Science

First sight?: CERN’s ATLAS collaboration claims to see light-by-light scattering for first time The idea that particles of light can interact with one another – known as light-by-light scattering – has finally been observed some 80 years after it was first predicated. That’s the claim of members of the ATLAS collaboration at CERN in Geneva, who have combed through data they took in 2015 when lead ions collided with each other in their detector. Some scientists, however, dispute the priority of the finding, arguing that light-by-light scattering was observed by an experiment at the SLAC National Accelerator Laboratory in California 20 years ago. Classically, light cannot interact with light because photons – even though they mediate interactions between charged particles – do not themselves carry charge. However, Heisenberg’s uncertainty principle, a cornerstone of quantum mechanics, says that photons can briefly transform into “virtual” pairs of particles and antiparticles, such as electrons and positrons. There is …

My precious: Did imploding neutron stars produce the gold in your jewellery? Precious elements may come from spinning neutron stars that have swallowed a tiny black hole and imploded. If true, this dramatically changes our understanding not only of how rare elements like gold are made, but also the nature of some dark matter. The elements in question include all atoms heavier than bismuth, as well as some neutron-rich isotopes heavier than iron. They are forged in what is called the r-process (meaning ‘rapid’), which requires copious numbers of neutrons as well as densities ten billion times greater than those found in the Sun’s core to enable the rapid capture of those neutrons by atomic nuclei. Therefore, the r‑process can only take place in the most extreme environments. In 1957, Burbidge–Burbidge–Fowler–Hoyle (known as B2FH) proposed that core-collapse supernovae were the origin of the r‑process elements, but in recent years this has fallen into doubt. Binary neutron …

Compact detection: small and portable neutrino detector creates excitement Detecting neutrinos is one of the hardest tasks in particle physics, owing to their extremely low interaction rate with particles. Huge quantities of matter are monitored just to catch a precious few events. Now, however, researchers have unveiled a new technique to catch neutrinos with much smaller detectors. It could potentially lead to extensions of the Standard Model of particle physics, and also have practical applications in nuclear non-proliferation. Neutrinos were first detected in 1956 through inverse beta decay – an observation that would eventually win the 1995 Nobel Prize in Physics. They are detected by the weak interaction, which is mediated by the exchange of charged W and neutral Z bosons. A neutrino scattering off a proton exchanges a W boson, producing a neutron and a positron. Although this can provide valuable information, it can only detect neutrinos with fairly high energy. Alternatively, one can …

Pit of doom: the mass of an ant dictates its fate in sand pits For an ant that’s fallen into a pit dug in the sand by the larvae of “antlion” insects, the ability to climb up a granular slope is a matter of life or death. Now, a group of scientists in France has discovered why certain medium-sized ants are unlikely to make it out alive of these conical, centimetre-sized traps – no matter how hard they try. The physics of friction, the researchers found, dictates that these ants are heavy enough to deform a pit’s sandy slope but not so heavy that they create stabilising footprints. Instead, the unlucky creatures slide to the bottom of the pit and are eaten alive. It was a 17th-century French scientist – physicist Guillaume Amontons – who formulated three laws of friction still in use today. The first states that the frictional force experienced by an object …

Lift off: The Cosmic Ray Energetics And Mass for the International Space Station launches from NASA’s Kennedy Space Center in Florida NASA has launched a space-based probe that will study the origins of highly energetic particles, known as cosmic rays. Sent into space by a Space X rocket yesterday, the Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) will now be installed on the Japanese Experiment Module, where it will study cosmic rays for three years. Cosmic rays zoom through space at nearly the speed of light and consist of a range of particles from protons to carbon atoms. When cosmic rays enter the Earth’s atmosphere they collide with another particle setting off a cascade of secondary particles. While Earth-bound detectors only see the secondary particles, a probe that is above Earth’s atmosphere will be able to spot the primary particles. ISS-CREAM is a successor to six similar missions that have flown …

Smart shades: solar cells instead of traditional lenses can generate power The dark lenses of sunglasses have been replaced with organic solar cells by scientists in Germany. The cells are able to power a small mircocontroller that sends information on ambient conditions to a couple of displays in the spectacle arms, and in future might provide power for personal devices such as hearing aids. Organic solar cells are less efficient than conventional silicon devices and not as resistant to continuous strong sunlight, making them less suited to providing power from rooftops. But, according to team member Daniel Bahro of the Karlsruhe Institute of Technology (KIT), the fact that they are light, flexible and transparent opens up a number of new, previously impractical applications. Bahro and colleagues designed the new “lenses” to have a similar weight and transmission spectrum to those in normal sunglasses. The lenses are made from a polymer and two types of fullerene …

Smart shades: solar cells instead of traditional lenses can generate power The dark lenses of sunglasses have been replaced with organic solar cells by scientists in Germany. The cells are able to power a small mircocontroller that sends information on ambient conditions to a couple of displays in the spectacle arms, and in future might provide power for personal devices such as hearing aids. Organic solar cells are less efficient than conventional silicon devices and not as resistant to continuous strong sunlight, making them less suited to providing power from rooftops. But, according to team member Daniel Bahro of the Karlsruhe Institute of Technology (KIT), the fact that they are light, flexible and transparent opens up a number of new, previously impractical applications. Bahro and colleagues designed the new “lenses” to have a similar weight and transmission spectrum to those in normal sunglasses. The lenses are made from a polymer and two types of fullerene …

Living insects can now be scanned in unprecedented 3D detail without being harmed. The scanning method developed by scientists at Western University in Canada relies on an insect’s ability to survive low-oxygen environments and high-ionizing radiation doses. Standard methods for looking inside insects involve using dead specimens or killing the bug during the imaging process. “We essentially had snapshots, moments in time, when what we needed were dynamic images of insects’ internal development,” says biologist Joanna Konopka. “We thought, what would happen if we tried to image them live?” Bug’s life Konopka therefore teamed up with biophysicist Danny Poinapen to develop a non-invasive technique. Using a steady flow of carbon dioxide, they temporarily immobilized living insects – including Colorado potato beetles and true army worms – for up to seven hours. As the bugs were no longer wiggling around, the team could use X-ray micro-computed tomography (micro-CT) to clearly see the insects’ internal workings in …

Sunny science: the Sun still holds some mysteries for researchers The Sun’s core rotates four times faster than its outer layers – and the elemental composition of its corona is linked to the 11 year cycle of solar magnetic activity. These two findings have been made by astronomers using a pair of orbiting solar telescopes – NASA’s Solar Dynamics Observatory (SDO) and the joint NASA–ESA Solar and Heliospheric Observatory (SOHO). The researchers believe their conclusions could revolutionize our understanding of the Sun’s structure. Onboard SOHO is an instrument named GOLF (Global Oscillations at Low Frequencies) – designed to search for millimetre-sized gravity, or g-mode, oscillations on the Sun’s surface (the photosphere). Evidence for these g-modes has, however, proven elusive – convection of energy within the Sun disrupts the oscillations, and the Sun’s convective layer exists in its outer third. If solar g-modes exist then they do so deep within the Sun’s radiative core. A team led …

Health check: GLIM lets scientists look inside embryos The internal structures of live cow embryos have been imaged in 3D by researchers at the University of Illinois at Urbana-Champaign in the US. The method developed by Gabriel Popescu and colleagues could allow scientists to determine the health of embryos before in vitro fertilization in humans. Biomedical microscopy methods typically involve shining light through thin slices of tissue, or using chemical or physical markers that identify a specific object in a thick sample but can be toxic to living tissues. “When looking at thick samples with other methods, your image becomes washed out due to the light bouncing off of all surfaces in the sample,” says team member Mikhail Kandel. Imaging the depths Popescu and colleagues therefore developed a technique called gradient light interference microscopy (GLIM). The method uses two interfering light fields that are identical except for a small transverse spatial shift. By controlling the …

1 2 3 41