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Groups > sci.physics.relativity > #398624
| From | Melzzzzz <mel@zzzzz.com> |
|---|---|
| Newsgroups | sci.physics.relativity |
| Subject | Re: This is your guru |
| Date | 2016-11-16 19:28 +0100 |
| Organization | albasani.net |
| Message-ID | <20161116192839.56edf49b@maxa-pc> (permalink) |
| References | <e1398e7a-da47-4ca1-b07a-b2927fd989a9@googlegroups.com> <20161116105207.31ebbe9f@maxa-pc> <MLCdnVCpc9VZFbHFnZ2dnUU7_8zNnZ2d@giganews.com> |
On Wed, 16 Nov 2016 10:26:43 -0600
Tom Roberts <tjroberts137@sbcglobal.net> wrote:
> On 11/16/16 11/16/16 - 3:52 AM, Melzzzzz wrote:
> > Well, following formula from wikipedia:
> > ds^2 = Edx^2 + 2Fdxdy+Gdy^2
> > E = 1/x^4, F = 0 , G = 1
> > and transformation tensor is:
> > E F
> > F G
> >
> > so metric tensor is:
> > 1/x^4 0
> > 0 1
>
> Actually not. That is the COMPONENTS of the metric tensor projected
> onto the coordinates {x,y}.
>
> Note there is a nomenclature ambiguity here: ds^2 could be the metric
> tensor, or it could be the line element -- both meanings are used,
> but in an ASCII newsgroup they are indistinguishable. (In either case
> one can directly read the components of the metric for these
> coordinates.)
>
> If ds^2 is the metric tensor, then ds^2, dx, and dy should be printed
> in bold text, and the tensor-product symbol X has been omitted by
> convention; using more standard nomenclature, the equation is
> implicitly understood to be: ds^2 = E dx X dx + 2 F dx X dy + G dy X
> dy [ds^2,dx,dy bold] Here dx and dy are the usual 1-forms, and
> ds^2 is explicitly a symmetric rank-2 tensor (with a funny symbol --
> feel free to replace ds^2 with g).
>
> If, on the other hand, ds^2 is the line element, then there is no
> nomenclature convention, no bold text, no tensor-product symbols, and
> ds, dx, and dy are all ordinary differentials along some
> (unspecified) path of integration.
>
> In only the second case is ds^2 the square of some quantity.
>
> > Well strictly speaking, formula is not complete without
> > explanation.
>
> YES! All too many people around here forget this important point,
> presenting meaningless formulas without explanations. Your
> recognition of this is why I provided the above explanation.
>
>
> JanPB knows all this, but you other guys apparently do not. Of course
> none of you have actually answered his challenge question. (I can do
> so, and he knows I can, but why should I spoil the circus....)
>
> Tom Roberts
What was challenge question? ;)
I just read about metric tensor and this ;)
I can't probably answer as I am not physician. I am programmer with
some mathematical background...
I can somewhat understand physics but too rusty, too many years of
coding and not doing math actually ...
--
press any key to continue or any other to quit
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This is your guru mlwozniak@wp.pl - 2016-11-16 00:09 -0800
Re: This is your guru Melzzzzz <mel@zzzzz.com> - 2016-11-16 10:52 +0100
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 02:41 -0800
Re: This is your guru Melzzzzz <mel@zzzzz.com> - 2016-11-16 11:43 +0100
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 03:49 -0800
Re: This is your guru Melzzzzz <mel@zzzzz.com> - 2016-11-16 13:18 +0100
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 04:48 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-16 21:54 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 23:19 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-16 23:32 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 23:38 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-17 00:14 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-17 00:38 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-17 10:37 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-17 22:36 -0800
Re: This is your guru Tom Roberts <tjroberts137@sbcglobal.net> - 2016-11-16 10:26 -0600
Re: This is your guru Kieth Staudt <KiethS@StaudtInstitute.info> - 2016-11-16 18:12 +0000
Re: This is your guru Melzzzzz <mel@zzzzz.com> - 2016-11-16 19:28 +0100
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-16 21:57 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 23:34 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-17 00:23 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-17 03:37 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-17 10:39 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-17 22:50 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-17 23:52 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-18 00:53 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-18 12:28 -0800
Re: This is your guru Maciej Woźniak <mlwozniak@wp.pl> - 2016-11-19 10:07 +0100
Re: This is your guru Marion Vanriper <Marion@Vanriper.info> - 2016-11-26 09:30 +0000
Re: This is your guru Tom Roberts <tjroberts137@sbcglobal.net> - 2016-11-17 10:09 -0600
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-16 12:11 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 23:14 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-16 23:35 -0800
Re: This is your guru mlwozniak@wp.pl - 2016-11-16 23:52 -0800
Re: This is your guru JanPB <filmart@gmail.com> - 2016-11-17 00:25 -0800
Re: This is your guru paparios <paparios@gmail.com> - 2016-11-17 03:59 -0800
Re: This is your guru "Dan S. MacAbre" <no@way.com> - 2016-11-17 12:12 +0000
Re: This is your guru Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-11-18 05:07 +0100
Re: This is your guru "Dan S. MacAbre" <no@way.com> - 2016-11-18 10:02 +0000
Re: This is your guru Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-11-18 22:13 +0100
Re: This is your guru "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-11-18 21:46 -0800
Re: This is your guru "Paul B. Andersen" <relativity@paulba.no> - 2016-11-19 09:30 +0100
Re: This is your guru Tom Roberts <tjroberts137@sbcglobal.net> - 2016-11-19 10:01 -0600
Re: This is your guru "David (Time Lord) Fuller" <fuller.david@hotmail.com> - 2016-11-19 08:07 -0800
Re: This is your guru Norberto Haman <norberman@norberman.info> - 2016-11-19 16:37 +0000
Re: This is your guru Steven Carlip <carlip@physics.ucdavis.edu> - 2016-11-20 09:37 -0800
Re: This is your guru Norberto Haman <norberman@norberman.info> - 2016-11-20 20:32 +0000
Re: This is your guru Steven Carlip <carlip@physics.ucdavis.edu> - 2016-11-20 15:54 -0800
Re: This is your guru Maryann Tonn <libradaz@libradazert.info> - 2016-11-21 15:00 +0000
Re: This is your guru Steven Carlip <carlip@physics.ucdavis.edu> - 2016-11-21 19:16 -0800
Re: This is your guru Maryann Tonn <libradaz@libradazert.info> - 2016-11-22 10:39 +0000
Re: This is your guru paparios <paparios@gmail.com> - 2016-11-22 03:16 -0800
Re: This is your guru Maryann Tonn <libradaz@libradazert.info> - 2016-11-22 11:24 +0000
Re: This is your guru Ned Latham <nedlatham@woden.valhalla.oz> - 2016-11-22 12:13 +0000
Re: This is your guru benj <benj@nobody.net> - 2016-11-22 17:37 -0500
Re: This is your guru Steven Carlip <carlip@physics.ucdavis.edu> - 2016-11-22 22:57 -0800
Re: This is your guru Dusty Kollman <uberdriver@uberdriver.info> - 2016-11-23 13:37 +0000
Re: This is your guru paparios <paparios@gmail.com> - 2016-11-23 06:04 -0800
Re: This is your guru Dusty Kollman <uberdriver@uberdriver.info> - 2016-11-23 14:27 +0000
Re: This is your guru paparios <paparios@gmail.com> - 2016-11-23 06:44 -0800
Re: This is your guru Dusty Kollman <uberdriver@uberdriver.info> - 2016-11-23 14:56 +0000
Re: This is your guru Steven Carlip <carlip@physics.ucdavis.edu> - 2016-11-23 10:46 -0800
Re: This is your guru Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-11-23 23:21 +0100
Re: This is your guru Bob Goodman <bobg@boobgodman.info> - 2016-11-23 22:58 +0000
Re: This is your guru Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-11-25 20:00 +0100
Re: This is your guru Bernardo Dearmond <bnard@dearmond.org> - 2016-11-25 21:46 +0000
Re: This is your guru Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-11-25 22:56 +0100
Re: This is your guru "David (Lord Kronos) Fuller" <fuller.david@hotmail.com> - 2016-11-23 20:13 -0800
Re: This is your guru Odd Bodkin <bodkinodd@gmail.com> - 2016-11-23 09:24 -0600
Re: This is your guru Dusty Kollman <uberdriver@uberdriver.info> - 2016-11-23 15:33 +0000
Re: This is your guru Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-11-23 23:23 +0100
Re: This is your guru "David (Lord Kronos) Fuller" <fuller.david@hotmail.com> - 2016-11-23 20:15 -0800
Re: This is your guru Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-11-25 20:05 +0100
Re: This is your guru "David (Lord Kronos) Fuller" <fuller.david@hotmail.com> - 2016-11-25 14:57 -0800
Re: This is your guru Dusty Kollman <uberdriver@uberdriver.info> - 2016-11-23 18:28 +0000
Re: This is your guru Poutnik <poutnik4nntp@gmail.com> - 2016-11-23 19:37 +0100
Re: This is your guru Dusty Kollman <uberdriver@uberdriver.info> - 2016-11-23 18:39 +0000
Re: This is your guru "David (Lord Kronos) Fuller" <fuller.david@hotmail.com> - 2016-11-21 22:40 -0800
Re: This is your guru Tom Roberts <tjroberts137@sbcglobal.net> - 2016-11-19 10:47 -0600
Re: This is your guru Norberto Haman <norberman@norberman.info> - 2016-11-19 17:20 +0000
Re: This is your guru mlwozniak@wp.pl - 2016-11-17 04:37 -0800
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