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Twin paradox negation. 
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#199
Oct1908, 09:44 PM

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#200
Oct1908, 10:22 PM

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*I.e. no net transverse/gravitational Doppler effect 


#201
Oct1908, 11:27 PM

P: 212

Does the traveled clock end up, as Einstein suggested, lagging behind the 'stationary' clock? Does that traveled clock 'go more slowly' than the stationary clock in order to end up lagging behind same? Did the HafeleKeating clocks 'go more slowly' than the laboratory clocks? i.e. did they tick over at a slower rate than the laboratory clocks after gravitational time variation effects were taken into account and removed from the equations as Will's did in 'Was Einstein Right?'? I'm specifically talking about what physically happened to those clocks not what a Minkowski spacetime diagram 'shows'. You wrote  "...the SR and GR effects cancel each other out." however was Einstein's comment regarding clocks at the equator and at one of the poles applicable to SR? Was the paper to which you refer published in a peerreviewed science journal? Has it been accepted by the physics community? 


#202
Oct2008, 12:10 AM

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P: 8,371

Audoin and Guinot, p9, 10:
"The postulate leaves no room for differential ageing of the various natural phenomena. ... Although it has never yet been found to fail, it may one day be brought into question by experimental progress." "...Einstein's general relativity has appeared on the scene. According to this theory, only local time can be directly measured with a clock. In other words, it is the proper time of this clock or an observer in the immediate vicinity that is measured. The time ...over an extended region of space including, for example, the Solar System, is just a coordinate time freely chosen ... and to which no physical reality is attributed." http://books.google.com/books?hl=en&...esult#PPA10,M1 


#203
Oct2008, 12:29 AM

P: 77

Shouldn't clocks on opposite sides of the planet serve to test this theory? They are facing away from one another and both under 1G. According to Relativity, what's the difference?
Gravity is acceleration. The real challenge is how to actually observe one from the perspective of the other. The "paradox" is really only an observatory phenomena. Only if one of them accelerates more than the other will there be any real dilation and that will take place on the clock under more acceleration (resulting in a higher velocity relative to 'Big Ben'). When the faster clock returns to 1G all observers will notice the dilation effect on the faster clock, even relative to the paradox. Wrap your head around that :) 


#204
Oct2008, 02:23 AM

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#205
Oct2008, 08:52 AM

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Note, that clocks A and B never meet so you have to define the endpoints of each worldline completely separately. One typical choice would be to choose the intersection of each worldline with a "beginning" and an "ending" hypersurface of simultaneity, usually defined using Einstein synchronization in the rest frame of the hub. Now, if you do that you find that the interval along worldline A is shorter than the interval along worldline B. So if clock A and B are set to zero at the beginning then clock A will read less than clock B at the ending. Each clock still measures the same 1 second/lightsecond along their respective paths, but clock A just travels a shorter path. In case you missed them in the paragraph above that is a yes for your "lagging" question and a no for your "go more slowly" question. In (Euclidean) geometrical terms this scenario is analogous to the fact that the distance from the Atlantic coast to the Pacific coast is shorter when measured from Veracruz to Acapulco than when measured from New York to Los Angeles. 


#206
Oct2008, 08:59 AM

P: 1,060

Hello cos.
I feel that eventually this frame will slowly come to an end because people will realize that you cannot be convinced by logical reasoning. You will feel able to claim you are right by default because people have given up, not because they think you are right but through sheer frustration. I hereby claim the dubious honour of being the first to give up, unless someone in some other frame has already done so. Matheinste 


#207
Oct2008, 09:00 AM

P: 1,545

But you make it clear you do not want to understand SR  I can only assume you intentionally just want to be argumentative and I do see why you came to these forums at all. Waste others time but not mine  I’ll unsubscribe from this thread. IMO a mentor should lock it simply as a lost cause; you are not listening to anyone. 


#208
Oct2008, 06:40 PM

P: 212

On the basis that they do meet we, presumably, do not "have to define the endpoints of each worldline completely separately." The rest of your post applies to the mathematically determined Minkowski spacetime concept which, as I have pointed out on several occasions, is not  according to Einstein  reality. I note that you declined to respond to my question regarding the HKX and other salient points so I will repeat same: *********** Did the HafeleKeating clocks 'go more slowly' than the laboratory clocks? i.e. did they tick over at a slower rate than the laboratory clocks after gravitational time variation effects were taken into account and removed from the equations as Will's did in 'Was Einstein Right?'? I'm specifically talking about what physically happened to those clocks not what a Minkowski spacetime diagram 'shows'. Was the paper to which you refer published in a peerreviewed science journal? Has it been accepted by the physics community? *********** Here is another question which although applicable to GR also applies to Einstein's chapter 4 SR depiction specifically a polygonal line clock A relocation but which has similarly been ignored by others in this thread  an observer is located on top of a mountain; he notes that a clock at that location ticks over at the same rate as his own clock which is obviously ticking over at it's 'normal' rate. He moves to sealevel and again notes that a clock at that location ticks over at the same rate as his own clock  which is still ticking over at it's 'normal' rate. Does he insist that the clock at the top of the mountain and the clock at sealevel are ticking over at the same rate as each other as determined by his observations or does he apply his knowledge of the Wallops Island experiment and general theory and realize that although the sealevel clock appears to be ticking over at the same rate as the mountain top clock it is physically ticking over at a slower rate? An astronaut comes to a stop at the end of his outwardbound journey and notes the rate of operation of his clock. He then accelerates and again looks at his clock which, although appearing to be ticking over at a normal rate, is physically ticking over at a slower rate than it was before he started accelerating in the same way that the above mentioned mountaindescending observer's clock ticks over at a slower rate than it did before he started moving. My specific interest is in relation to what is physically happening to the clocks! Although I am of the opinion that this analogy is highly relevant it will most likely be emitted from your response as were the abovereferred to salient points. 


#209
Oct2008, 06:54 PM

P: 77

Sorry, I couldn't help myself. 


#210
Oct2008, 07:12 PM

P: 411

JesseM post 187;
A is not moving at .8c, therefore his clock will not experience B's dilation, and B cannot apply his dilation to A's clock. 


#211
Oct2008, 07:50 PM

Sci Advisor
P: 8,470

Do you agree that in the frame where B is moving at 0.8c, the ticks of B's clock are slowed down by a factor of 0.6, so when 15 seconds of coordinate time pass in this frame, B ticks forward by 15*0.6 = 9 seconds? Do you agree that after A comes to rest in this frame, A's clock thereafter ticks at the normal rate in this frame, so when 15 seconds of coordinate time pass in this frame, A ticks forward by 15 seconds? Do you agree that if B is attached to a rod which is 20 ls long in B's rest frame (which is also the rod's rest frame, call it frame #1), then in this second frame where B and the rod are moving at 0.8c (call this frame #2), the rod will be 12 ls long? Please tell me specifically whether you disagree with any of these 3 statements (if you do, then there is some error in your understanding of inertial frames in SR). 


#212
Oct2008, 07:51 PM

P: 212

Thanks for the correction. The error was due to my typical rash hastiness in responding. 


#213
Oct2008, 08:02 PM

P: 212

One down  3(?) to go. 


#214
Oct2008, 08:09 PM

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#215
Oct2008, 08:49 PM

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P: 8,371

Below are quotes from Einstein's 1905 "On the Electrodynamics of Moving Bdies". Bolding added by me.
http://www.fourmilab.ch/etexts/einstein/specrel/www/ http://www.prophysik.de/Phy/pdfs/ger_890_921.pdf Section 1: And in fact such a definition is satisfactory when we are concerned with defining a time exclusively for the place where the watch is located; but it is no longer satisfactory when we have to connect in time series of events occurring at different places, orwhat comes to the same thingto evaluate the times of events occurring at places remote from the watch. ...... We have not defined a common "time" for A and B, for the latter cannot be defined at all unless we establish by definition that the "time" ... It is essential to have time defined by means of stationary clocks in the stationary system, and the time now defined being appropriate to the stationary system we call it "the time of the stationary system." Section 2: So we see that we cannot attach any absolute signification to the concept of simultaneity, but that two events which, viewed from a system of coordinates, are simultaneous, can no longer be looked upon as simultaneous events when envisaged from a system which is in motion relatively to that system. Section 4: What is the rate of this clock, when viewed from the stationary system? Edit: I do not wish to give the impression that truth is determined by quoting authority. But I believe the quotes are helpful for putting the discussion in context. 


#216
Oct2008, 09:27 PM

P: 212

Re: Section 4: What is the rate of which clock? My reference is only to the astronaut's clock when viewed in his reference frame. I trust that I did not give the impression that, in my opinion, truth is determined by quoting authority. The only 'truth' to which I refer is the fact that it is true that Einstein presented the quoted depictions. 


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