JON CARTWRIGHT – Page 61 – & THREE QUARKS EDITORIAL

Supersolids seen in new light

Physics WorldJon Cartwright30 April, 2009

Published in Physics World, 30 Apr 2009

It’s a solid that’s not a solid — it can flow effortlessly through normal matter as if it were not there. This is a supersolid in principle, but for at least five years the true origin of this state of matter, if it is indeed real, has challenged the both minds and experimental prowess of physicists.

Now two studies by researchers in the US are giving new perspectives on the mystery, although it is far from being solved. […]

The rest of this article is available here.

Invisibility cloaks go optical

Physics WorldJon Cartwright28 April, 2009

Published in Physics World, 28 Apr 2009

Two independent groups of physicists claim to have demonstrated invisibility cloaks that operate for light at optical wavelengths.

Until now researchers had only been able to create invisibility cloaks for the microwave part of the spectrum. But last week Michal Lipson and colleagues at Cornell University uploaded a preprint on arXiv in which they describe the first demonstration of a cloak that can disguise objects from light in the near infrared to the far red. The following day Xiang Zhang and colleagues at the University of California at Berkeley uploaded a preprint in which they describe a cloak for just the near infrared.

Although Lipson’s group has submitted its preprint to Nature Photonics and is awaiting peer review, the work of Zhang’s group will soon be published in Nature Materials. […]

The rest of this article is available here.

Metal ions give rise to threaded molecules

Chemistry WorldJon Cartwright28 April, 2009

Published in Chemistry World, 28 Apr 2009

Chemists in France have developed a simple method to synthesise tricky ‘[3]rotaxane’ molecules for potential applications in intelligent materials and molecular machines. The method, which uses metal ions as a template, should be able to provide high yields of [3]rotaxane and other threaded species.

Rotaxanes are a class of compound that contain dumbbell-shaped molecules threaded through other, ring-shaped molecules. They have generated much interest over the past two decades because they can change shape in response to an external stimulus, an ability that lends them to intelligent materials and molecular machines in which the molecules themselves process information. […]

The rest of this article is available here.

Hidden photons to send secret signals through Earth

New ScientistJon Cartwright24 April, 2009

Published in New Scientist, 24 Apr 2009

If you shine a laser on the floor, where does the light go? With the right preparation, some of it might pop out at the other side of the world – an effect that could be exploited to transmit secret messages through the ground.

That is the conclusion of Andreas Ringwald at the German Electron Synchrotron (DESY) in Hamburg, and colleagues, who have explored the possibility of hypothetical particles called “hidden photons” (www.arxiv.org/abs/0903.5300). “If such particles exist, then we can use them to communicate,” says Ringwald. “It’s very simple.”

Hidden photons are a class of particles predicted by so-called supersymmetric extensions to the standard model of particle physics. Unlike normal photons, hidden photons could have a tiny mass and would be invisible because they would not interact with the charged particles in conventional matter. This means hidden photons would flit through even the densest materials unaffected. […]

The rest of this article is available here.

Particulate pollution cuts carbon dioxide, model shows

Physics WorldJon Cartwright22 April, 2009

Published in Physics World, 22 Apr 2009

Falling levels of aerosol pollution could make it much harder to curb the total amount of CO₂ in the atmosphere. That is the conclusion of climate researchers in the UK and Switzerland, who have found that pollution in the form of aerosol particles gives a dramatic boost to plants’ photosynthesis.

Large amounts of aerosols have been linked previously to a period of “global dimming” from the 1950s to the 1980s, when the amount of visible sunlight reaching the Earth’s surface was fractionally reduced. […]

The rest of this article is available here.

Dark matter could come naturally from quantum gravity

Physics WorldJon Cartwright21 April, 2009

Published in Physics World, 21 Apr 2009

A physicist in the US has calculated that dark matter — the unknown entity that makes up the vast majority of matter in the universe — could arise in a simple generalized quantum theory of gravity.

One of the most enduring problems of modern physics is that the theories of gravity and quantum mechanics do not readily mix. For over 90 years Einstein’s general theory of relativity has done a good job of describing gravity at large lengths scales, but it runs into trouble for all things very small, where quantum mechanics prevails. The trouble is in part due to the fact that quantum mechanics predicts the existence of fleeting “virtual” particles, which in Einstein’s equations cause awkward values of infinity. […]

The rest of this article is available here.

Isolated microbes survive for millions of years

Chemistry WorldJon Cartwright16 April, 2009

Published in Chemistry World, 16 Apr 2009

Researchers in the US and the UK have found microbes in the Antarctic that appear to have survived in isolation, without sunlight or new supplies of nutrients, for more than a million years. The discovery suggests that similar microbes could have survived the supposed ‘snowball Earth’ periods, when our planet may have been covered by ice, or could even exist elsewhere in the solar system.

Most organisms familiar to us rely in some fashion on energy generated by photosynthesis, a chemical reaction that uses carbon dioxide, water and sunlight. But not all organisms need photosynthesis: on the dark ocean floor some microbes survive on the oxidation of sulphides, for example, and some bacteria are known to survive inside rocks purely by reacting carbon dioxide with hydrogen. […]

The rest of this article is available here.

Ions keep their cool at crossroads

Physics WorldJon Cartwright15 April, 2009

Published in Physics World, 15 Apr 2009

Physicists in the US have created a junction through which single ultracold ions can pass without having their temperature raised. The junction is contained within a 2D ion trap and could be useful in building large-scale quantum computers.

Quantum computers, like classical computers, work by processing of bits of information. In classical computers such bits can take on only the values 0 and 1, but in quantum computers they can also take on “superpositions” of both 0 and 1. When many of these quantum bits or “qubits” are combined, a quantum computer can process them simultaneously. In principle, this would enable a quantum computer to work exponentially faster than its classical counterpart for certain operations — however many technical challenges must be overcome before practical quantum computers become a reality. […]

The rest of this article is available here.

Natural biomarker can signal cancer

Chemistry WorldJon Cartwright8 April, 2009

Published in Chemistry World, 8 Apr 2009

A florescent molecule naturally present in human tissue acts as an indicator of cancer, say bioengineers in the US, who have developed techniques to trace the molecule’s concentration, structure and position within a cell.

NADH, or nicotinamide adenine dinucleotide, is a molecule that resides mostly in a cell’s mitochondria, where the vital process of energy production takes place. During this process NADH works with enzymes to produce ATP, a molecule that transports chemical energy around the cell so that it can continue to function. At the onset of cancer, however, the enzymes become disabled, leaving unused NADH to build up. […]

The rest of this article is available here.

Gauging the matter-antimatter divide

Physics WorldJon Cartwright6 April, 2009

Published in Physics World, 6 Apr 2009

An international team of physicists has made the first theoretical estimation of the size of CP violation, a parameter that describes the difference between matter and antimatter. Their calculation matches experimental data, which suggests such data are typical of a fundamental framework and do not expose any underlying issues in the Standard Model of particle physics.

Besides energy, physicists think “stuff” comes in two forms: matter and antimatter. While most physicists believe that the Big Bang created equal amounts of both, the universe today is almost exclusively composed of matter and this discrepancy implies there should be a difference in behaviour between matter and antimatter. In the Standard Model of particle physics this is incorporated as a phenomenon known as charge–parity or “CP” violation. […]

The rest of this article is available here.