Geckos and spiders seem to be able to sit still forever upside down. But sooner or later the grip is lost, no matter how little force is acting on it. Engineers, using scanning electron microscopy, have recently demonstrated why this is so by showing how heat, and the subsequent movement of molecules at the nanoscale, eventually force loss of adhesion.
When a superconductor is exposed to a magnetic field, a surface current creates a magnetic field that cancels the field inside the superconductor. This phenomenon, known as the Meissner-Ochsenfeld effect, was first observed in 1933. In a research first, scientists have succeeded in measuring an analogue of the Meissner effect in an optical crystal with ultracold atoms. This validates theoretical predictions dating back more than 20 years.
Planet Mercury’s unusual metal-rich composition has been a longstanding puzzle in planetary science. According to a study published online in Nature Geoscience, Mercury and other unusually metal-rich objects in the solar system may be relics left behind by collisions in the early solar system that built the other planets.
A decade of research by Rice Univ. scientists has produced a 2-D model to prove how gas hydrate, the “ice that burns,” is formed under the ocean floor. Gas hydrate has potential as a source of abundant energy, if it can be extracted and turned into usable form. It also has potential to do great harm.
Overturning conventional wisdom stretching all the way to Leonardo da Vinci, new research from Israel shows that how things break and how things slide are closely interrelated. The breakthrough study marks an important advance in understanding friction and fracture, with implications for describing the mechanics that drive earthquakes.
Processes that shaped the ridges and troughs on the surface of Jupiter's icy moon Ganymede are likely similar to tectonic processes seen on Earth, according to a team of researchers led by Southwest Research Institute. To arrive at this conclusion, the team subjected physical models made of clay to stretching forces that simulate tectonic action.
An observatory run by the Univ. of Utah has found a “hotspot” beneath the Big Dipper emitting a disproportionate number of the highest-energy cosmic rays. The discovery moves physics another step toward identifying the mysterious sources of the most energetic particles in the universe.
An international research collaboration has designed a miniscule cooling element that uses spin waves to transport heat in electrical insulators. Although physicists have used spin for cooling purposes before, this is the first time that they have successfully done this in insulating materials. The cooling element could be used to dissipate heat in the increasingly smaller electrical components of computer chips.
Techniques for controlling ultra-cold atoms travelling in ring traps currently represent an important research area in physics. A new study out of Spain gives a proof of principle, confirmed by numerical simulations, of the applicability to ultra-cold atoms of a very efficient and robust transport technique called spatial adiabatic passage.
For the last century, the concept of crystals has been a mainstay of solid-state physics. Crystals are paragons of order; crystalline materials are defined by the repeating patterns their constituent atoms and molecules make. Now physicists have evidence that a new concept should undergird our understanding of most materials: the anticrystal, a theoretical solid that is completely disordered.
Robert Wolkow and his team at the Univ. of Alberta are working to engineer atomically precise computing technologies that have practical, real-world applications. In recent research, he and his team observed for the first time how an electrical current flows across the skin of a silicon crystal and also measured electrical resistance as the current moved over a single atomic step.
Determining the age of stars has long been a challenge for astronomers. Recent experiments by researchers in Belgium show that “baby” stars can be distinguished from “adolescent” stars by measuring the acoustic waves they emit. This is because stars can vibrate due to sound waves bouncing inside, and those waves are detectable through subtle changes in stellar brightness.
Fully automated "deep learning" by computers greatly improves the odds of discovering particles such as the Higgs boson, according to a recent study. In fact, this approach beats even veteran physicists' abilities, which now consists of developing mathematical formulas by hand to apply to data. New machine learning methods are rendering that approach unnecessary.
Known as the “world's longest experiment”, an experiment at the University of Queensland in Australia was famous for taking ten years for a drop of pitch, a black, sticky material, to fall from a funnel. A new test in the U.K. is using a different bitumen, or pitch, which is 30 times less viscous than the Queensland experiment, so that the flow can be seen at a faster rate and hopefully provide more insights.
The light-warping structures known as metamaterials have a new trick in their ever-expanding repertoire. Researchers at NIST have built a silver, glass and chromium nanostructure that can all but stop visible light cold in one direction while giving it a pass in the other. The device could someday play a role in optical information processing and in novel biosensing devices.
Experts don't fully understand how “plastic” solar panels work, which complicates the improvement of their cost efficiency and hinders wider use of the technology. However, an international team has now determined how light beams excite the chemicals in solar panels, enabling them to produce charge. Their findings were made possible with the use of femtosecond Raman spectroscopy.
Using a scanning tunneling microscope to visualize the electronic structure of the oxygen sites within a superconductor, a Binghamton Univ. physicist and his colleagues say they have unlocked one key mystery surrounding high-temperature superconductivity. The team found a density wave with a d-orbital structure, which is a pattern new to this type of superconductor and they may be found in all cuprates.
Researchers at Lawrence Berkeley National Lab and the Univ. of Hawaii have uncovered the first step in the process that transforms gas-phase molecules into solid particles like soot and other carbon-based compounds. The finding could help combustion chemists make more-efficient, less-polluting fuels and help materials scientists fine-tune their carbon nanotubes and graphene sheets for faster, smaller electronics.
Physicists in Europe have solved a mystery that has puzzled scientists for half a century. it has long been known that the distance between the graphene oxide layers depends on the humidity, not the actual amount of water added. But now, with the help of powerful microscopes, it can be seen how distance between graphite oxide layers gradually increases when water molecules are added, and why this phenomenon occurs.
Using the quantitative approach of physicists, biologists in Israel have developed experimental tools to measure precisely the bacterial response to antibiotics. Their mathematical model of the process has led them to hypothesize that a daily three-hour dose would enable the bacteria to predict delivery of the drug, and go dormant for that period in order to survive.
Aerospace engineers from the Univ. of Illinois, Urbana-Champaign are using the National Science Foundation-supported Stampede supercomputer to explore how jets in general, like those on modern aircraft and inside the human body, generate noise. This is important because no simple explanation of how jets generate noise is currently available, and without this understanding making jets quieter is difficult.
For his doctoral dissertation, Yu Chen developed a novel way to fabricate superconducting nanocircuitry. However, the extremely small zinc nanowires he designed did some unexpected things, including demonstrating dissipation characteristics though only to be present in normal states. After long and careful work, which involved both experimental and theoretical efforts, researchers have found an explanation that fits.
In quantum physics, momentum and position are an example of conjugate variables, connected by Heisenberg’s Uncertainty Principle, which says that both quantities cannot be simultaneously measured precisely. Univ. of Rochester physicists have recently shown that a technique called compressive sensing that offers a way to measure both variables at the same time without violating the Uncertainty Principle.
At the nanoscale, where objects are measured in billionths of meters and events transpire in trillionths of seconds, things do not always behave as our experiences with the macro world might lead us to expect. Water, for example, seems to flow much faster within carbon nanotubes than classical physics says should be possible. Now imagine trying to capture movies of these almost imperceptibly small nanoscale movements.
What is believed to be the smallest force ever measured has been detected by researchers with the Lawrence Berkeley National Laboratory and the Univ. of California, Berkeley. Using a combination of lasers and a unique optical trapping system that provides a cloud of ultracold atoms, the researchers measured a force of approximately 42 yoctonewtons.