Groups > sci.physics.relativity > #474434

Re: Freefall reaches light speed at a black hole

Newsgroups	sci.physics.relativity
Date	2018-10-07 22:32 -0700
References	(4 earlier) <93a843e7-6e35-57ad-42db-b03d902e9688@PointedEars.de> <81e9a959-7dfb-4321-869f-0f7a341a6640@googlegroups.com> <b933d0c1-7d98-3781-4e5b-28ab594891f0@PointedEars.de> <c8cd67c1-8e97-47b6-b2ab-8e4e38ee1ec8@googlegroups.com> <a477aaa8-bf2b-d564-f8aa-fddd1e063116@PointedEars.de>
Message-ID	<effdfac5-008c-4fef-a160-68c072831eda@googlegroups.com> (permalink)
Subject	Re: Freefall reaches light speed at a black hole
From	JanPB <filmart@gmail.com>

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On Sunday, October 7, 2018 at 3:19:27 PM UTC-7, Thomas 'PointedEars' Lahn wrote:
> JanPB wrote:
> > On Sunday, October 7, 2018 at 7:47:20 AM UTC-7, Thomas 'PointedEars' Lahn wrote:
> >> JanPB wrote:
> >>> [bla]
> >>
> >> Si tacuisses, philosophus mansisses.
> >>
> >> <https://arxiv.org/abs/gr-qc/0411060v2>
> >>
> >> Am.J.Phys.76:519-532,2008 (peer-reviewed)
> >> (Submitted on 12 Nov 2004 (v1), last revised 31 Aug 2006 (this version, v2))
> > 
> > I'll read it but right in the summary it states precisely one constraint
> > that allows such shortcut: a stationary black hole with a presumed "flat
> > background".
> > 
> > As I said, such shortcuts are frequently used in certain contexts. Things
> > like: "gravitational potential" (which doesn't exist in GR), "gravitons"
> > (which don't exist in GR), "falling space" (which doesn't exist in GR),
> > etc. etc.
> 
> <https://en.wikipedia.org/wiki/Dunning–Kruger_effect>
> 
> Apparently you are a hopeless case.
> 
> If you had the first clue about science, you would know that what I referred
> to directly is properly called the _abstract_, not the "summary", of the paper.

Unless the author of the paper decided to lie in his summary, he presumes the
metric is stationary and he is using a background flat metric. These two items
(which are not generic GR setups) are what allows the "falling space" metaphor
to exist. This is not standard GR, it's "GR + certain constraints".

> If you had the first clue about GR, you would know that it one of its key
> concepts is that the laws of physics have to be valid in *any* (sensible)
> coordinate system.  So it is simply wrong to say that “‘falling space’ does
> not exist in GR”. 

"Falling space" does not exist in GR.

> GR does not make any definitive statement except that
> spacetime curvature is equivalent to energy–momentum density.

No, that's not what GR says. What it says is that at every event spacetime curvature
is correlated in a certain precise way to energy-momentum flux at that event. That's it.
It doesn't even say that "spacetime curvature is due to energy-momentum" which is
a very common incorrect statement, even in textbooks.

> All other
> descriptions were derived from the EFEs by people other than Einstein
> (starting with Schwarzschild in 1915/1916).
> 
> And if you had read past the abstract of the paper, you would know that
> Hamilton and Lisle used Gullstrand–Painlevé coordinates (1921/1922) to
> describe the Schwarzschild metric.

Sure, I never claimed otherwise.

> It is in the first paragraph of the
> first section, “Ⅰ. Introduction”.  Also, it already says in the abstract
> that this description *works* for the Kerr–Newman metric of rotating black
> holes, too,

Sure, he states in the summary that the reasoning in the paper is designed to work
with any stationary metric.

> which ought to be the usual case in our universe due to the
> conservation of angular momentum.
> 
> And BTW, Leonard Susskind PhD

He has a PhD? Really?

> is one of several leading physicists who agree
> with that description. 

Sorry, I'm 100% certain he'd agree with me. If I had nothing better to do, I'd go and talk
to him as he is my neighbour across the bay. You are deluded by all that pop-sci metaphoric
talk.

> See also the video I referred to earlier.
> 
> <https://en.wikipedia.org/wiki/Schwarzschild_metric#Alternative_coordinates>

I know all about "alternative coordinates", trust me.

Please stop assuming I'm some sort of idiot. I've been studying math full-time since
1975 and physics since 1987. Chill out. When I say that GR has no concept of "falling
space", it's because GR has no concept of "falling space". Case closed.

--
Jan

Thread

Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-09-29 13:39 -0700
  Re: Freefall reaches light speed at a black hole Hilton Packett <wod@wcotahr.ce> - 2018-09-30 00:06 +0000
    Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-09-29 20:44 -0700
  Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-09-29 21:32 -0700
    Re: Freefall reaches light speed at a black hole Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-09-30 11:13 +0200
      Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-09-30 13:04 -0700
      Re: Freefall reaches light speed at a black hole Tom Roberts <tjroberts137@sbcglobal.net> - 2018-09-30 16:25 -0500
        Re: Freefall reaches light speed at a black hole Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-10-01 04:33 +0200
          Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-09-30 20:00 -0700
            Re: Freefall reaches light speed at a black hole Hilton Packett <wod@wcotahr.ce> - 2018-10-01 22:40 +0000
          Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-01 09:41 -0700
            Re: Freefall reaches light speed at a black hole Hilton Packett <wod@wcotahr.ce> - 2018-10-01 22:32 +0000
              Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-01 15:41 -0700
            Re: Freefall reaches light speed at a black hole Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-10-07 16:47 +0200
              Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-07 10:29 -0700
                Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-07 10:39 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-07 12:24 -0700
                Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-07 18:03 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-07 22:19 -0700
                Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tc> - 2018-10-08 23:14 +0000
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-07 11:44 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-07 12:25 -0700
                Re: Freefall reaches light speed at a black hole Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-10-08 00:19 +0200
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-07 22:32 -0700
                Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tc> - 2018-10-08 23:18 +0000
    Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-01 08:37 -0700
      Re: Freefall reaches light speed at a black hole Tom Roberts <tjroberts137@sbcglobal.net> - 2018-10-01 22:34 -0500
        Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-02 10:34 -0700
          Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-02 13:24 -0700
            Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-02 16:28 -0700
              Re: Freefall reaches light speed at a black hole Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-10-03 03:10 +0200
              Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-02 19:37 -0700
                Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-02 19:58 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-02 20:03 -0700
                Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-02 20:09 -0700
                Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tt> - 2018-10-03 15:30 +0000
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-03 08:32 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-03 09:42 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-03 10:01 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-03 12:29 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-03 13:49 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-03 13:56 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-03 17:13 -0700
                Re: Freefall reaches light speed at a black hole Tom Roberts <tjroberts137@sbcglobal.net> - 2018-10-04 08:50 -0400
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-04 14:08 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-04 15:12 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-04 15:27 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-04 15:56 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-04 19:27 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-03 13:29 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-04 14:23 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-04 15:16 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-04 19:33 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-05 09:35 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-05 10:37 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-05 11:27 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-05 13:24 -0700
                Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tt> - 2018-10-05 18:27 +0000
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-05 10:36 -0700
                Re: Freefall reaches light speed at a black hole JanPB <filmart@gmail.com> - 2018-10-07 22:33 -0700
                Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-08 13:16 -0700
          Re: Freefall reaches light speed at a black hole Tom Roberts <tjroberts137@sbcglobal.net> - 2018-10-04 08:42 -0400
            Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-04 10:40 -0700
  Re: Freefall reaches light speed at a black hole alsor@interia.pl - 2018-10-01 09:10 -0700
  Re: Freefall reaches light speed at a black hole Double-A <double-a3@hush.com> - 2018-10-07 15:38 -0700
    Re: Freefall reaches light speed at a black hole Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-10-08 01:19 +0200
      Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tc> - 2018-10-08 17:28 +0000
    Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-07 18:04 -0700
  Re: Freefall reaches light speed at a black hole Omar Shabsigh <omar.shabsigh@gmail.com> - 2018-10-07 17:54 -0700
    Re: Freefall reaches light speed at a black hole Tom Roberts <tjroberts137@sbcglobal.net> - 2018-10-07 23:52 -0500
      Re: Freefall reaches light speed at a black hole Odd Bodkin <bodkinodd@gmail.com> - 2018-10-08 13:21 +0000
        Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tt> - 2018-10-08 16:34 +0000
          Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-08 09:41 -0700
            Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tt> - 2018-10-08 16:58 +0000
              Re: Freefall reaches light speed at a black hole mitchrae3323@gmail.com - 2018-10-08 12:39 -0700
                Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tc> - 2018-10-08 20:09 +0000
            Re: Freefall reaches light speed at a black hole Paul Gish <uop@uwrwuao.tt> - 2018-10-08 17:00 +0000
    Re: Freefall reaches light speed at a black hole Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-10-08 19:38 +0200
  Re: Freefall reaches light speed at a black hole Omar Shabsigh <omar.shabsigh@gmail.com> - 2018-10-07 18:04 -0700

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