Is Length Contraction in SR physical??
in [Relativity]
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From: glird on 4 Feb 2010 15:10 On Feb 4, 2:03 pm, mpalenik <markpale...(a)gmail.com> wrote: > > Tom Roberts wrote on Wed, 03 Feb 2010 19:52:10 -0600 AND on Feb 4, 2:03 pm, his usual dribble about rotations being the only cause of the length contractions in the equations of STR. Why the pseudonym, Tom?
From: mpalenik on 4 Feb 2010 15:18 On Feb 4, 3:10 pm, glird <gl...(a)aol.com> wrote: > On Feb 4, 2:03 pm, mpalenik <markpale...(a)gmail.com> wrote:> > Tom Roberts wrote on Wed, 03 Feb 2010 19:52:10 -0600 > > AND on Feb 4, 2:03 pm, > his usual dribble about rotations being the only cause of the length > contractions in the equations of STR. > > Why the pseudonym, Tom? Are you trying to say that I'm Tom Roberts? Because I'm not. I can give you my directory entry at Purdue University if you don't believe me.
From: glird on 4 Feb 2010 15:24 On Feb 4, 2:14 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 4, 10:23 am, glird <gl...(a)aol.com> wrote: > > > On Feb 4, 10:57 am, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: > > > > What's wrong with simply stating the truth: "length contraction" is >purely geometrical in the 4-D spacetime of relativity. > > > What's wrong is that length contraction may be something real, but the 4-d spacetime of relativity is a purely geometrical figment of the imagination. > > > glird > > Tom, this is a case in point. PD was referring to a different message he posted on this newsgroup "On Feb 4, 2:14 pm". Which came first, PD, the rooster or its tail?
From: paparios on 4 Feb 2010 15:59 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 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. Miguel Rios
From: Ste on 4 Feb 2010 16:05
On 4 Feb, 13:09, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 3, 10:23 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > Indeed. A belief in the material world is axiomatic, not open to > > > > falsification. > > > > Well, here you see we run into a small problem. > > > > Science is in the business of testing propositions by confronting the > > > consequences of those propositions against *observable* measurement. > > > This is the spine of the scientific method. > > > Indeed. But what if I have axioms that are not testable, but from > > which testable hypotheses can be drawn? If the hypotheses that are > > drawn from the axioms appear to be true, then is it reasonable to say > > that the axioms are true? > > If disproving the testable hypothesis disproves the axiom, then the > axiom is testable. But this relies on falsificationism, which is itself axiomatic. You have yet to explain *why* falsificationism in science is desirable. > > As I say, without instantaneous communication, the hypothesis of > > absolute time is unfalsifiable, but it is an inference that I find > > *necessary* for my coherent understanding. If I did not *presume* that > > events happen independent of their observation, I would not be able to > > apply my intuitions to SR at all. > > First of all, it sounds like you're saying that since you can't > understand relativity, you've made up some of your own ideas that you > like better, which isn't how science works. No, I'm saying that I *do* understand relativity. And can you provide a definition of "science" (the definition remains contentious, you see)? > However, nobody is saying that science says events do not occur > outside of their observation, only that science is only concerned with > describing the observable universe. Science works through observation > and thus can only describe the universe by how it appears to work. This is just rhetoric. No one is talking about describing the universe other than in the way it appears to work - there was never a religion that didn't describe the universe in terms of how it appears to work. > > > > Incidentally, even this axiom of yours that the external world > > > > consists only of what is observed is, itself, an unfalsifiable > > > > position, in that there is no concievable evidence that could disprove > > > > the contention. > > > > Nor did I say that the external world consists ONLY of that which is > > > observable. What I said is that *science* concerns itself with the > > > portion that is observable. The part that is unobservable, such as > > > souls, spirits, deities, simply is not a concern of science. > > > But theoretical scientists are informed by their beliefs about the > > fundamental nature of the real world. It is absurd to say that > > science, by which we mean scientists, are not concerned with the > > unobservable. > > Of course they're not. For example, it's possible that gravity > doesn't exist and there are actually tiny invisible pink elephants > that we can't measure in any way--one for each particle in the > universe--that push every particle to make it look like gravity is > acting on them. You certainly can't disprove this theory. There's no > observable prediction that it makes. Science is only concerned with > the fact that there's an observable thing that appears to be gravity. > Whether it's really elephants or the hand of God, or some sort of > spaghetti monster isn't a scientific question, although there's > certainly no way to rule any of those things out. I'm afraid I simply don't accept this reflects reality. Most scientists do not even remotely entertain the existence of tiny pink elephants, and to reiterate, scientists are informed by their beliefs about the fundamental nature of the real world. |