Jesse, Forget about coordinate systems, that isn't really the issue.
The point is that each twin has A REAL ACTUAL AGE at every point on its world line no matter what its relativistic circumstances. The point is that it is always possible for each twin to figure out a 1:1 correlation of the real actual ages of each other, and both twins will AGREE to that correlation. They can't OBSERVE the real actual age of the other twin in some cases, but they can always use their knowledge of relativity and logic to figure out what it is. Edgar On Wednesday, February 26, 2014 5:44:33 PM UTC-5, jessem wrote: > > > On Wed, Feb 26, 2014 at 4:50 PM, Edgar L. Owen <[email protected]<javascript:> > > wrote: > > Jesse, > > A symmetric trip is defined in terms of the symmetric view of two > observers A and B OF EACH OTHER IN TERMS OF THEIR OWN COMOVING COORDINATE > SYSTEMS. > > > If they aren't inertial observers in flat spacetime--and they can't be > inertial if they depart from one another and then reunite later--then > "their own comoving coordinate systems" is a COMPLETELY UNDEFINED PHRASE. > There are an infinite number of DIFFERENT non-inertial coordinate systems > you could design in which they remain fixed at the spatial origin of the > coordinate system (so each one is "comoving" in that sense), and there is > no convention recognized by physicists that "their own comoving coordinate > system" would refer to any particular one of these different possible > systems. DO YOU DISAGREE? > > I have asked variants of this question several times now, once again you > seem to be back to your old habit of refusing to answer simple > agree/disagree questions I ask you, even after you have demanded that I > answer a number of yours. As I said before, this is quite rude behavior, > and if you aren't interested in civil reasoned discourse where you actually > address the other person's arguments and questions, rather than just > haranguing them with the same assertions and expressing incredulity that > they could fail to be convinced, then there's obviously no point to any > further exchanges between us. > > > The proper times of both twins A and B have a 1:1 correlation and are > equal at start and finish of the trip. > > > Although it's true in a frame-independent sense that their proper times > are equal at the end when they reunite, any 1:1 correlation of proper times > DURING the trip can only be defined relative to a particular coordinate > system, and there's no physical reason why using the system where their > velocities are symmetrical is more "correct" than using any other > coordinate system. As I just said in my last post: > > 'It isn't a 1:1 correlation between the proper times of A and B without > qualification, it's a 1:1 correlation between the proper times of A and B > RELATIVE TO THEIR REST FRAME. If you use a different frame, there is a > different 1:1 correlation between the proper times of A and B, RELATIVE TO > THAT OTHER FRAME. Nothing in the phrase "1:1 correlation between the proper > times of A and B" by itself tells us what frame to use.' > > Do you disagree with the above? > > > > PROPER clocks always run at the same rate in the same relativistic > conditions. > > > "Run at the same rate" has no coordinate-independent meaning in > relativity. You won't find any relativity textbook that defines the "rate" > of a clock in any way except relative to a particular choice of coordinate > system (assuming we're not just talking about visual rates based on light > signals). > > Do you disagree that the above is true ACCORDING TO MAINSTREAM RELATIVITY > THEORY AS UNDERSTOOD BY PHYSICISTS? (if you agree, but you think that YOU > have discovered a new coordinate-independent concept of "clock rate" that > physicists have failed to recognize, then please specify that). > > > > The laws of nature do not change during the trip. The relativistic > conditions of both PROPER clocks thus DO run at the same rates DURING the > trip. Forget everything else but the PROPER clocks because it's irrelevant > to the case. > > > "Proper time" deals only with clock readings at specific locally-defined > events on their worldlines (like the time on their clock at the moment they > pass next to some marker in space), there is no corresponding notion of a > coordinate-independent "proper rate" of a clock. Again, the "rate" a clock > is ticking is an INHERENTLY coordinate-dependent notion in mainstream > relativity theory. > > > > > Thus there will be a 1:1 correspondence of PROPER clock times DURING THE > TRIP. > > This is NOT any SINGLE FRAME VIEW. You continue to try to analyze it from > some single frame. IT CAN'T BE DONE. This is a logical consequence of the > laws of relativity, NOT THE VIEW FROM ANY SINGLE FRAME. > > > > You say "logical consequence", but again it is just an assertion, not an > actual logical demonstration of HOW the laws of relativity lead to this > conclusion. > > > > If > > ... -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
