7/30/2019 PCVaidya

1/6

In1998,Isubmittedtwopapersentitled

1. ``FinalStateofSphericalGravitationalCollapseandLikelySourceofGammaRayBursts:A. Mitra (arXiv:astroph/9803014)

2. ``TowardstheFinalStateofSphericalGravitationalCollapseandLikelySourceofGammaRayBursts

A. Mitra (arXiv:astroph/9803013)ToPhys.Rev.Lett.Thesetwopapersfirstclaimedthatforphysicalgravitationalcollapse,no

trappedsurfaceorblackholeisformedinfinitepropertime.Ontheotherhand,the

collapsingobjectlosesmassenergyinsuchamannerthattrappedsurfaceformationis

avoidedandasymptotically,forcontinuedcollapse,thecollapsingstarwouldtendtobea

zeromassBlackHole,theborderlinebetweena``NakedSingularityanda``BlackHole

PRLrefereecommentswerebetterthatwhatIhadexpected;ofcoursetheywerenot

accepted.ThenIsentthemtoProf.P.C.Vaidya,whostartedtheconceptofradiative

physicalgravitationalcollapse.LaterImethiminperson.Hefoundmymanuscripttobe

alrightbothmathematically&physically.Iamverygratefultohim.

Hereisthetextofhisresponsesansmaths.

7/30/2019 PCVaidya

2/6

Prof.P.C.Vaidya 34Shardanagar

TelNo:(079) 6610893 Ahmedabad380007

May4,1998

DearDrMitra,

YourspeedpostletterreachedmeonMay2nd,yourconclusioninthefirstpaperthatattheendofthe

gravitationalcollapse,allthematterofthecontractingsphereisconvertedintoradiationremembered

meofsomeearlierwork.ThefirstparagraphofanotepublishedinCurrentSciences28,399(1959)[a

reprintofwhichisenclosedherewith]isreproducedbelow:

``FollowingVaidya1,Raychaudhury2 firstconsideredthecaseofamassparticlebeingcompletely

annihilatedandconvertedintoradiation.Hefoundthatsuchaprocesscouldnotbeadequately

describedbythefieldequationsofGTR(GeneralTheoryofRelativity).However Israel3 foundthatthe

relativityequationsareadequatetodescribesuchaprocessofcompleteconversionofamassparticle

intoradiationandhehasgivenamodelforthesame.

(Ref:Vaidya1,Raychaudhry2,andIsrael3willbefoundintheattachedreprint)

So,onethingisclear.Mathematicallyyouareonrightlines.

IhavegonethroughyourfirstpaperaswellyourreplytoRefereeA.Asfarasmathematicalconceptsare

concerned,Iamsatisfiedthatyouseemtobecorrect.PleaselookintoIsraelspapermentionedabove

asacheckonthispoint.

AsregardsremarkofRefereeAinmyfirstsentenceofPARA4,Iwouldsaythat:

ForradiationflowinginemptyspaceEij=qk

ikjwherek

iisnotonlyanullvectorbutageodesicvector

i.e.,

(MathsOmitted)

Butforradiationflowingthroughmatter,thetracksofflowingradiationarenullcurvesallrightbutthey

arenotnullgeodesics.ThusinteractionofradiationwithmatteristakencareofinthegeometryofGTR

bypostulatinganonzeroaccelerationofphotons(ki;kj 0).Thecoefficientin(4)willincludetheeffect

ofinteractionofmatterwithradiationflowingthroughit.

ImayaddthatIhavederivedanexactsolutionofEinsteinEquationsofGRTdescribingsphericalgravitationalcollapseinwhichradiationisflowingout.ThepaperispublishedinAstrophysicalJournal

Vaidya,P.C.,ApJ144,943(1965)

Idonothaveanyreprintsofthatpaperleftwithmenow.

7/30/2019 PCVaidya

3/6

YouwillseefromthisletterthatIammoreamathematicianthananastrophysicistoranastronomer

(Seeattachedreprintentitled:``Me,anAstronomer!)

AndsomyopinionisthatyourtreatmentofEquationsofGRT,theirsolutionsandinterpretationsof

solutionsallappearsoundtomemathematically.

Wishyouallthebestinyourendeavours

Yourssincerely

P.C.Vaidya (Signature)

7/30/2019 PCVaidya

4/6

7/30/2019 PCVaidya

5/6

7/30/2019 PCVaidya

6/6