A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Peter Webb on 9 Mar 2010 09:07 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:28440e7b-bffc-4d93-a61b-90443ff83823(a)z11g2000yqz.googlegroups.com... On 8 Mar, 22:55, PD <thedraperfam...(a)gmail.com> wrote: > On Mar 6, 5:32 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > What confuses me is that, if the clocks run slow by 2% for all the > > time that they are moving, how does one reconcile this with the fact > > that, if one uses the frame of one of the moving clocks, say clock B, > > then it seems to be to be your argument that there is no slowdown at > > all for B, and it is the other clocks, A and C, that slow down (i.e. > > *disregarding* both acceleration and propagation delays). > > Be careful. The acceleration profiles are common between B and C, but > they are not common to A. So while there is no difference between B > and C due to the acceleration, you CANNOT say that the acceleration > has no effect whatsoever. In fact, it is the indisputable fact that B > and C accelerate and A does NOT accelerate that makes the situation > nonsymmetric for A. This is what makes the worldline for A straight, > and the worldline for B and C kinked. Yes, but we're supposed to have isolated the effect of acceleration, and disregarded it. And in any event, the more important question is the discrepancy between B and C. > Two places where I will try to intercept misconceptions. > 1. The first temptation is to say, well, if the kink is what's > responsible for the time dilation, then all the dilating must happen > during the acceleration. That is not the case. Note the time dilation > is different for B and C, even though they have the same kink (the > same acceleration profile). The fact that there IS a kink is what > makes the elapsed time less on B and C than it is on A (where there is > no kink), but how much less depends on the steepness and length of the > straight parts of the worldline on either side of the kink. As I say, I've stipulated that we are measuring on the outbound journey, before any of the clocks have turned back. So we've had one episode of acceleration and now B and C are travelling at the same speed away from the origin point, but in opposite directions. What amount of time dilation does C suffer relative to B? Nil? 2%? 4%? > 2. The second temptation is to say, well, in B's frame it does not > accelerate, and A does accelerate. This is not correct. I know. > Now, it IS fair to say that while the clock B is on its outward > journey at constant speed, it can look back at clock A and discern > that clock A is running slow relative to B. And the same goes on the > inbound journey. And so it's a fair question to say, how does it > happen then that by the time B lands back at A, it is BEHIND clock A? > And here is where things do get interesting in terms of what B sees in > terms of the clock reading on A in the turnaround. No, the question is between B and C, not B and A. I'm using B and C specifically in order to allow us to disregard any effects of acceleration. And we've already stipulated that, if B and C have the same acceleration profiles and travel the same distance before returning to A, then they will be in agreement with each other, but both will have slowed relative to A. The question is, while they are still on the outbound journey, what do B and C report about each other? Do they both agree with each other still? Or not? ___________________________________ What do you mean, "agree with each other"? You can only ask what are the results of observation. You can ask questions about what time clocks read, but not whether they with agree with each other, as this depends upon the frame of reference in which you observe them, and its not even defined anyway. If you are describing a symmetrical arrangement then both will see the same thing; relativity works the same way in a mirror image. To the extent that I understand your question, when they observe each others clocks when they are separating they will appear to run slowly, and then speed up when they come back together, to the exact amount such that they are back in sync. They will calculate that time is running slowly for the other clock when they are separating, because even accounting for the speed of light they will see time run more slowly for the other clock, and conversely when approaching.
From: PD on 9 Mar 2010 09:20 On Mar 9, 7:26 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Mar, 22:36, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Mar 8, 1:57 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 8 Mar, 19:12, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Mar 8, 8:42 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > On 4 Mar, 18:27, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > On Mar 4, 10:24 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > On 4 Mar, 15:54, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > > > On Mar 4, 1:03 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > > > > > This is what fundamentally sets apart things like creationism from > > > > > > > > > > > science. Whatever other hoops creationism manages to jump through, it > > > > > > > > > > > will never jump through the hoop of naturalism, and that is what > > > > > > > > > > > *fundamentally* sets it apart from science. > > > > > > > > > > > And also FUNDAMENTALLY distinguishes science from religion. Thanks. > > > > > > > > > > Agreed, but then religion in general never claimed to be science, > > > > > > > > > Agreed! And so science is not a religion in the same fashion. > > > > > > > > No, but neither did one religion ever claim to be the other. > > > > > > > > > > and > > > > > > > > > traditional religion is almost immediately identifiable by its > > > > > > > > > supernaturalism. Creationism is different in that it actually claims > > > > > > > > > to be scientific in some essential respects. > > > > > > > > > Ah, yes, but as has been demonstrated even to layfolk (Dover v > > > > > > > > Kitsmiller), this is an unsupportable claim. > > > > > > > > I agree. I'm glad you brought up that case. I just reviewed the > > > > > > > judgment quickly, and apparently the court agrees that the defining > > > > > > > essence of science is naturalism. > > > > > > > Gee, I didn't read that into the judgment at all. > > > > > > Then what did you read into it? > > > > > I didn't have to read into it. Take a look at page 64 of the 139-page > > > > decision: > > > > ======================================================= > > > > 4. Whether ID is Science > > > > > After a searching review of the record and applicable caselaw, we find > > > > that while ID arguments may be true, a proposition on which the Court > > > > takes no position, ID is not science. We find that ID fails on three > > > > different levels, any one of which is sufficient to preclude a > > > > determination that ID is science. They are: (1) ID violates the > > > > centuries-old ground rules of science by invoking and permitting > > > > supernatural causation; (2) the argument of irreducible complexity, > > > > central to ID, employs the same flawed and illogical contrived dualism > > > > that doomed creation science in the 1980's; and (3) IDs negative > > > > attacks on evolution have been refuted by the scientific community. As > > > > we will discuss in more detail below, it is additionally important to > > > > note that ID has failed to gain acceptance in the scientific > > > > community, it has not generated peer-reviewed publications, nor has it > > > > been the subject of testing and research. Expert testimony reveals > > > > that since the scientific revolution of the 16th and 17th centuries, > > > > science has been limited to the search for natural causes to explain > > > > natural phenomena. (9:19-22 (Haught); 5:25-29 (Pennock); 1:62 > > > > (Miller)). This revolution entailed the rejection of the appeal to > > > > authority, and by extension, revelation, in favor of empirical > > > > evidence. (5:28 (Pennock)). Since that time period, science has been a > > > > discipline in which testability, rather than any ecclesiastical > > > > authority or philosophical coherence, has been the measure of a > > > > scientific ideas worth. (9:21-22 (Haught); 1:63 (Miller)). In > > > > deliberately omitting theological or ultimate explanations for the > > > > existence or characteristics of the natural world, science does not > > > > consider issues of meaning and purpose in the world. (9:21 > > > > (Haught); 1:64, 87 (Miller)). While supernatural explanations may be > > > > important and have merit, they are not part of science. (3:103 > > > > (Miller); 9:19-20 (Haught)). This self-imposed convention of science, > > > > which limits inquiry to testable, natural explanations about the > > > > natural world, is referred to by philosophers as methodological > > > > naturalism and is sometimes known as the scientific method. > > > > ============================================ > > > > You'll note the emphasis on "testability, rather than any ... > > > > philosophical coherence" which provides a scientific idea's worth. > > > > Note also (emph. mine) "This self-imposed CONVENTION of science, which > > > > limits inquiry to TESTABLE, natural (NOT SUPERNATURAL) explanations > > > > about the natural world, is referred to by philosophers as > > > > 'methodological naturalism' and is sometimes known as the scientific > > > > method." > > > > > Creationism (and it was also judged that Intelligent Design is thinly > > > > disguised creationism) is simply not science, because it fails on the > > > > metric of testability, which is an indispensable component of the > > > > scientific method which in turn is indispensable to science. > > > > > It seems so plainly written to me. > > > > Then you are less accustomed to reading judgments than I am. It > > > mentions "natural" and "naturalism" 6 times in total, and mentions the > > > word "testable" only twice (and without necessarily relating > > > "testability" to "falsificationism"). > > > > The same is true of the whole judgment - it repeatedly refers > > > contrasts the supernaturalism of creationism (or specifically ID), > > > with the naturalism of science. I'm not saying one judgment of the > > > court is the final word on the matter, but it was your reference and > > > certainly the main emphasis is on the supernatural versus the natural, > > > not specifically the untestable versus testable (or any specific brand > > > of testability). > > > > Come on Paul, if this reference was supposed to support your > > > contention that falsificationism as opposed to naturalism defined > > > science, then it wasn't fit for purpose. > > > I certainly defer to you on the legal arcanery, as you should with me > > in the arcanery of physics. If you say that what is written in the > > judgment is tempered by how many times a word is used, and that if > > there is one sentence in a judgment that uses a word once, it means > > then it is not to be taken as true as statements that use a different > > word more than once, I certainly will have to take your word for it. > > No that's not what I said. > > What I did say is that, on account of the frequency with which the > judge (and the witnesses) connect science with naturalism (and as I > say, from a cursory glance it appeared to be a connection that ran > through the entire judgment), it does nothing for your position that > falsificationism is what defines science. According to this judgment, > a central pillar of science is naturalism. > > At the very least, we can agree that testability *and* naturalism > define science according to the judge. However there is no extensive > discussion of what "testable" means. Indeed, at times the judge and > the witnesses seem to treat "testable" as being almost synonymous with > naturalistic[1], and untestable as being a necessary entailment of the > supernaturalistic. Indeed the one and only occasion on which > "falsifiable" is mentioned (within a 140 page judgment), it is within > the context of saying that ID is necessarily not falsifiable *because* > is it not naturalistic. > > It is fair to say that, on the evidence that the court considered, the > arguments were strongly focussed towards distinguishing the natural > from the supernatural, not the falsifiable from the unfalsifiable. > > However, I'm not saying this judgment is the final word on the matter. > What I am saying is that it lent your position no support as against > mine. > > [1] Other sources have pointed out that virtually any statement about > the natural world is testable (at least notionally, if not practically > so). Also bear in mind that the court is not concerned with whether > science rests on belief. Only in whether ID is compatible with > science, which it clearly isn't. I see no point in belaboring this. You have interpreted the judgment to emphasize naturalism as being the defining feature of science, to the point where you even interpret testability to mean naturalism. You've had a number of scientists here vociferously emphasizing to you what testability means and how central that is to science, which you have dismissed. If you've made up your mind to the point where you find direct counterstatements to be not compelling, then I'll let you sit with your fixed opinion.
From: JT on 9 Mar 2010 09:24 On 9 mar, 07:52, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > - > > You are going to give yourself a head cold with all that arm waving. > You are saying the tick rate doesn't change, yet SR says that the > returning twin's clock will show less elapsed time. You don't see any > conflict there? > > ___________________________________ > > You are playing word games here, and you know it. His meaning is clear to me > and I believe to you as well. > > Just because English lacks words which refer specifically to relativistic > time dilation and the transformations which occur when you change reference > frames doesn't mean these aren't real; they can be easily, tersely and > unambiguously described mathematically as Einstein did in 1905. No there is no language conflict, the conflict is the claim that two systems with variant units of different magnitude the d/t=v=c and d'/ t'=v'=c represent same velocities and that both are c, when in reality c is variant. > Any "conflict" is due to the imprecision of English, not a logical conflict > in expected outcomes.
From: PD on 9 Mar 2010 09:26 On Mar 9, 7:49 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Mar, 22:55, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Mar 6, 5:32 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > What confuses me is that, if the clocks run slow by 2% for all the > > > time that they are moving, how does one reconcile this with the fact > > > that, if one uses the frame of one of the moving clocks, say clock B, > > > then it seems to be to be your argument that there is no slowdown at > > > all for B, and it is the other clocks, A and C, that slow down (i.e. > > > *disregarding* both acceleration and propagation delays). > > > Be careful. The acceleration profiles are common between B and C, but > > they are not common to A. So while there is no difference between B > > and C due to the acceleration, you CANNOT say that the acceleration > > has no effect whatsoever. In fact, it is the indisputable fact that B > > and C accelerate and A does NOT accelerate that makes the situation > > nonsymmetric for A. This is what makes the worldline for A straight, > > and the worldline for B and C kinked. > > Yes, but we're supposed to have isolated the effect of acceleration, > and disregarded it. No, we did not. We said that it cannot account for the DIFFERENCE between B and C, but this does not discount or remove acceleration from further consideration, particularly with regard to how clock A's rate is seen by B. > And in any event, the more important question is > the discrepancy between B and C. > > > Two places where I will try to intercept misconceptions. > > 1. The first temptation is to say, well, if the kink is what's > > responsible for the time dilation, then all the dilating must happen > > during the acceleration. That is not the case. Note the time dilation > > is different for B and C, even though they have the same kink (the > > same acceleration profile). The fact that there IS a kink is what > > makes the elapsed time less on B and C than it is on A (where there is > > no kink), but how much less depends on the steepness and length of the > > straight parts of the worldline on either side of the kink. > > As I say, I've stipulated that we are measuring on the outbound > journey, before any of the clocks have turned back. So we've had one > episode of acceleration and now B and C are travelling at the same > speed away from the origin point, but in opposite directions. What > amount of time dilation does C suffer relative to B? Nil? 2%? 4%? It's not that simple, and to get a number, you need to use the math. Sorry, but that's the facts. The 2% is the Lorentz dilation factor, and that is given by a function 1/sqrt(1-v^2/c^2), and you can see that doubling the speed will not double the Lorentz dilation factor. Furthermore, the speed of C relative to B is not twice the velocity of B with respect to A, because the relation for combining velocities is (v1+v2)/(1+v1*v2/c^2). To find out what the Lorentz dilation factor is for C relative to B, then you simply need to put in the numbers and crank. > > > 2. The second temptation is to say, well, in B's frame it does not > > accelerate, and A does accelerate. This is not correct. > > I know. > > > Now, it IS fair to say that while the clock B is on its outward > > journey at constant speed, it can look back at clock A and discern > > that clock A is running slow relative to B. And the same goes on the > > inbound journey. And so it's a fair question to say, how does it > > happen then that by the time B lands back at A, it is BEHIND clock A? > > And here is where things do get interesting in terms of what B sees in > > terms of the clock reading on A in the turnaround. > > No, the question is between B and C, not B and A. I'm using B and C > specifically in order to allow us to disregard any effects of > acceleration. > > And we've already stipulated that, if B and C have the same > acceleration profiles and travel the same distance before returning to > A, then they will be in agreement with each other, but both will have > slowed relative to A. The question is, while they are still on the > outbound journey, what do B and C report about each other? Do they > both agree with each other still? Or not?
From: Sue... on 9 Mar 2010 09:28
On Mar 9, 9:07 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:28440e7b-bffc-4d93-a61b-90443ff83823(a)z11g2000yqz.googlegroups.com... > On 8 Mar, 22:55, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Mar 6, 5:32 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > What confuses me is that, if the clocks run slow by 2% for all the > > > time that they are moving, how does one reconcile this with the fact > > > that, if one uses the frame of one of the moving clocks, say clock B, > > > then it seems to be to be your argument that there is no slowdown at > > > all for B, and it is the other clocks, A and C, that slow down (i.e. > > > *disregarding* both acceleration and propagation delays). > > > Be careful. The acceleration profiles are common between B and C, but > > they are not common to A. So while there is no difference between B > > and C due to the acceleration, you CANNOT say that the acceleration > > has no effect whatsoever. In fact, it is the indisputable fact that B > > and C accelerate and A does NOT accelerate that makes the situation > > nonsymmetric for A. This is what makes the worldline for A straight, > > and the worldline for B and C kinked. > > Yes, but we're supposed to have isolated the effect of acceleration, > and disregarded it. And in any event, the more important question is > the discrepancy between B and C. > > > Two places where I will try to intercept misconceptions. > > 1. The first temptation is to say, well, if the kink is what's > > responsible for the time dilation, then all the dilating must happen > > during the acceleration. That is not the case. Note the time dilation > > is different for B and C, even though they have the same kink (the > > same acceleration profile). The fact that there IS a kink is what > > makes the elapsed time less on B and C than it is on A (where there is > > no kink), but how much less depends on the steepness and length of the > > straight parts of the worldline on either side of the kink. > > As I say, I've stipulated that we are measuring on the outbound > journey, before any of the clocks have turned back. What makes your *stipulations* any more physical than those of the theory's author? <<After further consideration you cast a somewhat disdainful glance at meand rightly soand you declare: I maintain my previous definition nevertheless, because in reality it assumes absolutely nothing about light. There is only one demand to be made of the definition of simultaneity, namely, that in every real case it must supply us with an empirical decision as to whether or not the conception that has to be defined is fulfilled. That my definition satisfies this demand is indisputable. That light requires the same time to traverse the path A > M as for the path B > M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which I can make of my own freewill in order to arrive at a definition of simultaneity. >> http://www.bartleby.com/173/8.html <<...one of Einstein's two main reasons for abandoning special relativity as a suitable framework for physics was the fact that, no less than Newtonian mechanics, special relativity is based on the unjustified and epistemologically problematical assumption of a preferred class of reference frames, precisely the issue raised by the twins paradox. Today the "special theory" exists only, aside from its historical importance, as a convenient set of widely applicable formulas for important limiting cases of the general theory, but the epistemological foundation of those formulas must be sought in the context of the general theory. >> http://www.mathpages.com/rr/s4-07/4-07.htm Classical Electromagnetism: An intermediate level course Richard Fitzpatrick Associate Professor of Physics The University of Texas at Austin http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html Sue... > So we've had one [...] |