On Thu, Jan 2, 2014 at 9:31 PM, LizR <lizj...@gmail.com> wrote: > Jason, > > You may be missing the fact that the acceleration of the space traveller > is what causes the twin paradox. >
I would say it is not so much the acceleration that explains the paradox, but the fact that no matter how you rotate the paths, you always see a kink in the path Pam takes. So even if we start in Pam's reference frame where she is still, she has to stop (putting her back in the reference frame where Sam is 5 (not 1.8), then accelerate to 0.8 c back toward Earth, which she will see as length contracted to 2.4 ly again, and she will experience as taking 3 years, but in this frame, of heading back toward Earth at 0.8 c, Sam is not 5, but 7, so when she gets there after 3 years, Sam is (as she expects) 10 years old. It isn't the acceleration which causes her age to suddenly change, but rather, her changing frames of reference (present moments), that causes her perspective of Sam to radically change, depending on her velocity. > As Edgar pointed out, time dilation is mutual, but only while velocities > are constant. > Their relative velocity in relation to each other, and therefore their relative time dilations and length contractions, are always the same. > Your diagram demonstrated that the straight line parts of Pam's movement > could be mapped either way onto Sam's (just tilt the diagram. But you can't > may the entire trajectory onto Earth time by tilting the diagram. > I'm not sure what you mean by this.. > > Apologies if I'm teaching my gradnmother to suck eggs. > > No worries. Let me know if my example or explanation still does not make sense. :-) Jason > > > On 3 January 2014 15:25, Jason Resch <jasonre...@gmail.com> wrote: > >> >> >> >> On Thu, Jan 2, 2014 at 8:57 PM, Edgar L. Owen <edgaro...@att.net> wrote: >> >>> Jason, >>> >>> An excellent question. First of all let's stick with the actual example >>> of only Sam and Pam. Now how do you know all this stuff about who is doing >>> what when? >>> >> >> I calculate it from the parameters of the experiment as I described it. >> The different answers depend on different reference frames, which you can >> consider as straight lines dividing the past and future (but at different >> angles depending on one's velocity through space). >> >> [image: Inline image 1] >> >> If you consider the gold and purple stars as two different events, the >> person moving to the right sees the present as all events on the blue line, >> and so they see the purple star happen before the yellow star, and vice >> versa for the observer moving to the left, whose present is represented by >> the red line. They see the yellow star come before the purple star. >> >> >>> How are you measuring it to know it's true? >>> >>> >> 4 light years away, at 80% the speed of light. It is no different than >> figuring out how long it takes to travel 4 miles at 0.8 miles per year. >> However, when travelling at these speeds, you have to contend with length >> contraction and time dilation (which are two aspects of the same phenomenon >> seen from two different perspectives). >> >> See: >> http://faraday.physics.utoronto.ca/PVB/Harrison/SpecRel/Flash/LengthContract.html >> for >> a good explanation. >> >> >>> And again the important point to understand is that you MUST disregard >>> SR relative velocity effects which are illusory and non-permanent and >>> vanish when the relative velocities cease when they meet again. >>> >> >> You cannot disregard them. Otherwise you cannot explain why Pam is 6 when >> she meets with Sam at 10. >> >> >>> SR effects are not 'real' in the sense of being absolute. They are >>> transient and relative and equal and opposite for both observers. Both see >>> the other's time slow but that is just measurements, their time is not >>> actually slowing in any absolute permanent sense. By that I mean they are >>> illusions of measurement that exist only during relative motion. So they >>> are not relevant when trying to analyze what is happening in the present >>> moment. >>> >> >> They aren't illusions, from each one's own reference frame, the other is >> going more slowly through time. >> >> >>> >>> GR acceleration affects on the other hand are real and absolute and >>> experienced the same by both observers as the slowing of only the >>> accelerating twin's clock relative to the non-accelerating twin's clock. >>> >> >> Relativity explains clock desynchronization. GR only comes into play when >> gravity is concerned. Pam would still be 6 and Sam 10, even if they >> accelerated instantly, or if Pam was already in motion when they were both >> born. >> >> >>> >>> I think when temporary SR effects are eliminated this problem is >>> resolved and your question is answered... >>> >>> >> It's the SR effects that explain the age differences, and Pam doesn't age >> 4 years when she decelerates. >> >> Jason >> >> >> >>> On Thursday, January 2, 2014 8:39:08 PM UTC-5, Jason wrote: >>> >>>> >>>> >>>> >>>> On Thu, Jan 2, 2014 at 8:07 PM, Edgar L. Owen <edga...@att.net> wrote: >>>> >>>>> Jason, >>>>> >>>>> That's very simple P-time allows us to explain how there is a present >>>>> moment in which we experience our mutual existence, are able to converse >>>>> together, shake hands, and compare our (different) clock times. >>>>> >>>>> If there weren't such a common present moment distinct from our >>>>> different clock times we could do none of those things because we would be >>>>> in different moments of existence. We wouldn't even inhabit the same >>>>> reality. >>>>> >>>>> Obviously that's not a function of being in the same clock time, >>>>> because it happens when we are in different clock times as well.... >>>>> >>>>> >>>> I think it does lead to a problem. Pam and Sam start at the same time, >>>> they are both zero and at Earth. They kiss each other good bye and Pam goes >>>> off into space. The present moment advances and both Pam and Sam experience >>>> something, they are now slightly older and both doing and experiencing >>>> something at this time. >>>> >>>> A little time later, they are both slightly older, and they are both >>>> experiencing something. and so on, and this keeps happening, each of them >>>> experiences one moment after the other. Now, eventually, the event happens >>>> where Pam gets to her destination, Pam is now 3. >>>> >>>> You agreed in an earlier e-mail that Sam is definitely doing something >>>> in this common present P-time when Pam arrives. >>>> >>>> Then a little time later, both are slightly older, and both are >>>> experiencing something. Then Sam turns 2 years old. A little time later, >>>> they are both slightly older, and they are both experiencing something. and >>>> so on, and this keeps happening, each of them experiences one moment after >>>> the other. >>>> >>>> Finally, Pam arrives back on Earth, Sam is 10 and Pam is 6. They shake >>>> hands and hug. >>>> >>>> Notice though that from one P-time to the next, and so on, >>>> continuously, in one P-time Pam was at her destination, and Sam was >>>> definitely doing something, and he was definitely less than 2 years old, >>>> because in a later P-time Sam had his 2nd birthday at the same time Pam was >>>> already on her way back to Earth. >>>> >>>> Yet, in an equally valid perspective (according to relativity) Sam's >>>> 2nd birthday happens before Pam reaches her destination. So if there is a >>>> single P-time, how can the event, Sam's 2nd birthday, happen when Pam is on >>>> her way back AND happen before Pam reaches her destination. If every >>>> P-time is ordered and sequential, this simply isn't possible. You have to >>>> accept that there is more than one consistent way to order the succession >>>> of present moments, which means there is no common present moment everyone >>>> shares. >>>> >>>> You are right that without "some principle X" we wouldn't inhabit the >>>> same reality, but relativity shows that "some principle X" is not, and >>>> cannot be a global, shared, agreed upon succession of present moments. The >>>> "some principle X" is instead, a four-dimensional existence, space-time, >>>> and consistent presents are just "slices" through this space time. If you >>>> envision it in this way, you can perfectly account for all the consistent >>>> views and orderings either Sam, Pam, or Bob might have about which events >>>> happen when, and where, and in what order. >>>> >>>> Jason >>>> >>>> >>>>> >>>>> On Thursday, January 2, 2014 6:05:36 PM UTC-5, Jason wrote: >>>>> >>>>>> >>>>>> >>>>>> >>>>>> On Thu, Jan 2, 2014 at 5:56 PM, Edgar L. Owen <edga...@att.net>wrote: >>>>>> >>>>>>> Jason, >>>>>>> >>>>>>> I said I don't know because SR doesn't know. What's wrong with that? >>>>>>> It's consistent with SR. >>>>>>> >>>>>> >>>>>> Nothing is wrong with that position, I just thought P-time might >>>>>> offer an answer to this problem which exists in SR. >>>>>> >>>>>> >>>>>>> >>>>>>> I don't know WHAT Sam is doing at any particular moment in the >>>>>>> shared present moment, but I know he exists and is doing something. >>>>>>> What's >>>>>>> wrong with that? If I had a mathematical way to determine that I'd >>>>>>> certainly let you know but as far as I know there isn't any. We just >>>>>>> have >>>>>>> to accept the fact that everything isn't mathematical. Consciousness and >>>>>>> the present moment are examples. Clocks don't measure P-time. There is >>>>>>> no >>>>>>> P-time clock that reads P-time. We know we are in the same present >>>>>>> moment >>>>>>> P-time not but having synchronized clocks but by shaking hands and >>>>>>> comparing clocks, and by just living our lives and communicating like we >>>>>>> always did whether our clocks are the same or not. >>>>>>> >>>>>>> There is no clock that displays P-time. However everything is >>>>>>> logical, and I've given the logical reasoning... >>>>>>> >>>>>> >>>>>> What does P-time predict or allow us to explain that special >>>>>> relativity does not or cannot? >>>>>> >>>>>> Thanks for your answers. >>>>>> >>>>>> Jason >>>>>> >>>>>> >>>>>> >>>>>>> On Thursday, January 2, 2014 4:30:37 PM UTC-5, Jason wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Thu, Jan 2, 2014 at 4:17 PM, Edgar L. Owen <edga...@att.net>wrote: >>>>>>>> >>>>>>>>> Liz, >>>>>>>>> >>>>>>>>> We'll let Jason judge whether I answered him or not. >>>>>>>>> >>>>>>>>> >>>>>>>> You did answer, but your answer is that you did not know (you said >>>>>>>> it what was whatever relativity predicts, but relativity also has no >>>>>>>> answer >>>>>>>> without a defined reference frame). >>>>>>>> >>>>>>>> However according to P-time, Sam must be doing *something *at the >>>>>>>> exact moment Pam arrives at her destination. Is that something >>>>>>>> celebrating >>>>>>>> his fifth birthday or not? >>>>>>>> >>>>>>>> If there is some certain thing he is doing at that instant (which I >>>>>>>> think follows from P-time), your P-time theory ought to have some >>>>>>>> mathematical way of providing an answer that question, should it not? >>>>>>>> If it >>>>>>>> does not, then what is the advantage of P-time over special relativity? >>>>>>>> >>>>>>>> Jason >>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Thursday, January 2, 2014 4:14:02 PM UTC-5, Liz R wrote: >>>>>>>>> >>>>>>>>>> On 3 January 2014 10:00, Edgar L. Owen <edga...@att.net> wrote: >>>>>>>>>> >>>>>>>>>>> Liz, >>>>>>>>>>> >>>>>>>>>>> I answered Jason directly. See that post. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> By not answering, yes. >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> There is no preferred CLOCK time frame. There is a shared common >>>>>>>>>>> present moment they both share which is 'preferred' in that sense. >>>>>>>>>>> Again >>>>>>>>>>> you are confusing clock time and Present moment time. See my >>>>>>>>>>> response to >>>>>>>>>>> Jason for one more approach that might make it understandable. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> It is preferred in the sense that it defines an inertial frame. >>>>>>>>>> From what you have said so far that frame is the Earth's rest frame >>>>>>>>>> (or >>>>>>>>>> let's say the rest frame of the CMB, which seems more physically >>>>>>>>>> plausible >>>>>>>>>> - they are fairly close from the point of view of relativistic >>>>>>>>>> travel). >>>>>>>>>> Saying that a frame of reference is special - e.g. that it computes >>>>>>>>>> reality >>>>>>>>>> - should have observable consequences, probably for dispersion in >>>>>>>>>> high >>>>>>>>>> energy cosmic rays. Have you worked out what those are, so they can >>>>>>>>>> be >>>>>>>>>> tested experimentally? So far your theory appears to be just words, >>>>>>>>>> and >>>>>>>>>> from the response you've had so far, not very convincing ones. It >>>>>>>>>> needs a >>>>>>>>>> mathematical underpinning, as I requested way back but haven't yet >>>>>>>>>> seen, >>>>>>>>>> before it can really be called a theory. >>>>>>>>>> >>>>>>>>>> Or if you prefer to stick with just words, please try to show >>>>>>>>>> some reason, any reason, for anyone to think that P-time actually >>>>>>>>>> exists >>>>>>>>>> and does some useful work in explaining reality. Just saying it's >>>>>>>>>> "obvious", and "no one understands you" isn't enough (well, not >>>>>>>>>> unless >>>>>>>>>> you're a teenager, at least.) >>>>>>>>>> >>>>>>>>>> See everyone's responses to your posts, but especially Jason's, >>>>>>>>>> for any number of approaches that might make this understandable. >>>>>>>>>> >>>>>>>>>> -- >>>>>>>>> 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-li...@googlegroups.com. >>>>>>>>> To post to this group, send email to everyth...@googlegroups.com. >>>>>>>>> >>>>>>>>> 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 everything-li...@googlegroups.com. >>>>>>> To post to this group, send email to everyth...@googlegroups.com. >>>>>>> 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 everything-li...@googlegroups.com. >>>>> To post to this group, send email to everyth...@googlegroups.com. >>>>> 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 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. >>> >> >> -- >> 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. >> > > -- > 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. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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<<simultaneity.png>>
