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<p>
  Schrödinger’s cat is famous in the physics world. It’s a curious thought experiment dreamt up by Erwin Schrödinger in which a cat is enclosed in a box with a vial of poison. Until someone opens the box, the cat is both dead
  <em>
   and
  </em>
  alive—we have no way of knowing which until we observe it. The analogy illustrates the principle of quantum superposition: any subatomic particle inhabits all of its possible quantum states (the set of numbers determining the particle’s characteristics) at once—until we measure it.
 </p>
<p>
  Superposition is a feature of the microscopic world—not the macroscopic. But how big is too big before Schrödinger’s cat ceases to be relevant? For example, can we quantum superimpose a real-life cat? Here’s Edwin Cartlidge, writing for Physics World:
 </p>
<blockquote>
<p>
   In recent years physicists have been placing ever-larger objects into states of quantum superposition – the curious state that Schrödinger’s cat finds itself in. Now, researchers in Germany have devised a way of quantifying just how macroscopic those objects are and how much ground still needs to be made up before cats and other familiar items can be held in two or more quantum states at the same time.
  </p>
</blockquote>
<p>
  There are some obstacles to macroscopic superposition. But even if scientists could overcome them, Schrödinger’s cat, if it were real, might just be too fat. Researcher Stefan Nimmrichter noted:
 </p>
<blockquote>
<p>
   “One should never say never, but we will probably never be able to put a cat in a quantum superposition.”
  </p>
</blockquote>
<p>
  Experiments like these could help them find out whether or not a boundary exists—and if it does, where—between the quantum and classical worlds.
 </p>
</section>
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How Fat is Schrödinger’s Cat?





  
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<p>
  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.
 </p>
<blockquote>
<p itemprop="articleBody">
   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.
  </p>
<p itemprop="articleBody">
   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.
  </p>
</blockquote>
<p itemprop="articleBody">
  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:
 </p>
<blockquote>
<p itemprop="articleBody">
   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.
  </p>
<p itemprop="articleBody">
   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.
  </p>
</blockquote>
<p itemprop="articleBody">
  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>
  .
 </p>
</section>
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Scientists Take Global Warming's Temperature





  
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 The skies above Earth are constantly crackling with electric activity, from aurorae that materialize at the poles to sprites that burst upwards from thunderclouds. For the most part, we know how these phenomena work. But another mysterious light source has puzzled scientists for centuries. It doesn’t appear when clouds clash or solar rays pelt the atmosphere, but when the ground rumbles underneath our feet.
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 During some earthquakes, people have reported glowing lights that happen just before or during the shaking. Scientists weren’t certain the phenomenon was real, let alone explainable. But now they might have an answer. In a new study published in
 <i>
  Seismological Research Letters
 </i>
 , scientists from Quebec’s Ministry of Natural Resources and NASA propose that grinding rock can cause stress in deep in the crust, which in some types of rock can break apart pairs of negatively-charged oxygen atoms.
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      <div class="rich-text"><p>
 Joseph Stromberg,
 <a href="http://blogs.smithsonianmag.com/science/2014/01/why-do-lights-sometimes-appear-in-the-sky-during-an-earthquake/">
  writing
 </a>
 for Smithsonian:
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 When this happens, each of the oxygen ions are released, and these can flow through cracks in the rock, towards the surface. At that point, the thinking goes, high-density groups of these charged atoms will ionize pockets of air, forming a charged gas (a plasma) that emits light.
</p>
<p>
 The study’s lead author, geologist Robert Thériault, says this behavior typically happens around the steep vertical faults common in rift zones. He and his team studied 65 historical earthquakes and noted how many reports of glows they could find.
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      <div class="rich-text"><p>
 Alexandra Witze,
 <a href="http://www.nature.com/news/earthquake-lights-linked-to-rift-zones-1.14455">
  writing
 </a>
 for Nature:
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<blockquote>
    <div class="rich-text"><p>
 Thériault’s team decided to compile all the reliable reports they could find, from the year 1600 to today. They focused on 27 earthquakes from the Americas and 38 from Europe, and sorted through many bizarre tales. Off the Peruvian coast in August 2007, a fisherman reported the sky turning violet a few minutes before the sea began shaking. Near Ebingen, Germany, in November 1911, a woman reported seeing glows that moved along the ground “like snakes” as a quake began.
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 The number of reported occurrences is relatively low, making further study challenging. Still, scientists hope to test alternative theories as to how earthquake lights form. For one, they plan to measure soil’s electrical conductivity immediately before or during a quake, to see if that plays a role. No matter what their explanation, though, appearance of the lights may lead to an early warning system for earthquakes.
</p>
<p>
 For more on another type of mysterious electrical phenomenon, watch “At the Edge of Space.”
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 Image Credit:
 <a href="http://www.flickr.com/photos/32360435@N02/3422584440/sizes/o/">
  leandrodemori/Flickr (CC BY-NC-SA 2.0)
 </a>
</p></div>
  



<p>Scientists have proposed that grinding rock creates stress deep in the Earth&#x27;s crust which causes mysterious &quot;earthquake lights.&quot;</p>

What Causes Eerie Earthquake Lights?





  
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 Failed experiments sometimes render
 <a href="http://www.pbs.org/wgbh/nova/physics/blog/2013/06/brilliant-blunders/">
  unexpected results
 </a>
 , and new ideas are born from seemingly banal data.
</p>
<p>
 Even major undertakings, like NASA’s Kepler mission, propel scientists in unintended directions. In December, the
 <a href="http://www.cfa.harvard.edu/HEK/">
  Hunt for Exomoons with Kepler (HEK) project
 </a>
 —which inspects Kepler’s data in search of distant moons—inadvertently discovered the lightest exoplanet yet.
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 The Kepler spacecraft pinpoints exoplanets by looking for transits—the period during which an exoplanet appears to move across the face of its host star, dimming the star’s light. When an exoplanet’s moons are aligned in front of or behind the planet (relative to the host star), the transit looks the same. But when these exomoons are either ahead of or behind the planet’s orbit, they block more light from the sun and exert more gravitational pull on the planet, altering the transit’s duration.
</p>
<p>
 In a new paper, HEK astronomers explain that they found abnormal gravitational tugging in two of the eight systems tested, leading them to believe that there were exomoons in those systems. Unfortunately, their data wasn’t convincing enough, since each of the two systems had two planets in them, raising the possibility that other gravitational interactions caused this effect.
</p>
<p>
 In doing all this work, though, the team wound up calculating the weight of these four exoplanets. One, KOI 314c, was startlingly light.
</p>
<p>
 John Timmer, writing for Ars Technica:
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 […] KOI 314c was only slightly more dense than liquid water: 1.31 grams per cubic centimeter. For context, the Earth’s density is 5.52 grams per cubic centimeter. Combined with its relatively small size, that makes KOI 314c the lightest planet we’ve ever discovered.
</p>
<p>
 Although it’s technically possible that the planet is little more than a giant ball of water, the HEK team favors an alternate explanation: it’s an evaporating Neptune. The planet’s density suggests that it has an atmosphere that’s mostly hydrogen and helium, but a very thick one: approximately 17 percent of the planet’s radius. However, the object’s gravity would probably have trouble hanging on to that gas given how close it orbits to its host star every 23 days. The researchers argue that it started its existence as something closer to Neptune, but it has bled off some of its atmosphere since.
</p></div>
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 Even though the finding calls into question the basic definition of a planet, which is itself nebulous, it underscores the importance of the Kepler mission in uncovering new insights about our universe.
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 Image Credit:
 <a href="http://www.cfa.harvard.edu/HEK/koi314.html">
  European Southern Observatory
 </a>
</p></div>
  



<p>The Hunt for Exomoons with Kepler project inadvertently discovered the lightest exoplanet yet while evaluating the duration of exoplanet transits.</p>

That's No Exomoon, It's an Evaporating Planet





  
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<p>
 Biomimicry—the use of nature to inspire design—is
 <a href="http://mentalfloss.com/article/22702/10-technologies-we-stole-animal-kingdom">
  widely used by cutting-edge technologists
 </a>
 to design everything from bullet train noses, new X-ray machines, and lighter and safer cars. But let’s take a moment to flip that idea on its head. Are there things we thought humans invented that have been later discovered in nature?
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 As a matter of fact, yes. Nymphs of a common insect found in Britain—
 <i>
  Issus coeleoptratus
 </i>
 , a species of planthopper—has what were presumably a very human creation—gears. While working at the University of Cambridge, Greg Sutton noticed a strange mechanism on the insect’s back legs. Here’s Adam Cole
 <a href="http://www.npr.org/2013/09/13/219739500/living-gears-help-this-bug-jump">
  reporting
 </a>
 for NPR’s Morning Edition:
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 There was a tiny row of bumps on the inside of each leg where it met the insect’s body. The bumps looked just like the teeth of gears. And when the planthopper jumped, they acted like gears too — as teeth meshed, the legs turned in synchrony. Sutton says his finding,
 <a href="http://www.sciencemag.org/content/341/6151/1254">
  published
 </a>
 this week in
 <i>
  Science
 </i>
 , is the first mechanical gear system ever observed in nature.
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 The small bumps—called trochanters—are incredibly well suited to the planthopper, which springs away from danger in the blink of an eye. Sutton filmed the bugs hopping with a high-speed camera and noticed that both leaping legs moved almost simultaneously—the difference between the two was as short as 30 millionths of a second. That’s much shorter than the time it takes for a neuron to execute even the smallest, most rudimentary task. The synchrony propels the insect faster, farther, and straighter.
</p>
<p>
 Ed Yong,
 <a href="http://phenomena.nationalgeographic.com/2013/09/12/this-insect-has-gears-in-its-legs/">
  writing
 </a>
 for Not Exactly Rocket Science, has more background on Sutton’s research:
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 The planthopper nymphs lose them when they become adults. But the adults don’t shoot off in uncoordinated spins—if anything, they’re better jumpers than the youngsters. Their hind trochanters make much closer contact with each other, and Sutton thinks that
 <a href="http://www.ncbi.nlm.nih.gov/pubmed/20086132">
  the friction between them helps to keep them in time
 </a>
 . “We’re kind of sure about that, but not entirely sure,” he says.
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      <div class="rich-text"><p>
 <i>
  Issus coeleoptratus
 </i>
 ‘s gears work similarly to their human-designed counterparts, but they have a leg up at smaller scales. Sutton—a mechanical engineer—thinks the trochanters could help us build more efficient machines:
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 Modern machines, such as 3-D printers, could easily create gears with these shark-fin teeth. Sutton is really excited by the prospect, and suspects that they may perform better in very small machines. “Modern machinery often doesn’t work at very small scales,” he says. “Friction doesn’t matter so much when you have two big gears next to each other but when you get small, friction starts killing you.”
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 The planthoppers might help to solve that problem. “We’re still being impressed and shocked by what we find in the back garden,” says Sutton.
</p>
<p>
 <i>
  For more bioinspired technologies, watch “Making Stuff Wilder”, airing October 23 at 9/8 central on PBS.
 </i>
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 Photo by Burrows/Sutton
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<p>Are there things we thought humans invented that have been later discovered in nature?</p>

This Insect Jumps Using Built-In Gears





  
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 <p>
  Surgery is a risky and brutal business. Even today’s most advanced medical technology—surgical robots—involves the touch of cold, unyielding metal to soft, delicate flesh. With all of those complications, surgery today can still be a precarious procedure. But soft robots
  <a href="http://www.gizmag.com/camouflage-robot-harvard/23749/" title="first created">
   first created
  </a>
  by Harvard University scientists might provide some relief.
 </p>
 <p>
  The robots’ ability to maneuver through small spaces and
  <a href="http://www.youtube.com/watch?v=LpOl_pEmRqs" title="camouflage themselves">
   camouflage themselves
  </a>
  like
  <a href="http://www.pbs.org/wgbh/nova/nature/kings-of-camouflage.html" title="cuttlefish">
   cuttlefish
  </a>
  do initially caught the attention of the military. But now these squishy creations are being re-imagined as biomedical tools. Here’s Larry Greenemeier writing for Scientific American:
 </p>
 <blockquote>
  <p>
   Hard robots require a sophisticated feedback mechanism to help them determine how much force to apply during surgery so they do not damage our delicate tissues and organs. Soft robots could take advantage of their rubbery appendages to reduce the likelihood of surgical damage, says Carl Vause, CEO of Soft Robotics. “Specifically, with medical devices, [you would be] allowing a robotic instrument to get into a small space, be reconfigurable in that space and do it in a way that’s tissue compliant.” Another advantage: Soft robots can be 3-D printed in a day or two from silicone and other materials that cost about $20.
  </p>
 </blockquote>
 
            <figure class="richtext-image full-width"><img alt="soft-robot" class="richtext-image full-width" height="450" width="800"
            src="/wgbh/nova/media/images/soft-robot.width-800.jpg"/><figcaption>
  This glowing robot might also be the surgical tool of the future.
 <div class="credit"></div></figcaption>
            </figure>
            
 <p>
  Robotic surgery has prompted
  <a href="http://well.blogs.nytimes.com/2013/09/09/new-concerns-on-robotic-surgeries/" title="some concern">
   some concern
  </a>
  in the recent past. The most well-known robot surgical system, known as da Vinci, is a $2 million endeavor that allows surgeons to manipulate laparoscopic instruments and an endoscopic camera attached to four robotic arms. But da Vinci significantly ups the cost of surgery and has also led to several lawsuits due to reports of sepsis, punctured blood vessels, and more.
 </p>
 <blockquote>
  <p>
   It will be some time before soft robots are capable of anything nearly as sophisticated as da Vinci, but there is a lot of interest in how this emerging technology could be used in the medical field—either on its own or combined with a surgical system like da Vinci.
  </p>
 </blockquote>
 <p>
  Experts are also interested in how soft robots could aid in prosthetics. Discover how scientists and engineers are
  <a href="http://www.pbs.org/wgbh/nova/next/tech/prospects-for-prostheses/">
   adding intelligence and flexibility into advanced prostheses
  </a>
  .
 </p>
 <p>
  To learn more about one of the critters that inspired soft robots, watch “Kings of Camouflage” below and tune in to NOVA’s “
  <a href="http://www.pbs.org/wgbh/nova/tech/making-more-stuff.html#making-stuff-wilder" title="Making Stuff: Wilder">
   Making Stuff: Wilder
  </a>
  ,” airing October 23 at 9/8c on PBS.
 </p>
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 Photo courtesy
 <a href="http://www.darpa.mil/NewsEvents/Releases/2012/08/16a.aspx">
  DARPA
 </a>
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3D Printed Soft Robots Could Ease Pain of Surgery





  
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<p>
  NASA’s
  <em>
   Cassini
  </em>
  spacecraft—in orbit around Saturn—took a picture of Earth last Friday, July 19, from nearly 900 million miles away. The entire image, which will take several weeks to develop, will depict more than just our planet (a “
  <a href="http://www.youtube.com/watch?v=p86BPM1GV8M" title='"pale blue dot"'>
   pale blue dot
  </a>
  ,” a fraction of a pixel, compared to everything else). For now, we have a portion of it. It took approximately 1 hour, 20 minutes and 24 seconds for the photons that went into this image to reach
  <em>
   Cassini’
  </em>
  s wide-angle lens.
 </p>

            <figure class="richtext-image full-width"><img alt="Earth-Moon System from Cassini" class="richtext-image full-width" height="450" width="800"
            src="/wgbh/nova/media/images/earthmoon_cassini_960_v2.width-800.jpg"/><figcaption><div class="credit"></div></figcaption>
            </figure>
            

<p>
  Here’s Lee Billings, writing for Scientific American before the photo shoot:
 </p>
<blockquote>
<p>
   Built, launched and operated at a total cost of more than $3 billion, Cassini will spend 15 minutes capturing a natural-color photographic mosaic of Saturn’s “E” ring, an annulus of dust and water ice fed by plumes of vapor venting from somewhere warm, wet, and potentially habitable deep within the icy moon
   <a href="http://www.scientificamerican.com/article.cfm?id=enceladus-secrets">
    Enceladus
   </a>
   . Another attraction will lurk in the far distance, barely visible just outside the E ring by virtue of Saturn’s deep shadow: The blue crescent of the sunlit Earth, bearing an untold number of upturned gazes from potential fans in the continental United States, the Caribbean, Central America, or the eastern half of the South Pacific. With a bit of luck, Cassini might also glimpse Earth’s adjacent Moon.
  </p>
</blockquote>
<p>
  Carolyn Porco, leader of
  <em>
   Cassini
  </em>
  ’s imaging team, says this is likely the last time the satellite will observe the Earth. In 2017, the craft will reach the end of its life and will descend into Saturn’s atmosphere; until then, researchers are hoping to make the most of its flight.
 </p>
<blockquote>
<p>
   “It’s not clear when we’ll ever do this again,” Porco says. “Missions this big and ambitious aren’t really in vogue anymore, so maybe we’ll only have a spacecraft this sophisticated out there once every hundred years. I do see this as probably our last great, gorgeous look back at Saturn and at the Earth before Cassini goes dark.”
  </p>
</blockquote>
<p>
  Space enthusiasts across the globe waved at Saturn on Friday. Take a look at
  <a href="http://storify.com/VeronicaMcG/wave-at-saturn" title="this NASA Storify">
   NASA’s collection
  </a>
  of photos from people who joined in.
 </p>
</section>
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Allison Eck