Is Length Contraction in SR physical??
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From: kenseto on 2 Feb 2010 08:55 On Feb 1, 6:38 pm, artful <artful...(a)hotmail.com> wrote: > On Feb 2, 1:55 am, "kens...(a)erinet.com" <kens...(a)erinet.com> wrote: > > > Is Length Contraction in SR physical?? > > Define 'physical' Look up the dictionary. > > > According the most informed SRian, Tom Roberts, the answer to this > > question is NO. > > I doubt that You are not qualified. > > > His answer is that length contraction is the geometric > > projection effect of the length of a moving meter stick onto the SR > > observer's frame. > > No .. it can be MODELLED by geometry So Modelled by geometry is not physical. > > > When a moving meter stick rejoins the stay at home > > meter stick they will have the same physical length > > Irrelevant So there was no physcial contraction. > > > Furthermore if > > length contraction is physically real how come SR does not predict > > length expansion? > > How come something can't be slower than at rest? No object in the universe is in a state of absolute rest. > > > Is that becasue SR assumes that the observer is in a > > state of absolute rest? > > No. Just rest relative to himself .. everything else is either also > at rest, or has a non-zero speed ROTFLOL....at rest relative to himself is a oxymoron statement. > > > So what does it mean when SR says that a moving meter stick is > > contracted? > > That is it measured as shorter (eg if you measure poles by whether > they fit inside a barn, then the pole is shorter) No measurement of physical length contraction due to relative motion ever been made. > > > The answer: > > You wouldn't know > > > 1. An SR observer assumes that the light path length of his meter > > stick is the same as the physical length of his meter stick. > > Nonsense You are nonsense. > > > 2. Using this standard the light path length of a meter stick moving > > wrt an SR observer is shorter than the light path length of the stay > > at home meter stick. Why? Because light generated at the front end of > > the stick will reach the rear end of the stick sooner for a moving > > meter stick (c+v) according to the stay at home SR observer. > > Totally irrelevant You are totally irrelevant. > > > 3. So according to the SR observer the light path length of a moving > > meter stick is as follows: > > L' = L_o/gamma. > > Nonsense You are nonsense. > > > 4. The above interpretation avoids all the paradoxes that arise due > > to > > the bogus interpretation that a moving meter stick is physically > > contracted. > > There are no paradoxes There are paradoxes if length contraction is physical. You are an idiot. Ken Seto > > > However, the above interpretation is incomplete. Why? > > Because it is nonsense and wrong > > > Because the > > light path length of a meter stick moving wrt the observer may be > > longer than the observer's meter stick. In that case the light path > > length of such meter stick is calculated as follows: > > L' = L_o(gamma) > > This interpretation is included in a new theory of relativity called > > Improved Relativity Theory (IRT). IRT includes SRT as subset. > > Which is nonsense > > > However, > > the equations of IRT are valid in all environments, including > > gravity. > > Nonsense is nonsense no matter where you use it > > > > > A complete description of IRT is available in the following link:http://www.modelmechanics.org/2008irt.dtg.pdf- Hide quoted text - > > - Show quoted text -
From: kenseto on 2 Feb 2010 08:57 On Feb 2, 1:46 am, Sebastian Garth <sebastianga...(a)gmail.com> wrote: > On Feb 1, 8:03 pm, kenseto <kens...(a)erinet.com> wrote: > > > I suggest that you go argue with your SR brother Tom Roberts. He said: > > "Generally, they would consider a "physical length contraction" to > > mean that the object ITSELF gets > > physically shorter. This is manifestly not so in SR". > > Not true. Length contraction is a truly physical phenomena which is > absolutely measurable. Fire two laser beams perpendicularly across the > front and rear of the moving object; the change in length is not an > illusion - within the observer's frame of reference, the object indeed > occupies less space. Hey idiot why don't you do the experiments. Apparently you disagreed with one of the more informed SRians in these NGs.
From: kenseto on 2 Feb 2010 09:01 On Feb 1, 9:17 pm, artful <artful...(a)hotmail.com> wrote: > On Feb 2, 1:03 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > > On Feb 1, 6:22 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > wrote: > > > > "kenseto" <kens...(a)erinet.com> wrote in message > > > >news:b53814cc-0c14-476f-bc2c-a88d5532884e(a)u26g2000yqm.googlegroups.com.... > > > On Feb 1, 2:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 1 Feb, 17:25, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > 2. Secondly, he did NOT say that the length contraction is not > > > > > physical. What he did say is that the word "physical" has an ambiguous > > > > > meaning at best and does not mean what you think it means. What he did > > > > > say is that physics deals with what is MEASURED, and what is measured > > > > > is therefore physical in that sense. It was you and ONLY you that said > > > > > that if it is a geometric effect (which it is), then it CANNOT be > > > > > called a physical effect. Tom did not make that statement. You did. > > > > > I think others will contend that "what is measured" does not > > > > necessarily relate to a physical reality. After all, if I have an > > > > elastic meter ruler, and apply various amounts of tension to it, then > > > > the measurement of an object can be changed without any "physical" > > > > change in that object. On the other hand, if the object to be measured > > > > is also elastic, and I apply the same amount of tension to the object > > > > as well as to the meter ruler, then there are "physical" changes even > > > > though there is no change in the measurement. > > > > > It is this discrepancy that I believe Ken is enquiring about.. > > > > What I am enquiring about are as follows: > > > 1. Tom Roberts said that length contraction is a geometric projection > > > effect....that means that length contraction is not physical > > > contraction. > > > > _______________________ > > > No. You are confusing two different sets of co-ordinates. The length > > > contraction in physical 3D space is real. It can be interpreted as the > > > projection of a 4-vector (space and time) onto 3D space. The 4D vector > > > doesn't change its magnitude, but the 3D projection (which is what we > > > physically measure) certainly does. > > > I suggest that you go argue with your SR brother Tom Roberts. He said: > > "Generally, they would consider a "physical length contraction" to > > mean that the object ITSELF gets > > physically shorter. This is manifestly not so in SR". > > > Ken Seto > > There is no disagreement here .. we non-crackpots are saying the same > things here. You simply don't understand enough of the physics to see > that we are agreeing with each other and disagreeing with you. Hey idiot there is disagreement. You give two meaning for physical that contradict each other. - Hide quoted text - > > - Show quoted text -
From: "Juan R." González-Álvarez on 2 Feb 2010 09:07 Tom Roberts wrote on Mon, 01 Feb 2010 17:42:27 -0600: > Juan R. González-Álvarez wrote: >> eric gisse wrote on Mon, 01 Feb 2010 08:08:39 -0800: >>> kenseto(a)erinet.com wrote: >>>> Is Length Contraction in SR physical?? >>> No, just as it has been explained to you repeatedly since the mid >>> 90's. >> >> From Tom Roberts page: (snip useless LINGUISTIC issues between Tom and kenseto) First, my mistake for attributing the page only to you. The page is from you and Siegmar Schleif. Second, the demonstration of that length contraction occurs is discussed in more detail in: Purcel, Electricity and Magnetism. Third, some people argues that Terrell showed that lenght contraction is not observable (you find this claim in the Wikipedia for instance). Terrel paper says just the contrary: None of the statements here should be constructed as casting any doubt on either the observability ot the reality of the Lorentz contractions, as all the results given are derived from the special theory of relativity. Fourth, as noticed by Chris Hillman, "people sometimes argue over whether the Lorentz-Fitzgerald contraction is 'real' or not" (that is your case vs kenseto). But as Hillmans says, here's a short answer: the contraction can be measured, but the measurement is frame dependent. Whether that makes it "real" or not has more to do with your choice of words than the physics. Indeed Tom, your response was indeed 100% about the choice of words and 0% about the physics. Fiveth, some authors propose a direct experimental measurement of lenght contraction at LHC http://arxiv.org/abs/0710.3489v2 Sixth, in their College Physics, Volumen 10, Serway, Vuille, and Faughn write about, Time-dilation and lenght contraction effects have interesting applications for future space travel to distant stars. -- http://www.canonicalscience.org/ BLOG: http://www.canonicalscience.org/en/publicationzone/canonicalsciencetoday/canonicalsciencetoday.html
From: jem on 2 Feb 2010 09:17
Pete wrote: > Imagine two speres joined by a thread which is extended to its full length > but not under tension > Gently accelerate the two spheres at exactly the same rate. > Does Lorentz contraction increase the tension in the thread (and eventually > cause it to break)? > Of course not, but before rushing to your keyboard to tell me I'm wrong because that's not what it says in Wikipedia (or wherever) - see if you can figure out why I'm not wrong. Hint: what needs to be the case in order for the answer to be "yes"? |