Jesse, You ask me to choose between 1. and 2.
1. If B's proper age at this point in spacetime is T, then C's proper age at this point in spacetime must be T as well (i.e. their proper ages are "simultaneous" in the sense that they must reach the same age simultaneously). 2. If B and C's worldlines both pass through a specific point in spacetime P, and B's age is T1 when she passes through P, while C's age is T2 when she passes through P, then B must be at age T1 simultaneously with C being at age T2 (i.e. whatever two specific ages they have at P, they must reach those two ages simultaneously, even if the two ages are different) First I assume that by "passing through the same point in spacetime" you mean that the worldlines cross at P simultaneously by the operational definition of no light delay. 1. is true only in a SYMMETRIC case. In the symmetric case they would have the same ages as they pass through the same point P, but in that case they have the same ages during the WHOLE trip so no big surprise. 2. is true in all cases. The actual ages T1 and T2 at which they simultaneously cross will stand in a 1:1 correlation, but ONLY AT THAT POINT P because their ages could be different due to acceleration differences either before or after. There are two equivalent ways they can confirm their actual 1:1 age correlations in both (all cases) when they cross paths. First they can directly observe this 1:1 correlation by simply looking at each other's clocks as they pass. Normally this is not possible if two observers have relative motion with respect to each other, but in this case there is no time delay and the looking only takes a SINGLE MOMENT OF TIME, so even though the time RATES of each other's proper clocks are dilated in each other's frames, each can still actually read the correct proper time on the other's clock as they cross. (One might initially think it is impossible to read each others' clocks correctly due to the dilation of relative motion, or even if they passed with different accelerations, but this is not true in the case where they read as they cross. Each proper clock is ALWAYS reading the actual proper age. The apparent dilation effect is just due to the longer interval it takes for signals from that clock to reach the observer. But the signals received always display the real and actual proper age of the clock WHEN the signals were sent. So in the crossing case where there is only a single signal with NO time delay the clock reading received = the actual clock reading when the signal was sent. Note that this analysis points out that all proper clocks continually show the actual proper age of the clock when the signal was sent. So that real actual age is REALLY OUT THERE. Your imaginary 1:1 correlation problem just doesn't take into proper account the transmission time from the clock to the receiver. Just subtract the transmission time and you will get the actual 1:1 age correlation between when any proper age signal was sent and what proper time it was received.) Second they CAN CONFIRM the actual age correlation in ALL cases simply by exchanging light messages as they cross telling each other their actual ages which is an equivalent method. As they cross the light signal has no appreciable delay so whatever actual age they report will correlate to the actual age the other receives the signal. In this way crossing observers CAN UNambiguously determine the 1:1 correlation of their actual ages even if they are in relative motion. With this understanding your 1. is true of symmetric cases, and 2. is true of all cases... Edgar On Tuesday, March 4, 2014 12:19:27 PM UTC-5, jessem wrote: > > > > On Tue, Mar 4, 2014 at 8:37 AM, Edgar L. Owen <edga...@att.net<javascript:> > > wrote: > > Jesse, > > I'm interested in finding the truth, not in assigning blame. > > The important thing is we both now agree that there IS ALWAYS A > CORRELATION OF ACTUAL AGES between any two observers. > > The difference is I think it's an EXACT correlation, and you think that > it's ALMOST EXACT except for cases of extreme separation or motion. > > I think we have to analyze the age correlation from a POV that preserves > the actual relationship of the accelerations that are the ONLY cause of age > rate differences. Whereas you think we have to consider all possible views > irrespective of whether they properly preserve the relationship of causes > of age rate differences. My method provides an EXACT correlation. Your > method provides an ALMOST EXACT correlation in all but extreme cases. > > > Also now that I have pointed out the error in your Alice, Bob, Arlene, > Bart example do you agree my method does produce consistent, unambiguous > and transitive 1:1 correlations of proper ages among all observers? > > > So you are just going to COMPLETELY IGNORE my response, which pointed out > that your supposed "error" relied on using the ambiguous phrase "B's and > C's proper ages are simultaneous in p-time because they are at the same > place in spacetime" to describe my views, and interpreting it in a way that > I would never had agreed with? Again, this phrase could be interpreted two > possible ways: > > 1. If B's proper age at this point in spacetime in T, then C's proper age > at this point in spacetime must be T as well (i.e. their proper ages are > "simultaneous" in the sense that they must reach the same age > simultaneously). > > 2. If B and C's worldlines both pass through a specific point in spacetime > P, and B's age is T1 when she passes through P, while C's age is T2 when > she passes through P, then B must be at age T1 simultaneously with C being > at age T2 (i.e. whatever two specific ages they have at P, they must reach > those two ages simultaneously, even if the two ages are different) > > Your attempt to show an "error" in the phrase you invented to describe my > views depended on interpreting the phrase as meaning #1, but I never > asserted anything like #1, my position is described by #2. Do you think > statement #2 is still in "error"? PLEASE ANSWER THIS QUESTION YES OR NO. If > your answer is "yes, #2 is still in error" I suspect you are > misunderstanding something very basic about relativity...so if you do > answer "yes", please tell me if you would agree or disagree that in case > #2, the event of B's clock reading T1 and the event of C's clock reading T2 > both satisfy the OPERATIONAL definition of "same point in spacetime" that I > had given earlier involving light signals. > > On the other hand, if you would answer "no, statement #2 is not in error, > I agree that in this case T1 and T2 are simultaneous in absolute terms", > then please have another look at the specific numbers I gave for x(t), > coordinate position as a function of coordinate time, and T(t), proper time > as a function of coordinate time, for each observer, and then tell me if > you agree or disagree with the following two statements: > > For A: x(t) = 25, T(t) = t > For B: x(t) = 0, T(t) = t > For C: x(t) = 0.8c * t, T(t) = 0.6*t > For D: x(t) = [0.8c * t] + 9, T(t) = 0.6*t - 12 > > --given the x(t) functions for B and C, we can see that they both pass > through the point in spacetime with coordinates x=0, t=0. Given their T(t) > functions, we can see that B has a proper time T=0 at those coordinates, > and C also has a proper time T=0 at those coordinates. Agree or disagree? > > --given the x(t) functions for A and D, we can see that they both pass > through the point in spacetime with coordinates x=25, t=20. Given their > T(t) functions, we can see that A has a proper time T=20 at those > coordinates, and D has a proper time T=0 at those coordinates. Agree or > disagree? > > If you would agree with my statement #2 above, and you also agree with > these two statements, then this should be sufficient to show that the event > of B's proper time clock reading T=0 is simultaneous in p-time with the > event of C's proper time clock reading T=0, and that the event of A's > proper time clock reading T=20 is simultaneous in p-time with the event of > D's proper time clock reading T=0. But if you don't agree with this > conclusion, then answering the earlier questions will pinpoint the first > step in the argument that you disagree with. > > > > > > > > To address your new questions: > > > You have a funny idea of "addressing questions", one which doesn't involve > actually giving a direct ANSWER to any of the questions I asked in my post. > Again, I would request that when answering my questions, you actually QUOTE > THE QUESTION I ASKED and then respond to it in the next line, as I always > do with your questions. > > > > > > > Do you deny acceleration and gravitation produce real actual slowings of > clock rates and thus of real actual aging rates? > > > I would deny that in relativity there is any PHYSICAL way to define "real > actual slowings of clock rates". It's possible that some form of presentism > is METAPHYSICALLY true, and that there is a unique METAPHYSICAL truth about > how clocks slow relative to absolute time, but there is no PHYSICAL > experiment that would pick out one frame's views of how clock rates change > as more physically correct than any other frame's. > > Do you claim that the standard textbook assumptions and equations of > RELATIVITY ITSELF allow us to derive unique values for "real actual > slowings of clock rates"? (PLEASE ANSWER THIS QUESTION YES OR NO.) Or would > you agree that in order to find the "real actual slowings of clock rates", > we have to adopt some new postulates that are NOT part of mainstream > relativity? Among the questions in my previous post that your response > completely failed to address, I asked a question about what your basic > starting premises are, which I will repeat here: > > "Not clear what you mean by that. Do you mean you ASSUME FROM THE START > that if two twins have the same proper acceleration as a function of proper > time, then identical values of the proper acceleration are "simultaneous" > in some absolute sense? (so for example, if the twins initially accelerate > to build up speed in opposite directions, then coast for a while, then > accelerate to turn around and eventually reunite, you'd be assuming that > the moments that each one began to accelerate to turn around after the > coasting phase would be simultaneous in absolute terms)" > > Please tell me, yes or no, if you ASSUME FROM THE START the premise above > about identical proper accelerations being simultaneous in "real and > actual", i.e. absolute, terms. And if no, please tell me what basic > starting premises you DO start from that allow you to derive this as a > conclusion. > > > > Of course we can VIEW these slowings differently from different frames, > but the ACTUAL effects they produce on the observer who experiences them > are exact. > > > If you assume from the start that identical proper accelerations are > simultaneous in "actual" terms, or that they produce identical "actual" > slowings of clocks, or something of that nature, then you are simply > ASSUMING FROM THE START that p-time works in exactly the way you want it to > work, not "demonstrating this" in any way. > > > > It is these exact actual effects that my method explains, and yours > doesn't. We know these effects are real and actual when twins meet up with > different ages. Thus we know they were ALSO REAL AND ACTUAL BEFORE the > twins met. That is pure simple logic. > > > No it isn't. "Logic" is not just making an assertion and then shouting the > magic word "logic", it involves actually starting from some premises and > showing, by a series of logical deductions, how they lead to the desired > conclusion. > > What's more, you are entirely vague on what you mean by "effects". This > was another question from my last post that you ignored--you had said of > proper accelerations, "There is no doubt these are real actual CAUSES with > specific measurable values that thus must have real actual EFFECTS with > specific actual values. So you are now saying 'that all frames DO preserve > these effects'?" In response, I asked you: > > 'What "EFFECTS" do you think they cause? Can you name a SPECIFIC effect on > a SPECIFIC variable used in relativity? As I've told you before, if you are > talking about some notion of a "change in clock rate", then in relativity > there is no frame-independent way to assign a "specific actual value" to > the concept of a "clock rate", the clock rate can only be defined relative > to a particular coordinate system, so the "clock rate" at a particular > event on the clock's worldline can have DIFFERENT values depending on what > coordinate system you use. So, if this is in fact what you mean by > "effects", then I would DENY that proper accelerations "have real actual > EFFECTS with specific actual values". If you mean something else by "real > actual EFFECTS", you'll have to name the specific effect or your argument > will be hopelessly vague.' > > You gave no answer, as usual--you like to keep things nice and vague so > that you can keep playing the rhetorical game of slipping between different > meanings of the same phrases, apparently. > > > > > How many times do I have to explain. The twins exchange flight plans for > EXACT SAME ACCLERATIONS AT THE EXACT SAME TIMES before they part. > > > OK, I assume you mean exact same PROPER times, not coordinate times? > > > This ABSOLUTELY ENSURES that their age rates will slow EXACTLY THE SAME > during their trip. There is no way around that. > > > There is a way around that, it's called "relativity". There are plenty of > frames that say that their "exact same accelerations" happened at the same > proper time but different coordinate times, and these frames don't agree > that "their age rates will slow EXACTLY THE SAME during their trip." All > these frames are considered equally valid in relativity, as demonstrated by > the quotes from physicists I provided earlier. > > > > > Another observer can VIEW that differently but from the POV of the twins > themselves it IS EXACT AND ABSOLUTE. > > > > The twins don't have any natural "POV" about how their "age rates slow", > there is no way for them to measure this directly (like they can measure > proper time or proper acceleration, with a simple physical instrument) > without making some specific CHOICE of what frame to use. > > > > Thus it is clear to anyone that to properly analyze the REAL ACTUAL > CORRELATION OF THE TWINS' AGES WE MUST PRESERVE THE REAL ACTUAL > RELATIONSHIP OF THE ACCELERATIONS THAT ARE THE ONLY CAUSE OF AGE RATE > CHANGES. > > > What does "real actual relationship of the accelerations" mean? Again, are > you simply ASSUMING FROM THE START that if they have the same proper > acceleration as a function of proper time, this means that the same values > of proper accelerations must also be simultaneous in absolute terms? If so, > this isn't an assumption that's part of relativity, nor is it one that can > be verified by any coordinate-independent measurement, it's just an > assumption you're pulling out of your ass because you find it aesthetically > appealing. You've given no rational justification that should lead > anyone--whether a block time advocate or a presentist--to agree with you. > > > > > Jeez, how difficult is that to understand? And your different frame to > exchange flight plans in is an oxymoron because it would make their actual > symmetric flight plans appear to be NON symmetric. Only a pair of idiots > would do that.... > > > There'd be nothing idiotic about it in practical terms, since it would > allow them to achieve exactly the same physical paths with the same proper > acceleration as a function of proper time. And once again, you seem to be > using "actual" as a code word for "something I simply assume is true about > how 'actual' simultaneity works from the start, without any rational > justification". > > > > > > You are just endlessly repeating what you read in some relativity textbook > without using simple logic to determine its proper application.... > > > Logic = premise -> logical deductions -> conclusion, you haven't clearly > stated your premises or listed the series of logical deductions that lead > from your premises to your conclusions. > > Jesse > > > > > > > > > > On Monday, March 3, 2014 5:51:25 PM UTC-5, jessem wrote: > > > > On Mon, Mar 3, 2014 at 3:45 PM, Edgar L. Owen <edga...@att.net> wrote: > > Jesse, > > No, it was you that said there was NO correlation. > > > Jeez Edgar, you really need to work on your reading comprehension. I just > got through AGREEING that I had said that there wasn't a correlation, but I > explained that this was because I was using "correlation" in the way YOU > had consistently been using it up until now, to refer to a 1:1 correlation > in which each proper age of a twin is matched up to one unique proper age > of the other twin. The archive at http://www.mail-archive. > com/everything-list@googlegroups.com/ has a better search function than > google's archive (returning individual posts rather than threads), so I > searched for posts from Edgar L. Owen with "correlate" or "correlation" in > them, results here: > > ... -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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