A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Paul Stowe on 2 Mar 2010 20:53 On Mar 2, 3:45 pm, Tom Roberts <tjroberts...(a)sbcglobal.net> wrote: > PaulStowewrote: > > In Lorentz's model > > the local invariance is just as much universal as it is in SR. > > Not true. The ether is at rest in a specific inertial frame. That is an > essential part of LET, and it violates Lorentz invariance at a very fundamental > level in LET. How? How does it violate the Lorentz Group? In fact, in SR every local frame can be 'declared' at rest. There is neither an observable or mathematical difference for the actual aether rest frame. > > In > > fact, his model's physical basis demands it. > > No! his physical basis requires the ether to be at rest in some specific > inertial frame. So what? > > Moreover, his model > > naturally accepts the fact that light speed can vary from one region > > to another since it is the resultant of density and compressibility. > > His model, as presented in 1904, does not include this at all. You seem to be > confusing your personal hopes and dreams with what Lorentz wrote. Does it not include and assume an aether? The aether was accept as a physical medium as such, like all mediums it would has a density and compressibility (inverse modulus). It is inherited as part and pacel of declaring the aether. > Tom Roberts Paul Stowe
From: Inertial on 2 Mar 2010 21:02 "Peter Webb" <webbfamily(a)DIESPAMDIEoptusnet.com.au> wrote in message news:4b8dc20b$0$11181$afc38c87(a)news.optusnet.com.au... > Evolution is not accepted because it agrees with experimental data, and > that has nothing to do why people believe its true? I think you meant: Evolution *is* accepted because it agrees with experimental data Either that or your comment doesn't make sense to me :):)
From: Peter Webb on 2 Mar 2010 21:02 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:c122829f-64e2-4568-a3c8-56796b4c6895(a)g11g2000yqe.googlegroups.com... > On 2 Mar, 09:15, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: >> And hence, when I say I want to discuss things instead >> of just going off and reading a book, it's not because I'm being >> awkward or just want to sound off cranky ideas to an audience, but >> because I genuinely apprehend that the interactive discussion is >> necessary for the questions at hand. >> >> _____________________________ >> That is obviously not true. You don't ask questions trying to learn. You >> state your open disbelief that SR is true, > > Peter, I can only put you to the proof of showing where I said I > disbelieved SR. > That is incoherent. You say you are here to learn about SR. Do you believe SR is true? > > >> you constantly dispute reasonable explanations, > > Because the explanations disputed are not, in fact, reasonable. > To you. Reasonable to everybody else, it appears. > > >> you criticise science as a whole when you are >> pretending to try and learn it, > > I have only "criticised" science in the sense of objecting to the > patent inaccuracies, or even mendacities, that are perpetuated by some > who claim to follow science. That is not true. That is not the only criticism, and in fact you have never made that objection before. What are the patent inaccuracies and mendacities that you refer to, and what scientists did these?
From: Bruce Richmond on 2 Mar 2010 21:12 On Mar 2, 11:59 am, PD <thedraperfam...(a)gmail.com> wrote: > On Mar 2, 5:53 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 1 Mar, 23:49, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Mar 1, 5:33 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > secondly > > > > > > the degree to which opponents seem to be unclear about the conceptual/ > > > > > > qualitative basis of SR, > > > > > > I'd be careful about this. It may be that they are clear on the > > > > > conceptual/qualitative basis, but are declining to present it to you, > > > > > out of a personal preference for using the clarity and condensed > > > > > efficiency of mathematics. This unwillingness to cater to your > > > > > pedagogical needs should not be construed as their being unclear. > > > > > Paul, there is nothing "clear and efficient" about mathematical > > > > statements made without any indication as to their meaning. > > > > Yes, there is, for people who have learned that skill. This is one of > > > the reasons why the skill is so important for physicists to learn -- > > > because it so promotes clear and efficient communication among those > > > so trained. > > > Not, as I say, if the discussion is at a qualitative, conceptual > > level. > > And I've told you this is wrong. Because.... > > > Maths in that event becomes utterly useless, because it does > > not describe phenomena qualitatively - in fact it quantifies phenomena > > that have already been (explicitly or implicitly) described > > qualitatively. > > ... there is much qualitative information in the math itself, which is > obvious to people who are experience in reading math. I've told you > repeatedly that there is physical content in the mathematical > formulation of physics, and I've even given you a few examples in the > past, which you admitted you had not appreciated. > > > > > > Likewise, auto mechanics is so much simpler for people who have the > > > right toolbox and know how to use them, and auto mechanics are not > > > very inclined to teach someone how to service cars if all they know > > > how to use is a spanner and a screwdriver. > > > It really depends. > > Good luck with that. > > > > > > > > > > > The > > > > argument here is not about the mathematical form of SR, but about its > > > > physical meaning. I'm willing to concede that certain posters may be > > > > unaccustomed to discussing anything but maths, and may therefore find > > > > it difficult to articulate the relevant information, and that's an > > > > allowance that must be made, but that's not a preference for being > > > > "clear and efficient" - in fact the effect is to make much of what is > > > > written utterly obscure and ineffectual.' > > > > For those that are not so trained, it IS utterly obscure and > > > ineffectual. But then accomplishing the task of explanation *overall* > > > is optimized if you do learn that skill, because the gain in > > > efficiency following learning the skill more than offsets the burden > > > of learning the skill in the first place. It's like learning how to > > > play music and the requirement that you read music. You CAN learn > > > musical pieces without learning how to read music -- it's just not > > > recommended. > > > More to the point, one can understand the principles of music without > > reading music or being able to play an instrument with any real > > aptitude. > > Yes, but laboriously and poorly, and the teacher may be quite > irritated at having to explain the principles of music without the > benefit of being able to point to a sheet of music and say, "See? Here > is where the minor third is resolved over the course of four measures, > accompanied a half-measure behind by this fugue passage." > > Again, it is *possible* to understand physics qualitatively without > the math. But laboriously and poorly, and teachers will find it less > than efficient to teach that way, when it would be much easier to > produce the desired result after some skill training. Your reluctance > to spend the effort on the skill notwithstanding. > > > The discussions here have followed a script something like > > "Q: how does the instrument make the sound. A: Oh, well, I can't > > explain that unless you know how to read music." The problem is that > > there seems to be some disagreement about whether knowing maths is > > essential to describing physics qualitatively, and it is my contention > > that it isn't. > > > To explain why supposed experts here take a different view, I can only > > conclude that they don't really understand the nature of my questions > > - the evidence to support this conclusion is, for example, the fact > > that no one here seems to know immediately what the word "physical" > > means when I and others have used the word. This makes me less > > confident in trusting those who say that learning the maths will > > answer my questions. > > That's an erroneous conclusion. > > > > > > I understand that you JUST DON'T WANT to learn that skill. > > > It's that I'm not interested in learning the skill for its own sake, > > or worse on the false pretense that it will actually answer any > > questions. > > > > However, > > > this then asks people to use a relatively inefficient means to > > > communicate the physics to accommodate this disability. > > > No. > > Yes. > > > > > > > > > > > > > and thirdly the preconceptions and > > > > > > psychological style of many posters. > > > > > > In other words, your basis for deciding what is correct depends on the > > > > > manners of the people you discuss it with? > > > > > No, I'm saying some of the personalities that one must grapple with > > > > here are not the sort of personalities who make good discussion > > > > partners. Indeed many posters seem to have preconceptions or styles > > > > that are designed to avoid or deter productive discussion and sharing > > > > of knowledge. > > > > Indeed. I think you'll find that the university environment, where > > > discussion partners have placed themselves in the position of being > > > more friendly and accommodating, is more productive. > > > That may well be the case, but inevitably I don't have casual access > > to a university environment, or the inclination to follow a course of > > study in physics, most of which I would have absolutely no interest > > in. > > That's fine. But that does not imply that you should expect to get > what you want, avoiding the unpleasantnesses and inconveniences, in a > venue that you choose, for free. > > > > > > > > > > > > I'm sorry, but I've got a lot of classroom experience that shows that > > > > > this is simply a bogus expectation. I can set up a series of simple > > > > > experiments on a daily basis in class where I can display all the > > > > > elements of the experiment and show them plainly how the simple set-up > > > > > is put together, and then I can ask everyone in the class what their > > > > > intuition tells them will happen, and at least have of them will get > > > > > it wrong, which the subsequent observation will show. > > > > > Yes, because there is a discrepancy between intuition and observation. > > > > But as I say, there is no room for a discrepancy - in the sense of > > > > "this town ain't big enough for the both of us" - and inevitably > > > > intuition is the one which must leave town (which in practice means > > > > either refining an existing intuition, or overhauling it to a greater > > > > or lesser degree). > > > > Exactly. And so when you say that what I described just isn't > > > "realistic" according to your intuition, then it is your intuition > > > that needs to be overhauled. > > > Just because someone else *says* something is irreconcilable with > > intuition, does not mean intuition must be immediately overhauled. > > I agree! One needs to either see it experimentally for oneself, or to > become thoroughly acquainted with the experimental work done by > others! That is the essential and indispensable ingredient in being > convinced that one's intuition is just off the mark, and nothing else > will substitute. > > > > > > > If > > I had done that, for example, when people said "what is simultaneous > > in one frame is not simultaneous in another", then I'd have thrown > > away perfectly legitimate intuitions which said that this statement > > was wrong. > > > > > > Yes, I see what you are thinking of. And it is true that IN THIS CASE, > > > > > E1 and E2 will be viewed as simultaneous by both observers. I do > > > > > concede this. > > > > > > This is not the situation we were discussing before, however. > > > > > I wasn't talking about the train case. I was talking about this > > > > specific scenario, which I had posted before, and which last time > > > > indeed you conceded without fuss. > > > > > But for some reason everyone, including you apparently[1] but > > > > certainly not limited to just you, seemed to go back to talking about > > > > "what is simultaneous in one frame is not simultaneous in another", > > > > when in fact the veracity of that statement is contingent on the > > > > circumstances, and there are in fact cases (i.e. the one above) where > > > > what is simultaneous in one frame *is* simultaneous in another. It is > > > > that contingency that allows reconciliation with my intuitions. > > > > > [1] I quote you from above "It is very much true in SR that two > > > > spatially separated events that are simultaneous in one frame are not > > > > simultaneous in another frame moving relative to the first". > > > > I've already noted to you that the statement I made is not accurate > > > and needs revision, which I'm happy to do. > > > That's fair enough, but hence I've found that my intuitions were, at > > least in this respect, in agreement with your understanding all along. > > > Now that is cleared up, what I'm still not clear about is whether this > > non-simultaneity is a mere function of finite propagation speeds, or > > something else. > > It is not a function of finite propagation speeds, this we know, > because we took into account the finite propagation speeds in our > procedure for determining simultaneity/nonsimultaneity. Do you not > remember that? I beg to differ. It is not a "mere" or "simple" function of finite propagation speed, but it *is* a function of it IMO. RoS only took it into account by allowing us to use different time coordinates in each frame. If the speed of light was infinite there would be no RoS. - Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: Peter Webb on 2 Mar 2010 21:15
Next, what is the fundamental cause (confining ourselves to SR) of this non-simultaneity? As I say, as far as I can tell, it's a simple function of the finite speed of propagation. But I'm told that it isn't, so I need to know on what grounds a simple propagation explanation does not suffice. ________________________________ Hey! You asked a question about SR ! Far out! The ultimate reason (or, more accurately "an" ultimate reason) is that the speed of light is the same in all inertial reference frames, and does not depend on the speeds of two different observers. This makes the propagation delay a function of the frame of reference you pick, and not a function of the underlying dynamics. Any book on SR will explain this, and in fact I believe that Einstein discussed this in his 1905 paper. Have you read it? As to why the speed of light is the same in all inertial reference frames, this is because of Maxwell's eqns, a whole lot earlier than SR, and the primary motivator for the MM experiment. I tried to give you an informal, non-mathematical description of why Maxwell's eqns produce a speed of light that is constant in all reference frames, but you said you didn't understand. If you would like to visit a webpage or buy a book on Maxwell's eqns, I would be happy to answer any questions that you have about them that you don't understand. Please provide the exact quote in context of whatever it is that isn't clear, and I will see what I can do to help. |