Newswise — The discovery that atoms are held together by looser forces than expected is the top physics story of the year, according to the editors of Physics News Update, the weekly bulletin of research news published by the American Institute of Physics.
Other top stories include evidence that dark energy, the hypothetical mechanism for accelerating the expansion of the universe, was present even in the early universe; and the discovery of two new elements, 118 and 116 (element 117 was not observed because of the way element 118 was created and because of the fact that it decayed almost immediately into element 116). A full list of top physics stories in 2006, along with links to descriptions of the top stories, and visuals in quite a few cases, can be found at the Physics News Update website (http://www.aip.org/pnu/2006/split/804-1.html)
To make their atomic discovery, Gerald Gabrielse and his colleagues at Harvard measured the magnetism of a single electron with unprecedented precision. The physicists held a single electron in the middle of a special trap for months, detecting its subtle movements under the influence of electric and magnetic fields. At the microscopic level electrons behave as if they are tiny bar magnets, and Gabrielse measured the strength of the electron's magnetism with an uncertainty of better than a part in a trillion. The new results were published in the journal Physical Review Letters in August 2006.
Then in a second paper the Harvard researchers combined their data with a fresh formulation of quantum electrodynamics (QED), the modern theory of the atom, to calculate a new value for the fine structure constant (denoted by the letter alpha), the pivotal parameter which sets the overall strength of the electromagnetic force. In effect alpha determines the intrinsic size of the force that holds atoms together and which governs all phenomena dealing with light, electricity, and magnetism. The new value of alpha has an uncertainty of less than one part per billion, and is the first major revision of alpha in 20 years. The new value shows that the energies that hold together atoms are smaller by a millionth of a percent—a lot of energy given the astronomical numbers of atoms in the universe. (For a fuller explanation see http://www.aip.org/pnu/2006/split/783 1.html or Physics Today magazine for August 2006).
The selection of this and other top stories was made on the basis of assessing news items published all year around in the American Institute of Physics (AIP) newsletter Physics News Update, edited by AIP science writers Phillip F. Schewe, Ben Stein, and Davide Castelvecchi.
Other prominent accomplishments for the past year include the sharpest object yet made; the best direct test of Einstein's E=mc^2 formula; the first direct measurement of turbulence in space; new measurements of the cosmic microwave background that help to sharpen cosmological numbers such as the age the flatness of the universe; the first study of matter-antimatter chemistry (involving antiprotons); advances in plasmonics, or "two-dimensional light" ; advances in the study of graphene, which is basically two-dimensional carbon; progress at several labs in modeling gravity wave transmissions from black hole mergers, the kinds of events which gravity-wave detectors such as LIGO or LISA are watching; and the 2006 Nobel prize in physics going to George Smoot and John Mather for their observations 15 years ago of the cosmic microwave background.
Physics News Update is a digest of physics news items arising from physics meetings, physics journals, newspapers and magazines, and other news sources. Subscriptions are free as a way of broadly disseminating information about physics and physicists. To subscribe, and view 16 years worth of physics news archives, visit the Physics News Update website at http://www.aip.org/pnu/
Celebrating its 75th anniversary this year, the American Institute of Physics (AIP) is a not-for-profit corporation chartered for the purpose of promoting the advancement and diffusion of the knowledge of physics and its application to human welfare.
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