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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>

  



How Fat is Schrödinger’s Cat?





  
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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="https://www.pbs.org/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>

  



Cassini Captures Earth From Afar





  
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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>

  



Scientists Take Global Warming's Temperature





  
      <p>
 Chemtrails. HAARP. The Illuminati. Conspiracy theories are abound on the Internet, but they only prove one thing: that in a virtual world, people make themselves vulnerable to sketchy claims and spotty tales.
</p>
<p>
 Conspiracy-tainted remarks are littered throughout social media networks like Facebook. Walter Quattrociocchi of Northeastern University wanted to better understand how they spread, so he and his colleagues
 <a href="http://arxiv.org/abs/1403.3344">
  studied
 </a>
 the way people interact with Facebook posts that include content known to be either sound or suspect.
</p>
  

  
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      <p>
 MIT Technology Review:
</p>
  

  
      

<blockquote>
    <p>
 [Quattrociocchi and his colleagues] studied how over 1 million people treated political information posted on Facebook during the Italian elections in 2013. In particular, they looked at how these people ‘liked’ posts and commented on them from mainstream news organisations, from alternative news organisation and from pages devoted political commentary.
</p>
<p>
 They then studied how the same people reacted to false news injected into common circulation by “trolls” on pages known to produce satirical news content or otherwise false statements.
</p>
</blockquote>

  

  
      <p>
 The results suggest that conspiracy theories may arise from posts made by users trolling the page, which are supposed to parody the target group. Eventually, though, “troll memes fomented animated debates and diffused through the community as any other information would,” Quattrociocchi and colleagues write.
</p>
<p>
 The team also learned that people discuss ideas on Facebook for the same length of time across the board—no matter what kind of page they post to. They also found that people who are attracted to alternative news sites are more likely to feed into and perpetuate false claims.
</p>
<p>
 It’s a somewhat ironic result, since some people who gravitate toward alternative sites do so to
 <i>
  avoid
 </i>
 what they call the “mass manipulation” that they think occurs on more mainstream pages.
</p>
  

  
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      <p>
 Photo Credit:
 <a href="http://www.flickr.com/photos/andrea-ursini-casalena/2928083995/">
  Andrea Ursini Casalena / Flickr (CC BY-NC-SA 2.0)
 </a>
</p>
  



"Chemtrails" are a common conspiracy theory on Facebook.

<p>A new study shows how certain people, based the type of media they consume, make themselves vulnerable to conspiracy theories on social media.</p>

How Conspiracy Theories Emerge on Facebook





  
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 <p>
  Over ten years ago, Jef Boeke embarked on a research project to understand what might be the most important microorganism to human civilization,
  <i>
   Saccharomyces cerevisiae
  </i>
  , also known as baker’s yeast or brewer’s yeast. For millennia, we’ve used yeast for feasts and festivities, but we didn’t really know how it worked. Even today, the critter remains something of an enigma. Boeke, who is a professor at Johns Hopkins University, wanted to make one, from scratch. Well, at least its genome.
 </p>
 <p>
  The project, dubbed Synthetic Yeast 2.0, was excruciatingly slow-going at first. So Boeke and his team decided to abort the mission in favor of a simpler approach centered on yeast chromosome number 3, which contains the code to the fungus’s sexual behavior. Through a course at Johns Hopkins called “Build a Genome,” Boeke and his colleagues enlisted the help of undergrads, who collectively synthesized the regions of the chromosome that code for proteins, the compounds that perform actions with a cell. At 272,871 base pairs long, this “abridged” version represents only 2.5 percent of the entire yeast genome.
 </p>
 
            <figure class="richtext-image full-width"><img alt="bread-basket" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/bread-basket.width-800.jpg"/><figcaption>
  Yeast gives rise—literally—to bread. To understand how, scientists are turning to synthetic biology.
 <div class="credit"></div></figcaption>
            </figure>
            
 <p>
  Why would scientists chop away at DNA like this? Over the course of yeast’s evolution, it acquired extra sequencing—accessories, if you will—that optimize its ability to function but aren’t essential to its survival. One way of getting clarity on how an organism works is to eliminate these extra variables and structure your prototype around the genetic information you can control: the stuff that actually
  <i>
   makes
  </i>
  proteins. It’s like a minimum viable chromosome, giving scientists access to the spine of the genetic skeleton.
 </p>
 <p>
  Ewen Callaway
  <a href="http://www.nature.com/news/first-synthetic-yeast-chromosome-revealed-1.14941">
   reporting
  </a>
  for Nature, describes how the project worked:
 </p>
 <blockquote>
  <p>
   Each student makes their own stretch of the yeast genome, which involves stitching together very short lengths of DNA created by a DNA-synthesis machine into ever-larger chunks. These chunks are then incorporated into the yeast chromosome, a few at a time, through a process called homologous recombination. Eventually, this results in an entirely synthetic chromosome. Many of the students are co-authors on Boeke’s
   <i>
    Science
   </i>
   <a href="http://www.nature.com/news/first-synthetic-yeast-chromosome-revealed-1.14941#b1">
    paper
   </a>
   , which details the synthesis of
   <i>
    S. cerevisiae
   </i>
   ‘s chromosome III.
  </p>
 </blockquote>
 <p>
  The Synthetic Yeast 2.0 project isn’t the first to replicate a major portion of an organism’s genome—that honor went to researchers at the J. Craig Venter Institute who synthesized the genome of
  <i>
   Mycoplasma mycoides
  </i>
  , a relatively simple bacterium. But it is the first time we’ve been able to do it with a chromosome. David Biello
  <a href="http://www.scientificamerican.com/article/bakers-yeast-gets-a-genetic-makeover/">
   reporting
  </a>
  for Scientific American, has more:
 </p>
 <blockquote>
  <p>
   This marks the first time scientists have synthesized the genetics of a complex organism, a landmark achievement in the field of synthetic biology, and given the college kids involved, a triumph for the new movement known as “DIY biology.” Prior specialist work had succeeded in synthesizing the entire genetic code of simpler microbes, such as the goat pathogen
   <i>
    Mycoplasma mycoides
   </i>
   , renamed JCVI-syn1.0 by its creators, which has been lying dormant in a freezer since 2010.
  </p>
 </blockquote>
 <p>
  The synthetic
  <i>
   Mycoplasma mycoides
  </i>
  genome was nearly identical to the original. The synthetic chromosome in yeast isn’t. By excluding the noncoding regions, Boeke hopes to create an experimental platform that will allow researchers to test the function of various genes in a highly controlled fashion. It’s the sort of undertaking that could allow us to finally get a handle on what, exactly, yeast does to turn malt and hops into beer or flour and water into bread.
 </p>
</section>

  

  
      <p>
 Photo Credit:
 <a href="http://www.flickr.com/photos/djwtwo/6296745779/">
  Dennis Wilkinson / Flickr (CC BY-NC-SA 2.0)
 </a>
</p>
  



College Students Create Groundbreaking Synthetic Yeast Chromosome





  
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 <p>
  A stick-on temporary tattoo in the form of a mini computer could be the next medical marvel, with the power to monitor muscle activity and deliver personalized therapy.
 </p>
 <p>
  While researchers have created such a wearable device, they’ll encounter a few more challenges before it can be used in clinics and hospitals. But it’s still a major step that could enable a rich new source of data for biomedical researchers. Here’s Jessica Morrison,
  <a href="http://www.nature.com/news/electronic-skin-equipped-with-memory-1.14952">
   reporting
  </a>
  for Nature:
 </p>
 <blockquote>
  <p>
   Similar efforts to develop ‘electronic skin’ abound, but the device is the first that can store information and also deliver medicine — combining patient treatment and monitoring. Its creators, who
   <a href="http://www.nature.com/news/electronic-skin-equipped-with-memory-1.14952">
    report
   </a>
   their findings today in
   <i>
    Nature Nanotechnology
   </i>
   , say that the technology could one day aid patients with movement disorders such as Parkinson’s disease or epilepsy.
  </p>
 </blockquote>
 
            <figure class="richtext-image full-width"><img alt="electronic_skin_orange_web" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/electronic_skin_orange_web.width-800.jpg"/><figcaption>
  This wearable "electronic skin" is the first to be equipped with memory as well as the ability to inject drugs based on the information it receives.
 <div class="credit"></div></figcaption>
            </figure>
            
 <blockquote>
  <p>
   The researchers constructed the device by layering a package of stretchable nanomaterials—sensors that detect temperature and motion, resistive RAM for data storage, microheaters and drugs—onto a material that mimics the softness and flexibility of the skin. The result was a sticky patch containing a device roughly 4 centimetres long, 2 cm wide and 0.003 millimetres thick, says study co-author Nanshu Lu, a mechanical engineer at the University of Texas in Austin.
  </p>
 </blockquote>
 <p>
  In November, Kim Tingley
  <a href="http://www.newyorker.com/reporting/2013/11/25/131125fa_fact_tingley">
   wrote
  </a>
  for The New Yorker on the assent of cyborg skin, and the barriers that stand in the way of scientists’ ability to sync our electric bodies with our electronic devices. In writing about the first “electronic skin” breakthrough in 2011, Tingley notes:
 </p>
 <blockquote>
  <p>
   The problem is physical: the body is soft, supple, and curved, but modern electronics, built on silicon computer chips, are rigid and flat, likely to shatter if dropped on a sidewalk. John Rogers, a shy-eyed materials scientist at the University of Illinois at Urbana-Champaign, likes to point out that, in 3.5 billion years, evolution has solved countless challenging problems without creating something that looks like a silicon chip. “You think about the natural world, there’s a lot of rough and tumble,” he told me. “You have environments that are a lot less well-controlled than an iPhone case.” Researchers traditionally considered marrying electronics to biology using circuits made not from inorganic silicon but from pliable organic materials—the carbon-based building blocks of life. But current flows through these materials too slowly to power computers and gadgets.
  </p>
 </blockquote>
 <p>
  Rogers and his team solved that problem by making their patch out of a stretchy lattice of sensors sandwiched between two protective layers—which in turn, sit on a sheet of polyester designed to imitate skin’s physical properties. It could record heartbeats, brain activity, and muscle contractions; the only problem was that the patch fell off after a few days. Lu’s and her colleagues’ device, though, is meant for continuous, long-term data storage—a first in the industry. It can also deliver drugs in response to the bodily information it receives.
 </p>
 <p>
  Unfortunately, the device works only when connected to a power supply and a data transmitter. These materials would need to be nearly as soft as the “tattoo” itself. And even then, there would be other kinks to work out. But scientists have high hopes that the devices could liberate hospitals and clinics from the clunky straps and pads that currently help monitor patients’ well-being.
 </p>
</section>

  

  
      <p>
 Photo Credit: Donghee Son and Jongha Lee
</p>
  



Peelable 'Electronic Skin' Could Someday Store Bodily Data and Inject Medicine





  
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 <p>
  Move over, Mars. In the search for extraterrestrial life, moons are now in the limelight.
 </p>
 <p>
  Enceladus—one of the Ringed Planet’s icy and austere orbiters has been on astronomers’ shortlist of potential hosts of alien life, especially since they discovered
  <a href="http://www.nytimes.com/2006/03/10/science/space/10saturn.html">
   geysers of ice crystals shooting out of its south pole
  </a>
  in 2005. They hypothesized that a deep ocean the size of Lake Superior sits underneath its highly tectonic and veiny surface, potentially feeding those gushers.
 </p>
 <p>
  Normally, liquid water couldn’t exist that far out in the solar system, but the gravitational pull of Enceladus’s neighbor, Dione, bends the icy moon’s outer layer, creating heat through friction. NASA’s
  <i>
   Cassini
  </i>
  spacecraft has repeatedly flown by the surface of Enceladus to better understand the temperature dynamics that create these explosive geysers.
 </p>
 
            <figure class="richtext-image full-width"><img alt="saturn-water" class="richtext-image full-width" height="450" width="800"
            src="https://www.pbs.org/wgbh/nova/media/images/saturn-water.width-800.jpg"/><figcaption>
  Below the austere and veiny surface of Enceladus is an ocean up to six miles deep.
 <div class="credit"></div></figcaption>
            </figure>
            
 <p>
  Kenneth Chang,
  <a href="http://www.nytimes.com/2014/04/04/science/space/a-moon-of-saturn-has-a-sea-scientists-say.html">
   writing
  </a>
  for The New York Times:
 </p>
 <blockquote>
  <p>
   Cassini has no instruments that can directly detect water beneath the surface, but three flybys in the years 2010-12 were devoted to producing a map of the gravity field, noting where the pull was stronger or weaker. During the flybys, lasting just a few minutes, radio telescopes that are part of NASA’s Deep Space Network broadcast a signal to the spacecraft, which echoed it back to Earth. As the pull of Enceladus’s gravity sped and then slowed the spacecraft, the frequency of the radio signal shifted, just as the pitch of a train whistle rises and falls as it passes by a listener.
  </p>
  <p>
   Using atomic clocks on Earth, the scientists measured the radio frequency with enough precision that they could discern changes in the velocity of Cassini, hundreds of millions of miles away, as minuscule as 14 inches an hour.
  </p>
 </blockquote>
 <p>
  What they detected was a gravitational asymmetry—the pull of gravity was weaker near the south pole, which made sense because there’s a depression in the planet’s landscape there. But the depression is so large that it should have made the gravity weaker than what they measured, so they knew that something more dense must be making up the difference—something like liquid water, which is denser than ice by 8%. Using that information, they calculated that a sea up to six miles thick probably exists 20 to 25 miles beneath the surface.
 </p>
 <p>
  Perhaps more exciting is that astronomers now have proof of this water coming into contact with Enceladus’ rocky core. Water touching rock may seem prosaic here on Earth, but the union of the two can make for some compelling chemistry, creating conditions that could foster life. Here’s Alexandre Witze,
  <a href="http://www.nature.com/news/icy-enceladus-hides-a-watery-ocean-1.14985">
   writing
  </a>
  for Nature:
 </p>
 <blockquote>
  <p>
   On Earth, for instance, hot water from sea-floor hydrothermal vents interacts with rocks to generate chemical reactions and nutrients that life can feed off. Enceladus may well have similar molecules at the bottom of its ocean, McKay says. Cassini has spotted tiny silica particles in the Enceladus plume, which may be fragments of the rocky core that could carry nutrients.
  </p>
 </blockquote>
 <p>
  What remains to be seen is how long this ocean has been around and whether or not it’s going to keep cooling or stay in its current condition for some time. Regardless, the chemical conditions on Enceladus may be our best hope for finding life in solar system, which has some astronomers proposing sending robots to investigate. Other candidates for such a mission would be Jupiter’s moon Europa or Saturn’s other moon, Titan.
 </p>
 <p>
  Astrobiologists have found icy plumes on Europa, too, but only on occasion. And Titan has liquid methane, which working with other compounds could concoct life, but in a very different way from what we know on Earth. Only Enceladus is known to have the four essential ingredients for Earth-like life: liquid water, energy, carbon, and nitrogen. It’s still a dark, largely unknown territory, but a future mission manages to capture particles from Enceladus’ plumes, it could confirm the existence of life beyond Earth.
 </p>
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 <div class="inline-caption">
  Learn more about the possibility Enceladus holds in "Finding Life Beyond Earth."
 </div>
</section>

  

  
      <p>
 Photo Credit:
 <a>
  NASA/JPL-Caltech and Space Science Institute
 </a>
</p>
  



Allison Eck

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