On Tue, Feb 11, 2014 at 9:55 AM, Edgar L. Owen <edgaro...@att.net> wrote:
> Jesse, > > If you don't agree with anything I've said, with any of the answers I've > provided to your numerous questions, then I have to assume your motive is > asking all these questions is not to learn anything about the theory (since > you say your mind is already made up and you believe in block time) but > presumably just to try to uncover any contradictions that would falsify the > theory? > No, it's mainly been to show that your own attempts to uncover contradictions that falsify block time--like the idea that the notion of the twins meeting "at the same point in spacetime" with different clock times requires some new idea of time that block time can't account for--don't actually succeed in doing so. This has been the point of my spatial analogies, to show that any such argument you could make involving quantitative facts about the twin paradox would have a directly analogous argument involving quantitative facts about the measuring tape, yet you wouldn't agree that there is any new idea of "same point in y" needed there, I believe you think ordinary geometry can handle spatial facts about the measuring tape just fine. On that subject, you still haven't answered my question about whether you think there are any particular quantitative facts about the twin paradox that you would make use of in such arguments that *don't* have direct spatial analogies. Another thing I have been doing in my discussions with you was to try to show that p-time would have to be purely "metaphysical" in the sense that there'd be no empirical procedure for deciding whether events were simultaneous in p-time, but that isn't the same as falsifying it, I don't think there's anything logically wrong with adopting presentism as a metaphysical "interpretation" of relativity theory, even though I don't do so myself. > > Well, that's fine, and a useful exercise, but apparently after all this > discussion you haven't been able to do that so far. Is that correct? > In fact I think I may have found a contradiction in your statements that A) there's a unique objective truth about whether two events are simultaneous in p-time, B) this truth is transitive, and C) if two objects are at rest relative to each other, readings on their clocks that are simultaneous in their inertial rest frame are simultaneous in p-time. Can you please consider the scenario I described in the post at https://groups.google.com/d/msg/everything-list/jFX-wTm_E_Q/pxg0VAAHJRQJwith the two pairs of twins, and tell me if you disagree with any of the individual numbered statements 1-4 about which events must be simultaneous in p-time according to your rules? If I have found a contradiction of course this doesn't disprove the very idea of p-time, but it would probably imply that you have to drop assumption C), which I think would leave you without any rule for empirically deciding which events are simultaneous in p-time, supporting my point that this can only be a purely "metaphysical" notion. > And you say if by agree we just mean taking my assumptions you COULD tell > me if you agreed or not. But in fact you have never to my recollection said > you agreed with anything even given those assumptions. So given those > assumptions what DO you agree with? > You've never asked me to adopt some assumptions I don't actually believe in and tell me what they would imply, that isn't a common thing to do in a discussion like this (you haven't done it with block time assumptions either). And "given those assumptions what DO you agree with" is a very broad question, could you narrow it down by mentioning the specific assumptions I should adopt (for example, whether they would only include assumptions A and B above or whether they should also include C even though I think this leads to conclusions that contradict presentism), and specific ideas you want to know if I agree or disagree with given these assumptions? Jesse > Why is this could not a WOULD? > > Edgar > > > On Sunday, February 9, 2014 9:46:14 PM UTC-5, jessem wrote: >> >> >> >> On Sun, Feb 9, 2014 at 7:08 PM, Edgar L. Owen <edga...@att.net> wrote: >> >> Jesse, >> >> Before I go the trouble of answering your 4 questions on your example >> could you please tell me if you agree with the 3 examples I provided, and >> the p-time simultaneities I stated there? >> >> >> What do you mean "agree with"? I don't even agree there is any such thing >> as an objective frame-independent truth about simultaneity, I think block >> time is quite satisfactory. And if there was an objective simultaneity, >> which you would call simultaneity in p-time, I would see no reason to think >> it should obey the postulates you suggest, like the postulate that for two >> clocks at rest relative to one another, simultaneous readings in their rest >> frame should automatically be simultaneous in p-time. >> >> Are you just asking me to consider the hypothetical that *if* there was >> such a thing as objective p-time simultaneity, and *if* it respected the >> postulates you believe in, would I *then* agree with your analysis of >> various examples? If that's all you're asking I can tell you if I agree >> with your analysis of various examples given these hypotheticals. But if >> you are asking me to agree or disagree on anything more than that, then my >> answer is "no, I don't agree with your statements about p-time because I >> don't believe in your basic premises." >> >> >> >> >> I gave simpler examples to make p-time simultaneity easier to understand, >> so it makes no sense to address your slightly more complex examples until >> we agree on my 3. >> >> Also in general it would be useful if you could let me know what you do >> agree with that I say about p-time. Your MO is just to continually ask >> question after question without usually indicating what answers of mine you >> agree with or don't. To conduct an objective discussion it helps to know >> what we agree with as well as what we don't. Don't you agree? >> >> >> Sure, but I thought you understood that I was an advocate of block time, >> so that it would go without saying that I wouldn't agree with any >> statements that presupposed p-time. None of the statements I ask you to >> agree or disagree with presuppose block time, they are either questions >> about your own beliefs about p-time, or questions about your use of >> examples from relativity theory to make arguments for a need for p-time. >> >> Jesse >> >> >> >> >> >> On Sunday, February 9, 2014 5:45:07 PM UTC-5, jessem wrote: >> >> >> >> >> On Sun, Feb 9, 2014 at 3:57 PM, Edgar L. Owen <edga...@att.net> wrote: >> >> Jesse, >> >> My answer to your last paragraph is yes, as I understand it... >> >> For transitivity ignore my first post on that, and just read the second >> that concludes there IS transitivity.. >> >> Edgar >> >> >> >> OK, then in the scenario I described, please tell me if you disagree with >> any of the conclusions 1-4 about which events are simultaneous in p-time: >> >> Start by considering their initial positions, velocities and clock times >> in a coordinate system where Alice and Bob are at rest. At coordinate time >> t=0 in this frame, Alice is at position x=0 light-years, Bob is at position >> x=25 light years, and their clock readings are T(Alice)=0 years, T(Bob)=0 >> years. Meanwhile at the same coordinate time t=0, Arlene is at position x=0 >> light years--her position coincides with that of Alice--and her clock reads >> T(Arlene)=0 years, and Bart is at position x=9 light years and his clock >> reads T(Bart)=-12 years. In this frame, Arlene and Bart are both moving in >> the +x direction at 0.8c. So 20 years later in this frame, they both will >> have moved forward by 20*0.8=16 light-years, so at t=20 Arlene is at >> position x=16 light-years while Bart is at position x=25 light years. Their >> clocks are running slow by a factor of 0.6 in this frame, so in a span of >> 20 years they tick forward by 12 years, meaning at t=20 Arelene's clock >> reads T(Arlene)=12 years and Bart's clock reads T(Bart)=0 years, so this >> event on Bart's worldline is simultaneous in his own frame with the event >> on Arlene's worldline where her clock read T(Arlene)=0 years and her >> position coincided with that of Alice (the fact that these events are >> simultaneous in the Arlene/Bart rest frame is easily proven using the >> Lorentz transformation, I can supply the details if needed). But since Bart >> is at x=25 light years at this moment, his position coincides with that of >> Bob who has remained at rest at x=25 light years, and whose clock is >> keeping pace with coordinate time so his clock reads T(Bob)=20 years. >> >> Summing it all up, if we use BOTH the rule that a pair of clocks at rest >> relative to one another and sychronized in their rest frame must also be >> synchronized in p-time, AND the rule that events which coincide at the same >> point in spacetime must happen at the same p-time, we get the following >> conclusions: >> >> 1. The event of Bob's clock reading T(Bob)=0 and the event of Alice's >> clock reading T(Alice)=0 must be simultaneous in p-time, since they are >> simultaneous in the Alice/Bob rest frame. >> >> 2. The event of Alice's clock reading T(Alice)=0 and the event of >> Arlene's clock reading T(Arlene)=0 must be simultaneous in p-time, since >> they happen at the same point in spacetime. >> >> 3. The event of Arlene's clock reading T(Arlene)=0 and the event of >> Bart's clock reading T(Bart)=0 must be simultaneous in p-time, since they >> are simultaneous in the Arlene/Bart rest frame. >> >> 4. The event of Bart's clock reading T(Bart)=0 and the event of Bob's >> clock reading T(Bob)=20 years must be simultaneous in p-time, since they >> happen at the same point in spacetime. >> >> >> >> >> >> >> >> On Sunday, February 9, 2014 3:22:28 PM UTC-5, jessem wrote: >> >> >> >> On Sun, Feb 9, 2014 at 3:02 PM, Edgar L. Owen <edga...@att.net> wrote: >> >> Jesse, >> >> 1. is correct. There is an objective truth that past events are >> simultaneous in p-time. Recall I also gave the exact same answer yesterday >> or the day before. >> >> >> Thanks. So how about the issue of transitivity? If event A and event B >> were objectively simultaneous in p-time, and event B and event C were >> simultaneous in p-time, does this necessarily imply A and C were >> simultaneous in p-time, or not? >> >> >> >> >> It will always be able to determine what clock time t in one frame >> occurred at the same p-time of any t' in another frame, but the actual >> values of those t's and t''s will depend on the conditions in the preceding >> paragraph, on the choice of frames. Which is what I said at least several >> separate times in the preceding days. >> >> >> By "clock time" you mean the actual physical reading on a clock, not any >> other notion of coordinate time, right? Say one event is clock 1 reading >> t=50 seconds, and another event is clock 2 reading t=30 seconds. These >> events either ARE or AREN'T objectively simultaneous, correct? There can't >> actually be different, equally valid answers to that question that depend >> on one's "choice of frames", so when you say it will "depend on the >> conditions in the preceding paragraph, on the choice of frames", do you >> just mean that there are rules that tell us the objective truth about >> p-time simultaneity should match some PARTICULAR frame's definition of >> simultaneity, but that the particular frame that must be used depends on >> the physical details of the objects involved, like whether the two clocks >> are at rest relative to one another (in which case the rules say you *must* >> use their rest frame's definition of simultaneity to determine p-time >> simultaneity, you don't have any "choice" in the matter). 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