A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Bruce Richmond on 9 Mar 2010 21:48 On Mar 9, 4:34 am, "Inertial" <relativ...(a)rest.com> wrote: > "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message > > news:51d25138-0494-4e1a-a46a-ee48ea24a394(a)g26g2000yqn.googlegroups.com... > > > > > > > On Mar 8, 1:58 am, "Inertial" <relativ...(a)rest.com> wrote: > >> "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message > > >>news:29fd9f7d-c9b4-41e6-b33a-585c3e0e7acf(a)q23g2000yqd.googlegroups.com.... > > >> > On Mar 7, 9:48 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> >> "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message > > >> >>news:1c6a2640-39f5-4ea4-9c85-127e71f4e6a2(a)33g2000yqj.googlegroups.com... > > >> >> > On Mar 7, 6:58 pm, "Inertial" <relativ...(a)rest.com> wrote: > >> >> >> "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote in > >> >> >> message > > >> >> >>news:4b943853$0$11336$afc38c87(a)news.optusnet.com.au... > > >> >> >> > "Inertial" <relativ...(a)rest.com> wrote in message > >> >> >> >news:4b942bcf$0$27789$c3e8da3(a)news.astraweb.com... > >> >> >> >> "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote in > >> >> >> >> message > >> >> >> >>news:4b93bf73$0$28464$afc38c87(a)news.optusnet.com.au... > > >> >> >> >>>>> 1) your statement: "For clarity, both effects are purely > >> >> >> >>>>> observational - SR presumes (ideal) clock mechanisms are > >> >> >> >>>>> completely > >> >> >> >>>>> unaffected by a clock's motion." -- I agree the physical > >> >> >> >>>>> mechanism > >> >> >> >>>>> of > >> >> >> >>>>> the clock is unaffected, but this is a really misleading > >> >> >> >>>>> statement, > >> >> >> >>>>> since the amount of proper time that the clock consumes is > >> >> >> >>>>> affected > >> >> >> >>>>> by > >> >> >> >>>>> its motion. Are you trying to say > > >> >> >> >>>> I was "trying to say" exactly what I did say. If you didn't > >> >> >> >>>> find > >> >> >> >>>> it > >> >> >> >>>> clear enough, try this: relative slow-downs/speed-ups observed > >> >> >> >>>> in > >> >> >> >>>> the > >> >> >> >>>> readings of SR's ideal clocks aren't due to changes in the > >> >> >> >>>> tick > >> >> >> >>>> mechanisms of those clocks. > > >> >> >> >>> I still don't find it clear, as it begs the question - it says > >> >> >> >>> what > >> >> >> >>> doesn't cause the change, not what does cause the change. > > >> >> >> >>> The standard SR answer is much more direct - the clocks slow > >> >> >> >>> down > >> >> >> >>> due > >> >> >> >>> to > >> >> >> >>> relativistic time dilatation from them being in different > >> >> >> >>> reference > >> >> >> >>> frames. > > >> >> >> >>> Is that standard position of SR also your position? Or is your > >> >> >> >>> somehow > >> >> >> >>> different? > > >> >> >> >> SR says that the difference in clock sync (clock settings) cause > >> >> >> >> the > >> >> >> >> measurement of length to be contracted and measurement of clock > >> >> >> >> ticking > >> >> >> >> rates to be dilated. > > >> >> >> > More or less. > > >> >> >> That's what it is :) > > >> >> >> > But I asked you about *your* position, not SR's position. > > >> >> >> My position is SR's position > > >> >> >> > Do you agree that that the clocks slow down due to relativistic > >> >> >> > time > >> >> >> > dilation, as predicted by SR, or not? > > >> >> >> They are measured as slower, just as a rod is measured as shorter. > >> >> >> This > >> >> >> is > >> >> >> due to the difference in simultaneity. They don't slow down > >> >> >> because a > >> >> >> moving observer is looking at them any more than a rod shrinks > >> >> >> because > >> >> >> a > >> >> >> relatively moving observer is looking at it. > > >> >> >> Here's a little example you might follow .. with time differences > >> >> >> exagerated > >> >> >> for clarity > > >> >> >> Here are six clocks, in tow rows (S and S'), all ticking at the > >> >> >> correct > >> >> >> rate, but set with different times... > > >> >> >> S' 10:30 11:00=A 11:30 <--v > >> >> >> S 11:30=C 11:00=B 10:30 -->v > > >> >> >> Clocks B sees the A is synchronized with it. > > >> >> >> Now .. the clocks are moving in opposite directions so after an > >> >> >> hour > >> >> >> we > >> >> >> have > > >> >> >> S' 11:30 12:00=A 12:30 > >> >> >> S 12:30=C 12:00=B 11:30 > > >> >> >> Clock A has moved away from clock B .. but another clock (C) in S > >> >> >> can > >> >> >> see > >> >> >> the time on it. Clock C sees that clock A is half an hour slow (A > >> >> >> shows > >> >> >> 12:00 when C shows 12:30). So according to the clocks in S, clock > >> >> >> A > >> >> >> is > >> >> >> ticking slower. We also note that clock B now sees a *different* > >> >> >> S' > >> >> >> clock > >> >> >> next to it as being fast (it shows 12:30 when B shows 12:00) > > >> >> >> If you look at the same scenario but from the point of view of the > >> >> >> other > >> >> >> row > >> >> >> of clocks, you get symmetric results. > > >> >> >> This is how clock synch affects measured ticking rates for moving > >> >> >> clocks > >> >> >> in > >> >> >> SR. Even though the clocks themselves do NOT change their > >> >> >> intrinsic > >> >> >> ticking > >> >> >> rates.- Hide quoted text - > > >> >> > Looks good, but let's take it one step further. The observer with > >> >> > clock A jumps to frame S" which is traveling in the same direction > >> >> > as > >> >> > S relative to S' but at twice the velocity. > > >> >> > S" 1:00 12:00=A 11:00 -->2v > >> >> > S' 11:30 12:00=A 12:30 <--v > >> >> > S 12:30=C 12:00=B 11:30 -->v > > >> >> > Clocks A and B continue to tick at there same intrinsic ticking rate > >> >> > and an hour later A has overtaken B. > > >> >> > S" 2:00 1:00=A > >> >> > 12:00 -->2v > >> >> > S' 12:30 1:00=A 1:30 > >> >> > <--v > >> >> > S 1:30=C 1:00=B > >> >> > 12:30 -->v > > >> >> > The above provides the same situation as the twins paradox. Clock A > >> >> > left clock B and returned. So why doesn't clock A show less time > >> >> > elapsed than B? (Note the clocks in S" are further out of sync than > >> >> > those in S due to the higher velocity.) > > >> >> The three clock situation cannot be so easily drawn .. bit like trying > >> >> to > >> >> drawing a three dimensional figure in 2d :) This sort of diagram only > >> >> really works for a single pair of clocks looking from a third frame in > >> >> which > >> >> they move with the same speed. Things are trickier when there is > >> >> frame > >> >> jumping going on :):)- Hide quoted text - > > >> >> - Show quoted text - > > >> > The question still remains, if there is no change in the tick rate of > >> > the clock, how can clock A have fewer ticks recorded when it is > >> > brought back to clock B? > > >> Look at the Lorentz transforms to see. Its all due to clock synch.- Hide > >> quoted text - > > >> - Show quoted text - > > > You are going to give yourself a head cold with all that arm waving. > > Do you REALLY need to to give you the SR explanation of the twins paradox? > > > You are saying the tick rate doesn't change, > > That's what SR says. I asked if that was what *you* were saying. Relativity says all kinds of things depending on who you listen to, including that moving clocks run slow. > But a moving observer will measure the tick rate as > slower. There you go frame jumping. We were discussing the stay at home twin, who is stationary, and the clock that changes its state of motion. > Just like the intrinsic length of a rod doesn't change because a > moving observer measures it. But we aren't talking about just observing it. The clock changed its state of motion. > > > yet SR says that the > > returning twin's clock will show less elapsed time. > > It will And I agree that it will. > > You don't see any > > conflict there? > > No .. do you? Yes. As I see it any admission that the clock has slowed is being surpressed to avoid possible connections to ether theory. That "Moving clocks run slow" used to be the standard line. As for what causes the different measurements depending on the frame, it's not just clock sync. Length contraction figures into it as well. I have been re-reading Bondi recently and he says the thing that makes time a dimension as opposed to just a data point is that when you do a rotation of coordinates the time gets mixed up with the space. He didn't mention it, but that also makes time dependent on position, which is what RoS is all about. I know I still have a long way to go but my goal here is to truely understand SR, not to just parrot explainations. LET helped me see that the math of SR is correct, but I also realize it has become a hiderence in understanding SR.
From: Bruce Richmond on 9 Mar 2010 21:58 On Mar 9, 9:03 pm, "Dono." <sa...(a)comcast.net> wrote: > On Mar 9, 5:58 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > > > > That is not what we were discussing. I agree that the clock continues > > to tick at a rate of one second per proper second in the rest frame of > > the clock. The question was whether the slowed tick rate measured in > > the frame of the stay at home twin is real, or an illusion due to the > > clock sync proceedure, as length contraction is. > > There is no "slowed tick rate in the frame of the stay at home twin". > There is less elapsed time for the travelling twi, period. I'm not into word games. If that's all you have to offer goodby. > This is the > result of the invariance of ds^2=(cdt)^2-(dx^2+dy^2+dz^2). > The twin with the larger (dx^2+dy^2+dz^2) experience less elapsed > time. The proof is obvious.
From: BURT on 9 Mar 2010 22:00 On Mar 8, 10:52 pm, "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. > > Any "conflict" is due to the imprecision of English, not a logical conflict > in expected outcomes. Light flow is a constant in empty space. Mitch Raemsch
From: Peter Webb on 9 Mar 2010 22:03 I know I still have a long way to go but my goal here is to truely understand SR, not to just parrot explainations. LET helped me see that the math of SR is correct, but I also realize it has become a hiderence in understanding SR. ________________________________ Good. There is one key insight which makes the jump from LET to SR a little easier (in my opinion). For all the talk of relative motion against the ether in LET, the equations work out exactly the same whatever you choose as the rest frame of the ether. So the actual rest frame of the ether cannot be detected within LET. Its only a small hop, skip and jump from saying that "it cannot be detected" to "it doesn't exist".
From: mpc755 on 9 Mar 2010 22:06
On Mar 9, 10:03 pm, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > I know I still have a long way to go but my goal here is to truely > understand SR, not to just parrot explainations. LET helped me see > that the math of SR is correct, but I also realize it has become a > hiderence in understanding SR. > > ________________________________ > Good. There is one key insight which makes the jump from LET to SR a little > easier (in my opinion). > > For all the talk of relative motion against the ether in LET, the equations > work out exactly the same whatever you choose as the rest frame of the > ether. So the actual rest frame of the ether cannot be detected within LET. > Its only a small hop, skip and jump from saying that "it cannot be detected" > to "it doesn't exist". It is a huge difference. Without aether there is no propagation of light. Without aether there is no gravity. The pressure associated with the aether displaced by massive objects is gravity. |