Sothere's been a newstorygoingaroundtheBritishmediaabout a carmeltinginLondon, whichapparentlyusedyoutoitsproximityto a newbuilding, whichisgoingupinLondon.
Thephysicsis a thingcalledgeometricoptics, andthisisabouthowyoudowithunderstandinghowlikepropagates.
Butjustbecauseitlooks a littlebitlikeanoldfashionedworkingtoe.
Sotheissueisthat a concavesurfaceisessentially, ah, wayofconcentratinglightAkaneCave, especially.
I mean, I guesstheimportantpointisthatiftheifthesunlightthatwerehittingthissurfacealljustwentintothebuilding, thatwillbefine, becausethebuildingwouldhavenorealeffect.
Andthenyoucoulddothisthingcalled a tracingofessentiallyfiguringoutwherethedifferentbitsofsunlightwillgo.
Justusingthesesimplelawsofgeometricopticsofthelighttravelingin a straightlineunlessithitsthesurface, andthentheimportantlawyouhavetousehereisthelowerreflection, whichjustbasicallysaysthattheangleofincidenceisequaltotheangleofreflection.
Startedfiguringoutwherethelightwhenjustdoingitwith a pencilontheprotractor, oneofthesethingsformeasuringangles.
Andactuallythehardestpart.
Thiswasfinding a protractorbecausenoonehaswonanymore.
But I didactuallymanagetoborrowone.
Okay, soactually, I actuallywentroundallthestudentssaying, Can I borrow a protractor?
Thegeneralresponse I gotwasWhat's a protractor, whichhasbeenworryingbutactuallyturnedout.
Oneofthemhadthisratherfancylookingprotractedstuckontheendof a rulerinhisdesk.
Sohere's what's goingonatthatparticulartimeofday.
Sohere's thesunlightcomingin, andthesun's a longwayaway, whichessentiallymeanstheraysofallparallelcourse, therazor, a sortofdivergingfromthesunindifferentdirections.
Andsoyoucanseetheneteffectisthatallthiswillspreadoutsunlightcominginendsupconcentratedin a rathersmallarea.
And I didsomevery, verycrudecalculationstotryandfigureouthowmuchit's concentratedby.
I reckonit's probablyabout a factorof 10 to 20 sothattheintensityoflightonthatparticularlittlebitofroadwasabout 10 to 20 timeswhattheusuallyintensityofsunlightis.
HavingcreatedanurbanmythhereinNottinghamontheurbanmyth I createdisinthemiddleofNottingham, thisthingcalledtheSkyMirror, whichis a beautifulpieceofart.
It's a conchaidmirrorputtherebyanartistcalledInitialKapoor, whomakesthesekindofinstallationsquite a lot.
Aboutsixmetersindiameter.
It's a largeconcavemirroranditbasicallyreflectsthesky.
SowhenyouwalkintothissquareoutsidetheplayhouseinthemiddleofNottingham, youseethisamazingmirrorbasicallyreflectingtheskylineintheskyaboveyouandyougettheseniceinvertedimageisoneofthepropertiesof a concavemirroristheimagescomeoutupsidedown?
You'restilltalkingaboutmany, manykilowattsofpower, potentiallybeingconcentratedinto a verysmallregion.
Soyoureallygottabeverycarefulaboutit.
Itturnsoutinthisparticularcasethatthey'rebeingquitecleveraboutcitingit, soit's not a hugeissue.
Sounliketheskyscraper, whereit's a southfacethat's reallyfacingthesun, thismirrorisdesignedtofaceNorth, whichreallymeansyouvery, reallygotgetdirectsunlightonit.
Butthereare a fewweeksoftheyearinthemiddleofsummerwhenthesuncreepsaroundfarenoughthatyoudohavetoworryaboutit.
Andso I warnedthemaboutalltheseissues, andtheyactuallythendecidedthattheyweregonnaputintomitigation, whichwastoputsomesunshadesuponthetopofthetheater a zawayoff, preventingthesunlight, gettingontothefrontfaceofthemirror.
Anditwas a Fridayafternoonand I was, youknow, fairlylaidbackwithmyfeetuponthedesk, talkingtothisreporteronjustinpassing.
I said, Yougottabeverycarefulaboutthesethingsbecauseifyouweren't, then a passingpigeoncouldendupbeingbarbecuedasitflewthroughthebeam.
Andclearlyitwas a slownewsdayinNottingham.
Sothisendedupbeingthebannerheadlineonthefrontpageofthenewspaperaboutbarbecuepigeonsandtheguysonthewireservice, naturally, whogothrough a llthelocalnewspaperslookingforentertainingstories.
Andtheypickeduponthisone.
Andsotheyputitoutonthewireservicenationallyandinternationallyandclearlyitwas a slownewsdaynationallyandinternationally, and I endedupbeinginterviewedontheBBCandthestoryappearedinAustralianewspapers, anditwasallovertheplace.
Andactually, thechefinthePlayhouseCausesRestaurantintheplayhousehasclearlyhad a senseofhumorbecauseheputbarbecuepigeononthemenu.
Buteventhatwhat, 10 yearsafterthis, I still, oncein a whilepeoplehearpeopletalkingaboutthismirrorbarbecuingpigeons.
I reallyhavecreatedmyveryownurbanmyth.
Sothere's been a newstorygoingaroundtheBritishmediaabout a carmeltinginLondon, whichapparentlyusedyoutoitsproximityto a newbuilding, whichisgoingupinLondon.