Is Length Contraction in SR physical??
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From: JT on 5 Feb 2010 04:00 On 5 Feb, 07:55, Ste <ste_ro...(a)hotmail.com> wrote: > On 5 Feb, 04:31, mpalenik <markpale...(a)gmail.com> wrote: > > > On Feb 4, 11:22 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > Yes, I'm sure I've employed such a similar wily device when getting a > > > sofa through a doorway before. But we're assuming that the ladder > > > *isn't* rotated. > > > See below. It is rotated not in length and height but in length and > > time. > > It is not "rotated" in any physical sense. > > > > > But there's another way you could rotate it, as well. You can rotate > > > > it into "time". If you run with the ladder, you're "rotating" the > > > > front of it a little bit into the future and the back of it a little > > > > bit into the past. > > > > Haha! I've nearly spat my tea out! I've never heard such a ludicrous > > > statement before I came to sci.physics.relativity! > > > The fact that you find it ridiculous has no bearing on physical > > reality. > > What I do and do not find laughable has *full* bearing on physical > reality. > > > All it demonstrates is that you are not familiar with the > > theory of relativity. > > Then why is it that I seem to be able to understand it so well, even > though I have no idea how to apply it mathematically? > > > > Of course, I understand what you're getting at, although I understand > > > the concept differently. What you're getting at is the effect of > > > propagation delays, > > > No, this has nothing to do with propagation delays. > > What *does* it have to do with then? Bear in mind that a propagation > delay is a *physical* concept. A "rotation in time" is a purely > geometric concept. > > And incidentally, you're not the first person to have said "it has > nothing to do with propagation delay", and yet no one who has said > that has yet described *any* effect (in SR) that is not adequately > explained by propagation delays. > > > > whereby both doors can appear to close > > > simultaneously when, in physical reality, the distant door has already > > > started to open before the near door closed. > > > No, the doors close simultaneously in the frame of the barn but NOT in > > the frame of the moving ladder. This is *after* correcting for any > > "propagation delays" in the observation of the two doors. > > I'm afraid I don't accept this. If it is necessary to make the analogy > more complex, then consider this. The ladder has an observer sitting > on each end of the ladder (in addition to the person stood in the > middle of the barn watching the ladder go by). > > The observer at the fore of the ladder naturally sees the front door > close before the back door, and the front door will start to open > again before the back door has even shut. The observer astern of the > ladder sees the back door close before the front. The observer stood > still in the middle of the barn equidistant from each door sees both > doors close simultaneously. > > Now *of physical necessity*, the observer in the barn who sees the > doors close with the ladder inside, *must* be able to answer our > question. If the ladder is inside the barn, then this observer cannot > *possibly* observe both doors to be shut, unless the ladder is > *wholly* and *physically* inside the barn. > > The question that remains outstanding, is whether the ladder *actually > fits* inside the barn, or whether it crashes before it even gets all > the way into the barn. > > > > But that's why Ken wants a simple answer to the *physical reality*, > > > which is why I devised a setup where the doors are equidistant from an > > > observer (and therefore both must truly close simultaneously), > > > This is what you don't understand, in this scenario, they are ONLY > > closing simultaneously in the barn frame. > > Yes, and the observer is *in* the barn frame. > > > To a moving observer (at > > ANY location, even a moving observer located at the center of the > > barn) they do not close simultaneously. *THIS* is what the theory of > > relativity states. > > Bollocks! The doors cannot possibly close simultaneously "for the > barn", unless they also *appear* to close simultaneously for the > stationary observer positioned inside the barn and equidistant from > each door. Ste it is not possible to make them understand your scenario, in their world there could not possibly be any such thing like an observer upon the rod. And the reason for this is that the theory was not made to take it into account. They have no idea about what simultaneously is they, and they are totally ignorant and clueless regarding any fact dealing with simultanity and causuality. They prefer Einsteins dodo. They use screwed Lorentz projections and think they are projections of the physical reality, this is how deranged they are. The pole can of course never fit in the barn if the doors close simultaneous ***in the barn frame*** frame, Their argument is basicly that if the doors do what you say close simultaneously in the barn frame. Then the travelling observer on the rod will not see them close simultaneously, so simultanity is framedependent in SR. Now you may say that is ridiculous to call this simultanity, what really happen is of course the light travelling from door A at c+v and B at c-v relative the observer. So in SR one door must close later to be perceived to be simultaneous from the rod frame, that is how they fit a to long pole in the barn, they just have to low IQ to understand it, Since they have postulated that light travel at c relative any observer they will never be able to understand what really happens. You see they really think that their Lorentz screwed simultanity is *real* since their observer is at center of the rod the doors really is closing simultaneous as a universal truth, and of course it is not. They do not simply understand that their faulthy view of simultanity let the barn be longer than it really is, one door is simply closing later in the barn frame. But the monkeys is to stupid to understand this, so i should just leave it there. The idiots will be subjects for some good laught when future generations read their bullocks. > Also, even though this has nothing to do with the analogy as I > presented it, an observer moving along an axis that is always > equidistant from both doors *can* be moving and also observe the doors > to be closing simultaneously. > > > > > > > > > What a moving observer percieves as "time" is the direction of his > > > > motion through 4 dimensional spacetime. What he percieves as "space" > > > > is the 3 dimensional volume perpendicular to that direction. Thus, > > > > "space" in the moving frame is not the same as "space" in the rest > > > > frame. It extends part way into the future along one direction and > > > > part way into the past along the other (in the rest frame). > > > > Indeed. What's most worrying for me is that I can understand exactly > > > what you're describing, and yet you can't understand what me and Ken > > > are asking. > > > > Incidentally, if you understand the maths of SR (I don't), perhaps you > > > should try testing this one out. Have the observer in the middle of > > > the barn, the doors close simultaneously according to that observer, > > > and the ladder travelling at something just less than the speed of > > > light. Can the observer possibly observe the ladder inside the barn > > > with both doors closed in this situation?- Hide quoted text - > > > This is what the original scenario represents. An observer, at rest > > with respect to the barn, in the center of the barn, sees both doors > > close at the same time with the ladder inside the barn. The person > > running with the ladder does not see them close simultaneously, but > > sees the front and back doors close and open at just the right time > > for him to run through. This is what the math says and is a very > > basic problem that might be given to a student who has just started > > studying relativity. > > Listen, the question isn't what a moving observer would observe. The > question is what the observer stationary inside the barn would > observe. > > He cannot possibly observe the ladder move into the barn, and then for > the doors to close simultaneously, and the ladder physically fit > inside. If the maths seems to be suggesting this, then you're > misinterpreting the maths. > > Incidentally, see this paper:http://arxiv.org/PS_cache/arxiv/pdf/0710/0710.3489v2.pdf > > As you can see, the effect that you allege, of physical length > contraction, has never been experimentally observed.- Dölj citerad text - > > - Visa citerad text -
From: JT on 5 Feb 2010 04:07 On 5 Feb, 08:08, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 5, 1:55 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 5 Feb, 04:31, mpalenik <markpale...(a)gmail.com> wrote: > > > > On Feb 4, 11:22 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > Yes, I'm sure I've employed such a similar wily device when getting a > > > > sofa through a doorway before. But we're assuming that the ladder > > > > *isn't* rotated. > > > > See below. It is rotated not in length and height but in length and > > > time. > > > It is not "rotated" in any physical sense. > > > > > > But there's another way you could rotate it, as well. You can rotate > > > > > it into "time". If you run with the ladder, you're "rotating" the > > > > > front of it a little bit into the future and the back of it a little > > > > > bit into the past. > > > > > Haha! I've nearly spat my tea out! I've never heard such a ludicrous > > > > statement before I came to sci.physics.relativity! > > > > The fact that you find it ridiculous has no bearing on physical > > > reality. > > > What I do and do not find laughable has *full* bearing on physical > > reality. > > > > All it demonstrates is that you are not familiar with the > > > theory of relativity. > > > Then why is it that I seem to be able to understand it so well, even > > though I have no idea how to apply it mathematically? > > You have repeatedly expressed an incorrect understanding of the theory > and refuse to acknowledge it, despite the fact that multiple people, > including myself, have explained that your interpretation is flawed. > Why you think you understand it "so well" is beyond me. > > > > > Of course, I understand what you're getting at, although I understand > > > > the concept differently. What you're getting at is the effect of > > > > propagation delays, > > > > No, this has nothing to do with propagation delays. > > > What *does* it have to do with then? Bear in mind that a propagation > > delay is a *physical* concept. A "rotation in time" is a purely > > geometric concept. > > > And incidentally, you're not the first person to have said "it has > > nothing to do with propagation delay", and yet no one who has said > > that has yet described *any* effect (in SR) that is not adequately > > explained by propagation delays. > > If you work through the math, you'll see that the effects I'm > describing are *after* propagation delay has been accounted for. It > is *not* adequately accounted for by propagation delays. Those must > be accounted for *separately*. > > > > > > > > > > > whereby both doors can appear to close > > > > simultaneously when, in physical reality, the distant door has already > > > > started to open before the near door closed. > > > > No, the doors close simultaneously in the frame of the barn but NOT in > > > the frame of the moving ladder. This is *after* correcting for any > > > "propagation delays" in the observation of the two doors. > > > I'm afraid I don't accept this. If it is necessary to make the analogy > > more complex, then consider this. The ladder has an observer sitting > > on each end of the ladder (in addition to the person stood in the > > middle of the barn watching the ladder go by). > > > The observer at the fore of the ladder naturally sees the front door > > close before the back door, and the front door will start to open > > again before the back door has even shut. The observer astern of the > > ladder sees the back door close before the front. The observer stood > > still in the middle of the barn equidistant from each door sees both > > doors close simultaneously. > > No, this is not how special relativity works. You must *first* > account for the propagation delays. The observers at the front and > rear of the latter, after accounting for propagation delays, will each > see the door open and shut at the same time. > > The relativistic effects have to do with differences measured due to > VELOCITY, NOT POSITION. > > > > > Now *of physical necessity*, the observer in the barn who sees the > > doors close with the ladder inside, *must* be able to answer our > > question. If the ladder is inside the barn, then this observer cannot > > *possibly* observe both doors to be shut, unless the ladder is > > *wholly* and *physically* inside the barn. > > > The question that remains outstanding, is whether the ladder *actually > > fits* inside the barn, or whether it crashes before it even gets all > > the way into the barn. > > It fits in the barn in the barn frame, where both ends are in the barn > simultaneously. > > > > > > > > > > > But that's why Ken wants a simple answer to the *physical reality*, > > > > which is why I devised a setup where the doors are equidistant from an > > > > observer (and therefore both must truly close simultaneously), > > > > This is what you don't understand, in this scenario, they are ONLY > > > closing simultaneously in the barn frame. > > > Yes, and the observer is *in* the barn frame. > > > > To a moving observer (at > > > ANY location, even a moving observer located at the center of the > > > barn) they do not close simultaneously. *THIS* is what the theory of > > > relativity states. > > > Bollocks! The doors cannot possibly close simultaneously "for the > > barn", unless they also *appear* to close simultaneously for the > > stationary observer positioned inside the barn and equidistant from > > each door. > > They DO appear to close simultaneously for the stationary observer at > the center of the barn. I have never said otherwise. > > > > > Also, even though this has nothing to do with the analogy as I > > presented it, an observer moving along an axis that is always > > equidistant from both doors *can* be moving and also observe the doors > > to be closing simultaneously. > > Only if you fail to take into account relativity. Under Newtonian > physics, you are correct. Under relativistic physics, you are not. > > > > > > > > > > > > What a moving observer percieves as "time" is the direction of his > > > > > motion through 4 dimensional spacetime. What he percieves as "space" > > > > > is the 3 dimensional volume perpendicular to that direction. Thus, > > > > > "space" in the moving frame is not the same as "space" in the rest > > > > > frame. It extends part way into the future along one direction and > > > > > part way into the past along the other (in the rest frame). > > > > > Indeed. What's most worrying for me is that I can understand exactly > > > > what you're describing, and yet you can't understand what me and Ken > > > > are asking. > > > > > Incidentally, if you understand the maths of SR (I don't), perhaps you > > > > should try testing this one out. Have the observer in the middle of > > > > the barn, the doors close simultaneously according to that observer, > > > > and the ladder travelling at something just less than the speed of > > > > light. Can the observer possibly observe the ladder inside the barn > > > > with both doors closed in this situation?- Hide quoted text - > > > > This is what the original scenario represents. An observer, at rest > > > with respect to the barn, in the center of the barn, sees both doors > > > close at the same time with the ladder inside the barn. The person > > > running with the ladder does not see them close simultaneously, but > > > sees the front and back doors close and open at just the right time > > > for him to run through. This is what the math says and is a very > > > basic problem that might be given to a student who has just started > > > studying relativity. > > > Listen, the question isn't what a moving observer would observe. The > > question is what the observer stationary inside the barn would > > observe. > > A stationary observer at the center of the barn observes both doors > closing simultaneously while the ladder is inside. I have said this > before. Despite the fact that your flawed understanding of relativity > prohibits this, this is what happens. > > > > > He cannot possibly observe the ladder move into the barn, and then for > > the doors to close simultaneously, and the ladder physically fit > > inside. If the maths seems to be suggesting this, then you're > > misinterpreting the maths. > > No, you don't understand the math, let alone relativity itself.- Dölj citerad text - > > - Visa citerad text -- Dölj citerad text - > > - Visa citerad text -- Dölj citerad text - > > - Visa citerad text -- Dölj citerad text - > > - Visa citerad text - Oh and i want to add one thing!!!! Tom Roberts is not the brightest star on the sky, but he understand what is happening is a geometrical projection of the barn in the pole frame. Way to go Roberts, next time maybe we could deal with projection of time due to Lorentz transform. JT
From: Ste on 5 Feb 2010 05:06 On 5 Feb, 08:42, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 5, 3:24 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > If you work through the math, you'll see that the effects I'm > > > describing are *after* propagation delay has been accounted for. It > > > is *not* adequately accounted for by propagation delays. Those must > > > be accounted for *separately*. > > > Then give me a concrete example of the difference between what would > > be predicted with 'mere' propagation delay, and the actual predictions > > of SR, and then we can discuss it. > > In this particular thought experiment with the barn and the ladder, > I've tried to explain the different to you but you refuse to believe. > In the full relativistic framework, an observer at rest in the center > of the barn can see both doors shut at the same time while the ladder > is entirely inside of the barn. This cannot be accounted for with > mere propagation delay. That is for sure. But I'm not aware of any evidence in support of this hypothesis. > There are other effects of relativity that cannot be accounted for > with propagation delay, such as increased half lives of particles > moving at high speeds (which have been measured), but they're not > related to this thought experiment. Ah, but I have a theory that might explain that. > > > No, this is not how special relativity works. You must *first* > > > account for the propagation delays. The observers at the front and > > > rear of the latter, after accounting for propagation delays, will each > > > see the door open and shut at the same time. > > > > The relativistic effects have to do with differences measured due to > > > VELOCITY, NOT POSITION. > > > I accept that there are effects due to velocity. But in this context, > > what of them? > > The fact that the discrepancy in simultaneity between the closing and > opening of the two doors only occurs for observers at different > velocities. Not necessarily. I refer back to my earlier example where an observer follows a course that always remains equidistant from both events (and it doesn't matter what speed, or what direction, as long as you always maintain equidistance from both events). > It does NOT occur for observers at the same velocity in > different locations. Once you account for propagation delay, there is > no descrepancy in simultanaity for observers at the same speed. But > the discrepancy REMAINS for observers at different speeds. Not necessarily. See previous. > > And if you say it does, then I'm going to ask you, are you *sure* it > > does? Have you done the calculations? > > Yes. Proper length (squared) is dx^2 + dy^2 + dz^2 - cdt^2. The fact > that the proper length is greater than that of the barn is accounted > for by the fact that some of the ladder is rotated in time, which is > what I've been trying to explain to you. Then what part of SR requires that the effect be real instead of merely observed? Isn't it more plausible to say that the *observed* position of the ladder, doors, etc, are "rotated in time", but that what is observed does not reflect physical reality? > > > > Also, even though this has nothing to do with the analogy as I > > > > presented it, an observer moving along an axis that is always > > > > equidistant from both doors *can* be moving and also observe the doors > > > > to be closing simultaneously. > > > > Only if you fail to take into account relativity. Under Newtonian > > > physics, you are correct. Under relativistic physics, you are not. > > > I don't believe you. Are you sure you have done the calculations and > > verified this for yourself? > > Did you read my second post where I corrected this? I misread your > original statement as "a moving observer equidistant between the two > doors," in which case, it is in general false. But yes, if the axis > of motion is perpendicular to the line between the two doors, then you > are correct. Yes I did see that. And of course I am correct. ;) > > How can the doors possibly not shut simultaneously with each other if > > you are, by definition, always maintaining equidistance from both, and > > you are moving with the same velocity relative to both? > > This is the difference between Newtonian mechanics and relativity. In > relativity, when you move, as I've tried to explain before, some of > your "space" axis gets rotated into your "time" axis, and so events in > front of you are slighty in the FUTURE of the stationary frame, which > events behind you are slightly in the PAST of the stationary frame. It's not clear what you mean when you say "in front" and "behind".
From: Ste on 5 Feb 2010 05:16 On 5 Feb, 08:52, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 5, 3:49 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > Ah, so does this leave a loophole where I might be right if I can > > plausibly attack the evidence relating to the invariance of the speed > > of light?- Hide quoted text - > > If you can attack the invariance of something moving at the speed c > (it doesn't have to be light specifically. For example, if it were > found that light moved at less than c, it wouldn't matter), then the > entire theory as I've described it would fall apart. My hypothesis is not that 'c' is variant, but that it is only invariant relative to a medium, or an absolute background - which I'm sure you'll groan is basically a return to the luminiferous aether. But I am quite serious, and I think you'll be surprised. I'm dealing with this in the other thread entitled "Photon and the speed of light".
From: Ste on 5 Feb 2010 05:25
On 5 Feb, 09:00, JT <jonas.thornv...(a)hotmail.com> wrote: > > Ste it is not possible to make them understand your scenario, in > their world there could not possibly be any such thing like an > observer upon the rod. > And the reason for this is that the theory was not made to take it > into account. > > They have no idea about what simultaneously is they, and they are > totally ignorant and clueless regarding any fact dealing with > simultanity and causuality. They prefer Einsteins dodo. In truth if you actually read a lot of what Einstein said, he was more often arguing against the sort of nonsense that prevails today, and he was actually marginalised in the scientific community as time went on. > They use screwed Lorentz projections and think they are projections of > the physical reality, this is how deranged they are. The pole can of > course never fit in the barn if the doors close simultaneous ***in the > barn frame*** frame, > > Their argument is basicly that if the doors do what you say close > simultaneously in the barn frame. Then the travelling observer on the > rod will not see them close simultaneously, so simultanity is > framedependent in SR. > > Now you may say that is ridiculous to call this simultanity, what > really happen is of course the light travelling from door A at c+v and > B at c-v relative the observer. > > So in SR one door must close later to be perceived to be simultaneous > from the rod frame, that is how they fit a to long pole in the barn, > they just have to low IQ to understand it, Indeed, this is precisely my understanding. > But the monkeys is to stupid to understand this, so i should just > leave it there. The idiots will be subjects for some good laught when > future generations read their bullocks. Though some say youth doth rule me. |