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Physics World Digest: April 2002 edition

March 28, 2002

Antique dealers turn to physics
If you`ve ever wondered if that old Chinese vase in your loft is a genuine antique, physicist Doreen Stoneham could have the answer. She has set up a company - Oxford Authentication - that uses "thermoluminescence" to distinguish a real T`ang dynasty ceramic from a fake. When a tiny amount of material from the antique is removed and fired in an oven, the ceramic releases a small - but measurable - amount of light. The brightness of the light gives a measure of the sample`s age. Stoneham`s company tests over 3000 samples every year - and is even getting wise to forgers who are trying to beat the system by inserting pieces of genuine porcelain into fake antiques. (p. 23)
Contact: Doreen Stoneham, Oxford Authentication, Wantage, UK (tel. +44 (0)1235 770 998; fax +44 (0)1235 771 021)

Ball lightning comes down to Earth
Believe it or not, but there are over 10,000 scientific reports into the weird phenomenon of "ball lightning". Once studied by Benjamin Franklin, these slow-moving balls of light are usually about 30 centimetres across and are occasionally seen at ground level during a storm. Two park rangers in the Australian outback in 1987 even saw a stationary glow that was 100 metres across. John Abrahamson from the University of Canterbury believes that ball lightning is not caused by extraordinary new physical processes - as some have speculated - but by the oxidation of tiny particles of silicon a millionth of a millimetre in diameter. He thinks that the particles are formed when the intense heat of a lightning strike causes carbon and silicon oxide in the soil to react with one another. (p. 22)
Contact: John Abrahamson, Department of Chemical and Process Engineering, University of Canterbury, New Zealand (tel. +64 3 364 2318; fax +64 3 364 2063; e-mail j.abrahamson@canterbury.ac.nz)

Ted Postol: exposing the failures of missile defence
Ted Postol is a thorn in the side of the US military-industrial complex. In 1997 the Massachusetts Institute of Technology physicist cast doubt on an official test that had been carried out to monitor a new US antiballistic-missile system. The Pentagon said that the test had succeeded, but Postol argued that the real results had been covered up. He also claimed that a panel of experts charged with investigating the case were wrong. Physics World profiles Postol, who says he feels "extremely comfortable that [he is] doing the right thing". (p. 10)
Contact: Ted Postol, Security Studies Program, Massachusetts Institute of Technology, US (tel. +1 617 2538077; e-mail at postol@mit.edu)

What physicists think of philosophy
When Physics World ran a special poll last year to find out what physicists think of philosophy, over 500 readers replied. Physicists were presented with a list of items - such as atoms, emotions and imaginary numbers - and asked to say whether they regarded them as "real" or not. Some 36% of physicists, for example, think that colours are not real, while just 76% think that mass is real. Robert P Crease analyzes the results and finds that while many physicists adhere to a brand of philosophy known as "critical realism", a sizeable fraction have very different views. (p. 15)

Contact: Robert P Crease is in the Department of Philosophy, State University of New York at Stony Brook, and historian at the Brookhaven National Laboratory, US, e-mail rcrease@notes.cc.sunysb.edu

Cool stuff: Fermi gases
When Eric Cornell, Carl Wieman and Wolfgang Ketterle were awarded last year`s Nobel Prize for Physics, they won the prize for creating and studying "Bose-Einstein" condensates - a new form of matter consisting of atoms cooled to a whisker above absolute zero. Their research centred on "bosons" - atoms in which the total number of protons, neutrons and electrons is even. Now, as Deborah Jin explains, physicists have extended their work to create ultracold gases made from "fermions" - atoms in which the total number of protons, neutrons and electrons is odd. Their work is revealing the fundamental differences between the two types of particles at the quantum level. (p.27)
Contact: Deborah Jin, University of Colorado, US (tel. +1 303 492 0256; fax +1 303 492 5235; e-mail jin@jilau1.colorado.edu)

Who really discovered Snell`s law?
Anyone who studies physics at school will sooner or later come across "Snell`s law". Named after the Dutch scientist Willebr'¸rd Snell (1591-1626), the law links the angle that a beam of light enters a block of glass or other object with the angle at which it emerges. But new research by the French scholar Roshdi Rashed reveals that Snell does not deserve all the credit. As John Dudley explains, it turns out that the origin of the law can be traced back to a 10th-century Islamic scholar Abu Said al-Ala Ibn Sahl. (p. 64)
Contact: John Dudley, Université de Franche-Comté, Besan'§on, France (tel. +33 3 81 66 64 16; fax +33 3 81 66 64 23; e-mail john.dudley@univ-fcomte.fr)

Also in this issue:
Bubble fusion: fact or fiction? (p. 5 & 13); Paris meeting sets agenda for equality(p. 6); QinetiQ eyes up the potential of MEMS (p. 8); Cambridge Display Technology: from polymers to profits (p. 9); Qunatum computers get real. (p. 21); Return of the magnetic resonance (p. 24); Novel quantum order in the ruthenates (p. 33); Spintronics: exploiting the spin of electrons (p. 39); Institute tackles the teacher shortage (p. 50)

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