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Relativity of Simultaneity 
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#19
Feb912, 09:34 AM

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#20
Feb912, 10:10 AM

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You seem to have already a difficulty with getting two distant clocks synchronized according to yourself, despite your suggestion that all clocks will be automatically synchronized with all other clocks according to everyone. Nevertheless it was only an introduction to the next question: how can you do that in such a way that everyone will agree? 


#21
Feb912, 05:57 PM

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#22
Feb912, 06:53 PM

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#23
Feb912, 06:59 PM

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#24
Feb912, 07:24 PM

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I don't think it takes a formal theory to believe that time is absolute, that just seems natural and normal, don't you think? But once you measure the speed of light to be constant, it's only natural and normal to come up with a theory that retains absolute time, don't you think?



#25
Feb912, 08:50 PM

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In the last sentence, do you mean, once you measure the speed of light to be constant, it's only natural and normal to come up with a theory abandons absolute time? 


#26
Feb912, 09:26 PM

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#27
Feb1012, 01:06 AM

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According LET clocks tick at different rates for mechanical reasons, and so absolute simultaneity prevails. According to Einsteinian relativity, clocks tick at different rates becuse "time itself slows down"; is it because "time itself slows down" in certain reference frames that RoS prevails? I presume it must be, because if time didn't slow down, and slower ticking clocks were the result of the mechanics of the clock then, as per LET, absolute simultaneity would prevail. Alternatively, if time itself didn't slow down and clocks all ticked at the same rate, then absolute simultaneity would prevail. 


#28
Feb1012, 02:19 AM

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A similar thing happened earlier in classical mechanics: Newtonian mechanics distinguishes absolute velocity that cannot be measured as well as relative velocity that can be measured. Classical mechanics only deals with relative velocity. 


#29
Feb1012, 02:43 AM

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Absolute velocity is a simple yes or no answer to the question, is there velocity? 


#30
Feb1012, 03:52 AM

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I'm going to stipulate, for the sake of argument, that LET is the correct understanding of the way nature works. That means that there truly is an immovable ether and light propagates at c only with respect to the rest state of that ether. Time and space are absolutes. And because of the mechanical properties of the ether and the way that matter interacts with it, when matter moves through the ether, it contracts along the direction of motion. Also, any physical clock made of matter will keep track of the absolute time correctly only if it is stationary in the ether. If it is moving, the operation of the clock makes it slow down and so it is no longer keeping the correct time. The Lorentz factor correctly describes how much a moving clock slows down and how physical objects are contracted along the direction of motion. This is the stipulated truth about nature. Now let's suppose an observer who is stationary in that ether has some measuring rods and some accurate, stable clocks and a mirror. When he attempts to measure the round trip speed of light, he gets the correct answer because his rulers and clocks are normal since they are not moving. Now let's suppose that he gets in a spaceship and accelerates to a high rate of speed with respect to the ether. This will cause his clocks to slow down and his rulers to contract when aligned with the direction of motion. When he repeats his measurement of the speed of light, what will happen? Well we know if he aligns his experiment so that the light has to travel against the ether to get to the mirror, it will take longer than when he was stationary. After it hits the mirror and reflects back, we know that it will take a shorter time than before because it is being carried along by the ether. Furthermore, we know that when he measures the distance between the mirrors, they will be closer together. As long as his clocks and rulers are modified by just the right amount, he will get the same measurement of the speed of light as he did before. But we know why he gets the same answer and that's because of length contraction and time dilation for matter moving through the ether. As a matter of fact, the moving observer will see everything exactly the same when he is moving as he did when he was stationary. He cannot tell that he is moving with repsect to the ether. Do you understand this? 


#31
Feb1012, 05:00 AM

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http://en.wikisource.org/wiki/The_Measure_of_Time It was found that even if we wanted to, we cannot detect absolute simultaneity. But if we wanted, we could define a truly "universal time" and synchronize all clocks accordingly.  http://gravitee.tripod.com/definitions.htm (press "cancel" and scroll to "SCHOLIUM") Harald 


#32
Feb1012, 07:20 AM

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My understanding is that RoS prevails, or perhaps more accurately, RoS is a consequence of the fact that [local*] clocks tick at different rates  if they didn't then absolute simultaneity would prevail. According to LET, as you have outlined above, clocks slow down for mechanical reasons (presumably this is true even when LET is stripped of everything but the absolute rest frame). That much I understand. The question pertains to Einsteinian relativity. My understanding is that RoS is what results when [local*] clocks tick at different rates  is that much correct? As mentioned, LET postulates that this is down to the mechanics of the clock (as outlined above)  what, according to Einsteinian relativity, is the reason that [local*] clocks tick at different rates? *Just in case the term "local" isn't used in Einsteinian relativity, what I mean is the clock at rest in a given FoR 


#33
Feb1012, 09:53 AM

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The oneway speed of light cannot be observed and cannot be measured. That is why we are free to make any postulate regarding it. For example, let's say that we place a mirror 10 feet away from our light source and our timer. We turn on the light at the exact moment we start the timer. When we detect the reflected light and stop the timer it reads 20 nanoseconds. We have the option of dividing the times for the two trips any way we want. We can say that it took 0 time for the light to get to the mirror and 20 nanoseconds to get back or vice versa. Or we could say that it took 1 nanosecond to get to the mirror and 19 nanoseconds to get back. Or 2 and 18, 3 and 17, etc. Or we could say, like LET that we have to determine the division of the times based on how fast we think we are traveling with respect to ether when the roundtrip measurement assigns the times as equal. That claim supports the idea of an absolute time. Or we could say, like SR, that those times are equal every time we make the measurement which leads to the concept of relative time which is just another way of saying Relativity of Simultaneity. Please look again at Einstein's 1905 paper introducing Special Relativity. Look at the title of the first section. It's called "Definition of Simultaneity". Look at what he says in the third paragraph: We have to take into account that all our judgments in which time plays a part are always judgments of simultaneous events. If, for instance, I say, “That train arrives here at 7 o'clock,” I mean something like this: “The pointing of the small hand of my watch to 7 and the arrival of the train are simultaneous events.” Then read the rest of that section and see how he builds up a consistent definition of time in remote locations. Please study the first half, Part I, of his paper. If you don't understand something there, please ask a question. You need to understand Einstein's presentation if you want to understand Einsteinian relativity. I don't want to entertain any more questions that aren't sourced from Einstein. 


#34
Feb1012, 10:42 AM

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In order to obtain the Lorentz transformations from the Galilean transformations, one has to assume time dilation and Lorentz contraction (done by nature) as well as RoS (should be done by the experimentalist, by means of clock synchronization). Harald 


#35
Feb1012, 09:27 PM

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Just one quick question though, to see if I am even in the ball park with understanding this: am I at least [some way] right in thinking that if all clocks ticked at the same rate then absolute simultaneity would prevail; but because clocks tick at different rates RoS prevails? 


#36
Feb1012, 09:35 PM

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