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. They both experience the exact same amounts of accelerations and gravitation during their trips.
The proper times of both twins A and B have a 1:1 correlation and are equal at start and finish of the trip. PROPER clocks always run at the same rate in the same relativistic conditions. 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. 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. 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. Edgar 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<javascript:> > > 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 everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
