Is Length Contraction in SR physical??
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From: Peter Webb on 9 Feb 2010 10:18 If it can be shown that the arguments I'm making about an absolute aether require a length contraction, then I'd probably accept it, particularly if a credible physical explanation can be given. Otherwise, I reserve judgment - that is, I neither deny it nor accept it. _______________________________________ That's fine, unless you design satellite GPS system, are a professional astronomer or science teacher, or help design particle accelerators or nuclear power plants.
From: jem on 9 Feb 2010 10:38 kenseto wrote: > On Feb 9, 12:02 am, artful <artful...(a)hotmail.com> wrote: >> On Feb 9, 2:53 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >>> The question is whether the scientists who claim to understand SR >>> actually do understand it in a physical way, or whether they have just >>> learned the maths by rote and swallowed the fallacious explanations >>> they've been given for what they observe. >> Please put forward what explanations of SR you are referring to, and >> your evidence / logical argument that proves they are fallacious. >> Please also provide non-fallacious explanations as alternatives. > > For example in the barn and the pole paradox: Sr says that a 80 ft > pole can fit into a 40 ft barn completely with the ends of the pole > not sticking out of the barn. At the same time SR claims that the same > pole cannot fit into the barn completely and the ends of the pole is > sticking out of the barn. Yes, that's what SR says, Seto, and it's what thousands upon thousands of people over the past 100 years have come to recognize (in relatively short-order) isn't contradictory when time is relative. But not you, Seto - even after spending more than 15 years "thinking" about it, and after being on the receiving end of hundreds of patient explanations, you still can't conceive how such a thing could be possible. Of course you think it's impossible for two kids and their dog to stand in line, so your inability to understand even the simplest concepts of SR is certainly not surprising.
From: PD on 9 Feb 2010 11:30 On Feb 8, 3:09 pm, kenseto <kens...(a)erinet.com> wrote: > On Feb 8, 3:09 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 8, 12:38 pm, kenseto <kens...(a)erinet.com> wrote: > > > > On Feb 8, 11:42 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 7, 7:34 am, kenseto <kens...(a)erinet.com> wrote: > > > > > > On Feb 6, 10:57 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > On Feb 6, 9:02 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > On 6 Feb, 17:16, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > On Feb 5, 8:14 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > > > On 5 Feb, 16:00, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > > > On Feb 4, 9:57 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > > > > > On 5 Feb, 02:48, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > > > > > > > > > > wrote: > > > > > > > > > > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > > > > > > > > > > >news:3979bca1-a35e-4399-bc71-75d2fc680757(a)21g2000yqj.googlegroups.com... > > > > > > > > > > > > On 5 Feb, 01:12, artful <artful...(a)hotmail.com> wrote: > > > > > > > > > > > > > > On Feb 5, 11:49 am, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > > > > > > > > On Feb 4, 6:04 pm, mpalenik <markpale...(a)gmail.com> wrote: > > > > > > > > > > > > > > > > On Feb 4, 5:59 pm, "kens...(a)erinet.com" <kens...(a)erinet.com> wrote: > > > > > > > > > > > > > > > > > It it does violate the PoR. You made the contradcictory claims that > > > > > > > > > > > > > > > > the pole can fit into the barn physically (materially) an at the > > > > > > > > > > > > > > > > same > > > > > > > > > > > > > > > > time you claim that the pole cannot fit into the barn physically > > > > > > > > > > > > > > > > (materially)......that a violation of the PoR. > > > > > > > > > > > > > > > > No. The doors are not closed simultaneously in the pole's frame, nor > > > > > > > > > > > > > > > are the two ends of the pole simultaneously in the barn in the pole's > > > > > > > > > > > > > > > reference frame. In the barn's frame, the two ends of the pole are in > > > > > > > > > > > > > > > the barn simultaneously and the doors shut simultaneously. In the > > > > > > > > > > > > > > > pole's frame, the two ends of the pole are in the barn at different > > > > > > > > > > > > > > > times and the doors shut at different times. > > > > > > > > > > > > > > > Sigh..You are making the contradictory claims: > > > > > > > > > > > > > > 1. The pole can fit into the barn with both doors close > > > > > > > > > > > > > > simultaneously. > > > > > > > > > > > > > > In the frame of the barn > > > > > > > > > > > > > > > 2. The pole cannot fit into the barn with both doors close > > > > > > > > > > > > > > simultaneously. > > > > > > > > > > > > > > In the frame of the pole > > > > > > > > > > > > > > Two different meanings for 'simultaneously'. So they are not > > > > > > > > > > > > > contradictory > > > > > > > > > > > > > > You really are not very good at thinking or arguing logically. > > > > > > > > > > > > > He seems perfectly reasonable to me. > > > > > > > > > > > > > He's saying that, if one stands in the middle of the barn equidistant > > > > > > > > > > > > from the doors on each side, and one closes the doors simultaneously > > > > > > > > > > > > (i.e. what I would call "absolutely simultaneously", but which for > > > > > > > > > > > > conveience we'll say "simultaneous according to an observer standing > > > > > > > > > > > > equidistant from each door), then is it possible that both doors can > > > > > > > > > > > > appear closed while the ladder is observed to be inside the barn. > > > > > > > > > > > > > It's a simple question, and the answer is "no!". > > > > > > > > > > > > > ______________________________ > > > > > > > > > > > > Its a simple question, and the answer is "yes". It is quite easy to devise > > > > > > > > > > > > an inertial frame in which the doors both appear closed and the ladder is > > > > > > > > > > > > fully contained in the barn. > > > > > > > > > > > > The question wasn't whether "an inertial frame can be devised...". > > > > > > > > > > > Even I can think of situations where it would *appear* that the ladder > > > > > > > > > > > was inside and both doors closed. The question is whether this is an > > > > > > > > > > > artefact of observation, or whether the ladder is actually inside with > > > > > > > > > > > both doors closed. The answer remains "no, the ladder does not fit > > > > > > > > > > > inside with both doors closed". > > > > > > > > > > > There is a simple test. > > > > > > > > > > We can determine whether the doors closed simultaneously. We do this > > > > > > > > > > using the test of simultaneity I indicated to you above: > > > > > > > > > > 1. Have the door-closings generate signals that travel at identical > > > > > > > > > > speeds from either event. > > > > > > > > > > 2. Have a detector positioned at equal distance from the barn doors. > > > > > > > > > > 3. If the detector receives the signals from the barn door-closings at > > > > > > > > > > the same time, then the two doors closed simultaneously unambiguously. > > > > > > > > > > You and I have agreed on this procedure. > > > > > > > > > > If the detector is stationary, then yes we agree that this determines > > > > > > > > > simultaneity. > > > > > > > > > > > Secondly, we can determine whether any part of the pole was outside > > > > > > > > > > the barn when those doors were closed by looking for the marks the > > > > > > > > > > ends of the pole would have made on the door. In the absence of those > > > > > > > > > > marks, we can safely conclude that the entire pole was inside the barn > > > > > > > > > > at the time the doors were closed. > > > > > > > > > > Agreed. I would expect this test is definitive, were it possible to > > > > > > > > > carry out. > > > > > > > > > And this has been tested in equivalent experiment. Documented. > > > > > > > > Has it really? Which experiment was that, because my sources say that > > > > > > > length contraction has *never* been experimentally observed. > > > > > > > I already told you the answer to that. Please look again. > > > > > > > > > Seto does not read experimental papers, because he finds them > > > > > > > > confusing. So instead he believes what makes sense to him, rather than > > > > > > > > letting experimental results tell him something different. > > > > > > > > You have to concede at least the possibility Paul that the reason Ken > > > > > > > finds them confusing, and so do I, is because *we* can see that they > > > > > > > rest on certain assumptions. That is, assumptions that you've > > > > > > > internalised, and assumptions which me and Ken reject. > > > > > > > In Seto's case, it has more to do with thinking that SR says something > > > > > > it does not. I haven't yet figured out whether you are in the same > > > > > > boat. > > > > > > The only assumptions I make are those that have testable consequences. > > > > > > Which ones of those do you think I have that you reject? > > > > > > So are you saying that SR doesn't say that the pole can be completely > > > > > inside the barn with both doors close simultaneously? > > > > > SR *certainly* does not say that this statement holds true in both > > > > barn frame and pole frame. > > > > If you thought it did, then you never understood what SR says. > > > > I didn't say that that statement hold true in both barn and pole > > > frame. > > > Yes, you did. Two days ago you said just this: "The pole observer have > > to agree with the barn observer that the pole > > is completely inside the barn with both door close simultnaeously." You said: "The pole observer have to agree with the barn observer that the pole is completely inside the barn with both door close simultnaeously." You THEN said "So are you saying that SR doesn't say that the pole can be completely inside the barn with both doors close simultaneously? I ask this question because that's what I think SR says. I told you No, SR does NOT say this, and neither does the PoR. You THEN said, "I didn't say that that statement hold true in both barn and pole frame." SR consistently says the two observers do not have to agree on what happens. You first say the two observers have to agree, and then you say they don't. Admit it, Ken, you've made contradictory statements when SR made none. > > So??? What I said here is that I disagree with the SR assertions that > the pole is physically contracted in one frame and not physically > contracted in another frame. Since there is only one pole it is either > contracted or not contracted....but not both. A physically contracted > pole cannot suddenly not physically contracted. That's why informed > physicists such as Tom Roberts reject the idea of physical length > contraction.... instead he said that the length contraction idea in SR > is a geometric projection of the pole unto the barn frame. > > Ken Seto > > > > > You said they have to agree. They do not. That does not make a > > contradiction. > > > > I said that SR claim that the pole is physically contracted so > > > that it can fit into the barn and that SR also made the contradictory > > > assertion that the same pole is not physically contracted so that it > > > is not able to fit into the barn. > > > > > > I ask this > > > > > question because that's what I think SR says. > > > > > You are wrong about that.- Hide quoted text - > > > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -
From: PD on 9 Feb 2010 11:32 On Feb 8, 2:58 pm, kenseto <kens...(a)erinet.com> wrote: > On Feb 8, 3:25 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > On Feb 7, 8:39 am, kenseto <kens...(a)erinet.com> wrote: > > > > > When Ken started asking these questions 15 years ago, they were > > > > reasonable questions. When after a couple of years it was clear he was > > > > not listening to the answers given to his questions, the tone of the > > > > responses became a little different. > > > > Why should I listen to what you said when you did made sense.?? > > > Ken, it isn't wise to stop listening to people if you do not > > understand what they are saying. It would be important in that case to > > say, "I don't understand what you are saying. Can you explain it > > differently so I can understand it?" > > I don't listen to you because you keep on making contradictory claims. > For example the pole is physically contracted to fit the barn and at > the same time the pole does not fit into the barn because it is not > physically contracted. Those are not contradictory claims. Those are different accounts made in different reference frames. There is no requirement that the accounts be identical in different reference frames, and therefore they are not contradictory. Nor is it contradictory to say that a falling ball has a straight-line trajectory AND a parabolic trajectory in the same fall. Galileo knew that. I don't see why you don't understand that.
From: Ste on 9 Feb 2010 11:35
On 9 Feb, 15:18, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > If it can be shown that the arguments I'm making about an absolute > aether require a length contraction, then I'd probably accept it, > particularly if a credible physical explanation can be given. > Otherwise, I reserve judgment - that is, I neither deny it nor accept > it. > > _______________________________________ > That's fine, unless you design satellite GPS system, are a professional > astronomer or science teacher, or help design particle accelerators or > nuclear power plants. I've already provided one round of sources Peter, but consider also reading this paper, which again emphasises the purely theoretical basis of length contraction, which has *never* been observed, and does not look set to be observed in the near future: http://arxiv.org/abs/0808.1117v1 |