Oil executive: Harold Hamm is tipped to head the US Department of Energy. (Courtesy: CC BY-3.0/ David Shankbone)
US scientists have responded to the choice of Republican Donald Trump as president-elect with a mixture of astonishment and anxiety. Having anticipated the election of Democrat Hillary Clinton, who was backed by a team supportive of science, researchers now fear a future in which science policy may play a minor role in public affairs.
The most difficult issue for scientists is gauging the position the Trump administration will take on science. “He didn’t say much, if anything, about science during the campaign,” says physicist Neal Lane, a former presidential science adviser who is now a senior fellow at Rice University’s James A Baker III Institute for Public Policy. “Trump has said so many different things, many of them contradictory, that it is not at all clear what he will do.”
That view is shared by physicist Michael Lubell from City College of New York, who is also public-affairs director at the American Physical Society. “We’re looking at a black hole,” he says. “Nobody knows what this guy is going to do – and I’m not sure he does.”
The community’s angst reflects the severity of the scientific issues that Trump faces once he is inaugurated on 20 January. “[He] will confront a broad range of global challenges from addressing climate change and securing our energy future to sustaining investments in scientific research efforts in numerous areas, including medicine,” notes a statement from the American Association for the Advancement of Science (AAAS). Rush Holt, a physicist and former Democratic congressman who is AAAS chief executive, adds that Trump “must be prepared to advance science, technology and education to drive economic progress, innovation and jobs, and to improve people’s lives”.
Little contact
Uncertainty about the incoming administration’s ability to meet those challenges extends to the identity of key members of the Trump campaign. “We tried to make contact with his campaign people on science,” says Lubell. “The only name that surfaced was from a small college in Iowa with a background in economics – and we got no response from him.”
Adding to the scientific community’s concern is that Republicans, some of whom take a sceptical view of certain aspects of science, will control both the Senate and the House of Representatives. “I expect that Trump will defer to the Republican-controlled Congress on priorities for science, which would not bode well for some fields,” says Lane, adding that “even peer review has been attacked” by some House members.
Nobody knows what this guy is going to do – and I’m not sure he does
Michael Lubell, City College of New York
Congress holds the power of the purse and many Republican members want to reduce the national budget deficit by cutting back on spending. President-elect Trump has stated his desire to reduce taxes, increase spending on defence and infrastructure as well as maintain current spending levels on social initiatives. This would leave little cash for discretionary programmes, including support for scientific research. “Many of the things Trump has said he planned to do are very costly,” says Lane. “Conservatives in Congress are not likely to want to raise money through taxation; they’re more likely to reduce revenues. So nondiscretionary spending, including federal research budgets, might be expected to see continued cuts.”
Fox guarding the hen house
One area of science that is almost certain to suffer under the new administration and Congress is climate change. Donald Trump has described global warming as a hoax perpetrated by the Chinese government to harass the US, while many Republicans deny there is a human contribution to global warming. “I’m afraid that our worst fears have been realized,” says climatologist Michael Mann from Pennsylvania State University. “If Trump makes good on his campaign promises and pulls out of the Paris treaty, it is difficult to see a path forward to keeping warming below dangerous levels – it might make it impossible to stabilize planetary warming below an increase of 2 °C.”
The stewardship of science-based government agencies will, of course, depend on the individuals nominated to head them. Again, the Trump campaign has revealed little information, but a few clues have emerged. Harold Hamm, an oil-industry executive from Oklahoma, has emerged as a possible head of the Department of Energy. This appointment, if it happens, would be in contrast to the approach of president Barack Obama who selected senior academics, such as the Nobel laureate Steven Chu, to that position. Indeed, climate-change sceptic Myron Ebell of the Competitive Enterprise Institute, currently heads the Trump transition team for the Environmental Protection Agency – in what Mann describes as “a case of the fox guarding the hen house.”
The most important appointment for the scientific community is that of presidential science adviser, who traditionally heads the Office of Science and Technology Policy (OSTP). “The nation’s incoming president will need to move quickly to appoint a respected scientist or engineer to serve as the next science adviser, to ensure immediate input related to science and technology,” says Holt. “The next science adviser will need to be integrated at the earliest possible stage into the administration’s decision-making process – not just on topics with an obvious science connection such as infectious disease response, but on matters concerning diplomacy, cyber security, agriculture and advanced manufacturing, as well as resilient infrastructure, which also relate to science and technology.”
However, Lubell wonders whether Trump will even appoint one. “He’ll face a problem finding a science adviser, if he wants one,” he says. “No law says the position must be filled and if Trump says ‘we don’t need the OSTP’, Congress won’t fund it.”
Pro-science senators
Yet amid the gloom, analysts still see a glimmer of hope for science. “There are pro-science Republicans and Democrats in the Senate, even some in the House,” adds Lane. While Lubell points to Trump’s campaign catchphrase: Make America Great Again. “The slogan provides an opportunity for him to say we need to claim American leadership in science,” he says. Mann expresses hope that “the world will find a way to move forward in combating climate change even if the US refuses to play an active role”.
US science now enters a new phase and officials say that they must make a case for research to the new administration and the general public. “The community, and especially corporate leaders who are the beneficiaries of the federal support of research in universities and national labs and centres, need to work even harder to get the story out to the public and the elected representatives, whatever their party and whatever their office,” says Lane.
Simple but complex: a Pavoni Europiccola coffee-maker raises all sorts of physics questions. (Courtesy: Robert P Crease)
Peter Stephens pours water into the pressure vessel of my espresso maker, screws on the top, and presses a switch. An experimental physicist at Stony Brook University, he’s dropped by my office to drink coffee and discuss physics. He knows my device well. It was once his; he gave it to me after being appointed associate dean and moving to a larger office with its own coffee maker as a literal perk.
At first glance the Europiccola device – made in Italy by the long-standing Milanese firm La Pavoni – looks like it belongs in a museum of 19th-century physics equipment. About 25 cm big and made of brass, its main feature is a pressure vessel sprouting gauges, tubes, knobs and a manual lever over a bell-shaped attachment. The only hint it’s a 20th-century device is a 110 V electrical cord trailing from the base.
After a minute, the device begins to groan and make soft pops like it’s muttering to itself. When a thin ribbon of steam curls above the safety valve, Stephens announces: “We’re almost ready!” To be sure, he twists the knob on the steamer, which responds by issuing a confident jet. He pumps the lever, pushing a shot of coffee into our cups. An invigorating aroma wafts into the corridor.
“Cheers!” Stephens says as we drink up.
Functioning antique
Coffee is often the fuel of choice for physicists wishing to stay alert to solve a thorny theory or eke out a crucial experimental finding. But most rely on coffee from a pot or vending machine, and it’s a shame not everyone can have a once-popular Pavoni. Mine gets us chatting about the physics of coffee-brewing.
The Pavoni’s main parts are a pressure vessel to heat water, a lever-driven piston and a filter basket. As the water heats, some turns to steam, which drives hot water into the piston chamber mounted on the pressure vessel. Raising the lever pulls up the piston, opening a valve that lets water flow into the chamber. Pressing the lever down forces this water through coffee grounds in the filter basket into one or two cups waiting below.
Yet the Pavoni’s interesting physics, Stephens explains, has nothing to do with Boyle’s law or the bare mechanics of the water flow, but with other aspects of coffee-making. Take the temperature differential between the water in the pressure vessel and the water flowing through the coffee grains. The temperature of the former is about 120 °C, while the optimal temperature of the latter is 91–97 °C. Any cooler and the liquid absorbs the coffee poorly; any hotter and the water burns the grains and makes the coffee taste bitter. The piston cylinder, however, serves as a heat sink, making the water temperature drop.
There’s also interesting physics in how substances get extracted from the coffee grains into the liquid. Coffee beans are made of hundreds of different types of molecule that give the drink its flavour. Brewing an espresso – “quick” in Italian – involves passing water through ground roasted beans. The trick is to extract the tasty flavours and the caffeine, which tend to come out quickest, and leave behind the bitter compounds. It’s a problem that sends Stephens to the blackboard to draw flow diagrams.
Extraction depends on the grains’ size and shape, he explains, as well as the density of their packing, the water temperature and the liquid flow rate. The larger the grains, for instance, the smaller the surface-to-volume ratio, diminishing the percentage of substances absorbed. But if the grains are too fine they turn into a wet paste, slowing the flow.
The Pavoni leaves most such factors to the user: other machines, in contrast, use pods with pre-ground beans, gauges to control the water temperature, and springs or pumps to regulate the water flow. I’ve heard it dismissed as a “functioning antique” doomed to be retired to a user’s storage closet. I kind of get it: a coffee maker shouldn’t act like a finicky experimental facility. But I like that the user is in control of the process rather than it being a matter of inserting pods, adjusting settings and pushing buttons.
The critical point
My Pavoni is neither the simplest nor the most complex home espresso maker. A good account of their history is found in Ian Bersten’s book Coffee Floats, Tea Sinks: Through History and Technology to a Complete Understanding (1993 Helian). Mechanically simplest is the famous stovetop Moka. You pour water in the base, insert a basket with grounds in, screw on an upper chamber and put the whole pot on the stove. Steam drives the hot water up through the grains; it’s flow-up rather than drip-down. I bought my first at a flea market in Rome for about $1 as a grad student and have used it for decades.
Even in this simple device the physics is complicated, as Stephens and I discover (2008 Am. J. Phys.76 558). It hadn’t occurred to us, for instance, that the pressure in the bottom vessel would be anything other than the saturated vapour pressure of the heated water. But because some air is initially present, the rising temperature creates an “overpressure” through plain old PV = Nrt. “The more mechanically simple, the harder to analyse,” Stephens says.
Stephens has to return to the dean’s office before we get round to discussing how to froth milk or roasting and grinding beans. “These are the kinds of things that interest me about the natural sciences,” Stephens says as he leaves. “Exploring the interface between what is readily quantified – pressure, temperature and volume – and complex intangibles like the flavour of a cup of coffee.” I won’t look at a cup of coffee in the same way again.
Feeling full: one way to deliver satiety might be to add functional ingredients to emulsions such as salad dressing, which is made of droplets of oil suspended in water. (Courtesy: Shutterstock/hjochen)
The developed world is getting fatter. In the UK, the incidence of obesity has almost quadrupled in the last 25 years; within the (mostly wealthy) countries that make up the Organisation for Economic Co-operation and Development (OECD), the majority of the population is now either overweight or obese. The reasons for this collective weight gain are manifold, and although sedentary lifestyles and the ready availability of calorie-dense foodstuffs are obvious contributors, they don’t appear to be the whole story. When we eat, our bodies respond with an incredibly complex hormonal process, one that takes into account not just what’s on our plates that day, but also what we have eaten in the past, and how much of it. Unfortunately, the outcome of this response is that, essentially, we train our bodies to get fat – and it doesn’t seem to be easy to train them to become thin again.
As an example, consider the process we use to recognize when we have eaten enough. The sensations of satiety (recognizing that we are full) and satiation (recognizing that we don’t want to eat again yet) stem from external social cues (such as plate size and portion size) and mechanical cues (a full stomach), but also from the response of our metabolism. When our gut detects the presence of fatty acids, sugars, amino acids or the breakdown products of proteins, it releases several known “satiety” hormones. These hormones help make us feel “full”, but the way our body releases them and how our brain reacts to them is complex and not yet fully understood. Our gastrointestinal tract is a complex organ: for example, the taste receptors in our mouths – the ones that enable us to tell whether foods are sweet, salty, sour, bitter and savoury (umami) – are also present in our stomach, small intestine and colon. It is not just our mouths that “taste” our food.
Injecting any of the satiety hormones temporarily decreases calorie intake in both lean and overweight humans, but unfortunately, these hormones are rapidly turned over in the body and the effect does not last to a second meal. Moreover, repeated doses do not lead to weight loss because our complex interconnected hormonal response adjusts to the presence of additional hormones. Thus the satiety hormones themselves probably do not represent good candidates for therapeutics. So what are the alternative prospects for intervention?
One option is to use social cues to promote satiety by, for example, decreasing the portion sizes of packaged foods: unsurprisingly, we eat less when less is available. We could also make foodstuffs denser and chewier, since we eat less when we eat slowly and chew more. However, given our fast-paced lifestyle and the prevalence of food-on-the-go, this may not be a realistic choice. And while we’re being pragmatic, we should also recognize that processed foods aren’t going to disappear overnight.
An alternative option is to re-engineer our food. That may sound extreme, but in some sense, it has already been done: many modern processed foods have been developed in response to consumer desires for creamier, richer, tastier foods. The challenge this time is to create tasty foods that can also deliver triggers for the release of satiety hormones directly to those tissues where they will do most good. This is where soft-matter physics enters, with the development of so-called “functional” foods.
Beyond mere nutrition
Functional foods are foods that offer added physiological effects beyond “normal” nutritional value and taste. Examples include bread, milk and orange juice enriched with vitamins; yoghurt with added “probiotic” bacteria; eggs with increased omega-3 fatty acids; and meat products with added fibrous material to decrease fat content. Functional foods can also make life easier for people with allergies and other health conditions: lactose-free and gluten-free foods are increasingly seen on supermarket shelves. But replacing ingredients in foods with healthier alternatives – or, in the case of satiety-promoting ingredients, adding new ingredients to established recipes – is not always easy. Food formulations are complicated and have often been developed empirically over time, so that removing an ingredient or adding a new one can have unexpected outcomes.
The task of understanding the structures of foodstuffs and food formulations falls squarely within the realm of soft-matter physics: the study of complex fluids containing dispersed structures such as bubbles, colloids, emulsions and/or polymers. The size of these structures ranges from nanometres to microns, similar to the length scale that you can detect on your tongue or in your mouth as you chew. Ice cream, for example, contains air bubbles, emulsions, ice crystals as colloidal particles, and proteins as both polymer and amphiphile (a molecule that has both water-soluble and water-insoluble parts). Chocolate consists of cocoa particles, sugar crystals and protein polymers in a continuous phase of cocoa butter. Beer foam is stabilized by polymeric biomolecular degradation products. And to a soft-matter physicist, pasta is basically just an amorphous carbohydrate in a glassy phase. All of these food formulations are beleaguered with biological complexity, but they are tractable and offer many approaches for delivering new, functional ingredients to the correct part of the body.
One possible approach for delivering satiety-promoting hormones to the gut would be to use emulsions – droplets of one liquid (the “dispersed phase”) suspended in another (the “continuous phase”). Many different processed foods contain emulsions: salad dressings, for example, are oil droplets suspended in a water-rich phase, while butter and margarine are water droplets suspended in an oil-rich phase. The emulsion droplets can be stabilized by amphiphiles (emulsifiers) to prevent coalescence, or they can be suspended in “texture modifiers” that thicken or gel the continuous phase, preventing droplets colliding. As these systems consist of aqueous, oily and amphiphilic phases, they can also accommodate many different functional ingredients to promote satiety, potentially simultaneously. By combining and processing emulsions appropriately it is possible to create a range of textures, from pastes and gels to freely flowing liquids. Some can even be dried and added as a powdered ingredient. Importantly, emulsions can be created from a range of food-grade ingredients using relatively simple and energy-efficient processing methods. Emulsions do have some limitations, however, many of which are encountered during food preparation. High and low temperatures (such as those encountered when cooking, chilling or freezing food), vigorous mixing, and changes in pH can all cause the droplets in emulsions to become unstable. This creates problems for would-be developers of functional foods. If oil-in-water emulsions are destabilized, for example, an oil-rich phase can be formed in or on the foodstuff – an undesirable product behaviour known as “oiling out”. The stability of the emulsion droplets can be improved by coating them with a thin solid surface layer built up from charged polyelectrolytes such as carbohydrate polymers or proteins. This layer can be chosen so as to dissolve or become porous only under certain conditions of pH and/or salt, for targeted release of satiety factors at certain places in the gut.
The surface layer does not have to be thin and does not have to be formed from polymer layers: cellulose particles or even smaller emulsion droplets that are themselves stabilized with a surface layer of protein can pack around an emulsion droplet, forming what is known as a Pickering emulsion (figure 1). The use of such emulsions, however, depends on the food: emulsions of this size can be detected in the mouth, and in semi-liquid preparations such as yoghurt, they give an unpleasant gritty consistency.
1 Protect and release Emulsion droplets are often stabilized by small-molecule emulsifiers, but they can also be stabilized by small particles (top) or by biopolymers such as proteins or polysaccharides (bottom). When the droplets are coated in smaller particles, they are known as “Pickering” emulsions. Both particles and polymers create a solid shell around the emulsion, protecting ingredients inside the droplet from environmental degradation. By carefully selecting the shell material, these emulsions can also be designed to release their content only in certain places in the gastrointestinal tract, delivering functional ingredients such as satiety factors to the location where they have the most impact.
A further example of emulsion technology is an emulsion droplet captured within an emulsion – a hierarchical structure known as a “multiple emulsion”. Examples might be oil droplets within a water droplet suspended in an oil continuous phase, or water droplets inside an oil droplet in a primarily aqueous formulation. Multiple emulsions are useful for “trapping” volatile ingredients, preventing them from diffusing out of the food by surrounding them with a medium through which they cannot pass. They are also useful for trapping ingredients that might otherwise taste bitter, by preventing their release in the mouth. Finally, multiple emulsions can protect fragile ingredients from the surrounding environment, preventing unwanted chemical reactions that may lead to food spoilage.
Although emulsions offer many opportunities for encapsulating and delivering functional ingredients, unfortunately the development of functional foods is a little more complicated than simply picking the right emulsion off the shelf. Our body responds differently to emulsion particles of different sizes and compositions. Some studies have shown that smaller emulsion droplets deliver both calories and satiety, while larger ones deliver the calories but with a muted satiating effect. The location where the emulsion is processed within the body also matters: if oily emulsions are unstable in the acidic environment of the stomach, the stomach becomes lined with fat, which seems to decrease satiety. But the breakdown products of fats are satiety-inducing factors themselves. Until we understand this complex interplay between the processing conditions that make emulsions larger or smaller, our enjoyment of the resulting foods in terms of taste and texture, their digestion in our gut, and the subsequent release of satiety hormones, we are trying to hit a moving target.
Protein power
Proteins are also attractive ingredients for food structuring. Compared to fats, they have two important advantages: a lower calorie density and an increased intrinsic satiety. Simple changes in temperature or pH can cause proteins to form filamentous (transparent) or particulate (opaque) gels that can be used to give foods texture. As mentioned above, these texture-modifying gels can be used to prevent or slow the emulsion droplets coalescing, by thickening the surrounding medium. Alternatively, by controlling how proteins stick together through simple changes in temperature and/or pH it is possible to form protein particles that act similarly to emulsions. Like emulsions, these can be used to encapsulate and promote the slow release of satiety-promoting ingredients, while also giving foods a “creamy” texture without the addition of fats or oils.
Similar effects can be achieved with carbohydrate polymers such as starch, cellulose, chitosan, alginate and gums including guar gum and xanthan. Many of these are used to encapsulate bacteria as probiotics; however, careful processing is required to make these capsules resistant to the acid environment of the stomach, which could otherwise destroy the bacteria before they reach the intestine. Many of these polysaccharides are also used as thickening agents, and a number of them cannot be digested, so do not directly contribute to calorie content. Some of these “dietary fibres” are also intrinsically satiety-inducing, perhaps by adding bulk or increasing water content to foods and giving rise to a mechanical feeling of fullness, but possibly by triggering the release of satiety hormones following fermentation in the intestine.
Foods for the future
Re-engineering processed foods to have a lower energy density is, in theory, a relatively straightforward matter: all you need to do is replace high-calorie ingredients (such as fats) with low-energy-density alternatives (such as dietary fibre). However, doing so typically has an impact on consumer satisfaction, as both the taste and texture of the food are affected. Food physics offers the opportunity to get around this dilemma by creating new products that mimic the texture and taste of unhealthy but well-loved foods, with added components that, when released in a controlled fashion at specific sites within the body, improve our feeling of satisfaction. Clever food processing also offers the potential for decreasing the amount of salt and sugar in processed foods, at least where they are added for reasons other than taste or nutrition.
In an ideal world in which processed foods were eaten rarely or not at all, such solutions would not be necessary. However, in a world where 90% of Americans purchase convenience foods and more than 50% of the calorie intake in the UK comes from ultra-processed and energy-dense foods, such advances are clearly desirable. Perhaps clever physics may yet help us stem the developed world’s obesity crisis.
Fresh evidence for a new state of matter called a supersolid has been put forth by two independent teams of physicists. Supersolidity has been a controversial concept whereby some atoms in a solid material are able to form a superfluid at very low temperatures – allowing them to flow ghost-like through the solid without any resistance. While initial observations of supersolidity in solid helium-4 in the 2000s have since been explained in terms of more mundane physics, some physicists believe that supersolids should exist – at least in principle. Now, Wolfgang Ketterle and colleagues at the Massachusetts Institute of Technology in the US and Tilman Esslinger and colleagues of ETH Zürich in Switzerland have created supersolid analogues using ultracold atoms. Both systems comprise Bose–Einstein condensates (BEC), which are already superfluids. The teams used different optical techniques to make the atoms arrange themselves into crystalline structures of high and low density resembling a solid. They then showed that the atoms can flow freely through such crystals, while the regions of high and low density do not move. While these experiments involve dilute gases, rather than actual solids, both studies show that the supersolid state of matter is possible. Both experiments are described in preprints on arXiv.
Perimeter Institute and South American Institute for Fundamental Research launch partnership
Early career: partners meet at the Advancement of Science in South America symposium in Brazil. (Courtesy: Perimeter Institute)
The Perimeter Institute in Canada and the South American Institute for Fundamental Research (SAIFR) based at the São Paulo State University (UNESP) in Brazil, have come together to support exceptional early career physicists. The partnership was launched yesterday in a special ceremony held during the Advancement of Science in South America symposium in Brazil. “Brilliant young people are the lifeblood of this basic field of scientific research, where one breakthrough can literally change the world,” says Perimeter director Neil Turok. “The values that drive Perimeter’s success – the pursuit of ambitious research goals and the promotion of access to excellence for all – align closely with those of SAIFR at UNESP. We see this as an exceptional opportunity to work together and catalyse rising talent throughout South America, while increasing scientific interaction between Canada and the continent.” The partnership programme will develop training programmes for emerging talent at the graduate and postdoctoral levels in South America and provide opportunities for talented students to attend the Perimeter Scholars International (PSI) graduate programme in Canada. It also aims to improve educational outreach in middle and secondary schools in South America and train teachers in the use of Perimeter Institute in-class resources throughout school systems. The partnership will also set up joint scientific conferences between the two institutes, as well as having a shared faculty member – Pedro Vieira – who will divide his time between both institutes.
Photoionization measurement breaks the zeptosecond limit
Electron snapshot: the probable position of the remaining helium electron after photoionization. (Courtesy: M Ossiander/TUM, M Schultze/MPQ)
The laser-induced ejection of electrons from an atom has been measured at a time resolution of several-hundred zeptoseconds. Reinhard Kienberger and colleagues at the Max Planck Institute of Quantum Optics, the Technical University of Munich and Ludwig Maximilians University, all in Germany, fired a 1 as (10–18 s) extreme ultraviolet light pulse at helium atoms, which ejects electrons in a process called photoionization. This is done in the presence of a much longer 4 fs (4 × 10–15 s) infrared laser pulse, which has the effect of accelerating the ejected electron. The kinetic energy of the electron is detected and is a function of the time difference between the peak amplitudes of the two pulses. This time difference can then be used to study the dynamics of how the electron is ejected from the helium atom. This process can take between 5–15 as and Kienberger and colleagues were able to study it at a record-breaking precision of 850 zeptoseconds (850 × 10–21 s). Helium is a relatively simple system, so the measurements should allow physicists to compare theoretical models of photoionization with experimental results. The research is described in Nature.
Republican-candidate Donald Trump’s surprising US presidential victory this morning presents a significant conundrum to the American scientific community. The community has largely supported the Democratic agenda of Hillary Clinton, who declared: “I believe in science.” Trump, in contrast, has called climate change a hoax devised by the Chinese to embarrass the US, has threatened to depart from the Paris agreement on climate change, and has promised to cut back on government regulations that encourage renewable-energy technologies. He has also pledged to bring back the coal industry.
Despite those comments, president-elect Trump’s campaign paid little attention to scientific issues. He did talk of a “commitment to invest in science, engineering, healthcare, and other areas that will make the lives of Americans better, safer, and more prosperous”. He also called for programmes, “such as a viable space effort and institutional research, that serve as incubators to innovation as well as for the advancement of science and engineering in a number of fields”. However, the campaign laid out few concrete examples of a science policy and did not release a list of individuals responsible for science policy.
Checks and balances
The presidency is, though, just one facet of US governance, which incorporates “checks and balances” on executive powers. The American constitution requires the House of Representatives to authorize federal spending, while the Senate must agree to that spending and approve major government appointments, such as the president’s cabinet members and judges.
For the past six years, president Barack Obama has had to deal with Republican majorities in both House and Senate. That American version of cohabitation significantly reduced his ability to carry out his agenda; it also created political deadlock that briefly closed down government operations and reduced the pace of legislation to a crawl.
Republican control
When he takes office in January, however, president Trump will have the advantage that the Republicans control both houses of the legislature. Since a large majority of Republicans in office have denied the connection between human activity and climate change, American participation in efforts to reduce global warming appears doomed. The party’s manifesto also calls for significant cutbacks in support for the Environmental Protection Agency.
That could slash its regulations on fossil fuels and overturn its emphasis on renewable-energy sources. The Obama administration’s proposed financial-year (FY) 2017 budget for the Department of Energy’s programmes on energy efficiency and renewable energy increased by 40% over the FY 2016 figure. That increase now seems moot. On the other hand, Trump has expressed his interest in supporting space travel, which looks positive for NASA’s budget.
Republican domination of government promises other areas of impact. Lamar Smith, the Texas Republican who heads the House Committee on Science, Space and Technology, has frequently taken the National Science Foundation (NSF) to task for its support of sociological science projects. The agency could lose funding for such research, although its support of hard science should survive.
Lost allies
The scientific enterprise may also suffer from the loss of two long-serving Senate Democrats who did not run for re-election: Maryland’s Barbara Mikulski, who has been a strong backer of NASA and other scientific agencies, and Barbara Boxer of California, a powerful supporter of environmental efforts. Even though they were in the minority in government, they had strong influence on decisions. Their successors are both Democrats, but they will lack the power that Mikulski and Boxer had obtained through their political longevity.
President-elect Trump will not necessarily have an easy ride with Congress. Throughout the election campaign he disagreed with several Republican congressional leaders, most notably House of Representatives speaker Paul Ryan. Those disagreements focused on immigration, global trade and the treatment of minorities. But arguments over priorities could wash over into scientific areas.
The transition to president Trump comes at a time when the government-sponsored spending on R&D as a share of the overall R&D funding has fallen. Estimates from the NSF’s Center for Science and Engineering Statistics indicate that business spending represented 69% of the $499bn that the country spent in FY 2015, while the government’s share was 23%, a record low. However, analysts see some indication that the government percentage might have increases in FY 2016, which ended on 30 September.
Advice for the president
As for how president Trump should deal with scientific issues, a report by Rice University’s Baker Institute for Public Policy – headed by the physicist and former presidential science-adviser Neal Lane – recommends a series of actions related to the Office of Science and Technology Policy (OSTP) that the science adviser heads.
The report calls on the president to choose – soon – a nationally respected scientist or engineer as science adviser and to nominate him or her to head OSTP; to direct the presidential personnel office to seek the science-adviser’s advice on filling senior positions in government agencies related to science and technology; and to consult with the science adviser “to quickly appoint a diverse membership” for the President’s Council of Advisors for Science and Technology, and regularly meet with that group.
Whether Donald Trump will take that advice remains to be seen.
A group of scientists in Europe has discovered a new kind of magnetic structure in which nearby atomic spins form a spiral. The results confirm a nine-year-old theoretical prediction of so-called “spiral spin liquids” and also reveal the existence of an unexpected vortex state that could potentially be exploited in ultra-high-density magnetic-storage devices.
In ferromagnets such as iron, the magnetic moments, or “spins”, of the material line up with one another over large distances – because this alignment lowers the energy within the material. In what are known as “frustrated” magnets, in contrast, atomic spins are positioned such that multiple different arrangements of spins can place the system in its lowest energy (ground) state. Spins therefore continually reorient themselves as the system flips from one ground state to another.
“Spin liquids” are frequently found in frustrated magnets, and have intermediate order. The material itself is crystalline, meaning that its constituent atoms sit at well-defined points on a lattice. However, the orientation of those atoms’ spins fluctuates continually, just as the position of atoms and molecules within a liquid changes from one moment to the next. But like the correlations that exist between nearby molecules in water, so neighbouring spins in this type of material also fluctuate collectively.
Angular offset
Although physicists have been observing spin liquids for years, spiral spin liquids have remained unconfirmed experimentally until now. Predicted by Leon Balents of the University of California in Santa Barbara and colleagues in 2007, they require nearby spins to be correlated such that the orientation of an atom’s spin axis is offset from that of its nearest neighbour by a certain angle. The size of that angle fluctuates continually in time, as well as in space.
Oksana Zaharko of the Paul Scherrer Institute (PSI) in Switzerland and colleagues set out to observe a spiral spin liquid in the material manganese scandium thiospinel (MnSc2S4), which is made up of antiferromagnetic manganese ions held in a frustrated structure by ions of scandium and sulphur. The researchers’ challenge was to make a sample that was large and pure enough so that it unambiguously generated the signature of a spiral spin liquid. This is a “spiral surface” in the diffraction pattern created when the material is bombarded with neutrons at low temperature.
To do this they used a slow and painstaking process to grow single crystals of MnSc2S4 and then combined multiple crystals to obtain a measurable signal. Having taken over a year to amass some 30 mg in total, they placed their sample in the Diffuse Scattering Neutron Time-of-Flight Spectrometer (DNS) at the Jülich Centre for Neutron Science in Germany. Then, as they cooled the sample down to just a few degrees kelvin, they found what they were looking for: clear evidence for the spiral surface in the sample’s diffraction pattern.
Unambiguous proof
According to Zaharko this is the first “unambiguous” proof of a spiral spin liquid. She points out that a group led by team-member Alois Loidl of the University of Augsburg had found evidence for the spiral in powdered MnSc2S4 using neutron diffraction as far back as 2005, but says that Loidl’s group found “just a good hint” rather than a clear signal.
However, while the latest data confirm the existence of spiral spin liquids, they do not support a second prediction made by Balents and colleagues nearly a decade ago. This is the somewhat counter-intuitive notion of “order by disorder”, in which a spin liquid collapses to a unique ground state selected by thermal fluctuations. Instead, the team found that the MnSc2S4 became ordered as it was cooled below 2.3 K, which, says Zaharko, was caused by atomic spins coupling with their third nearest neighbours, as well as their nearest and second nearest neighbours.
Balents says he is “very pleased” that his group’s prediction of spiral spin liquids has finally been confirmed by what he describes as a “beautiful” experimental study. He is not concerned about the absence of proof for order by disorder, explaining that “many other perturbations can perform the ground-state selection at lower temperatures” and noting that evidence for this mechanism has in any case been found in a number of other frustrated magnets.
Denser memories
He adds that Zaharko and colleagues have found “exciting” evidence that the spins in MnSc2S4 create a vortex shape when exposed to a magnetic field, something that he and his colleagues did not anticipate in their model. Zaharko says that this finding might in future yield higher-density disk drives, given that vortices measure only about 5 nm across, much smaller than features in today’s leading drives. But she cautions that practical devices will require “huge work in materials science” to increase operating temperatures.
Masaki Hori at the Max Planck Institute for Quantum Optics in Garching, Germany, and members of the CERN-based ASACUSA collaboration have made the most precise measurement ever of the antiproton/electron mass ratio. This was done by studying antiprotonic helium, which is an exotic atom comprising an antiproton, an electron and a helium nucleus. The team cooled about two-billion antiprotonic helium atoms to about 1.6 K. Then it measured the energies of 13 different atomic transitions using laser spectroscopy. The experiments revealed that the antiproton/electron mass ratio was identical to the proton/electron mass ratio to better than one part in one billion. If nature obeys charge, parity and time-reversal (CPT) symmetry, then these two mass ratios should be identical. Any discrepancy would therefore be of great interest to physicists because it could provide a glimpse of physics beyond the Standard Model of particle physics. The measurement is reported in Science.
Australian radio telescope kicks off alien search
The Parkes radio telescope in New South Wales, Australia, has begun its observation run as part of the Breakthrough Listen initiative – the $100m search for intelligent life beyond Earth, launched in 2015 by entrepreneur Yuri Milner and Stephen Hawking. Together with the Green Bank Telescope and the Automated Planet Finder at Lick Observatory in the US, and the newly built Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China, the observatories will spend the next decade studying exoplanets for any signs of developed life with technologies similar to our own. The Parkes telescope has access to the Southern Hemisphere sky, which the Breakthrough scientists deem as “rich with targets”, including the centre of our Milky Way galaxy, large swaths of the galactic plane, and other galaxies in the nearby universe. “The addition of Parkes is an important milestone,” says Milner. “These major instruments are the ears of planet Earth, and now they are listening for signs of other civilizations.” The Australian telescope’s first observation as part of the Breakthrough programme took place yesterday and it studied the newly discovered rocky exoplanet orbiting the nearest star to the Sun, Proxima Centauri.
Nanobionic spinach leaves could detect explosions
Spinach sensor: researchers embedded carbon nanotubes into spinach leaves. (Courtesy: M H Wong)
Plant leaves embedded with carbon nanotubes (CNTs) could be used to detect chemical explosives, thanks to new work done by researchers at the Massachusetts Institute of Technology in the US, who have transformed a plant into a living sensor that wirelessly relays this information to a handheld device like a smartphone. The technique for engineering electronics into plants, known as “nanobionics” is a new and upcoming field of research that could have a variety of applications – for example, it could be used in agriculture to improve crop yields and margins. The MIT team, led by Michael Strano, wrapped single-walled CNTs (that fluoresce in the near-infrared spectrum) in a polymer that is sensitive to molecules in certain explosives. If the molecules bind to the polymer, the fluorescence of the CNT changes and the signal can be picked up by an infrared camera to indicate the presence and the amount of explosive present. Read more about the research at nanotechweb.org.
You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on spotting spin-spirals in a quantum liquid.
Researchers at the Institut d’Optique Graduate School at the CNRS and Université Paris-Saclay in France have developed a new way to rearrange cold atoms one-by-one in fully ordered arrays. Their technique could be used to simulate quantum systems using neutral atoms held in 2D arrays of optical traps.
Optical traps – or tweezers – work by trapping atoms, molecules or small transparent objects near the focus of a laser beam. The technique allows particles to be picked up and moved using just light. They have played crucial roles in manipulating viruses and proteins for medical research and have also been used for assembling tiny nanomachines. Holding cold atoms in arrays of optical traps has also proven very useful to physicists because the arrays can simulate the quantum physics of solid materials. However, creating such arrays of atoms remains a challenge.
Order from disorder
Now, Thierry Lahaye and colleagues have overcome an important shortcoming of optical traps that makes it difficult to use the technique to assemble perfect arrays of single cold atoms.
When dealing with cold atoms, explains Lahaye, “there is a problem in that each optical trap is randomly loaded in an array and so only has a 50% probability of being filled with an atom at any one time.” “Now for applications we ideally want a fully loaded array – that is, one in which each trap has a probability of 100% of containing a single atom,” he says, adding, “although researchers have tried to solve this problem in a number of ways before now, none have been so efficient and versatile as the one we have demonstrated in this work.”
Maxwell’s demon
Lahaye and colleagues’ solution to the filling problem is to sort disordered arrays of atoms into ordered ones using optical potentials. The researchers used a spatial light modulator to create arbitrary 2D arrays of up to 100 traps. Each trap has a radius of around 1 μm and the traps were separated by about 3 μm. The traps were loaded randomly with rubidinium-87 atoms with a filling probability of 50%.
The team then used fast-moving optical tweezers to rearrange the atoms in the disordered array into a pre-defined spatial configuration of their choice (see figure). The team likens the process to how a Maxwell’s demon operates. “Although only the entropy associated with the atomic positions in the arrays is removed,” they explain, “the much higher entropy associated with the motion of each atom in each trap remains unaffected.”
The occupation of the array sites was measured by illuminating the system with light and observing the fluorescence of the rubidium atoms using a CCD camera.
Quantum simulations
The researchers say that the technique could be used to simulate a variety of quantum systems including quantum magnets. “We are now trying to perform these types of experiments using our technique and combine our previous work in which we excited trapped atoms to highly excited (Rydberg) states to simulate the quantum Ising model (which describes idealized magnets),” Lahaye explains. “We are also looking into using our atom-by-atom assembler to perform quantum simulations of ‘frustrated’ magnets, by comparing what happens in different array geometries, such as square and triangular lattices.”
The atom-by-atom assembler is described in Science.
“Asteroid-impact emergency-planning” exercises held by NASA and FEMA
“What would we do if we discovered a large asteroid on course to impact Earth?” That was the scenario being discussed at a recent joint meeting – held by NASA and the Federal Emergency Management Agency (FEMA) – in El Segundo, California. The third in a series of meetings, the two agencies aim to develop and design a way to respond in case of an asteroid impact. “It’s not a matter of if – but when – we will deal with such a situation,” says Thomas Zurbuchen, the recently appointed associate administrator for NASA’s science-mission directorate. “But unlike any other time in our history, we now have the ability to respond to an impact threat through continued observations, predictions, response planning and mitigation.” According to the agencies, exercises such as this one allow the planetary-science community to show how it would collect, analyse and share data about a hypothetical asteroid predicted to impact Earth, while giving emergency managers a chance to discuss how that data would be used to prepare and respond to the threat, as well as warn the public. “It is critical to exercise these kinds of low-probability but high-consequence disaster scenarios,” says FEMA administrator Craig Fugate. “By working through our emergency-response plans now, we will be better prepared if and when we need to respond to such an event.” The scenario simulated during this exercise involved a hypothetical possible impact four years from now – a fictitious asteroid imagined to have been recently discovered, with a 2% probability of impact with the Earth on 20 September 2020. While mounting a deflection mission to move the asteroid off its collision course has been previously simulated, this particular exercise was designed so that the time to impact was too short for a deflection mission to be feasible – and so to pose a great future challenge to emergency managers faced with a mass evacuation of large metropolitan areas. You can read more about these planning exercise’s on NASA’s Planetary Defense portal.
Tiny lasers could boost microscopy
A new microscopy technique that uses micron-sized lasers to illuminate objects from within has been created by researchers in the US and Slovenia. Seok Hyun Yun and colleagues at Harvard University, Massachusetts Institute of Technology and the J Stefan institute in Ljubljana have shown that perovskite nanowires (about 5 μm long and 400 nm thick) can be pumped by a green laser so that they emit their own red laser light. They also created a microscopy system that uses a spectrometer to obtain images using only the laser light emitted by the nanowires. The system could be used to create high-resolution images of biological samples by having cells or tissue absorb the nanowires. This is similar to fluorescence microscopy, which involves adding a fluorescent dye to samples – but Yun and colleagues say the nanowires could offer several advantages over fluorescence microscopy, including superior depth resolution. The nanowires are described in Physical Review Letters and could also be engineered to emit different coloured light, depending on their local chemical environments.
NSF reviewing its funding for Arecibo and Green Bank observatories
Funding woes: Arecibo (left) is located in Puerto Rico, and until the recent completion of China’s Five-hundred-meter Aperture Spherical Telescope (FAST), it long held the title of the world’s largest telescope with its 305 m dish. Green Bank is located in West Virginia within the National Radio Quiet Zone and has the world’s largest fully steerable telescope. (Courtesy: Arecibo Observatory and National Radio Astronomy Observatory)
The National Science Foundation in the US is currently in the process of determining its future level of funding for a bunch of astronomical facilities, mainly the Arecibo Observatory in Puerto Rico and the Green Bank Telescope in West Virginia, US. In reviews carried out over the past decade or longer, both observatories were identified as candidates for funding reductions, largely due to budget constraints that force the NSF to be able to fund other facilities that are thought of as more integral to achieving current astronomy and space-science goals. The NSF is currently carrying out an Environmental Impact Statement (EIS) process to decide both observatories’ fate, before they choose to either make no changes, ramp down funding or “potentially mothball or deconstruct each”. The process began in May for Arecibo and in October for Green Bank, before a final decision will be reached within the next year and a half. Despite various recommendations for reduced funding for Arecibo, Patrick Taylor, group lead for planetary radar at Arecibo, has warned the NSF that “any level of divestment by the NSF of Arecibo, without replacement of that funding from some source, will endanger the NASA-supported work that we do, which is also congressionally mandated, of tracking and characterizing potentially hazardous asteroids.”
You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story.
After enjoying clear blue skies for the first couple of days of my visit to Beijing, the breeze has disappeared and the smog has taken its hold. One local scientist told me this latest wave is due to pollution from factories south-west of the city, but others have told me it is difficult to pinpoint a particular source. Facemasks are being worn by every other person in the streets, but fortunately I’ve been sheltered by the walls and ceilings of Peking University (PKU).
