The Official Publication of the Consortium of Multiple Sclerosis Centers and Rehabilitation in Multiple Sclerosis MSInternationalJournal of CARE

progressin the globalsearch forgravitationalwaves. ThethreeLIG O interferom etershavebeen carryingoutnearly continuousobservationsattheir design sensitivity for the 5th Science Run (S5),joined for substantialperiods by the G EO 600 interferom eter. S5s goalof one years worth ofcoincident data willsoon be achieved. discussions were held between the LIG O Laboratory and the LIG O Scienti(cid:12)c Collaboration (which includes the m em bers of G EO ) and V irgo and EG O (the European G ravitationalO bservatory which operatestheV irgo interferom eter)on arrangem entsforjoint observing and data analysis.Thosediscussionscam eto a successfulconclusion,asm arked by two eventsin 2007:thesigning ofa M em orandum ofU nderstanding laying outtheagreem ent to observe and analyze data together,and then,on M ay 18,2007,the startofthe (cid:12)rstV irgo Science Run (V SR1)in coordination with LIG O sS5. Theagreem entservesasa m odelforglobalnetwork analysisofdata from allgravitational wave detectors, as they com e on line. The basic structure is not a m erger, but instead a com m itm ent from independent projects to work together on both the operation oftheir on data analysis.The collaboration on data analysisisespecially close.Except for closing out ofpapers on pre-agreem ent observations,allanalysis willbe carried out by jointteam s,and willbe published in papers bearing the nam es ofthe m em bers ofallofthe projects. energy is a surprisingly di(cid:14)cult problem in generalrelativity. Forinstance,the energy density ofthe gravitational(cid:12)eld ofa planetata particularpointcould be determ ined by a com oving observer m easuring the kinetic energy ofa freely falling object. D ue to the equivalence principle,both the object and the observer fallat equalrates. Therefore, the observer would notassign any energy to the object. O therobservers like an observer who is at rest with respect to the planet would m easure di(cid:11)erent values. This raises the question ofhow energy depends on the choice ofan observer which violates the philosophy ofgeneral relativity whose tensorialequationsare independent ofthe used reference system In ics the stress-energy tensor is a m easure ofthe energy and m om entum the electrom agnetic due to a source distribution . A sim ilar in generalrelativity so-called Bel-Robinson T which can be thoughtofasbeing induced by a stress-energy tensor T (cid:22)(cid:23) .Itsphysicalm eaning however rem ainsunknown itdoesnoteven have unitsofenergy density.Thisisa con-sequence ofthe equivalence principle which equates the gravitationalm ass (the "charge" of gravity)with theinertialm ass.Thesourceterm ,i.e. (cid:22) in electrodynam icsand T (cid:22)(cid:23) in relativity,doesnotcontain the energy ofthegravitational(cid:12)eld.H owever,since the equations ofgeneralrelativity The interest in cosm ic string (CS) research has seen a renewalrecently when it was ob-served thatfundam ental(super)stringscould actasactualtopologicaldefects,although with possibly rather di(cid:11)erent properties. It was even said,obviously in an excess ofenthusiasm , thatthe observation ofa single cosm ic string in the sky would be \a proof" ofthe existence ofsuperstring theory! This article should perhaps begin with a disclaim er: when we talk about‘m ountains’on neutron stars we speak not ofprecipitous projections from the surface,but rather oflarge scalem assasym m etries.O verthelastdecadea seriesofpapershasappeared in theliterature attem pting to calculatejusthow largesuch m ountainsm ightbe.Thereisa strong m otivation behind this:In a spinning starsuch asym m etriesdirectly source gravitationalwave em ission, and with theLIG O and G EO 600detectorsup and running,and V IRG O closebehind,accurate m odeling ofthis class ofpotentialsource is vital. A s em phasized recently by O wen (2005), having estim ates ofpossible m ountain sizes enables us to assess the signi(cid:12)cance not just of gravitationalwave detectionsbut(currently m ore usefully!) of upper bounds ,telling uswhen the physics atleastwould perm ita detection. on G eneralRelativity and G ravitation and the G ravitationalW aves O on theSydney Convention and Exhibition Centeratspectacular D arling H arbour. There were 15 plenary talks and 55 parallelsessions. A typicalday had one \A m aldi" and two \G R" plenary talksand there were (cid:12)ve \G R" and only one \A m aldi" parallelsessions in the afternoon. The form atwas a bitofa departure from the tradition of A m aldis,where in the pastthere wasno division between plenariesand parallels. the the m ittee ofthe InternationalSociety ofG eneralRelativity m et. A m ong othertopics,theresultsfortheelection ofthepresidentofthesociety wereannounced, A bhay A shtekar elected. The next venue for the G R conference was also selected,the responsibility going to a proposalfrom a group ofM exican institutionsto hold theconference at the Banam ex conference center at M exico City. The G ravitationalW aves International Com m ittee (G W IC)also m etbefore the conference started,and am ong otherthingsdecided the venue for the next A m aldiConference,choosing Colum bia U niversity in N ew York for 2009 am ong severalcontenders. loop a Interferom pass particle astrophysics. gravity,string theory cosm transcend individualareas. exploring the universe allfour ature:stronginteractionsthrough thePierreA The W ashington U G ravity G roup hosted a dynam ic and exciting m eeting in St. Louis entitled \N um ericalRelativity m eets 3PN :A W orkshop",from February 8-11,2007. In attendance were m any ofthe leading researchersin the (cid:12)eldsofnum ericalrelativity,post-N ewtonian theory,and gravitational-wave data analysis. The purpose ofthe m eeting wasto bring these researchers togetherin an e(cid:11)ortto stim ulate progress atthe im portantinterface between these (cid:12)elds. The workshop was organized with a set ofinvited talks each m orning, designed to probe the centralquestions and problem swith am ple tim e fordiscussions. Each afternoon started with a sm allnum ber ofshortcontributed talksfollowed by an open ended working/discussion session focused on a di(cid:11)erent topic each afternoon. The workshop program can be found athttp://nrm 3pn.wustl.edu/.Below,we sum m arize the highlightsofthe m eeting and attem ptto give propercreditto individuals and the groupsthey represent. W e apologize for any errors or om ission,and for the fact that we cannot m ention everyone who contributed to thisvery successfulm eeting.