On Tue, Feb 11, 2014 at 9:45 AM, Edgar L. Owen <[email protected]> wrote:
> Jesse, > > I agree that Individual relativistic equations from a particular > coordinate system don't support p-time simultaneity but comparing both > equations of the two coordinate systems in the system, e.g. twin A and twin > B, relativity clearly DOES imply a notion of p-time simultaneity because it > does allow a 1:1 relationship between the comoving clock times in their own > frames of A and B. > You mean even if twins A and B are in relative notion you think "comparing both equations of the two coordinate systems ... does allow a 1:1 relationship between the comoving clock times in their own frame of A and B"? If so, I have no idea what you mean. Say twin B and twin A start moving away from each other with a relative speed of 0.6c at birth, so in each one's rest frame the other one's clock is running slow by a factor of 0.8. Then in twin A's inertial rest frame, the event of A turning 50 is simultaneous with twin B turning 40, but in B's inertial rest frame, the event of B turning 40 is simultaneous with A turning 32. So what is the "1:1 relationship" here, and what event on A's worldline does it pair with the event of B turning 40? Jesse On Sunday, February 9, 2014 9:27:38 PM UTC-5, jessem wrote: > > > > On Sun, Feb 9, 2014 at 4:01 PM, Edgar L. Owen <[email protected]> wrote: > > Jesse, > > Both, but you completely ignored my broad conceptual argument I gave first > thing this morning of why relativity itself assumes an unstated present > moment background to all relativistic relationships. > > > You mean the post at https://groups.google.com/ > d/msg/everything-list/jFX-wTm_E_Q/mHoddIqTX7kJ ? But I didn't ignore it > at all, I responded to it at https://groups.google.com/ > d/msg/everything-list/jFX-wTm_E_Q/yDwctm892xMJ by pointing out some > crucial parts early on I disagreed with, on which the entire argument after > that seemed to rest. In particular, "relativistic calculations" do not > support the idea of a unique 1:1 relationship between clock times, since > different frames give *different* relationships between clock times and > clock rates, and all frames are considered equally valid. Of course I > realize that p-time *postulates* such a unique 1:1 relationship, but you > seemed to say relativistic calculations themselves provided one, which just > isn't true. > > > Sorry, but I disagree on your second point. P-time simultaneity does NOT > have purely spatial analogues. > > > I never asserted p-time simultaneity had spatial analogues. My point was > that for any argument you made to try to *establish* the need for p-time > using quantitative observations about the twin paradox (as opposed to just > assuming p-time as a given), I could point to a spatial analogue. > > If you weren't interested in trying to provide a demonstration to convince > others that block time is flawed and that p-time is needed, but were merely > talking about what would be true *if* p-time existed, then I wouldn't > bother bringing up spatial analogues. But it seems to me you are indeed > trying to make an argument for it, not just assume it, so they are quite > relevant to that. > > So, the question remains: do you think there are any quantitative aspects > of the twin paradox scenario (involving clock times, coordinate times, > relativistic equations, etc.) which DO NOT have direct spatial analogues in > the measuring tape scenario? If so what are they? > > Jesse > > > > > Clock time does, at least in your weak sense..... I did explain that at > length more than once... > > Edgar > > > > On Sunday, February 9, 2014 3:29:39 PM UTC-5, jessem wrote: > > > > On Sun, Feb 9, 2014 at 2:53 PM, Edgar L. Owen <[email protected]> wrote: > > Jesse, > > The crux of my answer to the crossed tapes question was that yes that > would be true of clock time but not for p-time. Again you are using the > question to argue against clock time simultaneity. And I agree with that > 100%. It's just not p-time... > > > But weren't you trying to use the twin paradox scenario to make an > *argument* in favor of p-time, rather than just assuming it from the start? > If so, then I'm wondering if the argument just involves pointing to some > broad conceptual understanding of what happens in the twin paradox > scenario, or if you think there are specific numerical facts that don't > have any good interpretation under a purely "geometric" understanding of > spacetime (like the fact that they can be at the "same point in spacetime" > but have elapsed different ages since their previous meeting). If it's the > latter, then it's reasonable to point out that these numerical facts have > exact analogues in purely geometric facts about the measuring tapes (like > the fact that the tapes can cross at the "same point in space" but have > elapsed different tape-measure distances since their previous crossing). > > Jesse > > > > > > Edgar > > > > On Sunday, February 9, 2014 2:22:20 PM UTC-5, jessem wrote: > > > > On Sun, Feb 9, 2014 at 1:21 PM, Edgar L. Owen <[email protected]> wrote: > > Jesse, > > It's not clear to me what you mean by, "in every coordinate system the > time-coordinate of A = the time-coordinate of B. Are you actually > disagreeing with that (please answer clearly yes or no)". > > The way I understand that the answer is clearly NO. The whole idea of > relativity is that the time coordinates (clock times) of A and B are NOT in > general the same in either A nor B's coordinate systems, or any other > coordinate system. > > > I think I see where you are confused--the term "time coordinate" does NOT > in general mean the same thing as "clock times" in relativity, it only does > if the clock in question is a coordinate clock (part of a ruler/clock > system as I described), or happens to agree exactly with a coordinate clock > at the same point in spacetime. The time on a clock which isn't a > coordinate clock is referred to as a "proper time" for that clock, not a > "time coordinate". So with that clarification on the terminology used by > physicists, would you agree with my quoted statement above? > > > > And I did answer your crossing tapes example in detail showing how it is > not relevant for p-time. I'm beginning to wonder if you actual read my > posts... > > > I asked for an answer to the specific question of whether there is any > quantitative feature of the twin paradox scenario that doesn't have a > quantitative analogue in the measuring tape scenario. Before the most > recent post of yours that I was responding to when I asked this question, > the only earlier posts of yours I can remember directly responding to the > issue of spatial analogies are the ones http://www.mail-archive.com/ev > [email protected]/msg48047.html and > http://www.mail-archive.com/[email protected]/msg48049.html, > but both of them featured variation on the broad conceptual objection > that any spatial situation like cars on a road or wires in ice must > themselves exist in time, but I addressed this issue in my own post at > http://www.mail-archive.com/[email protected]/msg48058.htmlpointing > out that we could restr > > ... -- 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. 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