Physics Today News Picks

Beams sent around LHC

2009-11-20T18:16:56Z

Physics Today: Updated: 2:38PM EST and 4:40PM EST: Scientists at the Large Hadron Collider (LHC), announced that they have sent a particle beam around the 27-kilometer collider.

"It’s great to see beam circulating in the LHC again," said CERN director general Rolf Heuer. "We’ve still got some way to go before physics can begin, but with this milestone we’re well on the way."

The LHC circulated its first beams on 10 September 2008, but suffered a serious malfunction nine days later. It has taken over a year repairing and consolidating the machine to ensure that such an incident cannot happen again.

"The LHC is a far better understood machine than it was a year ago," said CERN’s Director for Accelerators, Steve Myers. "We’ve learned from our experience, and engineered the technology that allows us to move on. That’s how progress is made."

The next important milestone will be low-energy collisions at 450 GeV, expected in about a week from now. Ramping the beams to high energy will follow in preparation for collisions at 7 TeV (3.5 TeV per beam) next year.

Recent coverage of the LHC by Physics Today can be found here.

Related news stories
Scientists at Cern hold their breath as they prepare to fire up the LHC The Guardian

A light touch on liquid droplets

2009-11-20T13:46:55Z

Nature: With microfluidic devices gaining prominence for many applications in chemistry and biology, the hunt is on to find ways of accurately controlling the motion of liquid droplets. In Angewandte Chemie, Antoine Diguet et al. describe a method for using light to trap and move oil droplets floating on an aqueous solution.

Russia restructures physics labs

2009-11-20T11:54:45Z

Science: Four of Russia's most prominent physics labs are to be merged into a new national research center. The institutes, which have languished in the post-Soviet era, have cautiously welcomed the raised profile the merger will bring.

But a different reform aimed at separating basic and applied research at one of the institutes—the Kurchatov Institute in Moscow, Russia's premier lab for nuclear energy research--has researchers up in arms.

The merger, announced in a presidential decree last month, will combine the Institute for High Energy Physics (IHEP) in Protvino, 100 kilometers south of Moscow; the B. P. Konstantinov Petersburg Nuclear Physics Institute (PNPI) in St. Petersburg; and two Moscow labs--the Institute for Theoretical and Experimental Physics (ITEP) and the Kurchatov. The reorganization is aimed at smoothing the path of innovations into industry, says Sergei Kiriyenko, chief of the nuclear energy agency Rosatom and one of the key officials behind the decree.

Khan documents confirms Chinese help in nuclear weapon research

2009-11-20T11:24:03Z

washingtonpost.com: In 1982, a Pakistani military C-130 left the western Chinese city of Ürümqi with a highly unusual cargo: enough weapons-grade uranium for two atomic bombs, and a blueprint of how to build one say accounts written by the father of Pakistan's nuclear weapons program, Abdul Qadeer Khan.

Khan is currently under house arrest.

The uranium transfer was part of a broad-ranging, secret nuclear deal approved years earlier by Chinese premier Mao Zedong and Prime Minister Zulfikar Ali Bhutto.

US officials say they have known about the transfer for decades and once privately confronted the Chinese—who denied it—but have never raised the issue in public or sought to impose direct sanctions on China for it.

The transfer also started a chain of proliferation in which Khan's nuclear smuggling network shared related Chinese design information with Libya and possibly Iran.

China's refusal to acknowledge the transfer and the unwillingness of the United States to confront the Chinese publicly demonstrate how difficult it is to counter nuclear proliferation writes the Washington Post's R. Jeffrey Smith and Joby Warrick.

A new way of ranking scientists

2009-11-19T20:38:37Z

APS Physics: Most metrics of a scientist’s impact in a field, like the h-index, rely primarily on the number of times his or her papers have been cited, and can miss the more subtle ways that knowledge and credit for this research spread among scientists.

Filippo Radicchi, Santo Fortunato, Benjamin Markines, and Alessandro Vespignani are instead proposing a way to rank scientists that reflects the diffusion of scientific credit in time.

Their method, based on an algorithm similar to Google’s PageRank, takes into account several nontrivial effects such as the fact that being cited by an important author has more influence than being cited by one who is less well known.

Fermilab pushes muon collider

2009-11-19T20:12:10Z

Nature News: Last week, US particle physicists staked their claim in a daring new venture to develop the next generation of accelerators by proposing the world's first muon collider.

The collider could overtake two more-mature concepts, each of which plan to smash together electrons and positrons that have been accelerated through long, straight tunnels.

But some physicists at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, are concerned about the expense and feasibility of the linear colliders, and question whether they would push the boundaries of physics beyond what the Large Hadron Collider is expected to achieve.

They are now trying to rally enthusiasm for a collider that smashes muons, a particle that is about 200 times more massive than the electron.

Temperature spikes in ancient Antarctica

2009-11-19T15:23:32Z

Physics Today: A new study of Antarctica's past climate reveals that temperatures during the warm periods between ice ages (interglacials) may have been higher than previously thought.

The findings, reported in Nature by scientists from the British Antarctic Survey (BAS), the Open University and University of Bristol could help us understand more about rapid Antarctic climate changes.

The conclusions come the latest analysis of ice core records that suggests that Antarctic temperatures may have been up to 6°C warmer than the present day. (see image left. This Slice of ice core from Berkner Island, was dug up from a depth 120 meters below the surface. Trapped air bubbles (an archive of the past atmosphere) are visible in the ice. Photo credit: BAS)

Previous analysis of ice cores has shown that the climate consists of ice ages and warmer interglacial periods roughly every 100,000 years.

This new investigation shows temperature 'spikes' within some of the interglacial periods over the last 340,000 years. This suggests Antarctic temperature shows a high level of sensitivity to greenhouse gases at levels similar to those found today.

"We didn't expect to see such warm temperatures, and we don't yet know in detail what caused them," says Louise Sime of the British Antarctic Survey and the lead author of the author. "But they indicate that Antarctica's climate may have undergone rapid shifts during past periods of high CO2."

During the last warm period, about 125,000 years ago, sea level was around 5 meters higher than today.

"If we can pin down how much warmer temperatures were in Antarctica and Greenland at this time, then we can test predictions of how melting of the large ice sheets may contribute to sea level rise," says BAS's Eric Wolff.

World's largest radio telescope network goes live

2009-11-18T21:38:56Z

Space.com: The world's largest collection of radio telescopes is being tied together for 24 hours starting today to observe more than two hundred energetic galaxies known as quasars.

During those 24 hours, 35 telescopes on all seven continents will observe 243 distant quasars in an effort to improve the precision of the reference frame scientists use to measure positions in the sky.

The US climate debate in the 18th Century

2009-11-18T21:10:05Z

NYTimes.com: The controversy over the direction and temperature of the US climate has existed for hundred of years.

Benjamin Franklin understood climatic forcing factors better than anyone, surmising in a 1763 letter to Ezra Stiles that "cleared land absorbs more heat and melts snow quicker."

Franklin, later surmised (correctly) that a prevailing haze over parts of North America and northern Europe was associated with the eruption of the Laki volcano in Iceland in June 1783, and was possibly the source for the exceptional chill experienced in the winter of 1783-84 in the colonies.

In the 1780s, Thomas Jefferson opined in his "Notes on Virginia" that "both heats and colds are become much more moderate within the memory even of the middle-aged."

Noah Webster quarreled with Jefferson, insisting that he relied too heavily on the memories of "elderly and middle-aged people" for his observation that the climate had moderated, a debate that was not resolved in Jefferson's favor for years until more meticulous climate observations had been made.

Says meteorologist Ben Gelber:

Now we have satellites monitoring high-latitude snow cover, thinning sea ice and deep-layered atmospheric temperature increases, coupled with ground observations revealing the disappearing snows of Kilimanjaro (85 percent ice loss since 1912) and many other glaciers.
The wealth of data now at our disposal, enhanced by high-resolution computer models that pioneer climatologists would have craved, has, curiously, not turned down the thermostat on the centuries-old global climate change debate, quite likely because the stakes are so much higher.

Spain to get molten salt solar power plant

2009-11-18T20:21:49Z

CNET News: SolarReserve and Preneal have garnered the necessary permit to build a 50-megawatt thermal-solar plant in Spain that will use molten salt to store and release solar energy.

The project will be built in Alcazar de San Juan, a town about 110 miles south of Madrid.

Ericsson R&D pulls out of Coventry

2009-11-18T12:08:44Z

The Register: Ericsson is pulling out of its R&D facility at Ansty Park, in the UK, jeopardizing 700 jobs in the process despite only moving in six months ago.

Earth heading for 6 degrees of warming

2009-11-17T19:45:55Z

BBC News: Average temperatures across the world are on course to rise by up to 6°C without urgent action to curb CO₂ emissions, according a new analysis.

Related news story
Global temperatures will rise 6C by end of century, say scientists The Guardian

Using noise to store data

2009-11-17T19:39:17Z

Science News: Studying with the radio on may not be the best way to remember what you've read. But scientists have now built a data storage device whose memory gets a boost from noise.

The device can store one bit of information, such as a 0 or a 1, only when surrounded by electronic noise, which is normally a problem in computer circuits.

"If you remove the noise, it doesn't store the bit at all," says Diego Grosz of the Instituto Tecnológico de Buenos Aires, a coauthor of the study.

Holes that block light

2009-11-17T19:31:48Z

ScienceNOW: The way light moves, with its fixed speed and its ability to act like either a wave or a particle, often leads to some of the most curious paradoxes of physics. A new one has just been found: Make holes in a film of gold so thin that it's already semitransparent, and less light gets through.

Star likely to become a Type 1a supernova

2009-11-17T19:16:27Z

Physics Today: A white dwarf star called V445 in the constellation of Puppis, that is digesting its closest neighbor, is a prime candidate to explode as a Type Ia Supernova, ejecting a large quantity of matter into space.

V445 Puppis has been under a two-year observation by the European Southern Observatory's Very Large Telescope. The star was discovered by a amateur Japanese astronomer when it became visible as a nova in November 2000. It is the only nova appearing that has no hydrogen and provides the first evidence for an outburst on the surface of a white dwarf dominated by helium.

"This is critical, as we know that Type Ia supernovae lack hydrogen and the companion star in V445 Pup fits this nicely by also lacking hydrogen," says Danny Steeghs, from the University of Warwick, and one of the key team members observing the star. A earlier paper by astronomers Mariko Kato and Izumi Hachisu that modeled the star's behavior suggested as much.

The images (above. Credit: ESO) show a bipolar shell, initially with a very narrow waist, with lobes on each side. Two knots are also seen at both the extreme ends of the shell, which appear to move at about 30 million kilometers per hour.

The shell—unlike any previously observed for a nova—is itself moving at about 24 million kilometers per hour. A thick disc of dust, which must have been produced during the last outburst, obscures the two central stars.

"As the white dwarf feeds on its companion, the captured gas accumulates on its surface until thermonuclear reactions begin, causing a massive explosion which ejects matter out into space at phenomenal speeds," says co-researcher Tim O'Brien, of the Jodrell Bank Centre for Astrophysics in the UK.

If the white dwarf continues to gain mass, "it will eventually reach a point where it will be ripped apart in a titanic supernova explosion and its cycle of outbursts will come to an end," adds O'Brien.

Type Ia supernovae are critical for studies of dark energy and for measuring distances in the universe.

V445 Puppis is over 10,000 times brighter than the Sun, implying that it is near its fatal limit to turn into a supernova.

Patrick Woudt, from the University of Cape Town, and the lead author of an Astrophysical Journal paper describing V445 Puppis says that "one of the major problems in modern astrophysics is the fact that we still do not know exactly what kinds of stellar system explode as a Type Ia supernova" which is "rather embarrassing."

"Whether V445 Puppis will eventually explode as a supernova, or if the current nova outburst has pre-empted that pathway by ejecting too much matter back into space is still unclear," Woudt adds. "But we have here a pretty good suspect for a future Type Ia supernova."