home bbs files messages ]

Forums before death by AOL, social media and spammers... "We can't have nice things"

   sci.physics.research      Current physics research. (Moderated)      17,516 messages   

[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]

   Message 16,173 of 17,516   
   Jos Bergervoet to Jonathan Thornburg   
   Re: A question about spherical gravitati   
   12 Jun 18 11:57:10   
   
   From: bergervo@iae.nl   
      
   On 6/12/2018 11:22 AM, Jonathan Thornburg wrote:   
   > In article , I wrote:   
   >> In (crude, but still useful) ASCII-art, we thus have   
      ...   
     ..   
   > Making the same correction to my 2nd diagram suggests that it should   
   > have looked more like this:   
   >   
   >          t                        O marks the dust cloud   
   >         /|\   
   >          *      :                 * marks the singularity   
   >          *      :   
   >          *      :                 : marks the event horizon   
   >     t=Z  *      :                   (which is also the trajectory   
   >          *O     :                   of a light flash emitted at   
   >          *OOOO  :                   the event $(t,r) = (X,0)$)   
   >     t=Y  *OOOOOO:   
   >          *OOOOO:OOOO   
   >          *OOOO:OOOOOOO   
   >          OOO:OOOOOOOOOOO   
   >     t=X  :OOOOOOOOOOOOOOOO   
   >          OOOOOOOOOOOOOOOOOOO   
   >          OOOOOOOOOOOOOOOOOOOO   
   >          OOOOOOOOOOOOOOOOOOOOO   
   >          OOOOOOOOOOOOOOOOOOOOOO   
   >     t=0  OOOOOOOOOOOOOOOOOOOOOO----> r   
   >          |      |   
   >         r=0    r=2M   
      
   Can we extend this towards late time (when the event horizon   
   vanishes by evaporation?) For instance like this:   
      
              t   
             /|\   
              |   
         t=U  *:   
              * :   
              *  :   
              *   :   
              *   :   
              *    :   
              *    :   
         t=Z  *     :   
              *O    :   
              *OOOO  :   
         t=Y  *OOOOOO:   
              *OOOOO:OOOO   
              *OOOO:OOOOOOO   
              OOO:OOOOOOOOOOO   
         t=X  :OOOOOOOOOOOOOOOO   
              OOOOOOOOOOOOOOOOOOO   
              OOOOOOOOOOOOOOOOOOOO   
              OOOOOOOOOOOOOOOOOOOOO   
              OOOOOOOOOOOOOOOOOOOOOO   
         t=0  OOOOOOOOOOOOOOOOOOOOOO----> r   
              |      |   
             r=0    r=2M   
      
      
   I'd expect the singularity vanishes where the horizon also vanishes   
   (even if it formed a bit later than the EH in your drawing).   
      
   And would that be the same as a Penrose diagram with the   
   r=0 line shifted to the right at late times? (To keep the   
   horizon at the light-like slope all the time, I mean..)   
      
            z|\   
            z|  \   
            z|    \I+   
            z|      \   
            z|        \   
            z|          \   
   sssssssh/           /   
         h/           /   
       h/           /   
     h/           /   
   z|          /   
   z|        /   
   z|      /I-   
   z|    /   
   z|  /   
   z|/   
      
   where z denotes the center of space, s the singularity, and   
   h the event horizon.   
      
   So what would the region above the singularity mean?   
      
   --   
   Jos   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]


(c) 1994,  bbs@darkrealms.ca