Table of contents

One of the most unusual predictions of quantum mechanics is that, under certain conditions, individual particles can have no real properties of their own. Surprising as it seems, this lack of so-called local realism has been confirmed many times in experiments with pairs of photons. It has now been confirmed for the first time in experiments with three-photon states (J-W Pan et al. 2000 Nature 403 5 15).

The recent demonstrations of laser-like amplification of atomic beams by Bose-Einstein condensates, less than five years after the first condensates were created, shows just how rapid progress has been in this field (see page 24). Now physicists are attempting a repeat performance with molecules (R Wynar et al. 2000 Science287 1016).

Particle physics grabbed the headlines last month when CERN told the international media that it had created a new state of matter. Researchers working at the European centre for particle physics announced that they had "compelling evidence" for a soup of free quarks and gluons, thereby reproducing the conditions that existed when the universe was just 10 millionths of a second old. However, they stopped short of claiming that they had discovered the much sought after "quark–gluon plasma", something that would have profound implications not only for cosmology, but also the Standard Model of particle physics.

Two observational techniques recently pioneered in the US have strengthened space scientists' ability to carry out their vocation. One involves the use of high-performance jet aircraft as platforms for astronomy. The other uses minuscule satellites to undertake a variety of near-Earth observations.

An Italian physicist has come up with a way of distinguishing between pop and classical music using theoretical techniques from seismology. Paolo Diodati of Perugia University investigated the difference in the intensity patterns of classical and what he calls "light" music, such as jazz, pop and rock music. He found that the light music could be described by a Gaussian or noise distribution, whereas classical pieces are characterized by more complex statistics.

In the 1960s the drug thalidomide led to enormous tragedy in the UK. The reason was that the drug was a "chiral" molecule – a molecule that is present in left-and right-handed mirror image forms. One form acted as a safe painkiller; while the other caused severe abnormalities in foetuses.

"Science without conscience is but ruin of the soul," wrote the French scholar François Rabelais in the early 16th century. France has a great tradition of philosophy and now Claude Allégre, the French minister for education and research, believes it is time for science to profit from it. Last month he announced a series of measures that will make the study of philosophy compulsory for all science students. Over the next three years, philosophy and the history of science will be integrated into all science degrees, masters-level courses and engineering diplomas from the Grandes Ecoles.

As the American economy completed a record 109th consecutive month of growth last month, the Clinton administration presented its budget proposals for the financial year 2001, which starts on 1 October this year. And as the economy blossoms, the administration wants to share some of the country's burgeoning budget surplus with the scientific community. It is therefore seeking to increase the funding for civilian R&D by 6% – the eighth increase in as many years. Basic research, meanwhile, stands to rise by 7% under the proposals. However, the budget will have to be ratified by the Republican-dominated Congress, which will put the proposals under particular scrutiny before the presidential elections in the autumn.

Imagine a full-colour flat-screen television that can be hung from your wall–and costs less than £1000. That prospect could be a reality within four years, according to Printable Field Emitters (PFE), a high-tech firm based at the Rutherford Appleton Laboratory in Oxfordshire. The company, which was founded in 1995, has developed a new type of "field-emitting display" that, it believes, could lead to the holy grail of the displays industry – flat-screen TVs between 20 and 40 inches in size, at prices that consumers can afford. The market for such products should grow to $31bn by 2002.

BT is to license its photonics technology to Corning, the US optical-systems group, in an attempt to get its research ideas onto the market more quickly. The £39m deal includes the transfer of BT's world-leading photonics technology research centre at Martlesham Heath in the UK to the US firm. All 43 staff at the centre will join Corning, which will receive licences to 20 of BT's patent "families" in electroabsorbtion modulators, semiconductor optical amplifiers, grating-stabilized lasers and fibre lasers. BT will also receive royalties from any products that are developed from its technology.

You say you want a revolution? Then you need look no further than the world of scientific journal publishing. Driven by the meteoric increase in the Internet's power to deliver information, this revolution is already fundamentally changing the way scientists communicate with each other. And the revolutionaries are now pounding on the castle door and calling for the head of the king of modern scientific correspondence: the printed journal.

All scientists like to have their papers cited by other authors – it is a sign that their work has at least been read by their colleagues. Indeed, the study of citations has turned into a mini industry, with the "impact" – the number of citations an author receives divided by the number of papers he or she has published – being used as a measure of research quality. Statisticians also use citations to compare the research output of different nations. They calculate what is known as the "relative citation impact", which is the impact of papers by authors from a particular country in a particular field, divided by the average impact for all papers in that field. The relative citation impact is usually used to compare how different countries fare in a particular subject, such as physics.

What do Stonehenge, the human species and the plays listed in any issue of the New Yorker have in common? According to Richard Gott, an astrophysicist at Princeton University in the US, the length of time that any of them is likely to survive can be predicted by a formula based on the Copernican principle – the assumption that we live in an unexceptional time and place. Gott's work, first published in Nature in 1993, has received widespread coverage, including an article entitled "How to predict everything" in the New Yorker itself last year.

Shuji Nakamura, the Japanese physicist who invented the blue semiconductor laser, has moved from Nichia Chemical Industries in Japan to the University of California at Santa Barbara. Nakamura, who is 45, said that he had "decided that an academic context would now be better for his work". He added that his move to the US was prompted by the poor salaries and lack of freedom in Japanese universities.

News in brief articles for March 2000

The Millennium Dome in London – a £758m high-tech visitor attraction that was built largely with government money – is a national laughing stock in the UK. But at least the Dome opened on time. If only the same could be said for DIAMOND, a third-generation synchrotron radiation source that will be used by scientists from the UK and France. Seven years after the case for a new medium-energy synchrotron source was first made, the inability of the government's Office of Science and Technology to decide where to build DIAMOND – which will cost about £550m to build and operate over a 20 year period – has moved from comedy to farce. A decision is expected as Physics World goes to press, just as it has been every month the past year.

Our greatest endeavour in basic science over the past century has, undoubtedly, been the study of the electromagnetic, strong and weak forces. Although the general theory of relativity was formulated more than 80 years ago, gravitational forces are only now entering the arena of basic scientific research. This is happening because the greatest synthesis of all time, which describes the basic interactions of all the known elementary particles, has finally been achieved in the form of the Standard Model of particle physics. This synthesis is the result of the work of physicists the world over, who have dedicated themselves to the study of what happens when the stable building-blocks of matter (protons, electrons and nuclei) are made to interact at higher and higher energies.

Alan Calverd's lateral thoughts article (February p60) raises the issue of how to quantify various kinds of risk. A further difficulty, which may lie at the heart of the problem of how people perceive risk, is how to compare risks that individuals choose to accept with those imposed by others, whether by society or the environment. Another complication is that some (albeit rare) events may cause hundreds or thousands of fatalities, whereas others (albeit common) may cause a similar number of deaths in a given period, but in ones or twos.

Congratulations on your excellent millennium special issue. As one looks forward to the 21st century, it is good to stand aside from one's current professional concerns and view physics from the wider and longer perspective that you provided – determining what has been achieved and how and what we can see ahead.

Readers may like to know that the John Muir Trust – named after the 19th-century Scottish naturalist – recently purchased the eastern end of the Scottish mountain Schiehallion, including the summit, and has now launched an appeal to raise the rest of the £300 000 needed for managing the mountain and conserving its environment. Schiehallion was the site of Nevil Maskeleyne's famous 1774 experiment, often described as "weighing the Earth", in which he measured the universal gravitational constant, G, for the first time.

Andrew Pinsent's letter about the Church's influence on science over the years (February pl8) exhibits the narrow-minded attitude of Galileo's contemporaries. He also ignores the other cultures and societies that had made the same (or similar) advances learning centuries or millennia earlier. The Catholic/Christian church – like other monocultures – sought to repress individual thought and ideas that conflicted with its ad hoc beliefs. Congratulating the Church on overseeing the scientific advances that he lists is much like congratulating Chairman Mao or Stalin on the scientific, economic and industrial "advances" made in their societies.

We were interested in the discussion about whether "therapy magnets" can have therapeutic effects on humans. Although we do not want to enter the debate about whether the application of a modest static magnetic field (SMF) can lead to "pain relief", we would like to point out some scientific facts to help shed light on the discussion. Indeed, recent experiments show that the case against such magnets having any effect on humans is by no means closed, as Robert Park suggests in his letter (January p16).

Many of the leading figures in the world of string theory met at the California Institute of Technology in January to discuss recent progress in the field and to reflect on the state of the theory. The enthusiastic mood of the gathering was based on the fact that string theory provides an elegant framework for a unified theory of all the forces and particles in nature, and also gives a consistent quantum-mechanical description of general relativity. (Most of the transparencies from the conference are now available on the Web at wwwtheory.caltech.edu/conf2000/ program.html)

The first field effect transistor was invented by Julius Lilienfeld in 1925; he probably never got it to work. It took almost another 35 years before Dawon Kahng and John Atalla of Bell Laboratories in the US demonstrated the first metal-oxide semiconductor field effect transistor (MOSFET) – a remarkably simple electronic device based on silicon technology This transistor revolutionizcd the electronics industry because large numbers of MOSFETs could be fabricated and interconnected on the surface of a small silicon chip.

Electrons and holes, which carry the current in semiconductor devices, are quantum-mechanical objects characterized by a set of quantum numbers – the band index, the wave-vector (which is closely related to the electron or hole velocity) and spin. The spin, however, is one of the strangest properties of particles. In simple terms, we can think of the spin as an internal rotation of the electron, but it has no classical counterpart. The spin is connected to a quantized magnetic moment and hence acts as a microscopic magnet. Thus the electron spin can adopt one of two directions ("up" or "down") in a magnetic field. The spin plays no role in conventional electronics and the current in any semiconductor device is made up of a mixture of electrons with randomly oriented spins.

In 1929 Prince Louis de Broglie was awarded the Nobel prize for discovering the wave nature of massive particles. He showed that particles had an associated wavelength of λ = h/p, where h is the Planck constant and p is the particle's momentum. An inescapable consequence of the wave-like nature of matter is the field of matter-wave optics. This principle was first demonstrated with electrons, then later with neutrons and, most recently, with atoms and molecules. However, the early work with atoms was severely hindered by the difficulty of producing high-flux beams of monoenergetic atoms.

Just over five years ago, astronomers had no evidence for planets circling Sun-like stars outside our solar system. This situation changed in 1995 when Michel Mayor and Didier Queloz at the Geneva Observatory discovered a massive planet orbiting just 7 million kilometres from its star. Now, planets are routinely detected around other Sun-like stars. Indeed, 30 extrasolar planets have been discovered so far, compared with just nine planets in our solar system.

Over a dozen years have passed since high-temperature superconductors were discovered amid a rash of over-enthusiastic claims that these materials would immediately revolutionize the power, transport and communications industries. The public perception may be that after years of research and unprecedented industrial investment there still seems to be no theory of high-temperature superconductivity, and no practical applications either. However, the reality is very different. Many aspects of the physics and chemistry of cuprate super-conductors are now well understood, while the remaining problems are providing a rich source of new physics (see "The underdoped phase of cuprate superconductors" by Bertram Batlogg and Chandra Varma Physics World February 2000 pp33–37). More importantly, however, a wide range of major industrial application are set to appear within the next few years.

No one can have failed to notice the tremendous growth of mobile or cellular telecommunications in recent years. According to market reports, there are over 24 million mobile-phone users in the UK alone, and a staggering 4 million phones were sold in the three months leading up to Christmas. The story is similar in other European countries. In Finland, for instance, over 60% of the population own a mobile phone, while the number of mobile phones in Italy exceeds the number of fixed lines. Little wonder then that there is such stiff competition between telecommunication companies!

Since its discovery almost two decades ago, the quantum Hall effect has been investigated by an exceptionally broad community of physicists, ranging all the way from materials scientists to topologists. Although the integer and fractional quantum Hall effects were discovered in the early 1980s, they are still the focus of a large research effort worldwide, and many new phenomena have been discovered in recent years. These include objects as diverse as composite fermions, skyrmions and fractional charge carriers.

In 1897 Max Planck wrote the following about the question of whether women should be allowed to study at German universities: "If a woman has a special gift for the tasks of theoretical physics...I do not think it right, both personally and impersonally, to refuse her the chance and means of studying for reasons of principle." But then he added: "On the other hand, I must keep to the fact that such a case must always be regarded just as an exception. Generally, it cannot be emphasized enough that nature herself prescribes to a woman her function as mother and housewife."

So, as the blurb on the cover proclaims: What Science Is and How It Works is an outstanding book by a fine writer. Physical scientists, especially, will love it, for it largely adopts their perspective. Indeed, the last quarter of the book deviates into their favourite themes, such as dimensionality, chaos, symmetry, feedback and nonlinearity. Strangely, though, Derry does not ask the big questions about die "unreasonable efficacy" (as Eugene Wigner once put it) of madiematics in science, and backs away from algebra and algorithms into arithmetical talk about "models".

Mike Fortun and Herbert Bernstein's book is a masterpiece – a particularly intelligent, useftil and unusual book. It will constitute, I strongly believe, a solid mooring point to help us face the challenges and questions – scientific, philosophical and political – that the new century is forcing on us. The book is also refined and subtle enough to help us to avoid (and hopefully to forget) the crude, sterile and empty confrontation, known as the "science wars", that have raged over the last few years. This book must be read, reread and reflected on by everybody – for by arguing that science is a complex and messy business, the authors could have a major effect on how we think about science, about science as knowledge, and about science and politics.

A few years ago the owner of the snack-bar in the physics institute at the University of São Paulo started selling sandwiches. But these were no ordinary sandwiches – they unwittingly served as a teaching aid to help explain various concepts that were being taught to physics students. Unfortunately, my true story does not have a happy ending.