, you know, anywhere close to the climate-change debate that's under way here on Earth? I mean, if the moon had erupting volcanoes … it's not as if we've been up there burning fossil fuels.”

    —Fox News anchor Jon Scott, asking Bill Nye the Science Guy about the significance of the Lunar Reconnaissance Orbiter's discovery of 800-million-year-old extinct volcanoes on the moon.

    Australia and Africa: Arguing Over Acacia


    Every 6 years, when the International Botanical Congress meets, it tackles a backlog of problems related to the naming of plants. At the Congress in Melbourne, Australia, in July, one longstanding debate finally got closure: who gets the acacia.

    To two different continents, the acacia is more than just a tree—it's an icon: the flat-topped thorn trees silhouetted against a red African sky; the golden wattle of Australia, whose green and gold colors inspire the garb of the country's Olympic athletes. For hundreds of years, since Swedish botanist Carl Linnaeus first described the type species of the genus Acacia in Africa in 1773, both continents could lay claim to acacia trees. But in the past 30 years, anatomical and genetic analyses demonstrated that Australian and African acacias do not belong in the same genus at all.

    So which trees—Australian or African—should be known as actual Acacia? Africa has prior claim since the first type species, Acacia nilotica, was found there, but Australia has the overwhelming majority of species: more than 1000, compared with Africa's 80. The issue was seemingly resolved at the 2005 botanical congress in Vienna, when the delegates decided that the acacia would belong to Australia. But another 6 years of debate ensued.

    The debate drew to a close when delegates to the 2011 botanical congress voted to uphold the 2005 decision. Australia's acacias will retain the genus name, and the new type species will be the Australian Acacia penninervis. African species would be assigned to the genus Vachellia.

    “This closes a difficult chapter in international botany,” says Kevin Thiele, a botanist from the Western Australian Herbarium in Kensington. “The vote was very clear and supported by a cross-section of the international community, not just Australians.”

    By the Numbers

    42,000 — Number of children in the world that die of celiac disease, according to a PLoS ONE study.

    $917 billion — Total proposed cuts over 10 years in U.S. discretionary spending (⅝ from domestic and ⅜ from defense programs) under this week's deficit-reduction agreement. President Barack Obama says there's still room for “job-creating investments in things like education and research.”

  4. Science Education

    Climate Change Sparks Battles in Classroom

    1. Sara Reardon

    The U.S. political debate over climate change is seeping into K-12 science classrooms, and teachers are feeling the heat.

    Growth potential.

    Students gather acorns for a middle school science project.


    This Spring, when the science department of Los Alamitos High School in southern California proposed an advanced class in environmental science, members of the elected school board for the small district in Orange County thought the course was a great idea. Then they read the syllabus and saw a mention of climate change.

    The topic, the board decided, is a “controversial issue.” Its next step was a new policy requiring teachers to explain to the school board how they are handling such topics in class in a “balanced” fashion. And the new environmental science course, which starts this fall, will be the first affected.

    Local teachers immediately deplored the board's actions. “It's very difficult when we, as science teachers, are just trying to present scientific facts,” says Kathryn Currie, head of the high school's science department. And science educators around the country say such attacks are becoming all too familiar. They see climate science now joining evolution as an inviting target for those who accuse “liberal” teachers of forcing their “beliefs” upon a captive audience of impressionable children.

    “Evolution is still the big one, but climate change is catching up,” says Roberta Johnson, executive director of the National Earth Science Teachers Association (NESTA) in Boulder, Colorado. An informal survey this spring of 800 NESTA members (see word cloud) found that climate change was second only to evolution in triggering protests from parents and school administrators. One teacher reported being told by school administrators not to teach climate change after a parent threatened to come to class and make a scene. Online message boards for science teachers tell similar tales.

    Hot topic.

    Teachers can bone up on climate science in workshops and classes.


    Unlike those biology teachers who have borne the brunt of the century-long assault on evolution, however, today's earth science teachers won't have the protection of the First Amendment's language about religion if climate change deniers decide to take their cause to court. But the teachers feel their arguments are equally compelling: Science courses should reflect the best scientific knowledge of the day, and offering opposing views amounts to teaching poor science.

    Most science teachers don't relish having to engage this latest threat to their profession. “They want to teach the science,” says Susan Buhr, education director at the Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder. “They're struggling to be on top of the science in the first place.”

    CIRES and NESTA offer workshops and online resources for educators seeking more information on climate change. But teachers also say that they resent devoting any of their precious classroom time to a discussion of an alleged “controversy.” And they believe that politics has no place in a science classroom.

    Even so, some are being dragged against their will into a conflict they fear could turn ugly. “There seems to be a lynch-mob hate against any teacher trying to teach climate change,” says Andrew Milbauer, an environmental sciences teacher at Conserve School, a private boarding school in Land O'Lakes, Wisconsin.

    Milbauer felt that wrath after receiving an invitation to participate in a public debate about climate change. The event, put on last year by Tea Party activists, proposed to pit high school teachers against professors and climate change deniers David Legates and Willie Soon in front of students from 200 high schools. Organizers said the format was designed “to expand knowledge of the global warming debate to the youth of our state.” When Milbauer and his colleagues declined to participate, organizer Kim Simac complained to the local papers about their “suspicious” behavior. Milbauer corresponded for a time on the organization's blog until Simac wrote that Milbauer, “in his role as science teacher, is passing on to our youth this monstrous hoax as being the gospel truth.”

    Milbauer regards the episode as an unfortunate but telling example of misguided science and uses it in class discussions. “I explain this is the trap the [other side] is building,” he says.

    Some teachers would disagree, however. In comments in the NESTA survey, a handful of teachers called climate change “just a theory like evolution” or said they firmly believed that opposing views should be presented with equal weight.

    Sowing confusion

    Given the ongoing and noisy national debate over climate change, it's not surprising that those disagreements are seeping into K-12 schools, too. Science educators are scrambling to figure out how to deliver top-quality instruction without being sucked into the maelstrom. The issue is acute in Louisiana, which enacted a law in 2008 that lists climate change along with evolution as “controversial” subjects that teachers and students alike can challenge in the classroom without fear of reprisal.

    A hotter climate?

    The phrase “climate change” came up often when NESTA asked its teacher members what classroom concepts trigger outside concerns.


    When a state law suggests that established scientific theories are controversial, says Ian Binns, a science education researcher at Louisiana State University in Baton Rouge, “it tells our students and teachers that there are problems that there aren't.” That ambiguity, he and others fear, can distort a student's understanding of the nature of scientific inquiry. “Science is not about providing balance to every viewpoint that's out there,” says Joshua Rosenau of the National Center for Science Education, a nonprofit organization in Oakland, California, that has begun to monitor controversies regarding climate change in addition to battles over evolution. To Rosenau, staging debates over science in schools or on the floors of Congress “is madness.”

    In Los Alamitos, the course will follow the curriculum laid out by the nonprofit College Board for its Advanced Placement (AP) course in environmental science, which presents the scientific evidence for climate change. This curriculum, which prepares students to take an end-of-year test for college credit, is what irritated Jeffrey Barke, a Los Alamitos school board member and physician who led the push to revise the district's policies after learning about the course. Barke has spoken publicly about his concern that “liberal faculty” members would use the course to present global warming as “dogma.”

    Science department head Currie criticizes the board's new policy and feels that it may confuse students when they answer multiple-choice questions relating to climate change on the final AP exam. “When a kid comes across that on the AP test, what are they supposed to bubble?” she asks. “The fact, or [Barke's] belief that it's not a fact?” The school board, however, has said that the new policy is simply a way to prevent political bias from entering the classroom.

    Currie and her colleagues are spending the summer working up a lesson plan for the new course, but she isn't sure what will satisfy the board. “I'm going to fight for scientific facts being presented in the classroom,” she says. “I want to keep politics out.”

    Arming for battle

    The extent to which politics is affecting geoscience courses around the country is hard to measure, Rosenau says: “Just like with evolution, it's difficult to know what a given teacher in a given classroom is teaching.”

    To improve the quality of that instruction, both CIRES and NESTA are trying to put up-to-date, data-rich climate science materials into the hands of teachers and students to supplement textbooks. They're not the only ones; even government agencies such as the National Oceanic and Atmospheric Administration, spurred by language in the 2007 America COMPETES Act about their role in improving science education, have beefed up their teacher training programs.

    But it's not enough to say that “you just need to teach people more,” Rosenau says. Teachers also have to learn how to defend themselves against parents or administrators wearing “ideological blinders,” he says. CIRES has analyzed the strategies that teachers used in the creationism debates and repurposed them for discussions about climate change. That includes citing state science standards—30 states include climate science in their description of what should be taught—and enlisting the support of administrators before tackling the subject in class.

    Those who have taught geoscience or environmental science may feel more confident than colleagues who teach general physical science in managing a classroom discussion. Parents and students trying to poke holes in what they are being taught often “can't articulate what the opposing view even is,” says Karen Lionberger, director of curriculum and content development for AP Environmental Science in Duluth, Georgia.

    Of course, some attacks on climate change come from well-heeled sources. In 2009, the Heartland Institute, which has received significant funding from Exxon-Mobil, expanded its audience beyond teachers and students with a pamphlet, called The Skeptic's Handbook, mailed to the presidents of the country's 14,000 public school boards.

    Heartland Institute senior fellow James Taylor, who sent out the pamphlet, says the underlying message is that educators need “to understand that there is quite a bit that remains to be learned” about climate change. Taylor also applauds the actions of the Los Alamitos school board, saying that “if the science is unsettled on any topic, of course you should present all points of view.”

    The AP course itself doesn't take a position on the issue, Lionberger says. The handful of multiple-choice questions on the final exam relating to climate change are not “slanted in any way,” she says, and none explicitly asks whether climate change is occurring. But because AP courses can be taken for college credit, she says, “we're going to follow what colleges and universities are doing” by teaching students about the factors that contribute to climate change and its effects on the planet. Although researchers are always adding to that pool of knowledge, she says “for now, we will fall on the side of consensus science.”

  5. Physics

    Furtive Approach Rolls Back the Limits of Quantum Uncertainty

    1. Adrian Cho

    You cannot measure a quantum particle without disturbing it. Or can you? Weird "weak measurements" are opening new vistas in quantum physics.


    Theorists Yakir Aharonov (left) and Lev Vaidman invented weak measurements.


    If you know only one bit of quantum mechanics, it's likely this: You cannot make measurements on a tiny thing like an electron or photon without disturbing it. That rule of thumb puts the famous uncertainty principle into practice. For example, you can't know both exactly where an electron is and how fast it's moving, because measuring its position gives the particle a random kick that renders its momentum unknown. But does the rule always hold? Perhaps not.

    Twenty-three years ago, three theorists invented a scheme that, they predicted, would enable experimenters to make “weak measurements” that do not disturb a quantum object. That idea flies in the face of the standard quantum theory, and for decades it remained a controversial sidelight little noticed by most physicists. But lately, experimenters have used weak measurements to produce a variety of surprising results. “The whole idea was so strange that people tried to pretend it didn't exist,” says Sandu Popescu, a theorist at the University of Bristol in the United Kingdom. “But in the past couple of years it's become appreciated.”

    Weak measurements are surprisingly powerful. Researchers have used them to make measurements with mind-boggling precision, to resolve apparent paradoxes posed by quantum mechanics, and even to probe things previously thought impossible to probe directly, such as the quantum wave, or “wave function,” that describes a particle. Nothing in the protocol of weak measurement breaks the rules of quantum mechanics. However, the scheme provides a way to wring more information from the theory and to sidestep some of the prohibitions drilled into the heads of physics students. “We're all trying to look behind the complex mathematical structure of quantum mechanics to understand more fully what we can measure,” says Aephraim Steinberg, an experimenter at the University of Toronto in Canada. “It may sound crazy if you've learned too much quantum mechanics.”

    However, weak measurements themselves can be as mind-bending as other aspects of quantum mechanics. For example, they provide self-consistent explanations of paradoxical experiments, but those explanations rely on negative probabilities, a concept that many physicists find unpalatable. “People aren't sure how to interpret the weak measurement,” says Jeff Lundeen, a physicist at the Canadian National Research Council in Ottawa. “What does it mean?”

    How to make a weak measurement

    Even before weak measurement came along, the quantum realm was plenty weird. For example, your car can sit in only one parking lot at a time, but an atom or other quantum particle can be in two places at once or spin in opposite directions simultaneously. You can't observe that bizarre behavior directly, however. Like a hammer, a standard measurement squashes a delicate two-ways-at-once state and leaves the tiny object in either one state or the other.

    Suppose you want to measure the spin of silver atoms. Quantum theory tells you that each silver atom has exactly half of a fundamental amount, or quantum, of spin. And the atom's axis of rotation can point in any direction, like a gyroscope's. To measure that direction, you need to link the spin to something else that will act as a “pointer,” like the one on a dial. For example, you can “couple” an atom's spin to its motion by running the atom through a magnetic field whose strength varies from place to place. The field will tug the atom in one direction or another depending on which way it is spinning. So if you shoot a beam of atoms that are all spinning the same way through such a magnetic field, the beam's deflection should serve as the pointer to reveal the spin.

    But if you do the experiment, that's not what happens. Instead, the magnetic field splits the beam in two (see figure, below). What's going on here?

    You've run headlong into quantum weirdness. Quantum theory states that each atom can spin in opposite directions at once—its axis pointing, say, up and down. Not only that, but when the atom is spinning in any arbitrary direction, its “quantum state” can be described as a specific mathematical combination of any two opposite directions. For instance, spinning on an axis pointing to the right equals the 50-50 combination “up plus down,” and spinning to the left equals “up minus down.” A strong vertical magnet randomly “collapses” that both-ways quantum state, leaving each atom spinning either up or down and deflecting it accordingly. The intensities of the two beams then reveal the amounts of up and down in the atoms' quantum state.


    A standard measurement (top), a nonmeasurement (middle), and a weak measurement of a beam of spinning atoms (inset, interfering up [red] and down [blue] quantum waves).


    Such a “strong” measurement obliterates the original up-and-down state, however. To avoid that disturbance, an experimenter would have to weaken the magnetic field until it merely spreads the beam and ever so slightly deflects it. But the less-intrusive scheme reveals little about the atoms, and for decades physicists considered it a nonmeasurement.

    Then, in 1988 theorists Lev Vaidman and Yakir Aharonov, both now at Tel Aviv University in Israel, and David Albert, now at Columbia University, devised a way to milk information from such a feeble measurement. “If you do a measurement, you believe that the more information you get, the bigger the disturbance,” Aharonov says. “But there is a limit in which you can find out everything about the ensemble without disturbing any of the particles in it.”

    The key is to follow the weak measurement with just the right strong measurement. In the case of the spinning atoms, after applying the weak magnet to spread the beam vertically as before, an experimenter should pass the beam through a strong magnet tipped sideways. The second magnet splits the atoms into two beams, one with spins pointing left and the other with spins pointing right. Suppose the atoms originally had their spins pointing very nearly to the left. Then the second magnet will send most of the atoms into the left-spinning beam, which will reveal nothing new.

    A few atoms, however, will end up in the right-spinning beam, and they will tell a richer tale. That's because the weak magnet doesn't completely separate the up and down components of the atoms' original wave function. The not-quite-separate waves then interfere with one another in a way that greatly amplifies the vertical deflection of the right-spinning beam to reveal the mixture of up and down. Thus, the weak vertical magnet produces a robust measurement without flattening the atoms' quantum state (although the second magnet does collapse it).

    It's the interference that makes the whole scheme work. And for a given initial state of the atoms, experimenters can make that interference blossom by carefully “postselecting” a final state. “Postselection is a trick to amplify the weak measurement,” Vaidman says. The key is to make the final state of the atoms nearly as different as possible from the initial state—just as in the spinning-atoms experiment, the initial almost-left-spinning state and final right-spinning state are nearly opposites. Even then, the deflection remains smaller than the width of the spread-out beam, so experimenters can't measure it by running a few particles through their rig. Instead, they must measure the average deflection of many particles in the feeble right-spinning beam.

    All this might seem like much ado about nothing if a weak measurement provided the same information as a traditional measurement. But a weak measurement reveals more. A strong measurement reveals only the ratio of up and down in the atoms' original state. The weak measurement reveals the mathematical relationship between the two components—for example, the “plus” or “minus” in the right or left states. It's as if an ordinary measurement traces the silhouette of the wave function or quantum state, whereas a weak measurement yields a color photo of it.

    Mind-boggling precision

    The basic idea applies to any quantum particles, Vaidman says. Experimenters need only preselect and postselect states that are sufficiently different and sandwich between them a measurement for which, curiously, either state would yield an uncertain result. For example, photons can be polarized so that the electric field in them corkscrews to the right or to the left as the particles zip along. So physicists can preselect photons in the “right plus left” state and postselect those in the “right minus left state.” And they can expose the beam to an interaction that, say, would tug right- and left-polarized photons in opposite directions.

    That's exactly what Onur Hosten, now at Stanford University in Palo Alto, California, and Paul Kwiat of the University of Illinois, Urbana-Champaign, did to observe a new bit of physics called the spin Hall effect for light. In it, light passing at an angle from air into glass shifts sideways in a direction that depends on whether the light is left- or right-polarized. Hosten and Kwiat used the amplifying effect of weak measurement to observe that atom's-width shift, as they reported in 2008 in Science (8 February 2008, p. 787).

    The advance highlighted the potential of weak measurements to produce exquisitely precise results. That might sound paradoxical, as by design the weak measurement reveals almost nothing about the state of each individual quantum particle passing through an apparatus. What can be measured precisely, however, is not the state of the particles but the strength of the coupling to the pointer, says Andrew Jordan, a physicist at the University of Rochester in New York state. For example, in the spinning-atoms experiment, researchers can measure the gradient of the magnetic field, which couples the atoms' spin to the beam's deflection.

    Exploiting that fact, Jordan and colleagues used weak measurement in an optical scheme to detect changes in the angle of a mirror as small as 400 femtoradians, as they reported in 2009 in Physical Review Letters. To grasp how precise that is, Jordan says, suppose you used a mirror to direct a laser beam from Earth to the moon. Then changing the angle of the mirror by 400 femtoradians would cause the laser spot on the moon's surface to move by the width of a human hair.

    Weak measurement may soon find everyday applications. Jordan's scheme to measure the deflection of a light beam can also measure light's frequency, which determines how much a prism will deflect a beam. His team can already measure frequency as precisely as the best commercial devices. “You can use an expensive spectrum analyzer or weak measurement,” Hosten says. “But one costs $30,000 and the other a few thousand.”

    A fresh take on quantum conundrums

    Weak measurements seem to resolve some of the apparent paradoxes of quantum theory. For example, it might seem obvious that a particle has a position even before its position is measured. But quantum mechanics forbids that commonsense notion. In 1992, Lucien Hardy of Durham University in the United Kingdom dreamed up a “thought experiment” to drive that point home.

    Imagine firing electrons one by one through an interferometer, a device that lets a particle in through a single entrance and then sends it down two diverging paths (see figure, below). Before the exit, the paths merge again and the quantum waves describing the electron recombine. If the paths have the right lengths, the waves will interfere so that the electron always exits through one of two “ports.” Imagine further that you have an identical setup for antielectrons, or positrons, right next to the first device.

    Finally, suppose one of the paths for the electrons overlaps with one for the positrons so that the particles can collide. The particles' interaction would muddle the interference of the wave in the electron's interferometer so that the electron would sometimes come out of the wrong, “dark” port. So would the positron. In fact, if the interferometers overlap, then quantum mechanics predicts that sometimes both particles will emerge from their dark ports.


    The setup for Hardy's paradoxical experiment, as described in the text.


    But that's crazy. To emerge from the dark ports, the electron and positron had to interact. But in that case, as particle and antiparticle, they should have annihilated each other and disappeared. Nevertheless, quantum mechanics predicts that when both particles come out the dark ports, a standard measurement would reveal with certainty that the electron passed through its overlapping path. The same is true for the positron. So quantum mechanics seems to demand that both particles go through their overlapping arms, even though that leads to their destruction.

    Standard quantum theory resolves this paradox in an iron-fisted way: It forbids “counterfactual” arguments about measurements that weren't actually made. Detecting the electron in its overlapping path collapses the quantum state describing the two particles so that the positron is not in its overlapping arm. By obliterating the original state, the measurement renders invalid any speculation about what would have happened had the experimenter also looked for the positron in its overlapping arm. If you didn't look to see if the positron was there, then you can't assume that it was—even if that's what a measurement surely would have shown. Thus, Hardy argued, quantum theory won't allow you to talk about a particle's position before it's measured.

    Or will it? Weak values offer another way around this problem, as Aharonov and colleagues explained in 2002. The trick is to post-select the events in which both particles come out the dark ports and make weak measurements of which paths the particles go down. Simultaneous weak measurements will then show that the probability of finding the electron in its overlapping path and the positron in the nonoverlapping path is 100%. Likewise, the probability of finding the electron in its nonoverlapping path and the positron in its overlapping path is 100%.

    Once gain, the mind strains. A total probability of 200% seems to suggest that there are two pairs of particles inside the apparatus when only one pair went in. Not to worry: Weak measurements also show that the probability of finding both particles in the nonoverlapping paths is −100%, reducing the total probability to 100% and the number of pairs back to one.

    That analysis resolves the paradox with no ban on counterfactual reasoning and what you can talk about—if you're willing to accept negative probabilities. “Weak values have this consistency that standard quantum measurements don't,” says Lundeen of Canada's National Research Council. “If you're comfortable with negative probabilities, then you're happy.”

    This might seem like a moot point, except that 2 years ago, Toronto's Steinberg and Lundeen performed the experiment. They used weak measurements on photons instead of electrons and positrons, mimicking the electron-positron annihilation with a phenomenon in which a crystal will absorb two photons that pass through it simultaneously, but not one photon at a time, as they reported in January 2009 in Physical Review Letters. Three months later, Nobuyuki Imoto of Osaka University in Japan and colleagues reported similar results in the New Journal of Physics. The results conform to predictions, negative probabilities and all.

    A new quantum reality?

    Not surprisingly, weak measurements have been controversial from the beginning, although not in the way one might expect. The very idea of a negative probability seems nonsensical, but Vaidman quickly points out that the weak measurements are not true probabilities. Rather, he says, the negative value indicates that the pointer used to make the weak measurement moves in the direction opposite to the direction experimenters would expect if a particle were present. In the end, negative probabilities aren't so hard to live with, other researchers say.

    Instead, the real debate focuses on the claim that, in a sense, weak measurements pull back the veil imposed by standard quantum theory and allow physicists to begin to say something about the exploits of individual particles. Vaidman and Aharonov assert that weak measurements are “elements of reality” that reveal the true states of individual particles. So, for example, in Hardy's paradox, the weird probabilities apply to each pair of particles going through the apparatus, and, to a certain extent, physicists can begin to talk about how a quantum particle gets from one end of it to the other—something that is generally forbidden by standard quantum theory.

    Not so, says Ruth Kastner, a philosopher of science at the University of Maryland, College Park. To make a weak measurement, physicists must study scads of identically prepared particles in an ensemble. So by definition, a weak measurement is a statistical average that has little to do with reality so construed. “These values do not apply to any particular particle,” Kastner says. In claiming they do, Vaidman and Aharonov “pushed something a little farther than it would go,” she says.

    Aharonov responds: “I think she's totally confused.” As weak measurements do not disturb a system's wave function, they necessarily characterize each particle in the preselected and postselected ensemble, he says. “You can't say it's not a real property of each of these,” he says. “Then there is no other way to explain what's going on.”

    Two-slit redux.

    Each photon goes through both slits and has no trajectory, yet weak measurements trace the photons' average trajectories (graph, right).


    In fact, Aharonov goes further. When developing the concept of postselection, he and Vaidman imagined the preselected state evolving forward in time and colliding with the postselected state evolving backward in time. Such backward-evolving waves are more than a trick for making calculations, Aharonov argues; the future really can affect the present. “I believe you have to think about [the backward-going wave] as a real thing,” Aharonov says.

    Again, Kastner objects. In an actual weak measurement, everything is calculated after postselection. “It's all in the past,” Kastner says, so there's no need for quantum waves coming from the future. However, Steinberg, among others, says Aharonov's proposition deserves consideration, as it suggests there's more information available than standard quantum theory allows with forward-evolving waves alone.

    Rewriting the textbooks

    Even as the philosophical debate continues, experimenters are using weak measurements to perform feats recently considered impossible. For example, Steinberg and colleagues have used weak measurement to put a new spin on the “two slit” experiment: the most famous thought experiment in quantum mechanics and a classic demonstration of so-called wave-particle duality.

    In the experiment, light shines through two parallel vertical slits in a thin plate and onto a distant screen (see figure, above). The waves emerging from the slits overlap on the screen to create bright stripes where the waves reinforce each other and dark stripes where they cancel each other in a bar-code-like pattern that is a hallmark of wavelike behavior.

    Bizarrely, that “interference pattern” appears even if the photons pass through the slits one by one. So each particle literally must go through both slits at once and interfere with itself. Only if the experimenter tries to determine which slit the photon went through—perhaps by alternately closing one slit and then the other—do the stripes disappear and the photons act like particles. Among other things, the experiment shows that one cannot know both exactly where the photon is (which slit it's going through) and what its momentum is (at what angle it emerges from the slit), making it impossible to define its path.

    However, Steinberg and colleagues found a way to measure the average trajectories of many photons going through the two slits. To do that, they used a weak-measurement scheme that slightly altered the polarization of the photons depending on the angle at which they emerged from the slit. The polarization, in turn, allowed the scientists to determine the average momentum of the photons hitting each point on the screen. That was enough information for the researchers to reconstruct the average trajectories as they moved the screen farther from the slits.

    The experiment, reported recently in Science (3 June, p. 1170), doesn't violate quantum mechanics, Steinberg says; each individual photon still goes through both slits. But it eases slightly the prohibition against talking about particle trajectories. “The textbook explanation has always been, if you don't ask [experimentally] about the photon's position in the apparatus, then you shouldn't even discuss it,” he says. “I think some people are starting to reconsider that.”

    Similarly, in June, Lundeen and colleagues reported in Nature that they had used weak measurement to measure directly the wave function of photons emerging from an optical fiber. That's something that generations of physicists have learned cannot be done, as standard measurements reveal only the size or “amplitude” of the wave function and not its full mathematical complexity. “People have these hand-waving ideas of what you can and can't do,” Lundeen says, “and I'm kind of surprised that they haven't been taken to task earlier for some of them.”

    Such results must gratify Aharonov and Vaidman, the pioneers of the field. “It looks like time has shown that we were right and that [weak measurement] is completely universal,” Vaidman says. The growing body of experimental work will force physicists to rethink what it means to make a measurement, as it is no longer the simple matter taught in textbooks. That may disturb some of us who learned quantum mechanics the old-fashioned way.

  6. Newsmaker Profile

    Wayne Clough Wants Smithsonian Science to Escape Its Shadow

    1. Jeffrey Mervis

    Domestic politics compete with his billion-dollar plans for a global expansion of research to bolster the Smithsonian Institution's famed museums and collections.

    An impressive record as a researcher, university president, and fundraiser made G. Wayne Clough an obvious choice to become the 12th secretary of the venerable Smithsonian Institution in June 2008. His reputation as a consensus builder and a genuinely nice guy was also seen as a plus after his predecessor, banker Lawrence Small, was forced to resign when his management and spending practices created a furor at the quasi-governmental agency and within the halls of Congress. “If you find anybody who doesn't like Wayne, there's something wrong with them,” says Charles Liotta, a former vice president of research under Clough (pronounced “cluff ”) at the Georgia Institute of Technology in Atlanta and chair of the search committee that recommended him for the presidency in 1994.

    Clough's winning ways—this fall Georgia Tech will dedicate a new student learning center that bears his name—are enhanced by a south Georgian accent and a trim white beard that could land him a movie role as captain of an ocean liner. But behind that genial appearance is a strong vision—and a thick skin. Three years into his tenure, the 69-year-old seismic engineer is waging an aggressive campaign to end what he calls the Smithsonian's “near invisibility” on Capitol Hill and throughout the scientific community.

    He says its reputation as the nation's “attic”—the 137 million objects in its far-flung collections at 19 museums are unparalleled—has overshadowed the work being done at its nine research facilities. To bolster that research, he is one-third of the way toward raising more than $1 billion in the Smithsonian's first-ever capital campaign. He's using a $10 million gift from the Bill and Melinda Gates Foundation to seed interdisciplinary research collaborations that he likens to start-up companies. And to spread the word, he's broadening the Smithsonian's already extensive outreach efforts by digitizing its collections and striking a deal with Comcast to quadruple the audience for its television programs.

    A new strategic plan groups the Smithsonian's activities into four grand challenges: Unlocking the Mysteries of the Universe, Sustaining a Biodiverse Planet, Understanding the American Experience, and Valuing World Cultures. He says the exercise prodded the institution's 6000 employees to rethink their priorities; it also arms him to defend a $1.2-billion-a-year budget (65% from the federal government) in what Clough anticipates will be tough times ahead.

    Clough has already hit some bumps in the road since coming to Washington. His most publicized battle followed his removal last fall of a 13-second video from an exhibit, titled Hide/Seek, exploring sexual identity in American portraiture. Although many in the art community accused him of kowtowing to conservative politicians, he defends the decision as necessary to avert a potentially serious fiscal backlash from Congress.


    Although Clough seems to have weathered that storm, he remains in the midst of a less visible but no less acrimonious fight with archaeologists over an exhibit, which just closed in Singapore, containing artifacts from the Belitung shipwreck off the coast of Indonesia that were commercially salvaged and exploited. Scientists say the exhibit, which the Smithsonian helped to design, violates ethical guidelines and international treaties aimed at halting treasure hunting. Clough says that the exhibit's plans to come to Washington in 2013 are under review in the wake of the controversy. But he chides the scientific community for placing academic purity above pragmatism.

    Clough visited Science on 14 July to discuss his plans for the Smithsonian, which marks its 165th anniversary this month. Here are highlights of that conversation. A longer version is available online.

    On science's low profile:

    W.C.:People referred to the Smithsonian as “the nation's attic,” so they thought of it as a dusty place not going anywhere, looking backwards as opposed to looking forward. That hurt us a great deal when I went up on the Hill and spoke to Congress about the possibilities for funding [research]. They tended to view us as a Washington-based institution that was a museum, … and sometimes that was a pejorative term. … Certainly, science is clearly one of the most dynamic pieces of the Smithsonian, but it wasn't visible. It extended to the science community itself. … And the Smithsonian itself didn't put its pieces together.

    On the grand challenges:

    W.C.:It was an amazing, natural process. … We started out with maybe 20 areas of potential focus, and we ended up with four that we call our grand challenges. … They give you a set of umbrellas under which the Smithsonian's work takes place. That's not to say that you won't have something taking place that's outside of that. But you have to think very hard about why you're doing that.

    We have enough collections, fundamentally, in size—we have 137 million objects and specimens—so, now, we only want to grow our specimens if they meet this test of fitting within the grand challenges. … We have a process now where our directors meet regularly to make those joint decisions as to what we will not do anymore. Some of those decisions may get a lot harder, if, in fact, our federal budget is cut severely. We've been fortunate not to fall victim to that yet.

    On the Belitung shipwreck exhibit:

    W.C.:I'm told there are, perhaps, up to 1000 shipwrecks in shallow waters in and around Indonesia and other countries that cannot afford to undergo a thorough salvage exercise. And so somehow you're going to have to find a way to protect these shipwrecks, because otherwise, while you're standing there talking about the most pristine way to do it, somebody's going to come in and loot it.

    So I think the people in these professions need to sit down together and say, ‘What can we do about this?’ Because, as this shipwreck was discovered, it was in shallow waters, and, I was told, it could have been looted any day. So the Indonesians contracted with a company who did, at some point, get serious about curating the objects from it, and, therefore, there was some science base to the curation. … It explained a great deal about the trade between the Chinese and the Arab nations, which was very little understood.

    As it stands now, that exhibition will not come to the United States, and people who otherwise would have learned a great deal about this trade will not. … I think the curator, Julian Raby, and his staff felt, when they were working with the Singaporean government, which had, in fact, bought these artifacts for the express purpose of helping educate people, that they were doing something that was useful and productive. Now, certainly not everybody agreed with that, but that's the way these things are. … I think the Smithsonian tried to do it right.

    On removing a portion of the Hide/Seek exhibit:

    W.C.:I thought [the exhibit] was fantastic. It was based on scholarship; it was based on a careful choice of the objects, by and large. We had a review process. It turned out that particular video was not part of the review process, but that's another story.

    After the exhibition had been up for a while, a group obviously chose that [video] as a point of contention and exploited it, and it came in at a time when there was an election cycle, and so there was a lot of controversy in that sector. So I felt we ran the risk of losing the entire exhibition. The Smithsonian has been forced in the past to take exhibitions down … by Congress and by the public. Folks tend to forget we're funded 65% by the federal government, which means every person in America owns the Smithsonian, and part of our job is to be bridge builders, not divide builders. … Our objective is to engage as many people as possible in what we do, not simply show an object for its shock value. …

    I also had to step back and think, I'm in charge of the fate of 6000 people at the Smithsonian, and we have lots of ideas and plans going forward. We were clearly going to be going into a period of very difficult budget circumstances. And so, from that point of view, I didn't think we needed to be in a longstanding debate about religious desecration. And so to keep the exhibition up, I decided to remove the video. I think I made the right decision.

    On the road.

    Wayne Clough enjoys traveling to places where Smithsonian scientists are doing research, including (clockwise from top) the Antarctic, Wyoming, and Kenya.


    On accepting a donation from philanthropist David Koch, who supports efforts to cast doubt on climate change, to fund a $15 million Hall of Human Origins:

    W.C.:We don't take into account a person's political view. We would take a gift from George Soros, and we would take a gift from the Kochs, if they meet the criteria of philanthropists; that is, they make a gift without the intention of dictating content of what the gift is used for. Mr. Koch was, in fact, a perfect donor. He gave us his money. He never, at any time, interfered with the exhibition or the content of the exhibition.

    On its upcoming fundraising campaign:

    W.C.:The Smithsonian has never had a campaign before. It's always raised money, but it's done it sort of [on] a museum-by-museum basis and not in the sort of coherent, professional way that universities do it. And so we are gearing up to do something like that. … [Our] donor base is very generous, but it's small. We don't have an alumni base, and so we need to do everything we can to increase our donor bank. … At the end of the campaign, we hope to have raised a certain amount of money—well over $1 billion—but, particularly, we hope to have increased, for the long haul, people who are willing to give to the Smithsonian.

    On federal support for large scientific facilities:

    W.C.:You know, sadly, the federal government probably is out of the game [for the James Webb Space Telescope], and that's a loss, I think, for our country. Astronomy and astrophysics has been one of the great strengths of this country, and for our country to sort of withdraw from that, I think, is a mistake, and we see this happening in a number of places in our national endeavors now. We don't seem to be able to build big infrastructure projects anymore. We're not supporting the National Science Foundation like I think we should be. Some of the big international collaborative science initiatives are going elsewhere or are being initiated elsewhere and not here. China, particularly, is investing enormously in their science infrastructure. We're not. So I think there are a lot of signs that suggest that we have problems.

    On the Gates collaborations:

    W.C.:They're sort of like start-up companies, and not all of them will succeed. But that's okay because you have a lot of fun doing them, and people get to know each other. What we're doing is really a culture change at the Smithsonian. They're talking to each other and collaborating with each other, and so even if that particular idea does not pan out in the long run, it's not a failure. … Out of that set of 20, maybe only five will be able to sustain themselves for 10 years.