NOVA’s Nobel Poll: Scientists Predict the 2013 Laureates

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<p>
  The selection process for the Nobel prizes—this year’s to be announced starting October 7—is highly secretive, but that doesn’t stop the speculation. In that spirit, we surveyed dozens of scientists in the fields of physics, chemistry, and physiology, asking who they think could win this year’s Nobel Prize.
 </p>
<h2>
  Physics
 </h2>
<p>
  For the physics prize, almost all of our respondents predicted that it will honor the discovery of the Higgs boson,
  <a href="http://www.pbs.org/wgbh/nova/physics/higgs-boson-revealed.html">
   announced tentatively in July 2012
  </a>
  and with
  <a href="http://www.pbs.org/wgbh/nova/next/physics/higgs-boson-discovered/">
   greater confidence in March 2013
  </a>
  . But with thousands of scientists involved in the discovery,
  <a href="http://www.pbs.org/wgbh/nova/physics/blog/2012/03/a-higgs-by-any-other-name/">
   eight or more
  </a>
  contributing to the origination of the theory, and the prize allowed to go to no more than three winners, how will the Nobel committee divvy up the laurels?
 </p>
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/nobel-medal.width-990_CHpDg2c.jpg"/>
<figcaption>The Nobel Prize medal
        
    </figcaption>
</figure>
<p>
  Most of the physicists responding to our poll felt that the prize would go to Peter Higgs and Francois Englert, who independently invoked a new field—known today as the Higgs field—to explain why subatomic particles have mass. Their ideas were published within just weeks of each other. As Peter G. O. Freund, a theoretical physicist at the University of Chicago, wrote, “For the better part of the past half century the phenomenon discovered by Englert, Brout [Englert’s coauthor] and Higgs has been a crucial ingredient of the standard model of physics, and repeatedly verified indirectly along with this model. Now, after the phenomenon’s beautiful direct verification at the LHC, it is high time to honor its discoverers with the Nobel Prize.”
 </p>
<h2>
  Chemistry
 </h2>
<p>
  The chemists selected David A. Evans, a synthetic organic chemist at Harvard. Evans’s work focuses on both total synthesis and stereoselectivity. Total synthesis involves creating synthetic versions of compounds found in nature. The pharmaceutical industry relies on the field’s techniques heavily, as they allow researchers to mine the natural world for compounds that may prove beneficial as treatments, even if those compounds are incredibly rare. Evans is something of a total synthesis wizard—he and his lab have synthesized over 50 natural products throughout the years.
 </p>
<p>
  Stereoselectivity, Evans’s other speciality, is where one chemical reaction spits out different three-dimensional orientations of the same molecule, or stereoisomers. Specifically, Evans is interested in enantiomers, a specific class of stereoisomer that involves mirror images of the same molecule. Evans has been developing techniques that vary the levels of stereoselectivity in the hopes that someday we’ll be able to completely control the configuration of the final product. Like total synthesis, it’s important in the development and production of pharmaceuticals. The painkiller naproxen is a perfect example. One enantiomer relieves pain, while the other simply causes liver damage. Producing and selecting the right enantiomer is crucial.
 </p>
<h2>
  Medicine
 </h2>
<p>
  For medicine and physiology, unfortunately our poll didn’t garner enough results to say anything conclusive, but one widely-watched Nobel prediction site, ScienceWatch, published by Thomson Reuters, has identified as possible winners A. Paul Alivisatos, Chad A. Mirkin, and Nadrian C. Seeman for their work on DNA nanotechnology, a promising and relatively new field that uses the unique properties of both DNA and nanoparticles to study biological processes and treat the human body. Mirkin’s research, for example,
  <a href="http://www.pbs.org/wgbh/nova/next/tech/nanoparticles-and-the-future-of-medicine/">
   uses gold nanoparticles studded with nucleic acids
  </a>
  to deliver drugs targeted at specific cells.
 </p>
<p>
  It’s important to keep in mind that these predictions are just that, predictions. We’ll have to wait until next week to see if any pan out. But in the meantime, you can
  <a href="http://svy.mk/19mOIwz">
   voice your opinion in our public Nobel poll
  </a>
  and see which scientists the crowd feels are this year’s frontrunners.
 </p>
</section>
<p>
 Photo credit: Public domain
</p>

Welcome to The Nature of Reality

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<p>
  When I was seven, I understood relativity perfectly. I
  <em>
   got
  </em>
  it. At least I thought I did. And it was glorious.
 </p>
<p>
  It all started with
  <em>
<a href="http://en.wikipedia.org/wiki/Flight_of_the_Navigator">
    The Flight of the Navigator
   </a>
</em>
  , that movie about the kid who accidentally stumbles upon a space ship and has a grand old afternoon traversing the galaxy in the company of its cargo of friendly creatures. The problem? When he returns to Earth he finds that eight years have elapsed. He has been declared missing; when he rings the bell at his old house, a stranger answers the door.
 </p>
<p>
<em>
   The Flight of the Navigator
  </em>
  is a story about
  <a href="http://www.pbs.org/wgbh/nova/physics/spacetime-trip.html" target="_blank" title="A Trip Through Spacetime">
   time dilation
  </a>
  . The ship was traveling close to the speed of light, so time passed significantly more slowly for its passengers than it did for those back on Earth. That’s special relativity for you. It seemed easy, elegant, amazing.
 </p>
<p>
  For the next few years, that was my relationship with relativity. Then came the equations, and suddenly relatively didn’t seem so easy any more. Elegant, maybe. But that first spark of intuition got lost in symbols, equations, calculations and miscalculations. So I wondered: Why can’t we have it both ways? Is it possible to be both wide-eyed and rigorous, methodical and amazed?
 </p>
<p>
  That’s a balance even physicists struggle with. As MIT theorist Max Tegmark told NOVA, “When I was in high school, physics was my most boring subject….It was only later that I realized that physics isn’t at all about just solving some equations. It’s about figuring out what reality is all about.”
 </p>
<p>
  That’s what we’re doing on this blog: taking on the biggest questions of all, the ones that get at the very nature of reality. What happens to information inside a black hole? What are we really talking about when we talk about teleportation? What if the laws of physics can’t be unified? Every week, we’ll have a new post from a scientist or science writer–look for James Stein, Sean Carroll, and Frank Wilczek in the coming weeks and months–with plenty of room for you to join the discussion with your own questions and ideas.
 </p>
<p>
  We hope you’ll let us know what subjects in fundamental physics you want to hear about—the stranger, the better. Can neutrinos really go
  <a href="http://www.nature.com/news/2011/110922/full/news.2011.554.html">
   faster than the speed of light
  </a>
  ? What is this
  <a href="http://www.pbs.org/wgbh/nova/physics/spacetime-lemonade.html">
   spacetime
  </a>
  thing anyway? Is our universe just one of countless others in a
  <a href="http://www.pbs.org/wgbh/nova/physics/johnson-multiverse.html">
   multiverse
  </a>
  ? Join us as we dive deep and discover how physics is changing what we thought we knew about the nature of reality.
 </p>
</section>

Live Webcasts: The Latest Higgs Results

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<p>
  Watch this space the week of July 2, 2012 for a series of live webcasts from Fermilab and CERN on the latest results in the search for the
  <a href="http://www.pbs.org/wgbh/nova/blogs/physics/2012/06/the-higgs-boson-explained/">
   Higgs boson
  </a>
  .
 </p>
<p>
<strong>
   Wednesday, July 4: CERN
  </strong>
</p>
<p>
  Come back at 3 am ET on July 4, 2012 for a
  <a href="http://webcast.web.cern.ch/webcast/">
   live webcast from CERN
  </a>
  revealing the latest results in the search for the Higgs boson. A scientific seminar will begin at 3 am ET followed by a press conference at 5 am ET. Stay tuned!
 </p>
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</figure>
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</section>

See scientists announce their latest findings in the ongoing search for the elusive Higgs boson.

Fermilab Rings in Higgs Week

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<p>
  Higgs week is here!
 </p>
<p>
  This week, the search for the
  <a href="http://www.pbs.org/wgbh/nova/blogs/physics/2012/06/the-higgs-boson-explained/">
   Higgs boson
  </a>
  —the elusive subatomic particle that is a critical piece of the Standard Model of physics—may reach its climax when, on Wednesday, two research teams
  <a href="http://webcast.web.cern.ch/webcast/">
   announce the results
  </a>
  of their work at the Large Hadron Collider (LHC) at CERN.
 </p>
<p>
  But before there was the LHC, there was the Tevatron, a particle accelerator at Fermilab. And before the LHC’s big announcement, there was a not-quite-so-big
  <a href="http://www.pbs.org/wgbh/nova/blogs/physics/2012/07/live-webcasts-the-latest-higgs-results/">
   announcement
  </a>
  from the Tevatron teams as they gathered with colleagues this morning to announce the results of the most detailed analysis so far of ten years’-worth of their Higgs search data.
  <br/>
<div class="wp-caption alignnone" id="attachment_774" style="max-width: 510px">
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/11-0226-01d.width-990_s3SrH33.jpg"/>
<figcaption>
</figcaption>
</figure>
<p class="wp-caption-text">
    The Tevatron at Fermilab. Image courtesy of Fermilab.
   </p>
</div>
</p>
<p>
  The Tevatron
  <a href="http://www.pbs.org/wgbh/nova/insidenova/2011/09/hail-and-farewell-grand-colliders.html">
   shut down last year
  </a>
  , passing the baton to the newer, more powerful LHC. But the scientists working on two of the Tevatron’s detectors, CDF and DZero, haven’t given up searching for traces of the Higgs in their own data. Using ever-smarter computer algorithms, they aim to wring as much information as they can out of the data they’ve accumulated. As Wade Fisher, the Michigan State University scientist representing DZero at this morning’s conference, put it: “We’re still working, we’re not stopping….There’s still gas in the tank.”
 </p>
<p>
  What they’ve found so far is suggestive of the Higgs, but doesn’t rise to the level of discovery. Combining data from both CDF and DZero, they’ve
  <a href="http://www.fnal.gov/pub/presspass/press_releases/2012/Higgs-Tevatron-20120702.html">
   eked out a signal
  </a>
  that might be due to the Higgs, but there is also a one-in-550 chance that it is down to random fluctuations.
 </p>
<p>
  To claim a
  <a href="http://www.symmetrymagazine.org/breaking/2012/06/29/what-does-it-take-to-claim-discovery-of-the-higgs/">
   discovery
  </a>
  , the physicists need to whittle that random-chance number down to one in three and a half million—“five sigma,” in stat-speak.
 </p>
<p>
  That’s what the physics world will be holding its breath for on Wednesday, when two LHC collaborations release their results.
 </p>
<p>
  Will they confirm the hints that the Tevatron has seen? Or will these inklings—and our hopes of completing the Standard Model of physics–evaporate into the mist of random fluctuations?
 </p>
<p>
  As Fermilab’s Eric James put it this morning: “We’re likely, after all this time, to find something out one way or the other.”
 </p>
</section>

Bittersweet Victory: Physics After the Higgs

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<p>
  When I see those victorious Olympic athletes all bedecked on the podium, beaming their gold-medal smiles and crying their gold-medal tears, I can’t help thinking:
  <em>
   Now what?
  </em>
</p>
<p>
  And now that the coming-out party for the Higgs (or the Higgs-like boson, if you must) is over—the bubbly popped, the headlines receded—are physicists asking themselves the same question?
 </p>
<p>
  Certainly, physicists are not crying into their champagne. The discovery of a new boson right where the Higgs should be is a scientific tour-de-force. “It confirms, as it completes, the Standard Model of fundamental physics,” Frank Wilczek wrote
  <a "="" 04="" 2012="" blogs="" href="http://www.pbs.org/wgbh/nova/blogs/physics/2012/07/thanks-mom/&lt;/a&gt; on the morning of the announcement. &lt;/p&gt;
&lt;p&gt;And yet, science thrives on observations that &lt;em&gt;don’t&lt;/em&gt; match up with predictions. Dark energy and dark matter, two of the greatest discoveries in a century of astrophysics, were hit upon because of the yawning gap between prediction and observation. If the universe is a puzzle, &lt;a href=" http:="" nova="" physics="" wgbh="" whos-afraid-of-the-dark-alternatives-to-dark-energy="" www.pbs.org="">
   dark energy
  </a>
  and
  <a href="http://www.pbs.org/wgbh/nova/blogs/physics/2012/04/whos-afraid-of-the-dark-alternatives-to-dark-matter/">
   dark matter
  </a>
  are odd-shaped pieces that puckishly refuse to be wedged into place and, in their refusal, open up the possibility that the puzzle is actually richer and more complex than we ever anticipated. The Higgs, on the other hand, snaps right into place with a satisfying “Eureka!”
 </p>
<p>
  But if the puzzle of the Standard Model is now complete, where does that leave physics?
 </p>
<p>
  “There’s this huge looming question: The Standard Model works impeccably, but it leaves a lot of things unexplained,” says David Kaiser, a physicist and science historian at MIT. The Standard Model does not account for gravity, for instance, and it provides no explanation for why the physical constants take the particular values that they do. Like the periodic table of the elements, the Standard Model is an utterly faithful census of the ingredients that make up our universe. But while we know the elegant atomic underpinnings of the motley periodic table, we are still seeking the deeper laws that are expressed in the Standard Model.
 </p>
<p>
  “I always felt the best possible thing for the LHC would be to
  <em>
   not
  </em>
  see the Higgs,” says Peter Woit, a theorist at Columbia University. That would have cracked the Standard Model wide open, perhaps giving scientists a glimpse of the deeper physics underlying it. In this sense, says Woit, “The Standard Model is a victim of its own success.” Though it fails to answer some fundamental questions about out universe, it is so impervious to experimental contradiction—so perfect in its predictions—that physicists may soon find themselves at an impasse.
 </p>
<p>
  “If this is really the Higgs, then we have completed the Standard Model,” says physicist Peter Fisher of MIT. “We have created this model that describes exquisitely the world around us. We could legitimately say that, as a field of endeavor, we’ve done all there is to be done, and ask: Is this a place to stop and reassess?”
 </p>
<p>
  Physicists do have some guesses at what may lie beyond the Standard Model. There’s
  <a href="http://www.pbs.org/wgbh/nova/blogs/physics/2012/07/supersymmetry-looking-in-natures-mirror/">
   supersymmetry
  </a>
  , for one, which suggests that elementary particles have mirror-image “superpartners” that differ in spin. Yet, to the surprise of some physicists, even the LHC has been unable to turn up any evidence of these superpartners. That suggests that, if superpartners are out there, they don’t possess the neat mirror-image symmetry we expected. Instead, the mirror that divides “us” from “them” may be warped.
 </p>
<p>
  “With the Higgs, you knew exactly what to look for,” says Woit. But the mirror of supersymmetry, if it exists, “could be warped in any arbitrary way,” leaving physicists to pursue an almost limitless game of hide-and-seek. And what if the superpartners—or other hints of new physics—are hiding where the LHC can’t find them?
 </p>
<p>
  But the story of the Higgs isn’t over yet. Over the coming months, physicists on the
  <a href="http://cms.web.cern.ch/org/cms-higgs-results">
   CMS
  </a>
  and
  <a href="http://atlas.ch/news/2012/latest-results-from-higgs-search.html">
   ATLAS
  </a>
  teams will look to see whether this thing they have found decays in the ways they expect. Perhaps the new boson will turn out to be not so “vanilla” after all. Historically, it is often the “one last measurement to nail it down” that ends up taking physics in a new direction, Kaiser points out.
 </p>
<p>
  To Nobel prize-winning physicist Frank Wilczek, finding the new boson is just the beginning. “Having won this glorious battle, I’m psyched up for complete victory. We need to see some of the new particles that low-energy supersymmetry predicts. I think that will eventually happen at the LHC.”
 </p>
<p>
  “There is also room for gratuitous, but not perverse, speculation about the Higgs being a ‘portal’ into hidden sectors—hypothetical worlds of particles that have neither strong nor weak nor electromagnetic interactions,” adds Wilczek.
 </p>
<p>
  Yet Steve Ahlen, a Boston University physicist who helped build the ATLAS detector, thinks that the story of the quest for the Higgs has a somewhat different moral: “The most impressive thing about the success of the LHC, CMS and ATLAS is that thousands of people from all over the world, supported by tax dollars from many hundreds of millions of people, achieved success without the promise of fortune, power or fame, but for the simple joy of observing the beautiful world we live in. I think there is an important lesson to be learned from that.”
 </p>
</section>

Galaxies' Gamma Rays May Illuminate Dark Matter

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<p>
  Dark matter is a riddle: Stars can feel it, but we can’t see it. It makes up 80% of the matter in the universe, yet we can only guess at what it actually is.
 </p>
<p>
  The puzzle began in 1933, when the Swiss astronomer
  <a href="http://www.amnh.org/education/resources/rfl/web/essaybooks/cosmic/p_zwicky.html">
   Fritz Zwicky
  </a>
  pointed out that galaxies in a group called the Coma Cluster seemed to be moving too quickly to be bound together by the cluster’s gravity. Stronger evidence followed in the 1960s and 1970s, when
  <a href="http://www.amnh.org/education/resources/rfl/web/essaybooks/cosmic/p_rubin.html">
   Vera Rubin’s studies of galactic rotation
  </a>
  revealed that stars at the outer edge of spiral galaxies were rotating just as fast as those in the center. That extra speed should have sent them flying out into intergalactic space. Gravity held them back—but gravity from what? When astronomers estimated the total mass contained in all the stars, gas, and dust in the galaxies, it didn’t add up: Either the laws of gravity were wrong, or some invisible “dark matter” was hiding in the galaxies’ dim margins.
 </p>
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/dwarf-galaxy-02-620.width-990_x7UuxCd.jpg"/>
<figcaption>A computer simulation of dwarf galaxy formation. Credit: Ralf Kaehler, John Wise, Tom Abel (KIPAC/SLAC)
        
    </figcaption>
</figure>
<p>
  Since those early observations, astronomers have found a wealth of
  <em>
   indirect
  </em>
  evidence for dark matter. Dark matter
  <a href="http://lsst.org/lsst/science/scientist_dark_matter">
   bends light
  </a>
  from distant galaxies and
  <a href="http://map.gsfc.nasa.gov/universe/uni_matter.html">
   shapes
  </a>
  and
  <a href="http://sci.esa.int/planck/51603-planck-sees-a-cosmic-journey-13-billion-years-in-the-making/">
   distorts
  </a>
  the cosmic microwave background radiation. “It is like seeing a dancing marionette puppet (the gravitational effects), and inferring there must be strings (dark matter) to make it move,” wrote Ben Cook, an astrophysics graduate student at the Harvard-Smithsonian Center for Astrophysics, on
  <a href="http://astrobites.org/2015/03/18/a-possible-detection-of-dark-matter-in-a-dwarf-galaxy/">
   Astrobites
  </a>
  . “To prove dark matter really exists, we must actually see the strings, not just the puppet.”
 </p>
<p>
  Today, the leading theory is that dark matter is made up of subatomic particles called weakly interacting massive particles (WIMPs), relatively heavy particles that only feel gravity and a fundamental force called the weak force. Because they don’t interact with ordinary matter via the other fundamental forces, they can pass right through walls, people, even entire planets, with just a tiny chance of actually getting close enough to a nucleus of regular matter to disturb it.
 </p>
<p>
  But, physicists still haven’t found any
  <em>
   direct
  </em>
  evidence of WIMPs, or any other kind of dark matter. No one has definitively caught a dark matter particle or spotted it doing anything other than, well, gravitating—that is, invisibly exerting a force on the ordinary matter around it. It’s certainly not for lack of trying. Using detectors like the
  <a href="http://lux.brown.edu/LUX_dark_matter/Home.html">
   Large Underground Xenon
  </a>
  (LUX) and
  <a href="http://cdms.berkeley.edu/">
   Cryogenic Dark Matter Search
  </a>
  experiments, physicists have been trying to catch the subatomic slipstreams left behind by cosmic dark matter particles, and at accelerators like the
  <a href="http://www.symmetrymagazine.org/article/the-search-for-dark-matter-at-the-lhc">
   LHC
  </a>
  , they are trying to create dark matter from scratch. At the same time, astrophysicists are searching the skies for the gamma-ray lightshows that could come from dark matter particles crashing into and annihilating each other.
 </p>
<p>
  Now, astrophysicists may finally be closing in on dark matter. In 2009, researchers Lisa Goodenough and Dan Hooper found
  <a href="http://www.nature.com/news/2009/091019/full/news.2009.1018.html">
   surprisingly bright gamma ray emission
  </a>
  coming from the center of the Milky Way. Right away, they noticed that the emission was “bumpy,” says Hooper, meaning that it was concentrated within a narrow energy band rather than being smoothly spread out across the gamma-ray spectrum. The peaked spectrum was unusual for known gamma ray sources, but it squared up well with predictions for dark matter annihilation. While Hooper and others continue to consider other possible explanations for these homegrown gamma rays—a mob of exotic pulsars, an outburst from our central supermassive black hole—Hooper thinks dark matter is the likeliest culprit. “It’s pretty easy to explain with dark matter, and pretty difficult to explain with other stuff,” says Hooper.
 </p>
<p>
  When it comes to picking up gamma ray signals, the galactic center has the advantage of proximity. But, “things are notoriously messy and complicated” in there, says Hooper. So researchers have turned their attention to dwarf galaxies, which are rich in dark matter and not much else. “The ratio of dark matter to ordinary matter in dwarfs is very, very high,” explains Hooper; dwarf galaxies may contain thousands of dark matter particles for every one ordinary particle. Otherwise placid, they make ideal hunting grounds for unusual gamma ray emission.
 </p>
<p>
  “Dwarfs are what everyone’s got their eye on,” says Hooper. But, though they are probably the commonest galaxy type in the cosmos, they are difficult to find, and a
  <a href="https://www.quantamagazine.org/20141025-dwarf-galaxies-dim-dark-matter-hopes/">
   recent search for excess gamma ray emission
  </a>
  from the few known nearby dwarfs came up empty-handed.
 </p>
<p>
  Now, that story may be changing. Combing through data from the Fermi spacecraft’s Large Area Telescope (LAT),
  <a href="http://arxiv.org/abs/1503.06209">
   two
  </a>
<a href="http://arxiv.org/abs/1503.02320">
   groups
  </a>
  of researchers found surprisingly bright gamma-ray emission coming from a newly-discovered dwarf galaxy called Reticulum 2. While the teams can’t rule out the possibility that the gamma rays are coming from a more mundane source or that they’re random background noise, they think that the gamma-ray signal matches what you’d expect from dark matter particles crashing into and annihilating each other.
 </p>
<p>
  A
  <a href="http://arxiv.org/abs/1503.02632">
   third analysis
  </a>
  , which was based on nearly identical raw data processed with a newer algorithm, turned up more gamma ray photons than expected, but not enough to make the case for a meaningful signal. It isn’t clear yet whether these apparently clashing results are truly contradictory, says Alex Geringer-Sameth of Carnegie Mellon University, lead author on the first paper to claim a detection of excess gamma rays. Once the new data set, called “Pass 8,” is made public, researchers like Hooper and Geringer-Sameth will comb through it trying to understand the source of the disagreement.
 </p>
<p>
  If the signal is real (“a HUGE if” emphasizes Garinger-Sameth), it will be a major advance for particle physics. Finally, physicists will be able to get a fix on dark matter’s mass and its annihilation process. “If the Reticulum 2 signal holds up, other groups will have a specific target to shoot for,” said Geringer-Sameth in an email. “Imagine an underground detector finding new particles streaming through the Earth that have the same properties as the new particles a hundred thousand light years away in a dwarf galaxy. It would be a very strong case that what both groups are seeing is actually the dark matter.”
 </p>
<p>
  If the observation does not hold up, though, astrophysicists will have a fresh puzzle on their hands. Fermilab physicist Alex Drlica-Wagner, who led up the team that measured the smallest gamma-ray excess, points out that a succession of gamma-ray no-shows from dwarf galaxies could scuttle the notion that galactic center gamma rays are really due to dark matter. “If the excess emission from galactic center comes from dark matter annihilation, then we should start seeing a similar gamma-ray signal coming from the dwarf galaxies. So far, we have not,” he wrote in an email.
 </p>
<p>
  “I believe that the most important question to answer in this analysis is, ‘How much dark matter is in Reticulum 2?’” says Drlica-Wagner. To find out, astronomers will be tracking the motion of stars within Reticulum 2 with optical telescopes to reveal how their velocity is being affected by dark matter’s gravity.
 </p>
<p>
  Reticulum 2 is one of nine dwarf galaxies just discovered by the
  <a href="http://www.fnal.gov/pub/presspass/press_releases/2015/DES-Dwarf-Galaxies-20150310.html">
   Dark Energy Survey
  </a>
  (DES) and is still the only dwarf galaxy from which astronomers have detected a gamma-ray excess. “Before 2006 there were only about 10 dwarf companions of the Milky Way that were known,” says Geringer-Sameth. Now, we are on the brink of a “tsunami” of new discoveries, he says, with data flooding in from the DES and a sky survey called the Panoramic Survey Telescope &amp; Rapid Response System (Pan-STARRS). In the next decade our census of dwarf galaxies may triple, Hooper estimates: “That could totally change the game.”
 </p>
<p>
  As new dwarf discoveries come in, astrophysicists can immediately begin searching for their gamma-ray counterparts in Fermi’s rich data archive. “We have data,” says Geringer-Sameth. “We just don’t know where to look.”
 </p>
<p>
  Meanwhile, Hooper and his colleagues continue to analyze gamma rays coming from the galactic center. The first study, back in 2009, was based on a single year of data from the Fermi spacecraft; now Hooper has six and a half years of measurements to work with, and he and his team can perform a more discriminating analysis of the data. Last year, a team that included Hooper and a half-dozen colleagues from around the country
  <a href="http://arxiv.org/pdf/1402.6703v2.pdf">
   showed
  </a>
  that the spectrum’s “bumpy” shape was consistent across the galactic center, and that the emission got progressively brighter closing in on the heart of the galaxy, just as predicted. Again and again, says Hooper, it “passes the test.”
 </p>
<p>
  Will the gamma ray signals stand up to the next round of scrutiny? We’ll have to wait to find out if we’re finally seeing the light at the end of the dark matter tunnel—or if there are still unknown miles of darkness ahead.
 </p>
<p>
<strong>
   Go Deeper
  </strong>
<br/>
<em>
   Editor’s picks for further reading
  </em>
</p>
<p>
  The Nature of Reality:
  <a href="http://www.pbs.org/wgbh/nova/blogs/physics/2014/01/journey-into-the-dark-realm/">
   Journey Into the Dark Realm
  </a>
<br/>
  What if dark matter isn’t just one particle, but a diverse realm of dark matter particles that experience forces that don’t affect ordinary matter? Don Lincoln explores the “dark realm.”
 </p>
<p>
  NOVA Next:
  <a href="http://www.pbs.org/wgbh/nova/next/physics/hunt-for-dark-matter/">
   Pursuing Dark Matter, Hundreds of Miles Above Earth
  </a>
<br/>
  The Alpha Magnetic Spectrometer, aboard the International Space Station, has been searching for evidence of dark matter since 2011. Veronique Greenwood reports on what it has found.
 </p>
<p>
  NOVA scienceNOW:
  <a href="http://www.pbs.org/wgbh/nova/physics/dark-matter.html">
   Dark Matter
  </a>
<br/>
  In this video, Neil deGrasse Tyson reports from a half mile underground in an abandoned mine, where scientists are using special detectors to look for dark matter particles.
 </p>
<p>
  The New York Times:
  <a href="http://www.nytimes.com/2015/03/11/us/gamma-rays-may-be-clue-on-dark-matter.html?_r=1">
   Gamma Rays May Be Clue on Dark Matter
  </a>
<br/>
  Dennis Overbye reports on new gamma ray studies of Reticulum 2.
 </p>
</section>

Gamma rays from a dwarf galaxy may help astronomers solve the riddle of dark matter.

First Direct Evidence of Cosmic Inflation

<section class="entry-content instapaper_body clearfix" itemprop="articleBody">
<div class="add-container clearfix" id="add-block-placer">
</div>
<p>
  When Alan Guth proposed the theory of
  <a href="http://www.amazon.com/The-Inflationary-Universe-Alan-Guth/dp/0201328402">
   cosmic inflation
  </a>
  almost 35 years ago, he wondered whether it would ever be possible to prove his hypothesis that the universe ballooned up exponentially in the first moments after the Big Bang. There was ample
  <a href="http://wmap.gsfc.nasa.gov/universe/bb_cosmo_infl.html">
   indirect evidence
  </a>
  : the universe’s surprisingly uniform temperature, the apparent “flatness” of spacetime, and the conspicuous absence of magnetic monopoles. In the years that followed, astronomers used satellites like
  <a href="http://www.skyandtelescope.com/news/3311206.html">
   WMAP
  </a>
  and
  <a href="http://www.nature.com/news/planck-snaps-infant-universe-1.12671">
   Planck
  </a>
  to search for echoes of the inflationary era in the cosmic microwave background radiation. Their results lined up with many inflationary predictions, but fell short of being the “smoking gun” that would have had Guth and other theorists popping their champagne.
 </p>
<div class="flex-video">
<div class="flex-video">
<iframe allowfullscreen="" frameborder="0" height="439" src="https://www.youtube.com/embed/ZlfIVEy_YOA?feature=oembed" width="780">
</iframe>
</div>
</div>
<p>
  Well, bring on the bubbly: Using a telescope called
  <a href="http://www.cfa.harvard.edu/CMB/bicep2/">
   BICEP2
  </a>
  , a team of astronomers led by John Kovac (Harvard-Smithsonian Center for Astrophysics) has
  <a href="http://bicepkeck.org/b2_respap_arxiv_v1.pdf">
   detected a polarization pattern
  </a>
  in the microwave background radiation that is the first direct evidence for cosmic inflation. This “B-mode” polarization is a “twisty” pattern created by gravitational waves. The discovery is also the first direct image of gravitational waves.
 </p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/10mspt_mars_h_620.width-990_ZxNKyy9.jpg"/>
<figcaption>The 10-meter South Pole Telescope and the BICEP (Background Imaging of Cosmic Extragalactic Polarization) Telescope at Amundsen-Scott South Pole Station. Credit: Keith Vanderlinde, National Science Foundation
        
    </figcaption>
</figure>
<p>
  The news is generating plenty of buzz.  Here are our picks from some of the best coverage we’ve seen so far:
 </p>
<p>
<strong>
   Nature
  </strong>
  :
  <a href="http://www.nature.com/news/how-astronomers-saw-gravitational-waves-from-the-big-bang-1.14885">
   How astronomers saw gravitational waves from the Big Bang
  </a>
<br/>
  A suite of special coverage, including an explainer on gravitational waves and an interview with John Kovac, who maintains that he, for one, has held off on the champagne:
 </p>
<blockquote>
<p>
   My role in this process has been to remain calm at all times. The time to celebrate, I think, will be once we have published our results and presented them to the scientific community.
  </p>
</blockquote>
<p>
<strong>
   The New York Times
  </strong>
  :
  <a href="http://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html">
   Detection of Waves in Space Buttresses Landmark Theory of Big Bang
  </a>
</p>
<p>
  Dennis Overbye talks (or emails) with everyone-who’s-anyone as he traces the history of inflationary theory from its inception in 1979 to its greatest confirmation yet today, closing with the possibility that inflation is continuing elsewhere in the cosmos:
 </p>
<blockquote>
<p>
   Most of the hundred or so models that have been spawned by Dr. Guth’s original vision suggest that inflation, once started, is eternal. Even as our own universe settled down to a comfortable homey expansion with atoms, stars and planets, the rest of the cosmos will continue blowing up, spinning off other bubbles here and there endlessly, a concept known as the multiverse.
  </p>
</blockquote>
<p>
<strong>
   WIRED
  </strong>
  :
  <a href="http://www.wired.com/wiredscience/2014/03/gravitational-waves-b-mode-inflation/">
   Cosmologists Finally Capture an Elusive Signal From the Beginning of Time
  </a>
</p>
<p>
  Adam Mann explains “how primordial B-modes could be so important if you’ve never heard of them” and highlights the need for followup observations to confirm the result:
 </p>
<blockquote>
<p>
   In fact, BICEP’s data is somewhat at odds with other experiments, such as the Planck space telescope, which have carefully mapped the CMB but not seen primordial B-modes. But it’s also possible that these other teams simply missed what BICEP is seeing and, now that they know how to look for the primordial B-modes, can confirm the results fairly quickly using already existing datasets, perhaps within a matter of weeks. No doubt, other collaborations will begin taking new data to try and detect the primordial B-modes on their own.
  </p>
</blockquote>
<p>
<strong>
   Sky and Telescope
  </strong>
  :
  <a href="http://www.skyandtelescope.com/news/Proof-of-Inflationary-Universe-To-Be-Announced-Monday-250522521.html">
   Proof of Inflationary Universe To Be Announced Today?
  </a>
</p>
<p>
  In advance of today’s announcement, Sky and Telescope’s Alan MacRobert rounded up coverage of the search for B-modes and  explained what B-modes are and how gravitational waves create them.
 </p>
</section>

Kate Becker

Articles