At the turn of the year, APS News staff looked back at the news about physics and physicists that made headlines in 2010. These top ten selections, arranged roughly chronologically, are not necessarily the stories that will prove the most significant or long-lasting, but they are a fair sample of what the media reported, and the public digested, over the previous twelve months.
Researchers at the Relativistic Heavy Ion Collider at Brookhaven National Lab in Upton, New York announced at the annual APS April Meeting (held in February in 2010) that they had confirmed the highest temperature ever recorded, about 4 trillion degrees Celsius. By colliding gold ions together at 370 MeV per nucleon, members of the PHENIX collaboration at the lab created a sample of the exotic state of matter known as quark-gluon plasma, the first to exist since a few microseconds after the Big Bang. Even more tantalizingly, during their work, the team reporter tiny localized “bubbles” of asymmetry in the charge separation of particles ejected from collisions, which could potentially hold clues to explain matter’s ultimate triumph over antimatter in the primordial universe.
In March researchers at the University of California, Santa Barbara announced a remarkable crossover between the quantum and classical worlds. Andrew Cleland and John Martinis designed a small metal paddle made of a semi-conducting material, just visible to the naked eye. They cooled it down to its ground state, and then raised its energy by a single quantum, getting it to vibrate in both its ground state and its second lowest energy state at the same time. The achievement has been heralded as the first time the motions of a macroscopic object can only be described by the by the laws of quantum mechanics.
Physicists had a lot to do with helping to resolve the Gulf Oil spill last April. The Secretary of Energy, physicist Steven Chu, was a major figure on the team working to find a way to stem the gushing oil. Additionally, the Flow Rate Technical Group, composed largely of experts in fluid dynamics, was formed to estimate how much oil was spewing out of the damaged underwater pipe. The group used techniques like particle image velocimetry taken from videotape of the gushing pipe, pressure and flow readings and aerial photography to figure out the total amount. All together the group estimates that about 200 million gallons of oil spilled into the Gulf of Mexico, a figure that BP disputes.
In July, astronomers announced the discovery that a new star, R136a1 in the NGC 3603 star cluster, tipped the scales at 265 solar masses, the biggest star ever seen. Brighter than 10 million suns, R136a1 calls several existing models of star formation into question. Up to this point, it had been widely believed that stars couldn’t form with a mass greater than about 150 solar masses. Astrophysicists are looking back at models for insights as to whether such a monster could form by itself, or if several stars had to merge early in their stellar lives.
In September, physicists at NIST announced that they were able to measure relativistic effects at a human scale using newly developed atomic clocks based on the vibrations of aluminum ions. The clocks are the most accurate ever devised, and represent the beginning of a new generation of atomic clocks, as they operate using laser light rather than the current standard of microwaves on cesium atoms. These new aluminum clocks were sensitive enough to detect the time dilation caused by different gravitational forces felt just 33 centimeters apart. Unsurprisingly, the amount by which the clocks varied was minuscule. The team estimates it to be no more than a difference of about 90 billionths of a second over a person’s average lifetime of 79 years, but it’s the first time that devices have been able to measure relativistic effects on a human scale.
Announced in October, this year’s Nobel Prize for physics went to Andre Geim and Konstantin Novoselov, both at the University of Manchester in the United Kingdom, for their work isolating graphene. Graphene has quickly become one of the hottest and most studied subjects in condensed matter since Geim and Novoselov first published their paper in Nature in 2004. In it they described how they were able to first isolate the one-atom-thick lattice of carbon atoms by painstakingly using scotch tape to peel off thinner and thinner layers of graphite. Graphene promises to lead a revolution in how nearly everything is made because it is the strongest known material but still flexible and lightweight, transparent, as good a conductor of electricity as copper, and perhaps the best known conductor of heat.
In early November astronomers at the Harvard-Smithsonian Center for Astrophysics, using observations taken from the Fermi Gamma-ray Space Telescope, announced the surprising discovery of two gigantic bubbles or lobes of gamma-ray-emitting gas surrounding the Milky Way Galaxy. Each lobe is the size of a small galaxy, about 25,000 light-years across. The source of the bubbles is not clear. They might be the remnants from a period of star formation in the galaxy’s distant past or they are the leftovers of a prehistoric eruption from the supermassive black hole that lurks at the galaxy’s center. The two bubbles remained hidden until now in a veil of high-energy gamma ray fog, even though they take up more than half of the night sky.
In November, researchers at CERN announced they were able to capture atoms of antimatter in a magnetic trap. The ALPHA team, led by Jeffrey Hangst of the University of Aarhus in Denmark, were able to hold onto 38 anti-hydrogen atoms for one sixth of a second. Teams at the lab have been producing anti-hydrogen atoms since 2002 by combining antiprotons and positrons, but this is the first time that the antimatter atoms didn’t combine with regular matter and annihilate within microseconds.
Iranian physicists have become the targets of repeated assassination attempts. In November, coordinated attacks killed Majid Shahriari and critically wounded Fereydoon Abbasi. This followed an attack in January when quantum physicist Masoud Alimohammadi was killed when a motorbike rigged with explosives detonated outside his home. It is unclear if the January attacks and the November attacks are connected. It is widely believed that Alimohammadi was a political moderate, while the Iranian regime was quick to blame foreign enemies of the state for the November attacks. It has been alleged that the two physicists targeted in November’s attacks were involved with Iran’s nuclear program.
Astronomers have observed a strange anomaly in the velocity and trajectories of Pioneer 10 and 11, launched in 1972 and 1973 respectively. They’re slowing down, and each year the crafts experienced an unexplained decelleration of about 8.74 x 10-10 m/s2 per year, an eye-catching rate because it’s close to the product of the Hubble constant multiplied by the speed of light. Numerous theories have been put forward to explain the anomaly, ranging from observational errors to a fundamental reassessment of the nature of gravity. However in late December, word leaked out that Slava Turyshev, a researcher at NASA’s Jet Propulsion Laboratory and Viktor Toth, a software developer from Canada, are getting ready to publish a report that should conclusively solve the Pioneer problem. They’re being guarded on the precise results, but they’ve painstakingly constructed a complete 3D model of every surface of the spacecrafts along with heat recoil force data for all of the surface materials. It’s expected that when they finally release their data, this recoil force should make up almost all, if not all, of the discrepancy.