JON CARTWRIGHT – Page 27 – & THREE QUARKS EDITORIAL

Classically quantum

Physics WorldJon Cartwright7 November, 2013

Published in Physics World, 7 Oct 2013

They may look like simple oil drops, but they evoke many of the strange features of quantum theory. Coincidence? Jon Cartwright investigates

Waves can be particles, and particles can be waves. Scientists have struggled to come to terms with this strange feature of the quantum world ever since the French physicist Louis de Broglie first described wave–particle duality in 1926. Are entities waves and particles at the same time – “wavicles” maybe? Or do they switch somehow, depending on the situation? The nature of wave–particle duality seems impossible to understand, because no-one has ever observed something being both a particle and a wave in the everyday?world.

At least, that’s what physicists thought. In 2005 Yves Couder and Emmanuel Fort at Paris Diderot University discovered an odd phenomenon. If they placed an oil bath on a vertical vibrator, any oil droplets released onto the surface would not coalesce with the rest of the fluid, as you would expect. Instead the droplets would bounce up and down – their impact cushioned by a pocket of air – while generating circular standing waves.

Adjusting the amplitude of the vibrations, Couder and Fort noticed something even stranger happening. The droplets began to fall onto the wave crests in such a way that they were propelled across the surface. They bounced off the sides of the bath and one another, but always at a distance and never coming into direct contact. It was as though the waves were guiding the droplets to perform an elegant dance – to flit past and spin around one another, but never to collide.

These wave–droplets – or “walkers”, as the researchers began to call them – appeared to be the first macroscopic example of wave–particle duality. The waves could not exist without the droplets, nor could the droplets move without the waves. When a droplet eventually sunk, its corresponding wave would vanish; similarly, if a wave was damped, the droplet would stop moving around the oil bath.

Eight years on, Couder and Fort have discovered more and more ways in which their walkers can reproduce phenomena previously considered unique to quantum mechanics – from quantized orbits, to single-particle interference in a Young’s double-slit experiment. The similarities are so marked that many researchers have begun to question whether there could be more to it than mere coincidence. Could a simple, classical experiment reveal something about how the quantum world ticks, and even lead to a deeper theory?

“I find these results really, really fascinating,” says Aephraim Steinberg, an experimental quantum physicist at the University of Toronto in Canada. “And I think many people should find them striking.” […]

The rest of this article is available here.

CT bone scan helps assess osteoporosis

MPWJon Cartwright5 November, 2013

Published in MPW, 5 Nov 2013

Researchers in the UK and Greece have developed a technique that assesses the quality of bone in three dimensions. The technique, which uses CT to measure a bone’s ratio of calcium to phosphorous, could help in the diagnosis and treatment of osteoporosis.

Osteoporosis causes bones to become much weaker than normal, and more liable to fracture. According to worldwide figures from the World Health Organization, the condition causes some nine million fractures every year, more than 4.5 million of which are in the Americas and Europe. […]

The rest of this article is available here.

Ramping radioluminescence resolution

MPWJon Cartwright1 November, 2013

Published in MPW, 1 Nov 2013

Scientists in the US have significantly improved the resolution of a technique used to image radionuclide uptake in individual living cells. Known as radioluminescence microscopy, the technique is now able to image the uptake of molecules even when two cells are very close together.

Radioluminescence microscopy was invented in 2010 by medical engineer Guillem Pratx and colleagues at Stanford University in California, to see how small molecules interact with living cells. Single molecules could already be seen with a technique known as fluorescence microscopy – but only if they were fluorescent. Pratx and colleagues wanted a technique that also worked for non-fluorescent molecules. […]

The rest of this article is available here.

Iranian PhD student wins human-rights prize

Physics WorldJon Cartwright1 November, 2013

Published in Physics World, 1 Nov 2013

A physicist imprisoned in Iran while on a break from his PhD studies in the US has been awarded a human-rights prize. Omid Kokabee, who had been based at the University of Texas in Austin, has been given the Andrei Sakharov Prize from the American Physical Society (APS) for “his courage in refusing to use his physics knowledge to work on projects that he deemed harmful to humanity, in the face of extreme physical and psychological pressure”.

Kokabee, who was working towards a PhD in optics at Austin, was arrested at a Tehran airport while on vacation in Iran from the US in early 2011. He was charged with receiving “illegal earnings” and “communicating with a hostile government”, and detained at the notorious Evin Prison in north-west Tehran. In May 2012 he was sentenced to 10 years behind bars. […]

To read the rest of this article, please email for a pdf.

Improved carbon capture could cut emissions

HorizonJon Cartwright28 October, 2013

Published in Horizon, 28 Oct 2013

Techniques are being devised to capture greenhouse gases such as carbon dioxide and methane from the burning or extracting of fossil fuels – before they cause damage to the atmosphere.

Carbon capture techniques have long been considered a good intermediate step in the fight against climate change, because they make existing power plants and heavy industries more environmentally friendly while research continues into renewable sources of energy. […]

The rest of this article is available here.

Better, more versatile silicon-free solar cell technologies

HorizonJon Cartwright16 October, 2013

Published in Horizon, 16 October 2013

Researchers are working on ways to make silicon-free solar cells that are more energy-efficient.

The performance of solar cells depends largely on the material they are made of, and silicon, the base for most solar cells, is cheap to make, but as a thin film converts at most 10 % of sunlight to electricity.

However, copper indium gallium diselenide (CIGS) solar cells convert about 13 % of sunlight to electricity, and that has been extended to over 20 % in the lab.

Those are attractive figures for the European Union, which has promised to reduce greenhouse gas emissions by at least one-fifth below 1990 levels by 2020. Part of this cutback is expected to come from the more widespread adoption of efficient solar power. […]

The rest of this article is available here.

Warming is not the crucial uncertainty

Energy & EnvironmentJon Cartwright13 October, 2013

Published in ERW, 13 Oct 2013

A study by researchers in the US suggests that information on the impacts of climate change and the development of future technology is critical when it comes to making climate-related policy. The study contradicts the widely held belief that uncertainties in the amount of future global warming are the most important.

Governments often have to perform cost-benefit analyses to determine which is the best climate policy. For instance, a more stringent fuel-efficiency target may cost car companies money to implement today, but that must be weighed up against the potential environmental damage, in terms of cost, that higher emissions would generate in the future. Such costs cannot be known for certain; they always have a degree of uncertainty. […]

The rest of this article is available here.

Quasicrystals discovered in oxides

Chemistry WorldJon Cartwright10 October, 2013

Published in Chemistry World, 10 Oct 2013

Scientists in Germany have discovered quasiperiodic crystals, or quasicrystals, in oxide materials. The discovery suggests there could be many more quasicrystals out there, despite only a few having been found to date.

Quasicrystals are structures that have the general ordering but not the exact periodicity of ordinary crystals. Put simply, if you made a copy of a crystal’s structure in one place and then overlaid it in another, the two structures would align perfectly; the same is not true for quasicrystals. […]

The rest of this article is available here.

Graphene targets water treatment and carbon capture

Chemistry WorldJon Cartwright3 October, 2013

Published in Chemistry World, 3 Oct 2013

Two independent groups of researchers have demonstrated graphene-based membranes that can separate gas molecules according to their size and shape. One of the membranes separates hydrogen from nitrogen and carbon dioxide, while the other membrane separates carbon dioxide from nitrogen, and could be used in carbon capture processes to curb greenhouse emissions.

Graphene is an atom thick layer of graphite made up of carbon atoms arranged in hexagons, like atomic-scale chicken wire. Since the material was first produced in 2004 – an achievement recognised by the 2010 Nobel prize for physics – scientists have discovered it has a host of superlative optical, electronic and mechanical properties. Another property which scientists have been interested in, however, is its permeability to gases. If graphene were permeable to different gas molecules, it could be used as a filter and, as it’s one atom thick, it could separate molecules very quickly. […]

The rest of this article is available here.

How power plants can reduce drought

Energy & EnvironmentJon Cartwright3 October, 2013

Published in ERW, 3 Oct 2013

Drought-prone regions may be able to free up precious freshwater by shifting around their power generation. That’s the conclusion of a US group of researchers, who have shown in a Texan case study that the process could make available an amount of water equivalent to the daily use of 1.5% of the state’s population.

In many parts of the world, droughts are expected to become more extreme and more frequent as a result of climate change. The US experienced an almost record-breaking drought between 1998 and 2004, and saw shorter-term severe droughts in the midwest last year, and in Texas in 2011. […]

The rest of this article is available here.