Physics Today Daily Edition

Subscribe to Physics Today Daily Edition feed
Please follow the links to view the content.
Updated: 5 days 1 hour ago

From Florida to Fukushima

16 October 2014
Physicist Brian Beckford sets the bar high for himself, and he's helping students from underrepresented minorities do the same.

Hawking radiation from fluids

16 October 2014
In a Bose–Einstein condensate, a region of supersonic flow is analogous to the invisible interior of a black hole.

Australian student plans to build world's fastest glider

15 October 2014

Sydney Morning Herald: Three years ago Jason Brand used a weather balloon to loft a toy chicken 33 km above New South Wales, Australia. Now, at the age of 12, he is designing a remote-controlled glider that he believes could break the sound barrier. As with the chicken, he plans to use a balloon to lift the 9-kg, 2.5-m craft before releasing it. Unlike the chicken, he'll be in control of the glider and its descent via remote; he'll be able to see the glider with a pair of virtual-reality goggles linked to a camera in the glider's nose. With his father's help, he is running a Kickstarter campaign to raise the $80 000 they estimate it will cost to obtain the necessary equipment. In Jason's free time, he is also a student representative on a team competing for a Google Lunar XPrize to land a robot on the Moon.

Italy to require advanced biofuels in all vehicles

15 October 2014

BBC: A ministerial report has revealed that Italy will soon require a portion of all gasoline and diesel to contain advanced biofuels, which are made from waste material. Using advanced biofuels instead of traditional biofuels will reduce the amount of farmland being devoted to growing nonfood crops. Italy will require 0.6% of all fuel to be advanced biofuels by 2018, with an increase to 1% by 2022. That will make Italy the first European nation to have such a requirement. The European Union had attempted to set a similar goal for all member countries, but the final version was nonbinding. Last year the world's first plant that makes biofuel from straw opened near Turin, Italy, and there are plans to open three more similar plants in the southern part of the country.

Shape-shifting carbon-fiber materials could be used in aircraft

15 October 2014

MIT Technology Review: Materials that alter their shape in response to changes in electrical charge, temperature, or air pressure have been in use for decades. But they have not been widely employed in airplanes because of the extreme stresses they would be exposed to. Now Skylar Tibbets of MIT and his colleagues have partnered with Airbus to develop shape-shifting carbon-fiber composites that can be used in aircraft. The researchers are using unusual carbon-fiber materials—they are not rigid like normal carbon-fiber ones—from a startup named Carbitex. They use a 3D printer to add layers of shape-changing polymers to the carbon-fiber sheets. The resulting carbon-fiber composites can change shape in response to specific stimuli. The first application for the materials will likely be on air intake valves, which change size as a plane changes altitude, but they could potentially replace hydraulic actuators and hinges.

Give us your old physics books!

15 October 2014
By donating books to the Niels Bohr Library & Archives you can help historians trace the development of physics.

<em>MAVEN</em> images reveal solar wind stripping away Martian atmosphere

15 October 2014

Nature: NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft entered Martian orbit in September and began taking pictures of the planet using a UV spectrograph. Bruce Jakosky of the University of Colorado Boulder and his team have released the first of those images, which reveal that the solar wind is stripping hydrogen, oxygen, and carbon atoms from Mars's atmosphere. The carbon and oxygen atoms stay relatively close to the planet, but the hydrogen atoms, being much lighter, are sprayed into space. The images provide some direct evidence about the process that has slowly eroded the Martian atmosphere over billions of years. 

Study of CO<sub>2</sub> absorption by leaves suggests models overestimate atmospheric levels

14 October 2014

BBC: One of the variables that climate models include is a measure of how much atmospheric carbon dioxide is absorbed by plants. According to a new study of the absorption process by Lianhong Gu of Oak Ridge National Laboratory and his colleagues, the amount plants absorbed between 1901 and 2010 was actually 16% higher than most models had estimated. To reach that conclusion, Gu's team studied mesophyll diffusion—the way that CO2 spreads within leaves. Their analysis of several climate models has also led them to believe that the amount of atmospheric CO2 has been overestimated by 17%. They say their finding regarding plants' CO2 absorption would account for that discrepancy. Although the researchers' work may lead to an adjustment of climate models, it is unlikely to alter the general implications of increasing levels of atmospheric CO2 on climate change.

Recent global sea-level rise is unprecedented, says study

14 October 2014

Guardian: Over the past century, global sea levels have risen drastically. According to a recent study published in the Proceedings of the National Academy of Sciences, that rise stands in stark contrast with most of the current interglacial period, which extends back some 6000 years. Over most of that time, sea levels have not changed by more than 20 cm. Since the start of the 20th century, however, they have already risen by that much and show no sign of stopping. The researchers attribute the rise in sea levels to global warming brought on by ever-increasing anthropogenic carbon emissions. They based their study on remnants of tree roots and sea mollusks found in sea-floor sediments, which indicate which areas were covered by water and when. That evidence has shed light on some 35 000 years of the geologic record. Because of Earth’s slow dynamic response, the researchers predict that sea levels will continue to rise for the next several centuries, even if Earth’s governments manage to keep carbon emissions at present-day levels.

Galaxy leaking high energy radiation may provide clues to reionization epoch

14 October 2014

Los Angeles Times: The reionization epoch is the stage in the formation of the universe when the hydrogen atoms filling space were ionized and the universe became transparent to low-energy light. To achieve that ionization, highly energetic radiation was necessary, but where it came from is uncertain. One possibility is that early galaxies released large amounts of radiation in the extreme UV or higher—a range known as Lyman continuum radiation. However, galaxies trap most of the radiation in that range, with only a very few leaking as much 2% of the extremely high-energy radiation they produce. To initiate the reionization process, it is estimated that the early galaxies would have needed to release at least 20% of their extreme radiation. Now, researchers using the Hubble Space Telescope have found a galaxy that is leaking 21% of the radiation it produces in the Lyman continuum radiation. The galaxy, J0921+4509, is producing new stars at a massive rate of 50 solar masses per year, an order of magnitude greater than that of the Milky Way. It is possible that this rate of star creation is related to the amount of radiation escaping.

App could turn smartphones into vast cosmic-ray detector

14 October 2014

Ars Technica: Cosmic rays are constantly bombarding Earth. Trying to detect them to study their origins has proven to be a challenge because as they strike Earth’s atmosphere, they break up into showers of secondary particles. Even the largest detectors can only capture a few traces of the high-energy photons and other particles that manage to reach Earth’s surface. Now researchers at the University of California's Davis and Irvine campuses have proposed a novel design for a vast detector array that takes advantage of the global proliferation of smartphones. Their CRAYFIS (cosmic rays found in smartphones) app would make use of the digital sensors in the phones’ high-resolution cameras to watch for the high-energy particles—but only when the phone is inactive and plugged in for charging. Anyone interested can sign on for the beta testing of either the Android or iOS version.

Werner Weber

13 October 2014

New government initiative aims to boost photonics manufacturing in US

13 October 2014
The latest and largest of six manufacturing innovation institutions will close the gap between applied research and product development.

IPF 2014: The entrepreneurial professor

13 October 2014
A low-cost telescope and a handheld contaminant sensor are among the new products that academic researchers have brought to market.

Reversed diffraction in bio-inspired photonic materials

13 October 2014
Hierarchical structures in a butterfly's wing and in a lab produce novel optical effects.

<em>Wall Street Journal</em> op-ed disputes physics Nobel achievement’s provenance

13 October 2014
The prize committee is said to have “overlooked fundamental discoveries made at RCA four decades ago.”

Black hole analogue produces sonic Hawking radiation

13 October 2014

New Scientist: In 2009, Jeff Steinhauer of the Technion–Israel Institute of Technology in Haifa and his colleagues made a model of a black hole using a Bose–Einstein condensate (BEC) and a pair of lasers. The first laser held the BEC in a narrow tube, and the second accelerated a portion of the material so that it flowed faster than the speed of sound. That created two horizons, one where the material transitioned from still to supersonic and another inside that one where the material slowed again. Now Steinhauer’s group says that they have seen an analogue to Hawking radiation—the release of particles due to quantum effects near a black hole’s event horizon. For their sonic black hole, the radiation is in the form of phonons, “particles” of sound, which are created in pairs, with one phonon escaping and the other being trapped between the two horizons. It is the trapped phonons that the researchers saw, because as the particles bounce between the horizons, they create more phonon pairs, which amplifies the signal to the point that it could be detected.

Prehistoric icebergs may have drifted as far south as Florida

13 October 2014

Nature: Massive icebergs carried by prehistoric floods may have traveled down the North American coast as far south as Florida, according to a recent study published in Nature Geoscience. Some 20 000 years ago, as the North American ice sheet began to melt, giant icebergs up to 300 m thick appear to have broken off and been carried by the massive flooding not only into the northern Atlantic Ocean but also south along the continental shelf. The researchers’ findings are based on computer models and on the presence of massive seafloor scars believed to have been left as the icebergs scraped the ocean bottom. The meltwater discharge may also have caused a temporary reversal in surface ocean currents. Now that the Greenland ice sheet is in a period of rapid melt, with large icebergs calving off, researchers are working to understand how that influx of cold fresh water will affect present-day ocean circulation patterns and, possibly, global climate.

New smart device looks like tiny telescope

13 October 2014

MIT Technology Review: Besides smart phones, smart glasses, and smart watches, another smart device may soon hit the market: the Loupe. Resembling a tiny telescope, the Loupe is a cylinder the size of a lipstick tube that the user can hold up to one eye to view a kaleidoscope-like display of icons for Twitter, Facebook, Gmail, and so on. Touch electrodes on the exterior allow the user to manipulate the images on the screen, and a manual focusing ring sits near one end. The Loupe, named for the magnification device used by jewelers, is the latest in a wave of wearable technology that provides constant access to messages, news, and updates. A prototype of the device was presented this month by Nokia at the ACM User Interface Software and Technology Symposium in Honolulu, Hawaii.

Pages