Nearing Certainty About Heisenberg's Uncertainty... Or Not

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  One of the basic tenets of quantum mechanics is Heisenberg’s uncertainty principle, which states that the more precisely one measures a particle’s momentum, the more uncertain its position becomes. The reverse is also true, which means that in theory, it’s impossible to know the exact position and momentum of a subatomic particle at the same time.
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<p>
  Heisenberg originally used the principle to show that there is a limit to the accuracy of particle detectors, but he never offered direct evidence to support his ideas. Now, UK physicist Paul Busch and his colleagues believe they have a proof. Here’s Ron Cowen, writing for Nature:
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<p>
   In their theoretical work, Busch and his colleagues imagined making simultaneous measurements of a particle’s position and momentum in an arbitrary quantum state. They compared the errors in such measurements to two special cases — in which either the position or the momentum of the particle is well known. They found that the combined errors in measurements of the position or momentum in these two cases obeyed Heisenberg’s principle and was always smaller than for cases in which the two properties were measured simultaneously. This step allowed them to prove Heisenberg’s original conjecture.
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<p>
  Scientists remain skeptical, though. Read the
  <a href="http://www.nature.com/news/proof-mooted-for-quantum-uncertainty-1.13270" title="full article">
   full article
  </a>
  to learn more about one physicist’s objection to Busch’s proof, as well as what those doubts mean for quantum computing. For some background on quantum computing, hear from
  <a href="http://www.pbs.org/wgbh/nova/tech/quantum-computing.html" title="MIT's Seth Lloyd">
   MIT’s Seth Lloyd
  </a>
  . And for some comic relief, watch this video:
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  Quantum mechanics is nothing to laugh at. Well, sometimes it is.
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Google Balloons Send Internet Soaring Through the Clouds

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<p>
  Jon Brodkin, writing for ArsTechnica:
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<p>
   Google this week launched 30 balloons into the stratosphere in the first step toward creating what it calls a “network in the sky” that could eventually bring “balloon-powered Internet [to] everyone.”
  </p>
<p>
   Dubbed “Project Loon,” Google’s balloon-based wireless networks aim to bring 3G-like speed to what Google says are the “2 out of every 3 people on Earth” who lack a fast, affordable Internet connection. Google’s plan has been rumored for weeks. As we
   <a href="http://arstechnica.com/information-technology/2013/06/googles-balloon-based-wireless-networks-may-not-be-a-crazy-idea/">
    wrote earlier this month
   </a>
   , balloon-based communications are well established for military communications and have been proposed for public safety use in disaster areas. Google could be the first to make balloon-based networks widely used for commercial Internet access.
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<p>
  One of the key hurdles Google had to surmount was how to maintain coverage with a fleet of balloons that is, at least partially, at the mercy of the winds. They solved it like they have many other problems—by throwing massive amounts of computing power at it. That way each balloon can piggyback on air currents, and when the winds aren’t in its favor, nudge the craft onto a favorable course.
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<img alt="Project Loon" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/google-balloons.width-990_MOc45IA.jpg"/>
<figcaption>Google is not the first to pursue balloons as vehicles for commercial Internet access, but its use of wind and solar power to direct their paths is innovative.
        
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<p>
  Discover how Google dreamt up this way to access the cloud through technology held aloft
  <em>
   in
  </em>
  the clouds:
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<p>
 Photo credit:
 <a href="http://www.flickr.com/photos/ilitephoto/9052643301/sizes/l/in/photolist-eMXasV-8367w1-8369Jd-81JAH3-81JzpW-81JA6w-81FrFK-81FtLe-81JCL1-81JzLb-81EsMc-83zxqq/">
  iLighter/Flickr
 </a>
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Why Naked Mole Rats Don't Get Cancer

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  When a group of researchers at the University of Rochester in New York tried growing skin cells from naked mole rats in lab flasks, they noticed that the fluid the cells were growing in became thick and syrupy. After some investigation, they discovered that the cells, like other cells of mammalian connective tissue, were secreting a sugar called hyaluronan, except the naked mole version was five times bigger. Andrei Seluanov, who led the study, believes that larger hyaluronan can trap potential cancer cells and prevent them from growing into tumors. Writes Ed Yong for Not Exactly Rocket Science:
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<p>
   But it also allows cells to stop each other from growing if they become too crowded. This is called ‘
   <a href="http://www.ncbi.nlm.nih.gov/pubmed/19858485">
    contact inhibition
   </a>
   ’—it’s why healthy cells form a flat layer if they’re grown in a dish but cancerous ones pile on top of each other.
  </p>
<p>
<a href="http://www.nature.com/news/blind-mole-rats-may-hold-key-to-cancer-1.11741">
    Based on an earlier study
   </a>
   , Seluanov’s team suspected that naked mole rat cells are protected against cancer because they’re especially sensitive to contact inhibition. Now, they’ve shown that large hyaluronan is responsible. The rodents’ cells are very receptive to the sugar; as they get close, hyaluronan sticks to their surface and triggers a genetic programme that stops them from growing.
  </p>
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<p>
  The team switched on cancer genes in naked mole rat cells and transplanted them into mice. No cancer. But when they reduced the amount of hyaluronan created by the naked mole rat cells in the mice, tumors formed.
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Scientists Take Global Warming's Temperature

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  By how many degrees would the average temperature of the Earth rise if carbon dioxide levels doubled? Scientists have been pursuing an accurate estimate of this figure since the late 19th century—it’s the “holy grail of climate science,” writes Justin Gillis in
  <em>
   The New York Times.
  </em>
  Most experts believe that this “climate sensitivity” figure lies somewhere just above five degrees Fahrenheit.
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   That may not sound like a particularly scary number to many people — after all, we experience temperature variations of 20 or 30 degrees in a single day. But as an average for the entire planet, five degrees is a huge number.
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   The ocean, covering 70 percent of the surface, helps bring down the average, but the warming is expected to be higher over land, causing weather extremes like heat waves and torrential rains. And the poles will warm even more, so that the increase in the Arctic could exceed 10 or 15 degrees Fahrenheit. That could cause substantial melting of the polar ice sheets, ultimately flooding the world’s major coastal cities.
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  Some recent studies, though, have proposed estimates below four degrees, stirring climate change skeptics and making some wonder if the future might look better than expected. But the well-regarded climate scientist James Annan warns against dismissing the threat of global warming. Gillis concludes:
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   Even if climate sensitivity turns out to be on the low end of the range, total emissions may wind up being so excessive as to drive the earth toward dangerous temperature increases.
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   So if the recent science stands up to critical examination, it could indeed turn into a ray of hope — but only if it is then followed by a broad new push to get the combustion of fossil fuels under control.
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  Alternatively, we might be able to put excessive carbon dioxide
  <a href="http://www.pbs.org/wgbh/nova/tech/carbon-sink.html" title="into storage.">
   into storage
  </a>
  .
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Electric Shocks to Brain Could Improve Math Skills

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  Oxford University researchers found that students were better number-crunchers after a five-day course of brain stimulation. Here’s Ian Sample writing for Guardian Science:
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<p>
   If future studies prove that it works – and is safe – the cheap and non-invasive procedure might be used routinely to boost the cognitive power of those who fall behind in maths, the scientists said. Researchers led by Roi Cohen Kadosh zapped students’ brains with a technique called transcranial random noise stimulation (TRNS) while they performed simple calculations, or tried to remember mathematical facts by rote learning.
  </p>
<p>
   In the study published in
   <a href="http://dx.doi.org/10.1016/j.cub.2013.04.045" title="">
    Current Biology
   </a>
   , 25 students had electrical pulses fired across their brains, while 26 others had a sham treatment, in which they thought they had brain stimulation, but the equipment was turned off.
  </p>
<p>
   In tests afterwards, the students who had their brains stimulated solved maths puzzles 27% faster than the control group, suggesting that their brains were working more efficiently.
  </p>
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<p>
  Some scientists doubt the claim’s validity, primarily because the study’s sample size was so small. Widespread implementation of this practice could also have ethical ramifications. Listen to this NOVA
  <a href="http://www.pbs.org/wgbh/nova/body/boost-kids-brainpower.html" title="radio story">
   radio story
  </a>
  (co-produced with PRI’s The World) to learn more.
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How to Grow a Green Roof

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  Green rooftops aren’t just verdant escapes for urban dwellers. For the past two years, New York City
  <a href="http://www.nyc.gov/html/planyc2030/html/home/home.shtml" target="_blank">
   Mayor Michael Bloomberg’s PlaNYC initiative
  </a>
  has offered tax abatements for green roof construction projects, which help stabilize building temperatures and manage stormwater runoff. Many of these rooftops are populated with sedum, a plant that’s resilient to wind and UV rays, but, unfortunately, can sometimes make buildings hotter by absorbing heat rather than reflecting it. So what’s a good alternative? The answer might lie in the soil—not the plants themselves. Here’s Amy Kraft writing for Scientific American:
 </p>
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<p>
   Krista McGuire has taken sedum’s inadequacy as a challenge. The assistant professor of biological sciences at Barnard College wanted to see if a variety of native plants could survive on green roofs and how well they would deliver the desired benefits. Since 2010, the year Bloomberg announced his green roof initiative, McGuire has been comparing soil samples from 10 roofs planted with native vegetation with soil from five city parks spanning New York’s five boroughs, seeking to identify the microbial communities that thrive on green roofs to better to understand how healthy rooftop ecosystems sustain themselves.
  </p>
<p>
   Her study,
   <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0058020" target="_blank">
    published in
    <em>
     PLoS ONE
    </em>
</a>
   last April,
   <strong>
</strong>
   found that green roofs have distinct fungal communities that help plants to thrive in harsh, polluted environments and filter heavy metals. On average, 109 different types of fungi were present on each roof including
   <em>
    Pseudallescheria fimeti
   </em>
   , a fungus that grows in polluted soils and human-dominated environments. Rooftop soil also contained fungi from the genus
   <em>
    Peyronellaea,
   </em>
   which live in the tissues of plants to help them take in nutrients.
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<p>
  Her study might be a step in right direction:
 </p>
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<p>
   “In the long term, this information may help individuals decide which types of soil microbes to amend on their green roofs, so that they can maximize plant survival and minimize management,” she says.
  </p>
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<p>
  This discovery is a variation on
  <a href="http://www.pbs.org/wgbh/nova/next/nature/fungal-network-helps-plants-communicate/" title="last week's">
   last week’s
  </a>
  ; a study published in Ecology Letters found that subterranean fungal networks help plants warn each other against impending aphid attacks.
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How to Make a False Memory

<p></p><p><i>“Remembrance of things past is not necessarily the remembrance of things as they were.”</i> —Marcel Proust</p><p>Proust was on to something. As powerful as our memories may be, they’re certainly not infallible. Our minds lead us astray all the time, but experts hadn’t gotten to the root of the brain’s deceptiveness—until now.</p><p>Scientists at the Massachusetts Institute of Technology say they have successfully implanted a false memory in a mouse, giving insight into how memories—true and false—may form in the human brain. Led by Susumu Tonegawa (a Nobel laureate for his work in immunology), the team <a href="http://www.sciencemag.org/">reported Thursday in the journal Science</a> that they caused genetically modified mice to remember being shocked in a particular place when, in reality, that electric shock was delivered when the mouse was somewhere else entirely. Here’s <a href="http://www.technologyreview.com/news/517226/scientists-make-mice-remember-things-that-didnt-happen/">Susan Young, writing</a> for Technology Review:</p><p>Previously, the MIT-based team had <a href="http://www.ncbi.nlm.nih.gov/pubmed/22441246">shown</a> that it could pinpoint the location and assemblage of cells that carry a memory, and that activating those cells stimulated memory recall in mice. To create the new, false memory, Tonegawa’s team reactivated a mouse’s memory of a safe place while the animal received shocks in its feet, thus transforming the original memory.</p><p>First, the team used genetic tricks to label the brain cells involved in the memory of a chamber that was safe and neutral. The next day, they put the animal in a second chamber, a completely different setting. There, the animal got foot shocks while the researchers simultaneously shone light to reactivate the memory of the harmless first chamber. When the animal was put back in the first chamber, it fearfully froze—a clear indication that it remembered getting shocked in that chamber, even though that never happened.</p><p><a href="http://www.nytimes.com/2013/07/26/science/false-memory-planted-in-a-mouse-brain-study-shows.html">James Gorman wrote in The New York Times</a> that although mice and people are evolutionarily distant, the processes that govern memory formation in mammals are ancient. In both mice and men, memories form in an area of the hippocampus called the dentate gyrus—so conclusions drawn from this study are likely to apply to humans as well. Moreover, the scientists’ ability to locate and edit a memory is a significant achievement. Gorman quotes <a href="http://www.nytimes.com/2013/04/30/science/may-britt-and-edvard-moser-explore-the-brains-gps.html?pagewanted=all">Edvard I. Moser</a> , a neuroscientist at the Norwegian University of Science and Technology:</p><p>“What I find fascinating about this,” Dr. Moser said, “is that you actually can point to a physical substrate to memory,” what the researchers call an engram. Neuroscientists have long talked about engrams, but Dr. Moser said the recent research is the closest they have gotten to pointing to a spot in the brain and saying, “That is the memory.”</p><p>Of course, researchers have long known that memory blurs fact and fiction. But this new discovery is an important step toward figuring out how that actually works. <a href="http://www.guardian.co.uk/science/2013/jul/25/false-memory-implanted-mouse-brain">Writes Alok Jha</a> for <i>The Guardian</i> :</p><p>The mouse models created by the MIT team will help scientists ask ever more complex questions about memories in people. “Now that we can reactivate and change the contents of memories in the brain, we can begin asking questions that were once the realm of philosophy,” said Steve Ramirez, a colleague of Tonagawa’s at MIT.</p>

Allison Eck

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