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Groups > sci.physics.relativity > #423045 > unrolled thread
| Started by | Pentcho Valev <pvalev@yahoo.com> |
|---|---|
| First post | 2017-06-19 14:30 -0700 |
| Last post | 2017-06-23 11:43 +0000 |
| Articles | 20 on this page of 92 — 19 participants |
Back to article view | Back to sci.physics.relativity
The Secret to Einstein's Twin Paradox Pentcho Valev <pvalev@yahoo.com> - 2017-06-19 14:30 -0700
Re: The Secret to Einstein's Twin Paradox Gary Harnagel <hitlong@yahoo.com> - 2017-06-19 14:48 -0700
Re: The Secret to Einstein's Twin Paradox Eshiki Orakut <usa@iwikuh.ki> - 2017-06-20 13:45 +0000
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-06-20 09:49 -0600
Re: The Secret to Einstein's Twin Paradox Eshiki Orakut <usa@iwikuh.ki> - 2017-06-20 21:10 +0000
Re: The Secret to Einstein's Twin Paradox mlwozniak@wp.pl - 2017-06-21 02:40 -0700
Re: The Secret to Einstein's Twin Paradox JanPB <filmart@gmail.com> - 2017-06-23 04:42 -0700
Re: The Secret to Einstein's Twin Paradox mlwozniak@wp.pl - 2017-06-23 04:48 -0700
Re: The Secret to Einstein's Twin Paradox JanPB <filmart@gmail.com> - 2017-06-23 13:51 -0700
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-22 04:30 -0700
Re: The Secret to Einstein's Twin Paradox JanPB <filmart@gmail.com> - 2017-06-23 04:44 -0700
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-27 07:06 -0700
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-06-27 12:22 -0600
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-06-27 22:44 -0500
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-06-28 07:40 -0600
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-06-29 00:26 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-29 04:01 -0700
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-29 04:14 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-06-29 08:30 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-29 06:54 -0700
Re: The Secret to Einstein's Twin Paradox Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-06-29 14:41 +0200
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-06-29 08:37 -0500
Re: The Secret to Einstein's Twin Paradox Poutnik <poutnik4nntp@gmail.com> - 2017-06-29 16:16 +0200
Re: The Secret to Einstein's Twin Paradox Jim Petroff <ruuri@twjotr.eo> - 2017-06-29 14:29 +0000
Re: The Secret to Einstein's Twin Paradox Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-06-29 16:45 +0200
Re: The Secret to Einstein's Twin Paradox Jim Petroff <ruuri@twjotr.eo> - 2017-06-29 15:00 +0000
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-29 08:11 -0700
Re: The Secret to Einstein's Twin Paradox Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-06-29 17:19 +0200
Re: The Secret to Einstein's Twin Paradox Jim Petroff <ruuri@twjotr.eo> - 2017-06-29 15:34 +0000
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-29 08:39 -0700
Re: The Secret to Einstein's Twin Paradox Jim Petroff <ruuri@twjotr.eo> - 2017-06-29 15:29 +0000
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-01 12:29 -0500
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-07-02 12:35 -0600
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-03 08:18 -0700
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-07-03 09:45 -0600
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-04 05:24 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-03 17:52 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-04 05:45 -0700
Re: The Secret to Einstein's Twin Paradox Poutnik <poutnik4nntp@gmail.com> - 2017-07-04 15:03 +0200
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-07 13:56 -0700
Re: The Secret to Einstein's Twin Paradox Poutnik <poutnik4nntp@gmail.com> - 2017-07-07 23:55 +0200
Re: The Secret to Einstein's Twin Paradox mlwozniak@wp.pl - 2017-07-08 00:15 -0700
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-10 08:43 -0700
Re: The Secret to Einstein's Twin Paradox Upech Bezradne <adeeia@bbzzeop.ic> - 2017-07-08 10:44 +0000
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-10 08:38 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-04 12:56 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-07 13:20 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-08 00:06 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-10 08:26 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-11 10:56 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-11 13:40 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-12 10:13 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-13 10:07 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-14 20:04 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-15 13:49 -0700
Re: The Secret to Einstein's Twin Paradox The Starmaker <starmaker@ix.netcom.com> - 2017-07-15 14:26 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-17 20:20 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-20 07:25 -0700
Re: The Secret to Einstein's Twin Paradox kenseto <setoken@att.net> - 2017-07-05 07:50 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-07-03 18:26 -0500
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-29 07:05 -0700
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-06-29 09:31 -0600
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-28 05:01 -0700
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-06-28 07:52 -0600
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-29 03:47 -0700
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-06-29 10:19 -0600
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-06-30 08:09 -0700
Re: The Secret to Einstein's Twin Paradox Lord Kronos Prime <fuller.david@hotmail.com> - 2017-06-30 08:39 -0700
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-01 08:33 -0700
Re: The Secret to Einstein's Twin Paradox Mike Fontenot <mlfasf@comcast.net> - 2017-06-30 11:30 -0600
Re: The Secret to Einstein's Twin Paradox Jonathan Doolin <good4usoul@gmail.com> - 2017-07-01 08:11 -0700
Re: The Secret to Einstein's Twin Paradox Pentcho Valev <pvalev@yahoo.com> - 2017-06-19 23:58 -0700
Re: The Secret to Einstein's Twin Paradox JanPB <filmart@gmail.com> - 2017-06-20 03:18 -0700
Re: The Secret to Einstein's Twin Paradox Lipek Mniak <iluka@sskwpiw.pp> - 2017-06-23 11:47 +0000
Re: The Secret to Einstein's Twin Paradox The Starmaker <starmaker@ix.netcom.com> - 2017-06-23 11:18 -0700
Re: The Secret to Einstein's Twin Paradox Eckard B <eckard.blumschein@arcor.de> - 2017-06-21 09:21 -0700
Re: The Secret to Einstein's Twin Paradox Poutnik <poutnik4nntp@gmail.com> - 2017-06-21 19:33 +0200
Re: The Secret to Einstein's Twin Paradox Poutnik <poutnik4nntp@gmail.com> - 2017-06-22 07:32 +0200
Re: The Secret to Einstein's Twin Paradox mlwozniak@wp.pl - 2017-06-21 23:16 -0700
Re: The Secret to Einstein's Twin Paradox Lipek Mniak <iluka@sskwpiw.pp> - 2017-06-23 11:33 +0000
Re: The Secret to Einstein's Twin Paradox Eckard B <eckard.blumschein@arcor.de> - 2017-06-22 08:14 -0700
Re: The Secret to Einstein's Twin Paradox Poutnik <poutnik4nntp@gmail.com> - 2017-06-22 18:13 +0200
Re: The Secret to Einstein's Twin Paradox Lipek Mniak <iluka@sskwpiw.pp> - 2017-06-23 11:35 +0000
Re: The Secret to Einstein's Twin Paradox The Starmaker <starmaker@ix.netcom.com> - 2017-06-23 11:15 -0700
Re: The Secret to Einstein's Twin Paradox Tom Roberts <tjroberts137@sbcglobal.net> - 2017-06-22 15:38 -0500
Re: The Secret to Einstein's Twin Paradox Eckard B <eckard.blumschein@arcor.de> - 2017-06-23 03:22 -0700
Re: The Secret to Einstein's Twin Paradox Lipek Mniak <iluka@sskwpiw.pp> - 2017-06-23 11:38 +0000
Re: The Secret to Einstein's Twin Paradox Poutnik <poutnik4nntp@gmail.com> - 2017-06-28 08:32 +0200
Re: The Secret to Einstein's Twin Paradox mlwozniak@wp.pl - 2017-06-23 03:37 -0700
Re: The Secret to Einstein's Twin Paradox bigal95210@gmail.com - 2017-06-21 16:48 -0700
Re: The Secret to Einstein's Twin Paradox John Gogo <jfgogo22@yahoo.com> - 2017-07-14 19:00 -0700
Re: The Secret to Einstein's Twin Paradox Lipek Mniak <iluka@sskwpiw.pp> - 2017-06-23 11:43 +0000
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| From | Poutnik <poutnik4nntp@gmail.com> |
|---|---|
| Date | 2017-07-07 23:55 +0200 |
| Message-ID | <ojovp4$2dm$1@dont-email.me> |
| In reply to | #424205 |
Dne 07/07/2017 v 22:56 Jonathan Doolin napsal(a): > On Tuesday, July 4, 2017 at 8:03:17 AM UTC-5, Poutnik wrote: >> >> You get it wrong. >> Time t' does not belong to the same frame as location x. >> > > But if you can read rulers and clocks from a frame, you can see the clocks and rulers of each frame from any position. > > t' would be a measure of the time of events on clocks comoving with the origin of the primed frame. > t is the measure of time of events on clocks comoving with the origin of the unprimed frame > x is the measure of positions of events by rulers comoving with the origin of the unprimed frame. > x' is the measure of positions of events by rulers comoving with the origin of the primed frame. In system O, you can observe only x and t, a static and a moving clocks within O, a static and a moving ruler within O, In system O', you can observe only x' and t', a static and a moving clocks within O', a static and a moving ruler within O', How would look in O x','t', both O' clocks time and both O' rulers readings, ( and vice versa ), you have to calculate via LT. -- Poutnik ( The Pilgrim, Der Wanderer ) A wise man guards words he says, as they say about him more, than he says about the subject.
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| From | mlwozniak@wp.pl |
|---|---|
| Date | 2017-07-08 00:15 -0700 |
| Message-ID | <c49c5f48-ea26-4b36-8efd-7da0340417c2@googlegroups.com> |
| In reply to | #424211 |
W dniu piątek, 7 lipca 2017 23:55:25 UTC+2 użytkownik Poutnik napisał: > Dne 07/07/2017 v 22:56 Jonathan Doolin napsal(a): > > On Tuesday, July 4, 2017 at 8:03:17 AM UTC-5, Poutnik wrote: > >> > >> You get it wrong. > >> Time t' does not belong to the same frame as location x. > >> > > > > But if you can read rulers and clocks from a frame, you can see the clocks and rulers of each frame from any position. > > > > t' would be a measure of the time of events on clocks comoving with the origin of the primed frame. > > t is the measure of time of events on clocks comoving with the origin of the unprimed frame > > x is the measure of positions of events by rulers comoving with the origin of the unprimed frame. > > x' is the measure of positions of events by rulers comoving with the origin of the primed frame. > > In system O, you can observe only > x and t, > a static and a moving clocks within O, > a static and a moving ruler within O, And walking a street you can observe only trees and lanterns running around. A relativistic moron said! A relativistic moron simply can't be wrong.
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-10 08:43 -0700 |
| Message-ID | <95f0a8bf-6609-401c-8e16-79c31211d000@googlegroups.com> |
| In reply to | #424248 |
On Saturday, July 8, 2017 at 2:15:09 AM UTC-5, mlwo...@wp.pl wrote: > W dniu piątek, 7 lipca 2017 23:55:25 UTC+2 użytkownik Poutnik napisał: > > Dne 07/07/2017 v 22:56 Jonathan Doolin napsal(a): > > > On Tuesday, July 4, 2017 at 8:03:17 AM UTC-5, Poutnik wrote: > > >> > > >> You get it wrong. > > >> Time t' does not belong to the same frame as location x. > > >> > > > > > > But if you can read rulers and clocks from a frame, you can see the clocks and rulers of each frame from any position. > > > > > > t' would be a measure of the time of events on clocks comoving with the origin of the primed frame. > > > t is the measure of time of events on clocks comoving with the origin of the unprimed frame > > > x is the measure of positions of events by rulers comoving with the origin of the unprimed frame. > > > x' is the measure of positions of events by rulers comoving with the origin of the primed frame. > > > > In system O, you can observe only > > x and t, > > a static and a moving clocks within O, > > a static and a moving ruler within O, > > And walking a street you can observe only > trees and lanterns running around. > A relativistic moron said! A relativistic > moron simply can't be wrong. Day after day alone on the hill The man with the foolish grin Is keeping perfectly still But nobody wants to know him They can see that he's just a fool And he never seem to notice But the fool on the hill Sees the sun going down And the eyes in his head See the world spinning round Well on the way, his head in a cloud The man of a thousand voices Is talking perfectly loud But nobody ever hears him Or the sound he appears to make And he never seems to notice But the fool on the hill Sees the sun going down And the eyes in his head See the world spinning round Oh, round, round, round, round, round And nobody seems to like him They can tell what he wants to do And he never shows his feelings But the fool on the hill Sees the sun going down And the eyes in his head See the world spinning round Oh, round, round, round, round, round And he never listen to them He knows that they're the fools But they don't like him The fool on the hill Sees the sun going down And the eyes in his head See the world spinning round Oh, round, round, round, round, round Oh Songwriters: John Lennon / Paul McCartney The Fool on the Hill lyrics © Sony/ATV Music Publishing LLC
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| From | Upech Bezradne <adeeia@bbzzeop.ic> |
|---|---|
| Date | 2017-07-08 10:44 +0000 |
| Message-ID | <ojqd35$1it1$2@gioia.aioe.org> |
| In reply to | #424211 |
Poutnik wrote: > In system O, you can observe only x and t, > a static and a moving clocks within O, a static and a moving ruler > within O, > In system O', you can observe only x' and t', > a static and a moving clocks within O', > a static and a moving ruler within O', > How would look in O x','t', > both O' clocks time and both O' rulers readings, ( and vice versa ), > you have to calculate via LT. Totally nonsense. You still didn't learn what the SR is standing for. Sit down.
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-10 08:38 -0700 |
| Message-ID | <40eab03e-dd00-4df7-8226-ce50dbc7309e@googlegroups.com> |
| In reply to | #424211 |
On Friday, July 7, 2017 at 4:55:25 PM UTC-5, Poutnik wrote: > Dne 07/07/2017 v 22:56 Jonathan Doolin napsal(a): > > On Tuesday, July 4, 2017 at 8:03:17 AM UTC-5, Poutnik wrote: > >> > >> You get it wrong. > >> Time t' does not belong to the same frame as location x. > >> > > > > But if you can read rulers and clocks from a frame, you can see the clocks and rulers of each frame from any position. > > > > t' would be a measure of the time of events on clocks comoving with the origin of the primed frame. > > t is the measure of time of events on clocks comoving with the origin of the unprimed frame > > x is the measure of positions of events by rulers comoving with the origin of the unprimed frame. > > x' is the measure of positions of events by rulers comoving with the origin of the primed frame. > > In system O, you can observe only > x and t, > a static and a moving clocks within O, > a static and a moving ruler within O, > > In system O', you can observe only > x' and t', > a static and a moving clocks within O', > a static and a moving ruler within O', > > How would look in O > x','t', > both O' clocks time and both O' rulers readings, > ( and vice versa ), > you have to calculate via LT. > > how x' would look in O. is as rulers in motion. http://www.spoonfedrelativity.com/pages/PenroseTerrellRotation.php And how t' would look in O is as readings of clocks on clock-faces in motion.
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| From | Tom Roberts <tjroberts137@sbcglobal.net> |
|---|---|
| Date | 2017-07-04 12:56 -0500 |
| Message-ID | <3MWdnWY2hdBYS8bEnZ2dnUU7_83NnZ2d@giganews.com> |
| In reply to | #423925 |
On 7/4/17 7/4/17 7:45 AM, Jonathan Doolin wrote: > On Monday, July 3, 2017 at 5:52:14 PM UTC-5, tjrob137 wrote: >> On 7/3/17 7/3/17 10:18 AM, Jonathan Doolin wrote: >>> On Sunday, July 2, 2017 at 1:35:04 PM UTC-5, Mike_Fontenot wrote: >>>> On 7/1/17 11:29 AM, Tom Roberts wrote: >>>>> But as long as the observer keeps track of his speed relative to the >>>>> original inertial frame [#], then from the value of his own watch he can >>>>> continuously keep track of the time coordinate of the inertial frame (by >>>>> inverting the equation for "time dilation" relative to an inertial >>>>> frame). >>> I think it is confusing here, Tom, that you refer to "the time coordinate of >>> the inertial frame". I think, below, Mike guessed that you mean "the time >>> coordinate of the inertial frame AT the position of the traveling twin." >> >> But the value of the time coordinate of an inertial frame is independent of >> location -- it has the same value everywhere, because that's what those words >> mean (when applied to an inertial frame, which is one of the main reason >> inertial frames are so useful). So your addition adds nothing. > > I'm not sure what scenario you're thinking of, I described it earlier in this thread, and much of it is quoted above -- go back and read. > But it's certainly not generally true. Yes, it most definitely _IS_ generally true that "the value of the time coordinate of an inertial frame is independent of location". Because that is what these words mean, as I said. > Recall the Lorentz Transformation for t': > t' = (t - vx/c^2)/sqrt(1-v^2/c^2) > Here, you can see that the time, t', is NOT > independent of location, x. You do not understand what the Lorentz transform MEANS. Here's what it means: Given two inertial frames S and S', with relative velocity v and the usual construction of coordinates in both frames, then an event with coordinate (x,t) in S will have coordinates (x',t') in S'. That has nothing whatsoever to do with the FACT that at time t=T in S, the time coordinate of S has value T everywhere in S, independent of location. This last is what "the value of the time coordinate of an inertial frame is independent of location" means. > Sure, but he would also understand > that the time coordinate of the home twin's frame > would not be the same at his own position, > and at the home twin's position. That is just not true, because I stipulated he use the home twin's inertial frame. You need to learn what an inertial frame actually is. Tom Roberts
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-07 13:20 -0700 |
| Message-ID | <6bb96802-84b2-4a01-b7d4-4338e8739e8c@googlegroups.com> |
| In reply to | #423941 |
On Tuesday, July 4, 2017 at 12:56:29 PM UTC-5, tjrob137 wrote: > > That is just not true, because I stipulated he use the home twin's inertial > frame. You need to learn what an inertial frame actually is. > That's absurd, of course. You don't get to stipulate that the traveling twin "uses" the home twin's inertial frame. He can only observe reality from his own point-of-view.
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| From | Tom Roberts <tjroberts137@sbcglobal.net> |
|---|---|
| Date | 2017-07-08 00:06 -0500 |
| Message-ID | <8ZmdnQnWUNTX9f3EnZ2dnUU7_83NnZ2d@giganews.com> |
| In reply to | #424202 |
On 7/7/17 7/7/17 3:20 PM, Jonathan Doolin wrote: > On Tuesday, July 4, 2017 at 12:56:29 PM UTC-5, tjrob137 wrote: >> That is just not true, because I stipulated he use the home twin's inertial >> frame. You need to learn what an inertial frame actually is. > > That's absurd, of course. > You don't get to stipulate that the traveling twin "uses" the home twin's > inertial frame. What is absurd is your disconnect from what I actually said in a previous post: (... traveler is continuously keeping track of the time coordinate of the home twin's inertial frame...) What I suggested answers this rather obvious question: if [the traveler were] to immediately stop in [the home twin's] inertial frame, right here and now, how old would [the home twin] be? For that I do get to stipulate which frame the traveler stops in, and the only one that answers the question "how old is the home twin?" is the home twin's inertial frame. > He can only observe reality from his own point-of-view. Sure. And _IF_ the traveler IMMEDIATELY STOPPED in the home twin's inertial frame, and knew what the time coordinate of that frame was at the instant of stopping, then the traveler would know the age of the home twin SIMULTANEOUSLY IN THEIR NOW COMMON INERTIAL FRAME. I probably won't continue here, and certainly won't continue to debate what people said earlier in the thread. Tom Roberts
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-10 08:26 -0700 |
| Message-ID | <23ea32ef-d5af-40ab-bec9-7a1462261819@googlegroups.com> |
| In reply to | #424230 |
On Saturday, July 8, 2017 at 12:06:25 AM UTC-5, tjrob137 wrote: > On 7/7/17 7/7/17 3:20 PM, Jonathan Doolin wrote: > > On Tuesday, July 4, 2017 at 12:56:29 PM UTC-5, tjrob137 wrote: > >> That is just not true, because I stipulated he use the home twin's inertial > >> frame. You need to learn what an inertial frame actually is. > > > > That's absurd, of course. > > You don't get to stipulate that the traveling twin "uses" the home twin's > > inertial frame. > > What is absurd is your disconnect from what I actually said in a previous post: > > (... traveler is continuously keeping track of the time > coordinate of the home twin's inertial frame...) > > What I suggested answers this rather obvious question: if [the > traveler were] to immediately stop in [the home twin's] inertial > frame, right here and now, how old would [the home twin] be? > > For that I do get to stipulate which frame the traveler stops in, and the only > one that answers the question "how old is the home twin?" is the home twin's > inertial frame. > > > He can only observe reality from his own point-of-view. > > Sure. And _IF_ the traveler IMMEDIATELY STOPPED in the home twin's inertial > frame, and knew what the time coordinate of that frame was at the instant of > stopping, then the traveler would know the age of the home twin SIMULTANEOUSLY > IN THEIR NOW COMMON INERTIAL FRAME. > > I probably won't continue here, and certainly won't continue > to debate what people said earlier in the thread. > > Tom Roberts You're free, of course, to debate or not debate me but I'd like to question you, though about the nature of this immediate stopping that you are stipulating. First of all, do you think your authority to stipulate immediate stopping renders either me or Mike Fontenot wrong about the nature of Current Age of Distant Objects? Because it seems like you're thinking because you can define "now" according to the isoclines of time of the home-twin, that we cannot just as easily define "now" according to the isoclines of time of the traveling twin. You seem to regard the home-twin's isoclines of simultaneity as "correct" and the traveling twin's isoclines of simultaneity as "incorrect". And so to get this "correct" idea of simultaneity, you stipulate that the traveling twin must be "immediately stopped in the home twin's inertial frame" But exactly how you envision this "stopping", within the context of the thought experiment? Are you picturing something like an "instantaneous stop"? Where the traveling twin is going on his way, but stops for zero time, and then accelerates again to his original trajectory? The trouble with this is that zero-time is not the way velocity works. You can't have an instantaneous zero velocity, dx/dt, when you have dt=0. Or are you thinking in terms of changing the nature of the thought experiment? Are you stipulating that the traveling twins are locked up so that they cannot make any observations unless he is stopped relative to the home twin? Or did you have some other idea in mind when you say the traveling twin must be "immediately stopped"?
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| From | Tom Roberts <tjroberts137@sbcglobal.net> |
|---|---|
| Date | 2017-07-11 10:56 -0500 |
| Message-ID | <nvudnXiyCNCNaPnEnZ2dnUU7_8xi4p2d@giganews.com> |
| In reply to | #424437 |
On 7/10/17 7/10/17 - 10:26 AM, Jonathan Doolin wrote: > do you think your authority to stipulate immediate stopping renders either me > or Mike Fontenot wrong about the nature of Current Age of Distant Objects? I think the CADO frame is a "solution" to a NON-problem. Because the "current age" it gives is not measurable without an OUTRAGEOUSLY impossible set of assistant observers. That requires a co-moving and co-accelerating assistant who passes the home twin at the instant of measurement, and then communicates the answer to the traveling twin -- not really "CURRENT age", but rather "age back when I measured it". Whenever the traveling twin changes acceleration, this requires an entirely new set of distant assistants.... > Because it seems like you're thinking because you can define "now" according > to the isoclines of time of the home-twin, that we cannot just as easily > define "now" according to the isoclines of time of the traveling twin. You can define simultaneity (the meaning of "now") however you like. Basically this is so because over macroscopic distances it simply does not matter -- Nature certainly does not use such notions. So this is just a word game; one that is irrelevant to physics. > You > seem to regard the home-twin's isoclines of simultaneity as "correct" and the > traveling twin's isoclines of simultaneity as "incorrect". No. I just think that what I described is what an astronaut would actually want to know. The "CADO frame" yields ages that do not behave like ages "ought" to behave (monotonically increasing); my approach does. > And so to get this "correct" idea of simultaneity, you stipulate that the > traveling twin must be "immediately stopped in the home twin's inertial > frame" But exactly how you envision this "stopping", within the context of > the thought experiment? The stopping is just as valid as any other part of the gedanken. > Are you picturing something like an "instantaneous stop"? Yes. That's what I said: "immediately stop, right here and now". How long the traveling twin remains stopped is irrelevant. Tom Roberts
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-11 13:40 -0700 |
| Message-ID | <4cfb2b43-2a42-48a4-b076-97c60cc2b110@googlegroups.com> |
| In reply to | #424520 |
On Tuesday, July 11, 2017 at 10:56:07 AM UTC-5, tjrob137 wrote: > On 7/10/17 7/10/17 - 10:26 AM, Jonathan Doolin wrote: > > do you think your authority to stipulate immediate stopping renders either me > > or Mike Fontenot wrong about the nature of Current Age of Distant Objects? > > I think the CADO frame is a "solution" to a NON-problem. Because the "current > age" it gives is not measurable without an OUTRAGEOUSLY impossible set of > assistant observers. > > That requires a co-moving and co-accelerating assistant who > passes the home twin at the instant of measurement, and then > communicates the answer to the traveling twin -- not really > "CURRENT age", but rather "age back when I measured it". > Whenever the traveling twin changes acceleration, this > requires an entirely new set of distant assistants.... > I agree that distant co-accelerating observers are impossible. The twin paradox scenario does not require the existence of co-moving assistants for either the stay-at-home twin, or the traveling twin. And in the same sense that "distant now" is well defined at any given moment for the stay-at-home twin, distant now is also well defined at any given moment for the traveling twin. One could set up distributions of inertial observers moving at many different velocities, and then at any given moment along the journey, the traveling twin would be comoving with some set of inertial observers, and he could determine simultaneity according to that set. > > Because it seems like you're thinking because you can define "now" according > > to the isoclines of time of the home-twin, that we cannot just as easily > > define "now" according to the isoclines of time of the traveling twin. > > You can define simultaneity (the meaning of "now") however you like. Yes. You can. I'm not the one arguing otherwise. I'm trying to point to the infinite number of ways that distant now can be defined, as a function of the instantaneous velocity of the observer. You've been arguing that the stay-at-home twin has the monopoly on the meaning of "now" and has the only relevant concept. > Basically > this is so because over macroscopic distances it simply does not matter -- > Nature certainly does not use such notions. So this is just a word game; one > that is irrelevant to physics. > You believe this is all a word game? You genuinely believe that traveling at 99% of the speed of light does not really affect people's perception of simultaneity? You think it only changes the words they use to describe it, and they are only playing word-games? > > You > > seem to regard the home-twin's isoclines of simultaneity as "correct" and the > > traveling twin's isoclines of simultaneity as "incorrect". > > No. I just think that what I described is what an astronaut would actually want > to know. The "CADO frame" yields ages that do not behave like ages "ought" to > behave (monotonically increasing); my approach does. > Pedagogically speaking, though, what is the benefit of ignoring the unexpected and interesting results of a theory, and only focusing on the expected results, where time behaves like it "ought" to. > > And so to get this "correct" idea of simultaneity, you stipulate that the > > traveling twin must be "immediately stopped in the home twin's inertial > > frame" But exactly how you envision this "stopping", within the context of > > the thought experiment? > > The stopping is just as valid as any other part of the gedanken. > > > Are you picturing something like an "instantaneous stop"? > > Yes. That's what I said: "immediately stop, right here and now". How long the > traveling twin remains stopped is irrelevant. > > Tom Roberts It doesn't really answer the question. You're not really incorporating the observations of the traveling twin into the thought experiment. You're using the observations of an assistant comoving with the stay-at-home twin in the location of the traveling observer.
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| From | Tom Roberts <tjroberts137@sbcglobal.net> |
|---|---|
| Date | 2017-07-12 10:13 -0500 |
| Message-ID | <7_idnfPSpNgEofvEnZ2dnUU7_83NnZ2d@giganews.com> |
| In reply to | #424549 |
On 7/11/17 7/11/17 - 3:40 PM, Jonathan Doolin wrote: > I agree that distant co-accelerating observers are impossible. > > The twin paradox scenario does not require the existence of co-moving > assistants for either the stay-at-home twin, or the traveling twin. Yes. Neither does the CADO frame for an accelerating observer. But the latter answer is what those "impossible" co-accelerating and co-moving distant assistants would measure. I leave out the HUGE difficulty of determining where to place those distant assistants, and how to determine how they should move in order to remain co-moving and co-accelerating with the observer herself. Indeed there are physical situations in which it is simply not possible to have such assistants. > And in the same sense that "distant now" is well defined at any given moment > for the stay-at-home twin, distant now is also well defined at any given > moment for the traveling twin. Not true. The stay-at-home twin is at rest in an inertial frame, and that provides a natural and unique meaning of "now" throughout spacetime (here assumed to be flat), including distant locations. But the traveling twin is not at rest in any inertial frame, and for her there is no natural or unique meaning of "now" at distant points. CADO is one possibility, what I suggested is another, and there are myriad other possibilities. They are ALL equally valid, and NONE of them has priority. >> You can define simultaneity (the meaning of "now") however you like. > > Yes. You can. I'm not the one arguing otherwise. I'm trying to point to the > infinite number of ways that distant now can be defined, as a function of the > instantaneous velocity of the observer. > > You've been arguing that the stay-at-home twin has the monopoly on the > meaning of "now" and has the only relevant concept. No I haven't. I never said or implied "monopoly". But I do think that for the case of an astronaut navigating around the galaxy at relativistic speeds, if she thought about "how old are my relatives back on earth?", the answer I gave is MUCH closer to what she would want to know than is the "CADO frame". A much better, more relevant, and unambiguous question is: "How old will my distant relatives be when I return to them, and how old will I be?" During the trip this of course depends on how she returns -- this does not resolve the inherent ambiguity of such questions, but it does change it from an ARBITRARY convention to a physical choice among potential paths to home. >> Basically this is so because over macroscopic distances it simply does not >> matter -- Nature certainly does not use such notions. So this is just a >> word game; one that is irrelevant to physics. > > You believe this is all a word game? Yes. > You genuinely believe that traveling at > 99% of the speed of light does not really affect people's perception of > simultaneity? No. NOT AT ALL. You completely misinterpret what I said. The word game is about "how old are my distant relatives right now?" -- THAT concept is HIGHLY ambiguous; fortunately it is not used in physics [#]. [#] "All physics is local." -- Einstein and others. Certainly this applies to EVERY ONE of our current physical theories. Tom Roberts
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-13 10:07 -0700 |
| Message-ID | <010dfcd0-41d9-4415-a282-89d19e7656f7@googlegroups.com> |
| In reply to | #424616 |
On Wednesday, July 12, 2017 at 10:13:36 AM UTC-5, tjrob137 wrote: > On 7/11/17 7/11/17 - 3:40 PM, Jonathan Doolin wrote: > > I agree that distant co-accelerating observers are impossible. > > > > The twin paradox scenario does not require the existence of co-moving > > assistants for either the stay-at-home twin, or the traveling twin. > > Yes. Neither does the CADO frame for an accelerating observer. But the latter > answer is what those "impossible" co-accelerating and co-moving distant > assistants would measure. > > I leave out the HUGE difficulty of determining where to place > those distant assistants, and how to determine how they should > move in order to remain co-moving and co-accelerating with the > observer herself. Indeed there are physical situations in which > it is simply not possible to have such assistants. > You've already brought this up. "comoving" and "co-accelerating" are, in fact, mutually exclusive. If an accelerating body is to stay rigid (hence co-moving) in fact, the back of the object must accelerate at a greater rate than the front. > > And in the same sense that "distant now" is well defined at any given moment > > for the stay-at-home twin, distant now is also well defined at any given > > moment for the traveling twin. > > Not true. The stay-at-home twin is at rest in an inertial frame, and that > provides a natural and unique meaning of "now" throughout spacetime (here > assumed to be flat), including distant locations. But the traveling twin is not > at rest in any inertial frame, and for her there is no natural or unique meaning > of "now" at distant points. CADO is one possibility, The traveling twin is always at rest in an inertial frame. But it is only at rest within each frame for zero time. And that's essentially what CADO is. But it is not just a possibility. It is the unique answer to the specific question "At any given moment, what events are simultaneous with the observations of the traveling twin from the perspective of the traveling twin." > what I suggested is > another, and there are myriad other possibilities. They are ALL equally valid, What you suggested is the unique answer to "At any given moment, what events are simultaneous with the observations of the traveling twin, from the perspective of the stay-at-home twin" > and NONE of them has priority. > But if you ask a non ambiguous question, the correct answer has priority. > >> You can define simultaneity (the meaning of "now") however you like. > > > > Yes. You can. I'm not the one arguing otherwise. I'm trying to point to the > > infinite number of ways that distant now can be defined, as a function of the > > instantaneous velocity of the observer. > > > > You've been arguing that the stay-at-home twin has the monopoly on the > > meaning of "now" and has the only relevant concept. > > No I haven't. I never said or implied "monopoly". > > But I do think that for the case of an astronaut navigating around the galaxy at > relativistic speeds, if she thought about "how old are my relatives back on > earth?", the answer I gave is MUCH closer to what she would want to know than is > the "CADO frame". > > A much better, more relevant, and unambiguous question is: "How > old will my distant relatives be when I return to them, and how > old will I be?" During the trip this of course depends on how > she returns -- this does not resolve the inherent ambiguity of > such questions, but it does change it from an ARBITRARY > convention to a physical choice among potential paths to home. > > >> Basically this is so because over macroscopic distances it simply does not > >> matter -- Nature certainly does not use such notions. So this is just a > >> word game; one that is irrelevant to physics. > > > > You believe this is all a word game? > > Yes. > > > You genuinely believe that traveling at > > 99% of the speed of light does not really affect people's perception of > > simultaneity? > > No. NOT AT ALL. You completely misinterpret what I said. > > The word game is about "how old are my distant relatives right now?" -- THAT > concept is HIGHLY ambiguous; fortunately it is not used in physics [#]. > > [#] "All physics is local." -- Einstein and others. Certainly > this applies to EVERY ONE of our current physical theories. > > Tom Roberts There are many valid and unambiguous questions that a traveling twin might be asked. He might feel that some of these questions are more relevant than others (1) What events did you see during that observation you made? (2) What events were simultaneous from your own point-of-view with that observation you made? (3) What events were simultaneous from the stay-at-home twin's point-of-view with that observation you made? (4) How old will my distant relatives be when I return to them, and how old will I be? (5) How old were your relatives when they sent that signal you received? (6) How old will your relatives be when they receive this signal you're sending? All of these questions are unambiguous, and have unique correct answers. Of course, you can ask ambiguous questions, as well, such as (7) "how old are my relatives back on earth?" But the ambiguity of this question is not because the concept of distant simultaneity is "ambiguous" It is because the concept of distant simultaneity is "observer dependent" When dealing with observer dependent ideas, a question is ambiguous unless it specifies the observer or the status of the observer. "Which direction are we from them" could be answered simply "to the right" "Which direction are they from us" could be answered simply "in front." A more ambiguous question is still valid, such as "what direction are these ships from each other?" But if someone still answered "in front" or "to the right" it's incorrect, since it fails to acknowledge "in front" and "to the right" are observer dependent directions. Clear answers would include "our ship is facing their ship's right side." or "they are passing to the right in front of us" or "we will pass to their left behind them" Even if the question is ambiguous, many correct and clear answers can be given. But all the correct answers would recognize that the positions and heading of the two ships were different, though well-defined. If an astronaut wondered "how old are my relatives back on earth?" any answer that did not recognize that her own simultaneity is well-defined, but different from her relatives' simultaneity, would be just as incorrect as an answer for the two ships that doesn't acknowledge that the two ships' "in front", "right" and "behind" are well defined, but different. Jonathan Doolin
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| From | Tom Roberts <tjroberts137@sbcglobal.net> |
|---|---|
| Date | 2017-07-14 20:04 -0500 |
| Message-ID | <BJidnTNaqaqO9_TEnZ2dnUU7_8zNnZ2d@giganews.com> |
| In reply to | #424752 |
On 7/13/17 7/13/17 12:07 PM, Jonathan Doolin wrote: > On Wednesday, July 12, 2017 at 10:13:36 AM UTC-5, tjrob137 wrote: >> I leave out the HUGE difficulty of determining where to place >> those distant assistants, and how to determine how they should >> move in order to remain co-moving and co-accelerating with the >> observer herself. Indeed there are physical situations in which >> it is simply not possible to have such assistants. > > "comoving" and "co-accelerating" are, in fact, mutually exclusive. > If an accelerating body is to stay rigid (hence co-moving) > in fact, the back of the object must accelerate at a greater rate > than the front. Yes. Think about what this means for the "CADO frame" -- it is designed to give the current age of a distant object, using the (accelerated) observer's notion of simultaneity. To make sense, it must be possible to verify the CADO calculation by using a real assistant at the location of the distant object. But if that assistant is not both co-moving and co-accelerating, why would one think this has any relevance at all to the observer? > [CADO] is the unique answer to the specific question > "At any given moment, what events are simultaneous with > the observations of the traveling twin > from the perspective of the traveling twin." Not quite. It is not "unique" at all, because simultaneity is ARBITRARY. [CADO] is the unique answer to the specific question "At any given moment, what events are simultaneous with the observations of the traveling twin from the perspective of the traveling twin, USING THE TRAVELING TWIN'S INSTANTANEOUSLY CO-MOVING INERTIAL FRAME." As always, you MUST specify what you mean by "simultaneous". > But if you ask a non ambiguous question, > the correct answer has priority. There is no "correct" answer here, because there are MANY potential meanings of "simultaneous", and each gives a different answer. Ambiguous questions have no answer, but they might have many potential answers. Tom Roberts
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-15 13:49 -0700 |
| Message-ID | <c02ec297-5ebd-4190-9a02-96fe18da165d@googlegroups.com> |
| In reply to | #424939 |
On Friday, July 14, 2017 at 8:04:27 PM UTC-5, tjrob137 wrote:
> On 7/13/17 7/13/17 12:07 PM, Jonathan Doolin wrote:
> > On Wednesday, July 12, 2017 at 10:13:36 AM UTC-5, tjrob137 wrote:
> >> I leave out the HUGE difficulty of determining where to place
> >> those distant assistants, and how to determine how they should
> >> move in order to remain co-moving and co-accelerating with the
> >> observer herself. Indeed there are physical situations in which
> >> it is simply not possible to have such assistants.
> >
> > "comoving" and "co-accelerating" are, in fact, mutually exclusive.
> > If an accelerating body is to stay rigid (hence co-moving)
> > in fact, the back of the object must accelerate at a greater rate
> > than the front.
>
> Yes. Think about what this means for the "CADO frame" -- it is designed to give
> the current age of a distant object, using the (accelerated) observer's notion
> of simultaneity. To make sense, it must be possible to verify the CADO
> calculation by using a real assistant at the location of the distant object. But
> if that assistant is not both co-moving and co-accelerating, why would one think
> this has any relevance at all to the observer?
>
Are you still determined to misrepresent CADO
by claiming that it uses co-accelerating observers?
CADO uses comoving inertial reference frames.
From moment to moment, you don't follow any distant observers,
You use different sets of observers in each moment.
> > [CADO] is the unique answer to the specific question
> > "At any given moment, what events are simultaneous with
> > the observations of the traveling twin
> > from the perspective of the traveling twin."
>
> Not quite. It is not "unique" at all, because simultaneity is ARBITRARY.
>
> [CADO] is the unique answer to the specific question "At any given moment, what
> events are simultaneous with the observations of the traveling twin from the
> perspective of the traveling twin, USING THE TRAVELING TWIN'S INSTANTANEOUSLY
> CO-MOVING INERTIAL FRAME." As always, you MUST specify what you mean by
> "simultaneous".
>
> > But if you ask a non ambiguous question,
> > the correct answer has priority.
>
> There is no "correct" answer here, because there are MANY potential meanings of
> "simultaneous", and each gives a different answer.
>
> Ambiguous questions have no answer, but they might have many potential answers.
>
> Tom Roberts
I'm reminded of a t-shirt I have, which has a right-triangle with sides 3 cm and 4 cm, and hypotenuse, labeled "x". The problem asks "find x"
A student, either misunderstanding the intent of the question or finding it ambiguous, draws a circle around the letter "x" and says, "Here it is!"
So, of course, they have succeeded in some interpretation of the instruction "find x".
Of course, if the student were present in class in the preceding days, quite likely, he would have heard the teacher explaining what he means by "find x" in some example problems.
I could also imagine someone taking that same test, and insisting that the meaning of "x" is arbitrary, and there can not possibly be an answer, because of the ambiguity of the question.
That second student isn't quite so funny. The one with the joke answer, ("Here it is!") at least understood that different interpretations of the question actually have answers however the question is interpreted.
But The student who answers 'the meaning of "x" is arbitrary so the question has no answer' is just making a case for the futility of the explanation of ideas, and the impossibility of communicating meaning.
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| From | The Starmaker <starmaker@ix.netcom.com> |
|---|---|
| Date | 2017-07-15 14:26 -0700 |
| Message-ID | <596A887A.519@ix.netcom.com> |
| In reply to | #425072 |
The Secret to Einstein's Twin Paradox is... he never meant for the twin to return. That is everyone's mistake.
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| From | Tom Roberts <tjroberts137@sbcglobal.net> |
|---|---|
| Date | 2017-07-17 20:20 -0500 |
| Message-ID | <DbWdnRla3ZbX__DEnZ2dnUU7_8zNnZ2d@giganews.com> |
| In reply to | #425072 |
On 7/15/17 7/15/17 3:49 PM, Jonathan Doolin wrote: > CADO uses comoving inertial reference frames. Yes. A different one at each and every instant. The "CADO frame" computes at any instant what a co-moving INERTIAL observer located at the distant object would measure. Why do you think this is in any way relevant to the ACCELERATING observer? The co-moving and co-accelerating distant assistants I mentioned are at least directly related to the observer, except that in general they are impossible. > From moment to moment, you don't follow any distant observers, > You use different sets of observers in each moment. You say "observers" where I said "assistants", to the same effect. THINK about how silly it is conceptually to be constantly switching sets of assistants like that.... As I have said many times: the "CADO frame" is a solution looking for a problem. There is NOTHING an accelerating observer can do to define "the current age of a distant object" that is unique, sensible, and which behaves like the current age of an object ought to behave (monotonically increasing). The suggestion I made is all of that except unique. Hmmm. Among all sensible approaches in which the current age of the distant object increases monotonically, I conjecture that my suggestion is unique. Here "sensible" means "directly related to an arbitrarily-accelerating observer and the distant object". Tom Roberts
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| From | Jonathan Doolin <good4usoul@gmail.com> |
|---|---|
| Date | 2017-07-20 07:25 -0700 |
| Message-ID | <62f6f3a2-75e1-4f78-afc4-a39e1706e161@googlegroups.com> |
| In reply to | #425408 |
On Monday, July 17, 2017 at 8:20:18 PM UTC-5, tjrob137 wrote: > On 7/15/17 7/15/17 3:49 PM, Jonathan Doolin wrote: > > CADO uses comoving inertial reference frames. > > Yes. A different one at each and every instant. > Right. > The "CADO frame" computes at any instant what a co-moving INERTIAL observer > located at the distant object would measure. Essentiallu > Why do you think this is in any way > relevant to the ACCELERATING observer? > The opinion of the observer really doesn't matter here in determining the answer "What events are simultaneous with each of your observations" The answer is "The same set of events picked out by the CADO frame" > The co-moving and co-accelerating distant assistants I mentioned are at least > directly related to the observer, except that in general they are impossible. > It seems to me you may be arguing that other objects must be co-moving and co-accelerating in order to be "relevant" to the traveling twin. I don't know how to explain how ridiculous your argument is here. But I can come up with an analogy. If I am riding in an airplane, and west is to my left, and north is in front of me. The plane turns 90 degrees to the right, and now, east is in front of me, and north is to my left. The wing-tip and the front of the plane are co-facing, and co-moving assistants. But I have no co-facing and co-moving assistants beyond the wingtip of the plane. (Such assistants would have to travel great distances at enormous speeds as the plane turned) But far distant co-facing and co-moving assistants are not required nor relevant for defining the changing front and left directions from the plane. Indeed, when an airplane turns right, it is quite surprising if some distant object maintains its position relative to the plane. > > From moment to moment, you don't follow any distant observers, > > You use different sets of observers in each moment. > > You say "observers" where I said "assistants", to the same effect. THINK about > how silly it is conceptually to be constantly switching sets of assistants like > that.... > Again, based on the analogy, I'm flying in the plane, and turning right, taking 90 pictures as I turn 90 degrees. Each frame of the picture is going to have a different object at the zero-degree mark. You could make the argument "It's silly to be switching 'forward' assistants like that." But if you want to turn the plane, you really don't have any choice in which object is forward from you, moment-to-moment, any more than you have a choice which distant events are simultaneous with your current observation. > As I have said many times: the "CADO frame" is a solution looking for a problem. > There is NOTHING an accelerating observer can do to define "the current age of a > distant object" that is unique, sensible, and which behaves like the current age > of an object ought to behave (monotonically increasing). The suggestion I made > is all of that except unique. > I've had surreal arguments with you in the past where I have said that if I turn right, objects in front of me move to my left, and objects behind me move to my right. To which you responded, obviously those objects do not really move, and that I do not know what the word "move" means. Unfortunately, this is the only argument I really have. And I can really only acknowledge that you have a form of invincible ignorance that I alone cannot cure you of, that each observer's coordinate system is unique, orthogonal, sensible. But of course it does not behave like you would like it to, over time, because observer's can do things like turn around, change velocity, accelerate. And events will move forward and backward in time and space, as the observer does these things, and not everything is monotonically increasing, as you feel it "ought" to be. > Hmmm. Among all sensible approaches in which the current age of > the distant object increases monotonically, I conjecture that my > suggestion is unique. Here "sensible" means "directly related to > an arbitrarily-accelerating observer and the distant object". > > Tom Roberts If your measure of "merit" is how well your model conceals some of the surprising phenomena predicted by a theory, then I suppose restricting yourself to the point-of-view of the stay-at-home twin will work, and so will using Dolby-and-Gull's radar time. But since ages of distant objects beyond the rindler horizon of an accelerating observer are actually decreasing, it doesn't make sense to constrain yourself to any suggestion which makes you falsely conclude otherwise.
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| From | kenseto <setoken@att.net> |
|---|---|
| Date | 2017-07-05 07:50 -0700 |
| Message-ID | <450a9dae-1afa-458f-b5aa-89a6dfb370a6@googlegroups.com> |
| In reply to | #423903 |
On Monday, July 3, 2017 at 6:52:14 PM UTC-4, tjrob137 wrote: > On 7/3/17 7/3/17 10:18 AM, Jonathan Doolin wrote: > > On Sunday, July 2, 2017 at 1:35:04 PM UTC-5, Mike_Fontenot wrote: > >> On 7/1/17 11:29 AM, Tom Roberts wrote: > >>> But as long as the observer keeps track of his speed relative to the > >>> original inertial frame [#], then from the value of his own watch he can > >>> continuously keep track of the time coordinate of the inertial frame (by > >>> inverting the equation for "time dilation" relative to an inertial > >>> frame). > > > > I think it is confusing here, Tom, that you refer to "the time coordinate of > > the inertial frame". I think, below, Mike guessed that you mean "the time > > coordinate of the inertial frame AT the position of the traveling twin." > > But the value of the time coordinate of an inertial frame is independent of > location -- it has the same value everywhere, because that's what those words > mean (when applied to an inertial frame, which is one of the main reason > inertial frames are so useful). So your addition adds nothing. The time coordinate of an inertial frame is independent of location only if the inertial frame is in a state of absolute rest. But no inertial frame is in a state of absolute rest. > > > Mike then correctly points out, if this is what you meant, then that time > > would be proceeding, not SLOWER than the traveling twin's clock, but FASTER > > than the traveling twin's clock. > > Yes, of course (unless the traveling twin stops somewhere at rest in that > inertial frame). Any astronaut capable of traveling at relativistic speed would > know this. > > Tom Roberts
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| From | Tom Roberts <tjroberts137@sbcglobal.net> |
|---|---|
| Date | 2017-07-03 18:26 -0500 |
| Message-ID | <teWdnR4fsNhfT8fEnZ2dnUU7_8zNnZ2d@giganews.com> |
| In reply to | #423826 |
On 7/2/17 7/2/17 1:35 PM, Mike Fontenot wrote: > On 7/1/17 11:29 AM, Tom Roberts wrote: >> But as long as the observer keeps track of his speed relative to the >> original inertial frame [#], then from the value of his own watch he can >> continuously keep track of the time coordinate of the inertial frame (by >> inverting the equation for "time dilation" relative to an inertial frame). >> That time coordinate is, of course, also the age of the sender (who remains >> at rest in that frame). This uses the simultaneity of that inertial frame, >> not the observer's "CADO frame" (which I think is irrelevant and useless >> here). >> >> In some distant future in which spaceships travel at relativistic speeds, >> this is surely what an astronaut would want to know about the age of >> relatives back on earth, not anything related to the "CADO frame". >> Moreover, it is more straightforward to calculate. >> >> [#] Any astronaut would surely do this automatically. >> > > In terms of the CADO terminology,[...] You're too wound up in "CADO terminology" and are not asking yourself: what would the astronaut want to know? A calculation in which the astronaut's relatives alternately age rapidly or get younger, as he happens to change direction, is essentially useless to him -- aging simply does not behave like that. What I suggested answers this rather obvious question: if I were to immediately stop in their inertial frame, right here and now, how old would they be? Moreover, calculations of their age advance continuously and monotonically (as aging does). Your CADO_T(t), on the other hand, does not do that, and is completely artificial. And useless. You seem to not understand what "time dilation" actually means, and how it is measured: > [during a long inertial leg of his trip] if the astronaut uses his own > measurements and elementary calculations, he will find that the home twin is > indeed ageing more slowly than he is To make such a MEASUREMENT, the astronaut would need a co-moving assistant with a clock synchronized in his current inertial frame, who is pre-positioned so he "just happens" to pass by Home at the time of the measurement. The assistant then transmits the result to the astronaut, who learns much later how old his relatives were BACK THEN (when the measurement was made). That is OUTRAGEOUS and useless -- it does not begin to answer "how old are they now?". > What would make the astronaut unhappy would be to have to adopt a "viewpoint" > for himself about the home twin's current age that disagrees with his own > measurements and elementary calculations. But the astronaut ALONE cannot make such measurements. And the assistants required are simply not possible (except in gedankens). Moreover the whole notion is useless: any astronaut who can travel with relativistic speeds will know of the difficulties involved, and will simply have to accept that while traveling the "age of his home-bound relatives" is ambiguous and not worth worrying about. Such considerations of "how old are they now" over such a spacelike interval is akin to counting angels dancing on a pinhead, and just as useful. Tom Roberts
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