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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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 […]
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. […]
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 […]
Thomas Kuhn is famous for writing the surprise best-seller The Structure of Scientific Revolutions. Who would have thought that a book published in 1962 on the history of science would turn out to be what Steve Fuller claims is the best-known academic book of the second half of the 20th century? So well known is […]
