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Summary Talk on Cosmology and Gravitation

XXII Brazilian National Meeting on Partiles and Fields

M.J. Rebouas

CentroBrasileirode PesquisasFsias

Departamento deRelatividadeePartulas

RuaDr. XavierSigaud150,22290-180,Riode Janeiro, RJ,Brazil

Reeivedon29Marh,2002

Theplenaryletures,paralleltalks,oralpresentationsandposterontributionsonCosmologyand

Gravitation presented during the XXII Brazilian National Meeting on Partiles and Fields are

brieyreviewed.Somegeneralremarksarealsopresented.

I Overview and introdution

After four days of listening to two plenary letures,

two parallel talks, a general publi leture, seventeen

oralpresentations,andreading morethanftyposters

related to Cosmology and Gravitation, my hief

im-pression is that the XXII Brazilian National Meeting

on Partilesand Fields(XXII BNMPF) wasa

notie-able sienti meeting, whih overed a great variety

of issues on Gravitation and Cosmology. It brought

together perhaps most of the researhers and

gradu-atestudentsthat haveworkedin thisareainBrazilian

UniversitiesandResearhInstitutes. Thesessionswere

verywellattendedwithafairnumberoflarifying

ques-tions. Ingeneralthespeakersexplainedtheunderlying

ground, approahesand resultsin alearmanner and

keptto the time limits. I thank to them allfor their

quitegoodtalks.

From this and the previous meetings I support

the view that if one onsiders the ontributions

pre-sentedin, e.g.,two suessiveBNMPF meetings they

are rather representative of the researhes that have

beendonein this areain Brazil,and mostofthe

on-tributions reveal a lear emphasis on theoretial and

(or)mathematialaspets ofGravitationand

Cosmol-ogy[1℄.

Theresearhesinmodernosmologyanbebroadly

groupedinvedomains:

i. Astrophysialosmology;

ii. Observationalosmology;

iii. Theearlyuniverse;

v. Cosmitopology(more reently).

Mostof theontributionsto theXXII BNMPF

(orga-nized by the Brazilian Physial Soiety - SBF) were

in the last three families. On the other hand, as far

as I am aware agreat numberof the

observationally-orientedworksonosmologyareoftenpresentedinthe

annual meeting of the BrazilianAstronomial Soiety

(SAB).

I do not share the view that theoretial (and

mathematial)osmology should be stritly relatedto

the observed universe, otherwise it beomes a

point-less exerise. In my evaluation the frontier between

theoretial (and mathematial) osmology and more

observationally-oriented osmology is not and should

not be well-dened, and it is very important that we

have people working on both generalaspets of

mod-ern osmology. However, I feel that a loser

intera-tion between theoretial and observationally-oriented

osmologists is more than desirable | in my view it

is reommendable| forthebenetofboth(physiist

and astophysiist) ommunities. The reentworkshop

alledNewPhysis inthe Spae isertainlyagood

ex-amplein thisdiretion[2℄.

Aonsiderablenumberofabstratsweresubmitted

to the organizers. I envisage how hard was to selet

between oral and poster presentations. A number of

relevant subjets seemed to them to be of interest to

motivate oral presentations, but no doubt other

orga-nizerswould havemadeaquitedierent, andperhaps

equallygood,seletion. Iwillsummarizethepresented

ontributionsbelow,withapologiestotheirauthorsfor

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misrepre-II Plenary and parallel talks

The GeneralRelativity(GR) preditstheexisteneof

gravitationalwaves,andanalysesofexperimental data

obtainedfromobservationsofbinarystarsystemsseem

togivealearevidenethatthesesystemslooseenergy

throughgravitationalradiation[3℄.

Gravitationalwavesare predited notonly by GR

but alsobyothermetrigravitationaltheoriesofsome

generality and sope. However, the harateristis of

gravitational wavessuh as propagation speed,

multi-polarstrutures and polarization statesvaryfrom one

theory toanother. Thus, itis expetedthat its

dete-tionwillprovidearatherrelevanttooltoseletthemost

suitable theory of gravitation [4℄. Further, the diret

observationofgravitationalwavesalsooersthe

possi-bility of testing GR(as well asother metri theories)

in astrongeldlimit,wheretheeetsarenotmerely

a orretion of Newtonian Gravitation. Obviously at

Earththewavesareexpetedtobeweakperturbations,

howeverthey an in priniple provide information on

theonditionsattheirstrongeldsoures[5℄. Further,

thetehnologyneededtodetetaswellas theanalysis

of gravitationalwavesis expeted to open anew

win-dowforobservationoftheuniverse,thusgivingriseto

aremarkableperiodin astronomyandosmology.

BarryC.Barish(CaliforniaInstituteofTehnology)

deliveredalearplenaryleturein theXXII BNMPF,

in whih hepresentedagoodreviewofthenew

gener-ation ofdetetorswithsuitablesensitivitiesfor

detet-ing gravitational wavesfrom avariety of atastrophi

events,suhasthegravitationalollapseofstarsor

o-alesene of ompatbinary systems. He pointed out

that more than forty yearsafter the beginning of the

searh for gravitational waves, several resonant-mass

wavedetetorsare monitoringthe moststrong

poten-tialsouresofsuhwaves(inthekHz band)in our

galaxyandin ourloal group. Thegravitationalwave

detetionoflowfrequenies(inthemHzband)from

spae wasalsobrieydisussed in histalk. Contrarily

to theearthbaseddetetors,forthis typeof detetion

there is anaturaladvantagewhih is thefat that

es-sentiallyallthenoisesduetothegroundareeliminated

(formoredetailsee[6℄).

For some deades sine the disovery of the

os-mi expansionby Hubble [7℄ it wastaken for granted

that thematter ontentof theuniverse wasomposed

of theforms of energy we anreadily detet, i.e., the

ordinary matter and radiation. Suh universe would

expand with a negative expansion rate due to

gravi-tational self-attration of the matter. However, some

yearslater,theoretialaspetsofthestabilityof

galax-iesand starsand surroundinggalaxies) indiatedthat

most of the matter in the universe does not emit or

absorblight (darkmatter). Thedarkmatter lear

in-diationfoundresonanein the1980'sbythe

ination-aryuniversesenarioin whih theuniverseistaken to

be at | the total energy density equal to the

riti-al density

= 3H

2

0

=8G 1:710 29

g=m 3

.

How-ever,measurementsmadeby that time oeredalear

indiationthat the ordinarymatter and the radiation

ouldonly aountfor about 10%of this value|

in-ationseemed to requiredark matter. The new

on-sensus model beame that in whih the universe

on-tainsprimarily old,nonbaryonidarkmatter, and

al-thoughobservationsatthattimeindiatedthatthe

to-tal massdensity wassmallerthan the ritialdensity,

manyosmologistsassumedthattheatmodelwas

rea-sonablywell-established. However,furtherobservations

stronglyindiatedthatthetotalmatterdensitywas

in-deedlessthanhalfoftheritialdensity. Theonlyway

ofhavingsuhalowmassdensityandaatuniverseis

ifanadditional, nonluminousandnonlustering \dark

energy"omponent dominates the universe today,

al-thoughit must havebeennegligible in thepast soas

topermitstrutureformation. Thegeneralrelativisti

Friedmann-Lema^tre-Robertson-Walker(FLRW)

stan-dardmodelingapproahrequiresthatthisdarkenergy

hasanegativepressure,and the reentmeasurements

ofdistantexplodingstars(supernovae)supportthe

ex-isteneofanegative-pressuredarkenergysuhthatthe

(total)energydensityandthe(total)pressurepobey

therelation +3p<0,whihleadsto anaelerating

expansionfortheuniversetoday(forafairlistofbasi

referenesonthetopis I havebriey mentionedhere,

seetheverygoodreviewbyBahalletal. [8℄).

Lua Amendola (Osservatorio Astronomio di

Roma)presentedaverygoodplenarytalk inwhihhe

reviewedhowthereentindependentosmologial

ob-servationsonstrainthevaluesoftheosmologial

den-sityparameters,andhaveindiatedthattheuniverseis

lledwithdarkmatteranddarkenergyandundergoes

anaeleratingexpansion. Hepointedout howreent

supernovae Ia observations [9, 10℄ all for an

aeler-ation expansion of the universe, whih together with

reentosmimirowave,large-salestrutureand

lens-ingdatagivearatherstrongindiationthatthematter

(energy)ontentof theuniverse is basiallyomposed

of darkmatter ( 30%), darkenergy ( 70%),

bary-onimatter (very few perent). For moredetails and

referenesseehis reviewpaperinthisissue[11℄.

OdylioD.Aguiar(INPE)toldusaboutthestatusof

theMarioShenberg gravitation wavedetetor, whih

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erate in 2004. This detetor has a spherialantenna,

willoperateat temperatureoflessthan0:1K,andwill

besensitiveto signalsof amplitude h>10 21

Hz 1=2

inthebandwidth3:0{3:4kHz (formoredetailsonthis

talksee Aguiar'spaperinthisissue[12, 13℄).

It is well known that general relativity is a loal

metrialtheoryandthereforeitseldequationsdonot

xthe topologyof thespaetime, sinegeometry does

notin generalditatethe topology. This freedom has

resulted in a great deal of reent works in whih the

possibilitythat theuniversemaypossessaspatial

se-tionwithanon-trivialtopologyis examined. Whether

weliveinanite orinnitespaeandwhatisthesize

and the shape of the universe are open problems of

topologial nature. Inhis talk HelioV. Fagundes

pre-sented a brief introdution to osmi topology in the

ontextofFLRWmodels, andreviewedthework done

by his group and ollaborators at IFT/UNESP. The

works hedesribedrangefrom early attemptsto solve

aontroversy aboutquasars throughthe multiple

im-agesproduedbynontrivialtopologies,tomorereent

issuessuhasosmirystallographyandquantum

os-mologyinompatuniversemodels(formoredetailson

thistalksee Fagundes'paperinthisissue[14℄).

Before reviewing the oral presentations I remark

that one partiular objetive of the organizers was to

involveasfaras possibletheloal generalpubliwith

themeeting. TothisendtheyinvitedI.Wagatogivea

publi generalleture onosmology, and hepresented

alearandmotivatingleture ontheexpansionofthe

universe[15℄.

III Oral presentations I

The rst oral presentation was of an

observationally-orientedpaperbyM.O.Calv~ao,J.R.T. deMello Neto

and I. Waga [16℄, where it was disussed, through

Monte Carlo simulations, how the Alok-Pazynski

test, as applied to quasar lustering, an be used to

probe the osmologialdensity parametersspae, and

also the equation of state parameter. The approah

disussed in this ontribution may beome a relevant

strategy to narrow down the osmologial parameter

spae.

H.P. deOliveiraand S.E.Joraspresentedanearly

universeontribution,wheretheystudiedtheevolution

oftheentropyandadiabatiperturbationsandshowed

thatforasmallamountofdissipationtheentropy

per-turbations an be negleted, and so the purely

adia-bati perturbations willberesponsible forthe

primor-dialspetrumofinhomogeneities[17℄.

Araujo,S.R.M.M. Roveda andW.Stoeger[18℄)

spher-iallysymmetriperturbationsofFLRWmodelsinthe

so-alledobservationaloordinateswereexamined. The

FLRW (spherial) models areused asthe bakground

spaetime and apartiular ase of spherialdeviation

from this bakground is studied (for more details on

this \observational program"I referthe readerto the

paperbyElliset al.[19℄).

Usingreentobservationalonstraintson

osmologi-aldensityparameters,togetherwithreent

mathemat-ial results onerning small volume hyperboli

man-ifolds and a topologial detetability indiator

intro-dued in [20℄, G.I.Gomeroreportedonaontribution

on osmitopologyin whih itis argued that,by

em-ployingpatternrepetitions, thetopologyofnearlyat

smallhyperboliuniversesanbeobservationally

unde-tetable[21℄. Thisisanimportantresultinviewofthe

fatthatquantumosmologyseemstofavouruniverses

withsmall volumes,and fromtheexpetation,oming

frominationarysenarios,thatthetotaldensity

0 is

likelytobeverylosetoone.

By onsidering that the urrent expanding era

is preeded by a ontrating phase, in other words

by assuming the existene of one boune, N.

Pinto-Netoshowedhowoneanonludethat noobservable

bouneouldpossiblyhavetakenplaeintheearly

uni-verse if GR together with hydrodynamial uids

de-sribe the evolution of the universe, thus under these

onditions theuniverse hasalwaysexpanded (see [22℄

formoredetails).

Therstsetoforalpresentationwaslosedwiththe

presentationbyS.E.JorasofaartilebyR.H.

Branden-berger,S.E.JorasandJ.Martin,inwhihthespetrum

ofsalareldutuationsinabouningasymptotially

atuniversewasalulated,andthedependeneofthis

result onlengthsales shorter thanthe Plank length

wasinvestigated(formoredetailssee[23℄).

IV Oral presentations II

Topologialdefetssuhasmonopoles,stringsand

do-mainwallshavebeenstudiedindierentontextssuh

astounderstandtheprimordialuniverseandstruture

formationin theearlyuniverse. Theirnature depends

uponthetopologyofthevauum manifoldoftheeld

theoryunderonsideration. Theseondsetoforal

pre-sentationsbeganwithaontributionbyR.M.Teixeira

FilhoandV.B.Barbosa[24℄,wheretheyhaveobtained

intheontextofsalartensortheoriesthegravitational

eld of a global monopole, in the weak-eld

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S.S. e Costa delivered a ontribution related to

osmi topology in whih general solutions of the

Helmholtzequation, inseveral oordinatessystemsfor

twoandthree-dimensionalhyperboli,spaeswere

pre-sented[25℄.

Another ontribution related to osmi topology

was an artile by D. Muller, H.V. Fagundes and R.

Opher[27℄,wheretheyhavestudied,throughnumerial

alulations,theCasimir(vauum)energyfora

onfor-mally oupled,massivesalareldin astatiuniverse

whosespatialsetionsareendowedwiththetopologyof

the smallest known hyperbolithree-manifold (Weeks

manifold). Theyhaveonludedthatthereisa

sponta-neousvauumexitationoflowmultipolaromponents.

A. Bernui alsopresentedaosmi topology

ontri-bution in whih the osmi rystallographystatistial

approah to the topologial signature of the universe

wasused inhis numerialsimulationswithinomplete

atalogs.

R.Androvandipresentedaninterestingontribution

(R. Aldrovandi, J.Garieland G.Marilhay)onwhat

theyallthepre-nuleosynthesisperiod(PNS period),

betweenz 10 10

and z 10 15

, and where our loal

physisdoesnot neessarilyhold. A generaloverview

of physialproblemsappearinginthePNSperiod was

given,andpossibleunderstanding forthestriking

out-omes weredisussed. Formoredetailssee [26℄.

V Oral presentations III

Condensed mattersystemssuh aslightinmoving

di-eletrisand quasipartilesin amovingsuperuidan

beused tomimi kinemati aspetsof general

relativ-ity. The omparative study between the kinematial

aspetsofGRandotherkindsofinterationshasbeen

alled analog model for gravitation or simply analog

gravity. Thesetypesofanalogmodelsarerather

impor-tantin that, e.g.,theyprovideblak holeanalogsand

mayleadtoexperimental testof quantum eld theory

in urvedspae. Thelast set oforal presentations

be-ganwithabriefreviewtalk,deliveredbyR.Klippert(a

workinollaborationwithV.A.deLoreni)where

ana-log gravitymodels were disussed in several ontexts,

ranging from eletrodynami in non-linear media [28℄

to movingdieletrisandaoustiperturbations(fora

fairnumberofreferenesonthistopi see[29℄).

AworkbyJ.M.FMaiaandJ.A.S.Limainwhiha

proeduretogenerateosmologialsolutionsinthe

on-text of GRwhose matter ontent is given by asalar

eld plus a perfet uid waspresented. Appliations

to inationary and quintesseneosmologieswere also

A.Y. Miguelote reported on the results of an

ar-tile in ollaboration with M.F.A. Silva, A.A. Wang

and N.O. Santos, in whih some properties of the

Levi-Civita(LC)typeofsolutionsofoupled

Einstein-Maxwellequationsarestudied,andsomelimitsofthis

type of solution are obtained together with an

inter-pretationofthefreeparametersinvolvedinLCtypeof

spaetimes[31℄.

I.D. Soares presented a interesting paper

(homo-lini haos in the dynamis of a general Bianhi IX)

ofa work in ollaborationwith H.P. Oliveira, A.M.O.

Almeida, and E.V. Tonini, in whih they have

stud-ied the dynamis of anisotropi (three sale fators)

BianhitypeIXmodelwithdustandosmologial

on-stant(positive). Theyhaveexaminedthe existeneof

haosin thismodel,andhaveshownthat itishaoti,

andthat the haos hasahomolini nature. The role

playedbytheosmologialonstantinthephasespae

is shown to be ruial in that it determines both the

existene of a saddle-enter-enter ritial point, and

theritialpoints atinnityorresponding to the

De-Sitteronguration. FormoredetailsIreferthereader

toref.[32℄.

The interation of Hawking radiation and a stati

eletriharge was aontribution deliveredby L.C.B.

CrispinoofaworkinollaborationwithA.Higuhiand

G.E.A.Matsas,in whih theyhaveinvestigatedintwo

interating situations whether the equality found for

theresponseofastatisalareldismaintainedinthe

aseofeletriharges(see[33℄).

The last oral presentation was by J. Casti~neiras

(a work in ollaboration with L.C.B Crispino, G.E.A.

Matsas and D.A.T. Vanzella). They have studied

\free partiles" for whih E < m 2

outside

Reissner-Nordstromblakholesandin aspaetimeofastar(for

moredetailssee [34℄).

VI Panel ontributions

Morethanftyontributionswerepresentedasposters.

About twenty per ent were related to the physis

of the early universe. F.G. Alvarenga, J.C. Fabris,

G.A. Monerat and N.A. Lemos presented two

ontri-butions on quantum osmology [35℄. N. Pinto-Neto

and E.S. Santini also presented a poster related to

quantum osmology (see in this onnetion the

arti-le [36℄). Three works onneted to the preheating

proess were presented as posters: one by S.E. Joras

and V.H. Cardenas [37℄; a seond by A.H. Campos,

R. Rosenfeld and J.M.F. Maia; and another by R.O.

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a seond by H.P. de Oliveira alone [38℄, and a third

by J.C. Fabris, A.M. Pelinson and I.L. Shapiro [39℄.

A.H.Campos,R.Rosenfeld, J.M.F.Maiaand H.Reis

disussedin aposterthepossibleprodutionof

super-heavy primordial partiles. R. Aldrovandi, A.L.

Bar-bosa,M.Canadaand J.G.Pereirapresentedaposter

onkinematisofaspaetimewithinniteosmologial

onstant(!1) andspeedoflight(!1),whose

results may be of someinterest to early universe

os-mology[40℄. Aposterwithsomeontatwiththeearly

universe was also brought to the meeting by M.G.C.

Batista.

Nineontributions relatedto topologial defets in

dierent ontexts were presented as posters. Three of

themtreatedthesedefetsinsalar-tensortheories: one

byV.B.Bezerra,L.P.Colatto,M.E.X.Guimar~aesand

R.M.TeixeiraFilho[41℄;anotherbyV.B.Bezerraand

C.N. Ferreira [42℄; and athird by V.B.Bezerra, R.M.

TeixeiraFilho, G.Grebot andM.E.X.Guimar~aes[43℄.

Thebehaviourofnonrelativistiquantum partiles

in-terating with dierent potentials in the spaetimes

generated by a osmi string and also by a global

monopole weredisussedin aposterbyG.deA.

Mar-ques and V.B. Bezerra [44℄. Two posters on osmi

strings were presented: oneby A.A. Moregula in

ol-laboration with M.M. Som, and another by V.A. de

LoreniandE.S.MoreiraJr(see[45℄). Thesolutionsof

Shrodinger equations for the Coulomb and harmoni

osillator potentialin the osmi-stringonial

spae-times of N dimensions were presented in a poster by

J.L.A. Coelho and R.L.P.G. Amaral [46℄. T

opologi-al defets in the ontext of(or related to) ondensed

matter were disussed in two posters: one by C.A.L.

Ribeiro,C.FurtadoandF.Moraes,andanotherbyJ.F

deAssis,V.B.BezerraandC.Furtado.

BesidesFagundes'paralleltalkandtheoral

presen-tationsbyG.I. Gomero,S.S.eCosta,D. Muller etal.,

and A. Bernui, wehad an additionalposter

presenta-tion by G.I. Gomero of a work in ollaboration with

M.J. Rebouas and R. Tavakol [20℄ on the

detetabil-ity of osmi topology of nearly at FLRW universes

in the light of the most reent observations (Sne Ia,

largesalestruture(LSS)observations,MAXIMAand

BOOMERANG).

In addition to BarryC. Barish'splenary talk,and

O.D. Aguiar's parallel talk, four posters related to

gravitationalwaves were presented: K.L. Ribeiro and

O.D. Aguiar; S.R. Furtado and O.D. Aguiar; and

L.A. de Andrade, O.D. Aguiar andK.L. Ribeiro; and

also C. Frajua, N.S. Magalh~aes, O.D. Aguiar, K.L.

Ribeiro, L.A. de Andrade, W.F. Velloso Jr and J.L.

Melo(see[47,48℄).

One by T. Vargas on Regge Calulus in teleparallel

gravity,andthreeothersbyA.A.SousaandJ.W.Maluf

(formoredetails see[49,50℄).

Itseemsindisputablethatmostoftheoretial

physi-istsspendalargeamountoftheirtimeinarryingout

nonnumerialulationofonesortoranother,mostof

whih are algorithmior semi-algorithmi. Today the

omputer algebra(CA) systems are standard toolsof

theoretialphysiistsforperformingsymboli,although

inmostasesperhapstheysimplydonotmentionthis

fat. We had three CA poster ontributions in the

meeting, all related to the Maple system. One dealt

with the symmetry groups in GR (by J.A.F. Roveda

andJ.E.F. Skea), whih isarelevantpiee of

informa-tionneededin theinvariant(loal) haraterizationof

spaetime;andanotherwasabouttheusageofMapleto

alulate quasi-normalmodesofradiatingsystems(by

P.C.C.MonteiroJrandJ.E.F.Skea). F.D.Sasse

deliv-ered a ontribution in ollaboration with R.F.

MLe-naghan and S.R. Czapor where the Maple pakage

NPspinor was used to prove the Hadamard's

onje-ture for the salar wave equation in Petrov type III

bakgrounds.

Dierent aspets and ontexts of blak holes were

disussed in a series of four posters. G. de Oliveira

Neto studied exat solutions of Einstein's equations

in (2 +1)-dimensions whih, depending on the

val-uesofertainparameters,mayrepresenttheformation

of blak holes [51℄. A.A. Sobreira and V.B. Bezerra

examined rotating blak hole in Einstein-Fokker

the-ory in (2+1)-dimensions. Holonomies in the (2+

1)-dimensional geometry of blak holes were the ontent

ofaposterbyA.Carvalho,C.FurtadoandF.Moraes.

A blakhole typesolution ofEinstein equationsin

2-dimensionswasdisussedbyD.G. Delfrate.

There were four posters whih I broadly grouped

asgravitational-relatedworks. M.Caladapresenteda

posterongravitationandtheloalsymmetrygroupof

spaetime [52℄. A.A.Sousaand J.W. Malufpresented

aposterwhere theyproposed anexperimentaltestfor

the gravito-magneti eet. R.C. Rigitano disussed

inaninterestingposterthegeometrirepresentationof

generallineartransformations,andthepossibilitiesand

limitations ofthe representationof ovariant

transfor-mations. C.R.Munizexaminedgeometripropertiesof

thespinintheontextofGR.

Two posters were related to Astrophysis. In one

the third post-Newtonian dynamis of ompat

bina-riesequationsofmotionwasdisussedbyV.Andrade,

L. Blanhet and G. Faye (for detail see [53℄). In

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librium ongurationswith spherialsymmetry (King

models)[54℄.

M.D.Maiapresentedaninterestingposter(related

totwoworksinollaborationwithE.M.Monte [55,56℄)

in whih he showedhowbrane-worldosmology oers

aquitesimpleexplanationfordarkenergy.

M.E.X.Guimar~aes,L.P.ColattoandF.B.Tourinho

presentedaposterin whihtheyextendedto the

on-textofsalar-tensortheories[57℄(wheretheparameter

! in no longer onstant) a proedure, devised by A.

Barrosand C.Romero[58℄, whih makeslearhowto

obtain solutions in the Brans-Diketheory from

solu-tionsinGRforthesamematterontentwhenone

on-siderstheweak-eldapproximationsin boththeories.

In an interesting poster by S.O. Mendes and R.

Opherit wasdisussedhowthe1=r 2

gravitationallaw

onsubmillimetrisaleanbeusedtotestthemodied

Newtoniandynami theory(MOND)[59℄.

Besidesthebriefreviewtalk,presentedbyR.

Klip-pert as an oral presentation, Analog Gravity also

ap-peared in a poster by V.A. De Loreni and R.

Klip-pert[28℄.

AninterestingposterwaspresentedbyF.P.

Deve-hi and G. Kremer in whih the kinetitheory of

rel-ativistigasesin two-dimensionalspaewasdeveloped

toobtainthermodynamialquantitiesin2-dimensional

osmologialmodels[60℄.

H.P.deOliveiraandI.Dami~aoSoarespresentedin

aontributiontheresultsoftheirstudiesofthe

dynam-is ofspheriallysymmetrigravitationalollapseofa

masslesssalareld [61℄. H. P. deOliveira,I.Dami~ao

Soares and E.V. Tonini also had a poster where they

presentedananalytialmethodtodesribetheunstable

periodiorbits oftheenter manifoldfor Hamiltonian

systems. Anotherposterwithsomerelationtothiswas

presentedbyO.C.Castellani,G.A.MoneratandJ.F.V.

Roha.

M.M.deSouzalaimedinaposterthattheonstant

anomalous radialaelerationobserved in thePioneer

10and11spaeraftsanbeexplainedintermsof

dis-reteinterations(fordetailsee[62,63℄).

J.F. Villas da Roha presented a poster in whih

solutionstoEinstein'seld equationsinN-dimensions

withspherialsymmetryweredisussed[64℄.

L.SandovalJronsideredinaontributionthe

on-straints on generalized metris (with both symmetri

and antisymmetri parts) desribed throughvierbeins

imposedbybosonistringsinurvedspaetimes.

M.L. Bedran presented an interesting pedagogial

posteromparingtheDoppler(speialrelativity)eets

withtheosmologialredshiftofgeneralrelativity.

F.D. Sassereviewedthedierentinterpretationsof

fermions in a storage ring in a Serret-Frenet tetrad

frame,insteadoftheusualHehl-Niframe.

M.J. Lazo and S. Ragusa showed how to

alu-latetheeletromagnetiangularmomentumemissionof

fourthorder,extendingthereforethealulationsmade

in the Landau-Lifhitz book for eletridipole. They

intend to use a similar sheme to examine analogous

gravitationalemission.

Tolose this setion I remark that a onsiderable

numberofextended versions oftheworkspresentedin

theXXIIBNMPF willbeavailable(proeedingsofthe

meeting)andanfairlysoonbeobtainedviadownload

fromtheBrazilianPhysialSoiety(SBF)webpage. So,

formoredetailsonsomeofworksbrieyreviewedhere,

Ireferthereadertothat site[65℄.

VII Closing remarks

The large number of abstrats submitted to the

Cos-mologyand Gravitation sessionsof theXXII BNMPF

isertainly indiativeof the robustlevelof interestin

the area. The meeting was a lively one and

demon-stratedthevitalityofaextensivesetofresearhtopis.

Italsowasveryinformativeandmanydisussionstook

plaeintheregularsessions,andalsointheoeeand

othersbreaks. Thespirit ofollaboration,essentialto

theprogressofsiene,waspresentinthesessionsand

disussions.

Let me lose my review by strengthening a point

I have indiated in the introdution, whih is that

the interation and ollaboration between

theoreti-alandobservationally-orientedgravito-osmologistsis

stronglyadvisablefortheadvaneofthearea,the

ben-et of our ommunity as well asfor the formation of

Brazilian young sientists in Cosmology and

Gravita-tion.

Aknowledgments

IwouldliketothanktheOrganizingCommitteefor

theinvitationto deliverthesummary talkon

Gravita-tionandCosmologyoftheXXIIBNMPF.Ialsothank

them for the large amounts of eort put into the

or-ganizationof a very suessful meeting. I thank Ioav

Wagafor hishelp in thelassiationofthetopis for

my summary talk. Some authors provided me with

preprints, reprints or referenes related to their

sub-mittedabstrats. Theadditionalinformation material

provedto be veryuseful forme, and I thankall these

olleagues for their helpful gesture. I also thank

(7)

thank CNPqfor thegrant under whih this workwas

arriedout.

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