On Sun, Feb 23, 2014 at 11:57 AM, Edgar L. Owen <[email protected]> wrote:
> Jesse, > > To address your question. I'll start with your terminology. Your A>B>C > doesn't follow and I'll show why it doesn't. > > "Same space and time coordinates"? In which coordinate system? In general > these will be different in different coordinate systems, and as you > yourself have pointed out choice of coordinate system is arbitrary in > relativity. > > So if twins A and B happen to have the same clock time coordinates at the > same point in space they could well be at that point in space in entirely > different p-times OR they could be there at the same P-time. That depends > on their relativistic history and choice of coordinate systems. > > Let me clarify. Take a point Px,y,z in space. One twin could pass through > that point at earth time 1989 when his proper clock (actual age) was 30, > and then ten years later in 1999 the other twin could pass through that > point P when his proper clock (actual age) was 30. In this case they would > NOT be at the same point in p-time even though 10 years apart they DID have > the exact same "space and time coordinates". > You are repeating a confusion which I have already corrected several times in the past. In relativity, the "time coordinate" of an event is defined ONLY in terms of a set of "coordinate clocks" which are affixed to particular position coordinates, like the clocks attached to different markings on a lattice of rigid rulers that are used to define coordinate time in inertial reference frames, as illustrated here (please take the time to click the link and at least glance at the illustration): http://www.upscale.utoronto.ca/GeneralInterest/Harrison/SpecRel/SpecRel.html#Exploring If the clocks of your twins aren't coordinate clocks--as implied by the fact that they are said to "pass through" a given set of spatial coordinates, rather than being permanently attached to them--then those readings ARE NOT TIME COORDINATES in whatever coordinate system you are using to define position coordinates. They are PROPER TIMES for the twins (specifically the proper time between their birth and any other moment on their worldline, if they represent ages), which are DIFFERENT from coordinate times. Of course we could program our coordinate clocks in such a way that the coordinate clock at x,y,z, also showed a reading of 30 years as one of the twins was passing next to it, but in this case it would NOT show a reading of 30 years when the other twin was passing next to it, so the event of that other twin's clock reading 30 would NOT be assigned a coordinate time of 30 in this coordinate system. And the coordinate clock time need not agree with either twin's proper time--for example, the coordinate clocks could just be designed to show the current date (in Greenwich mean time, say), in which case the event of the first twin having a PROPER time of 30 would have a COORDINATE time of 1989, and the event of the second twin having a PROPER time of 30 would have a COORDINATE time of 1999. Do you disagree that in relativity the coordinate time of any event in a given coordinate system is defined in terms of local reading on the COORDINATE CLOCK for that system that was right next to the event when it happened, and that it may differ from the time shown on a clock which isn't a coordinate clock for that coordinate system? Yes or no? Do you disagree that GIVEN such a definition of coordinate time, then two events which have the same coordinate position and coordinate time in a single coordinate system will necessarily have the same coordinate position and coordinate time as one another in all other coordinate systems, and they will also have happened at the "same point in spacetime" according to the operational definitions I gave earlier? Yes or no? Jesse > > On Sunday, February 23, 2014 11:11:49 AM UTC-5, jessem wrote: >> >> >> On Sun, Feb 23, 2014 at 8:22 AM, Edgar L. Owen <[email protected]> wrote: >> >>> Hi Jesse, >>> >>> First, my name is Edgar, not Edward.... >>> >>> OK, even though I've answered this question of yours on several >>> occasions, I'm willing to finally put it to bed once and for all. >>> >>> So please state in a non-ambiguous manner exactly what the question is >>> AND what you think the implication of it is. >>> >>> As I understand it your question is there some exact relativistic clock >>> time analogue of two tape measures crossing. Is that correct? And if so, >>> what's the point? What difference does it make in your mind one way or the >>> other? >>> >> >> Clear evidence that you are not even bothering to follow the links when I >> link back to an earlier post and ask you to address a question. The tape >> measure analogy is another issue you haven't responded to when I asked you >> about it, and I would eventually like to discuss that as well, but the >> question I was asking about here had nothing to do with tape measures or >> geometric analogies, I stated several times that it was the question in the >> last two paragraphs of my post at https://groups.google.com/ >> d/msg/everything-list/jFX-wTm_E_Q/LF0Xcds_qtQJ which begins with "If we >> have some coordinate system where relativity predicts the event of Alice's >> clock reading 30 happens at exactly the same space and time coordinates as >> the event of Bob's clock reading 40 ... ". This question deals with the >> issue of whether two events that have the same space and time coordinates >> in some coordinate system are guaranteed in relativity to satisfy the >> operational definition of "same point in spacetime" that I had provided >> earlier. If I can get you to see that "same space and time coordinates >> ->implies-> same point in spacetime defined operationally ->implies-> same >> moment in p-time", then we can go back to discussing the >> Alice/Bob/Arlene/Bart example that I think shows a basic contradiction in >> your claims about how p-time simultaneity works, since your only response >> when I asked you to address that example was to deny that events at the >> same point in spacetime necessarily occur at the same p-time. So I'd like >> to prioritize this for now and we can get back to the measuring tapes >> later, and meanwhile I'll respond to your own questions if you are willing >> to respond on this subject in parallel. >> >> Jesse >> >> >>> >>> >>> On Saturday, February 22, 2014 9:17:45 PM UTC-5, jessem wrote: >>>> >>>> >>>> >>>> On Sat, Feb 22, 2014 at 7:40 PM, Edgar L. Owen <[email protected]> wrote: >>>> >>>>> Jesse, >>>>> >>>>> 1. Do you agree you are actually a particular age right now today as >>>>> you read this? >>>>> >>>> >>>> Hey, more questions! But as usual, I see you demand that I answer your >>>> questions while you pointedly ignore the question I have repeatedly asked >>>> you about the meaning of "same point in spacetime", even after I put the >>>> question into a form that only requires a simple "agree/disagree" type >>>> answer--again see the last two paragraphs of >>>> https://groups.google.com/d/msg/everything-list/jFX-wTm_E_Q/ >>>> LF0Xcds_qtQJ . Sorry Edward, but this is really rude behavior, adults >>>> having a civil discussion understand that they are each expected to make >>>> some effort to address the other's questions and arguments, you can't >>>> expect to have the unique power to dictate what will be discussed >>>> (especially when the line of discussion you are so stubbornly ignoring is >>>> one stemming from an argument of mine that I think shows a basic >>>> mathematical contradiction in your ideas about p-time simultaneity). I will >>>> be happy to answer all your questions and arguments in detail, just as I >>>> have always done in the past, if you are willing to address my question in >>>> some way--even if it's not a simple agree/disagree answer, but something >>>> else like saying that you find the question unclear and in need of >>>> clarification. But if you outright refuse to talk about anything but your >>>> own preferred lines of argument, then I'll take that as a sign that you are >>>> unwilling to show any basic respect to others who disagree with you, and >>>> that you are only interested in lecturing about your ideas rather than >>>> engaging in two-way conversation, in which case there'd be no point in my >>>> responding to your posts any further. >>>> >>>> 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. >>> >> >> -- > 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. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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