Relativistic Doppler shift
in [Relativity]
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From: Dono. on 28 Jul 2010 00:32 On Jul 27, 9:00 pm, Tony M <marc...(a)gmail.com> wrote: > On Jul 27, 9:58 am, "Dono." <sa...(a)comcast.net> wrote: > > > > > On Jul 26, 12:11 pm, Tony M <marc...(a)gmail.com> wrote: > > > > I was also thinking about the relativistic Doppler shift lately. > > > Two observers A and B are heading towards each other at relative speed > > > c/2. Observer A shoots a laser beam of frequency fA (as measured by A) > > > towards observer B where it is received at frequency fB (as measured > > > by B). What fB does B measure? What should fB be from observer As > > > perspective? Will the two observers agree on the value of fB? > > > The way I see it: > > > From As perspective B is heading towards him at c/2 so fA is Doppler > > > blue-shifted. Bs clock is slower so theres an additional > > > relativistic blue-shift. B should measure fB = fA x 2 x gamma. > > > From Bs perspective A is heading towards him at c/2. As clock is > > > slower so fA first gets a relativistic red-shift then a Doppler blue- > > > shift. B should measure fB = fA x 2 / gamma. > > > So A and B would disagree on the value of fB, if Im analyzing the > > > problem right. > > > fB/fA=fA/fB=sqrt[(1+v/c)/(1-v/c)] > > > In your case v=c/2 so > > > fB/fA=fA/fB=sqrt(3) > > Dono, > > Math-wise fB/fA=fA/fB only holds when fA=fB. You don't understand the effect
From: BURT on 28 Jul 2010 00:39 The turn of the Earth drives up light's energy at point of absorption by an always blue gamma shift. Mitch Raemsch
From: eric gisse on 28 Jul 2010 01:51 Tony M wrote: > On Jul 27, 9:58 am, "Dono." <sa...(a)comcast.net> wrote: >> On Jul 26, 12:11 pm, Tony M <marc...(a)gmail.com> wrote: >> >> > I was also thinking about the relativistic Doppler shift lately. >> > Two observers A and B are heading towards each other at relative speed >> > c/2. Observer A shoots a laser beam of frequency fA (as measured by A) >> > towards observer B where it is received at frequency fB (as measured >> > by B). What fB does B measure? What should fB be from observer A?s >> > perspective? Will the two observers agree on the value of fB? >> > The way I see it: >> > From A?s perspective B is heading towards him at c/2 so fA is Doppler >> > blue-shifted. B?s clock is slower so there?s an additional >> > relativistic blue-shift. B should measure fB = fA x 2 x gamma. >> > From B?s perspective A is heading towards him at c/2. A?s clock is >> > slower so fA first gets a relativistic red-shift then a Doppler blue- >> > shift. B should measure fB = fA x 2 / gamma. >> > So A and B would disagree on the value of fB, if I?m analyzing the >> > problem right. >> >> fB/fA=fA/fB=sqrt[(1+v/c)/(1-v/c)] >> >> In your case v=c/2 so >> >> fB/fA=fA/fB=sqrt(3) > > Dono, > > Math-wise fB/fA=fA/fB only holds when fA=fB. > fB/fA=sqrt(3) means fB>fA > fA/fB=sqrt(3) means fA>fB > They can't both be true. Please stop frame jumping.
From: Koobee Wublee on 28 Jul 2010 02:20 On Jul 25, 6:48 am, "Dono." <sa...(a)comcast.net> wrote: > On Jul 24, 11:03 pm, "I.N. Galidakis" wrote: > > I know the Doppler shift expression for relative motion, I just don't know > > whether to put v=omega*r in this case, or that, multiplied by some cosine or > > sine, since the velocity of the wave emitter and the linear velocity from > > rotation are perpendicular when the beam hits the observer. > > You only get transverse Doppler effect, so you need to put v=omega*r, > no cosine, in the formula for transverse Doppler effect. Precisely: > > f_observed=f_emitted*sqrt(1-(omega*r/c)^2)- Hide quoted text - Dono, the one who does not know anything, needs to be advised that according the equation describing energy, the transverse Doppler effect under SR is exactly the opposite of what you wrote. See below. E' = E / sqrt(1 - v^2 / c^2) h f' = h f / sqrt(1 - v^2 / c^2) f_observed = f_emitted / sqrt(1 - v^2 / c^2) Once again, SR (as well as GR) is able to predict anything possible (ie: anything you can imagine). Some would say the ability for SR and GR to predict any phenomena possible, even if they are contradictory to each, is the greatest achievements of relativity. However, true scholars of physicists would know better. They would call that completely bullshit. <shrug>
From: Dono. on 28 Jul 2010 09:18
On Jul 27, 11:20 pm, Koobee Wublee <koobee.wub...(a)gmail.com> wrote: >snip cretinisms< Imbecile : http://en.wikipedia.org/wiki/Relativistic_Doppler_effect#Transverse_Doppler_effect |