Physics World

Ever since antiquity, attempts have been made to reduce an apparently complex reality to a few elementary building blocks from which everything else is constructed. This project – now called reductionism – has a long history of failures. One example is the 200-year-long attempt to describe all physical processes in terms of mechanics, such as James Clerk Maxwell's mechanical models of the electromagnetic field. Another is Hermann Weyl's failed attempt to unify electromagnetism and gravity in a single theory shortly after Einstein had introduced special relativity.

Nature abounds with phase transitions. The boiling and freezing of water are everyday examples of phase transitions, as are more exotic processes such as superconductivity and superfluidity. The universe itself is thought to have passed through several phase transitions as the high-temperature plasma formed by the big bang cooled to form the world as we know it today.

Quantum dots are man-made "droplets" of charge that can contain anything from a single electron to a collection of several thousand. Their typical dimensions range from nanometres to a few microns, and their size, shape and interactions can be precisely controlled through the use of advanced nanofabrication technology.

Physicists will find it shocking, but there are plenty of people around the world who genuinely believe the Earth is flat. Rachel Brazil explores why such views are increasingly taking hold and how the physics community should best respond

The article "A brief history of the double-slit experiment" (September 2002 p15; correction October p17) describes how Claus Jönsson of the University of Tübingen performed the first double-slit interference experiment with electrons in 1961. It then goes on to say: "The next milestone – an experiment in which there was just one electron in the apparatus at any one time – was reached by Akira Tonomura and co-workers at Hitachi in 1989 when they observed the build-up of the fringe pattern with a very weak electron source and an electron biprism (Am. J. Phys. 57 117–120)."

Superconducting magnets inside a fusion reactor will experience conditions that aren't seen anywhere on Earth. Materials scientists Susie Speller and Chris Grovenor are trying to predict how long these components can last in this extreme environment.

Why would anyone still want to study a physical phenomenon that was discovered in the 1930s, explained in the 1960s and has been the subject of numerous reviews since the 1970s? Although the Kondo effect is a well known and widely studied phenomenon in condensed-matter physics, it continues to capture the imagination of experimentalists and theorists alike.

Surely, after 62 years, we should have an exact formulation of some serious part of quantum mechanics? By 'exact' I do not of course mean 'exactly true'. I mean only that the theory should be fully formulated in mathematical terms, with nothing left to the discretion of the theoretical physicist...until workable approximations are needed in applications. By 'serious' I mean that some substantial fragment of physics should be covered. Nonrelativistic 'particle' quantum mechanics, perhaps with the inclusion of the electromagnetic field and cut-off interaction, is serious enough. For it covers 'a large part of physics and the whole of chemistry' (P A M Dirac 1929 Proc. R. Soc.A 123 714). I mean too, by 'serious', that 'apparatus' should not be separated off from the rest of the world into black boxes, as if it were not made of atoms and not ruled by quantum mechanics.

Quantum-based gravity sensors promise a sensitive and robust way to locate buried objects, and they've recently taken their first steps out of the laboratory, as Katherine Skipper explains.

FERROMAGNETISM, that most mysterious of the common properties of solids, has long known its place in the periodic table: down among the transition metals. These elements, which include iron and cobalt, have a net magnetic moment in the solid state because their atoms contain unpaired electrons. One of the last places you would expect to find ferro-magnetism is in carbon, because its electrons love to pair up to form covalent bonds. These bonds are the antithesis of magnetic order, so how can we explain the increasing number of reports of magnetism in carbon?

Donald Trump's second term as US president has begun with staff layoffs, slashed budgets, axed diversity programmes and cancelled conferences. Peter Gwynne examines the damage.

If you're a postdoc who wants to achieve a permanent faculty position, it's wise to publish a highly cited paper after your PhD, according to a study by an international team of researchers.

A new exhibition dedicated to Ukrainian scientists has opened at Harvard Science Centre in Cambridge, Massachusetts, US.

The International Year of Quantum Science and Technology got under way at an event at UNESCO headquarters in Paris last month. Matin Durrani reports from Paris.

Researchers in China have proposed a novel gravitational-wave observatory to search for cracks in Einstein's general theory of relativity using four satellites that form a tetrahedral structure in space.