JON CARTWRIGHT – Page 53 – & THREE QUARKS EDITORIAL

River deltas hint at ancient Martian ocean

NatureJon Cartwright13 June, 2010

Published in Nature, 13 Jun 2010

Planetary geologists in the United States have analysed data that suggest Mars was once home to a huge ocean of water, covering nearly one-third of its surface. Their evidence, a ring of dry river deltas and valleys all at a similar elevation, adds weight to the idea that the red planet once supported an Earth-like water cycle.

Hints that an ocean once occupied the northern lowlands of ancient Mars first arose in the late 1980s. Scientists examining pictures of the surface claimed to recognize extensive shorelines and vast networks of river valleys and outflow channels feeding in the same direction. Other researchers used thermal physics to imply that such networks could only have been carved by a complete water cycle, fuelled by one or more huge bodies of water. […]

The rest of this article is available here.

Mystery of Saturn’s midget moons cracked

NatureJon Cartwright9 June, 2010

Published in Nature, 9 Jun 2010

For decades, researchers have puzzled over the origin of Saturn’s baby moons. According to conventional models, these moons are so small that collisions with comets should have blown them to pieces long ago. Now a group of researchers in France and Britain think they have the answer — and it lies in the planet’s icy rings.

Accepted theory says that the giant planets, and their moons, slowly accreted out of a gaseous ‘protoplanetary disk’ around the Sun some 4.5 billion years ago. Yet Saturn’s baby moons never quite fitted this picture. At less than 50 kilometres across, they ought to have been destroyed by comets over that period. And over time, moons tend to recede from the planets they orbit, as indeed our Moon is receding from Earth. But Saturn’s moons are in such a close orbit that they would have had to have formed virtually inside the giant planet. […]

The rest of this article is available here.

Laser tracks electrons in molecules

Chemistry WorldJon Cartwright9 June, 2010

Published in Chemistry World, 9 Jun 2010

An international team of researchers has used attosecond laser pulses to track the movement of electrons in molecules for the first time. The breakthrough suggests that attosecond lasers will soon enable scientists to address problems in chemistry and biology, which until now were too complex for attosecond science.

At just 10^-18 seconds, an attosecond is to one second what one second is to the age of the universe. For almost a decade scientists have been able to create laser pulses this brief, in doing so opening up a new level in atomic probing. Unlike femtosecond pulses, which can only ‘freeze’ the position of atoms and molecules, attosecond pulses can freeze the position of the orbiting electrons themselves. […]

The rest of this article is available here.

Does dark matter come in two types?

Physics WorldJon Cartwright8 June, 2010

Published in Physics World, 8 Jun 2010

Contradictory results from experiments searching for dark matter can be resolved if the elusive dark stuff is made up of two types of particle, according to physicists in the US.

The new theory could clear up a mystery that came to light in 2008, when the PAMELA collaboration released one of the strongest pieces of evidence yet for the direct detection of dark matter – a substance thought to make up over 80% of the universe’s matter. PAMELA saw a bump in the abundance of cosmic anti-electrons, also known as positrons, thought to be generated as dark-matter particles annihilate. But there was no concordant signal for anti-protons, which should also be generated by the annihilation. […]

The rest of this article is available here.

LED entangles light at the flick of a switch

NatureJon Cartwright2 June, 2010

Published in Nature, 2 Jun 2010

UK physicists have made a key step towards practical quantum computing: they have created a light source that fires entangled photons when triggered by an electric current.

Quantum computers exploit the inherent uncertainties of quantum physics to perform calculations much faster than computers currently in use. Whereas conventional ‘bits’ of information take only the values zero or one, quantum bits, or ‘qubits’, exist in a fuzzy superposition of both. In theory, this ambiguity allows any number of qubits to be lumped together or ‘entangled’ and processed in parallel, so that a huge number of calculations can be made at once. […]

The rest of this article is available here.

Quirky particles could explain universe’s missing mass

Physics WorldJon Cartwright1 June, 2010

Published in Physics World, 1 Jun 2010

For over 70 years astrophysicists have speculated what might compose the missing dark matter that seems to make up over 80% of all mass in the universe. The typical candidates are fundamental entities known as weakly interacting massive particles, or WIMPs, but new research suggests something more peculiar would better fit the bill.

According to Kathryn Zurek of the University of Michigan and colleagues, “quirky composite dark matter” could explain the universe’s missing mass, but would be free of some of the usual problems associated with conventional WIMP dark matter. “People are becoming more and more open to more complex theories of dark matter,” says Zurek. […]

The rest of this article is available here.

Light sparks new approach to data storage

Chemistry WorldJon Cartwright23 May, 2010

Published in Chemistry World, 23 May 2010

Chemists in Japan have created the first material that can undergo a photoreversible transition from metal to semiconductor. The breakthrough heralds applications in ultra high density data storage, with 500 times the density of a Blu-ray disc.

The past decade has seen a growing interest in ways to switch the physical properties of matter. Temperature and pressure can both turn materials, say, from insulators to metals, or from non-magnetic to magnetic, but they are difficult to control in complex memory devices. As a result, researchers have been looking at photoinduced phase transitions, for which the key stimulus is laser light. Recently, laser light has been shown to switch certain materials from amorphous to crystalline, from neutral to charged, or from one colour to another. […]

The rest of this article is available here.

Quantum cryptography system hacked

Physics WorldJon Cartwright20 May, 2010

Published in Physics World, 20 May 2010

It is supposed to be absolutely secure – a means to transmit secret information between two parties with no possibility of someone eavesdropping.

Yet quantum cryptography, according to some engineers, is not without its faults. In a preprint submitted late last week to arXiv, Hoi-Kwong Lo and colleagues at the University of Toronto, Canada, claim to have hacked into a commercial quantum cryptography system by exploiting a certain practical “loophole”. So does this mean high-profile users of quantum cryptography – banks and governments, for example – are in danger of being eavesdropped after all? […]

The rest of this article is available here.

DNA robots move with purpose

Physics WorldJon Cartwright12 May, 2010

Published in Physics World, 12 May 2010

Two independent teams in the US have made DNA robots mimic the protein motors in our bodies – be it walking without help along predefined routes or taking cargo from A to B.

The experiments, which are the first to truly combine advances in our knowledge of DNA structure and dynamics, suggest that nanorobots could soon be performing autonomous, useful tasks. […]

The rest of this article is available here.

Unconventional thinkers or recklessly dangerous minds?

Times Higher EducationJon Cartwright6 May, 2010

Published in the Times Higher Education, 6 May 2010

Aids denialism is estimated to have killed many thousands. Jon Cartwright asks if scientists should be held accountable

In late 1996, Robert C, a social worker living in New York, was diagnosed as HIV-positive. At first he followed his doctor’s advice and collected his prescription antiretrovirals, which stall the disease’s progression. But he never took the drugs. Instead, encouraged by a series of articles in the US magazine Spin, he did nothing.

For a few years, everything was fine. Then, in February 2003, Robert spotted what looked like a blood blister on the back of his calf. That, he would later discover, was Kaposi’s sarcoma, a cancer known to be triggered by Aids. Soon thereafter, he noticed that his tongue was growing patches of white fur. That would turn out to be hairy leukoplakia, an infection also strongly linked with Aids. By May that year, he had contracted Aids-related pneumonia, forcing him to revisit a surgery. But the doctor unknowingly prescribed treatment for common pneumonia: Robert refused to admit that he had HIV.

Only in January 2004, having attempted suicide to escape a nervous breakdown, did Robert finally make it into hospital and receive the drugs that would save him from death. “I still have these moments when I have to remind myself that I’m not in that world any longer,” he says now, clear of Aids for almost six years.

Robert is one of many who, in the wake of a traumatic diagnosis, have succumbed to the belief that HIV does not cause Aids. It is an idea circulated by so-called Aids denialists, who claim – contrary to the overwhelming scientific evidence – that HIV is harmless, or doesn’t exist, and that the true causes of Aids are either certain “lifestyles” or antiretrovirals (ARVs) themselves. A recent survey of gay and bisexual men in four US cities found that 45 per cent think that HIV does not cause Aids, and more than 50 per cent believe that HIV drugs do more harm than good. In South Africa, policies stemming from Aids denialism led to an estimated 340,000 deaths. The shocking toll is prompting many scientists and activists to ask: who should be held accountable? […]

The rest of this article is available here.