A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: PD on 17 Feb 2010 16:47 On Feb 17, 2:38 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 17 Feb, 19:42, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 17, 12:51 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 17 Feb, 16:09, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 17, 8:46 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > I only agree with you that this is the burden of the expert in a > > > > > > constructed teacher-student environment, wherein there is a > > > > > > contractual arrangement that the student be taught something by the > > > > > > expert. > > > > > > > In an informal discussion group, and in particular a free one, there > > > > > > is no such arrangement and hence no such burden, although one might be > > > > > > undertaken on an ad hoc and completely voluntary basis. > > > > > > > You and I have already discussed this: that it is NOT the obligation > > > > > > of the expert to share knowledge. It is not true in law, medicine, > > > > > > plumbing, architecture, music, or engineering. Good musicians may > > > > > > offer lessons to students who want to learn, but that is usually under > > > > > > a contractual arrangement. It is the obligation of the expert to USE > > > > > > that knowledge to get work done. It is the obligation of a surgeon to > > > > > > USE his knowledge to make people well, but it is not his obligation to > > > > > > share his knowledge with others. > > > > > > As I say, there may be a moral difference here in some respects, but > > > > > I'm not really arguing whether or not there is a burden on an expert > > > > > to share knowledge. And indeed, if it is the intention of experts to > > > > > obfuscate a subject, strengthen their professional bargaining > > > > > positions, and exclude the majority, then it probably makes sense to > > > > > speak a different language. > > > > > But that isn't the only reason to use jargon, nor is it the reason > > > > that is used by scientists, AFAIK. > > > > I generally don't place too much emphasis on the explicit > > > justifications for certain behaviours. > > > > There is no doubt an argument that a specialised vocabulary increases > > > the efficiency of communication between professionals - but of course > > > the corollary to this is that a habitual reliance on such a vocabulary > > > dramatically increases the *inefficiency* of communicating with non- > > > professionals. > > > That's OK. Because the priority is given to professionals getting > > their work done, which places a higher premium on them communication > > with *each other* than it does on communication with nonprofessionals. > > You'll note the same thing in a hospital, where doctors and nurses are > > communicating in a highly specialized language that is very efficient > > for the purpose of making people healthier. > > Indeed. As I said, this argument no doubt can be made. > > > > However, even this justification often does not stand up to close > > > scrutiny. Many people (and this is not confined to any particular > > > profession) use specialised words where general ones will do, unusual > > > words where common ones will do, big words where smaller ones will do, > > > foreign words where native ones will do, complex constructs where > > > simple ones will do, to the extent that communication even with > > > educated professionals in the same field is made difficult. > > > I disagree that the communication between educated professionals is > > compromised as a result. At least in physics. You have evidence to > > support that contention? > > As I say, I wasn't talking specifically about physics. > > > > > > In these cases, whatever the real motivation for the vocabulary used, > > > it is not efficiency of communication (whether between professionals > > > or not). > > > > > > The point I'm making is that where "experts" are *purporting* to > > > > > desire productive communication with others who they know are not > > > > > experts, then they should recognise that this requires communication > > > > > skills, amongst which is the ability to converse in a common language. > > > > > Yes, but there's a tradeoff, and this is the tradeoff that is seen in > > > > popularizations. > > > > Popularization authors DO tend to try to use conventional language. > > > > But the drawback is that conventional language is looser and vaguer > > > > than the precise meanings used in physics. As a result, what is > > > > conveyed is also looser, vaguer, and more prone to misinterpretation, > > > > although it is more accessible. This limits the function of a > > > > popularization to TEACH the material. The saving strategy is then to > > > > use the popularization as an incentivizer to encourage the reader to > > > > embark on reading more carefully prepared materials, where more > > > > attention is paid to defining and using jargon. > > > > Perhaps. Personally I'm not thinking of popularisations, and I'm not > > > even thinking of physics in particular. > > > > But even to take two words that we've clashed over: "theory" and > > > "material". The fact is that you attribute a specialised meaning to > > > these words, and yet they are used as loosely within the profession as > > > outside it. > > > Document that, please. The definition I gave of both those terms is > > the one that is generally accepted in the physics profession. Do you > > have evidence otherwise? > > Yes, you provided the evidence yourself with "string theory", I believe I conveyed to you that, speaking to each other, physicists usually do not call "string theory" a theory, for precisely the reason that it fails to meet the criteria of a theory. However, physicists do use the term "string theory" in colloquial language for the sake of readers of popularizations and general public periodicals and TV shows. This is an attempt to make the subject accessible to that audience, though at the expense of accuracy, exactly as I alluded to earlier. > and > indeed you don't commit yourself any stronger than talking of the > "generally accepted definition". And yet, as I say, this convention is > regularly flouted, and it just becomes ludicrous to justify it in > terms of "well they are a minority", "that was a popularisation", etc. On the contrary, I just got through explaining to you that scientists DO use conventional language in popularizations, with full risk that it may introduce verbal ambiguity and lead to misconceptions, because the aim of popularization is not to teach but to inspire readers to read more carefully prepared materials suitable for teaching. > > As for "material", as I say, if you're discussing anything > philosophical then it alludes to "materialism", Philosophy is not physics. > and even philosophers > of science would accept this as a legitimate definition. I'm sorry, but physics and the philosophy of physics (or of science) do not share the same jargon, and for good reason. > To say that > people essentially can't use this word, because it has a specialised > meaning within the narrow field of experimental physics (if indeed it > does), is just absurd. Of course they can use the word. The word will just have a different meaning in the different context. Just as "materialism" means something different in the philosophy of science and in the philosophy of economics. > > > > There can be no argument that the use of these words > > > increases the efficiency of communication with professionals, and the > > > ensuing dispute over their use here increased the inefficiency of > > > communication dramatically. > > > I've already explained to you, using the example of "mammal", why it > > is preferred to insist on the proper meaning of that word, even if a > > layperson may confuse it to mean tetrapod land animals. > > Broadly I agree that words should be used within their correct > definitions, and this is one situation where a correction would be in > order. > > But there is no argument that words, like "theory", should be given an > unwarranted narrower definition than their legitimate everyday > meaning, simply because one is talking to a specialist - unless, of > course, it is expressly stipulated that the narrower definition will > be used for the time being for the sake of necessary accuracy. I disagree. In a teaching environment, that is EXACTLY the stipulation that is made, over and over again as the terms come up in the course of study. "Momentum", "velocity", "energy", "heat", "field", "potential", "mass" are all examples of terms that are very carefully segregated from conventional usage in the context of physics. As an example, something that is going around in a circle at a constant 20 mph is *painfully* explained not to have constant velocity at all, regardless whether you're used to thinking of 20 mph as being a measure of velocity. Now, if you're not in a teaching environment but an open discussion forum, then such ground rules are not necessarily assumed, even if it would be more efficient. You get what you pay for. > > Of course, false friends like "rotation" are perfectly acceptable, so > long as the expert acknowledges that its specialised meaning is either > broader in some sense, or even totally unfamiliar, relative to the > everyday meaning.
From: PD on 17 Feb 2010 16:50 On Feb 17, 2:40 pm, Paul Stowe <theaether...(a)gmail.com> wrote: > On Feb 17, 11:44 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 17, 12:34 pm, PaulStowe<theaether...(a)gmail.com> wrote: > > > > On Feb 17, 10:24 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 17, 11:39 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > On 17 Feb, 16:00, PaulStowe<theaether...(a)gmail.com> wrote: > > > > > > > On Feb 17, 7:04 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > > As we discussed earlier, it may be that we are only AWARE of four > > > > > > > > dimensions. It may well be that there are more. Then the way to > > > > > > > > entertain this notion is to ask the question, how would something that > > > > > > > > is only AWARE of two dimensions become convinced that there is a third > > > > > > > > dimension? This turns out to be very answerable. > > > > > > > > I'm afraid that was not my conclusion. As I've said, these > > > > > > > possibilities only seem credible to those who already hold them to be > > > > > > > credible. > > > > > > > What I've seen here, and even in some books, is a vague improper use > > > > > > of the term dimension. From what I can tell, the term is strictly as > > > > > > used, a mathematical concept. See: > > > > > > >http://mathworld.wolfram.com/Dimension.html > > > > > > > It is often confused with the concept of physical properties such as > > > > > > mass, length, time, charge. Since two of these (length and time) are > > > > > > modeled using geometrical dimensionality this leads to the confusion. > > > > > > Adding further to this is the unitary systems we assign to the > > > > > > physical properties (kilogram, meter, second, Coulomb, ... etc.). A > > > > > > dimension has no physical existence and a physical property has no > > > > > > inherent unitary values, we must combine these concepts to make, > > > > > > quantify, and describe physical systems and processes. > > > > > > > As time goes on we get more creative on assigning the term. In > > > > > > relativity where we have, > > > > > > > dx^2 + dy^2 + dz^2 - ds^2 = 0 > > > > > > > The s (ct) term isn't itself a simply point, it's a computed > > > > > > projection of a destination (point) dependent upon a physical > > > > > > property, the speed c. To have strict orthogonal axes c must remain > > > > > > constant over infinite space. In turn, if this were true, there would > > > > > > be no need for the hydrodynamical equation of General relativity. In > > > > > > fact, all observational evidence to date supports the fact that, by > > > > > > strict definition of the term dimension only three primal or actual > > > > > > dimensions exist and time is 'mapped' into pseudo forth using the > > > > > > physical property of c to do so. > > > > > > Indeed. Some people look at you funny when you talk of something like > > > > > a "five-dimensional database". > > > > > > I'm convinced that the essential need for the 4th dimension in > > > > > relativity, and the significance of 'c', is simply because > > > > > electromagnetic propagation delays have become practically > > > > > significant. > > > > > Then you are erroneously convinced. > > > > You may recall that we were discussing how to determine simultaneity > > > > when those propagation delays are fully accounted for. > > > > Define 'fully accounted for'. Did you include the physical length > > > contraction in that? > > > Yes! This is news to you? > > > > WSo does fully accounted for account for that? > > > WSo? > > Knock off the erroneous W... > > So, does "fully accounted for" account for that? Yes. Already answered. > > > > > > > > Before the end of the 19th century and the development of > > > > > electromagnetic communications over long distances, electromagnetic > > > > > effects for all practical purposes moved instantaneously. > > > > > And that's just flat wrong. Well before the 19th century, the > > > > aberration of the orbit of Jupiter was *known* to be due to the > > > > propagation delay of light. > > > > Yes, but that was an abstraction, not associated with the fundamental > > > properties of 'ponderous matter' systems. > > > So? Does one have to presume a medium or an absence of a medium to > > both acknowledge and account for a finite propagation delay of light? > > > > He's not wrong, physicists > > > did not account for propagation delays UNTIL! the MMX slapped them in > > > the face. > > > That is simply historically false. > > Propagation delays were known, YES! But, the universal application as > applied to constituting physical systems, NO! Universal application?? Who said anything about universal application? Even if a rule is right and general does not mean that it is universally used in every application, when a rule of thumb or a handy approximation will serve for the purpose. > Hell modern atomic > theory wasn't even there until the end of the 19th century, much less > 'thinking about how EM propagation delays affected bound mundane > material systems. I think you're being deliberately annal here since > you should know full well what STE & I are talking 'in context' about > here. Then illuminate me about the context Ste is referring to here.
From: Inertial on 17 Feb 2010 16:50 "kenseto" <kenseto(a)erinet.com> wrote in message news:e23daec9-0ab0-4a5f-b7ce-fd4d34ff622d(a)w31g2000yqk.googlegroups.com... > On Feb 17, 4:17 pm, "Inertial" <relativ...(a)rest.com> wrote: >> "kenseto" <kens...(a)erinet.com> wrote in message >> >> news:7c117076-4a6e-4d51-ab62-c3014a7e2559(a)z11g2000yqz.googlegroups.com... >> >> >> >> >> >> > On Feb 16, 6:42 pm, "Inertial" <relativ...(a)rest.com> wrote: >> >> "PD" <thedraperfam...(a)gmail.com> wrote in message >> >> >>news:da09c070-e346-42f6-a55f-cabf519d20dc(a)k36g2000prb.googlegroups.com... >> >> >> > On Feb 16, 5:17 pm, "Inertial" <relativ...(a)rest.com> wrote: >> >> >> "PD" <thedraperfam...(a)gmail.com> wrote in message >> >> >> >>news:995b34f4-be02-48bb-b9db-463e3437283a(a)j27g2000yqn.googlegroups.com... >> >> >> >> > On Feb 16, 12:57 pm, kenseto <kens...(a)erinet.com> wrote: >> >> >> >> On Feb 16, 1:46 pm, PD <thedraperfam...(a)gmail.com> wrote: >> >> >> >> >> > Picking and choosing your definitions, Ken? >> >> >> >> > Look at the definitions I highlighted for you. >> >> >> >> > Look at your freshman physics textbook. Does it tell you that >> >> >> >> > the >> >> >> >> > electric field is not physical? >> >> >> >> >> In the past you insisted that length contraction in SR is >> >> >> >> physical >> >> >> >> and >> >> >> >> at that time you think that physical means material. >> >> >> >> > No, sir, I *never* said length contraction was material. I said >> >> >> > it >> >> >> > was >> >> >> > PHYSICAL. >> >> >> >> >> You even >> >> >> >> suggested that length contraction can be measured directly by >> >> >> >> shooting >> >> >> >> lasers from the ends of a moving ruler to the rest frame of the >> >> >> >> observer. >> >> >> >> > Yes, it is MEASURABLE. Physical things are measurable. >> >> >> > Energy is MEASURABLE, it is not material. >> >> >> > Magnetic fields are MEASURABLE, they are not material. >> >> >> > Radio waves are MEASURABLE, they are not material. >> >> >> >> >> So you see you think that length contraction in SR is >> >> >> >> material. >> >> >> >> > No, it is MEASURABLE. It is not material. >> >> >> >> >> Also your SR brother Inertial said in this thread that >> >> >> >> contraction >> >> >> >> in >> >> >> >> SR means that the atoms get closer....this means material >> >> >> >> contraction. >> >> >> >> > Ken, rather than desperately trying to gather excuses to support >> >> >> > your >> >> >> > mistaken impression, why don't you just take another look at the >> >> >> > correct definitions for physical that I've already shown you? Why >> >> >> > don't you reread your freshman physics text again, and check >> >> >> > whether >> >> >> > it says the electric field is not physical? If you've made a >> >> >> > small >> >> >> > mistake, then CORRECT IT and move on. If you cannot ever correct >> >> >> > a >> >> >> > small mistake, you'll never get out of square one. You'll spend >> >> >> > all >> >> >> > your time searching newsgroups for support for your mistake. >> >> >> >> Note that the atoms in a length-contracted rod are physically >> >> >> closer >> >> >> together, as measured in the relatively moving inertial frame. In >> >> >> that >> >> >> frame the material that makes up the rod is fitting within a >> >> >> shorter >> >> >> distance (ie compressed). >> >> >> > Well, I know what you're saying, but I'd be very careful about >> >> > terminology here to avoid confusion. Seto thinks of compression as >> >> > being solely the effect of a material interaction, such as a >> >> > compressive *force* or perhaps a low temperature bath. That's not >> >> > what's going on here. So yes, the pole is shorter and since no atoms >> >> > have been lost, then the atoms have a different length, but this >> >> > does >> >> > not imply anything squeezing on them (even if Seto can't imagine it >> >> > happening any other way). >> >> >> I didn't say they were squeezed .. I said they were closer together. >> >> > You didn't say that they were squeezed and I didn't interpret that >> > they were squeezed. But when you said that the atoms are closer >> > together I interpreted that the pole is materially really gotten >> > shorter...iow it is not just a geometic projection effect. >> >> It is a geometric projection / rotation. And that projection has >> physical >> effects. Just like the geometric projection / rotation of a tilted >> ladder >> has the physical effect that it is not as tall and can fit thru a >> doorway. > > So are you saying that when you tilt the ladder the atoms in the > ladder get a little closer? Where did I say that? But in terms of height .. yes, the same number of atoms is occupying less height. > I don't think so. You just don't think .. at least not rationally and consistently. You seem to think it is ok for a tilted ladder to fit physically thru a doorway, and seem to agree that the tilting of the ladder is a physical change in the combined system of the ladder + doorway (eg if you tilt it toward the door, the top to the ladder gets physically closer to the doorway) And that tilting is "just" a geometric operation. Yet when it comes to a similar geometric operation (but in a different axis) that is called commonly 'length contraction', you deny that there is any physical effect at all (ie that length contraction does not contract length). How can you hold two such contradictory views and then go complaining about non-existent contradictions in SR (and the position of those trying to explain it to you). Answer: You just don't think .. at least not rationally and consistently.
From: PD on 17 Feb 2010 16:50 On Feb 17, 3:22 pm, kenseto <kens...(a)erinet.com> wrote: > On Feb 17, 4:17 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > > > "kenseto" <kens...(a)erinet.com> wrote in message > > >news:7c117076-4a6e-4d51-ab62-c3014a7e2559(a)z11g2000yqz.googlegroups.com.... > > > > On Feb 16, 6:42 pm, "Inertial" <relativ...(a)rest.com> wrote: > > >> "PD" <thedraperfam...(a)gmail.com> wrote in message > > > >>news:da09c070-e346-42f6-a55f-cabf519d20dc(a)k36g2000prb.googlegroups.com... > > > >> > On Feb 16, 5:17 pm, "Inertial" <relativ...(a)rest.com> wrote: > > >> >> "PD" <thedraperfam...(a)gmail.com> wrote in message > > > >> >>news:995b34f4-be02-48bb-b9db-463e3437283a(a)j27g2000yqn.googlegroups..com... > > > >> >> > On Feb 16, 12:57 pm, kenseto <kens...(a)erinet.com> wrote: > > >> >> >> On Feb 16, 1:46 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > >> >> >> > Picking and choosing your definitions, Ken? > > >> >> >> > Look at the definitions I highlighted for you. > > >> >> >> > Look at your freshman physics textbook. Does it tell you that the > > >> >> >> > electric field is not physical? > > > >> >> >> In the past you insisted that length contraction in SR is physical > > >> >> >> and > > >> >> >> at that time you think that physical means material. > > > >> >> > No, sir, I *never* said length contraction was material. I said it > > >> >> > was > > >> >> > PHYSICAL. > > > >> >> >> You even > > >> >> >> suggested that length contraction can be measured directly by > > >> >> >> shooting > > >> >> >> lasers from the ends of a moving ruler to the rest frame of the > > >> >> >> observer. > > > >> >> > Yes, it is MEASURABLE. Physical things are measurable. > > >> >> > Energy is MEASURABLE, it is not material. > > >> >> > Magnetic fields are MEASURABLE, they are not material. > > >> >> > Radio waves are MEASURABLE, they are not material. > > > >> >> >> So you see you think that length contraction in SR is > > >> >> >> material. > > > >> >> > No, it is MEASURABLE. It is not material. > > > >> >> >> Also your SR brother Inertial said in this thread that contraction > > >> >> >> in > > >> >> >> SR means that the atoms get closer....this means material > > >> >> >> contraction. > > > >> >> > Ken, rather than desperately trying to gather excuses to support > > >> >> > your > > >> >> > mistaken impression, why don't you just take another look at the > > >> >> > correct definitions for physical that I've already shown you? Why > > >> >> > don't you reread your freshman physics text again, and check whether > > >> >> > it says the electric field is not physical? If you've made a small > > >> >> > mistake, then CORRECT IT and move on. If you cannot ever correct a > > >> >> > small mistake, you'll never get out of square one. You'll spend all > > >> >> > your time searching newsgroups for support for your mistake. > > > >> >> Note that the atoms in a length-contracted rod are physically closer > > >> >> together, as measured in the relatively moving inertial frame. In > > >> >> that > > >> >> frame the material that makes up the rod is fitting within a shorter > > >> >> distance (ie compressed). > > > >> > Well, I know what you're saying, but I'd be very careful about > > >> > terminology here to avoid confusion. Seto thinks of compression as > > >> > being solely the effect of a material interaction, such as a > > >> > compressive *force* or perhaps a low temperature bath. That's not > > >> > what's going on here. So yes, the pole is shorter and since no atoms > > >> > have been lost, then the atoms have a different length, but this does > > >> > not imply anything squeezing on them (even if Seto can't imagine it > > >> > happening any other way). > > > >> I didn't say they were squeezed .. I said they were closer together. > > > > You didn't say that they were squeezed and I didn't interpret that > > > they were squeezed. But when you said that the atoms are closer > > > together I interpreted that the pole is materially really gotten > > > shorter...iow it is not just a geometic projection effect. > > > It is a geometric projection / rotation. And that projection has physical > > effects. Just like the geometric projection / rotation of a tilted ladder > > has the physical effect that it is not as tall and can fit thru a doorway. > > So are you saying that when you tilt the ladder the atoms in the > ladder get a little closer? I don't think so. They do along the plane of the doorway, yes! > > Ken Seto > > > > > I don't see why you find this so confusing.- Hide quoted text - > > > - Show quoted text - > >
From: PD on 17 Feb 2010 16:55
On Feb 17, 3:50 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 17, 3:22 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > On Feb 17, 4:17 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > > "kenseto" <kens...(a)erinet.com> wrote in message > > > >news:7c117076-4a6e-4d51-ab62-c3014a7e2559(a)z11g2000yqz.googlegroups.com.... > > > > > On Feb 16, 6:42 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > >> "PD" <thedraperfam...(a)gmail.com> wrote in message > > > > >>news:da09c070-e346-42f6-a55f-cabf519d20dc(a)k36g2000prb.googlegroups.com... > > > > >> > On Feb 16, 5:17 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > >> >> "PD" <thedraperfam...(a)gmail.com> wrote in message > > > > >> >>news:995b34f4-be02-48bb-b9db-463e3437283a(a)j27g2000yqn.googlegroups.com... > > > > >> >> > On Feb 16, 12:57 pm, kenseto <kens...(a)erinet.com> wrote: > > > >> >> >> On Feb 16, 1:46 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > >> >> >> > Picking and choosing your definitions, Ken? > > > >> >> >> > Look at the definitions I highlighted for you. > > > >> >> >> > Look at your freshman physics textbook. Does it tell you that the > > > >> >> >> > electric field is not physical? > > > > >> >> >> In the past you insisted that length contraction in SR is physical > > > >> >> >> and > > > >> >> >> at that time you think that physical means material. > > > > >> >> > No, sir, I *never* said length contraction was material. I said it > > > >> >> > was > > > >> >> > PHYSICAL. > > > > >> >> >> You even > > > >> >> >> suggested that length contraction can be measured directly by > > > >> >> >> shooting > > > >> >> >> lasers from the ends of a moving ruler to the rest frame of the > > > >> >> >> observer. > > > > >> >> > Yes, it is MEASURABLE. Physical things are measurable. > > > >> >> > Energy is MEASURABLE, it is not material. > > > >> >> > Magnetic fields are MEASURABLE, they are not material. > > > >> >> > Radio waves are MEASURABLE, they are not material. > > > > >> >> >> So you see you think that length contraction in SR is > > > >> >> >> material. > > > > >> >> > No, it is MEASURABLE. It is not material. > > > > >> >> >> Also your SR brother Inertial said in this thread that contraction > > > >> >> >> in > > > >> >> >> SR means that the atoms get closer....this means material > > > >> >> >> contraction. > > > > >> >> > Ken, rather than desperately trying to gather excuses to support > > > >> >> > your > > > >> >> > mistaken impression, why don't you just take another look at the > > > >> >> > correct definitions for physical that I've already shown you? Why > > > >> >> > don't you reread your freshman physics text again, and check whether > > > >> >> > it says the electric field is not physical? If you've made a small > > > >> >> > mistake, then CORRECT IT and move on. If you cannot ever correct a > > > >> >> > small mistake, you'll never get out of square one. You'll spend all > > > >> >> > your time searching newsgroups for support for your mistake. > > > > >> >> Note that the atoms in a length-contracted rod are physically closer > > > >> >> together, as measured in the relatively moving inertial frame. In > > > >> >> that > > > >> >> frame the material that makes up the rod is fitting within a shorter > > > >> >> distance (ie compressed). > > > > >> > Well, I know what you're saying, but I'd be very careful about > > > >> > terminology here to avoid confusion. Seto thinks of compression as > > > >> > being solely the effect of a material interaction, such as a > > > >> > compressive *force* or perhaps a low temperature bath. That's not > > > >> > what's going on here. So yes, the pole is shorter and since no atoms > > > >> > have been lost, then the atoms have a different length, but this does > > > >> > not imply anything squeezing on them (even if Seto can't imagine it > > > >> > happening any other way). > > > > >> I didn't say they were squeezed .. I said they were closer together. > > > > > You didn't say that they were squeezed and I didn't interpret that > > > > they were squeezed. But when you said that the atoms are closer > > > > together I interpreted that the pole is materially really gotten > > > > shorter...iow it is not just a geometic projection effect. > > > > It is a geometric projection / rotation. And that projection has physical > > > effects. Just like the geometric projection / rotation of a tilted ladder > > > has the physical effect that it is not as tall and can fit thru a doorway. > > > So are you saying that when you tilt the ladder the atoms in the > > ladder get a little closer? I don't think so. > > They do along the plane of the doorway, yes! Ken, this should be obvious! A ladder has 9.6E26 atoms along its length. Its length measured with a ruler that is lain parallel to the ladder is 12 feet. This means there are 8.0E25 atoms per foot by this measurement. Now you tip the ladder so that it will fit through a doorway that is 8 feet high. No atoms have disappeared from the ladder when you tip it, so all 9.6E26 atoms in a line in the ladder still have to get through the doorway. This means there are 1.2E26 atoms per foot by this measurement. Yes indeed, more atoms per foot! It's OBVIOUS! > > > > > Ken Seto > > > > I don't see why you find this so confusing.- Hide quoted text - > > > > - Show quoted text - > > |