City Law Warns About Radiation That Probably Won't Harm You

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 The city that begat the Free Speech Movement is getting sued for violating free speech.
 

 In May, Berkeley, California, passed an ordinance requiring purveyors of cell phones to post a notice warning customers that keeping phones in their pockets or bras may expose them to more radio frequency radiation than FCC guidelines recommend—despite the fact that there’s no demonstrated health risk from this form of radiation. CTIA-The Wireless Association, an industry group,
 <a href="http://www.nytimes.com/2015/07/22/us/cellphone-ordinance-puts-berkeley-at-forefront-of-radiation-debate.html?_r=0">
 soon brought the city to court
 </a>
 , claiming Berkeley’s requirement violates the First Amendment rights of retailers by forcing businesses to make statements contrary to their own opinions.
 

 The notice comprises a relatively mild and unexciting part of the
 <a href="http://codepublishing.com/ca/berkeley/">
 Berkeley municipal code
 </a>
 , which among other things mandates up to 30 days in jail for possession of a nuclear weapon, requires medical marijuana dispensaries to give away weed to low-income patients, and has outlawed all Styrofoam containers since 1990. It probably won’t much affect some citizens—for example,
 <a href="http://www.berkeleyside.com/2015/07/18/in-berkeley-protesters-strip-naked-to-try-to-save-trees/">
 these people protesting the removal of invasive trees
 </a>
 , since they weren’t wearing clothes anyway. (Full disclosure: I’m a resident of Berkeley, I use a cell phone, and I wear clothes in public.)
 
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/phonepocket.width-990_c7V92rf.jpg"/>
<figcaption>The increasing utility of smartphones means they are held closely more often.
 
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 Robert Post, dean of Yale Law School, along with Lawrence Lessig of Harvard Law School, are representing Berkeley pro bono. Lessig was unavailable for comment at the time of publication. His office voicemail cheerfully told me, “Hi this is Lawrence Lessig. I’m sorry, I don’t believe in phones. If you want to reach me, it’s best to do so by email.”
 

 But I did reach Post. Calling from his cell phone, he explained that First Amendment claims have also been made against the mandatory posting of fast food calorie counts in New York and a recent GMO labeling law in Vermont.
 

 “They always cite cases that say you can’t compel someone to say the Pledge of Allegiance,” Post says. But courts typically draw a distinction, he says, between speech expressing personal beliefs and so-called “commercial speech” intended to help a business make a profit—the latter does not enjoy the same level of protection. Post harbors a longstanding interest in these kinds of First Amendment cases, which he thinks are “way out of control.” Labeling decisions are legislative ones, he says, not constitutional ones.
 

 Berkeley’s new mandate may or may not be a harbinger of more prominent warnings. Other city ordinances, which were radical at the time they were passed, presaged broader cultural shifts—for example, bans on smoking in public or provision of benefits to same-sex partners. Conversely, many cities still allow the use of Styrofoam take-out containers 25 years after Berkeley enacted the ban.
 

 Though the cell phone ordinance makes no mention of specific health risks—indeed—it merely encourages perusal of existing FCC standards—some of the momentum to pass the initiative came from a group called the California Brain Cancer Initiative, which is adamant that cell phone use increases the risk of cancer despite the fact that scientists have yet to firmly establish any such connection.
 

 Cell phones emit radiation. So do radio station transmitters, light bulbs, and X-ray machines. But not all radiation is emitted equally. Indeed, physicists draw a line between “ionizing radiation,” which is vigorous enough to tear electrons off atoms, and non-ionizing radiation, which is not. Ionizing radiation—like cosmic rays and x-rays—can do rapid and irreversible damage to cells in living things.
 

 But cell phones emit radio-frequency radiation, which falls squarely in the nonionizing category. The FCC points out that the only demonstrated harm from radio frequency radiation happens if you concentrate enough of it on your body to start heating your tissues—an effect
 <a href="https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet56/oet56e4.pdf">
 far beyond
 </a>
 a cell phone’s power, no matter what garment or undergarment you use to hold the device.
 

 Indeed, the World Health Organization, based on data from 25,000 studies, has concluded that “that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields.”
 

 The WHO does point out there are some areas that would benefit from further research. Its cancer research group, the International Agency for Research on Cancer (IARC), classifies radio frequency radiation as a category 2B agent—that is, “possibly a carcinogen.” Dr. Jonathan Samet, director of the University of Southern California Institute for Global Health and the chair of the IARC report on radio frequency radiation, says that one analysis of data in an
 <a href="http://interphone.iarc.fr/UICC_Report_Final_03102011.pdf">
 IARC study
 </a>
 showed a possible association between cell phone use and brain cancer, but whether the link appeared depended on how the analysis was carried out. “The word is ‘possible,’ ” Samet says. “I think that saying what that means is a little challenging.”
 

 So does Samet use a cell phone? “Of course,” he said, “I have not altered my behavior with my cell phone since the 2B classification.”
 

 That classification puts cell phone radiation in with coffee, ginko biloba, and aloe vera extract—all things that are ubiquitous in Berkeley and are
 <a href="http://monographs.iarc.fr/ENG/Classification/vol1_113.php">
 all possible carcinogens
 </a>
 .
 
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 Photo credit:
 <a href="https://www.flickr.com/photos/info_grrl/10023825043">
 Gwyneth Anne Bronwynne Jones/Flickr (CC BY-NC-ND)
 </a>

Friction Fighters

Is friction real? Once, with the quiet certainty of someone who just stayed up all night in the company of equations describing concrete, my college roommate told me that friction was made up.

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 Now, I’m pondering her words as I stare at six yterrbium atoms. They are blue and dancing, projected on the wall of a small room off a long hallway at MIT. Lasers and electronics march all over a wide tabletop, climbing up into the ceiling and slithering down to the floor. I’m about to learn that everything I thought I knew about friction is a 14 th -century work of fiction—and that the truth is stranger by far.


 I’m in the lab of Vladan Vuletic, a professor of physics here, where two of his graduate students are feeding electrical current through a circlet of aggressively coiled wires into a shoebox-sized, airless vault, instructing the ytterbium atoms to move in unison—in time with swing music, even.


 Ytterbium ions move on command in Vladan Vuletic's lab at MIT.


 Vuletic and his lab group spent years setting up this maze of a room in order to study technology so new we’re not quite sure if it really exists yet: quantum computing. But when he realized that their experiment could do much more, his curiosity sent him on an unexpected detour. “We could study friction in a way that was not possible before, namely, have direct access to looking at each atom individually.”


 Friction is a simple word that glosses over a complex phenomenon arising from a dizzying array of interactions. “Friction is a very elusive thing. It’s not something you can touch, but you always feel the effect,” says Ali Erdemir, a senior scientist at Argonne National Laboratory who has spent decades figuring out how to reduce friction losses in transportation. Friction gives and friction takes away. It ensures that our shoes don’t slip and our vehicles stop on command. But friction also eats up roughly one third of all the fuel we burn in our cars, and deep underground, friction between bits of the earth’s crust decides when and where an earthquake will occur.


 Tribologists, the clan of scientists and engineers who study interacting surfaces, think on scales ranging from atoms to airplane wings, and their efforts have huge potential payoffs. In transportation alone, researchers think that reducing the energy lost by surfaces rubbing against each other in engines could save 1% of the all the energy used in the U.S. alone, says Robert Carpick, a professor of mechanical engineering at the University of Pennsylvania.


 For tribologists, the experiments going on right now in Vuletic’s lab could offer a fresh window into a force that’s almost as poorly understood as it is ubiquitous. “In some ways there’s more fundamental physics in our understanding of black holes light years away from us than there is about the friction between our feet and the ground,” Caprick says.

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<h2>
 Laws and Loopholes
</h2>

 Most people’s first encounters with the scientific side of friction are brief and quickly forgotten. Carpick, for example, had no idea friction was a subject of active research until he started working in a tribology lab as a graduate student. Jaqueline Krim, who heads a nanotribology lab at North Carolina State University, says that just two basic laws about friction, wedged into an introductory physics course, comprised “almost 100% of what I learned up to my Ph.D.”


 In fact, those basic two laws go back a long way. “Leonardo da Vinci and the other guy—whose name I don’t actually remember—wrote down the laws by 1600,” says George Smith, a historian of science at Tufts University and mechanical engineer. Da Vinci worked out his rules 200 years before the other guy—Guillerme Amontons—but da Vinci never published. Amontons printed up his laws in 1599, died shortly thereafter at the age of 42, and all but disappeared from history.


 Here’s what Amontons’s laws say: Imagine dragging a reluctant elephant across a parking lot. Suppose this hypothetical pachyderm is stubborn enough to keep all four legs locked in place and all four feet touching the pavement. Once you overcome inertia to get the beast moving, all your effort goes into fighting the friction between the elephant’s hooves and the asphalt. Amontons’s first law says that the friction force is proportional to the force of the pavement pushing against the weight of the elephant. (In physics, this is called the “normal force” because it’s normal—that is, perpendicular—to the surfaces in question.) So if you stack a second elephant on top of the first, you get twice as much friction because you have twice the normal force. (Though the normalcy of the stacked elephant situation is admittedly debatable.) The second law states that friction doesn’t depend on how much area is in contact. So if your elephant daintily lifts up one of its front legs, and one of its back legs, the friction doesn’t change, even though there’s only half as much hoof area touching the ground.


 Amontons’s laws do a reasonably good job of describing many everyday situations, but they are nonetheless fiction. They fall short because they don’t really tell us anything about what’s going on between two sliding surfaces. The closer we look, the more loopholes tribologists are finding in Amontons’s laws.


 For example, let’s take a second look at the second law. If friction comes from interactions between two surfaces, then wouldn’t more surface mean more opportunities for things to catch and snag against each other and thus more friction? “This is something that always intrigued me, you know,” Vuletic says. “It turns out that even this is not perfectly well understood.”

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 Amontons’s laws do a reasonably good job of describing many situations, but they are nonetheless fiction.

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 Or take this other example: Which is easier, dragging a box across an ice rink or a soccer field? You might expect that smoother surfaces like ice always slide more easily than rough ones like grass. But this is not always true. If you take two copper surfaces and polish them to perfection, then the copper refuses to slide at all. “When the atoms in contact are all of the same kind,” explained the physicist Richard Feynman in one of his lectures, “there is no way for the atoms to ‘know’ that they are in different pieces of copper.”


 Yet another unsolved tribology mystery involves a Soviet physicist named J.W. Obreimoff, who in 1929 was using a Gillette razor to slice rock the hard way. He cut into a thin sheet of mica, blade parallel to the glittery surface. As he sliced Obreimoff saw what he described as a “splash of light.” To this day, neither Amontons’s laws nor any other description of interacting surfaces can explain the phenomenon, says Seth Putterman, a professor of physics at UCLA. Yet it’s everywhere. The same physics is at work when you crunch down on a wintergreen-flavored Lifesaver candy and see sparks or when a cat’s fur crackles with static electricity after it walks across carpet. “For sure we don’t understand the cat’s fur,” Putterman says.


 A Rough Place


 Our partial ignorance may really be an issue of scale. If you zoom in enough, the seemingly smooth surface of an ice sheet or mirror would resemble a mountain range. “Atomically speaking, there’s no such thing as a flat surface,” says Michael Strano, a professor of chemical engineering at MIT. When you slide one surface over another, it’s like you’ve turned the Himalayas upside down and started dragging them across the Rocky Mountains. The peaks, called “asperities” in tribology lingo, bump into each other. Each time they stretch, compress, or break off saps energy from the motion.


 The rough nature of smooth-looking surfaces could help explain why the second law of friction suffices for macroscopic objects but breaks down if we zoom close enough. Most of what we measure as an object’s surface area (say, the elephant foot) doesn’t interact with the other surface (say, the pavement). In fact, only a few atoms at the tops of the asperities in the foot get close to the tops of the asperities in the pavement. These are the only atoms that “actually see each other,” Erdemir says. “
 
 They
 
 are intimately interacting.”


 If we could master those interactions, we might be able to get rid of friction.


 Researchers theorized in the late 1980s about how to eliminate one type of friction, known as stick-slip. Stick-slip friction happens when the peaks of one surface nestle down into the valleys of the other and get stuck—until you apply enough force to coax them up and out. In many cases, it’s the dominant frictional effect at atomic scales.


 The trick to overcoming stick-slip is to induce apathy, convincing the two surfaces not to give a damn if you move them across one another. Such surfaces are called “incommensurate.” To picture incommensurate surfaces, suppose we papier-mâchéd over one-inch round marbles spaced exactly one inch apart. To make the second surface incommensurate with the first, we papier-mâché over more marbles to make a surface that can’t mesh with the first one . That means making the space between the marbles in the second surface different. (Not just any spacing will do—if the new bumps are exactly two inches apart, then the surfaces will still fit together, with every other peak corresponding to a valley. For the surfaces to be incommensurate, the ratio of the spacing must be an irrational number, which cannot be written as a ratio of integers. A ratio of π would work, but ratios of 17 or ⅓ would not, because then every 17 th atom or every third atom would line up with atoms in the other surface.)


 If you build two incommensurate surfaces, no matter how you shove them around, “you’ll always have some fitting and some not fitting,” says James Hone, a professor of mechanical engineering at Columbia University. If the surfaces can interlock, they’ll prefer the stuck-together arrangement. But for incommensurate surfaces, apathy sets in. “Then the system doesn’t care if it’s moving sideways,” he says, so you don’t lose energy as you move. If done right, the two incommensurate surfaces might slide past one another with vanishingly low friction. Such surfaces are especially intriguing to the materials scientists, physicists, and engineers that have spent the last 25 years trying to observe frictionless sliding, a phenomenon known as superlubricity. Some argue they’ve already found it.


 Vanishing Act


 In an airless chamber in the center of the lab, Alexei Bylinskii, a graduate student in Vuletic’s group, uses electric fields to corral a handful of ytterbium ions into a space the size of a matchbox. By changing the electric current flowing through the maze of wires, they can carefully pull these atoms over a surface below and measure how much friction the atoms feel.


 This lower surface, which is designed to be incommensurate with the string of ytterbium ions above, is called an optical lattice. It is made out of light but that doesn’t mean the surface is an illusion. By bouncing light between two mirrors, the group creates a standing wave of light—imagine the peaks and troughs of a frozen ocean wave. These peaks and troughs correspond to points of higher and lower energy for the ytterbium ions, which want to move down into troughs and away from peaks. From the ion’s point of view, this landscape resembles the high and low points on the surface of a material like copper—but the scientists can control the shape and size of the optical lattice far more precisely than they can control the surface of a physical chunk of metal. When Vuletic’s lab rigged the spacing of the ions to be incommensurate with the spacing of the optical lattice below, they observed a dramatic reduction in friction.


 Even outside this pristine vacuum chamber, researchers have created systems with incredibly low friction. Ali Erdemir and colleagues at Argonne National Lab recently created a surface coating that resembles miniscule ball-bearings. The “ball-bearings” are actually tiny diamonds, wrapped up in a wispy layer of graphene to produce two incommensurate—and incredibly slippery—surfaces. Erdemir calls the work a clear example of superlubricity.


 But some tribologists argue the term is misapplied—“you might call it very good lubricity, not superlubricity,” Carpick says. In physics, the prefix “super-” typically applies only in extreme situations. Sokoloff explains that when researchers observe superconductivity, current flows unhindered because “electrical resistance really does go down to zero.” Similarly, when liquid helium exhibits
 <a href="https://www.youtube.com/watch?v=2Z6UJbwxBZI">
 superfluidity
 </a>
 , its viscosity vanishes, allowing the stuff to eerily climb up and over the walls of its container. So far, superlubricity experiments have demonstrated very low—but not actually zero—friction.


 The terminology dispute hints at something deeper than a quibble over nomenclature. The theoretical picture of superconductivity relies on quantum mechanics. Superfluidity also defies classical physics. So will quantum mechanics help us understand where to look for “true” superlubricity?

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 Not necessarily, Sokoloff argues. “Right now, according to the way we understand things…you’re probably not going to see truly zero friction,” Sokoloff says.


 Scientists don’t yet know what role quantum mechanics might play in friction on the atomic scale. Vuletic’s lab is working on cooling their experiment down to just a hair above absolute zero, where they hope to see ytterbium ions quantum tunneling—moving through the peaks, rather than over them. They want to see how this quantum tunneling affects friction, an observation that may help us understand friction at larger scales. But it’s not a done deal, Bylinskii says. “Whether friction in the real world depends on quantum mechanical effects, that’s an open question.”

<h2>
 Sliding Forward
</h2>

 If answering that and other questions would be helpful to traditional mechanical engineers, it would be a breakthrough for nano engineers. At large scales, we’ve come up with shortcuts to make friction less destructive. Take a car tire. On average, every revolution on pavement wears off one layer of atoms, Vladan Vulutec says. “For a tire it doesn’t matter, because there’s billions and billions of layers until you have a millimeter or centimeter of loss of profile.”


 But as researchers design devices that are only 100 or even ten atoms thick, and losing even one layer of atoms is a pretty big deal. “Nanoscale stuff is all surface,” says Hone, the Columbia nano engineer, “and so once you contaminate the surface, you’ve changed what it is.”


 Back at MIT, Strano’s group is interested in scaling up nanoscale discoveries about friction and other phenomena to make exotic materials for safer, lighter cars and airplanes The potential applications are huge: Ali Erdemir of Argonne estimates that mitigating friction losses in transportation alone could save an estimated $500 billion in fuel costs and 800 million tons of CO­­ 2 annually.


 Mastering friction could also help make cars safer. When a car crashes, several thousand of pounds of mass that were moving suddenly aren’t anymore. As the energy of motion dissipates, the frame of the car—not to mention the occupants—often crumple up. “You’d like to flow that energy in a certain way, and you’d like it not to go to you,” Strano says. Controlling atomic-level friction could help design a material that’s rigid in most cases but bends easily when pushed from a certain direction, allowing designers to carefully orchestrate how the frame of a car deforms in the event of an accident.


 All of the researchers I talked to say they’re a long way from completely eliminating or even expertly controlling friction in the messy world outside the laboratory. Strano points out that, in general, researchers observe amazing properties on atomic scales, but they have made slower progress in advancing tantalizing technologies like ultra-efficient engines or futuristic airplane wings.


 But that hasn’t stopped them. “It used to be that friction was okay if your car wasn’t wearing away,” says Krim, the nanotribologist. “Our world is less tolerant now of waste.”


 Photo credits: Sauliakas/iStockphoto,
 <a href="https://www.flickr.com/photos/16366828@N07/3487448790/">
 John Town/Flickr (CC BY-NC-ND)
 </a>
 , Sam Stulin

Mastering the poorly understood yet ubiquitous force could transform everything from transportation to geology.

The Undamming of America

We’ve impounded rivers for hundreds of years, but as our society has evolved, so has our relationship with dams.

Injectable Mesh Electronics Could Someday Interface with Your Brain

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 The mesh unrolls like a loosed parachute—not into thin air but rather into the brain of an unconscious mouse.
 

 Delivered from the tip of a syringe, the device is woven from supple, electricity-conducting fibers half as thick as a human hair. Nestled among neurons deep within the mouse’s gray matter, this nanowire fabric gives researchers at Harvard University a way to record—and even alter—the ebb and flow of signals to individual neurons in a living brain.
 
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/injectable-electronics.width-990_C8HHLDv.jpg"/>
<figcaption>Flexible electronics can be delivered via syringe.
 
 </figcaption>
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 To understand how the brain works, researchers need ways to measure it in action. Tracking the fine-grained firing of individual neurons is a tantalizing yet unrealized path to answering big questions about the complex workings of the brain. Electrodes in direct contact with brain cells can take precise measurements, but traditional rigid electronics are cumbersome and invasive.
 

 The Harvard team’s flexible, 2D mesh consists of strands of polymers organized in a fishnet-like pattern. At each crisscross, there’s a tiny electrical component to send or receive signals. Unrolled, the mesh is roughly 20 times as wide as the size of the opening from which it emerged. The researchers recorded from 16 individual neurons in the hippocampus, a brain region associated with spatial recognition, to verify their device. They also used the injected mesh to send signals to individual neurons. Here’s Elizabeth Gibney, reporting for Nature News:
 
<blockquote>

 The implant has the potential to unravel the workings of the mammalian brain in unprecedented detail. “I think it’s great, a very creative new approach to the problem of recording from large number of neurons in the brain,” says Rafael Yuste, director of the Neurotechnology Center at Columbia University in New York, who was not involved in the work.
 
</blockquote>

 The Harvard group observed their wired-up mice for five weeks after the mesh injection, watching out for possible immune responses to the foreign material in the mouse brains. They are hopeful the technology may indeed be extended to record many more neurons over much longer periods of time.
 

 At present, researchers have a direct line to a dozen or so cells in the brains of unconscious mice, but they have even bigger dreams for future developments. Though much more testing is needed, this technology may someday allow the researchers to stimulate individual neurons therapeutically, counteracting the ravages of strokes or diseases like Parkinson’s.
 
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 Photo credit: Lieber Research Group, Harvard University

Putting a Price on Nature

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 I’ve done the math, and for $1.20, you can preserve a 19-inch by 19-inch square of rainforest habitat—home, on average, to 0.000006 long-tailed macaques and 0.0000001 pangolins. All you have to do is pay a bit more for palm oil, found in roughly half of all grocery store items: chocolate bars, cereal, and lipstick, to name a few.
 

 “Most people probably consume some palm oil every day,” says David Wilcove, a professor of ecology at Princeton University. The ubiquitous stuff is squeezed from the fruit of trees whose rapidly expanding cultivation has infamously contributed to widespread deforestation in southeast Asia, and increasingly, parts of South America and Africa.
 
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<img alt="Indonesia, 2007." class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/palm-oil-plantation.width-990_hET12Q0.jpg"/>
<figcaption>A palm oil plantation in Indonesia
 
 </figcaption>
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 I
 <a href="http://nbviewer.ipython.org/gist/anonymous/7ec291a0dece212110f1" target="_blank">
 derived the numbers
 </a>
 above from a study appearing this week in the
 
 Proceedings of the National Academy of Sciences
 
 (
 
 PNAS
 
 ), part of a collection authored by over 80 researchers from 50 institutions spanning ten different countries. The collection examines the tangible value people derive from ecosystems and natural processes—a concept known as “natural capital.”
 

 Natural capital is a catch-all concept that covers everything from crop pollination by bees to the water-cleansing properties of wetlands. Consider a coastal mangrove forest, for example, says Jane Lubchenco, professor of marine studies at Oregon State University and one of the editors of the collection. “A lot of people think of mangrove forests as dirty, mosquito-infested places that might as well be converted into something useful,” she says, but in fact mangroves provide many unrecognized benefits. These include taking up toxic runoff, providing habitat for wildlife (including seafood humans later eat), removing carbon dioxide from the atmosphere, and protecting shorelines from storm surges and erosion.
 

 Natural capital can be found all around the globe, from coastal flats to rain forests and alpine watersheds. In a world where money neither grows on trees nor has done much to incentivize their protection, researchers are figuring out how to put price tags on forests, rivers, and wild animals. Many consider this process a necessary element of 21
 
 st
 
 century conservation.
 

 Authors of the new palm oil study wondered if producers might be able to turn a profit while also helping wildlife. The researchers asked people how much more they would be willing to pay for palm oil if they knew it came from plantations that preserve some land as rainforest. They found that people would be willing to shell out 15–36% more for “conservation-grade” palm oil. At the low end, an 80,000-acre plantation could still make a profit while leaving roughly one-sixth of its land unplanted.
 

 Then the authors used mathematical models to determine how the conserved areas might aid threatened species, including long-tailed macaques, gibbons, and pangolins. Using their data, I ran the numbers on how much land—and how many wild critters—a hypothetical purchase of 16 fluid ounces of palm oil
 <a href="#fn1-2015-06-18" id="fnr1-2015-06-18">
 ¹
 </a>
 would contribute. A bit of rainforest the size of a manhole cover would add an additional $1.20 to the purchase.
 
<aside class="pulledquote">
 At the low end, an 80,000-acre plantation could still make a profit while leaving roughly one-sixth of its land unplanted.
 </aside>

 On one hand, that may not seem like a lot. But among price-conscious consumers—and, more importantly, companies that use palm oil in their products—a 15% price hike is not insignificant. Which raises a question: will assigning cash value to the natural world be enough to save it?
 

 “Pricing nature alone won’t, in itself, do anything to improve the way we actually manage resources,” says Gretchen Daily, a professor of biology at Stanford University who coauthored several papers in the
 
 PNAS
 
 collection. Daily emphasizes that, in natural capital accounting, economics are just part of a complex balance sheet that also considers cultural, educational, community values.
 

 That said, the money matters. “Fundamentally, a lot of the decisions in conservation are economic ones,” says Robin Naidoo, senior conservation scientist at the World Wildlife Fund and coauthor on the palm oil study. “We can do a better job as conservationists if we understand that and we use techniques from economics.”
 
<h2>
 Decades in the Making
 </h2>

 The general concept behind natural capital is not new—pollinating insects, for example, have long been recognized as economically important—but only recently have people started systematically calculating dollar values for bees, birds, and even smelly mangrove forests.
 

 “Ten years ago, this stuff was kind of a glimmer in a few people’s eyes,” says Anne Guerry, lead scientist at the Natural Capital Project at Stanford University and coauthor on several papers in the
 
 PNAS
 
 collection. That began to change when, in 2005, thousands of scientists had just completed a project called the Millennium Ecosystem Assessment at the request of the United Nations. This seminal study catalogued benefits that nature provides for people, including “ecosystem services” such as clean water, clean air, cycling of nutrients like carbon and nitrogen, and buffering against floods or erosion. The assessment showed that the majority of these were in decline.
 
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/sundarbans.width-990_MfRrGYb.jpg"/>
<figcaption>Extensive mangrove forests in the Sundarbans protect the region from coastal flooding.
 
 </figcaption>
</figure>

 In 2005, there was only one practical example of applying dollar value to ecosystem services, Guerry says, and even that was almost a decade old. In 1996, rather than build a purification plant, the city of New York decided to restore an upstream watershed in the Catskills—which provides most of the city’s water supply. Two years later, in a commentary in
 
 Nature
 
 , Columbia economists Geoffrey Heal and Graciela Chichilnisky estimated the Catskill project saved the city $6 billon. The project and the paper helped cement the idea of natural capital.
 

 Now, Guerry says, there are hundreds of stories of accounting for or discovering ecosystem services. For example, one study in the
 
 PNAS
 
 collection describes how a coastal development plan in Belize prioritizes both wildlife habitat and development revenue. In another, researchers found that environmental protection in a part of the Brazilian Amazon was associated with reduced instances of diseases like malaria among inhabitants.
 
<h2>
 Calculating Conservation
 </h2>

 The process of assigning dollar value to something like an intact forest often begins with a crisis. Daily describes how, in the late 1990s, deforestation across China had increased the risk of severe flooding. “Forests soak up rainfall, like a sponge, gradually releasing the water. Without them, you put millions of people at risk,” she says. In 1998, catastrophic flooding on the Yangtze River drowned thousands of people and millions of homes, causing $40 billion in damage. The scale of this disaster provided an estimate for valuing ecosystem services: China has now implemented a $150 billion program to protect and restore forests.
 

 “Nature is often a hell of a good engineer,” says Jonathan Foley, director of the California Academy of Sciences, who was not directly involved with the
 
 PNAS
 
 work. “It’s often cheaper and better to let nature do work for us.”
 

 Science has advanced a great deal in understanding not only what nature contributes, Guerry says, but also how, when, and where these contributions take place. Yet even as the science leaps ahead, the implementation often lumbers. Lost natural capital is usually an externality, or what economists call a price paid by a third party who never had a choice in the matter. For example: suppose a farmer in the Iowa applies fertilizer to his fields. As this fertilizer washes into rivers flowing west, it degrades water quality and contributes to algae blooms that diminish the oxygen available to fish. Everyone downstream pays—from a town treating drinking water to an empty-netted fisherman in the Gulf of Mexico. “The failure isn’t about the environmental science, really, but more in economic theory,” Foley says.
 
<aside class="pulledquote">
 “Nature is often a hell of a good engineer.”
 </aside>

 Accounting for externalities can be challenging. “Ecosystem services and natural capital are still in the Wild West phase,” says Steve Polasky, a professor of ecological and environmental economics at the University of Minnesota and editor of several of the
 
 PNAS
 
 studies. There is no single, standard way of valuing something like water or habitat. And biodiversity is difficult to price because it’s a form of infrastructure, like an airport, that underpins a lot of other benefits. Take the airport by way of analogy. It has direct value—in the land it occupies, for example, and the rent it charges—but it also brings in people and goods that might not otherwise come to the city. Quantifying the indirect value can be incredibly difficult. Sorting out how much revenue at a certain restaurant should be attributed to the nearest airport—or to how much that restaurant stands to lose if the airport closes—is no simple task.
 

 In the same way, changes in the number and variety of plants and animals may have complex effects on ecosystem services. For example, researchers studying a Minnesota grassland found that increased biodiversity was associated with more of what ecologists call productivity, or the total mass of all the insects, grasses, birds, worms, dead leaves, and so on. A productive ecosystem stores carbon and nutrients, which can decrease atmospheric carbon and improve water and soil quality, for example. Declines in productivity would cascade through each of those services.
 
<h2>
 Hard Numbers
 </h2>

 When it comes to protecting biodiversity threatened by palm oil deforestation, Wilcove argues that even after including natural capital, the economic argument alone is going to be a tough sell. Wilcove, who is unaffiliated with the recent
 
 PNAS
 
 collection, estimates that if you cut down an acre of undisturbed tropical rainforest in lowland Borneo, sell the timber, plant palms, and sell all the oil you can harvest, the present value of that one acre is $54,000. If you leave the forest undisturbed, he says, “you don’t recover anything close to that amount,” even after adding up contributions from carbon sequestration, watershed protection, biodiversity, and tourism. You come up at least $25,000 per acre short.
 

 Furthermore, these valuations may not be enough to help a severely threatened species like the Sumatran tiger, whose global population is down to 400. Wilcove points out that rare species, “almost by definition,” are unlikely to contribute to human economic activities a substantial amount and thus don’t fare well in a in a purely economic calculation. He notes, however, that natural capital may still be a useful supplement—say, if the tiger inhabits a watershed that provides clean drinking water to people downstream. And as the
 
 PNAS
 
 study showed, when consumers are willing to pay more for the principle of protecting wildlife—which some are—producers could find it economical to restore habitat or even leave it intact from the start.
 

 Still, the palm oil case illustrates the difficulties of tackling global environmental problems. Only 2% of the world’s palm oil goes to the U.S., whereas half is consumed either in India, China, or Indonesia. A 15% price increase might not be tenable in these emerging economies.
 
<h2>
 What’s It Worth?
 </h2>

 So is assigning value to wild forests or free-roaming gibbons going to halt the palm oil crisis? The answer, as you might expect from something tangled up with everything from fuzzy animals to atmospheric carbon to the price of cornflakes, is that it’s complicated.
 

 The researchers I spoke with assert that the idea of natural capital has already worked for both people and nature—coastal protection has stabilized fisheries in Belize and wildlife conservation is benefiting local economies in Namibia, for example. They firmly believe that more success stories are on the horizon.
 
<figure class="richtext-image full-width">
<img alt="oil palm kernels" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/oil-palm-kernels.width-990_7km12x6.jpg"/>
<figcaption>Oil palm kernels
 
 </figcaption>
</figure>

 For his part, Polasky describes himself as “pragmatically optimistic.” An economist by training, he recalls the tension when he walked into a in a room full of conservationists, many of whom have been averse to assigning any dollar value to nature. Indeed, if one considers the last few Sumatran tigers to be priceless, assigning a value—no matter how high—only makes them cheaper. But Polasky believes that there’s been somewhat of “a detente between economics and conservation, and there’s great power in bringing them together.” Daily echoes his optimism, and even Wilcove, who remains skeptical on some fronts, says he is “stubbornly and cautiously optimistic.”
 

 Already, the idea of natural capital has spread beyond the small community of academics who coined the term. In 2006, China made a commitment to measuring a “green GDP.” Large corporations like Dow and Unilever have issued public statements committing to ambitious ecological goals in addition to their economic targets. Daily points out that some of these stances, like the green GDP, “might sound ridiculous, but ten years ago, we didn’t have anybody saying anything like this.”
 

 Just last month, in an open letter encouraging higher sustainability standards for palm oil producers, major corporations including Walmart, Starbucks, and ConAgra, and various investors wrote that they “recognize that protecting forests and upholding human rights are essential for long-term business models.”
 

 Today, Polasky says acceptance of natural capital is similar to where life-cycle analysis was several decades ago. The technique, which catalogs every impact a product has on the world, from the source of its raw materials to how its disposed when it stops working, was originally considered a messy, intractable idea with no practical applications. Now, Polanksy says, businesses use it all the time. With more research and standards, he thinks accounting for natural capital will be just as common.
 

 Despite that, many of the researchers stress that economic valuation shouldn’t always be the last word on conservation. When trying combine wildlife, nutrient cycles, human welfare, and market pressures on the same balance sheet, there’s bound to be some confusion. As Foley puts it, “Whether a dollar figure is always the correct unit of measure, I’m not always sure. That’s kind of tricky.”
 
</section>
<ol>
<li>
 Thanks to Associate Professor Lian Pin Koh of the University of Adelaide for estimates of per-acre palm oil production.
 <a href="#fnr1-2015-06-18">
 ↩︎
 </a>
</li>

 Photo credits:
 <a href="https://www.flickr.com/photos/cifor/5701880395/">
 CIFOR/Flickr (CC BY-NC-ND)
 </a>
 , NASA,
 <a href="https://www.flickr.com/photos/1village/2871349212/">
 oneVillage Initiative/Flickr (CC BY-SA)
 </a>

</ol>

The balance sheet might be the next frontier for conservation, but will it be enough to save our ecosystems?

By analyzing the hi-hat in a hit single, physicists demonstrate a uniquely human way of keeping a beat.

1980s Pop Song Reveals Fractal Rhythms of the Human Mind

Pop music in the 1980s was full of weirdness, but no amount of Madonna or
 <a href="https://www.youtube.com/watch?v=nM4okRvCg2g">
 “The Safety Dance”
 </a>
 will prepare you for what scientists recently found in a Michael McDonald song—fractals.

<div class="ad"></div>

 Physicist Holger Henning and colleagues at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany found self-similar patterns in the drum pattern of a recording of the 80s hit song “I Keep Forgettin’.” This pop classic features drummer Jeff Porcoro, who was a member of Toto and has played for other big names like Steely Dan, Madonna, and Pink Floyd.



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 Loosely speaking, a fractal pattern is distinctly recognizable no matter how much you zoom in or out, a property known as self-similarity. For example, if you show a pattern to a person looking through a microscope and to an astronaut looking down from orbit with a telescope, and they describe the same thing, then that pattern is self-similar. Fractal patterns show up both in mathematics and nature, from the intricate contours of the
 <a href="https://en.wikipedia.org/wiki/Mandelbrot_set#/media/File:Mandel_zoom_00_mandelbrot_set.jpg">
 Mandelbrot set
 </a>
 to the mesmerizing florets of the broccoli-like vegetable
 <a href="https://en.wikipedia.org/wiki/Romanesco_broccoli#/media/File:Fractal_Broccoli.jpg">
 romanesco
 </a>
 . Scientists recently noticed that when people make musical rhythms, the resultant pattern of sound has a fractal nature.


 The signature rhythm in “I Keep Forgettin’” comes from Porcaro’s handiwork on pedal-operated cymbal known as a “hi-hat.” Porcaro fires off four “hi-hats” per beat, for a total of nearly 1,000 hi-hats by the end of the song. The study authors analyzed the distinctive sound of a hi-hat in order to filter out all the other instruments. They then looked at two properties of the pattern of hi-hats: the spacing between hits, and how loud each hit was.


 Here’s Kerry Klein, reporting for Science News:

<blockquote>

 Both the intervals between sixteenth notes and their volumes wavered throughout the piece. Moreover, those variations were similar on time scales ranging from a few seconds to the length of the entire song (3 minutes and 39 seconds), showing that the pattern formed fractals, the researchers reported on 3 June in PLOS ONE. “It seems that the timekeeper in the brain not only produces fractal timing,” Hennig says, “but likely also fractal intensity or, in this case, loudness.”

</blockquote>

 Hennig and his team found that both the intervals and volumes could be described by a fractal pattern called “1/f noise.” In this kind of noise, each octave carries the same amount of energy per unit time. The description is sometimes referred to as “pink noise” because visible light whose spectrum has this property is a pink color. The self-similarity comes up in how the pause between two hi-hats depends on the pauses already played. If the size of the space between two hi-hats is just as correlated with the five preceding spaces as it is with the preceding 50 or 500—that is, if it depends on the entire song so far—then the pattern of pauses is self-similar. The loudness followed the same idea.


 What’s more, the loudness and spacing were independent of each other, suggesting Porcaro was controlling them separately. The work, a glimpse into the brain of a talented and prolific musician, offers a fascinating picture of what makes human music human.

<div class="newsletter"></div>

 Photo credit:
 <a href="https://www.flickr.com/photos/29143375@N05/3834566855/">
 Gamma Ray Productions/Flickr (CC BY-SA)
 </a>

By analyzing the hi-hat in a hit single, physicists demonstrate a uniquely human way of keeping a beat.

Long-Lasting "Spaceballs" Solve Century-Old Astronomy Puzzle

<section class="entry-content instapaper_body clearfix" itemprop="articleBody">
<div class="add-container clearfix" id="add-block-placer">
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 Nearly 100 years ago, a graduate student named Mary Lea Heger observed contaminated starlight. As the light traveled to her telescope, it was interacting with great clouds of—something—in the spaces between stars. No one could figure out what that something was, until now.
 

 When you pass sunlight through a prism, it separates into different colors, which correspond to different wavelengths. Astronomers like Heger often analyze incoming light by looking at something called a spectrum, which is a bit like looking at the colorful end of a prism. A spectrum shows you the relative strengths of the different wavelengths of the light comprising your sample. If the light interacts with something before it gets to you—say, a cloud of gas, the spectrum will change, because the gas absorbs some wavelengths more than others.
 

 Heger’s spectra had an unusual pattern that didn’t match any known substances, so no one could figure out what those interstellar clouds were made of. The spectra, referred to as “
 <a href="https://en.wikipedia.org/wiki/Diffuse_interstellar_band">
 diffuse interstellar bands
 </a>
 ” (DIB), remained mysterious for many decades.
 

 In 1983, scientists accidentally discovered a strange molecule called
 <a href="https://en.wikipedia.org/wiki/Buckminsterfullerene">
 buckminsterfullerene
 </a>
 . Commonly known as a “buckyball,” this substance consists of 60 carbon atoms in a soccer-ball shaped arrangement. John Maier, a chemist at the University of Basel in Switzerland, and his collaborators suspected that buckyballs might be part of the strange signal coming from Heger’s interstellar medium, but they needed to know how buckyballs behave in space—a challenging thing to measure here on Earth.
 
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/buckyballs-space.width-990_Jbu7gIR.jpg"/>
<figcaption>Buckminsterfullerene
 
 </figcaption>
</figure>

 Here’s Elizabeth Gibney,
 <a href="http://www.nature.com/news/buckyballs-in-space-solve-100-year-old-riddle-1.17987">
 reporting
 </a>
 for Nature News:
 
<blockquote>

 Maier’s team analysed that behaviour by measuring the light-absorption of buckyballs at a temperature of near-absolute zero and in an extremely high vacuum, achieved by trapping the ions using electric fields, in a buffer of neutral helium gas. “It was so technically challenging to create conditions such as in interstellar space that it took 20 years of experimental development,” says Maier.
 
</blockquote>

 Maier’s team published the work in the journal
 
 Nature
 
 this week, helping to shed light on what the
 
 Nature
 
 commentary calls “one of the longest-standing mysteries of modern astronomy.” Not only do the results show that Buckminsterfullerine comprises some of the mysterious interstellar medium, but they also suggest these “spaceballs” are stable enough to last millions of years as they wander far and wide through space.
 
</section>

 Photo credit: NASA Spitzer Space Telescope

Anna Lieb

Articles