Article View: sci.physics
Article #16172Re: Why does light bend under gravity?
From: critico
Date: Thu, 27 Mar 2008 18:33
Date: Thu, 27 Mar 2008 18:33
78 lines
5702 bytes
5702 bytes
On 16 mar, 20:22, BradGuth <bradg...@gmail.com> wrote: > On Mar 11, 11:21 pm, Pentcho Valev <pva...@yahoo.com> wrote: > > > > > > > On Mar 11, 5:27 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote in > > sci.physics: > > > > Tom wrote: > > > > The speed of light varies depending on the strength of the > > > > gravitational field. Einstein said that. > > > > He said that in 1911, early on the then-unfinished journey to General > > > Relativity. GR itself does not really have this property -- the _LOCAL_ > > > speed of light is everywhere c. When measured over non-local paths the > > > speed of light can vary, but there is no definite dependence on > > > "strength of the gravitational field", it's rather that one must compute > > > an integral over the path to obtain the theoretical value for such a > > > speed measurement. > > > > Yes, as one prolific idiot around here is fixated on, > > > in the APPROXIMATION of weak fields and restriction to > > > paths at fixed gravitational potential, for Newtonian > > > coordinates one can express the non-local COORDINATE > > > speed of light in terms of the gravitational potential. > > > In 1911 Einstein did not understand all the caveats > > > mentioned here, but certainly did by 1915; this idiot > > > still does not understand them. > > > The year is 1920 Roberts Roberts and Divine Albert still believes that > > the speed of light "varies with position" in a gravitational field, as > > Superior Brother Steve Carlip explains to you: > > >http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_o... > > Superior Brother Steve Carlip: "Einstein went on to discover a more > > general theory of relativity which explained gravity in terms of > > curved spacetime, and he talked about the speed of light changing in > > this new theory. In the 1920 book "Relativity: the special andgeneral theory" he wrote: ". . . according to the general theory of > > > relativity, the law of the constancy of the velocity of light in > > vacuo, which constitutes one of the two fundamental assumptions in the > > special theory of relativity [. . .] cannot claim any unlimited > > validity. A curvature of rays of light can only take place when the > > velocity of propagation of light varies with position." Since > > Einstein talks of velocity (a vector quantity: speed with direction) > > rather than speed alone, it is not clear that he meant the speed will > > change, but the reference to special relativity suggests that he did > > mean so. THIS INTERPRETATION IS PERFECTLY VALID AND MAKES GOOD > > PHYSICAL SENSE, but a more modern interpretation is that the speed of > > light is constant in general relativity." > > > In a sense, Superior Brother Steve Carlip is less dishonest (or more > > naive) than you Roberts Roberts. > > > Pentcho Valev > > pva...@yahoo.com > > Interesting, but why does light reflect off a mirror, or get refracted > by an atmosphere? > > Perhaps photons do not actually bend, but merely interact with other > matter, be it regular or dark matter. > . - Brad Guth- Bravo les artistes ! 57 interventions et pas un mot en Français . On est bien sur un groupe fr. n'est-ce pas ? Alors, pour ceux qui ne maîtrisent pas l'englich, il est très difficile de repérer les conneries, car il doit y en avoir un tas , of course... Sans rancune, mais avec un pointe d'mamertume.
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X-Google-Thread: 10b271,1ea0cb1d54d3d906 X-Google-Thread: 10f545,2d47498f99950055 X-Google-Thread: f6c41,2d47498f99950055 X-Google-Thread: fa4c1,c0039b44052ddae9 X-Google-Thread: f74ae,c0039b44052ddae9 X-Google-Attributes: gid10b271,gid10f545,gidf6c41,gidfa4c1,gidf74ae,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII Path: arc1-ca.pugleaf.net!g2news1.google.com!postnews.google.com!c19g2000prf.googlegroups.com!not-for-mail From: critico <pierre.rios@numericable.fr> Newsgroups: sci.physics,sci.physics.relativity,sci.physics.particle,fr.sci.physique,sci.astro Subject: Re: Why does light bend under gravity? Date: Thu, 27 Mar 2008 11:33:15 -0700 (PDT) Organization: http://groups.google.com Lines: 79 Message-ID: <7e32a26f-6003-4f2a-bd6d-774de0924689@c19g2000prf.googlegroups.com> References: <1de25376-cbdf-4a88-9c24-635b73e962f0@e60g2000hsh.googlegroups.com> <82fb1770-1633-4e2b-abd2-02b8f5e4ecee@k2g2000hse.googlegroups.com> <YpBwj.12517$J41.7185@newssvr14.news.prodigy.net> <pan.2008.02.25.17.17.58@canonicalscience.com> <47C31602.1030806@guesswhatuia.no> <k887s35r0tqpss2mmaj14d9v70qblsjt3v@4ax.com> <7ad9324e-a185-4be5-8d37-36608dda682a@s37g2000prg.googlegroups.com> <6oe7s3t3ffk34ik95onbdq5i7ho1man8vh@4ax.com> <5d081222-5b36-4e82-b8d7-8900c2acbbc4@d4g2000prg.googlegroups.com> <L_mBj.16850$Ch6.2540@newssvr11.news.prodigy.net> <4a84042b-1718-45a4-82f9-0e2b9fa12240@x41g2000hsb.googlegroups.com> <e128f415-91cd-452f-a0d6-971cf5338c62@i12g2000prf.googlegroups.com> NNTP-Posting-Host: 89.2.174.169 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: posting.google.com 1206642795 8771 127.0.0.1 (27 Mar 2008 18:33:15 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Thu, 27 Mar 2008 18:33:15 +0000 (UTC) Complaints-To: groups-abuse@google.com Injection-Info: c19g2000prf.googlegroups.com; posting-host=89.2.174.169; posting-account=IKRxogoAAADqtdU1-CwvCc78BhG8aX0i User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1),gzip(gfe),gzip(gfe)