special issue

The Little Bookof String TheorySteven S. Gubser“This is an engaging and conciseintroduction to the main ideas in stringtheory. Gubser gives us a quick tour ofthe basic laws of physics as we understandthem today, and then demonstrates howstring theory seeks to go beyond them.He serves as an artful and attentiveguide, as the reader explores the mysteriesof quantum mechanics, black holes,strings, branes, supersymmetry, and extradimensions in the pages of this book.”—Juan Maldacena, Institute forAdvanced StudyScience EssentialsCloth $19.95 £13.95 978-0-691-14289-03 At the cutting edgephysicsworld.comIPG Photonics40Physics and Technologyfor Future PresidentsAn Introduction to the EssentialPhysics Every World Leader Needsto KnowRichard A. Muller“Muller has distilled the most importantscientific principles that define ourchoices, and has presented them clearlyand objectively. To make wise decisions,not only future presidents, but futurebusiness and community leaders, andthoughtful citizens generally, need theinformation in this book.”—Frank Wilczek, Nobel Prize–winningphysicistCloth $49.50 £34.95 978-0-691-13504-5High Energy Radiationfrom Black HolesGamma Rays, Cosmic Rays,and NeutrinosCharles D. Dermer& Govind Menon“Filling an important gap in a topicaland fast-evolving area, this interestingbook will be a valuable addition to theastrophysics literature. The scientificcontent is of a high quality, and includesa notable level of rigor in the derivations.”—Peter Mészáros, PennsylvaniaState UniversityPrinceton Series in AstrophysicsDavid N. Spergel, Series EditorPaper $75.00 £52.00 978-0-691-14408-5Cloth $120.00 £82.50 978-0-691-13795-7(0800) 243407 UK800.777.4726 USpress.princeton.eduSparks fly as an ytterbium-doped fibre laser cuts a thick sheet of metal.deliver the beam as well as generate it – an approachthat makes the systems rugged and reliable, which iscrucial for industrial applications.The high efficiency and ease of heat dissipation allowfibre lasers to be small, and coupling fibres togetheravoids the need for complex beam-delivery optical systems,making them simple and convenient for researchapplications as well as industry. Erbium-doped fibrelasers can generate pulses lasting just a few femtoseconds(10 –15 s), as well as frequency combs, which gen -erate uniformly spaced lines across the visible andnear-infrared spectrum. There have even been propo -sals to use them on spacecraft for precision-measurementapplications. Fibre lasers have also demonstratedsome impressive research feats. Last year, for example,Al fred Leitenstorfer at the Univer sity of Konstanz inGer many used a fibre laser to generate the first singlecyclepulses – pulses that are literally so short that theycontain just one oscillation of light.Boom, bust, boomTechnology industries are notorious for their boom/bust cycles. The railroads went through them in the19th century, as did lasers in the late 1960s and early1970s. The telecoms bubble that peaked in 2000 wasunusual only in how badly it overinflated values, andhow hard it crashed. Survivors woke up the morningafter with a dreadful hangover, and swore they wouldnever binge again. But I suspect that if a new round offinanciers arrived with bucketfuls of money, the survivorswould go for it again, vowing that this time theywould take the money and run before it was too late.One thing is for sure, however: the global fibre-opticnetwork that under pins the 21st-century informationbasedeconomy has revolutionized the world – and willcontinue to do so for many years to come.Physics World May 2010