Contents | Zoom in | Zoom outFor navigation instructions please click here Search Issue | Next Page :Xjj`e`jcXjkm`\nf] ?fnfliYiX`ejal[^\ J\Zli`kpg`k]Xccjn`k_ J8KLIEJI@E>J D@J@E=FID8K@FE ;@>@K8CDFE<P AMERICAN IY_[dj_ijEfm\dY\iÆ;\Z\dY\i)'(. nnn%Xd\i`ZXejZ`\ek`jk%fi^_______________________ JfZ`XcA\kCX^ ?fnk_\ZcXj_ Y\kn\\eY`fcf^`ZXc ZcfZbjXe[df[\ie c`]\jkpc\_Xidj glYc`Z_\Xck_ ,%0, Contents | Zoom in | Zoom outFor navigation instructions please click here Search Issue | Next Page qM qMqM American Scientist Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next Page qMqM Qma gs THE WORLD’S NEWSSTAND® Symposium on Atmospheric Chemistry, Climate, and Health November 10, 2017 t Raleigh Convention Center Raleigh, North Carolina t #SigmaXimtg IMAGE BY NASA Featured Speakers David Archer, PhD Barbara Finlayson-Pitts, The University of Chicago PhD University of California, Irvine Humanity and Global Warming: Views from the The Past is Prologue: Carbon Cycle Lessons Learned for Science-Based Policies to Address Air Quality and Climate C. Arden Pope III, PhD A. R. Ravishankara, PhD Brigham Young University Colorado State University Air Pollution and Health: The Ozone Hole: From Scientific and Public Policy Discovery to Recovery Controversies Jeffrey Shaman, PhD Columbia University Simulation and Forecast of Infectious Disease: Environmental Determinants and Transmission Dynamics Followed by the Student Research Conference on November 11 t [email protected]_____________________ sigmaxi.org/fallsymposium-src qM qMqM American Scientist Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next Page qMqM Qma gs THE WORLD’S NEWSSTAND® qM qMqM American Scientist Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next Page qMqM Qma gs THE WORLD’S NEWSSTAND® AMERICAN IY_[dj_ij Lebkc['&+DkcX[h,Del[cX[hÄ:[Y[cX[h(&'- Departments Feature Articles 322 From the Editors 348 364 323 Letters to the Editors 326 Spotlight Proprietary algorithms 328 Infographic Living with fire 330 First Person: Sally C. Seidel New insights on particle physics 332 Sightings Seeing the heart’s power 334 Briefings 335 Computing Science Bitcoins maybe; blockchains likely Peter J. Denning and Ted G. Lewis 340 Engineering 348 Adapting Your Body Clock to a 364 The New Language of Problematic pedestrian bridges 24-Hour Society Mathematics Henry Petroski Can new research help address the dis- Is it possible to take all words out of 344 Perspective connect between the body’s sleep-wake mathematical expressions? cycle and the rhythms of modern life? The forgotten mystery of inertia Daniel S. Silver Alexis Webb and Erik Herzog Tony Rothman 372 The Persistence and Peril of Scientists’ 356 Cassini and the Rings of Saturn Misinformation As one of its final scientific feats, Many challenges arise while battling Nightstand Cassini conducted a detailed tour of the widespread falsehoods. 376 Book Reviews material encircling the giant planet. Brian G. Southwell, Emily A. Picturing science rBig data in law Matthew S. Tiscareno Thorson, and Laura Sheble enforcement From Sigma Xi 356 381 Sigma Xi Today Q&A with new editor-in-chief of American Scientist rSymposium will address climate and health r Members share solar eclipse stories rNew quarterly conversations 372 The Cover Technology has extended the times of day when people can be active and has allowed for connectivity at any time of day. A growing body of research shows that the biological clock is affected by light exposure, especially at certain times of day, which in turn can affect all sorts of biological processes necessary for health, including sleep, focus, and metabolism. More people seem to be experiencing social jet lag, when our body rhythms are out of sync with the day-night cycle. This lack of synchrony can have serious public health consequences; for example, it has been linked to sleep disorders, obesity, and mental disorders. In “Adapting Your Body Clock to a 24-Hour Society” (pages 348–355), circadian biologists Alexis Webb and Erik Herzog explain how the biological clock sets and keeps time, and what solutions are under study to help people sync up with healthy daily routines for sleeping and eating. (Cover illustration by Michael Morgenstern.) qM qMqM American Scientist Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next Page qMqM Qma gs THE WORLD’S NEWSSTAND® qM qMqM American Scientist Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next Page qMqM Qma gs THE WORLD’S NEWSSTAND® FROM THE EDITORS AMERICAN Modern Challenges IY_[dj_ij decade ago, the robotic spacecraft Cassini had nnn%Xd\i`ZXejZ`\ek`jk%fi^_______________ Aalready become a huge success. It had released its Huygens probe onto Saturn’s moon Titan, and it was returning spectacular imagery of the giant VOLUME 105, NUMBER 6 planet itself, as well as its other moons. At that time, we asked Carolyn Porco, leader of the imaging team Editor-in-Chief Fenella Saunders for the Cassini-Huygens mission and director of the Senior Consulting Editor Corey S. Powell Cassini Imaging Central Laboratory for Operations, Digital Features Editor Katie L. Burke to fill in American Scientist readers on the mission Contributing Editors Sandra J. Ackerman, Marla Broadfoot, Catherine Clabby, Brian Hayes, results so far. Her resulting essay in the July–August Anna Lena Phillips, Diana Robinson, David 2007 issue showcased the early results from the first Schoonmaker, Michael Szpir, Flora Taylor 1,000 days of the mission. Editorial Associate Mia Evans In this issue, we are returning to Cassini as its mis- sion recently came to a preplanned end. To preclude Cassini from crashing into Art Director Barbara J. Aulicino one of Saturn’s moons as it ran out of propellant and potentially spreading ter- restrial contamination there, the spacecraft was instead deliberately plunged into SCIENTISTS’ NIGHTSTAND Saturn. But before its final encounter with the planet, Cassini spent much of the Editor Dianne Timblin final year of its mission taking a detailed look at Saturn’s rings. As Matthew S. AMERICAN SCIENTIST ONLINE Tiscareno explains in “Cassini and the Rings of Saturn” (pages 356–363), this con- Digital Managing Editor Robert Frederick cluding year has been practically a whole new mission for the spacecraft, with some spectacular results. Publisher Jamie L. Vernon Space exploration uses remarkable technology, but the devices we use daily are also pretty amazing, even if we’re not paying attention to how they work. ADVERTISING SALES This issue tackles from multiple angles topics related to technology and how it af- BEWFSUJTJOH!BNTDJPSHt___________ fects us. In our cover story, Alexis Webb and Erik Herzog look at the role that late- EDITORIAL AND SUBSCRIPTION night viewing of backlit devices, such as cell phones and tablets, is having on our CORRESPONDENCE biological clocks, and our health, as a result. In “Adapting Your Body Clock to a American Scientist 24-Hour Society” (pages 348–355), the authors look at research that might help P.O. Box 13975 reset our biological clocks to be more in tune with our modern style of living. 3FTFBSDI5SJBOHMF1BSL /$ Mobile devices offer us the convenience of information at our fingertips, but tGBY are they also a conduit for making us more susceptible to falsehoods? In “The FEJUPST!BNTDJPOMJOFPSHtTVCT!BNTDJPSH____________ ________ Persistence and Peril of Misinformation,” Brian G. Southwell, Emily A. Thorson, PUBLISHED BY SIGMA XI, THE SCIENTIFIC and Laura Sheble review what is known about how people evaluate information RESEARCH HONOR SOCIETY and discuss how knowledge of these processes could be used to battle hoaxes President Stuart L. Cooper and fake news. Treasurer David Baker Two articles in this issue discuss machine learning and its supporting algo- President-Elect Joel R. Primack rithms, which are increasingly framing our lives whether we are aware of it or Immediate Past President Tee Guidotti not. In the Spotlight section (pages 326–327), Simson L. Garfinkel reports on a Executive Director Jamie L. Vernon recent panel discussing proprietary algorithms and who should have access to American Scientist gratefully acknowledges how they work. Garfinkel points out that these types of algorithms not only can support for “Engineering” through the Leroy control what music you hear or what news you see on social media, but also are Record Fund. increasingly used to screen which job applicants to interview or determine how long a jail sentence should be—and there is currently little recourse for those af- Sigma Xi, The Scientific Research Honor fected to dispute the results from the software. Society is a society of scientists and engineers, One specific use of machine-learning algorithms is what’s called predictive polic- GPVOEFEJOUPSFDPHOJ[FTDJFOUJmD ing, where law enforcement agencies use software to help determine everything achievement. A diverse organization of from where officers patrol to which members of the public might be more likely members and chapters, the Society fosters to be a victim of a crime. In the Scientists’ Nightstand section (pages 376–380), an interaction among science, technology, and society; encourages appreciation and support excerpt of Andrew Guthrie Ferguson’s latest book, The Rise of Big Data Policing, of original work in science and technology; and digs into such programs, and why efforts in New Orleans were successful when QSPNPUFTFUIJDTBOEFYDFMMFODFJOTDJFOUJmDBOE similar programs in other cities didn’t