Can the Twin Paradox be simplified?

Discussion in 'Physics & Math' started by timewarp, Nov 20, 2011.

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  1. Trippy ALEA IACTA EST Staff Member

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    The thing is...

    You know that this is a baldfaced lie, because I have in the past admitted errors, that either you have demonstrated, or someone has demonstrated on my behalf in a thread that you have been active in.

    I have no issue admitting that I am wrong. I have invested precisely zero emotional currency in this idea. I even admit my errors in the real world.

    What you have failed to understand, repeatedly, is that if I have not admitted that there is an error, it is because I have not been convinced that there is an error to admit.

    Take the current example, the EEP. My contention is that even the modern phrasing of the EEP is such that as long as all accelerometers measure the same acceleration with the same magnitude and the same direction within the laboratory the acceleration is being measured in (or do so to a good approximation), then the laboratory is being uniformly accelerated, and the EEP can be applied.

    In other words, as long as the accelerometers measure 1G of acceleration in the direction of the floor, then this is equivalent to a lab on earth where all the accelerometers measure 1G of acceleration to the floor.

    You have yet to produce one single thing that demonstrates any of this wrong.

    You have yet to demonstrate that the EEP requires consideration of anything happening outside of the lab, and is dependent on the whole of the spaceship rather than the lab in which the measurements are made.
    You have yet to demonstrate that my understanding of the EEP is wrong.
    You have yet to demonstrate that, to a good approximation, if the lab is small enough, that all accelerometers would show an acceleration of 1G towards the floor.
    You have yet to even recognize the flaw that I actually foresaw in all of this, even though I've given you a hint. RJ Beery has come closer to that than you have.
     
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  3. Trippy ALEA IACTA EST Staff Member

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    And I pointed out that as long as the turn around flip occured such that \(a_{engine}+\omega^2r=9.81\) and as long as the lab was small enough, that all of the accelerometers would read a constant 1G in a direction perpendicular to the floor throughout the entirety of the maneuver.

    You have yet to disprove this.

    I also provided an alternate formulation regarding the launch, and how to handle it.
     
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  5. Tach Banned Banned

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    "My contention" sounds awfully close to the way RJ sounds when he declares mainstream POV as flawed. The point that you continue to miss is the fact you keep talking about applying compensation contraptions to the traveling twin when I have pointed out to you that his being launched off a gravitating body negates the tenet of "the uniformly accelerated probe is located FAR AWAY from any gravitating body". Then you switch to applying goofy acceleration programs to the probe stationary in the UNIFORM gravitational field, thus destroying its "UNIFORM" concept. Then you throw your toys out of the pram when I point out these mistakes. After the toy throwing, you revert to the same high jinks with EEP.


    See above. Why do you keep doing this to yourself? Look, you have wasted an enormous number of posts defending your posts but you are not any closer to writing the formalism that describes it, let alone solving it. On the other hand, I have already solved these exercises, so why are you wasting your energy trying to convince me when you are making zero progress in figuring out the solution to your own exercise? You claim that you are here to learn, at this rate you will never learn.
     
    Last edited: Dec 16, 2011
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  7. Tach Banned Banned

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    This is not a time "dialation" problem, it is a problem of calculating the elapsed time, you are making the same error as RJ and OnlyMe. To make matters worse, the calculation isn't trivial at all, it requires that you understand the notion of geodesic deviation and this requires solving some very complicated equations. You could simplify things a little by using a variational method but you are still faced with some heavy duty math.



    It isn't a "little" planning, it is quite complicated (unless you plan to cut corners in a massive and ugly way). Yes, the above is a simplified case of a more general problem but the math is still very complicated. Even more, constructing the formal description of the exercise is not easy, you need to know GR and EEP is of no use in solving. If you want to learn how to do it, you need to put your energy into it, not into other things.
     
  8. Tach Banned Banned

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    Put the above into a coherent mathematical formalism and I will be able to tell you if it right or not. Dropping isolated formulas like \(a_{engine}+\omega^2r=9.81\) does not constitute a formalism by any stretch of imagination. Take it from launch, how long you accelerate, how long you coast, how do you decelerate and we'll see. Write down the equations for each section, what you have right now is unfalsifiable not because it is correct but because it is just a bunch of random things with no math.
     
  9. Trippy ALEA IACTA EST Staff Member

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    :Roll:
    Because heaven forbid a scientist should use conservative language.

    Look, I class myself as an emperical skeptic, and I work in environmental law enforcement. As far as I'm concerned everything is a contention or an allegation until it is proven or disproven to some standard.

    It is my contention, suggestion, assertion or claim. If you don't like the language tough shit.

    Once again you prove my point - you haven't been following the conversation. It's moved on since those suggestions were made. Do try to keep up.
     
  10. Tach Banned Banned

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    I am not attempting to insult you, I am simply pointing out your many mistakes, if you think that that is an insult, then this is your problem. As an example look at the way you reacted when I pointed the errors in your recent exercise. You did not accept the correction until Trippy told you that you got it wrong. A a matter of fact, I can point to the many times you trolled my posts (and you were shown wrong) and the many personal attacks that you launched against me. If you do not like being proven wrong, check your facts before you post. That simple.
     
  11. Tach Banned Banned

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    True, TS. But there are limits in terms of contentions, rewriting EEP with your additions inserted is way off limits, wouldn't you agree?


    Yes, I followed, you presented a new exercise not realizing that solving it requires even more complicated formalism than before (see my comments on the issues with your new scenario). If you had a prayer at solving the old scenario, now you have none with the new one. I would be thrilled to see you proving me wrong by solving the scenario that you are proposing now.
    In the meanwhile, you never admitted to butchering the EEP, as explained, you simply went on denying that you did anything wrong. You threw a fit over it and then you went on like you made no errors. What is more disturbing, is that you just repeated the same errors.
     
    Last edited: Dec 16, 2011
  12. OnlyMe Valued Senior Member

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    The post has been deleted as I said.

    And that's enough said!
     
  13. Trippy ALEA IACTA EST Staff Member

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    Okay, fine, the wording makes you uncomfortable, while the rest of us are able to infer a common meaning.

    "the twins calculate in advance that the launch will introduce a difference in elapsed proper time of x microseconds"

    It's what I meant in the first place, I admit it was what I should have said in the first place. Mea Culpa.

    I don't recall suggesting it was trivial. It's a little planning in that it amounts to "According to my clock, launch will take this much proper time, according to your clock it will take that much proper time, so I will wait in Orbit at this altitude for this long, at which point both our clocks will show the same amount of elapsed proper time, and then we will begin the experiment in earnest."

    I don't recall suggesting that the EEP was of any use for this step.
     
  14. Tach Banned Banned

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    Ok,

    This is a reasonable post, I think that we can agree on it. Now, how would you go about writing up the mathematical formalism that describes your newly suggested scenario above?
     
  15. Trippy ALEA IACTA EST Staff Member

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    It is precisely the math that is required to describe the accelerationat both turnaround points.

    a[sub]engine[/sub] is the acceleration provided by the engines.
    \(-\omega^2r\) is the acceleration experienced by a rotating object, rotating about a fixed point - IE behaving in the way the lab is in my scenario.

    The point of contention that we were discussing was precisely this, the acceleration experienced in the laboratory during both of the turnaround points (halfway out, and halfway back).
     
  16. OnlyMe Valued Senior Member

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    Tach, have you explained the error or just continued the claim? I could have missed it.

    BTW This is really a good one, I think is goes into the Tach quotes of the day at least.

    Not without a great deal more explaintion and supporting logic than I have noticed.
     
  17. Trippy ALEA IACTA EST Staff Member

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    Do you recall the reason that I have told you, several times across several threads that I am avoiding posting mathmatical formalism at the moment?
     
  18. Tach Banned Banned

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    OK,


    The point of contention was the misuse of EEP but this is beside the point now that you just claimed that you aren't using EEP anymore. Can you put all the above in a coherent formalism so we can talk about it? Like for all the sections of the trip?
     
  19. Tach Banned Banned

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    Yes, many times, last time a few minutes ago. You don't miss it, you just deny it. Not the same thing. But this doesn't seem to matter since you now claim that your new solution doesn't use EEP anymore. So what is your solution to your exercise? Do you use the geodesic deviation? Accelerated motion in GR is very tricky, most applications use motion in the absence of external forces. It is even more tricky than the accelerated motion of a test particle in an em field of arbitrary \(\vec{B},\vec{E}\) and that one is very very tough. The accelerated motion in GR is much , much tougher, so what method are you using?
     
    Last edited: Dec 16, 2011
  20. RJBeery Natural Philosopher Valued Senior Member

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    I'm thinking of an observer that remains in the stationary muon's frame...he would not claim that the muon's life has increased...what he would say is that the accelerated lab has experienced length contractions which make the muon's life APPEAR to be extended to those lab observers, right?
     
  21. OnlyMe Valued Senior Member

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    Tach, you must have edited the wrong post! I did not change anything, I can remember anyway, and have suggested no solution.

    As for the question.., I admit it was phrased poorly, but I really did miss the explanation. I haven't even followed your link yet....

    No, I just checked the link and I don't accept your interpretation as presented. As I have said the condition that the box be FAR AWAY from a gravitating body is essentially a test case for the hypothetical description.

    Just as with the twin paradox question, about applying the solution to a twin that does not return home and being certain that he does still age, which you agreed with..., so it is with the EEP. If it applys FAR AWAY it applies in all cases. It would just not be the only effect acting on or potentially felt by an observer, if it is not FAR AWAY from other sources of gravitation.

    As I said from your earlier quote, if it is a matter of experience, in the early 1900s then it is experienced NOT FAR AWAY from a gravitational field. You feel the same force when you accelerate in a car. It just is not the only force acting on you in that case.

    The equivalence principle just says that the force you feel when accelerating is the same as an equivalent gravitational force in the same direction. Under most cases in experience, it is not a uniform acceleration and so is equivalent to changing gravitational force.

    See, I can tweak it too!
     
  22. Trippy ALEA IACTA EST Staff Member

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    That's not what I said.

    I said I wasn't applying the EEP at lift off.
    I've also said that the experiment in this new format does not begin in earnest until their clocks re-synch as a result of the travelling twin being in orbit. Get it yet?

    I still maintain that if uniform acceleration can be maintained in the laboratory the travelling twin is using to make his measurements from then acceleration can be ruled out as a cause for anything because the twins experience uniform and identical acceleration profiles throughout the duration of the experiment therefore any differences that exist between the must be due to relative velocity, and relative velocity alone.

    If that means that I have to refine and redefine the setup further, then so be it, I'm fine with that.
     
  23. CptBork Valued Senior Member

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    No, the muons can be tracked over time and the lab can unambiguously clock their lifetimes from creation until decay, regardless of how far they actually travel in the lab frame (very routine in particle physics experiments, not just hypothetical). The extended lifetimes as measured in the lab frame are not merely appearance, but well-known, verifiable fact. From the muon's POV, the lab clock runs slower, but it also started ticking before the muon was created or stops after the muon decays, hence an observer in the muon's frame would still agree that the lab still clocks an extended lifetime. So again, how is time dilation distinguished in the case of an initial lab acceleration vs. an initial muon source acceleration?
     
    Last edited: Dec 16, 2011
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