Received: by 10.66.81.170 with SMTP id b10mr1883966pay.31.1349712788550; Mon, 08 Oct 2012 09:13:08 -0700 (PDT) Path: t10ni23656783pbh.0!nntp.google.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Mon, 08 Oct 2012 11:13:08 -0500 Date: Mon, 08 Oct 2012 11:13:07 -0500 From: Tom Roberts User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:15.0) Gecko/20120907 Thunderbird/15.0.1 MIME-Version: 1.0 Newsgroups: sci.physics.relativity Subject: Re: DOPPLER EFFECT (MOVING OBSERVER): VARYING OR CONSTANT WAVELENGTH? References: <6c29317d-cb08-4b67-8db8-02f8e83fdefd@googlegroups.com> <9f8cf742-ca53-4d3e-bb94-143542608d3d@googlegroups.com> In-Reply-To: Message-ID: Lines: 54 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-e3R+b7gnAr4gOX/AW/p6QxGENuwOy9SQFpVjMcUOZ9lwKaqK9GZLCs5pNmCgs9GMM6C664h3xhtyjN8!XpUC0Icl1RbWimX7IcAAkBG70Mnyxo7sWqTteZoQ4dmhh0DrPvRvw1IORoP7qn8I X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3993 X-Original-Bytes: 3932 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 10/7/12 10/7/12 - 8:36 PM, xxein wrote: > An emitter and a receiver in the same FOR maintaining some intrinsic > proper length between them will always cause the same measurement of > light's frequency and wavelength, right? Hmmmm. In what appears to be an overblown attempt to be precise, you have introduced inconsistencies in your description. In particular, to what is this length "intrinsic"? -- Certainly not either the emitter or the receiver. But yes, a receiver at rest in the same INERTIAL FOR as the emitter will always measure the same frequency and wavelength as the emitter. > We can't identify an > absolute rest frame, right? Right. Nobody has ever done so, experimentally. Some people do so in non-scientific situations such as dreams and hallucinations, but that's irrelevant. > So how would that measurement change if > it were an absolute rest frame? This depends on how the "absolute rest frame" is identified, what effects it has, and how one models those effects. As physics currently has no such theory or model, it is not possible to answer such a question. > If it doesn't change then you would > be measuring an intrinsic property of light in the same way a proper > length is intrinsic. Answer my question above, and you'll see you are using the word "intrinsic" improperly. In any case, this would be a property of the EMITTER, not the light. When a given emitter emits a light ray, the phase of the light ray is a function on the manifold. IOW: the events of spacetime where each wavecrest occurs are determined by properties of the emitter. But the spatial distance between any pair of events is NOT an intrinsic property of the pair, it can only be measured by projecting the events onto some length-measuring instrument; the result is determined by both the events involved AND the instrument used (in particular, its motion through the manifold). Ditto for the temporal interval between the pair of events. This is a key concept of physics, common to both relativity and QM: a measurement consists of projecting some physical quantity onto a measuring instrument. This is so for all quantities of interest, such as length, duration, voltage, current, etc. Tom Roberts