Physics World

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

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.

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)."

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.

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.

The interaction between science and religion has a long history Many medieval scientists held positions in the church, Einstein famously said that God did not "play dice" with the universe, while the conflict between Galileo and Pope Pius V was one of the key events in the history of science.

Gordon Moore, the co-founder of Intel who died earlier this year, is famous for forecasting a continuous rise in the density of transistors that we can pack onto semiconductor chips. James McKenzie looks at how "Moore's law" is still going strong after almost six decades, but warns that further progress is becoming harder and ever more expensive to sustain.

In the spring of 2002, the world's most productive young scientist was a 31-year-old physicist at Bell Labs in New Jersey in the US. With eight papers published in Nature and Science in 2001 alone, Jan Hendrik Schön was emerging with breathtaking speed as a star researcher in physics, materials science and nanotechnology. His research was based on an unrivalled ability to transform the properties of materials by the application of an electric field. He built high-performance transistors made not from silicon but from carbonbased materials. He coaxed materials into superconductors, which have an almost magical ability to conduct electricity without resistance. He described the world's first organic electrical laser, and the first ever light-emitting transistor. He even claimed to have built the world's smallest transistor by wiring up a single molecule. It was a dazzling nanotechnology triumph.

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.

Researchers at Cornell University have used highspeed cameras to understand how whirligig beetles can reach speeds of up to 1 m/s as they skirt across water.

Scientists in China and the US have investigated how fire raft ants avoid drowning in heavy rain by clumping together to form floating rafts.

How many pieces of fruit can you remove from a pyramid before the whole mound collapses? According to researchers in Chile it depends on the slope of the pyramid – about 10% in the average supermarket display.

A team from Seoul National University has investigated the physics of what happens as a liquid is poured into a cup or mug from different heights.

Quantum simulator visualizes large-scale entanglement in materials thanks to a 50-year-old quantum field theorem, as Martijn Boerkamp reports.