A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Ste on 8 Mar 2010 09:35 On 7 Mar, 02:51, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > news:651a713d-7ae4-4048-bafb-f1b3219ee4fc(a)v20g2000yqv.googlegroups.com... > > > > > > > On 6 Mar, 12:47, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > wrote: > >> > This should make perfect sense to you. If a clock is running 2% > >> > slower, then it is running 2% slower regardless of distance. But if, > >> > as a result of running 2% slower, it falls behind 6 minutes after > >> > running a certain amount of time, then it will fall behind 12 minutes > >> > after running for twice as long. > > >> Agreed. > > >> The question now is, if we agree that both clocks suffer time dilation > >> in this way, then when they return to the start point, how do they > >> each reconcile the fact that (after accounting for the effects of > >> acceleration) it ought to be the other clock which is slow, when in > >> fact one clock (the one that went furthest from the start point) will > >> be slower than the other? And a third clock, left at the start point, > >> will be running ahead of both? > > >> _________________________ > >> They know that the operations were not symmetric. Only one clock remained > >> in > >> the same inertial reference frame throughout. The other two clocks spent > >> different amounts of time in at least 3 different inertial reference > >> frames. > >> Everybody can see this is true, and so nobody expects that the clocks > >> will > >> remain synchronised. > > > Yes, but the important question here is whether they agree *after* the > > effects of acceleration are taken into account. I mean, if we said > > that each travelling clock slows by 2% when moving away from the start > > point at a certain speed, then by rights both travelling clocks should > > slow equally. Yes? > > As I understand your thought experiment, no. > > In SR, time dilation is a function of relative speed and the time for which > they are moving at the speed. It is not a function of accleration. > > A doesn't move. B moves at speed v for time t, and its clock will read x > behind A. C moves at speed v for time 2t, and its clock will read 2x behind > A. The question is this. We'll deal with only the outbound trip (in other words, the clocks are on the move, but time 't' has not yet elapsed, so there has been no further acceleration). I agree with your answer above, as it concerns A's frame. The question is, from the frame of B, what will the slowdown be on clock C, *after* having accounted for the increased distances between them (i.e. having accounted for the increased propagation delays). It seems to me that the natural answer is to say "4%".
From: Ste on 8 Mar 2010 09:42 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?
From: PD on 8 Mar 2010 14:12 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. PD
From: PD on 8 Mar 2010 14:14 On Mar 6, 5:58 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 5 Mar, 15:59, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Mar 5, 4:55 am, "Inertial" <relativ...(a)rest.com> wrote: > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > >news:057b5351-82a4-4487-8501-6308451c921a(a)x22g2000yqx.googlegroups.com.... > > > > > On 5 Mar, 01:31, "Inertial" <relativ...(a)rest.com> wrote: > > > >> "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > > >>news:8c0ae071-8d13-491b-92d0-cd2e2727af1a(a)u9g2000yqb.googlegroups.com... > > > > >> > On 4 Mar, 12:19, "Inertial" <relativ...(a)rest.com> wrote: > > > >> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > > >> >> > Not really, because if the total acceleration is small, then so is > > > >> >> > the > > > >> >> > speed. > > > > >> >> That is a nonsense argument. Acceleration can be small and speeds > > > >> >> very > > > >> >> large. > > > > >> > When I went to school, you could not have a large change of speed with > > > >> > only a small amount of total acceleration. > > > > >> Then you were badly taught. > > > > >> a) if you start at speed 0.8c and acceleration at 0.00001 m/s/s .. then > > > >> your > > > >> speed is still large. you claimed small acceleration means small speed > > > > >> b) if you start at speed 0.0 and acceleration at 0.00001 m/s/s .. then > > > >> your > > > >> speed after a million years will be quite fast. Yet the acceleration was > > > >> small and constant. > > > > >> You do realize that you cannot 'total' acceleration. and acceleration of > > > >> 1m/s/s followed by an acceleration of 1m/s/s is still an acceleration of > > > >> 1m/s/s > > > > > In any event, we've resolved the meaning of "total acceleration" - > > > > Mark suggests using the concept of "impulse" instead. > > > > You certainly are taking the long and painful route (for yourself and us) to > > > learn the basics of physics. > > > Ste: This is exactly what I was telling you earlier, that people will > > be less inclined to teach things on your terms, using your language > > and indulging your lack of skills, and will advise you that it is more > > efficient in the long run to teach after you've acquired some relevant > > skills and vocabulary. You didn't seem to think this was the case, and > > here you have others telling you the same thing. Reconsider? > > As I say Paul, the words "total acceleration" I think should have > given people some clue as to the meaning - and indeed the more > intelligent amongst us here did recognise the meaning, and suggested > an alternative word. That said, in this case I'm happy to use an > alternative formulation like "impulse", because I can see that it will > add further precision to my meanings in future. > > It's quite different from the disputes that arose over words like > "physical" and "material", where each side seems to battle childishly > over whose idiosyncratic understanding of the word will prevail, when > the time could be better used getting on with the substantive argument. Excellent. Then since you see the value of using a precisely defined term like "impulse", then I'm sure you'll have no problem using the precisely defined meanings of "physical" and "material" as they are understood in science.
From: PD on 8 Mar 2010 14:27
On Mar 6, 2:56 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > Just as some background, when I first studied EM waves in high school > the teacher told us that the speed of light was always c. If you were > standing on the ground it was c, and it was c for those in an airplane > flying by you. I asked how that could be? Why wasn't it c+v like it > would be for a sound wave or a bullet. His answer was "That's just > the way nature made things." When I didn't buy that answer he told me > "Thousands of scientists say it works that way. Who should I believe, > them or you." I'm sorry you had such a terrible HS science teacher. You would not encounter this response in a decent college class. > Whe I didn't accept that as an explaination I was told > that I could work the problems out my way and have them marked wrong, > or I could work them out his way and get them marked right. It was a > bitter pill to swollow but I just let it go at that. Never gave it > much thought again until I got on line and found this group. > > When I took the SATs I got a 730 in math and a combined score of > 1425. Just for fun I took the physics SAT and got a 700 on it. That > was over 40 years ago, but I don't think I have lost too many marbles > since then ;) > > Bruce |