On Sat, Feb 8, 2014 at 10:41 AM, Edgar L. Owen <[email protected]> wrote:
> Jesse, > > No, they do NOT have the same time coordinates in their respective frames > because their clocks read different t-values. > In the post you're responding to here I had another request for clarification which you didn't answer: "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), or are you just pointing out that the shared time-coordinate is different in different systems, or that the shared time-coordinate will not match the clock time for both of them?" Keep in mind that we were talking about what's true according to the definitions of coordinate time in relativity, this question has nothing to do with anything not part of relativity theory like p-time, nor is it asking whether you *approve* of the definitions used in relativity. > You simply cannot invent any frame that makes the actual difference in > their ages go away. > I didn't say anything about making the difference in ages go away. If when they meet twin #1 is turning 30 and twin #2 is turning 40, then if event A = (twin #1 turns 30) and event B = (twin #2 turns 40), in every coordinate system A has the same time-coordinate as B, but they are really different ages at that point. > All you are doing is trying to ignore the effect by assigning a new > arbitrary time to the meeting. That's fine but they are still really > different ages so in that sense they can never actually be at the same > clock time except by an arbitrary definition which ignores the fact of the > trip and thus refuses to address the whole point of the trip. > I have no idea what you think I am "refusing to address". Yes, they really are different ages, I have never suggested otherwise--and they really are those different ages at the same coordinate time as coordinate time is defined in relativity (using local measurements on physical coordinate clocks). You may not *like* that definition of "same time", but if you are actually denying that what I am saying is true ACCORDING TO THE STANDARD DEFINITIONS OF RELATIVITY, then you are misunderstanding something about how relativity works. Speaking of refusing to address things, yet again you just drop the subject of spatial analogues when I explain how every quantitative fact about the twin paradox scenario has a directly analogous quantitative fact in the measuring tape scenario. For example, as I mentioned, the fact that the twins are the same age when they depart is analogous to the fact that at the first crossing-point that the measuring tapes diverge from, they both show the same marking (say, 0 centimeters) at that first crossing point. We can also lay out these tapes on a piece of graph paper with Cartesian coordinate axes drawn on, so that any point on any given tape has a spatial coordinate as well as a measuring-tape marking, analogous to the fact that any event on the twins' worldline has a coordinate time as well as a clock time according to their own clock. I know that in some conceptual way you don't think a spatial scenario can be analogous to one involving time, but can you point out any specific measurable, quantitative facts about the twin scenario that don't have a direct analogue in measurable, quantitative facts in the measuring-tape scenario? As usual this is not meant to be a merely rhetorical question, please answer yes or no (and if "yes" point to a specific measurable quantitative fact in the twin paradox that you think lacks an analogue in the measuring tape scenario). 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.
