physicsworld.comFeedbackLetters to the Editor can be sent to Physics World,Dirac House, Temple Back, Bristol BS1 6BE, UK,or to pwld@iop.org. Please include your address anda telephone number. Letters should be no more than500 words and may be edited. Comments on articlesfrom physicsworld.com can be posted on the website;an edited selection appears hereEensey, weensey unitsYou reported last month (April p3) on theefforts of Austin Sendek, a physics studentfrom the University of California, Davis,to establish the “hella” as an officialInternational System of Units (SI) prefixfor 10 27 . You also asked for suggestions onunit prefixes that go down to 10 –27 – butsurely this is not difficult. I have longdeclared the “tini” (pronounced with an“ee” sound) to denote this quantity. Thisdesignation has the additional value ofsuggesting the subsequent two prefixes aswell: the “insi” (pronounced “eensey”) for10 –30 , to be followed closely by the “winsi”(pronounced “weensey”).I have tried to think of prefixes thatwould come in on the high end beyond“hella” but unfortunately I could think ofnothing that could not be interpreted as arude word. Maybe I should not havelimited myself to the English language.B Todd HuffmanUniversity of Oxford, UKt.huffman1@ox.ac.ukWe already have the prefix “zepto” for10 –21 , but this is clearly a mistake for“zeppo”. Could we not have groucho,chico and harpo as prefixes for 10 –27 , 10 –30and 10 –33 ?Keith DoyleWalton on Thames, Surrey, UKkeith.doyle@lloyd-doyle.comThere is no need for a new “hella” prefix, asan extended set of SI prefixes has alreadybeen suggested by Victor Mayes. Writing in1994 in the Quarterly Journal of the RoyalAstronomical Society (35 569) Mayes’suggestion for 10 27 was “nava”, from theSanskrit for nine (10 27 = 1000 9 ). He alsoComments from physicsworld.comUsually, the “most commented” articles onphysicsworld.com are those that concerncontroversial science policies, rather thanscience itself. Now and then, though, a scientificstory – in this case a proposed method forstoring wind energy in giant undersea bags –captures readers’ imaginations (“Spin-out putsnew spin on wind energy” 30 March; see alsop8). The idea would see pistons inside the bladesof giant wind turbines used to pump compressedair into storage balloons; on calm days, thestored air could be released to drive a setof turbines, thus ensuring a continuous supplyof electricity. According to inventorSeamus Garvey, a similar scheme could helpstore surplus energy from nuclear reactors. Aninteresting notion, certainly – but is there acatch somewhere?The proposal to use a bag system for storing“surplus energy from nuclear reactors” soundsfunny. It’s designed to store energy from unreliablesources, so I’d stick to that – it’s wind generatorsthat are causing mayhem on our energy grid, notnuclear plants.kasuha, Czech RepublicI agree that you should confine this system to wind,but I disagree that wind is causing havoc on thegrid. We also need to look at the environmentalimpacts, which will be significant if we startinstalling thousands of floating airbags at thebottom of the ocean. But then again, nothing isworse than coal and gas.gunslingor, USYou probably haven’t had enough blackoutscaused by wind turbines overloading the grid yet.Environmental or not (and I think these bags are farfrom environmentally friendly – they are going todamage quite large areas of sea bed), windturbines are causing many problems anddesperately need reliable means of energy storage.kasuhasuggested “sansa” for 10 30 (san-shi beingChinese for “thirty”); “besa” for 10 33 (besarmeans “great” in Malay-Indonesian) andso on up to “ultra” (Latin for “beyond,extreme”) for 10 48 . In a similar vein, Mayes’system assigned “tiso” (Arabic tis’a or“nine”) to 10 –27 ; “vindo” (from Hindivindu, “a speck”) to 10 –30 and “weto”(Maori wheto, “small”) to 10 –33 .High winds knocking down power lines is what’scausing mayhem on our grid, not wind generatorsor nuclear plants. Bring on the undersea bags!dratman, USThe bag might be a problem. I propose a simplersolution to store the air underwater: an open-endedcan or concrete caisson, sealed at the top andopen at the bottom. No moving parts.AlanMWouldn’t it be a lot easier to pump water up a hill?John Duffield, UKYes, pumping water uphill would work – but youhave to have a hill, and preferably a high one.I think an air-pump system would be moremaintenance-free than a pumping system that hasto deal with the corrosive effects of salt water.NewbeakIs the weight of the piston inside the vanes the onlything supplying force to pump the air down to500 m below sea level?feet2thefireI get a pressure of about 710 psi at 500 m. Youcould have a piston with a cross-section of0.1 square inches (just under 3/16 inch radius)weighing 71 lb. If the weight of the piston were theonly drive, it would need to be prohibitively long,possibly over 65 m if it were made of steel. Soprobably the plan would include some kind ofweight behind the piston. But the rotating partswould still need to seal against approximately710 psi, which is 49 atmospheres. This seems tome to be the killer for the engineering end of it.m.a.king, CanadaRead these comments in full and add your own atphysicsworld.comUsing Mayes’ prefixes, the power of theSun can be written as 0.38 navawatt,while the mass of the galaxy is about220 catagrams (from the Spanish catorce or“fourteen”, denoting 10 42 = 1000 14 ) andthe electron rest mass is 0.91 tisogram.J Keith AtkinUniversity of Sheffield, UKchet1@blueyonder.co.ukUHV-Leakvalvewww.vseworld.comVACUUMTECHNOLOGYGA-6890 LUSTENAU (AUSTRIA),Sandstr.29Tel:+43(0)55 77 -82 6 74Fax:+43 (0)55 77 -82 6 74-7e-mail: office@vseworld.comom14Physics World May 2010
physicsworld.comThe laser at 50Physics WorldDirac House, Temple Back, Bristol BS1 6BE, UKTel: +44 (0)117 929 7481Fax: +44 (0)117 925 1942E-mail: pwld@iop.orgWeb: physicsworld.comEditor Matin DurraniAssociate Editor Dens MilneNews Editor Michael BanksReviews and Careers Editor Margaret HarrisFeatures Editor Louise MayorWeb Editor Hamish JohnstonWeb Reporter James DaceyKate Gardner, Louise Mayor and Dens MilneAdvisory Panel John Ellis CERN, Peter KnightImperial College London, Martin Rees Universityof CambridgePublisher Jo AllenMarketing and circulation Angela GageDisplay Advertisement Sales Edward JostRecruitment Advertisement Sales Chris ThomasAdvertisement Production Mark TrimnellArt Director Andrew GiaquintoDiagram Artist Alison ToveySubscription information 2010 volumeThe subscription rates for institutions are£310/7460/$585 per annum. Single <strong>issue</strong>s are£25.00/736.00/$47.00. Orders to: IOP CirculationCentre, Optima Data Intelligence Ltd, 12/13 CranleighGardens Industrial Estate, Southall, Middlesex UB1 2DB,UK (tel: +44 (0)845 4561511; fax: +44 (0)870 4420055;e-mail: iop@optimabiz.co.uk). Physics World is availableon an individual basis, worldwide, through membership ofthe Institute of PhysicsCopyright © 2010 by IOP Publishing Ltd and individualcontributors. All rights reserved. IOP Publishing Ltd permitssingle photocopying of single articles for private study orresearch, irrespective of where the copying is done.Multiple copying of contents or parts thereof withoutpermission is in breach of copyright, except in the UKunder the terms of the agreement between the CVCP andthe CLA. Authorization of photocopy items for internal orpersonal use, or the internal or personal use of specificclients, is granted by IOP Publishing Ltd for libraries andother users registered with the Copyright Clearance Center(CCC) Transactional Reporting Service, provided thatthe base fee of $2.50 per copy is paid directly toCCC, 27 Congress Street, Salem, MA 01970, USABibliographic codes ISSN: 0953-8585CODEN: PHWOEWPrinted in the UK by Warners (Midlands) plc, The Maltings,West Street, Bourne, Lincolnshire PE10 9PHThe Institute of Physics76 Portland Place, London W1B 1NT, UKTel: +44 (0)20 7470 4800Fax: +44 (0)20 7470 4848E-mail: physics@iop.orgWeb: iop.orgLet there be lightThis <strong>issue</strong> of Physics World celebrates the 50th anniversary of the invention of the laserWhen Theodore Maiman eked out the first pulses of coherent light from a pinkrubycrystal on 16 May 1960, the 32-year-old engineer-turned-physicist at HughesResearch Laboratories in the US could not have imagined that the laser wouldbecome such a workhorse of physics – and so engrained in everyday life. Withinweeks, other physicists – notably those at Bell Laboratories – had reproducedMaiman’s success, with Bell Labs scientists then quickly notching up many otherlaser “firsts”, including the first gas lasers and the first continuously operatingruby lasers.Lasers have gone on to be one of the outstanding success stories in physics. Theycan cool atoms, send data, mend eyes, sharpen astronomical images and probeindividual DNA molecules; they may even detect gravitational waves and triggerfusion. Hardly surprising then that, by our reckoning, some 14 physics Nobel prizeshave been awarded for achievements directly related – or linked – to lasers. Indeed,despite their use in the military, lasers do not suffer from an image problem, beingwidely regarded as a “good thing”.This <strong>special</strong> <strong>issue</strong> of Physics World kicks off by reliving the laser’s first days and bycelebrating its impact on popular culture (think Goldfinger and laser-art shows)and everyday life (DVDs, laser pointers, bar-code scanners). We look at the technologicalimpact of lasers in fibre optics and at the quest for green-wavelengthlaser diodes that could let mobile phones project images onto any surface. Basicresearch gets a look-in, too – in terms of both ultrahigh power and ultrafast lasers.There is a timeline of laser history, while six experts predict where laser sciencewill go next. Online, don’t miss our video interviews with leading laser scientists,while the physicsworld.com blog reveals how we created our cover image and thephoto above. (As it turns out, there are some things lasers can’t do so well.)Matin Durrani, Editor of Physics WorldPhysics World May 2010The contents of this magazine, including the views expressed above, are the responsibility of the Editor.They do not represent the views or policies of the Institute of Physics, except where explicitly stated.15
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