A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: PD on 1 Mar 2010 18:49 On Mar 1, 5:33 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 1 Mar, 15:48, PD <thedraperfam...(a)gmail.com> wrote: > > > On Feb 28, 12:54 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > [... big snip ...] > > > > 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. 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. > 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. I understand that you JUST DON'T WANT to learn that skill. However, this then asks people to use a relatively inefficient means to communicate the physics to accommodate this disability. > > > > 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. > > > > > > > > If > > > > > such a thing appears to happen, then it is obviously an artefact of > > > > > subjective observation. > > > > > I disagree. In science, if there is a conflict between experimental > > > > observation and intuition, then it is *intuition* that becomes > > > > suspect, not the experimental result, especially if the latter is > > > > confirmed independently and by complementary means. > > > > I'm afraid there is no room for a discrepancy between intuition and > > > observation. > > > 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. > > > > > > > > > > > Your disbelief of SR stems from the fact that you don't understand it. > > > > > > > > My disbelief, really, stems from the blatant lack of conceptual > > > > > > > understanding of the theory. I mean, as I repeatedly point out, I > > > > > > > don't know a single equation of relativity, and yet I can root out the > > > > > > > conceptual contradictions immediately when people here have a crack at > > > > > > > making meaningful qualitative statements in SR. The classic example, > > > > > > > of course, was Paul's contention that "what is simultaneous in one > > > > > > > frame can never be simultaneous in another", which of course isn't > > > > > > > true according to SR. > > > > > > > I'm sorry? 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. > > > > > > But I contradicted that when I pointed out that two observers can be > > > > > moving relative to each other, and yet undoubtedly events can be > > > > > simultaneous for both. > > > > > Not spatially separated ones, no. > > > > I'm confused, because I thought we previously agreed that two > > > observers travelling along the same axis, maintaining equidistance > > > from both events at all times, would both report each event as > > > simultaneous with the other event. > > > Not quite. What we said was defined what it means for two spatially > > separated events to be simultaneous, by a procedure. The same > > procedure can similarly tell you when two events are not simultaneous. > > > Where we left off the discussion of the case I presented is that for > > the same pair of events, one observer (which satisfies all the > > criteria of being equidistant between the events and so on) concludes > > correctly from his observations that the two events are simultaneous, > > and the other observer (which also satisfies the same criteria) > > concludes correctly that the two events are not simultaneous. > > > We were about to show how this is completely consistent with the laws > > of physics. > > Then you were labouring the point, because I already held this to be > consistent with the laws of physics - as evidenced by my existing > understanding, where I was able to identify a situation where > simultaneity *is* present for both frames, because the changes in > relative distances from each event are kept symmetrical for both > observers. Yes, you did. > You've presented a situation where the changes in relative > distances are not kept symmetrical, No, they're still symmetrical. We hadn't gotten that far. > so simultaneity changes, but > that's not inconsistent with my existing intuitions. > > > > > > And moreover, if they not only both > > > maintained equidistance from both events, but if they maintained a > > > separation which was equal for both observers (which, if both > > > observers are moving relative to each other, requires either a > > > collision course between observers, or travel in diametrically > > > opposite directions), then there is no question that the signals are > > > received simultaneously. > > > > Illustration: > > > > E1 > > > > -------- > > > > E2 > > > > The line represents the line between events E1 and E2, along which the > > > observers may move while always reporting both events to be > > > simultaneous. > > > 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.
From: Ste on 1 Mar 2010 18:53 On 1 Mar, 15:50, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 28, 1:05 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > On 27 Feb, 15:58, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Feb 26, 6:59 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > There's a variety of things one can do (and are done). > > > > > 1) Explore other candidates, though at a level that is commensurate > > > > > with risk-benefit analysis of the effort involved. > > > > > 2) Continue to do other tests of this model vs other models to see > > > > > where the 5% might lead (to either opening it up to 40% or closing it > > > > > to 98%, say) > > > > > 3) Let the community by itself determine organically which volunteers > > > > > from the community will plumb the 5% doubt. > > > > > 4) Design a bunch of devices that are based on a 95% assurance that > > > > > the principles of that model are correct, again weighing risk vs > > > > > benefit on the chance this is a mistake. > > > > > That's fair enough in abstract. But the question is still who pursues > > > > which avenue, and what subjective perception they have of the > > > > likelihood of a particular theory being correct. > > > > Yes, and that is done by self-selection. In the community of > > > scientists, the presumption is that open questions will be addressed > > > by someone eventually. And there is reward in the community for that > > > adventurism. The assessment of the risk vs benefit of the adventurism > > > is made individually. > > > Indeed. But it is then a sociological question, to ask which > > scientific questions are answered and which are not, and why. > > That's true. What I just stated is that the presumption is that > essentially all questions get answered eventually. Perhaps, but the question is "in what circumstances".
From: Ste on 1 Mar 2010 19:00 On 1 Mar, 16:28, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 28, 11:33 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 28 Feb, 17:20, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > > > On Feb 27, 8:42 am, Jerry <Cephalobus_alie...(a)comcast.net> wrote: > > > > > You should give Ste a specific book recommendation: > > > > > Spacetime Physics, by Taylor and Wheeler > > > > > The second edition can generally be picked up used for about $25. > > > > The first edition is frequently found on eBay with a "Buy it now" > > > > price of $5 to $10. > > > > [...] > > > > IMO that book stinks for explaining SR. It presents the math but > > > doesn't provide the underlying reason for the math. > > > Haha! And these pillocks wonder why I won't go out and spend a grand > > in money and 6 months of time, working through their extensive reading > > lists! > > Ah, so you're looking for a reference that is GUARANTEED by universal > acclamation to satisfy your learning needs? No, I'm simply justifying my failure to "work through this reading list"/"go back to education"/"learn some maths", when it my apprehension at the outset that embarking on these courses of action would not have resolved my questions, but would simply have wasted my time and money. 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.
From: Ste on 1 Mar 2010 19:10 On 1 Mar, 17:14, mpalenik <markpale...(a)gmail.com> wrote: > On Mar 1, 8:51 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > wrote: > > > > > > > >> > Stop making me laugh Peter. I have surely forgotten more about > > >> > evolution than you'll ever know, because you typify arrogance and > > >> > closed-mindedness. > > > >> I laughed when you first said what you thought evolution was about. > > > >> You said it explained the origon of life (amongst other things). > > > >> Evolution says nothing about that at all. > > > > Guffaw! "Evolution says nothing about the origin of life at all". I > > > wonder if Dirk van de Moortel would like that one for his "immortal > > > fumbles" page. > > > Interesting that you have forgotten more about evolution than I will ever > > know, because I can't actually recall Darwin's theory of evolution as saying > > anything at all about the origins of life. > > > What do you think it says about the origins of life, exactly? > > > (See. Like I said. You know even less about evolution than you do about SR.) > > Peter, here you go:http://en.wikipedia.org/wiki/Abiogenesis=/= > evolution > > "In the natural sciences, abiogenesis (pronounced /eɪËbaɪ.ɵËdÊÉnɨsɪs/, > ay-BYE-oh-JEN-É-siss) or biopoesis is the theory of how life on Earth > could have arisen from inanimate matter. It should not be confused > with evolution,. . ." Well I'm not sure I'd rely on Wikipedia for a contentious subject like this, but in any event we needn't talk specifically about how the basic DNA first developed. If we simply talk of the diversity of life on Earth, evolution is still unfalsifiable, because it makes no definite predictions about what you will see. Indeed it does not describe the characteristics of any common ancestor, and nor does it predict the evolution of any particular animal with any particular traits.
From: Inertial on 1 Mar 2010 19:15
"Ste" <ste_rose0(a)hotmail.com> wrote in message news:8580a441-d06e-47c4-87b5-7063c93a2b50(a)d27g2000yqf.googlegroups.com... > On 1 Mar, 16:28, PD <thedraperfam...(a)gmail.com> wrote: >> On Feb 28, 11:33 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> >> >> >> >> > On 28 Feb, 17:20, Bruce Richmond <bsr3...(a)my-deja.com> wrote: >> >> > > On Feb 27, 8:42 am, Jerry <Cephalobus_alie...(a)comcast.net> wrote: >> >> > > > You should give Ste a specific book recommendation: >> >> > > > Spacetime Physics, by Taylor and Wheeler >> >> > > > The second edition can generally be picked up used for about $25. >> > > > The first edition is frequently found on eBay with a "Buy it now" >> > > > price of $5 to $10. >> >> > > [...] >> >> > > IMO that book stinks for explaining SR. It presents the math but >> > > doesn't provide the underlying reason for the math. >> >> > Haha! And these pillocks wonder why I won't go out and spend a grand >> > in money and 6 months of time, working through their extensive reading >> > lists! >> >> Ah, so you're looking for a reference that is GUARANTEED by universal >> acclamation to satisfy your learning needs? > > No, I'm simply justifying my failure to "work through this reading > list"/"go back to education"/"learn some maths", There is no 'justification' for failure. > when it my > apprehension at the outset that embarking on these courses of action > would not have resolved my questions, but would simply have wasted my > time and money. Ahh .. so it is because you have problems with comprehension and understanding that you don't bother to read and learn, and then are surprised when you come her and have the same problems? > 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. It helps is you try to read and understand the subject BEFORE you discuss it (or in your case make unfounded criticism of it from ignorance). And helps if you learn the appropriate tools and the language required. Just don't go attributing YOUR failure to do so onto others. |