Calculations point to massive neutron stars

Physics WorldJon Cartwright

Published in Physics World, 15 Jan 2010

For a large star, death is a bit of a squeeze. Once its nuclear fuel is spent, its core collapses, sparking a dramatic supernova explosion that blasts away the outer layers. The body left is a cold, tightly packed sphere called a neutron star, which, if massive enough, makes the ultimate collapse to a black hole.

The huge pressures inside neutron stars mean that all electrons and protons have joined so only neutrons remain. Near the centre, according to theory, these neutrons sometimes decompose into a sea of quarks, or so-called strange quark matter. A recent theory implies that this matter could form a stable ground state of nuclear matter – suggesting the existence of standalone “quark stars”. […]

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Pulsar bursts move ‘faster than light’

Physics WorldJon Cartwright

Published in Physics World, 11 Jan 2010

Every physicist is taught that information cannot be transmitted faster than the speed of light. Yet laboratory experiments done over the last 30 years clearly show that some things appear to break this speed limit without upturning Einstein’s special theory of relativity. Now, astrophysicists in the US have seen such superluminal speeds in space – which could help us to gain a better understanding of the composition of the regions between stars.

Superluminal speeds are associated with a phenomenon known as anomalous dispersion, whereby the refractive index of a medium (such as an atomic gas) increases with the wavelength of transmitted light. When a light pulse – which is comprised of a group of light waves at a number of different wavelengths – passes through such a medium, its group velocity can be boosted to beyond the velocity of its constituent waves. However, the energy of the pulse still travels at the speed of light, which means that information is transferred in agreement with Einstein’s theory. […]

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Brain drain leads to more physicists heading to the US

Physics WorldJon Cartwright

Published in Physics World, 1 Jan 2010

If budgets are too tight at home, academics often flock abroad in what is known as a “brain drain”. But now a study by economists in the UK has revealed that elite physicists seem to be more mobile than ever. Having analysed the career paths of 158 of the world’s most highly cited physicists, Andrew Oswald of the University of Warwick and colleagues found that half do not now work in the countries where they were born (Economic Journal 119 F231). […]

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Large Hadron Collider becomes the world’s mightiest

Physics WorldJon Cartwright

Published in Physics World, 1 Jan 2010

It may have come online four years late but CERN’s Large Hadron Collider (LHC) has finally taken up the mantle as the world’s most powerful subatomic-particle smasher. That record was achieved on 9 December when members of the ATLAS experiment glimpsed by chance a handful of 2.36 TeV collisions during test circulations of two proton beams. Within a week the LHC had collided 50 000 protons at this energy, thus cementing a record that was previously held by the Tevatron at Fermilab in the US of 1.96 TeV. The breakthrough marks the beginning of the search for “new physics” at energies beyond the 2 TeV barrier. […]

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CDMS gives possible evidence for dark matter

Physics WorldJon Cartwright

Published in Physics World, 18 Dec 2009

For weeks physicists have been speculating whether the CDMS-II collaboration based in the US has detected the first direct evidence for dark matter, one of the universe’s most mysterious entities. Now the evidence is out in the open – although it’s not quite a strong as some had hoped.

In a preprint submitted to the arXiv server yesterday, the CDMS-II team claim to have detected two “events” that are characteristic of dark-matter constituents known as weakly interacting massive particles, or WIMPs. However, they point out that there is a one-in-four chance that these events could be background noise. […]

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Star wars

ProspectJon Cartwright

Published in Prospect, 16 Dec 2009

Will the EU’s “civilian” satellites also be used to guide bombs?

By 2013, if all goes to plan, a constellation of European satellites will have launched into the sky to form Galileo, a new instrument for satellite navigation. According to the European commission’s brochure, the €3.4bn (£3.1bn) system is “specifically designed for civil purposes”—including sat nav for cars, oil drilling, aviation and shipping. It will create 100,000 jobs, as well as €200bn of new markets in areas like transport, energy, finance and agriculture.

However, absent from this list is any mention of the military. Since the 1980s, the US global positioning system (GPS)—Galileo’s only fully operational counterpart—has helped co-ordinate the US military’s ground, sea and air operations. Today, GPS guides drones, smart bombs and cruise missiles, and is one of the key assets that makes the US a superpower.

Galileo began life in 1999 to provide satellite navigation independent from the US. Financed chiefly by EU civil budgets, the 30-satellite project was intended to be more accurate than GPS and, crucially, operate even if the US chose to switch off GPS signals at times of conflict.

At the start, Galileo’s military potential was also an open, if cautious, talking point. In 2001, the then President Chirac said the system would help “the development in Europe of a common security and defence identity.” Britain was a co-founder of that identity but, mindful of its special relationship with the US, it was less keen on a military role for Galileo, and by the following year public talk of military use disappeared. […]

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Higgs could reveal itself in dark matter collisions

Physics WorldJon Cartwright

Published in Physics World, 10 Dec 2009

For particle physicists analysing the first data from CERN’s Large Hadron Collider (LHC) in Geneva, it is the €4.3 bn question: is there a particle known as the Higgs, which endows all others with mass? But now a study suggests that there might be a far cheaper method of finding the answer – and gargantuan particle accelerators don’t get a look-in.

According to Marco Taoso of CERN and colleagues, the famed Higgs could be leaving its imprint in the light produced in collisions of dark matter, the substance believed by most scientists to make up the vast majority of the universe’s mass. In fact, the researchers think we could be seeing the tell-tale spectral signatures of the Higgs in this way within a year – so sooner, potentially, than the LHC unscrambles data on the elusive particle. […]

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Earth’s response to CO2 underestimated

Physics WorldJon Cartwright

Published in Physics World, 9 Dec 2009

Global warming resulting from slowly changing Earth systems could be up to 50% greater than previously thought, according to research by UK and US scientists. The study reinforces the notion that certain poorly understood systems such as ice sheets or vegetation are integral to accurately predicting future temperatures. It also paints an ever-bleaker outlook for our planet at a critical time when world leaders are gathering for a United Nations conference in Copenhagen to discuss practicable ways of mitigating climate change.

“If we want to build an agreement that is going to last for many, many centuries – so for our grandchildren’s grandchildren’s grandchildren’s grandchildren – then we need to be taking in these issues,” lead author Dan Lunt of the University of Bristol told physicsworld.com. […]

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Physics takes the wobble out of rowing

Physics WorldJon Cartwright

Published in Physics World, 3 Dec 2009

Every year, teams of rowers from Oxford and Cambridge universities sweep along the Thames river at close to 15 miles per hour in one of the world’s most famous boat races. In each boat, the oars lie alternately left and right to generate – one might assume – an even push. But is this the most effective rig?

Possibly not, according to John Barrow, a theoretical physicist at Cambridge. While not a rower himself, Barrow has produced a formula that shows which rigs will naturally travel in a straight line, without a finite mechanical moment that causes them to wiggle left and right. For an eight-oared boat there are several possible zero-moment rigs – and the traditional Oxbridge “eight” isn’t one of them. […]

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Reading between the lines

Chemistry WorldJon Cartwright

Published in Chemistry World, 1 Dec 2009

We will surely never solve all the mysteries of the universe. But, as Jon Cartwright reports, spectroscopy holds the key to unravelling many planetary secrets

Stars, planets and other gems in the night sky for so long seemed, both literally and metaphorically, worlds apart. Even the great 19th century French philosopher Auguste Comte, for all his novel perspectives on science, wrote that the internal make-up of ‘heavenly bodies’ would be ‘forever excluded from our recognition’. How wrong he was.

Today, there is no question of unravelling the make-up of objects in space. We know that elements found on Earth, namely hydrogen and helium, are also found on our sun. We know that the sun itself is just one of many trillions of stars, of which some are bigger, hotter, and contain heavier elements. We know the basic composition of planets in our solar system and that similar planets exist in systems throughout the galaxy. We even know a little about how these structures came to be, their dynamics, and how they are evolving in space and time. […]

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