Tagged: Scientific American Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 1:28 pm on February 8, 2019 Permalink | Reply
    Tags: ESA Galileo navigation system, , ESA's answer to USA GPS, Scientific American   

    From Scientific American: “Wayward Satellites Test Einstein’s Theory of General Relativity” 

    Scientific American

    From Scientific American

    February 8, 2019
    Megan Gannon

    The botched launch of two Galileo navigation probes made for an unexpected experiment.

    Galileo satellite. Credit: P. Carril and ESA

    ESA Galileo’s navigagtion constellation

    In August 2014 a rocket launched the fifth and sixth satellites of the Galileo global navigation system, the European Union’s $11-billion answer to the U.S.’s GPS. But celebration turned to disappointment when it became clear that the satellites had been dropped off at the wrong cosmic “bus stops.” Instead of being placed in circular orbits at stable altitudes, they were stranded in elliptical orbits useless for navigation.

    The mishap, however, offered a rare opportunity for a fundamental physics experiment. Two independent research teams—one led by Pacôme Delva of the Paris Observatory in France, the other by Sven Herrmann of the University of Bremen in Germany—monitored the wayward satellites to look for holes in Einstein’s general theory of relativity.

    “General relativity continues to be the most accurate description of gravity, and so far it has withstood a huge number of experimental and observational tests,” says Eric Poisson, a physicist at the University of Guelph in Ontario, who was not involved in the new research. Nevertheless, physicists have not been able to merge general relativity with the laws of quantum mechanics, which explain the behavior of energy and matter at a very small scale. “That’s one reason to suspect that gravity is not what Einstein gave us,” Poisson says. “It’s probably a good approximation, but there’s more to the story.”

    Einstein’s theory predicts time will pass more slowly close to a massive object, which means that a clock on Earth’s surface should tick at a more sluggish rate relative to one on a satellite in orbit. This time dilation is known as gravitational redshift. Any subtle deviation from this pattern might give physicists clues for a new theory that unifies gravity and quantum physics.

    Even after the Galileo satellites were nudged closer to circular orbits, they were still climbing and falling about 8,500 kilometers twice a day. Over the course of three years Delva’s and Herrmann’s teams watched how the resulting shifts in gravity altered the frequency of the satellites’ superaccurate atomic clocks. In a previous gravitational redshift test, conducted in 1976, when the Gravity Probe-A suborbital rocket was launched into space with an atomic clock onboard, researchers observed that general relativity predicted the clock’s frequency shift with an uncertainty of 1.4 × 10–4.

    The new studies, published last December in Physical Review Letters, again verified Einstein’s prediction—and increased that precision by a factor of 5.6. So, for now, the century-old theory still reigns.

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 10:49 am on January 30, 2019 Permalink | Reply
    Tags: , , , , Finding Alien Life May Require Giant Telescopes Built in Orbit, How big such a telescope must be to offer a reasonable chance of success in that interstellar quest depends on life’s still-unknown cosmic prevalence, iSAT-in-Space Assembled Telescope” study, NASA’s still-in-development Space Launch System (SLS), Scientific American, The forces demanding supersize space telescopes are straightforward: The larger a scope’s light-collecting mirror is the deeper and finer its cosmic gaze, Two of NASA’s pinnacle projects—the International Space Station (ISS) and the Hubble Space Telescope—owe their existence to orbital construction work   

    From Scientific American: “Finding Alien Life May Require Giant Telescopes Built in Orbit” 

    Scientific American

    From Scientific American

    December 12, 2018 [Just presented in social media.]
    Lee Billings

    Scientific American reports on new efforts from NASA and other federal agencies seeking to service and assemble large structures—such as life-finding telescopes—in space.

    Astronauts repair and upgrade the Hubble Space Telescope during the first servicing mission to that orbital observatory, in 1993. NASA is now studying how telescopes far larger than Hubble might someday be assembled and serviced in space by astronauts or robots. Credit: NASA.

    After snapping the final piece into place with a satisfying “click” she feels through her spacesuit gloves, the astronaut pauses to appreciate the view. Her reflection swims before her in a silvery disk the size of three tennis courts; for a moment she feels like a bug floating on a darkened pond. Composed of hundreds of interlocking metallic hexagons like the one she has just installed, the disk is a colossal mirror 30 meters wide, the starlight-gathering eye of the largest space telescope ever built. From her perch on the robotic arm of a small space station, Earth is a tiny blue and white orb she could cover with an outstretched thumb, dwarfed by the bright and silent moon spinning thousands of kilometers below her feet.

    Although this scene remains the stuff of science fiction, an ad hoc assemblage of scientists, engineers and technocrats now say it is well on its way to becoming reality. Under the auspices of a modest NASA-sponsored initiative, this diverse group is gauging how the space agency might build bigger, better space telescopes than previously thought possible—by constructing and servicing them in space. The effort, formally known as the “in-Space Assembled Telescope” study (iSAT), is part of a long trend in which science advances by piggybacking on technologies created for more practical concerns.

    For example, the development of surveillance satellites and warhead-carrying rockets during the 20th-century cold war also catalyzed the creation of robotic interplanetary probes and even NASA’s crewed Apollo lunar missions. Similarly, in the 21st century a soaring military and industrial demand for building and servicing satellites in orbit could lead to dramatically enhanced space telescopes capable of definitively answering some of science’s biggest questions—such as whether or not we are alone. “The iSAT is a program that can be NASA’s next Apollo,” says study member Matt Greenhouse, an astrophysicist at the space agency’s Goddard Space Flight Center. “And the science enabled by the iSAT would likely include discovery of extraterrestrial life—an achievement that would eclipse Apollo in terms of impact on humanity.”

    NASA Goddard Space Flight Center campus

    “And the science enabled by the iSAT would likely include discovery of extraterrestrial life—an achievement that would eclipse Apollo in terms of impact on humanity.”

    Ready for Prime Time

    In some respects, building and repairing spacecraft in space is a revolution that has already arrived, merely kept under the radar by a near-flawless track record that makes it seem deceptively routine. Two of NASA’s pinnacle projects—the International Space Station (ISS) and the Hubble Space Telescope—owe their existence to orbital construction work.


    NASA/ESA Hubble Telescope

    Assembled and resupplied in orbit over two decades, the ISS is now roughly as big as a football field and has more living space than a standard six-bedroom house. And only space-based repairs allowed Hubble to become the world’s most iconic and successful telescope, after a space shuttle crew on a first-of-its-kind servicing mission in 1993 fixed a crippling defect in the observatory’s primary mirror.


    NASA COSTAR installation

    Astronauts have since conducted four more Hubble servicing missions, replacing equipment and upgrading instruments to leave behind an observatory reborn.

    COSTAR was removed from HST in 2009 during the fifth servicing mission and replaced by the Cosmic Origins Spectrograph. It is now on exhibit in the Smithsonian’s National Air and Space Museum.

    NASA Hubble Cosmic Origins Spectrograph

    An artist’s rendition of the upcoming Dragonfly mission, a collaboration between NASA and Space Systems Loral to demonstrate technologies required for orbital construction. Dragonfly’s robotic arm (inset) will assemble and deploy reflectors to create a large radio antenna when the mission launches sometime in the 2020s. Credit: NASA and SSL.

    Today multiple projects are carrying the momentum forward from those pioneering efforts, cultivating powerful new capabilities. Already NASA and the Pentagon’s Defense Advanced Research Projects Agency (DARPA) as well as private-sector companies such as Northrop Grumman and Space Systems Loral (SSL) are building robotic spacecraft for launch in the next few years on lengthy missions to refuel, repair, re-position and upgrade governmental and commercial satellites. Those spacecraft—or at least the technologies they demonstrate—could also be used to assemble telescopes and other large structures in space such as those associated with NASA’s perennial planning for human missions to the moon and Mars. Last year—under the auspices of a “partnership forum” between NASA, the U.S. Air Force and National Reconnaissance Office—the space agency took the lead on crafting a national strategy for further public and private development of in-space assembly in the 2020s and beyond.

    These trends could end what some experts see as a “dark age” in space science and exploration. “Imagine a world where once your car runs low on fuel, instead of driving to the gas station you take it to the junkyard and abandon it. Imagine a world where once you’ve moved into your house for the first time you have no way of ever getting more groceries inside, having a plumber come to fix a leaky pipe or any way to bring in and install a new TV. Imagine a world where we all live in tents that we can carry on our backs and no one thinks to build anything larger or more permanent. That seems crazy, doesn’t it?” says iSAT study member Joe Parrish, a program manager for DARPA’s Tactical Technology Office who helms its Robotic Servicing of Geosynchronous Satellites (RSGS) mission. “But that’s exactly the world we live in right now with our $1-billion–class assets in space. … I think we will look back on the era before on-orbit servicing and assembly the way we now look back on the era when leeches were used to treat diseases.”

    Bigger Is Better

    The fundamental reality behind the push for in-space assembly is easy to understand: Anything going to space must fit within the rocket taking it there. Even the very biggest—the mammoth 10-meter rocket fairing of NASA’s still-in-development Space Launch System (SLS)—would be unable to hold something like the ISS or even the space agency’s smaller “Gateway,” a moon-orbiting space station proposed for the 2020s.

    NASA Space Launch System depiction

    Launching such megaprojects piece by piece, for orbital assembly by astronauts or robots, is literally the only way to get them off the ground. And coincidentally, even though massive “heavy lift” rockets such as the SLS remain ruinously expensive, the midsize rockets that could support orbital assembly with multiple launches are getting cheaper all the time.

    The forces demanding supersize space telescopes are straightforward, too: The larger a scope’s light-collecting mirror is, the deeper and finer its cosmic gaze. Simply put, bigger is better when it comes to telescopes—especially ones with transformative objectives such as tracking the coalescence of galaxies, stars and planets throughout the universe’s 13.8-billion-year history, learning the nature of dark matter and dark energy, and seeking out signs of life on habitable worlds orbiting other stars. Most of today’s designs for space telescopes pursuing such alluring quarry cap out with mirrors as wide as 15 meters—but only because that is the approximate limit of what could be folded to fit within a heavy-lift rocket like the SLS.

    Astronomers have long fantasized about building space observatories even bigger, with mirrors 30 meters wide or more—rivaling the sizes of ground-based telescopes already under construction for the 2020s. Assembled far above our planet’s starlight-scattering atmosphere, these behemoths could perform feats the likes of which ground-based observers can only dream, such as taking pictures of potentially Earth-like worlds around a huge sample of other stars to determine whether those worlds are actually habitable—or even inhabited. If our own Earth is any example to go by, life is a planetary phenomenon that can transform the atmosphere and surface of its home world in clearly recognizable ways; provided, that is, one has a telescope big enough to see such details across interstellar distances.

    A recent “Exoplanet Science Strategy” report from the National Academies of Sciences, Engineering and Medicine said NASA should take the lead on a major new space telescope that begins to approach that grand vision—something capable of surveying hundreds (or at least dozens) of nearby stars for snapshots of potential exo-Earths. That recommendation (itself an echo from several previous prestigious studies) is reinforced by the core conclusion of another new Academies report which calls for the agency to make the search for alien life a more fundamental part of its future space exploration activities. These reports build on the growing consensus that our galaxy likely holds billions of potentially habitable worlds, courtesy of statistics from NASA’s recently deceased Kepler space telescope and the space agency’s newly launched Transiting Exoplanet Survey Satellite.

    NASA/Kepler Telescope


    Whether viewed through the lens of scientific progress, technological capability or public interest, the case for building a life-finding space telescope is stronger than ever before—and steadily strengthening. Sooner or later it seems NASA will find itself tasked with making this longed-for giant leap in the search for life among the stars.

    How big such a telescope must be to offer a reasonable chance of success in that interstellar quest depends on life’s still-unknown cosmic prevalence. With a bit of luck, one with a four-meter mirror might suffice to hit the jackpot, locating an inhabited exo-Earth around one of our sun’s nearest neighboring stars. But if the cosmos is less kind and the closest life-bearing worlds are much farther away, something in excess of the 15-meter limit imposed by near-future rockets could be necessary to sniff out any living planets within our solar system’s corner of the galaxy. In short, in-space assembly may offer the only viable path to completing the millennia-long effort to end humanity’s cosmic loneliness.

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 11:37 am on December 10, 2018 Permalink | Reply
    Tags: Advances like those made by Hubble are possible only through sustained publicly-funded research, Arthur “Art” Code, , , , , Lyman Spitzer, , OAO-2, Scientific American, Space Astronomy Laboratory at UW–Madison,   

    From Scientific American: “The World’s First Space Telescope” 

    Scientific American

    From Scientific American

    December 7, 2018
    James Lattis

    50 years ago, astronomers launched the Orbiting Astronomical Observatory, whose descendants include the Hubble, Spitzer and James Webb telescopes.

    In July 1958, an astronomer at the University of Wisconsin–Madison named Arthur “Art” Code received a telegram from the fledgling Space Science Board of the National Academy of Sciences. The agency wanted to know what he and his colleagues would do if given the opportunity to launch into Earth’s orbit an instrument weighing up to 100 pounds.

    Code, newly-minted director of the University’s Washburn Observatory, had something in mind. His department was already well known for pioneering a technique for measuring the light emitted by celestial objects, called photoelectric photometry, and Code had joined the university with the intent of adapting it to the burgeoning field of space astronomy.

    He founded the Space Astronomy Laboratory at UW–Madison and, with his colleagues, proposed to launch a small telescope equipped with a photoelectric photometer, designed to measure the ultraviolet (UV) energy output of stars—a task impossible from Earth’s surface. Fifty years ago, on December 7, 1968, that idea culminated in NASA’s launch of the first successful space-based observatory: the Orbiting Astronomical Observatory, or OAO-2.

    NASA U Wisconsin Orbiting Astronomical Observatory OAO-2

    With it was born the era of America’s Great Observatories, bearing the Hubble, Spitzer, Chandra and Compton space telescopes, a time during which our understanding of the universe repeatedly deepened and transformed.

    NASA/ESA Hubble Telescope

    NASA/Spitzer Infrared Telescope

    NASA/Chandra X-ray Telescope

    NASA Compton Gamma Ray Observatory

    Today, dwindling political appetite and lean funding threaten our progress. Contemporary projects like the James Webb Space Telescope flounder, and federal budgets omit promising projects like the Wide Field Infrared Survey Telescope (WFIRST).

    NASA/ESA/CSA Webb Telescope annotated


    In celebrating the half century since OAO-2’s launch, we are reminded that major scientific achievements like it become part of the public trust, and to make good on the public trust, we must repay our debt to history by investing in our future. Advances like those made by Hubble are possible only through sustained, publicly-funded research.

    These first investments originated in the late 1950s, during the space race between the U.S. the USSR. They led to economic gains in the private sector, technological and scientific innovations, and the birth of new fields of exploration.

    Astronomer Lyman Spitzer, considered the father of the Hubble Space Telescope, first posited the idea of space-based observing seriously in a 1946 RAND Corporation study. By leaving Earth’s atmosphere, he argued, astronomers could point telescopes at and follow nearly anything in the sky, from comets to galaxy clusters, and measure light in a broader range of the electromagnetic spectrum.

    When Code pitched Wisconsin’s idea to the Space Board, the result was NASA funding to create part of the scientific payload for OAO. The agency went to work planning a spacecraft that could support these astronomical instruments. The Cook Electric Company in Chicago and Grumman Aircraft Engineering Corporation in New York won contracts to help pull it off.

    The payload, named the Wisconsin Experiment Package (WEP), bundled five telescopes equipped with photoelectric photometers and two scanning spectrophotometers, all with UV capabilities. The Massachusetts Institute of Technology created a package of X-ray and gamma detectors.

    Scientists and engineers had to make the instruments on OAO both programmable and capable of operating autonomously between ground contacts. Because repairs were impossible once in orbit, they designed redundant systems and operating modes. Scientists also had to innovate systems for handling complex observations, transmitting data to Earth digitally (still a novelty in those days), and for processing data before they landed in the hands of astronomers.

    The first effort, OAO-1, suffered a fatal power failure after launch in 1966, and the scientific instruments were never turned on. But NASA reinvested, and OAO-2 launched with a new WEP from Wisconsin, and this time a complementary instrument from the Smithsonian Astrophysical Observatory, called Celescope, that used television camera technology to produce images of celestial objects emitting UV light. Expected to operate just one year, OAO-2 continued to make observations for four years.

    Numerous “guest” astronomers received access to the instruments during the extended mission. Such collaborations ultimately led to the creation of the Space Telescope Science Institute, which Code helped organize as acting director in 1981.

    And the data yielded many scientific firsts, including a modern understanding of stellar physics, surprise insights into stellar explosions called novae, and exploration of a comet that had far-reaching implications for theories of planet formation and evolution.

    To be responsible beneficiaries of such insights, we must remember that just as we are yesterday’s future, the firsts of tomorrow depend on today. We honor that public trust only by continuing to fund James Webb, WFIRST, and other projects not yet conceived.

    In the forward of a 1971 volume publishing OAO-2’s scientific results, NASA’s Chief of Astronomy Nancy G. Roman wrote: “The performance of this satellite has completely vindicated the early planners and has rewarded … the entire astronomical community with many exciting new discoveries and much important data to aid in the unravelling of the secrets of the stars.”

    Let’s keep unraveling these stellar secrets.

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 10:52 am on October 15, 2018 Permalink | Reply
    Tags: , , , , , NASA Viking 2 Lander, Scientific American, Search for Alien Life Should Be a Fundamental Part of NASA New Report Urges, , The Viking missions to Mars were the last time the space agency performed a direct explicit search for life on another world   

    From Scientific American: “Search for Alien Life Should Be a Fundamental Part of NASA, New Report Urges” 

    Scientific American

    From Scientific American

    October 15, 2018
    Adam Mann

    An image taken by the Viking 2 lander from Utopia Planitia on the surface of Mars in 1976. The Viking missions to Mars were the last time the space agency performed a direct, explicit search for life on another world. Credit: NASA

    NASA Viking 2 Lander

    For decades many researchers have tended to view astrobiology as the underdog of space science. The field—which focuses on the investigation of life beyond Earth—has often been criticized as more philosophical than scientific, because it lacks in tangible samples to study.

    Now that is all changing. Whereas astronomers once knew of no planets outside our solar system, today they have thousands of examples. And although organisms were previously thought to need the relatively mild surface conditions of our world to survive, new findings about life’s ability to persist in the face of extreme darkness, heat, salinity and cold have expanded researchers’ acceptance that it might be found anywhere from Martian deserts to the ice-covered oceans of Saturn’s moon Enceladus.

    Highlighting astrobiology’s increasing maturity and clout, a new Congressionally mandated report from the National Academy of Sciences (NAS) [National Academies Press] urges NASA to make the search for life on other worlds an integral, central part of its exploration efforts. The field is now well set to be a major motivator for the agency’s future portfolio of missions, which could one day let humanity know whether or not we are alone in the universe. “The opportunity to really address this question is at a critically important juncture,” says Barbara Sherwood Lollar, a geologist at the University of Toronto and chair of the committee that wrote the report.

    The astronomy and planetary science communities are currently gearing up to each perform their decadal surveys—once-every-10-year efforts that identify a field’s most significant open questions—and present a wish list of projects to help answer them. Congress and government agencies such as NASA look to the decadal surveys to plan research strategies; the decadals, in turn, look to documents such as the new NAS report for authoritative recommendations on which to base their findings. Astrobiology’s reception of such full-throated encouragement now may boost its odds of becoming a decadal priority.

    Another NAS study released last month could be considered a second vote in astrobiology’s favor. This “Exoplanet Science Strategy” report recommended NASA lead the effort on a new space telescope that could directly gather light from Earth-like planets around other stars. Two concepts, the Large Ultraviolet/Optical/Infrared (LUVOIR) telescope and the Habitable Exoplanet Observatory (HabEx), are current contenders for a multibillion-dollar NASA flagship mission that would fly as early as the 2030s.

    NASA Large UV Optical Infrared Surveyor (LUVOIR)

    NASA Habitable Exoplanet Imaging Mission (HabEx) The Planet Hunter

    Either observatory could use a coronagraph, or “starshade”—objects that selectively block starlight but allow planetary light through—to search for signs of habitability and of life in distant atmospheres.

    NASA JPL Starshade


    JPL-Caltech is developing coronagraph technology to enable direct imaging and spectroscopy of exoplanets using the Astrophysics Focused Telescope Assets (AFTA) on the NASA Wide-Field Infrared Survey Telescope (WFIRST).

    But either would need massive and sustained support from outside astrobiology to succeed in the decadal process and beyond.

    There have been previous efforts to back large, astrobiologically focused missions such as NASA’s Terrestrial Planet Finder concepts—ambitious space telescope proposals in the mid-2000s that would have spotted Earth-size exoplanets and characterized their atmospheres (if these projects had ever made it off the drawing board). Instead, they suffered ignominious cancellations that taught astrobiologists several hard lessons. There was still too little information at the time about the number of planets around other stars, says Caleb Scharf, an astrobiologist at Columbia University, meaning advocates could not properly estimate such a mission’s odds of success. His community had yet to realize that in order to do large projects it needed to band together and show how its goals aligned with those of astronomers less professionally interested in finding alien life, he adds. “If we want big toys,” he says. “We need to play better with others.”

    There has also been tension in the past between the astrobiological goals of solar system exploration and the more geophysics-steeped goals that traditionally underpin such efforts, says Jonathan Lunine, a planetary scientist at Cornell University. Missions to other planets or moons have limited capacity for instruments, and those specialized for different tasks often end up in ferocious competitions for a slot onboard. Historically, because the search for life was so open-ended and difficult to define, associated instrumentation lost out to hardware with clearer, more constrained geophysical research priorities. Now, Lunine says, a growing understanding of all the ways biological and geologic evolution are interlinked is helping to show that such objectives do not have to be at odds. “I hope that astrobiology will be embedded as a part of the overall scientific exploration of the solar system,” he says. “Not as an add-on, but as one of the essential disciplines.”

    Above and beyond the recent NAS reports, NASA is arguably already demonstrating more interest in looking for life in our cosmic backyard than it has for decades. This year the agency released a request for experiments that could be carried to another world in our solar system to directly hunt for evidence of living organisms—the first such solicitation since the 1976 Viking missions that looked for life on Mars. “The Ladder of Life Detection,” a paper written by NASA scientists and published in Astrobiology in June, outlined ways to clearly determine if a sample contains extraterrestrial creatures—a goal mentioned in the NAS report. The document also suggests NASA partner with other agencies and organizations working on astrobiological projects, as the space agency did last month when it hosted a workshop with the nonprofit SETI Institute on the search for “techno-signatures,” potential indicators of intelligent aliens.

    “I think astrobiology has gone from being something that seemed fringy or distracting to something that seems to be embraced at NASA as a major touchstone for why we’re doing space exploration and why the public cares,” says Ariel Anbar, a geochemist at Arizona State University in Tempe.

    All this means is astrobiology’s growing influence is helping bring what once were considered outlandish ideas into reality. Anbar recalls attending a conference in the early 1990s, when then–NASA Administrator Dan Goldin displayed an Apollo-era image of Earth from space and suggested the agency try to do the same thing for a planet around another star.

    “That was pretty out there 25 years ago,” he says. “Now it’s not out there at all.”

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 11:11 am on August 17, 2018 Permalink | Reply
    Tags: , , , Is Gravity Quantum?, , , , Scientific American   

    From Scientific American: “Is Gravity Quantum?” 

    Scientific American

    From Scientific American

    August 14, 2018
    Charles Q. Choi

    Artist’s rendition of gravitational waves generated by merging neutron stars. The primordial universe is another source of gravitational waves, which, if detected, could help physicists devise a quantum theory of gravity. Credit: R. Hurt, Caltech-JPL

    All the fundamental forces of the universe are known to follow the laws of quantum mechanics, save one: gravity. Finding a way to fit gravity into quantum mechanics would bring scientists a giant leap closer to a “theory of everything” that could entirely explain the workings of the cosmos from first principles. A crucial first step in this quest to know whether gravity is quantum is to detect the long-postulated elementary particle of gravity, the graviton. In search of the graviton, physicists are now turning to experiments involving microscopic superconductors, free-falling crystals and the afterglow of the big bang.

    Quantum mechanics suggests everything is made of quanta, or packets of energy, that can behave like both a particle and a wave—for instance, quanta of light are called photons. Detecting gravitons, the hypothetical quanta of gravity, would prove gravity is quantum. The problem is that gravity is extraordinarily weak. To directly observe the minuscule effects a graviton would have on matter, physicist Freeman Dyson famously noted, a graviton detector would have to be so massive that it collapses on itself to form a black hole.

    “One of the issues with theories of quantum gravity is that their predictions are usually nearly impossible to experimentally test,” says quantum physicist Richard Norte of Delft University of Technology in the Netherlands. “This is the main reason why there exist so many competing theories and why we haven’t been successful in understanding how it actually works.”

    In 2015 [Physical Review Letters], however, theoretical physicist James Quach, now at the University of Adelaide in Australia, suggested a way to detect gravitons by taking advantage of their quantum nature. Quantum mechanics suggests the universe is inherently fuzzy—for instance, one can never absolutely know a particle’s position and momentum at the same time. One consequence of this uncertainty is that a vacuum is never completely empty, but instead buzzes with a “quantum foam” of so-called virtual particles that constantly pop in and out of existence. These ghostly entities may be any kind of quanta, including gravitons.

    Decades ago, scientists found that virtual particles can generate detectable forces. For example, the Casimir effect is the attraction or repulsion seen between two mirrors placed close together in vacuum. These reflective surfaces move due to the force generated by virtual photons winking in and out of existence. Previous research suggested that superconductors might reflect gravitons more strongly than normal matter, so Quach calculated that looking for interactions between two thin superconducting sheets in vacuum could reveal a gravitational Casimir effect. The resulting force could be roughly 10 times stronger than that expected from the standard virtual-photon-based Casimir effect.

    Recently, Norte and his colleagues developed a microchip to perform this experiment. This chip held two microscopic aluminum-coated plates that were cooled almost to absolute zero so that they became superconducting. One plate was attached to a movable mirror, and a laser was fired at that mirror. If the plates moved because of a gravitational Casimir effect, the frequency of light reflecting off the mirror would measurably shift. As detailed online July 20 in Physical Review Letters, the scientists failed to see any gravitational Casimir effect. This null result does not necessarily rule out the existence of gravitons—and thus gravity’s quantum nature. Rather, it may simply mean that gravitons do not interact with superconductors as strongly as prior work estimated, says quantum physicist and Nobel laureate Frank Wilczek of the Massachusets Institute of Technology, who did not participate in this study and was unsurprised by its null results. Even so, Quach says, this “was a courageous attempt to detect gravitons.”

    Although Norte’s microchip did not discover whether gravity is quantum, other scientists are pursuing a variety of approaches to find gravitational quantum effects. For example, in 2017 two independent studies suggested that if gravity is quantum it could generate a link known as “entanglement” between particles, so that one particle instantaneously influences another no matter where either is located in the cosmos. A tabletop experiment using laser beams and microscopic diamonds might help search for such gravity-based entanglement. The crystals would be kept in a vacuum to avoid collisions with atoms, so they would interact with one another through gravity alone. Scientists would let these diamonds fall at the same time, and if gravity is quantum the gravitational pull each crystal exerts on the other could entangle them together.

    The researchers would seek out entanglement by shining lasers into each diamond’s heart after the drop. If particles in the crystals’ centers spin one way, they would fluoresce, but they would not if they spin the other way. If the spins in both crystals are in sync more often than chance would predict, this would suggest entanglement. “Experimentalists all over the world are curious to take the challenge up,” says quantum gravity researcher Anupam Mazumdar of the University of Groningen in the Netherlands, co-author of one of the entanglement studies.

    Another strategy to find evidence for quantum gravity is to look at the cosmic microwave background [CMB] radiation, the faint afterglow of the big bang, says cosmologist Alan Guth of M.I.T.

    Cosmic Background Radiation per ESA/Planck

    ESA/Planck 2009 to 2013

    Quanta such as gravitons fluctuate like waves, and the shortest wavelengths would have the most intense fluctuations. When the cosmos expanded staggeringly in size within a sliver of a second after the big bang, according to Guth’s widely supported cosmological model known as inflation, these short wavelengths would have stretched to longer scales across the universe.


    Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    Alan Guth’s notes:

    This evidence of quantum gravity could be visible as swirls in the polarization, or alignment, of photons from the cosmic microwave background radiation.

    However, the intensity of these patterns of swirls, known as B-modes, depends very much on the exact energy and timing of inflation. “Some versions of inflation predict that these B-modes should be found soon, while other versions predict that the B-modes are so weak that there will never be any hope of detecting them,” Guth says. “But if they are found, and the properties match the expectations from inflation, it would be very strong evidence that gravity is quantized.”

    One more way to find out whether gravity is quantum is to look directly for quantum fluctuations in gravitational waves, which are thought to be made up of gravitons that were generated shortly after the big bang. The Laser Interferometer Gravitational-Wave Observatory (LIGO) first detected gravitational waves in 2016, but it is not sensitive enough to detect the fluctuating gravitational waves in the early universe that inflation stretched to cosmic scales, Guth says.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    A gravitational-wave observatory in space, such as the Laser Interferometer Space Antenna (eLISA, just above), could potentially detect these waves, Wilczek adds.

    In a paper recently accepted by the journal Classical and Quantum Gravity, however, astrophysicist Richard Lieu of the University of Alabama, Huntsville, argues that LIGO should already have detected gravitons if they carry as much energy as some current models of particle physics suggest. It might be that the graviton just packs less energy than expected, but Lieu suggests it might also mean the graviton does not exist. “If the graviton does not exist at all, it will be good news to most physicists, since we have been having such a horrid time in developing a theory of quantum gravity,” Lieu says.

    Still, devising theories that eliminate the graviton may be no easier than devising theories that keep it. “From a theoretical point of view, it is very hard to imagine how gravity could avoid being quantized,” Guth says. “I am not aware of any sensible theory of how classical gravity could interact with quantum matter, and I can’t imagine how such a theory might work.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 11:28 am on July 23, 2018 Permalink | Reply
    Tags: , , , , Did a Stellar Intruder Deform Our Outer Solar System?, , Scientific American, Sedna   

    From Scientific American: “Did a Stellar Intruder Deform Our Outer Solar System?” 

    Scientific American

    From Scientific American

    July 23, 2018
    Shannon Hall

    New results suggest a massive star once swung dangerously close to our sun—helping to shape the mysterious features we see today.

    The odd orbit of the dwarf planet Sedna (shown here in an artist’s conceptualization) and other outer solar system objects suggests a visiting star may have swerved too close to the sun long ago. Credit: NASA and JPL-Caltech

    There is a mystery brewing in the far reaches of our solar system.

    Astronomers have long thought the eight planets orbit in nearly perfect circles because they once formed within the swirling disk of dust and gas that surrounded the young sun. But in 2003 scientists discovered something strange: a dwarf planet known as Sedna whose elongated orbit takes it from twice Pluto’s distance to more than 20 times its distance from the sun. And it is not alone. In the years since astronomers have uncovered nearly two dozen distant icy objects whose orbits are oblong and strangely tilted compared to the plane of the solar system. To explain such oddities, scientists speculated that maybe these worlds are scars from a violent past, a sign something—perhaps a passing star—knocked them off course in our solar system’s infancy. Or maybe there is a distant ninth planet whose gravity sculpts their peculiar orbits.

    The latter hypothesis has gained traction over the past several years, leaving the first in the dust, says Susanne Pfalzner, an astronomer at the Max Planck Institute for Radio Astronomy in Germany. Anomalies in the orbits of some small outer solar system objects have amassed evidence for a “Planet Nine” roughly 10 times Earth’s mass. Meanwhile a stellar interloper has been considered too unlikely—until now. Pfalzner and her colleagues recently published a paper to the preprint server arXiv that has been accepted by The Astrophysical Journal showing stars might buzz our solar system far more often than previously thought. Not only do the results lend credibility to a stellar flyby but they just might also explain how the elusive Planet Nine would have landed in its odd orbit in the first place.

    Effect of a prograde, parabolic fly-by of a star with a) M=0.5 M, b) M2= 1, Mand c) M2= 5 Mthat is inclined by 60 degree and has a angle of periastron equal zero. The perihelion distance is always chosen in such a way as to lead to a 30-35 AU disc. The top row indicates the eccentricity distribution of the matter with a central area of most particles on circular orbits and more eccentric orbits at larger distances form the Sun. The eccentricities are indicated by the different colours given in the bar. The origin of the different eccentricity populations in the original disc can be seen in bottom row, where matter indicated in grey becomes unbound from the Sun. Note that in c) the path of the perturber is not visible because it is outside the shown frame. Credit: arXiv:1807.02960 [astro-ph.GA]

    Astronomers know the sun has not always been so solitary. It was born within a cluster of hundreds to perhaps tens of thousands of stars that dispersed only 10 million years later. So while the sun was still entombed within that cluster, stars would have rocked to and fro in a dizzying dance that easily could have brought one waltzing into our nascent solar system. But after the cluster broke apart the likelihood of such an encounter dropped nearly to zero, or so the thinking went. But Pfalzner and her colleagues now argue the odds of an encounter remained quite high after the cluster had started to disperse. After many long computer simulations they found there is a 20 to 30 percent chance a star perhaps as massive as the sun would swing nearly as close as Pluto at 50 to 150 astronomical units. (One AU is the mean distance from Earth to the sun, or 93 million miles.) And there is no doubt such a close approach would surely shake our young solar system.

    Although the large planets would remain unbothered (much like the sun is only slightly jostled by the minor gravities of the eight planets), the encounter would perturb the solar system’s smaller objects—tossing them around and placing them in odd orbits in the distant reaches of the solar system. What is more: the simulations also re-created a second trend astronomers have observed in the solar system, that outer objects tend to cluster together in space. They travel together in tight-knit groups that all cross the plane of the solar system at roughly the same spot before swinging outward to the same distant point. In short, simulations including a stellar interloper can perfectly re-create the observations to date. “But whether they’ll last for 4.5 billion years” or over the solar system’s entire life span, “is the million-dollar question,” says Scott Kenyon, an astronomer at Harvard–Smithsonian Center for Astrophysics who was not involved in the research. And Pfalzner agrees. She would like to model the long-term behavior next to see whether those changes will hold over the solar system’s entire lifetime. It could be that a flyby clusters objects for a cosmic moment before they randomize again. If that is the case, then a planet is the best explanation for the observations.

    Scientists are eagerly tracking down more data with a number of different observing campaigns. A handful of teams, for example, are already scouring large chunks of the heavens in search of more oddities in the outer solar system. Scott Sheppard, an astronomer at the Carnegie Institution for Science who was not involved in the study, cannot contain his excitement over the upcoming Large Synoptic Survey Telescope—an 8.4-meter-wide scope that will likely uncover hundreds of new solar system rocks.


    LSST Camera, built at SLAC

    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    “That’s really going to open up the floodgates for trying to discover these distant objects,” he says.

    Meanwhile Kenyon is hopeful the Gaia spacecraft, which is in the process of charting one billion stars to unprecedented accuracy, will help find our sun’s long-lost siblings.

    ESA/GAIA satellite

    That will allow scientists to better understand the stellar cluster in which our young solar system formed, along with the likelihood another star zoomed too close. “Gaia is the new savior on the block,” he says. A recent Gaia study even traced the paths of nearby stars into the past and projected those paths into the future, only to find that 25 stars speed dangerously close to home over a 10-million-year time period. That tally is seven times as much nearby stellar traffic as previously thought. Then, of course, there are a number of surveys searching for the elusive Planet Nine itself.

    But Pfalzner argues the discovery of another major member of the solar system will not rule out a stellar flyby. “It’s not an either–or scenario,” she says. “If Planet Nine exists, this would not be in any way a contradiction to the flyby model, but possibly even a point in favor for it.” Her team argues Planet Nine’s predicted orbit, which is also both eccentric (stretched out) and inclined (tilted from the solar system’s plane), was likely shaped by the stellar interloper itself. So she and others will continue to hunt for both Planet Nine and further oddities.

    And although astronomers might disagree over the specifics of our solar system’s origin story, they are all certain the treasure trove of objects already discovered in the outer solar system is only the beginning. Sedna was the tip of the iceberg, Sheppard says. “There’s just so much sky we haven’t covered to date that it’s more likely than not there’s something pretty big out there.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 8:15 pm on March 22, 2018 Permalink | Reply
    Tags: , , , New England Is Sitting on a Bed of Hot Rocks, , Scientific American   

    From Rutgers via Scientific American: “New England Is Sitting on a Bed of Hot Rocks” 

    Rutgers smaller
    Our once and future Great Seal.

    Rutgers University

    Scientific American

    April 2018
    Shannon Hall

    Colorful forests fill the landscape in the Berkshires of western Massachusetts.
    Photograph by Berthold Steinhilber, laif, Redux, courtesy of natgeo.com, which also provided the link to the article in Geology, which Scientific American was to lazy to do. Looking for the link is how I found the photo.

    Credit: Thomas Fuchs

    For the past 200 million years New England has been a place without intense geologic change. With few exceptions, there have been no rumbling volcanoes or major earthquakes. But it might be on the verge of awakening.

    Findings published this January in Geology show a bubble of hot rock rising underneath the northern Appalachian Mountains. The feature was first detected in 2016 by EarthScope, a collection of thousands of seismic instruments sprinkled throughout the U.S. Vadim Levin, a geophysicist at Rutgers University, says this wealth of sensors lets earth scientists peer under the North American continent, just as the Hubble Space Telescope has enabled astronomers to gaze deep into the night sky. Should the broiling rock breach the surface—which could happen, though not until tens of millions of years from now—it would transform New England into a burbling volcanic landscape.

    The finding has sparked many questions, given that New England is not located along an active plate margin (where one tectonic plate rubs against another) but sits squarely in the middle of the North American plate. The exact source of the hot rock bubble, for example, is unclear. Because the edge of the North American continent is colder than a plate near an active margin, Levin suspects this edge is cooling the mantle—the layer just below the crust that extends toward the earth’s core. As cold chunks of mantle sink, they may displace hotter segments, which would rise toward the surface. Scientists believe they have now imaged such an ascending piece. Although it sounds simple, this scenario “is a story that at present does not have a place in a textbook,” Levin says.

    Or perhaps pieces of the North American continent are breaking off and sinking into the mantle (which would also push the warmer mantle upward), observes William Menke, a geophysicist at Columbia University, who was not part of the study.

    Scientists do not yet know which model is correct or if an entirely different one may be involved. Levin and his colleagues are eager to collect more data to bring this unusual hotspot into sharper focus and, in doing so, flesh out the theory of plate tectonics. “We know little about the interior of our planet, and every time we look with a new light … we find things we did not expect,” Levin says. “When we do, we need to rethink our understanding of how the planet functions.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

    Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

    As a ’67 graduate of University college, second in my class, I am proud to be a member of

    Alpha Sigma Lamda, National Honor Society of non-tradional students.

  • richardmitnick 1:37 pm on October 9, 2017 Permalink | Reply
    Tags: Anxiety may seem to be a prominent feature of autism but it is not one of the diagnostic criteria, , Autism and Anxiety, Children with autism may be inherently more likely to develop anxiety than their typical peers, Scientific American, Why a fear of the unknown is a strong feature of autism is less clear   

    From SA: “Unmasking Anxiety in Autism” 

    Scientific American

    Scientific American

    October 9, 2017
    Jessica Wright

    Anxiety can assume unusual forms—turning uncertainty, or even a striped couch, into a constant worry.

    Credit: Corey Brickley, Spectrum.

    No one except Gregory Kapothanasis knows exactly what upset him today. On this hot day in July, he went to his day program for adults with developmental disabilities, as he has done without incident five days a week for the past four years. But then things unraveled. According to the program’s report, he grabbed a staff member’s arm hard enough to bruise it. Then, on the bus during the daily outing, he started screaming and hitting his seat. Now, several hours later, he is finally home, but there is a stranger in his living room. Bouncing from one couch to another, clutching a faded beige blanket stolen from his aunt’s dog, Kapothanasis still seems out of sorts.

    His mother, Irene — who has cared for him, with the help of home aides, for all of his 24 years — is playing over the day’s events, trying to figure out what triggered him. His outburst is disturbingly reminiscent of a difficult period that peaked six years ago but is uncharacteristic of the young man today. Kapothanasis loves interacting with other people, going to the beach and dining at DiMillo’s, a floating restaurant in a decommissioned car ferry in Portland, Maine.

    Kapothanasis has autism and speaks only a few words: He can’t explain what happened this morning. Did he have constipation and discomfort, as his doctor suggested? Did he get bored of the day’s program, causing him to act out? Had something occurred on the bus previously that made him fear that part of his day? All his mother can do is wonder — and try to make his evening better.

    Kapothanasis places several pieces of gum in his mouth, something his mother says soothes him. Then he curls up for a nap and dozes off. The time it takes him to calm down is short compared with the protracted meltdowns that routinely overtook him during his teen years. He became aggressive starting in puberty: He would bite and hit himself, or hit and grab other students, teachers and bus drivers. His mother had to supervise his interactions with his siblings, even though, as triplets, they had always been close. In December 2011, when he was 18 years old and over 6 feet tall, his behaviors had escalated so much that his school enrolled him at the inpatient clinic at Spring Harbor Hospital in Maine.

    “Look, we all have scars from Gregory, we’ve all felt his wrath. And it came to the point where he had to be institutionalized,” his mother says. He spent five long weeks at the hospital. “It was probably one of the darkest moments in our lives,” she says.

    When Kapothanasis arrived at the hospital, he didn’t seem sad, cried only on occasion and didn’t respond to things not visible to others — signs he did not have depression or psychosis. But he startled easily, paced and rocked in place, and sweated heavily. “The phrase ‘cat on a hot tin roof’ was pretty descriptive,” recalls Matthew Siegel, director of the developmental disorders program at the hospital.

    After several weeks of close observation, Siegel and his colleagues managed to piece together Kapothanasis’ behaviors into a clear diagnosis, based on criteria outlined in the “Diagnostic and Statistical Manual of Mental Disorders.” In addition to his autism, “he was kind of screaming anxiety — if you’re looking for it,” Siegel says. Until then, it seems no one had been. When Kapothanasis entered the clinic, he was on his third antipsychotic medication. Some are approved to treat aggression as a feature of autism, but none treat anxiety. “It’s fair to say that he was not being treated for anxiety,” Siegel says.

    There are many reasons it took nearly six years for Kapothanasis to get the help he needed. Doctors may have assumed that his aggression and tendency to hurt himself were part of his autism, Siegel says. Traits that characterize autism — including social deficits, stereotyped movements and restricted interests — can mask or mimic symptoms of anxiety. During a visit to an outpatient clinic, for example, Siegel points out a nonverbal young woman with autism who repeatedly traces a pattern in the air with her hands. At first glance, her gestures resemble ‘stimming,’ the repetitive behaviors often seen in autism. But she does it at specific times, Siegel says, suggesting a ritual related to obsessive-compulsive disorder — a form of anxiety.

    Compounding the problem, many people on the spectrum, like Kapothanasis, cannot tell their caregivers or doctors what they are feeling or thinking. Those who can may still struggle to identify and understand their own emotions — a phenomenon called alexithymia — or to articulate them to others. Because of these factors, the clinical questionnaires designed to ferret out anxiety traits in neurotypical individuals are woefully inadequate for many people with autism. The tests may also miss children with autism, who can have unusual phobias, such as a fear of striped couches or exposed pipes.

    “People on the spectrum have really unique, distinct ways of perceiving the world, and also have distinct experiences, which is why we’ll see classic things like social phobia and generalized anxiety, but also maybe these more distinct, more autism-related manifestations,” says psychologist Connor Kerns, assistant research professor at the A.J. Drexel Autism Institute in Philadelphia. Kerns and others are working on new ways to measure both ordinary and unusual forms of anxiety in people with autism. This work could help clinicians better detect the anxiety that hides behind autism, reveal the underlying mechanisms and lead to better treatment.

    Hiding in plain sight:

    Anxiety may seem to be a prominent feature of autism, but it is not one of the diagnostic criteria. “People say, ‘Oh, it’s just part of autism, everyone with autism has anxiety.’ That is 100 percent not true,” Siegel says. “I’ve got 12 kids sitting outside my door at my hospital right now, and several of them do not have anxiety.”

    Studies attempting to pin down the proportion of people with autism who also have clinically significant anxiety have produced a staggeringly broad range, from 11 to 84 percent. The discrepancy in these reported rates is “fundamentally unbelievable,” says Lawrence Scahill, professor of pediatrics at Emory University in Atlanta. “Whenever you see a range like that, you know that it’s driven by the source of the sample, where they got the sample from, the methods used to do the assessment and how quick they were to pull the trigger on a diagnosis.”

    What is believable, he says, is that autism and anxiety are not independent conditions that sometimes co-occur. In fact, children with autism may be inherently more likely to develop anxiety than their typical peers. But the overlap in features between the two conditions makes diagnosing anxiety extremely difficult. “I’m convinced that the measurement of anxiety in children with autism has to be different,” Scahill says.

    The traditional tests for anxiety, such as the Screen for Child Anxiety-Related Emotional Disorders and the Spence Children’s Anxiety Scale, rarely hold up as well in children with autism as they do in the groups they were designed for. In a 2013 study, Scahill and his colleagues investigated one particular test — the 20-item anxiety scale of the Child and Adolescent Symptom Inventory (CASI) — in parents of 415 children with autism.

    How the researchers framed the test’s questions significantly affected how the parents responded. Less than 5 percent of the parents endorsed statements describing anxiety that require a child to express herself — for instance, “worries about physical health” or “complains about feeling sick when separation is expected.” By contrast, parents were most likely to agree with statements that rely on their observations, such as “acts restless or edgy.” This trend was especially true among parents whose children have intellectual disability.

    Based on their findings, Scahill and his colleagues decided to talk to parents as part of their efforts to develop a measure of anxiety specific to children with autism. Over the course of six focus groups, which yielded more than 600 pages of transcripts, the researchers interviewed the parents of 45 children who have both autism and anxiety. They encouraged the parents to describe their child’s behaviors rather than make inferences about what the child was thinking. They then used these observations to formulate 52 questions. The trick to deciding which questions to ask, Scahill says, was not letting features of autism “leak” into them. Many parents talked about meltdowns but, when pressed for more detail, agreed they couldn’t tell the difference between meltdowns caused by anxiety and those that crop up for other reasons related to autism. Using meltdowns to flag anxiety in children with autism would have been a mistake, Scahill says. Instead, the focus group responses pointed to new indicators, including “Gets stuck on what might go wrong” and “Needs a lot of reassurance that things will work out.”

    Credit: Spectrum

    In unpublished data, the researchers combined the 52 new questions with the 20 questions on the CASI and gave them to 990 parents of children with autism. Based on the responses, they weeded out 31 items that were either redundant, seemingly irrelevant or rarely endorsed by the parents. Based on the remaining 41 queries, they found that roughly one-quarter of the children in the study have high levels of anxiety, another quarter have low levels of anxiety, and the rest fall somewhere in between.

    The researchers plan to test whether the measure is reliable over time, evaluating the same children with 10-day breaks between sessions. If the screen proves reliable, Scahill says, it might also be used to assess the efficacy of anxiety treatments in children with autism. “We have more to offer the treatment of anxiety right now than we have for the core features of autism,” he says. “So it behooves us, in my opinion, to be tough-minded about making sure we’re measuring anxiety and not something else.”

    Into the unknown:

    Erik Chaston, a 29-year-old graduate of Brigham Young University in Provo, Utah, works at a credit union, developing detailed workflows for the bank’s employees. Chaston, who has autism, has won awards for his clear and surprisingly entertaining videos that elucidate the supply-chain process. But for years, he was also fixated on the faint clicking noises people make with their saliva when they talk.

    As a student, while working as a sound engineer for the campus sports channel, Chaston began obsessing over fixing these and other sounds in his recordings. “It made me feel like I was constantly worried about things, because everyone talks like this,” he says. He held it together and excelled at work, but would shut down around his family. After he graduated, the problem seeded fears about what kind of job he would be able to hold down. The uncertainty made him especially anxious, he recalls.

    This intolerance of uncertainty is a common refrain among people with autism and their parents. For many people on the spectrum, this feeling may simply be an expression of one of autism’s core features — for instance, it may relate to inflexibility in the need to have enough time for a special interest or a fixation. But if that fixation turns into a source of constant fear or worry, it may in fact be an expression of anxiety, researchers say. “To me, it makes a lot of sense that it’s something about the sticky element of the brains of people on the spectrum that would also lead them to have anxiety about change,” Kerns says.

    In 2014, Kerns and her colleagues developed an adapted version of the Anxiety Disorders Interview Schedule (ADIS) — a one- to two-hour clinical interview with both parents and children, designed to flag anxiety. Based on interviews with 59 children who have autism and their parents, the researchers documented examples of anxiety that don’t fit the standard definition. Although nearly half of the children had traditional forms of anxiety, 18 of them also showed signs of non-traditional anxiety; another 9 children showed only the unusual forms of anxiety, such as an intolerance of uncertainty.

    So Kerns and her colleagues expanded their ‘ASD-specific addendum’ to flag non-traditional anxiety traits that the standard screen might miss: fear of novelty or uncertainty; fear of social situations for reasons other than social ridicule; excessive worry about being able to engage in a special interest; and unusual phobias. The section on fearing change asks, for example, “Does your child react if the change is positive (e.g., getting out of school early)?” The addendum also includes questions about a child’s social skills, sensory sensitivities and repetitive behaviors to help clinicians differentiate anxiety from autism features. For instance, it asks about a child’s history with bullying or social rejection to clarify whether a child is avoiding social events for a good reason — because her bully might attend — or because she is so traumatized by bullying that she fears any social outing. Only the latter would qualify as anxiety. “We want to look for when anxiety has overgrown the actual threat,” Kerns says. Her work solidifies what many clinicians knew anecdotally. “[Kerns] put a description to something that we had been seeing but didn’t have a word for,” Siegel says.

    Why a fear of the unknown is a strong feature of autism is less clear. Some researchers speculate that people with autism have trouble predicting future events, heightening their sense of uncertainty. Other work implicates sensory sensitivities and poor verbal comprehension, suggesting that different aspects of autism feed into this type of anxiety.

    Scientists are also looking for less subjective ways to measure anxiety in autism using various physiological and brain-imaging methods. John Herrington at the Children’s Hospital of Philadelphia and his colleagues are in the midst of a long-term study of 150 children, roughly half of whom have autism, looking at measures of stress, such as heart rate variability and sweat levels. They are also using a technology that tracks where someone is looking to try to distinguish a lack of social interest from social anxiety. Initial findings from their brain-imaging data suggest that the amygdala, a brain region involved in making fearful associations, is smaller in children with autism and anxiety than in those with autism alone.

    Another team is also homing in on the amygdala. Mikle South’s team at Brigham Young University is exploring the theory that instead of having an overactive fear response, people with autism have trouble finding a ‘safe space’ and, as a result, are afraid of everything. To test that idea, he is interviewing some adults with autism about their specific fears and scanning others’ brains. More than half of the people he talks to are consumed with worry, he says. “They worry about so much all of the time, they worry about everything,” South says. “There’s nothing they’re not worrying about.”

    Confronting fears:

    Breaking the cycle of fear is never easy, but it may be especially difficult for someone with autism. For Chaston, help came from what he considered an unexpected source — a self-help book on mindfulness that his mother foisted on him. Practicing mindfulness helped him develop strategies to deal with things that annoyed him. The best-documented approach for treating anxiety in children with autism, cognitive behavioral therapy (CBT), works on similar principles. CBT combines talk therapy with repeated exposures to the source of the fear to change unhelpful thought patterns and behaviors.

    That said, many children with autism may not benefit from traditional forms of CBT, says Eric Storch, professor of psychology at the University of South Florida in Tampa. Storch’s team has found that children with autism who benefit from CBT do not always maintain those gains: Those who improve only a little sometimes do much better one to two years later, whereas some of those who respond well later relapse. “It wasn’t sticking the way we would predict,” Storch says. The findings suggest that children with autism need therapy for longer, and with more follow-up, than their typical peers — “a critical difference in the treatment approach,” he says.

    Children with autism also have trouble generalizing lessons learned in therapy to other aspects of their lives. That means it is especially important to include their caregivers in treatment, because these adults can reinforce the lessons throughout the child’s day, Storch says.

    Credit: Spectrum

    To incorporate some of this extra support, a team at the University of California, Los Angeles developed a modified version of CBT, called the Behavioral Interventions for Children with Autism. The revision recommends, for example, that doctors and parents help a child to master appropriate social behaviors before putting the child in a feared social situation. Confronting situations that make the child anxious is crucial to the therapy’s success, Storch says. The modification also offers extra help for children who may feel socially isolated, having therapists work with schools to give these children peers who can guide them through social situations.

    A small 2009 trial suggested that anxiety levels in most children with autism abate after they receive this modified version of CBT. A follow-up analysis found that another version of CBT adjusted for adolescents with autism is just as effective. A team of researchers, including Storch and Kerns, plans to compare the modified version with other therapies in children with autism in a 16-week trial of 180 children. Children who have autism and clinically diagnosed anxiety will receive either the modified or the traditional form of CBT, or will continue with whatever treatment they received before.

    Their parents will also take the ADIS, along with Kerns’ addendum. It is possible that the children who have non-traditional anxiety will benefit the most from a modified treatment, Kerns says.

    However successful, CBT cannot be the only option for children with autism, notes Roma Vasa, a child and adolescent psychiatrist at the Kennedy Krieger Institute in Baltimore. “There’s a lot of variability in how much they can really report on their internal experience and how connected they are with their thoughts and their feelings,” she says. “There needs to be more trials of effective medication to help these kids.”

    There are no drugs approved for treating anxiety in autism. Last year, Vasa and her colleagues published a set of recommendations for clinicians who prescribe anxiety drugs to children on the spectrum. Among her guidelines: Raise doses slowly, as these drugs may exacerbate irritability.

    In Kapothanasis’ case, drugs to treat his anxiety, including fluoxetine and guanfacine, turned out to be extremely helpful. Still, Siegel’s team didn’t rely on medications alone to treat him. They discovered that Kapothanasis had no real means of communicating. His aides at school had told his mother that he could, for example, ask for a bottle of water by handing over a drawing of it. But the speech-language pathologists in the hospital realized he really had no idea how to use this picture-exchange system. They helped him learn a new system, in which he points to photos of things from his daily life rather than to cartoon depictions of them. They prepared a visual schedule that lets him know what to expect each day. And, perhaps most valuable, according to his mother, is that they found new ways for him to soothe himself: by bouncing on a yoga ball or running his hands through tubs of uncooked rice.

    These tactics are ones that now, years later, can still turn a bad day around. When Kapothanasis wakes from his catnap, he ambles over to the kitchen and makes himself a snack. Back in the living room, he spots a blue fleece blanket his mother has laid out for him in front of the television, a plastic bowl filled with uncooked rice in the center.

    As he walks over to the rice, the tension in the air thins palpably. Contorting his large body into a pretzel shape and leaning close to the blanket, Kapothanasis dumps out the container’s contents. Then, carefully placing the bowl in front of him, he scoops up handfuls of rice and lets them fall through his fingers in soft streams down his forehead. The grains tap out a staccato beat as they land in the bowl. Once it is full, he empties the bowl and begins again. And again … and again. After a while, he looks up, faces the stranger in the room for the first time. And smiles.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 12:22 pm on December 29, 2016 Permalink | Reply
    Tags: , , CAR-T therapy, , Scientific American   

    From SA: “Experimental Cancer Therapy Makes Inroads Treating Brain Cancer” 

    Scientific American

    Scientific American

    December 29, 2016
    Meghana Keshavan

    The immunotherapy approach may soon be commercially available for leukemia and lymphoma.

    Credit: Akira Ohgaki Flickr (CC BY 2.0)

    Glioblastoma is one of the deadliest cancers — an illness that responds to few treatment options, and often poorly. But a single case study that uses an experimental immunotherapy to treat these brain tumors might give oncologists a new way to approach the disease.

    The therapy, called CAR-T, is controversial and has faced hurdles in clinical trials. It has shown great promise in treating blood cancers like leukemia and lymphoma — but has proven challenging in treating other forms of the disease, including solid tumors.

    “This is the first example of CAR-T working in solid tumor cancers,” said Dr. Behnam Badie, chief of neurosurgery at City of Hope and a key investigator in the study. “In the initial treatments, I was holding my breath, waiting to get called in the middle of the night to go rescue somebody. But it’s amazing how safe it was.”

    The results are being published this week in the New England Journal of Medicine.

    Researchers at the City of Hope cancer treatment center in the Los Angeles Area tested a CAR-T therapy out on a 50-year-old man with recurrent multifocal glioblastoma — that is, several tumors growing in tandem in his brain. He had failed all other available treatments.

    CAR-T therapy involves extracting a patient’s immune cells, re-engineering them to learn how to target their cancer, and then feeding them back into the body. Surgeons removed the tumors, and then infused the experimental cellular therapy directly to the regions where the cancer had grown (other CAR-T treatment protocols are usually intravenous).

    The patient was in remission for about seven months after the CAR-T infusions began. The tumors did come back — but not in the areas that responded to the T cells, Badie said.

    This experimental therapy may soon be available commercially for certain blood cancers, as two drug makers — Novartis and Kite Pharma — are on the verge of filing for approval with the Food and Drug Administration.

    The glioblastoma therapy targets cells with the IL-13Rα2 antigen, a receptor which is found commonly on cells in brain tumors. City of Hope researchers are testing out a number of other antigens specific to brain cancers, Badie said, though they’re not disclosing which.

    Notably, the treatment was fairly innocuous, Badie said, which was certainly unexpected, since CAR-T therapy is notorious for its adverse events. In particular, Badie said he was bracing himself for neurotoxicity:

    “The results were really dramatic,” Badie said. “My own father passed from glioblastoma 10 years ago — and I never imagined we’d get to this stage so fast.”

    There have been other trials studying CAR-T’s efficacy in glioblastoma, but with intravenous application. The results from this one patient, Badie said, were good initial evidence that delivering CAR-T to the tumor site itself, rather than intravenously, might enhance efficacy. Badie said he believes that, based on this study, CAR-T could prove to be potent in other solid tumor cancers — particularly pediatric brain cancers.

    The results spurred both cautious optimism — and a dose of skepticism.

    “I can’t say this paper’s solved the problem of solid tumors, or this is the way to treat them,” said Dr. Jae Park, a hematologist-oncologist who specializes in CAR-T therapy at Memorial Sloan Kettering Cancer Center. “But it’s the first trial to show an objective response in glioblastoma, and suggests this is one way to get around the limitations of CAR-T.”

    But it’s a “flash in the pan,” according to Dr. Vinay Prasad, a hematologist-oncologist at the Oregon Health and Sciences University.

    “Even though this was a provocative case, even in this one case the cancer has already returned,” Prasad said in an email. “Will CAR-T work for other patients? Will it help most patients? Will it be better than alternatives? And will patients live longer or live better? We don’t know.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 11:51 am on December 29, 2016 Permalink | Reply
    Tags: , Are Giant Sequoia Trees Succumbing to Drought?, , Scientific American   

    From SA: “Are Giant Sequoia Trees Succumbing to Drought?” 

    Scientific American

    Scientific American

    Thayer Walker
    Video and Photographs by Novus Select

    Researchers climb 300 feet to the tops of thousand-year-old trees to analyze how they are faring.


    By the time John Muir and his trusty mule Brownie splashed across the Marble Fork of the Kaweah River in the fall of 1875, the Scottish-born naturalist had already seen his fair share of California grandiosity: Yosemite Valley; the high Sierra; Mariposa Grove. Muir had a thirst for exploration and a talent for storytelling. He founded the Sierra Club and dubbed its eponymous mountains the “Range of Light.” When Muir sauntered upon a montane plateau in what is now known as Sequoia National Park on that autumn day, he found a very large stand of very large trees. Drawing his poetry from the obvious he named it, quite simply, the Giant Forest.

    The dominant feature of the Giant Forest is the giant sequoia (Sequoiadendron giganteum), the biggest tree on Earth. Thousands of them grow in this 2,300-acre grove, including five of the ten largest specimens in the world. They reach heights of nearly 300 feet; their trunks can span more than 30 feet; and they’re nearly impossible to miss if you’re tromping beneath their canopy. “In every direction Sequoia ruled the woods…” Muir waxed in Our National Parks, “a magnificent growth of giants grouped in pure temple groves.” And yet, at 4:00 a.m. on a warm August morning, our hearty group of scientists and climbers is having a tough time finding the damn things.

    “I feel like we’ve gone too far,” says forest ecologist Wendy Baxter, 36, stopping the group. The ivory glow of a full moon offers enough illumination to hike without fear of face-planting, but it makes for a poor navigational beacon.

    It’s the fourth day of two weeks of fieldwork led by Baxter and fellow forest ecologist Anthony Ambrose. Scientists at UC Berkeley’s Dawson Research Lab, the two are part of Leaf to Landscape, a program in collaboration with the United States Geological Survey, the National Park Service, and the Carnegie Airborne Observatory, that is focused on studying and managing the health of the giant sequoias.

    California, of course, is in the middle of a historically punishing drought at a time when there’s never been more demand for water. According to the United States Forest Service, 62 million trees have died in California this year alone. Since 2011, a total of 102 million trees have perished, with tens of millions more on death’s doorstep. California’s forests generate fundamental ecosystem services by creating healthy watersheds, providing wildlife habitat, and sequestering atmospheric carbon, and they’re dying at unprecedented rates. Even the great giant sequoias are showing concerning signs of stress. It’s Ambrose and Baxter’s goal to collect and analyze tree samples to understand how the sequoias are faring under these rapidly changing conditions, and what might be done to protect them. But first we have to find them.

    “Have we come to any intersections at all?” asks Ambrose, 48, whose attention has been focused on answering my questions instead of spotting landmarks.

    “I remember this tree, for sure,” someone chirps, a sentiment that seems more appropriate as an epitaph on a lost hiker’s headstone than as a vote of directional confidence. After a brief parley, we correct our course up a gentle rise, down into a shallow basin, and past a pair of landmarks, unmistakable even at this dark hour.


    The path splits twin sylvan towers standing inches apart and hundreds of feet tall. It’s still too dark to marvel at their height, but the base of each tree inspires awe enough, gnarled and bulbous and swelling with woody knuckles the size of a Toyota Prius. A few hundred yards farther, the trail continues through the hollowed-out center of another sequoia. Fire, the great creator and destroyer, Kali of the Giant Forest, raged here long ago, burning out the tree’s core. The wound is enormous, 40 feet tall or more and nearly the size of the tree’s entire 12-foot diameter. Yet the grand monarch survived the blaze, which also would have cooked off the thick layers of duff that choke seedling growth, offering tiny sequoias a chance to one day touch the sky and survive their own infernos.

    The group splits apart at the meadow, each climber heading to the tree they’ll be sampling. The scientists have targeted 50 sequoias for study—“the biggest, gnarliest trees in the forest,” Ambrose says—and this morning he’ll climb a 241-footer. In most other forests a tree like this would be a star attraction with an honorific name and perhaps even a viewing area. Here, it’s simply known as “tree 271.”

    Ambrose has striking blue eyes and wears a woodsman’s beard with a chinstrap of white whiskers. He slides on his climbing harness and tugs the rope anchored to the crown some 24 stories above. He’s been studying trees for more than two decades, first with a focus on coast redwoods (Sequoia sempervirens) as an undergraduate and master’s student at Humboldt State University, and then on giant sequoias for his doctoral and post-doc work at Berkeley. “From an aesthetic perspective to a biological one, these trees are some of the most spectacular organisms on the planet,” he says with the enthusiasm of a boxing promoter. “They are the pinnacle of what a plant can become. They force you to think about life and your own place in it.”


    He clips on a pair of jumar ascenders—mechanical devices that attach to the rope and allow him to pull himself up. “You can’t really understand the true character of a tree from the ground,” he says. Ambrose turns off his headlamp, cranes his head toward the canopy, and begins the long, dark climb into a world of mystery.

    The giant sequoia has dominated its landscape for millions of years and captivated global imagination since the mid-19th century when rumors of trees the size of fairy-tale beanstalks came roaring out of the Sierras. One of three redwood species, the giant sequoia is not the world’s tallest tree; that crown belongs to its northern cousin, the coast redwood. But in terms of sheer volume of biomass, no living organism ever to walk, swim, fly, or stand on this planet comes close. They are of such stature that people struggle to describe them and so compare them to other very big things: blue whales, 747s, dinosaurs, the Statue of Liberty, elephant herds, space shuttles. Giant sequoias make mice of them all.

    More than 100 million years ago, when the planet was warmer and wetter, the sequoia’s earliest relatives thrived across much of the Northern Hemisphere. Redwood fossils have been found everywhere from Northern Mexico and the Canadian Arctic to England. During the late Miocene, some 10 to 20 million years ago, the closest direct ancestor of the giant sequoia lived in what is now southern Idaho and western Nevada. As the Sierra Nevada Mountain Range continued its uplift and the climate became drier, the giants’ range shrank. Today, the last remaining sequoias are limited to 75 groves scattered along a narrow belt of the western Sierra Nevada, some 15 miles wide by 250 miles long.


    Giant sequoias are among the longest-living organisms on Earth. Though no one knows the trees’ absolute expiry date, the oldest ever recorded is 3,200 years old. Muir claimed to have found a stump with 4,000 tree rings, one per year. During their early years the trees are subject to predation and the volatile whims of nature. Once they reach adolescence after a few centuries, however, sequoias become well-nigh indestructible. Their bark is soft and fibrous and contains very little pitch, qualities that make the trees extremely resistant to fire. The tannins that give their wood a rich cinnamon hue also repel insects and fungi.

    When a mature sequoia does die, mortality is usually a function of its marvelous size. Root rot can deprive a tree of a solid anchor and fire can undermine its base, but rarely will either actually kill a 30-story monarch. Gravity is the ultimate culprit, for a giant sequoia with an uncertain foundation faces a violent and certain end. The persistent tug of gravity can pull an unbalanced tree to the forest floor with such a thunderous crash that the reverberation can be heard miles away. The sequoia’s fate is an Icarian allegory, met not by flying too close to the sun, but by stretching too far from its roots.

    Thanks largely to their ability to withstand disease and drought, it’s extremely rare for a giant sequoia to die standing upright. “You don’t get to be 2,000 years old without surviving a few dry spells,” Ambrose tells me. Which is exactly why United States Geological Survey forest ecologist Nate Stephenson was so alarmed when, in September 2014, he went for a walk in the Giant Forest and saw something unexpected.

    “I had been saying with confidence for decades that if you hit a big drought, the first signs of climatic changes would show up in seedlings,” recalls Stephenson, who has studied trees in Sequoia and Kings Canyon National Parks since 1979. “I was completely wrong.”


    He surveyed an area that had burned a few years prior, where seedlings had taken root. Crawling around on his hands and knees, Stephenson was surprised to see that the seedlings were rigid and full of water, their leaves a vibrant blue-green. This was the third year of drought in California, and the summer of 2014 was particularly brutal. There should be some evidence of drought stress, he thought. Sitting on the ground, he leaned back, craned his head toward the heavens to ponder the mystery, and found his answer.

    Above him stood a grand old monarch. The crown of the tree was almost entirely brown, a scale of dieback he’d never seen. He searched for other trees displaying similar stress and when he found one with branches close to the ground, he touched it. The foliage crumbled off. In more than 30 years of studying these trees Stephenson had only seen two die on their feet. Five years into the current drought, he’s now seen dozens of standing dead.

    Stephenson quickly assembled a team to survey the 2014 dieback before autumn storms could blow away the evidence. The National Park Service (NPS) enlisted Ambrose and Baxter to begin their fieldwork in 2015. While the NPS and scientists working in Montana’s Glacier National Park might already be resigned to a glacier-free future as the climate changes, no one is ready to consider the possibility of Sequoia without its namesake trees.

    “Headache!!!” Ambrose yells.

    His warning, the tree-climbing vernacular for plummeting deadfall, fills the forest moments before a branch whooshes passed, inches from my head. It happens so quickly, the broken limb has already hit the ground before I have a chance to move.

    “And that’s why we wear helmets when we work around trees,” he explains to the small group of us standing at the base of the sequoia.

    The lessons come quickly on our first day of fieldwork. We set up on a steep hillside and Baxter demonstrates how to prepare the rigging for a climb. Tall and lean with a strong jawline and a soft voice, she’s as comfortable doing stable isotope analysis in the lab as she is setting a 600-foot static line in a tree. “I love the combination of physical exertion and intellectual stimulation,” she tells me. “It’s a struggle to get to the top of the tree. You’re sweating and huffing and puffing, but that’s when you start collecting your samples and the science begins.”

    In 2015, Baxter and Ambrose did much of the work themselves, identifying and rigging 50 trees, making six climbs a day, and collecting samples and measurements from each one. Their days began at 2:30 a.m. and ended at 10 p.m.—if they were lucky. “That was brutal,” Baxter recalls.

    They have more help this time around. Over the course of two weeks, more than a dozen volunteers—students, professional arborists, climbing junkies—will rotate in and out. The schedule, while not nearly as frantic as the previous year, is aggressive. We wake up at 3 a.m. and begin our hike from the Crescent Meadow parking lot into the Giant Forest an hour later. After climbing trees and taking and analyzing samples all day, we head back to our campground for some R&R before collapsing into bed.

    The immediate goal is to understand the severity of water stress the trees are facing, the water content in the leaves, and the amount of the stable carbon-13 (13C) isotope the tree uses during photosynthesis, which offers additional insight into how the trees are coping with drought. With that information, scientists and park officials can assess the trees’ health and begin to think about ways to protect giant sequoias through practices like controlled burns, which clear the ground for seedlings and eliminate less fire-resistant trees that compete for water.

    Ambrose’s first exposure to forest management came as a wildland firefighter following his senior year of high school in Chico, California. The experience, he recalls, involved “hours of boredom followed by long stretches of terror,” and gave him a first-hand look at how a policy of aggressive fire suppression can have an adverse effect on forest ecosystems.

    For more than a century, the government’s approach toward forest fire has been one of suppression. But indiscriminately stamping out frequent, less intense, naturally occurring fires disrupts the natural process of consumption and rejuvenation that species like giant sequoias need to thrive. It also allows dangerous levels of fuels to pile up—until one explosive holocaust vaporizes everything. “You get these large landscape conversions, conifer forests turning into brush,” Ambrose says.

    In 2013, the Rim Fire swept through the Sierras, consuming more than 257,000 acres. It was the third largest fire in California’s recorded history and burned for 15 months. It never reached Sequoia National Park, but it did sweep through parts of Yosemite some 100 miles north. As a precautionary measure, officials even set sprinklers around of some of Yosemite’s giant sequoias in case the fire got too close.

    Stretching hundreds of feet into the air presents some very real physical challenges for giant sequoias. See how these massive trees have overcome gravity to become giants of the forest.

    Giant sequoias, like all trees, play a central role in the hydrologic cycle. Storms drop rain and snow, which giant sequoias can chug to the tune of 800 gallons per day—more than any other tree. As the trees draw water out of the ground, the air surrounding the leaves draws water through the trees and, eventually, back into the atmosphere. That process, called transpiration, creates tension within the tree’s water columns. The drier the atmosphere and the less groundwater available, the higher the tension. Under extreme drought conditions, when that tension grows too high, those columns of water can snap like a rubber band. Gas bubbles form, creating an embolism that prevents the flow of water up the trunk. If this happens enough, a tree will shed its leaves and can, eventually, die.

    To measure water tension and other biological processes, climbers sample each tree twice a day, once under cool pre-dawn conditions when the tree is least stressed, and once under the heat of the midday sun. The scientists clip foliage from the lower and upper canopies, which allows them to assess conditions at different parts of the tree.

    After the safety talk and rigging demonstration, Ambrose grabs a laminated map from his pack and assigns the climbers to their trees. Pulling on a forest-green arborist harness, he clips a pouch onto each hip to carry his samples. Then he steps into the foot straps attached to the ascenders and begins the climb.

    His arms, legs, and core work in an assembly line of movement. Hanging on the rope in a crouch, he slides his right arm up, follows with his left, pulls his knees to his chest, and stands up straight in the stirrups, at which point he repeats the routine—scores of times on his way to the top. Climbers call it “jugging,” a process as onomatopoeically laborious as it sounds.

    About 100 feet up, Ambrose stops at the lower canopy, marked by the first significant limbs, which can grow up to six feet in diameter. He clips a handful of tiny branches, puts them into a plastic bag, shoves the bag into his hip pouch, and continues climbing. The tree’s leaves regulate gas exchange through tiny pores called stomata. The stomata take in carbon dioxide and release oxygen and water vapor. When a tree becomes too water-stressed it closes its stomata. This stops water loss through transpiration but also prevents the tree from absorbing atmospheric carbon dioxide and using it for photosynthesis. Sequoias have vast carbon stores to help them weather these lean times, but if the stomata stay closed for too long, the trees will eventually starve to death.

    As Ambrose works in the tree, I take a short hike up to the top of a hill just above the study site, where the cost of California’s drought reveals itself in spectacular panorama. The Middle Fork of the Kaweah River plummets from the high Sierra into the agricultural empire of the San Joaquin Valley. Polished granite swells and the jagged sawtooth mountains of the Great Western Divide dominate the horizon; pine, fir, and cedar trees blanket the river basin. The colors are rich and electric, but they don’t all sit right. In a sea of green, huge islands of red metastasize across the landscape. These ochre forests are not sequoia. They are thousands and thousands and thousands of dead trees.

    Numerically speaking, giant sequoias constitute a small portion of California’s forest. A few weeks before my foray with Ambrose and Baxter, I hopped on a survey flight with Greg Asner, principal investigator at the Carnegie Airborne Observatory (CAO), to get a better understanding of what’s happening to trees across the entire state and what that might indicate for the future of the sequoias.

    Asner, 48, runs a flying laboratory called the Airborne Taxonomic Mapping System, a Dornier 228 airplane tricked out with $12 million of custom-built equipment that allows the CAO to measure the composition, chemistry, and structure of a forest in detail and efficiency that, not long ago, was relegated to the realm of science fiction. “In California,” said Asner, “we have exact numbers on 888 million trees.”

    We met at 7:30 a.m. at Sacramento’s McClellan Air Park. Dressed in snappy black flight suits, Asner and his four-man team were going through last-minute checks and waiting for the sun to climb higher in the sky, which would allow for more accurate measurements. The goal for the day: map a 3,600-square-mile section of northern California forest.

    Collecting such voluminous amounts of detailed data requires a unique toolbox. The plane itself is geared toward special mission work with its high-payload capacity and short takeoff and landing capabilities. An imaging spectrometer, resting atop a hole cut in the belly of the plane, absorbs light across the spectrum, from ultraviolet to short-wave infrared. It allows the CAO to measure 23 different chemicals in the trees, including water, nitrogen, and sugar content. To work properly, internal sensors within the imaging spectrometer are kept at -132 Celsius, atomically cold temperatures.

    A laser system next to the imaging spectrometer fires a pair of lasers from the bottom of the plane 500,000 times per second, creating a three-dimensional image of the terrain below, and every tree on it. A second spectrometer, this one with an enhanced zoom capacity, allows the team to take measurements of individual branches on a tree—from 12,000 feet up. Finally, a piece of equipment known as an Internal Measurement Unit records the X,Y, and Z axes as well as pitch, roll, and yaw of the plane to ensure that its positioning in the air doesn’t compromise the accuracy of the data it collects from the ground. “This unit is the same technology as what’s in the nose of a cruise missile,” Asner explained. “Because of that, the State Department has a say in what countries we visit.” The CAO studies forests all over the world—Peru, Malaysia, Panama, South Africa, Hawaii.

    Once airborne, we dismissed the sprawl of the Central Valley for the coastal mountains. To the naked eye, the Shasta-Trinity National Forest looked splendorous, 2.2 million acres of rivers and mountains. Mount Shasta, a 14,179-foot active volcano, was still holding on to a handsome cap of snow and the landscape was vibrant and green. Asner’s spectrometer shared a different story. “Visual assessment doesn’t tell you much,” he said. On his computer screen, the green trees below were all reading red. They were dead. We just couldn’t see it yet. “A lot of this was not here last year,” he said with the clinical efficiency of a doctor diagnosing a cancer patient. CAO’s statewide findings suggest tens of millions of trees might not survive another dry winter.

    Sugar pine (Pinus lambertiana), a species that grows in large, contiguous groves and can live 500 years, has been hit the hardest, accounting for some 70 percent of the mortality, but cedar, fir, and oak are all suffering as well. It’s not just the lack of precipitation that’s killing these trees; it’s the cascading effect of climate change. Water-stressed trees make easier targets for mountain pine beetles (Dendroctonus ponderosae), which lay their eggs in the trunk and eat the trees.

    Using data collected by and visualizations generated by the Carnegie Airborne Observatory (CAO), scientists and forest managers can see both the current and future impacts of drought on Sequoia National Park. Learn what CAO scientist Greg Asner sees in this image.

    Asner shared a map of the Giant Forest. The sequoias were a cool, comforting shade of blue, demonstrating high water content. Water seeks its low point, Asner explained, and the Giant Forest sits in a plateau cup. “It’s an oasis, a refugio. Right now, those trees are of least concern.” It was bittersweet news, like celebrating the last house standing after a tornado.

    “Drought is a cumulative process,” Asner explained as the plane made a long bank off the western slope of Shasta. “Forests have biological inertia. We don’t know where the physiological tipping point is. Currently, we’re losing carbon from the forest.”

    Forests are supposed to absorb carbon, so I wasn’t sure if I’d heard Asner correctly over the communication system. I tapped my headphones to make sure they were still working. “I’m sorry, did you just say the forests are releasing carbon into the atmosphere?” Automobiles, coal-fired power plants, cattle production—those are all carbon sources. But the mighty forests of California?

    “That’s my guess,” he said. “It’s hard to imagine the forests are still carbon sinks.”

    Of the hundreds of feet it takes to climb to the top of a giant sequoia, the first six are invariably the most difficult.

    After two days on the ground watching the rest of the team sliding up and down the sequoias, I ask Ambrose for a tutorial. Over the years, I’ve spent enough time on rock and rope to scratch my way up a 5.10, but tree climbing—beyond the scampering variety, anyway—is new territory.

    It looks easy enough. Ambrose has been powering into the canopy in minutes, and Baxter has a fancy one-legged technique that looks like she’s hopping on air. I, meanwhile, can barely get 12 inches off the ground. Those charming fire caves that serve as a window to ancient battles? They’re actually hazardous overhangs that cause a climber to pendulum into a cavern of charred pith. The two feet of duff piled up on the root system? That makes it just hard enough to get the clearance from the tree trunk needed to begin a comfortable climb. I’ve never done the splits, but with my feet strapped into the stirrups I find myself spinning, spread-eagled in endless, dizzying circles. Then I sprain my knee.


    If Ambrose and Baxter climb their ropes like graceful inchworms, I look like a marionette having a seizure. Eventually I reach the lower canopy but my knee feels like a water balloon in a pressure cooker and I’m a long way from mastering Baxter’s hop-along trick. I descend in the interest of doing more climbing later in the week.

    Back on the ground, I limp over to Ambrose and tell him of my failed attempt. “It’s tricky the first time. You want to avoid gripping the ascenders too tightly. And really, you shouldn’t be using your upper body very much at all. You mostly want to use knees and core.” Translation: The exact opposite of what I was doing.

    A few days later I get my chance on another pre-dawn climb. The tree is one of the largest individuals in the world—220 feet tall and 20 feet in diameter at the base—all the more impressive considering it’s growing in shallow soil atop a plate of granite. Underground, the tree’s been waging war with its rocky substrate for millennia, its roots probing every crack and fracture in a tireless search for water. I clear the first few feet without issue and begin the long journey to the top.


    The sequoia is shaped like a giant barrel, tall and fat with hardly a taper. For the first ten stories, the trunk is a sheer wall of wood with an uninterrupted profile. I pass the crown of a neighboring 90-foot pine before even reaching the first branch of the sequoia. As I enter the sprawling branch network of lower canopy, the climb shifts from a smooth glide to a bruising slugfest. I work my way over, around, and between branches, each the size of a normal tree. About half way up, a pair of branches five feet thick shoots out from opposite sides of the trunk and up in an L-shape, like two arms flexing in a proclamation of strength.

    Finally, the top. After 40 minutes of climbing, I take a seat to catch my breath. The crown is gargantuan. On one side a half dozen branches converge to create a bench wide enough for a square dance. It’s easy to get lost in the scale, but as my heart slows and the morning brightens, the subtleties stand out. Thousands of green cones the size of ping-pong balls hang from the branches like chandeliers. Unlike the lower sections of the tree, the bark here is smooth and seamless with a purple tint, and etched with fine lines like topographic contours. A menorah of knobby vertical branches, called reiterated trunks, sprouts out of the crown. I scamper up the last 10 feet and perch on the stumpy tip of one of the spires.



    The crowns of sequoias punctuate the tree line like bushy, green exclamation points. Surrounded only by a warm breeze and empty space, I find myself completely exposed and suffering through an emotional paradox. There’s freedom up here with the birds, a glorious release from anything familiar. But it’s a narrow liberty. The laws of gravity and my seismic discomfort of heights dissuade me from any spread-eagle “I’m King of The World” moments. A western tanager (Piranga ludoviciana) lands on a branch and swivels its bright red head toward me, confused by the interloper in its realm. On the forest floor, a black bear (Ursus americanus) lumbers about for breakfast. More people have summited Everest—more people have probably walked on the moon—than have stood atop this noble tree.

    “There is absolutely no limit to its existence,” John Muir wrote of the sequoia in Our National Parks. “Nothing hurts the big tree.” The sunrise, however, reveals an unsettling future. Even here, in the country’s second-oldest national park, the horizon is the sickly yellow of a cigarette butt, a vaporous mixture of Central Valley smog and forest fire smoke from the myriad infernos burning across the state.

    Muir’s hyperbole is understandable. The tree I’m sitting atop probably took root before Athenian democracy sprouted in ancient Greece. It has lived through the rise and fall of many of the world’s great civilizations, from Romans to Mayans to the British Empire. Its long shadow has spread over this forest for three millennia, but that can’t obscure the exhaust of human progress. As I clip my climbing descender onto the rope and begin the journey to the forest floor, I can’t help but wonder: Will this tree stand long enough to witness our own demise? Or will it fall first?

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc
%d bloggers like this: