An Embarrassing Question for Relativists
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From: Inertial on 31 Oct 2009 03:30 "Henry Wilson DSc." <HW@..> wrote in message news:hoone51u6noqvbupeht8hpt2eklla6ta76(a)4ax.com... > On Sat, 31 Oct 2009 12:01:09 +1100, "Inertial" <relatively(a)rest.com> > wrote: > >>"Henry Wilson DSc." <HW@..> wrote in message >>news:n3kme5d88tqs5fucd6nia6rr5ckkhjpuoh(a)4ax.com... >>> On Fri, 30 Oct 2009 07:24:50 -0700 (PDT), rotchm <rotchm(a)gmail.com> >>> wrote: >>> >>>> >>>>> Look at the diagram I drew in the original message. YOU are the third >>>>> observer. >>>>> >>>>> The light from S1 approaches O2 at c-v. >>>> >>>>No it does not. Or, perhaps it does. I depends on what *you* mean. >>>>Your sentence is ambiguous and has different interpretations. Make it >>>>more clear: specify who is the observer ( specify relative to which >>>>frame). >>>> >>>>> The light from S2 approaches O2 at c. >>>> >>>>This sentence is a little more clear since it has basically has only >>>>one possible interpretation. >>>> >>>> >>>>> How by any stretch of the imagination can anyone claim that the two >>>>> rays >>>>> are >>>>> traveling at the same speed? >>>> >>>>They are: >>>> >>>>Wrt O1, *the* ray(s) are approaching O1 with speed c, no? >>>>Wrt O2, *the* ray(s) are approaching O2 with speed c, no? >>>> >>>> >>>>Now... >>>> >>>>Wrt O1, the *closing speed* between (the ray and O2) is c-v. >>>> >>>>Understand the difference? >>>> >>>>We are not talking about the *speed* of a ray. We are talking about >>>>*closing speed*, a totally different concept ( which has nothing to do >>>>with SR by the way). >>>> >>>>We are not talking about the speed of *a ray*. We are talking about a >>>>difference of speeds of *two* objects. >>> >>> That doesn't alter the fact that if a particular observer sees two rays >>> closing >>> on a particular observer at different speeds those rays cannot possibly >>> be >>> traveling at the same speed. >> >>But he doesn't > > If a source is at rest wrt an observer, its light MUST close on that > observer > at c. If you mean the speed relative to the observer is c, then of course that is true, regardless of the speed of the source If you mean the closing speed as measured by some other non-co-moving observer, then it will not be c > Any claim that it doesn't is bogus. You're the only one that was claiming otherwise. You going back on your position now?
From: Inertial on 31 Oct 2009 03:34 "Henry Wilson DSc." <HW@..> wrote in message news:cjpne55bmunjpd8tqbp4fdg2b0783hretu(a)4ax.com... > On Fri, 30 Oct 2009 14:34:04 -0700 (PDT), PD <thedraperfamily(a)gmail.com> > wrote: > >>On Oct 30, 4:29 pm, HW@..(Henry Wilson DSc). wrote: >>> On Fri, 30 Oct 2009 06:32:35 -0700 (PDT), PD <thedraperfam...(a)gmail.com> >>> wrote: >>> >On Oct 29, 9:18 pm, HW@..(Henry Wilson DSc). wrote: >>> >> On Thu, 29 Oct 2009 12:02:58 -0700 (PDT), PD >>> >> <thedraperfam...(a)gmail.com> wrote: >>> >> >On Oct 28, 3:38 pm, HW@..(Henry Wilson DSc). wrote: >>> >> >> Consider two light sources and two observers as shown below. S1 is >>> >> >> connected to >>> >> >> O1 and S2 is connected to O2. O2 is moving at v relative to O1. >>> >>> >> >> O1----------------------------------------------------S1 >>> >> >> v<- O2---------------------------------------S2 >>> >>> >> >> According to SR, >>> >>> >> >> light from S1 moves at c towards O1. >>> >>> >> >> Light from S2 moves at c towards O2. >>> >> >> In other words, the CLOSING SPEED of light from S2 on O2 is c. >>> >>> >> >Not in this frame. The CLOSING SPEED of light from S2 on O2 is c-v. >>> >> >However, in the frame where S2 and O2 are at rest and S1 and O1 are >>> >> >moving, then the closing speed of S2 on O2 is c. >>> >>> >> This is an interesting new slant. We now have a disagreement between >>> >> the >>> >> members of the relativist fraternity. >>> >>> >Really? Who's the other? >>> >>> >> My question has split them into two camps. >>> >>> >> >> However the CLOSING SPEED of light from S1 on O2 is c-v. >>> >>> >> >> So we have a situation in which two separate rays of light CLOSE >>> >> >> ON O2 at >>> >> >> different speeds. How can that happen? >>> >>> >> >Well, it helps to know what the words mean. Otherwise you confuse >>> >> >yourself. >>> >>> >> I know what 'closing speed' means. >>> >>> >If you did, you wouldn't have made such a simple goof. >>> >>> >> ...and if two rays have different closing speeds on the same object >>> >> as >>> >> determined by the same observer, then it is bloody obvious they don't >>> >> have the >>> >> same speed at all. >>> >>> >And where is that the case? >>> >>> You claim that the closing speed of S2 on O2 is not c is the type of >>> fairytale >>> one would expect to hear in a madhouse or a mosque....or, of course, in >>> the >>> home of an aetherist.. >> >>Nonsense. In the frame drawn, light is traveling from right to left at >>c. In the frame drawn, O2 is traveling from right to left at v. >>By *definition* of closing speed (you perhaps should look it up), it >>is c-v. >> >>Closing speed is DEFINED as the numerical difference between the >>speeds of two objects, as seen by an observer that is neither of those >>objects. It doesn't HAVE to be neither of those objects In the case where it is one of the objects (or co=moving with one of them) than the closing speed degenerates to relative speed. > Funny! that sounds just like Netonian definition of speed. No .. its nothing like the Newtonian definition of speed. One wouldn't define speed as the difference in speeds. You're such an imbecile Henry .. is there anything you can get right?
From: Androcles on 31 Oct 2009 03:46 "Henry Wilson DSc ." <HW@..> wrote in message news:cjpne55bmunjpd8tqbp4fdg2b0783hretu(a)4ax.com... > On Fri, 30 Oct 2009 14:34:04 -0700 (PDT), PD <thedraperfamily(a)gmail.com> > wrote: > >>On Oct 30, 4:29 pm, HW@..(Henry Wilson DSc). wrote: >>> On Fri, 30 Oct 2009 06:32:35 -0700 (PDT), PD <thedraperfam...(a)gmail.com> >>> wrote: >>> >On Oct 29, 9:18 pm, HW@..(Henry Wilson DSc). wrote: >>> >> On Thu, 29 Oct 2009 12:02:58 -0700 (PDT), PD >>> >> <thedraperfam...(a)gmail.com> wrote: >>> >> >On Oct 28, 3:38 pm, HW@..(Henry Wilson DSc). wrote: >>> >> >> Consider two light sources and two observers as shown below. S1 is >>> >> >> connected to >>> >> >> O1 and S2 is connected to O2. O2 is moving at v relative to O1. >>> >>> >> >> O1----------------------------------------------------S1 >>> >> >> v<- O2---------------------------------------S2 >>> >>> >> >> According to SR, >>> >>> >> >> light from S1 moves at c towards O1. >>> >>> >> >> Light from S2 moves at c towards O2. >>> >> >> In other words, the CLOSING SPEED of light from S2 on O2 is c. >>> >>> >> >Not in this frame. The CLOSING SPEED of light from S2 on O2 is c-v. >>> >> >However, in the frame where S2 and O2 are at rest and S1 and O1 are >>> >> >moving, then the closing speed of S2 on O2 is c. >>> >>> >> This is an interesting new slant. We now have a disagreement between >>> >> the >>> >> members of the relativist fraternity. >>> >>> >Really? Who's the other? >>> >>> >> My question has split them into two camps. >>> >>> >> >> However the CLOSING SPEED of light from S1 on O2 is c-v. >>> >>> >> >> So we have a situation in which two separate rays of light CLOSE >>> >> >> ON O2 at >>> >> >> different speeds. How can that happen? >>> >>> >> >Well, it helps to know what the words mean. Otherwise you confuse >>> >> >yourself. >>> >>> >> I know what 'closing speed' means. >>> >>> >If you did, you wouldn't have made such a simple goof. >>> >>> >> ...and if two rays have different closing speeds on the same object >>> >> as >>> >> determined by the same observer, then it is bloody obvious they don't >>> >> have the >>> >> same speed at all. >>> >>> >And where is that the case? >>> >>> You claim that the closing speed of S2 on O2 is not c is the type of >>> fairytale >>> one would expect to hear in a madhouse or a mosque....or, of course, in >>> the >>> home of an aetherist.. >> >>Nonsense. In the frame drawn, light is traveling from right to left at >>c. In the frame drawn, O2 is traveling from right to left at v. >>By *definition* of closing speed (you perhaps should look it up), it >>is c-v. >> >>Closing speed is DEFINED as the numerical difference between the >>speeds of two objects, as seen by an observer that is neither of those >>objects. > > Funny! that sounds just like Netonian definition of speed. DO NOT FEED THE TROLLS.
From: rotchm on 31 Oct 2009 10:38 > That doesn't alter the fact that if a particular observer sees two rays closing > on a particular observer at different speeds those rays cannot possibly be > traveling at the same speed. SR says that an observer will memasure the speed of light to be c relative to HIMSELF, not "relative to" someone else.
From: rotchm on 31 Oct 2009 10:44
> If a source is at rest wrt an observer, its light MUST close on that observer > at c. > Any claim that it doesn't is bogus. Thats not what SR says. You are confused about what SR says. If a source is at rest wrt an observer, its light MUST close on that observer at c, AS MEASURED BY THAT SAME OBSERVER. And moreover, "closing speed" is different from "speed". You cannot replace "speed" by "cosing speed" in SR. Dont mixup the meaning of words... |