This summer, Japan’s golden solar sail unfurled in space, becoming the first successful mission to sail on the physical pressure of the sun’s radiation. Its success led dreamers like Planetary Society director Bill Nye to envision a future of machines pushed forward by the pressure of lasers to explore the cosmos. And now, down here on Earth, researchers say they have demonstrated one of the key principles needed to realize such a vision: a “lightfoil” that uses light to create lift.
The lightfoil described in Nature Photonics is only micrometers in scale, but lead researcher Grover Swartzlander argues that it shows scientists can create and control optical lift. It operates on the property of refraction–how glass bends light.
Optical lift is different from the aerodynamic lift created by an airfoil. A plane flies because air flowing more slowly under its wing exerts more pressure than the faster-moving air flowing above. But in a lightfoil, the lift is created inside the object as the beam shines through. The shape of the transparent lightfoil causes light to be refracted differently depending on where it goes through, which causes a corresponding bending of the beam’s momentum that creates lift. [Science News]
This neat trick could potentially be used to steer a spacecraft, the researchers say.
Samuel T. Cohen had a different view of warfare than most, and it’s no surprise—he invented one of history’s most controversial weapons, the neutron bomb. He died on Sunday.
Cohen’s ingenious, deadly device actually packed far less destructive power than typical nuclear weapons (which he worked on with the Manhattan Project during World War II). The neutron bomb’s detonation sent out a barrage of neutrons, the neutral subatomic particles in atoms, that passed right though inorganic material but killed living things within its blast radius.
All nuclear explosions produce a rain of potentially lethal neutrons, uncharged particles from an atom’s nucleus, and Mr. Cohen, by adjusting components and reshaping the bomb shell, limited the blast and released more energy as neutrons. [The New York Times]
After the Manhattan Project, Cohen went to work for the RAND Corporation, where he developed his bomb.
He said the inspiration for the neutron bomb was a 1951 visit to Seoul, which had been largely destroyed in the Korean War. In his memoir, he wrote: “If we are going to go on fighting these damned fool wars in the future, shelling and bombing cities to smithereens and wrecking the lives of their inhabitants, might there be some kind of nuclear weapon that could avoid all this?” [Los Angeles Times]
Between murders and leaked documents, there’s disarray and intrigue all around Iran’s burgeoning nuclear program.
Yesterday, two prominent nuclear scientists in Iran were attacked in car bombings.
According to [Iranian new service] Fars, scientists Majid Shahriari and Fereydoun Abbasi were parking their cars in separate locations near the university campus about 7:45 a.m. local time when they were attacked.Witnesses said each car was approached by a group of men on motorcycles, who attached explosives to the vehicles and detonated them seconds later, the news agency reported. Shahriari was killed instantly. Abbasi was wounded. Both men were with their wives, who were also wounded. [Washington Post]
Unsurprisingly, Iranian President Mahmoud Ahmadinejad quickly pointed the finger of blame at the West and Israel. Both of the targeted scientists are reportedly connected to the Iranian nuclear program, which the government maintains is for the purpose of energy, but the United States and other nations oppose out of fear of an Iranian bomb.
Abbasi-Davani, whose handful of publications on neutron physics are mainly in Iranian journals, is a key figure in Iran’s nuclear programme. He is reported to be a scientist at the country’s defence ministry, and a member of Iran’s revolutionary guards since the 1979 Islamic Revolution. He was also named as being among “Persons involved in nuclear or ballistic missile activities” in the 2007 UN Security Council Resolution 1747, which imposed sanctions on Iran over its refusal to stop enrichment of uranium. [Nature]
Earlier this month CERN’s smashing machine switched from sending protons zinging around its ring to sending heavy lead ions at relativistic speeds. Those energetic collisions, the physicists now say, have allowed them to use the LHC’s ALICE experiment to glimpse quark-gluon plasma, the “primordial soup” present just after the Big Bang.
During this time, the Universe would have been so hot and energetic that the particles making up the elements we know today were unable to form, leaving the constituents to float “free” as a primordial soup. Quarks and gluons were only able to condense into larger particles when universal energy conditions were low enough. Hadrons (i.e. particles made from quarks; including baryons like neutrons and protons) were only allowed to form 10-6 seconds after the Big Bang. [Discovery News]
The Big Bang was not the beginning, Roger Penrose believes.
The eminent Oxford physicist has long advocated the wild idea of “conformal cyclic cosmology,” a cyclical universe without beginning or end in which the Big Bang 13.75 billion years ago was simply one of many. This month, Penrose pushed his idea further: His team says it has detected a pattern in the cosmic microwave background—radiation left over from just after the Big Bang—that represents the echo of events that occurred before the Big Bang itself.
Penrose examined the data from the Wilkinson Microwave Anisotropy Probe (WMAP), the mission that just completed nine years of surveying the cosmic microwave background across the sky. His study points to concentric circular patterns in the WMAP data where he says he found something surprising:
The circular features are regions where tiny temperature variations in the otherwise uniform microwave background are smaller than average. Those features, Penrose said, cannot be explained by the highly successful inflation theory, which posits that the infant cosmos underwent an enormous growth spurt, ballooning from something on the scale of an atom to the size of a grapefruit during the universe’s first tiny fraction of a second. Inflation would either erase such patterns or could not easily generate them. [Science News]
Researchers report this week in Nature that they’ve managed to corral atoms of antimatter in the lab and keep them around for about one-sixth of one second—an eternity in particle physics. The ability to trap these atoms means scientists could soon have the ability to study them directly, and perhaps answer one of the fundamental questions of the universe: Why the matter and antimatter present after the Big Bang didn’t annihilate each other completely and leave a matter-less universe behind.
It’s not easy, because of that mutual-annihilation issue. Hangst said the first trick was to combine the particles in a super-cold vacuum setting — less than 0.5 Kelvin, or -458.8 degrees Fahrenheit. That way, the particles don’t instantly jump away and fizzle out. The second trick is to build a magnetic trap to help contain the particles so that they don’t instantly decay. And there’s a third trick: designing a system capable of verifying that the atoms actually exist. “You must have a trap, and you must be cold, and you must be able to detect that you’ve done this,” Hangst said. [MSNBC]
First came the formulation of an invisibility cloak that could bend light around an object. Then, this spring, German scientists took that idea and made it three-dimensional. Is the invisibility cloak now ready to go 4D? For a study in the Journal of Optics, British researcher Martin McCall’s team adds the dimension of time to the invisibility cloak idea, creating a theoretical “space-time cloak.”
The key feature of the proposed space–time cloak is that its refractive index — the optical property that governs the speed of light within a material — is continually changed, pulling light rays apart in time. When the leading edge of a light wave hits the cloak, the material is manipulated to speed up the light, but when the trailing edge hits, the light is slowed down and delayed. “Between these two parts of the light, there will be a temporal void — a space in which there will be no illuminating light for a brief period of time,” explains McCall. [Nature]
Taking advantage of these differences, he says, it is theoretically possible to imagine a cloak that allows you—at least from my point of view—to transport instantaneously across space.
Cats have been our companions for almost 10,000 years. They have been worshipped by Egyptians, killed (or not) by physicists, and captioned by geeks. And in all that time, no one has quite appreciated how impressively they drink. Using high-speed videos, Pedro Reis and Roman Stocker from the Massachusetts Institute of Technology has shown that lapping cats are masters of physics. Every flick of their tongues finely balances a pair of forces, at high speed, to draw a column of water into their thirsty jaws.
Read the rest of the post at Not Exactly Rocket Science, where Yong explains that each sip is a tug-of-war between inertia and gravity. Here’s a little of that high-speed video:
If a country fires an airborne nuclear missile, the source of the attack is obvious. But what about the more fluid threat that hangs over the 21st century—terrorists sneaking a nuclear device into a city and setting it off? In a study in the Proceedings of the National Academy of Sciences this week, researchers suggest that even in the charred aftermath of a nuclear explosion, there could be evidence left behind that helps to identify the source of the bomb.
Physicist Albert Fahey and company went back to the beginning of the atomic age, to the United States’ first atomic bomb test in New Mexico in July 1945. As that bomb test was called “Trinity,” the glass left behind by the blast is called “trinitite.” Fahey obtained some of that glass to show that all these years later, it still contained evidence of the bomb’s makeup.
“Prior to this study, people didn’t realise that other components of the bomb could be discerned from looking at ground debris and seeing what’s associated [with it],” said Dr Fahey. “But there are some distinctive signatures that were in the bomb other than fission products and plutonium, and that gives you hope that you can get some additional information out of it – like where it was made.” [BBC News]
New neuroscience research is not only adding to our understanding of math and number processing in the brain, it’s also suggesting a way to improve learning in the math-deficient.
A small new study published in Current Biology involved electrical stimulation of the parietal lobe, a part of the brain involved in math learning and understanding. When this area was stimulated, students performed better on a math problem test. Said study leader Cohen Kadosh:
“We’ve shown before that we can induce discalculia [an inability to do math], and now it seems we might be able to make someone better at maths, so we really want to see if we can help people with dyscalculia…. Electrical stimulation is unlikely to turn you into the next Einstein, but if we’re lucky it might be able to help some people to cope better with maths.” [BBC News]
Dyscalculia is a learning disability similar to dyslexia, in which a person has an innate difficulty with learning or understanding math. People with this condition can have trouble with daily arithmetic, telling left from right, and telling time on analog clocks. Some studies estimate up to five percent of the population suffers from dyscalculia, and about 20 percent have less severe troubles with math.
For the experiment, 15 students were hooked up to a transcranial direct current stimulation (tDCS) machine, which stimulates the brain through the skull with 1 milliamp of electricity, and were given either a positive (right to left) zap to their parietal lobe for 20 minutes, a positive zap for 30 seconds, or a negative (left to right) zap for 20 minutes (five students per group). The current produced a tingling sensation in the scalp, but it didn’t hurt. Then the students were trained to learn the assigned number values of made-up symbols.
When neutrinos change from one phase to another, they tell us something about their mysterious nature. These ghostly subatomic particles come in three flavors, physicists say: muon, tau, and electron. Just this summer, a team caught a neutrino in the act of changing from muon to tau, a finding that backed up the argument that these particles do, in fact, have mass. This week, a new study of neutrino oscillation—the changing of flavors—suggests an deeper mystery, and implies that these three flavors of neutrino may not be enough to account for these particles’ behavior.
In Physical Review Letters, a large group of physicists published their study from the MiniBooNE experiment at Fermilab in Illinois. When the physicists looked at oscillations of muon antineutrinos into electron antineutrinos, they found the process happening faster than known physics predicts. Neutrinos followed the rules, but antineutrinos didn’t behave the same way did.
So what does it mean? We asked physicist Silvia Pascoli at the U.K.’s Durham University to explain:
Is 3D technology the next big wave in video? Or should we skip right ahead to holography? New research is developing ways to stream almost-live video to holographic display, providing a three-dimensional, realistic image without the need for those dorky plastic 3D glasses. And before you ask–yes, this does bring us one step closer to living in a Star Wars world, where holographic princesses deliver desperate pleas for help.
This is the first time researchers [have demonstrated] an optical material that can display “holographic video,” as oppose to static holograms found in credit cards and product packages. The prototype looks like a chunk of acrylic, but it’s actually an exotic material, called a photorefractive polymer, with remarkable holographic properties. [IEEE Spectrum]
The prototype, produced by Nasser Peyghambarian and colleagues at the University of Arizona and Nitto Denko Technical Corporation, displays a holographic image that can be updated every two seconds. This is much better than the four minutes between updates seen in the team’s last prototype, and it gives the audience an almost-real-time representation of what’s happening on the other end of the communication (be it in the other room or across the country). The team expects to continue improving their technology, enabling larger pictures and shorter refresh times.
Hit the break for more details and an additional video…
About two-fifths of marathon runners “hit the wall” on the big day. That means they completely deplete their body’s stash of readily available energy, which makes them feel wiped out and severely limits their running pace; it sometimes forces people out of the run completely.
Marathoner and biomedical engineer Benjamin Rapoport has been physically and mentally struggling with this phenomenon for years, and had the bright idea to turn it into a research project. He published a mathematical theory in the journal PLoS Computational Biology describing how and why runners hit the wall–and how they can avoid it.
By taking into account the energy it takes to run a marathon, the body’s energy storage capacity and the runner’s power, the researchers were able to accurately calculate how many energy-rich carbohydrates a runner needed to eat before race day and how fast to run to complete all 26.2 miles (42 kilometers). [LiveScience]
Rapoport’s studies of marathoners were prompted by his desire to run in the Boston Marathon in 2005, and his teacher’s desire for him to be in class. In return for missing class, Rapoport was tasked with giving a class lecture on the physiology of the marathoner. That same year, Rapoport himself hit the wall while running the New York Marathon.
A new approach to electrophoresis is giving researchers more control over how they play with small particles.
Electrophoresis is the movement of particles in solution under a current–a phenomenon that can be exploited for use in everything from ePaper to DNA separating gels. Instead of using a normal fluid to conduct current, researchers led by Oleg Lavrentovich tried using liquid crystals as their conductive fluid.
Liquid crystals, like those seen in the first three pictures above (which might look similar to the patterns you’ve seen when you push on the screen of some of your electronics), act like a fluid. But instead of being a disorganized jumble of molecules, the individual rod-shaped particles line up parallel to each other. When they take on different orientations, they refract different colors of light, a phenomenon called birefringence.
The world is not smooth, made of perfect spheres and unbroken lines. Its edges are tattered and torn, ragged yet recognizable. Last week the world lost the man whose mathematics helped to explain those patterns we see all the time in nature.
On Thursday, Benoît Mandelbrot died. His great book The Fractal Geometry of Nature appeared in 1982, and its fascinating notion rests on the idea of a shape becoming more and more complicated the further in one zooms.
“Fractals are easy to explain, it’s like a romanesco cauliflower, which is to say that each small part of it is exactly the same as the entire cauliflower itself,” Catherine Hill, a Gustave Roussy Institute statistician, [says]. “It’s a curve that reproduces itself to infinity. Every time you zoom in further, you find the same curve.” [PC World]
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
This summer, Japan’s golden solar sail unfurled in space, becoming the first successful mission to sail on the physical pressure of the sun’s radiation. Its success led dreamers like Planetary Society director Bill Nye to envision a future of machines pushed forward by the pressure of lasers to explore the cosmos. And now, down here on Earth, researchers say they have demonstrated one of the key principles needed to realize such a vision: a “lightfoil” that uses light to create lift.
Samuel T. Cohen had a different view of warfare than most, and it’s no surprise—he invented one of history’s most controversial weapons, the neutron bomb. He died on Sunday.
Between murders and leaked documents, there’s disarray and intrigue all around Iran’s burgeoning nuclear program.
Now that the 
The Big Bang was not the beginning, 
It’s a trap! (For antimatter.)
First came the formulation of an 
If a country fires an airborne nuclear missile, the source of the attack is obvious. But what about the more fluid threat that hangs over the 21st century—terrorists sneaking a nuclear device into a city and setting it off? In a 
When neutrinos change from one phase to another, they tell us something about their mysterious nature. These ghostly subatomic particles come in three flavors, physicists say: muon, tau, and electron. Just this summer, a team 
About two-fifths of marathon runners “hit the wall” on the big day. That means they completely deplete their body’s stash of readily available energy, which makes them feel wiped out and severely limits their running pace; it sometimes forces people out of the run completely.
The world is not smooth, made of perfect spheres and unbroken lines. Its edges are tattered and torn, ragged yet recognizable. Last week the world lost the man whose mathematics helped to explain those patterns we see all the time in nature.
