Some liquids are very useful because their molecules act as tiny dipoles that can be aligned by electric or magnetic fields. Vehicle clutches, ink-jet printers and lubricants are among the applications that make use of these so-called dipolar fluids, which consist of micron-sized spherical particles suspended in a fluid. But to exploit the liquids further, […]
The standard model – developed by Pierre Weiss in 1907 – treats paramagnets as systems of non-interacting magnetic dipoles. The theory successfully describes the behaviour of paramagnets – materials that become weakly magnetized inside an applied magnetic field – but cannot account for ferromagnets. Ferromagnets are strongly magnetic even when there is no external field, […]
ESA’s director general Antonio Rodotà appointed the committee in March 2000. Carl Bildt, former Swedish Prime Minister and UN Envoy to the Balkans, Jean Peyrelevade, President of Crédit-Lyonnaisse, and Lothar Späth, CEO of German laser and optics company Jenoptik, were chosen to represent political, economic and industrial interests. The committee compares the annual US investment […]
Read article: Space to play a starring role in Europe’s future
Hints that the elusive Higgs boson – the holy grail of particle physics – had finally been sighted prompted CERN to extend LEP operation by five weeks. But in a race against time particle physicists failed to find convincing evidence to justify the continued operation of the accelerator. While the latest results from all four […]
Read article: End of the line for LEP
Ordinary experimental fluids are subject to effects like viscosity and can be difficult to manipulate. Durkin and Fajans therefore used a cylindrical column of magnetically confined electrons to simulate a perfect fluid. Electron density is equivalent to fluid vorticity, and this strongly magnetized electron column behaved as a vortex. The researchers used a photocathode to […]
Read article: Vortices get in a spin
A supernova explosion marks the death of a certain type of star. During the evolution of these stars, nuclear reactions take place at their cores, creating light elements like hydrogen and helium. Heavier elements are produced as the chain reaction proceeds, but iron is the heaviest element that it is energetically favourable for the star […]
Physics is well catered for within the week’s activities. A mock spaceship is part of an exhibition exploring the sun’s activity and how it affects us, and a film – Inspired by Nature – emphasises the link between naturally occurring phenomena and everyday products and appliances. An exhibition in Paris aims to demystify radioactivity by […]
Read article: A celebration of science
Atoms move through the crystal lattice of a solid by a process called diffusion. The atoms migrate by swapping places with ‘point defects’ such as vacancies – empty spaces in the lattice – and ‘interstitial’ atoms, which float between the regularly spaced atoms. In a semiconductor structure, a solid is doped with ‘foreign’ atoms that […]
Superfluids are among the most peculiar and counterintuitive of all materials. They have no viscosity, which allows an object travelling in a pure superfluid to move without friction. Similarly, they can flow effortlessly through narrow channels and pores that are virtually impermeable to conventional liquids. Superfluids are relatively rare and inaccessible, with only two known […]
Read article: Liquid hydrogen turns superfluid
Cosmologists have proposed that a mysterious substance called quintessence can explain why our universe is accelerating. But what is it made of?
Read article: Quintessence
