Top marks awarded to Chinese students
China swept the board at a recent international competition for physics students. Edwin Cartlidge went along to find out more
Author archive
Strength is weakness on the Internet
In a ‘scale-free’ network of many interconnected nodes, like the Internet, most of the nodes are connected to a relatively small number of other nodes. Only a very small minority have a large number of connections. It is therefore extremely unlikely that randomly failing links would have a catastrophic effect on the whole network. In […]
Tau neutrino identified at last
The DONUT team fired an intense beam of neutrinos, which they expected to contain tau neutrinos, at a target consisting of iron plates with layers of emulsion sandwiched between them. One in a million million tau neutrinos interacted with an iron nucleus to produce a tau lepton, which subsequently decayed leaving a characteristic track in […]
Laser smashes light-speed record
Special relativity prevents any object with mass travelling at the speed of light, and the principle of causality – the notion that the cause comes before the effect – is used to rule out the possibility of superluminal (faster-than-light) travel by light itself. However, a pulse of light can have more than one speed because […]
Microscopy: two lasers are better than one
Stefan Hell and co-workers at Gottingen have adapted a technique known as fluorescence microscopy. In this form of microscopy the specimen is irradiated at a wavelength which excites either natural or artificially introduced fluorescent molecules known as fluorochromes. The sample is then studied through a filter that transmits at the fluorescence wavelength, but absorbs light […]
Sir Mark Oliphant dies
Oliphant was born in Adelaide in 1901 and attended the local university before going to Cambridge University in 1927, where he worked on nuclear physics experiments with Ernest Rutherford. In 1937 he was elected a fellow of the Royal Society and moved to Birmingham University to be head of department. During his time at Birmingham […]
Nuclei show their soft side
Helium-6 is a typical neutron-skin nucleus, with two of the neutrons forming a “skin” around the alpha-particle core. Different types of dynamics are possible in such nuclei. In the soft dipole resonance observed by the Japanese group, the alpha particle and neutrons oscillate in opposite directions. In a so-called giant dipole resonance, on the other […]
Superconducting gains
The device has three electrodes: a niobium injector electrode; a common electrode that consists of a layer of niobium and a layer of aluminium; and a niobium detector electrode. The electrodes are separated by insulating barriers, or junctions, through which current can pass by quantum tunnelling. At the operating temperature of 4.2 Kelvin, all the […]
Laser control of X-ray output
In harmonic generation a short pulse of intense radiation is focussed into a gas of atoms. The laser-atom interactions are highly nonlinear, and a number of the input photons effectively combine to generate a single output photon with a correspondingly higher energy and shorter wavelength. In most experiments a range of so-called harmonics is produced. […]
What’s hot – the ten best-selling physics books
Having just scooped this year’s Aventis Prize for Science Books, Brian Greene’s The Elegant Universe shot back to the top of the best-seller list of physics books for the month of May at Amazon.co.uk, the on-line bookstore. First published over a year ago, Greene’s masterful introduction to string theory was praised by the chairman of […]
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