A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: Simple Simon on 10 Mar 2010 11:52 PD wrote: > On Mar 9, 7:58 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: >> On Mar 9, 9:31 am, PD <thedraperfam...(a)gmail.com> wrote: >> >> >> >>> On Mar 8, 11:53 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: >> >>>> 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. 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? >> >>> No, there is no conflict. When you say that the tick rate does not >>> change, this is a LOCAL statement. What it means is that a process >>> measured locally with this clock will still have the same duration. >> >> 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. > > I don't know that length contraction IS an illusion. Length is > *defined* operationally by relying on simultaneity, and so the REAL > length according to that definition is of course frame-dependent, > because simultaneity is frame-dependent. ** For Sale ** One (1) slightly used Minkowsky (tm) Intervaler (with quantum sensors) This space-time meter (aka clock-ruler) will measure and generate intervals in space-time. In measuring intervals it will also produce the components of the interval for any inertial frame. In generating intervals it can act as a ruler if the intended interval is space-like and a clock if time-like. Say you're in Phoenix and your buddy is driving in from Tucson. You want to know when she'll be there and ask her to generate intervals, so you'll know when she'll be there. She takes our her Intervaler and decides to generate simultaneous (in her frame) events at your respective positions. You measure the interval with your Intervaler. In addition to telling you the velocity (of the inertial frame in which the events are simultaneous) and components of the interval in each frame (yours and hers), simply by changing the sign of the interval and dividing by c you can synchronize the interval with your legacy measuring tools (e.g. A clock, to arrive at an ETA). Fine print: Guaranty void where prohibited, e.g. near significant gravitation. > >> If it is an illusion >> the accumulated time on the two clocks should be the same when they >> are brought back together. The way Inertial described it, it came >> across as an illusion caused purely by clock sync. >> >> I hate discussing what is "real". In a sense length contraction is >> real because the pole will fit into the barn. > > Absolutely. If I have a clear understanding of what "simultaneous" > means in a given reference frame, and I close the barn doors > simultaneously with the pole between them, and there are no marks on > the doors where the pole hit either one of them, then I can't think of > any sensible meaning of "fit" that would hold these circumstances to > be true and yet the pole does not fit in the barn in this frame. And > since the pole fits, I cannot think of any sensible meaning of > "shorter" where the pole would fit in the barn and yet be not shorter > than the barn. > >> But with length >> contraction there is no accumulated length to inspect when the pole >> is brought to rest. > > This is true. The twin puzzle is a different animal that the barn-pole > paradox. In the twin puzzle, there is no symmetry in terms of inertial > motion. One twin is DEFINITELY not residing wholly in one inertial > reference frame, and that is a frame-independent observation. > >> I can see that the measured slowing of the clock is >> due to the rotation of the time coordinates when it changed frames, >> but that doesn't make it any less real. >> >>> For example, if the half-life of a muon that is slow in frame A and >>> is measured with a clock at rest in A is 2.2 us, then if you make >>> the same measurement of the half-life of a muon that is slow in >>> frame B and is measured with a clock at rest in B, clock B will >>> still show the half-life to be 2.2 us. In this sense, we say that >>> the clock tick rate has not changed, because measurements of local >>> phenomena are unchanged. >> >> Yes, but again you are measuring locally, more or less in the rest >> frame of the muon. We know that if we measure the half life of a fast >> moving muon it is longer, as if its personal clock was ticking >> slower. >> >>> However, this does NOT mean that the tick rate of clock B will agree >>> with the clock rate of all other clocks, nor that it will read the >>> durations of nonlocal processes to be the same. >> >>> Do you see the distinction? >> >> If we set up a light clock with a vertical bouncing beam, and have it >> send a flash back to the stay at home twin every time the beam hits >> the top, we can tell just how fast the clock is ticking. The signal >> will be doppler shifted, but the total count is what it is. None of >> the flashes drifted off and avoided detection. I am not claiming this >> slowing is due to motion wrt an ether. It is due to the finite speed >> of light and how we define/construct the coordinate systems. > > The last sentence is right, but how we define/construct the coordinate > systems is constrained by the structure of spacetime (and this in fact > produces the finite speed of light). That is, there is no way to > define/construct a coordinate system in our spacetime such that these > effects go away. (You are free to try.) > > PD > >> >> Bruce
From: PD on 10 Mar 2010 11:57 On Mar 9, 9:41 pm, Paul Stowe <theaether...(a)gmail.com> wrote: > On Mar 8, 8:05 pm, "Inertial" <relativ...(a)rest.com> wrote: > > > "Paul Stowe" <theaether...(a)gmail.com> wrote in message > > >news:1132a230-92d9-484a-b0c1-d3a97532cad9(a)z10g2000prh.googlegroups.com.... > > > >> >> SR explains it as having to be c due to the geometry of spacetime > > > >> > That's simply a silly idea... > > > >> That you think it is silly is your problem, not that of SR > > > > Something physical may be represented by a geometric description. > > > And our universe is represented by Minkowski geometry. > > Yes, you can descibe localized behavior with that format. BUT! to do > so you must depend on finite light speed and its physical > independence. Geometry neither predicts. explains, or has a basis for > that. > That's incorrect, Paul. The geometric structure of spacetime imposes both a finite speed of light AND makes it frame-independent. The geometric structure of spacetime *necessarily* divides pairs of events into three categories: spacelike-separated, timelike-separated, and nullcone-separated. This structure also immediately leads to the result that any wordline that could be traversed by something between timelike-separated events will, in any other inertial reference frame, still be between timelike-separated events. What this means explicitly is that this object can never span two spacelike-separated events. Thus, the universe of events is strictly divided into two completely separated causal domains. The boundary of these domains is the null cone. Since the null cone has a definite slope of space vs time, this imposes a causal speed limit. (This limit does not exist in Euclidean 3D+1D space -- it is a unique feature of the 4D space and its geometry.) Furthermore, while transformations between inertial frames will shift the slopes between pairs of timelike events (that is, the speed of an object traveling between the two events), the same transformation between pairs of events on the null cone do not change slope. What this means is that any object that can travel between two events on null cone will have the same speed regardless of inertial reference frame. So you see, the geometric structure DOES imply both a causal speed limit and the invariance of that causal speed limit with choice of inertial reference frame. It just so happens that light appears to be one of the candidate objects that can travel between nullcone- separated events. If you need to see how the structure does impose those limits formally, I could point you to a reference book or two that derives this unambiguously. At the time that Einstein proposed special relativity, he did not understand how such a geometric structure could produce those two conclusions as necessary consequences. And so he just posited the invariance of the speed of light as a postulate (or equivalently, demanded that Maxwell's equations obey the principle of relativity). It was only later that the geometric structure was uncovered and it was understood how the light postulate follows directly from this structure. PD
From: waldofj on 10 Mar 2010 12:36 On Mar 10, 10:11 am, "Dono." <sa...(a)comcast.net> wrote: > On Mar 10, 7:04 am, "Inertial" <relativ...(a)rest.com> wrote: > > > > > "Dono." <sa...(a)comcast.net> wrote in message > > >news:ae269f15-4a97-4e9b-9529-002823bd2ca6(a)n7g2000prc.googlegroups.com... > > > > On Mar 10, 6:54 am, "Inertial" <relativ...(a)rest.com> wrote: > > > >> > Because the "multiple aethers" would need to > > >> > have contradictory properties. > > > >> They probably would. Why can't multiple aethers have different > > >> properties? > > > > Because the properties in cause are CONTRADICTORY , imbecile. You keep > > > missing that. > > > The claim was that an aether for gravity would have different properties for > > one for EMR. There is no contradiction in that .. they can simply be > > different aethers with different properties. > > How can they? Their properties would not only be different but also > CONTRADICTORY. > > > If there is no contradictions > > (or not enough for aetherists to assert their way out of it) then the same > > aether can be used. > > If your grandmother had wheels she would have been a bus. The point is > that there IS contradiction. Fallacious thinking will not take you > very far. > > > It doesn't really matter which approach they take, but > > a determined aetherist can get out of the refutations put forward so far > > quite easily (as has happened in the past). > > You are a prime example. My understanding of the aether of LET is: it must have very great stiffness (i.e. very high modulus) so waves will propagate at the speed of light. It interacts with matter to cause a compression in the direction of motion. And yet, it does not cause any drag on matter moving through it so, for example, the earth can orbit the sun for 4.5 billion years in a nearly stable orbit. Now, if that last property isn't contradictory, I don't know what is. I think the point Inertial is trying to make is that the concept of an aether is already ad-hoc and self contradictory so it doesn't matter what else you pile on to it.
From: Dono. on 10 Mar 2010 13:11 On Mar 10, 9:36 am, waldofj <wald...(a)verizon.net> wrote: > On Mar 10, 10:11 am, "Dono." <sa...(a)comcast.net> wrote: > > > > > > > On Mar 10, 7:04 am, "Inertial" <relativ...(a)rest.com> wrote: > > > > "Dono." <sa...(a)comcast.net> wrote in message > > > >news:ae269f15-4a97-4e9b-9529-002823bd2ca6(a)n7g2000prc.googlegroups.com.... > > > > > On Mar 10, 6:54 am, "Inertial" <relativ...(a)rest.com> wrote: > > > > >> > Because the "multiple aethers" would need to > > > >> > have contradictory properties. > > > > >> They probably would. Why can't multiple aethers have different > > > >> properties? > > > > > Because the properties in cause are CONTRADICTORY , imbecile. You keep > > > > missing that. > > > > The claim was that an aether for gravity would have different properties for > > > one for EMR. There is no contradiction in that .. they can simply be > > > different aethers with different properties. > > > How can they? Their properties would not only be different but also > > CONTRADICTORY. > > > > If there is no contradictions > > > (or not enough for aetherists to assert their way out of it) then the same > > > aether can be used. > > > If your grandmother had wheels she would have been a bus. The point is > > that there IS contradiction. Fallacious thinking will not take you > > very far. > > > > It doesn't really matter which approach they take, but > > > a determined aetherist can get out of the refutations put forward so far > > > quite easily (as has happened in the past). > > > You are a prime example. > > My understanding of the aether of LET is: > it must have very great stiffness (i.e. very high modulus) so waves > will propagate at the speed of light. > It interacts with matter to cause a compression in the direction of > motion. > And yet, it does not cause any drag on matter moving through it so, > for example, the earth can orbit the sun for 4.5 billion years in a > nearly stable orbit. > > Now, if that last property isn't contradictory, I don't know what is. > > I think the point Inertial is trying to make is that the concept of an > aether is already ad-hoc and self contradictory so it doesn't matter > what else you pile on to it No, quite the contrary, Inertial doesn't admit that the concept of aether is self-contradictory. See his exchanges with Jerry. In the process, he keeps contradicting himself. It is a waste of time discussing with him. Both Jerry and I have given up on this idiot.
From: PD on 10 Mar 2010 13:47
On Mar 10, 12:11 pm, "Dono." <sa...(a)comcast.net> wrote: > On Mar 10, 9:36 am, waldofj <wald...(a)verizon.net> wrote: > > > > > On Mar 10, 10:11 am, "Dono." <sa...(a)comcast.net> wrote: > > > > On Mar 10, 7:04 am, "Inertial" <relativ...(a)rest.com> wrote: > > > > > "Dono." <sa...(a)comcast.net> wrote in message > > > > >news:ae269f15-4a97-4e9b-9529-002823bd2ca6(a)n7g2000prc.googlegroups.com... > > > > > > On Mar 10, 6:54 am, "Inertial" <relativ...(a)rest.com> wrote: > > > > > >> > Because the "multiple aethers" would need to > > > > >> > have contradictory properties. > > > > > >> They probably would. Why can't multiple aethers have different > > > > >> properties? > > > > > > Because the properties in cause are CONTRADICTORY , imbecile. You keep > > > > > missing that. > > > > > The claim was that an aether for gravity would have different properties for > > > > one for EMR. There is no contradiction in that .. they can simply be > > > > different aethers with different properties. > > > > How can they? Their properties would not only be different but also > > > CONTRADICTORY. > > > > > If there is no contradictions > > > > (or not enough for aetherists to assert their way out of it) then the same > > > > aether can be used. > > > > If your grandmother had wheels she would have been a bus. The point is > > > that there IS contradiction. Fallacious thinking will not take you > > > very far. > > > > > It doesn't really matter which approach they take, but > > > > a determined aetherist can get out of the refutations put forward so far > > > > quite easily (as has happened in the past). > > > > You are a prime example. > > > My understanding of the aether of LET is: > > it must have very great stiffness (i.e. very high modulus) so waves > > will propagate at the speed of light. > > It interacts with matter to cause a compression in the direction of > > motion. > > And yet, it does not cause any drag on matter moving through it so, > > for example, the earth can orbit the sun for 4.5 billion years in a > > nearly stable orbit. > > > Now, if that last property isn't contradictory, I don't know what is. > > > I think the point Inertial is trying to make is that the concept of an > > aether is already ad-hoc and self contradictory so it doesn't matter > > what else you pile on to it > > No, quite the contrary, Inertial doesn't admit that the concept of > aether is self-contradictory. See his exchanges with Jerry. In the > process, he keeps contradicting himself. It is a waste of time > discussing with him. Both Jerry and I have given up on this idiot. I don't think there's anything to admit. An aether that is supposed to have certain qualifiers to it -- such as solidity, where solidity means that it carries the expectation that it behaves like OTHER solids -- can certainly be said to be self- contradictory. This, in fact, is where a lot of aether types have been ruled out. Aethers that behave exactly like gases are ruled out. Aethers that behave exactly like solids have been ruled out. But what isn't necessarily ruled out is an aether that is UNLIKE any other substance previously known. This is the kind of aether that Inertial has been referring to, and in fact is similar to the kind of aether that Einstein mentioned is still permissible in relativity. The problem with the latter is that it is too slippery to pin down, and therefore impossible to experimentally test, and therefore scientifically useless. It is like invisible and very clever fairies that are the cause of momentum conservation but are perfectly adept at masking their presence and covering their tracks. There is no way to say that such fairies are self-contradictory, but on the other hand, there is no way to prove either that they exist or that they don't exist. PD |