On Sat, Mar 1, 2014 at 5:35 PM, Edgar L. Owen <[email protected]> wrote:
> Jesse, > > Let me ask you one simple question. > > In the symmetric case where the twins part and then meet up again with the > exact same real actual ages isn't it completely logical to conclude they > must also have been the exact same real actual ages all during the trip? > > If, as you claim, the same exact proper accelerations do NOT result in the > exact same actual ages all during the trip then how in hell can the twins > actually have the exact same actual ages when they meet up? > It's not that I'm claiming that there's an objective truth that they DON'T have the same ages during the trip. I'm just saying that as far as physics is concerned, there simply IS NO OBJECTIVE OR "ACTUAL" TRUTH ABOUT SIMULTANEITY, and thus there is neither an "actual" truth that they are the same age or an "actual" truth that they are different ages. These things are purely a matter of human coordinate conventions, like the question of which pairs of points on different measuring-tapes have the "same y coordinates" in any given Cartesian coordinate system. Similarly, questions of simultaneity reduce to questions about which pairs of points on different worldlines have the "same t coordinate" in any given inertial coordinate system, nothing more. > > What is the mysterious mechanism you propose that causes twins that do not > have the same actual ages during the trip to just happen to end up with the > exact same actual ages when they meet? > Again, I do not say there is any objective truth that they "do not have the same actual ages", I simply say there is no objective truth about which ages are "actually" simultaneous in some sense that is more than just an arbitrary coordinate convention. But if you're just asking about how things work in FRAMES where they don't have the same actual ages during the trip, the answer is that in such a frame you always find that the answer to which twin's clock is ticking faster changes at some point during the trip, so the twin whose clock was formerly ticking faster is now ticking slower after a certain time coordinate t, and it always balances out exactly so that their clocks have elapsed the same total time when they reunite. If you like I could give you a simple numerical example where I analyze a symmetric trip both from the frame where their velocities are symmetrical, and a different frame where their velocities are non-symmetrical, and show that it does work out that the second frame predicts their ages will be the same when they reunite despite them aging at different rates during different phases of the trip in this frame. Meanwhile, are you going to address the question about whether you agree with the 3 premises that I claim together lead to a contradiction? I'll repost the question from my last post: 'Again, the 3 premises are: 1. If a pair of inertial observers are at rest relative to one another, then events (like clock readings) that are simultaneous in their comoving frame are also simultaneous in p-time 2. Any two events that happen at precisely the same position and time coordinate in a particular inertial frame must be simultaneous in p-time 3. p-time simultaneity is transitive So to start with, please just tell me if you do agree with all these premises, or if there is one or more you disagree with or aren't sure about and require clarification on. And if you disagree with or are not sure about #2, this is the "same point in spacetime" issue we had been discussing earlier before you stopped responding, so in this case please go back to my last post on the subject at https://groups.google.com/d/msg/everything-list/jFX-wTm_E_Q/dM2tcGYspfMJand respond to that.' Jesse -- 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.
