On Wed, Feb 26, 2014 at 4:50 PM, Edgar L. Owen <edgaro...@att.net> 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 can't even get this simple fact I see no reason to proceed. It > seems to me that your stated agenda of not accepting p-time prevents you > from thinking objectively here. > No mainstream physicist would agree with this "simple fact", and that has nothing to do with whether they prefer block time or presentism or have no opinion on the matter. They all recognize that clock rates, and "correspondences" between proper times of clocks separated in space, are inherently frame-dependent. In any case, a simple way to proceed would involve just doing me the courtesy of answering my questions, so we can better pinpoint the first point on which we are in disagreement, and see if this is a matter of disagreeing about how things work in mainstream relativity theory (in which case I can look for references to support my claims, and we could also ask Brent to weigh in since he's a physicist), or if it's a matter of you asserting something that you acknowledge differs from mainstream relativity. Also, as I said before, I claim that I have ALREADY found an example which demonstrates a contradiction in your claims about p-time simultaneity, and your initial response was just to disagree with the premise I made use of that events at the same point in spacetime must have happened at the same p-time, but as I said (and was already halfway to demonstrating), if you correctly understood what I meant by "same point in spacetime" you wouldn't actually disagree with this premise after all. So if you will simply address the questions which I asked you at https://groups.google.com/d/msg/everything-list/jFX-wTm_E_Q/dM2tcGYspfMJ(which you promised you would get to earlier, saying "I'll also address your latest questions in separate replies.......") then once we can come to an agreement about the meaning of "same point in spacetime" we can go back to that initial example with Alice/Bob/Arlene/Bart, and see if you can find a reason to disagree with any of the specific assertions I made about it. Or is your response to a claimed disproof of your theory going to be to ignore it and hope it goes away? Jesse > > > On Wednesday, February 26, 2014 3:40:36 PM UTC-5, jessem wrote: >> >> >> >> On Wed, Feb 26, 2014 at 2:31 PM, Edgar L. Owen <edga...@att.net> wrote: >> >> Jesse, >> >> You continue to quibble over terminology to avoid engaging the real >> issues. Of course by 'view' I DO mean the actual equations in terms of a >> coordinate system with origin at a particular observer. There is OF COURSE >> a single set of equations that describes that view. >> >> >> There are a single set of equations for any particular coordinate system, >> but my point is that for non-inertial observers or observers in curved >> spacetime, talking about an observer's "view" is ill-defined because there >> is no convention about which coordinate system to label as the "view" of a >> given observer. Even if you specify that you want a "coordinate system with >> origin at a particular observer", there are an infinite number of DIFFERENT >> non-inertial coordinate systems you could come up with that would have the >> property that the observer is always at the origin, each with a different >> set of equations. I asked about this issue specifically in the second >> question from my last post, which you didn't answer: >> >> '--If you don't disagree with the statement above, do you disagree with >> my statement that there's no specific coordinate system that is understood >> by physicists to represent a particular observer's "view" or "perspective" >> in general relativity, so that if you just talk about equations "used by" >> observer A without specifying a coordinate system, physicists wouldn't know >> what you were talking about?' >> >> Could you please just just quote my questions and answer them >> specifically in turn, as I always do with yours, rather than just sort of >> summarizing what you think my main points are and addressing them in a >> broad manner? >> >> >> Answers to your next question: >> >> Yes, of course the OBSERVABLES are based on some coordinate system, but >> you can't seem to get it through your head that any observer A who observes >> another observer B can also know the equations governing how that observer >> B observes A himself. >> >> >> I'm not sure which question you are responding to here, you say "next >> question" but it seems like this is actually a response to my FIRST >> question (with no response given to any of the others), namely: >> >> '--Do you disagree that equations that observer A uses to "calculate the >> observables of any other observer B" are always based on A using some >> particular coordinate system? (if so, can you give an example of an >> equation that could be used to make such a calculation which would not >> depend on any specific coordinate system, but which would still be >> observer-dependent in some sense, so it would still be meaningful to >> identify this equation specifically with observer A?) ' >> >> You didn't really respond to any of the subsequent three questions with >> dashes before them, as far as I can see, although you did respond to the >> question in my last paragraph. Can you please go back and respond to the >> middle 3 questions? >> >> >> >> Do you deny that? >> >> >> I deny that there is any single set of "equations governing how observer >> B observes A himself", if B is not an inertial observer in flat spacetime. >> If he's not, then as I said, there's no convention in relativity that says >> that any particular coordinate system should be interpreted as "belonging" >> to B. If you specify in detail what coordinate systems you want A and B to >> use to perform calculations (or if both of them are inertial in flat >> spacetime, so it's taken as read that they each use their own rest frame), >> then of course A can figure out what B would calculate and B could figure >> out what A would calculate. >> >> Also, do you understand that even for inertial observers, the idea that >> an observer's own rest frame can be labeled "his view" or taken to describe >> "his observations" is PURELY A MATTER OF CONVENTION, not something that is >> forced on us by the laws of nature? Physicists just don't want to have to >> write out "in the observer's comoving inertial frame" all the time, so they >> just adopt a linguistic convention that lets them write simpler things like >> "from this observer's perspective" or "in his frame" as a shorthand for the >> observer's comoving inertial frame. Physically there is no reason an >> observer can't assign coordinates to events using rulers and clocks that >> are moving relative to himself though, lots of real-world experiments >> involve measuring-instruments that move relative to the people carrying out >> the experiment. >> >> >> >> >> I'll skip now to the point you make in your last paragraph responding to >> my symmetric trip case: >> >> Your comments here are true (more standard relativit >> >> ... > > -- > 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 everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to firstname.lastname@example.org. > 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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