Is Length Contraction in SR physical??
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From: Ste on 4 Feb 2010 21:34 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!".
From: paparios on 4 Feb 2010 21:37 On 4 feb, 19:14, Ste <ste_ro...(a)hotmail.com> wrote: > On 4 Feb, 20:59, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > > > > > > > On 4 feb, 00:53, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 4 Feb, 02:35, YBM <ybm...(a)nooos.fr.invalid> wrote: > > > > > Come on Ste, don't be stupid. Next time you'll choose a frame of > > > > reference which is different only by the origin and will play the > > > > same silly game. > > > > How was it a silly game? I was told simultaneity can never apply to > > > more than one frame, and I've just given you two frames where that is > > > clearly untrue. I suppose if anything, this proves that I *do* > > > understand. > > > After reading your numerous posts, you seem to be certain that a given > > reality is always present, which is independent of what is being > > measured. > > > I propose you the following thought experiment regarding that: > > > a) You are in a space ship A in deep space. Your surroundings are such > > that you experience no gravity at all > > In other words, "let us imagine that we are not in the real world...". > > Well, this is a gedanken which intend to prove that that absolute reality does not exist!!! On the other hand you don't really know what the "real world" is. You just have some senses which tell you about your immediate surrounding conditions and that is it!!! > > > > > and, if you look through a > > window, no stars or galaxies are seen. Basically you are in the middle > > of nowhere. Of course, you don't know if your space ship is moving and > > the ship engines appear to be dead. > > b) Suddenly, you observe another space ship B on your window, which to > > you appears to be approaching your location (it is becoming larger and > > larger in size as time goes by). > > > Now, which of the following conclusions describe the reality of the > > gedanken: > > > 1) Space ship B is sitting still and space ship A is moving at speed v > > towards the location of B. > > 2) Space ship B is approaching at speed v to your space ship A > > location, where A sits still. > > 3) Both space ships are moving in such a way their closing speed is v. > > 4) It is impossible to determine if (1), (2) or (3) reflects reality > > or, in other words, all alternatives (1), (2) and (3) can be true at > > the same time. > > Indeed, on the information available, (4) is the only conclusion that > one can reach. The question is whether this accurately describes > reality (i.e. whether there really is no way to discern absolute > velocity), and whether, indeed, there is no way of discerning absolute > motion. It is a question that I am not yet able to answer. > > Of course, none of this detracts from the reality that, even if it is > indiscernible, I still hold that there is an absolute background > against which either (1), (2), or (3) are true. It is simply that we > don't know which.- In the "real world" there are some that say that the source of the Big Bang could bechosen as an absolute reference, but it is the same case of you aboard the space ship, that is we don't know if the Big Bang was sitting still or moving with respect to something else. At the end it does not matter at all!!! An absolute frame of reference is not needed nor an abosulte time is needed. Miguel Rios
From: Ste on 4 Feb 2010 21:45 On 5 Feb, 01:18, artful <artful...(a)hotmail.com> wrote: > On Feb 5, 12:09 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > But then you're just describing the same thing with different numbers > > - the relationships should all be the same. The contention of > > relativity, surely, is that the "observer" is in a reference frame > > that does *not* encompass the entire universe (because otherwise it > > would be impossible to "change reference frames" without leaving the > > universe itself). > > That is just completely laughable. Why do you bother having > discussions on topics when you have no understanding of the basic > terms. What is the point? > > Don't you know that EVERY reference frame encompasses the entire > universe? > > Don't you know that changing reference frame is just a change of > coordinate values for events? > > Don't you know that whenever you accelerate, you are changing your > frame of reference (ie the frame(s) in which you are measured as being > at rest) .. that there is no need to leave the universe to do that? > > Gees. Let me put my perspective another way then. The "absolute reference frame" involves a reference frame that *does not change under any circumstances* unless one leaves the universe. This is in contrast to the "relative reference frame", that is one that changes with the observer's circumstances.
From: Peter Webb on 4 Feb 2010 21:48 "Ste" <ste_rose0(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.
From: mpalenik on 4 Feb 2010 22:04
On Feb 4, 9:45 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > Let me put my perspective another way then. The "absolute reference > frame" involves a reference frame that *does not change under any > circumstances* unless one leaves the universe. This is in contrast to > the "relative reference frame", that is one that changes with the > observer's circumstances.- Hide quoted text - > > - Show quoted text - A reference frame is nothing more than a point of view, a choice of coordinates. You're saying, in essence, "The 'absolute view point' involves a point of view that *does not change under any circumstances*"--except by definition a view point is simply the way you choose to look at things. Here's another way of thinking of it: you could say there are an infinite number of reference frames to choose from. When you change speed, you're simply picking a different reference frame to use as your "natural" reference frame. However, you could still describe the universe in terms of some other reference frame, you would just have to put your measurements through a coordinate transformation. |