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Natural Science Forum / Physics / Relativity / November 2006When can we use special relativity?
When can we use special relativity? I'd like to have some comments on this. But I think the simple answer is that we can use special relativity as long as no force fields are involved. Any comments? Fitz > When can we use special relativity? > [quoted text clipped - 6 lines] > > Fitz You use SR when there is significant motion in free-space to cause Maxwell's time independent equations to exhibit errors due to the finite speed of light. (PoR) Time-independent Maxwell equations Time-dependent Maxwell's equations http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html http://en.wikipedia.org/wiki/Free_space Sue... Sue, I never expected to come across you here. By the way your book has been sent. Good luck. Fitz > > When can we use special relativity? > > [quoted text clipped - 17 lines] > > Sue... > Sue, > > I never expected to come across you here. Your name is Dennis - and you are talking to yourself. Dirk Vdm > By the way your book has been > sent. Good luck. [quoted text clipped - 22 lines] >> >> Sue... Welcome to usenet! [bottom posting moved accoring to usenet policy] :o) > > > When can we use special relativity? > > > [quoted text clipped - 17 lines] > > > > Sue... > Sue, > > I never expected to come across you here. By the way your book has been > sent. Good luck. > > Fitz Many thanks. Don't let the H.G Wells fans try to convince you that Einstein made beads vanish from an abacus or any other supernatural stuff. ;-) Forewarned is four arms... er something like that. http://wwwcdf.pd.infn.it/~loreti/science.html http://www.quackwatch.org/01QuackeryRelatedTopics/pseudo.html Sue... > Sue, > > I never expected to come across you here. By the way your book has been > sent. Good luck. > > Fitz BTW, Dirk Van de moortel is some kind of psychotic that thinks there are two posters on the n.g. himself and an imposter. He even wagers with people they don't know their own Identity. I think the bellhop paradox must have fried his brain. I lucked out. He thinks I am Dennis McCarthy from USNO. http://www.google.com/search?hl=en&safe=off&sa=X&oi=spell&resnum=0&ct=result&cd= 1&q=dennis+mccarthy+usno&spell=1 I don't mind being confused with Dennis but I doubt he wants to be confused with me so you have my standard disclaimer on Dennis' behalf. Sue... > > > When can we use special relativity? > > > [quoted text clipped - 17 lines] > > > > Sue... > When can we use special relativity? When no, or at the most only weak, gravitational fields are present. > I'd like to have some comments on this. > > But I think the simple answer is that we can use special relativity as > long as no force fields are involved. No - eg it can be used when EM fields are present. Thanks Bill > Any comments? > > Fitz > > When can we use special relativity? > > When no, or at the most only weak, gravitational fields are present. Does gravity change retarded potential or the speed of light? Sue... > > I'd like to have some comments on this. > > [quoted text clipped - 9 lines] > > > > Fitz > > "fitz" <zeusrdx@yahoo.com> wrote in message > > > When can we use special relativity? > > > > When no, or at the most only weak, gravitational fields are present. > > Does gravity change retarded potential or the speed of light? We can use SR locally in any old case, provided "local" is defined as "not on such scales of time, distance and precision where SR begins to fail"; in other words, we can use it, except when we can't. ;-) Hmm... though what does that say about laboratories not in free fall? I dropped my pencil... oops! Gravitational effect! Can't use SR! Perhaps we can continue to use SR in some situations with significant gravitational effects (like falling pencils), under an approximation of Newtonian gravity; i.e., where a gravitational force is added by hand. And what do _you_ think about the connection between Unruh and Hawking radiation, Sue? The question is vexing me: together can they smugly say, yes, we've resolved the question of whether uniformly accelerated charges radiate, and the seeming contradiction with the equivalence principle...? >> > "fitz" <zeusrdx@yahoo.com> wrote in message > [quoted text clipped - 19 lines] > charges radiate, and the seeming contradiction with the equivalence > principle...? You may find the following of interest. BTW I am with Feynman. http://www.mathpages.com/home/kmath528/kmath528.htm Thanks Bill > You may find the following of interest. BTW I am with Feynman. > http://www.mathpages.com/home/kmath528/kmath528.htm Thanks for the reference. These pages seem to be anonymous, but they are certainly of high quality. > > > "fitz" <zeusrdx@yahoo.com> wrote in message > [quoted text clipped - 7 lines] > "not on such scales of time, distance and precision where SR begins to > fail"; in other words, we can use it, except when we can't. ;-) That's the sort of non answer I'd expect from Hobba or Roberts...but then I posed the question to Hobba so I'll give you a B+ on pinch hitting. ;-) > Hmm... though what does that say about laboratories not in free fall? > I dropped my pencil... oops! Gravitational effect! Can't use SR! > Perhaps we can continue to use SR in some situations with significant > gravitational effects (like falling pencils), under an approximation of > Newtonian gravity; i.e., where a gravitational force is added by hand. The question is not when can you *abuse* SR. It is important that we don't attach inertial effects where the term "uniform motion" is used in the 1920 paper. The 1923 Gothenburg lecture offer some insight why. The Tajmar / de Matos experiment is another clue. > And what do _you_ think about the connection between Unruh and Hawking > radiation, Sue? The question is vexing me: together can they smugly > say, yes, we've resolved the question of whether uniformly accelerated > charges radiate, and the seeming contradiction with the equivalence > principle...? You are questioning the validity of GR's pseudo-space? In SR, does Einstein get away with dumping the nearfield effects of coupling structures into farfield regions of free space ? As a formalism for a few specific calculations it suceeds but on the whole it distorts more than it clarifies and leads to well known paradox when misapplied. EM is a radiative mechanism so 377 ohms seems complete and is much less ambiguous. http://en.wikipedia.org/wiki/Wave_impedance http://en.wikipedia.org/wiki/Free_space In GR, does Einstein get away with dumping the nearfield effects of coupling structures (Mach) into farfied regions of free space ? While the the excuses for employing such sleight of hand may seem better than the SR case, the distortion and confusion are even more severe. Gravity is as much inductive as radiative and nearfield reigons aren't so easy to define. We don't even know a frequency or mode so it is a bold assumption that we can homogenize some particular region of space and employ a gravitational equivalent to the 377 ohms that EM sees. Mercury's orbit and galactic orbits would suggest it is a bad assumption. For most physicists, the business of spatially moving mass and energy comes at a high price. A jar of jam at your favorite grocer is not the same as a jar of jam in your fridge. Suppose we spread the jam evenly on a path between your grocer and your house, baste it with gasoline and lay a steel tape alongside with its metres interpreted as seconds. For some limited calculations, a square metre of this fuel and jam flavored real estate actually represents the time and energy difference between jam in your fridge and jam at the grocer. A grocery conglomerate might even use the model to strategiclly place new stores. But if we take the construction too far and try to attach fuel and jam properties to an ordinary square metre of real estate the model breaks down. GR is like that. The mass responsible for inertia is not evenly distributed so we have to take care about what we consider the "vacuum" or a pseudo-space and what we consider a representative region of real space. So, I don't pay too much attention to black hole physics unless the theorist lays enough foundation to demonstrate that he knows the difference in a jar of jam in the fridge and a jar of jam on the way to the fridge, because neither is well represented by a path covered with jam and gasoline. ;-) Sue... SR references: http://farside.ph.utexas.edu/teaching/em/lectures/node98.html http://farside.ph.utexas.edu/teaching/em/lectures/node50.html http://www.conformity.com/0102reflections.html GR references: http://nobelprize.org/nobel_prizes/physics/laureates/1921/einstein-lecture.html http://www.iisc.ernet.in/currsci/dec252005/2009.pdf http://www.bartleby.com/173/ Experimental Unruh Radiation? http://www.phys.lsu.edu/mog/mog17/node8.html > > > > "fitz" <zeusrdx@yahoo.com> wrote in message > > [quoted text clipped - 23 lines] > is used in the 1920 paper. The 1923 Gothenburg lecture offer some > insight why. The Tajmar / de Matos experiment is another clue. a) The Tajmar/de Matos experiment has yet to be published anywhere other than the arXiv and an ESA press release. For such groundbreaking work, some folks certaintly are dragging their feet. b) That is GR, the subject is about SR. Learn the difference. [snip word salad and irrelevant links] > > > > > "fitz" <zeusrdx@yahoo.com> wrote in message > > > [quoted text clipped - 27 lines] > other than the arXiv and an ESA press release. For such groundbreaking > work, some folks certaintly are dragging their feet. Indeed they are! << As of November 20, we are well into Phase III of the data analysis, which we expect to be concluded by late February, 2007. Whereas in Phases I and II, the focus was on individual gyro performance, during Phase III, the data from all four gyros is being integrated over the entire experiment. The results of this phase will be both individual and correlated changes in gyro spin axis orientation covering the entire 50-week experimental period for all four gyros. During this final analysis phase, we are continuing to pursue both geometric and algebraic interpretations of the data, which is enabling us to improve the accuracy of the results. >> http://einstein.stanford.edu/ Sue... > b) That is GR, the subject is about SR. Learn the difference. > > [snip word salad and irrelevant links] > > > > > > "fitz" <zeusrdx@yahoo.com> wrote in message > > > > [quoted text clipped - 41 lines] > results. >> > http://einstein.stanford.edu/ Oh look, another irrelevant link and text block. It looks like you do not know the difference between Tajmar's gravitational london moment experiment and LIGO. > Sue... > > > b) That is GR, the subject is about SR. Learn the difference. > > > > [snip word salad and irrelevant links] > > > > > > > "fitz" <zeusrdx@yahoo.com> wrote in message > > > > > [quoted text clipped - 46 lines] > It looks like you do not know the difference between Tajmar's > gravitational london moment experiment and LIGO. I told you not to take you nose out of Van der Pee Pee's behind or you'll get lost. LIGO is this way: http://www.ligo.caltech.edu/ Sue... > > Sue... > > > > > b) That is GR, the subject is about SR. Learn the difference. > > > > > > [snip word salad and irrelevant links] > > > > > > > > "fitz" <zeusrdx@yahoo.com> wrote in message > > > > > > [quoted text clipped - 50 lines] > behind or you'll get lost. LIGO is this way: > http://www.ligo.caltech.edu/ It isn't my fault you are *that* stupid. einstein.stanford.edu is the homepage of Einstein@home - the distributed computing application that processes data obtained from the GEO600 and LIGO gravitational wave observatories. > Sue... > [quoted text clipped - 3 lines] > > > > > > > > [snip word salad and irrelevant links] | When can we use special relativity? Never. No engineer will touch it with a barge pole with a sanity inspector in the end, and never has. | I'd like to have some comments on this. | | But I think the simple answer is that we can use special relativity as | long as no force fields are involved. | | Any comments? http://www.androcles01.pwp.blueyonder.co.uk/Rocket/Rocket.htm http://www.androcles01.pwp.blueyonder.co.uk/Smart/Smart.htm > When can we use special relativity? > [quoted text clipped - 6 lines] > > Fitz Use only when you want to pass your SR exam. > When can we use special relativity? SR is strictly valid only in a flat Lorentzian manifold with the topology of R^4. This of course is a very poor model of the world we inhabit. But physics is not math, and we often use approximations. SR is approximately valid when the curvature of the manifold is negligible over the region of interest compared to one's measurement accuracy. That is, if gravity is negligible (or compensated for), SR can probably be used. So, for instance, most tabletop experiments (for which the components are supported against gravity) can be analyzed using SR [#]. Virtually all elementary particle experiments can likewise be analyzed using SR (mainly because individual events have durations of only a few dozen nanoseconds). This is only a loose characterization, and when in doubt a proper GR computation or estimate should be performed. [#] But not all -- a fiber gyroscope fits on a table but can measure the rotation of the earth; the Eot-Wash apparatus fits on a table but is sensitive enough to respond to the gravity of the sun with exquisite precision. Tom Roberts >> When can we use special relativity? > [quoted text clipped - 16 lines] > apparatus fits on a table but is sensitive enough to > respond to the gravity of the sun with exquisite precision. Hmm.. about the fiber gyroscope, SRT is sufficient. And about Eot-Wash, that's neat! Do you have a reference? Thanks, Harald >> [#] But not all -- a fiber gyroscope fits on a table but >> can measure the rotation of the earth; the Eot-Wash >> apparatus fits on a table but is sensitive enough to >> respond to the gravity of the sun with exquisite precision. > > Hmm.. about the fiber gyroscope, SRT is sufficient. Yes. I realized that after posting. One must just realize that the tabletop is not an inertial frame to sufficient accuracy. > And about Eot-Wash, > that's neat! Do you have a reference? Look up Adelberger (from Washington University) in SPIRES, or possibly on arXiv.org. They built a modern version of the Eotvos experiment. Tom Roberts >>> [#] But not all -- a fiber gyroscope fits on a table but >>> can measure the rotation of the earth; the Eot-Wash [quoted text clipped - 12 lines] > > Tom Roberts Thanks :)) | > When can we use special relativity? | [quoted text clipped - 4 lines] | But physics is not math, and we often use approximations. SR is | approximately valid In other words, SR is f.cking useless. > When can we use special relativity? > [quoted text clipped - 6 lines] > > Fitz One simple answer: it was first used for accelerating electrons (would you say that "no force fields are involved"?). Harald > When can we use special relativity? > [quoted text clipped - 6 lines] > > Fitz Special relativity can be applied to any inertial frame, regardless of the external forces. | > When can we use special relativity? | > [quoted text clipped - 9 lines] | Special relativity can be applied to any inertial frame, regardless of | the external forces. Special relativity can be applied to any inertial brain, regardless of the external horses. > | > When can we use special relativity? > | > [quoted text clipped - 12 lines] > Special relativity can be applied to any inertial brain, regardless of > the external horses. Except when they have absolutely no clue about how to evaluate indeterminate fractions. You posted twice, fuckhead. | > | > When can we use special relativity? | > | > [quoted text clipped - 15 lines] | Except when they have absolutely no clue about how to evaluate | indeterminate fractions. > You posted twice, fuckhead. Twice, thrice, or even more. It's still way over your head. Have you ever actually learned how to evaluate indeterminant fractions? | > You posted twice, fuckhead. | | Twice, thrice, or even more. What the f.ck are you babbling about, snipper? > | > When can we use special relativity? > | > [quoted text clipped - 12 lines] > Special relativity can be applied to any inertial brain, regardless of > the external horses. Except when they have absolutely no clue about how to evaluate indeterminate fractions. | > | > When can we use special relativity? | > | > [quoted text clipped - 15 lines] | Except when they have absolutely no clue about how to evaluate | indeterminate fractions. The writer of the relativity FAQ's says: " SR is strictly valid only in a flat Lorentzian manifold with the topology of R^4. This of course is a very poor model of the world we inhabit. But physics is not math, and we often use approximations. SR is approximately valid" - Tom Roberts. http://en.wikipedia.org/wiki/Liar_paradox | Mike wrote: | > "Ficticous" has no place in physics. | Except that it _IS_ used. Because the various "fictitious forces" were | invented to maintain the FICTION that Newton's laws are valid in various | accelerated coordinates. | And, as I point out in another post in this thread, the world is NOT | Newtonian.... Redux: Fictitious Newtonian forces are not Newtonian. There is no liar paradox without a liar. Frankenstein's assistant, you are a fuckhead. Der alte Hexenmeister und Engineer Androcles Dumbledore B.A., M.Sc., Ph.D., Headmaster, hogwarts.physics school for zauberlehrlings. "One muggle's magic is another sorcerer's engineering" http://www.androcles01.pwp.blueyonder.co.uk/ |
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