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Revealing the invisible

Physicists, more than most people, are accustomed to dealing with gases. Yet even physicists often treat gases as something to be taken for granted, a sort of Platonic ideal with interesting or useful properties but with little connection to the world outside the laboratory. Whether as natural resources or something to be delivered in cylinders, gases are just there.

But of course gases, at any rate those in cylinders, do not just happen. They are the products of a multi-million-pound global industry that links science, technology and business in a virtuous circle of discovery and development. The story of gases starts at the dawn of science and goes on to touch almost every area of modern life.

Industrial gases are those gases that are commercially important, especially the so-called “merchant gases” that are sold from one company to another and transported in pipelines, tankers, cylinders and insulated flasks. They crop up everywhere, from a steelworks that uses 2000 tonnes of oxygen per day to the semiconductor fabrication plant handling kilogramme quantities of high-purity silane and other exotics.

Truck and aircraft tyres are often filled with nitrogen to reduce the risk of fire. Liquid carbon dioxide dissolves biocides for controlling agricultural pests and bacteria in air-conditioning systems. Ice-cream moulds chilled to -80 °C with liquid nitrogen become “non-stick”. The poor thermal conductivity of krypton is useful in electric lamps and double glazing. Ethylene is used to control the ripening of bananas and other fruit.

Hydrogen, with its low viscosity and high thermal conductivity, is used to cool alternators in power plants. Oxygen improves the economics and environmental performance of many combustion processes. Ultra-pure gases and gas mixtures are essential for semiconductor manufacture, gas chromatographs and particle detectors, while liquid helium cools superconductors and radiation detectors.

Invisible they may mostly be, but gases are all around us. Just as interesting as the applications are the ways in which the gases are manufactured. Even to those of us who know something of cryogenics, compression, expansion and distillation, it is remarkable that we can buy liquid oxygen for around £20 a tonne. Helium is more expensive not only because it has a lower boiling point, but also because of its rarity. Although helium is common in natural gas, only in the US and Poland is the concentration high enough to make extracting the helium worthwhile.

Apart from cryogenic distillation, adsorption technology provides a useful source of smaller quantities of atmospheric gases for applications in which it is important to be able to generate gases near their points of use. Pressure-swing adsorption (PSA) plants are slowly growing in scale, to the point where small steelworks are now using PSA units producing some tens of tonnes of gas per day. Membrane separation systems, currently expensive and limited in scale, promise even greater convenience.

Industrial gases cover such a wide area that they need a big book to do them justice, and that is just what Neil Downie has produced. Industrial Gases is not physically large by textbook standards, but its scope is another matter. It contains four chapters: a brief introduction to gases and the gases industry; two substantial sections on gas technology and industrial applications of gases; and a short chapter on the future of the industry. All four chapters are well balanced, accurate and up-to-date.

After a quick overview of the history of gas manufacture and applications, the introductory chapter summarizes the physics and physical chemistry of gases giving examples of common gases. I found the last part of this chapter the most interesting, since it gives a very competent summary of the structure of the gases industry and its commercial drivers.

The section on gas technology covers manufacture, handling and storage, measurement and analysis, and safety and environmental issues. There is such a lot of ground to cover that the reader may worry about not finding sufficient detail. My own feeling is that, having included the correct amount of background information, the author has got it just right.

However, as someone who specializes in applications for industrial gases, I would have liked more detail in the chapter about how gases are used. But this is nit-picking; the book has to stop somewhere, and this section is well balanced and as detailed as it is possible to be in 200 pages covering such diverse topics as anaesthetics, fertilisers and carbonated drinks. The content is up-to-date and the illustrations are basic but clear, although the index could be better.

Industrial Gases is well written in a refreshingly personal style. Perhaps Downie’s background as a consultant helps here. After all, consultants need to sell themselves, and more than most other scientists and engineers they are likely to suffer if their communication skills are not up to scratch. Combined with the wide-ranging content, the result is as close as a technical textbook gets to bedtime reading.

After I started work in a company making industrial gases, it took me five or six years to gain a reasonable grasp of the industry: its products, technologies, business models and people. With the aid of this book, today’s new recruits can cover much of this ground in five or six days. Industrial Gases will be essential reading for people in the gases industry and an excellent read for anyone who is simply curious about where their laboratory nitrogen comes from.

Astronomers see extra-solar planetary debris

Planets are thought to form from the debris surrounding young stars. As material rotates around the star, gravitational attraction causes the debris to clump together into planets. Gradually the planets sweep up the debris and dust in their orbit, decreasing the amount of material in the star’s rotational axis. For example, if our solar system was observed from a distance at submillimetre wavelengths, the brightest dust emissions would occur at some distance to the Sun.

When the groups observed Fomalhaut – a young star – they found that the brightest dust emissions existed some distance away from the star. There was also a dust-free central cavity, approximately the size of Neptune’s orbit, between the star and the main emission bands. The amount of dust seen by the detector only totalled a few lunar masses, leading the researchers to believe that planetary formation has swept the material away.

Although both Vega and Beta Pictoris also have their brightest dust emissions some distance away from the main star, the astronomers found that both stars had a concentrated peak of dust emissions that appears as a ‘bright blob’ in the detector. One possible explanation is that the ‘blobs’ are dust-shrouded Jupiter-sized planets orbiting at vast distances from the star. If this is true, then our understanding of planetary formation dynamics would have to be rewritten to explain their formation.

New ways to search the web

Search engines such as Hotbot and AltaVista record a list of pages with keywords in them, but cannot interpret how relevant the information is on the page. For example the word ‘quantum’ returns 778, 930 references through AltaVista, but doesn’t state how many are physics related.

Kleinberg’s program analyzes the links between Web sites by splitting the search algorithm into two sections: ‘authorities’ that have useful information about a topic; and ‘hubs’ that contain directory links to the topic. The best authorities, Kleinberg says, will be those that point to the best hubs, and the best hubs will be the ones that point to the best authorities. The relationship is recalculated several times to improve accuracy and to prevent circular patterns forming.

A search on HITS starts by collecting the first 200 pages from a keyword query on AltaVista. The program then looks at all the additional pages linked to this ‘root’ set and how these pages are connected together. Pages which are pointed to by many Web sites are assigned a high authority ‘score’, while pages that link to many external sites are given an additional hub ‘score’. These last two calculations are repeated several times, with each cycle awarding more authority points to sites that link to high scoring hub sites, and more hub points to high scoring authority sites. Ten repetitions, Kleinberg says, are enough to return surprisingly focused lists of authorities and hubs.

The program is especially useful with vague terms such as ‘quantum’ as it will then sort the data into different communities, such as physics, software companies, equipment and so on, or with sites that have extreme views, such as ‘cold fusion’. This is because each group will tend to link to similar groups, and not their opposing members.

Students sign up for physics with finance

Financial institutions already employ physicists because they are uniquely familiar with the mathematical and conceptual thinking needed to understand financial risk in, for example, currencies and property.

Previously these physicists have had to learn about finance on the job. Andrew Hirsch, head of the physics department at Purdue, hopes that the new course will change this. “I believe that our course is unique, ” he says. “We’ve looked at other computational finance and financial engineering programmes, and none has an active engagement with a physics department.”

Purdue has already been contacted by several Wall Street firms about the availability of students from the course.

German elections delay ESA shake-up

The meeting was due to be held in Belgium at the end of June. However, Yvan Ylieff, Belgium’s minister for scientific policy and organizer of the meeting, has announced that disagreements over the future direction of the agency, and the forthcoming national elections in Germany, have caused the meeting to be abandoned. The election is leading to uncertainties about how much Germany will contribute to ESA in the future.

Antonio Rodotà, director-general of ESA, has been trying to make the agency’s work more relevant to industry, especially in areas such as telecommunications, multimedia and Earth observation, in an effort to attract funding from industrial companies. Rodotà is also keen to sub-contract the management of entire projects to the private sector in an effort to reduce costs. This new approach was to have been tried on EuroMoon 2000, a mission to the Moon, but ESA’s board of directors cancelled the project at a heated meeting at the end of March.

Funding for space science has also suffered. Two missions – an infrared telescope called FIRST and the Planck mission to measure the cosmic microwave background – have been merged to reduce costs, and Mars Pathfinder is threatened with cancellation.

Only eight of ESA’s fourteen member states have publicly supported Rodotà’s new policies, but officials hope that a consensus on the agency’s long-term strategy will be finalized before the end of the year.

Industry funds ‘son’ of Internet

Three companies are investing in the project. Qwest Communications, one of the world’s fastest growing telecommunications companies, is donating 16000 miles of fibre optic cabling to the project, while Cisco Systems and Nortel have offered equipment ‘in kind’. All three companies see Internet-2 as an ideal test bed for the next generation of high-speed switching equipment. Prototypes of their latest designs will be tried out on the new network before going into general use.

The project is being led by the University Corporation for Advanced Internet Development (UCAID), a consortium of universities that is concerned about the poor performance of the existing Internet. UCAID had originally planned to operate Internet-2 at 622 million bits per second (bps), but the new investment means that it will now be capable of sending four times as much information.

“I applaud the extraordinary commitments of these companies, ” said Gore. “In the coming years, this investment may enable the best medical specialists to give advice to patients in rural hospitals, scientists to use remote supercomputers to predict tornadoes, and adults to get new skills through distance learning.”

New features on PhysicsWeb

Registration is free for members of the Institute of Physics and individual Physics World subscribers. A standalone subscription to PhysicsWeb costs £25. Free trial registrations are also available.

The main change that users will notice is that they will have to give a username and password to access some parts of the site. The alerting service, which is free to everyone, will email summaries of new material to users as soon as it is uploaded on PhysicsWeb.

See subscriber options for more details.

PhDs improve US job prospects

The report also found that the PhD unemployment rate varies with the age at which people received their PhD. The rate varies from 0.6 per cent for those receiving PhDs before the age of 26, to 5.8 per cent for those above 40. The report also finds that unemployment rates are lower for male PhDs who are married compared with those who are single, with the opposite happening for female PhDs. The figures also reveal that teaching is the most secure profession, with only 0.4 per cent of physics teachers with PhDs unemployed.

US Energy Secretary resigns

During his term in office Peña has promoted management reforms across the department and increased transparency at the national labs. Peña’s involvement in promoting awareness of the greenhouse effect and climate change at the White House was considered crucial in obtaining US support for the Kyoto agreement on carbon dioxide emissions.

In a statement Peña pointed to the DOE’s record in developing world class research, and spoke of how new facilities such as the National Ignition Facility and the National Spallation Neutron Source will maintain US prominence in physics.

President Clinton will have to appoint a replacement as soon as possible. Over the next few months, the DOE has to introduce increased competition to the US electricity market, ship nuclear weapon grade material from Russia to the US, and agree a procedure with the US nuclear electricity companies for the disposal of radioactive waste from nuclear power plants. Moler’s experience with these programmes makes her appointment to the post very likely.

Europe to promote venture capital

The commission hopes that by making capital accessible to companies, Europe can help reduce the high level of unemployment affecting the continent. Unlike the US, where a large number of venture capital firms promote and support a number of small high-technology companies, obtaining finance for similar ventures in Europe is exceedingly difficult. Few companies provide venture capital to start-up firms and fewer still understand the risks or rewards associated with high-technology investment.

The six points of the initiative are:

Promote the integration of fragmented venture-capital markets in Europe;
Eliminate institutional and regulatory barriers to the development of venture capital markets;
Ameliorate tax demands concerning venture capital;
Promote the development of small-medium enterprises in the high-tech sector;
Increase the number of entrepreneurs and qualified experts; and
Attack cultural barriers to the creation of enterprise and risk-taking.

The council of Ministers of Finance will discuss the commission’s proposals on the 21 April.

The initiative comes at a time when US venture capital funds are looking to Europe for investment opportunities. US venture capitalists also tend to invest more in high-tech companies that their European counterparts. According to Price Waterhouse, total venture capital investments in the US reached $12.8 billion last year, 30 per cent more than 1996, with most of the increase going to high-technology firms. In the UK, $5.2 billion was invested by venture capital funds last year, but only $132 million was invested in early-stage technology companies.

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