Table of contents

One clear result from the reader survey distributed with the July issue of Physic World was the large number of you who want more articles on the history and philosophy of physics. This came as a big surprise to us. We thought that we had responded to a similar message in our 1996 survey by publishing major articles on JJ Thomson, Cecil Powell, Paul Dirac, Patrick Blackett, Ernest Rutherford, John Bell and Marie Curie; Forum articles about philosophical topics such as the "science wars"; and a large number of books reviews in these areas. But it appears that this was not enough, so in this issue you will find articles about the late II Rabi, who received the Nobel prize for his work on magnetic resonance and nuclear physics (p27), and Frederick Guthrie, the outspoken chemist-turned-physicist who founded the Physical Society of London, which later became the Institute of Physics (p33).

In December Physics World will take a break from its normal format to celebrate the millennium.

Tornadoes, waterspouts and other atmospheric vortices are instanriy recognizable, but a detailed microscopic understanding of these phenomena continues to elude scientists. The same is true of vortices in super-fluids such as helium-4. Superfluids can flow without friction at low temperatures because the helium-4 atoms, which are bosons, all accumulate in the same quantum state, forming a Bose-Einstein condensate. Yet the strong interactions between the helium-4 atoms have hindered in-depth studies of the microscopic nature of superfluidity. Now Eric Cornell, Carl Wieman and co-workers at the JILA laboratory in Boulder, Colorado, have created a vortex in a dilute gas of rubidium-87, another Bose-Einstein condensate (M Matthews et at. 1999 Plys. Rev. Lett. 83 2498).

The interference pattern formed when a beam of electrons passes through a double slit is clear evidence that electrons can behave as both waves and particles. This wave-particle duality lies at the heart of quantum mechanics, but physicists remain intrigued by the boundary between the quantum and classical worlds. Neutrons, atoms and small molecules have all shown quantum-interference effects. Now Markus Arndt and co-workers at the University of Vienna have observed the wave-like behaviour of carbon-60 molecules. The "bucky-ball" molecules are at least an order of magnitude more massive than any other object where wave properties have been observed (Nature 1999 401 680).

Polarized light is used widely throughout physics. It can be employed to measure the magnetic and electric properties of materials, and to encode secret messages in quantum cryptography. But physicists are not alone in exploiting polarization. Bees and ants, for instance, use the pattern of polarized daylight as a compass. And now zoologist Marie Dacke at Lund University in Sweden and co-workers from Australia, the UK and the US have found that the eyes of Drossodes cupreus, a member of the spider family, contain polarizing optics unlike those of other insects (Nature 1999 401 470).

The last Nobel prize of the 20th century has been awarded to the two theorists who showed how to eliminate the infinities that plagued the unified electroweak interaction, and thereby laid the foundations of the highly successful Standard Model of particle physics. Gerard 't Hooft was working as Martinus Veltman's PhD student at the University of Utrecht in the Netherlands when he showed how to "renormalize" the electroweak theory. The pair then went on to work out the details of how to perform the calculations. 't Hooft and Veitman share the prize, which is worth SwKr 7.9 million (about £590 000).

Ahmed Zewail receives the 1999 Nobel Prize for Chemistry for the development of laser-based techniques that allow the motion of atoms inside molecules to be followed during chemical reactions. In these techniques, one laser pulse is used to initiate a reaction and a second pulse is used to probe it. By varying the time between the pulses, and measuring the absorption of the second pulse, it is possible to follow the reactions on femtosecond (10¹⁵ seconds) timescales.

Last month controversy gripped the world of motor racing when the winner of the Malaysian grand prix, Eddie Irvine, was disqualified after it was discovered that a side panel on his car was a few millimetres too narrow. Although Irvine was later reinstated, his disqualification goes to show how the tiniest engineering detail could make the difference between winning and losing in the multi-million pound sport of Formula One. This is why the construction team Benetton has got together with scientists and engineers from the nuclear industry to try and improve the performance of their cars.

Information and communication technologies are the pillars of the knowledge-based economy, and how countries adopt and master these technologies is the key to their future economic performance, according to a report published by the Organisation for Economic Co-operation and Development (OECD) last month. The Science, Technology and Industry Scoreboard reveals that knowledge-based companies – which include high-tech manufacturing firms and those in the service sector – now produce more than half of the average gross domestic product (GDP) of OECD countries, compared with just45% in 1985.

Technology has always been crucial to progress in science. When Galileo built his telescope in the 17th century he was able to view the heavens with unprecedented detail and discover that four moons orbited Jupiter, thereby dramatically refuting the idea that all astronomical bodies circle the Earth. Recognizing that nowadays science is even more dependent on technology, the Particle Physics and Astronomy Research Council (PPARC) is heading an initiative to identify tomorrow's technological needs across the science base. This long-term technology review is being carried Out by all seven research councils in the UK and will feed into the government's Foresight programme. It aims to encourage collaboration between disciplines that have common technological needs, and to identify technologies already developed in one discipline that could be used by another. It will also try and identify the technologies that could be made by industry and pinpoint potential commercial spin-offs.

Dyslexia is the most common learning disability estimated to affect between 5 and 15% of children. People with dyslexia have difficulty reading and spelling, but it is not related to intelligence. Indeed, dyslexics are often highly talented, and include among their numbers Einstein and Edison.

Nuclear physicists will have to wait another year before starting experiments on France's new radioactive beam facility SPIRAL. The Directorate for the Safety of Nuclear Installations (DSIN), which has been tightening its regulations in recent years, has issued a last minute ruling that the facility must undergo a public enquiry before it is authorized to accelerate radioactive beams. The facility will not now open until September 2000.

The US Senate's rejection of the Comprehensive Test Ban Treaty (CTBT) last month represented more of a political statement than a technological decision. Right-wing Republican senators made no secret of their distaste for any initiative backed by the Democratic President Bill Clinton. Many of those senators – notably North Carolina's Jesse Helms, who holds the powerful position of chairman of the Senate foreign relations committee – also used the vote to confirm their long-held views that America should pull back from its international obligations.

Physics-based companies may get a boost this month when the London Stock Exchange creates a new stock market called techMARK to track the UK's technology sector. The exchange has often been criticized for being too rigid since it requires companies that want to join to provide three years' worth of trading records. techMARK will not require such records, and start-up companies, particularly university "spin-off" companies, should therefore find it easier to float.

On a Saturday morning at the end of September three teams of physics and engineering students gathered at Southview Farm in Lincolnshire for the 1999 UK National Rocket Championship. As they prepared to launch their creations on their maiden voyages, the teams displayed varying degrees of anxiety.

When the great and the good met at the World Conference on Science in Budapest in June, one question was on many people's lips. How much has science changed since the previous World Conference held in Vienna 20 years before? One major development has been, of course, the collapse of science in eastern Europe and the former Soviet Union following the fall of communism. Less spectacular, but equally significant, has been the rising influence of the Third World Academy of Sciences, which was set up in 1983 in Trieste in Italy.

I was interested to read your editorial (September p3), which compared various aspects of physics in Europe and the US, in particular recent American successes in winning Nobel prizes. The article noted that the US has dominated the physics prize over the last two decades and that a significant fraction of 'American" winners were actually born elsewhere.

I read your news story about Germany's plans to donate the BESSY-I synchrotron facility to the Middle East (July p11) with great interest. It was heartening to note that the proposed synchrotron will be the seed for an international research centre built around the facility. Such a centre has been long overdue in the Middle East and will be the first of its kind in the region.

Lee Smolin is, of course, absolutely correct in pointing Out that Noether's theorem represents a deep insight into the fundamental behaviour of the physical world (October pp 13–14). However, I am intrigued to know just how he would go about teaching the concept of momentum to an average class of high-school students without invoking either mass or velocity, and I would also be interested to know whether he has actually done this with real students.

I would guess that many physicists, like me, feel that something is amiss when a university physics department is closed down – as has happened several times in the UK in recent years. What causes concern is that the rationale appears to be based purely on financial values, and not at all on those traditional academic values that distinguish a university from other educational establishments.

I recently spent an hour in my village pub in the annual ritual of transcribing all of my addresses and phone numbers from last year's Institute of Physics diary to this year's. This is always a rather time-consuming job, and, as I was doing a colleague of mine-a civil engineer-came in and remarked that it seemed an unnecessarily wasteful task. He showed me his diary, in which the address page comes as a separate section that can be tucked a plastic flap on the front or back inside cover. The user then has the choice of writing into the new section or transferring the section from last year's diary.

There is an old joke about a farmer who has a hen that will not lay eggs. After consulting unsuccessfully with a biologist, and then a chemist, he finally turns to a theoretical physicist. Several days later, the physicist announces that he has solved the problem: "First we assume a spherical chicken..." This story is a reminder that the art of approximation is crucial to most successful applications of theory to real problems; however, the proper level of simplification is not always obvious at the outset.

The Internet has created a boom in long-distance optical communications. Web surfers click away and download ever-larger files, oblivious to their distance from a Web host. As a result the demand for capacity in undersea optical-fibre communications is escalating. A simple way to increase the capacity is to send many separate optical wavelengths through the same fibre, a technique known as wavelength division multiplexing. However, there is a limit to the optical power that can be used to send information along a fibre, and this – rather than the bandwidth of the fibre, which is prodigious – limits the capacity of optical fibres to carry information.

The question of whether neutrinos have mass or not has fascinated physicists for many years because it has important consequences for the structure and evolution of the universe. In the big-bang model of the universe, enormous numbers of neutrinos were created in the early stages of the cosmological evolution and they survived in the form of a primordial "hot gas". Since neutrinos only interact very wealdy with other particles and do not emit radiation, they are believed to form a considerable component of today's universe. Indeed the average density of these so-called relic neutrinos is predicted to be of the order of hundreds per cubic centimetre. If neutrinos have a finite mass, albeit a very small one, they could play an essential role in accounting for the "missing mass" in the universe. Astronomers have found that over 90% of the material in the universe does not emit radiation and therefore cannot be seen, although its existence has been inferred from the gravitational effects it exerts on other luminous objects.

It has long been recognized that the basic units in science – such as the second and the kilogram – should be defined in terms of fundamental physical phenomena. Indeed in 1870 James Clerk Maxwell recognized that the units of length, time and mass would only remain unchanged and reproducible if they were defined by the wavelength, period of vibration and absolute mass of molecules rather than by the physical properties of the Earth. However, it took over a century for the metre and the second to be defined in terms of the quantum properties of atoms. And it was only in 1990 that reproducible standards of voltage and resistance were linked to quantum phenomena.

Astrophysicists have long been fascinated by black holes, although convincing evidence for their existence has only emerged in recent years. In galaxy NGC4258, for instance, an intensely bright source of microwaves appears to orbit round a massive "unseen" compact object. And in our own galaxy, infrared observations point to a group of rapidly moving stars that seem to be in orbit about a black hole with a mass at least a million times that of the Sun. Now astronomers have made what may be the first direct observation of material from a supernova event that created the black hole in an X-ray binary-star system (G Israelian et al. 1999 Nature 401 142).

When a vertical jet of water from a tap or faucet hits the bottom of a sink, the water spreads out in a thin sheet. At a certain distance from the point where the water hits the sink, however, there is a sharp step. Beyond this step, the flow is thick and slow. This is a classical example of a shock in shallow water. Such shocks were first studied by the French physicist Felix Savart as long ago as 1833, and are still an active area of research.

A few months before Isidor Isaac Rabi died in early 1988, his doctors watched as he was gently moved into the bore of a magnetic-resonance-imaging machine. Once inside the machine, Rabi saw a distorted image of his face in the cylindrical surface surrounding him. "It was eerie," Rabi said. "I saw myself in that machine. I never thought my work would come to this." An eerie moment? Certainly – since Rabi's physical research led directly to magnetic resonance imaging, a technique that is widely used in hospitals today.

This year the Institute of Physics has been celebrating its 125th anniversary. As the year draws to a close, it is appropriate to take a closer look at its founder, Frederick Guthrie, to appreciate his reasons for founding a learned society for physicists.

The nature of time has always been perplexing, and developments in modern physics have only increased that perplexity. In the classical Newtonian view, which assumed a background of absolute space, time was like a flowing river that passed at the same rate for everyone. That view was demolished by special relativity, which showed that space and time measurements depend on motion: there is no universal "now", and time flows at different rates for different observers.

In mid-December 1900 Max Planck presented a series of papers to the Prussian Academy of Sciences in Berlin that were, eventually, to revolutionize not only physics as a discipline, but our entire conceptions of the constitution of matter and energy. It would be fair to say that the century that followed was the century of physics par excellence, just as – if one were to believe recent developments – the coming century will be that of molecular biology and the study of the mind.

This delightfully written little book is full of typically Dysonian intellectual sparkle. It is based on three public lectures given at the New York Public Library in 1997, in which the physicist Freeman Dyson looked forward to the coming century, sharing with us his unique breadth of view and receptiveness to technical innovation.

When I was asked to review what is an "updated" version of George Gamow's Mr Tompkins in Paperback, I was sceptical about what the book was going to be like. For updating a classic is no easy job. Imagine updating the Sherlock Holmes stories, with the hansom-cabs replaced by minicabs, country houses by high-rise apartments, and with the master sleuth surfing the Internet to trace the murky past of some suspect. It just wouldn't be classic any more. However, as I read on, I warmed to Russell Stannard's attempts to tackle the difficult job ahead of him. As he confesses in the foreword, he is aware that his approach might not please everyone.

Jim Al-Khalili has produced, with earnest intentions, a concise, well written book about some of the exotic features associated with general relativity, in particular two of the topics in the title of the book: black holes and time machines. I wish I could more enthusiastically recommend it, but I cannot.

Charles Townes has written a biography – but it is not clear if it is his own or that of the laser. The laser is now such a feature of our everyday life that the remarkable story of its birth needs to be told, and Townes does so in a clear and personal way – because he was there when it happened.

A new non-contact measurement probe from Optimet uses novel conoscopic holography techniques to create extremely precise three-dimensional digital images of virtually any surface, including machined metals and other relatively shiny objects. The Conoprobe 1000 can measure up to 700 points per second while the probe is in motion, and by changing the objective lens the working range covers sub-microns to metres. In most cases the precision and repeatability are better than 1/8000th of the working range. The device can measure at angles very close to grazing incidence, and its design allows the measurement of narrow and deep holes of less than 1 mm diameter with depth to diameter ratios of 25:1.

Physicists have been rightly labelled as love machines – after all, we have been credited with causing over 90% of all divorces. We drink too much, break too many laws, and provide far too much material for daytime TV talk shows. Naturally, this means that the youth of our world absolutely worships us. Young children have posters on their walls of the most talented and attractive physicists, usually pictured wearing nothing more than a pair of protective goggles. Paris fashion shows are awash with models trying to mimic the waif-scientist look.