A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: mpc755 on 11 Mar 2010 07:42 On Mar 10, 11:30 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > On Mar 10, 9:18 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > On Mar 10, 8:45 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > > > On Mar 10, 8:10 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > On Mar 10, 7:45 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > > > > > On Mar 10, 9:36 am, mpc755 <mpc...(a)gmail.com> wrote: > > > > > > > On Mar 10, 8:05 am, "Inertial" <relativ...(a)rest.com> wrote: > > > > > > > > "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote in message > > > > > > > >news:4b970c19$0$8039$afc38c87(a)news.optusnet.com.au... > > > > > > > > > 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. > > > > > > > > That's right. That's what Dono doesn't get. > > > > > > > > > Its only a small hop, skip and jump from saying that "it cannot be > > > > > > > > detected" to "it doesn't exist". > > > > > > > > Or at least 'it doesn't matter'. > > > > > > > > Once you go beyond just the aether frame, and relating frames directly to > > > > > > > it, LET becomes more of a hinderance than a help > > > > > > > > LET tells you (for instance) that even though objects at rest in frame A may > > > > > > > be more length compressed and time slowed than those in frame B (where A > > > > > > > moves faster in the aether frame than B) .. yet A will see objects at rest > > > > > > > in B as being more contracted and time dilated than its own. Which really > > > > > > > confuses those who use the simple 'motion in the aether shrinks and slows > > > > > > > things' idea of LET as a way to 'understand' into a spin. You end up with a > > > > > > > strange combination of real compression and apparent contraction, real > > > > > > > slowing and apparent time dilaton. Its not really helpful :):) > > > > > > > It is helpful in that it gets 'us' closer to understanding what occurs > > > > > > to objects as they move with respect to the aether. > > > > > > > The issue with LET is everything is relative. > > > > > > > For example, "the state of the [ether] is at every place determined by > > > > > > connections with the matter and the state of the ether in neighbouring > > > > > > places" - Albert Einstein. > > > > > > You like Einstein quotes about the ether so try this one: > > > > > >http://www-groups.dcs.st-and.ac.uk/~history/Extras/Einstein_ether.html > > > > > > "We may assume the existence of an ether; only we must give up > > > > > ascribing a definite state of motion to it" - Albert Einstein. > > > > > "If the existence of such floats for tracking the motion of the > > > > particles of a fluid were a fundamental impossibility in physics - if, > > > > in fact nothing else whatever were observable than the shape of the > > > > space occupied by the water as it varies in time, we should have no > > > > ground for the assumption that water consists of movable particles. > > > > But all the same we could characterise it as a medium." > > > > > "[extended physical objects to which the idea of motion cannot be > > > > applied] may not be thought of as consisting of particles which allow > > > > themselves to be separately tracked through time." > > > > > "The special theory of relativity forbids us to assume the ether to > > > > consist of particles observable through time, but the hypothesis of > > > > ether in itself is not in conflict with the special theory of > > > > relativity. Only we must be on our guard against ascribing a state of > > > > motion to the ether." > > > > > "But this ether may not be thought of as endowed with the quality > > > > characteristic of ponderable media, as consisting of parts which may > > > > be tracked through time. The idea of motion may not be applied to it." > > > > > Once you are willing to understand how Einstein defined motion, as > > > > particles which can be separately tracked through time, maybe you can > > > > advance from your statement. > > > > > p.s. You still haven't answered how it is the train is length > > > > contacted because it is moving relative to the aether and the > > > > embankment is more at rest with respect to the embankment but at the > > > > same time LET has everything being relative. The answer is both the > > > > Observer at M and the Observer at M' will determine the train to be > > > > length contracted and for the clocks on the train to be ticking slower > > > > than the clocks on the embankment. > > > > > > > This means the aether is more at rest with > > > > > > respect to the embankment than it is with respect to the train. The > > > > > > train is moving relative to the aether so it will be length contracted > > > > > > while the embankment will not. The ruler the Observer on the > > > > > > embankment uses to measure the length of the train is not length > > > > > > contracted. The ruler the Observer on the train uses to measure the > > > > > > length of the embankment is length contracted. The Observer on the > > > > > > embankment and the Observer on the train conclude the embankment is > > > > > > longer than the train. > > > > > > > The same holds true for the clocks on the train and on the embankment. > > > > > > Since the train is moving relative to the aether while the embankment > > > > > > is more at rest with respect to the aether there will be a greater > > > > > > pressure associated with the aether on the clock on the train causing > > > > > > it to tick slower. If the Observers on the embankment and on the train > > > > > > where able to 'see' each others clocks as the M and M' pass each other > > > > > > both the Observer on the train and the Observer on the embankment > > > > > > would conclude the clock on the train ticks slower than the clock on > > > > > > the embankment. > > > > You know for a while you were making progress. (I'm sure some here > > > are thinking the same about me ;) You managed to get away from each > > > frame having its own ether to having them share a single ether (for EM > > > waves anyway). Now if you could just get away from trying to attach > > > one of the frames to the ether... > > > > Did you ever get anywhere with that diagram I made to explain RoS to > > > you. Einstein presented the train experiment from the point of view > > > of the tracks, but he never said that the tracks were at rest WRT the > > > ether. > > > > - Hide quoted text - > > > > > > > - Show quoted text - > > > > > > According to both SR and LET there is no experiment that can reveal > > > > > which frame is at rest WRT the ether, so there is no way to know which > > > > > frame is more at rest WRT the ether. > > > > > The clock which ticks the fastest is most at rest with respect to the > > > > aether. > > > > But you have no way of knowing which clock is ticking faster. To > > > measure the tick rate of a moving clock requires more than one clock > > > at rest. And then you end up making assumptions to sychronize them.. > > > Those assumptions affect your measurements. > > > The two clocks are synchronized at some point in time. Then the clock > > at M and the clock at M' travel past one another. The Observer on the > > train and the Observer on the embankment have enough time to determine > > which clock is ticking faster. The clock which is ticking faster when > > M and M pass each other is the clock most at rest with respect to the > > aether.- Hide quoted text - > > > - Show quoted text - > > You need at least one more clock to measure a tic rate. Given clock > B, you compare the time on clock M to that on clock M' when they > pass. You cannot compare them a second time because M' is moving. So > you compare M' to B when they pass. With that comparison you can > decide whether the clock at M' has gained or lost time, but that > calculation assumes the clocks at M and B read the same. And > assumptions were required when those clocks were synchronized. Why can't you measure the clocks at M and M' a second time?
From: Ste on 11 Mar 2010 07:43 On 11 Mar, 01:51, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > No, perhaps you didn't understand. As I say, this is *not* the twins > paradox, because in the twins paradox only *one* twin leaves Earth. > > ________________________ > Its functionally the same. It is exactly the twins paradox, but with two > twins apparently doing exactly the same thing. > > Even if you cannot see that, the explanation on the Wikipedia page of the > Twins Paradox is trivially adapted for two twins. > > I assume that you do not understand the Wikipedia twins paradox page, or > else you would know the answers to your questions already. Which parts don't > you understand? Let's just go through it step by step Peter, as we have been doing. It's pointless spending 10 more postings arguing about how the Wikipedia page does or does not answer the question, or how it is or is not relevant. As I've just said in a post to Inertial, the only analogy between my scenario and the twins paradox is that, in my scenario, both twins leave Earth, and both return the same age as each other - hence no paradox, and hence bearing no resemblance at all to the twins paradox.
From: mpc755 on 11 Mar 2010 07:44 On Mar 10, 11:37 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > On Mar 10, 10:01 pm, mpc755 <mpc...(a)gmail.com> wrote: > > > > > On Mar 10, 8:52 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote: > > > > On Mar 10, 8:13 pm, "Peter Webb" > > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > > According to both SR and LET there is no experiment that can reveal > > > > which frame is at rest WRT the ether, so there is no way to know which > > > > frame is more at rest WRT the ether. > > > > > ______________________ > > > > Wrong. Only LET has this problem. There is no ether in SR, so the question > > > > of its velocity doesn't even arise. > > > > Einstein did not rule out the possibility of an ether, he said that it > > > made no difference if there was one, that it was superfluous. If you > > > claim my statement is wrong you are claiming there is an experiment > > > that can reveal the ether frame. > > > Another complete misquote of Einstein. > > >http://en.citizendium.org/wiki/Ether_%28physics%29 > > > 'In his 1905 paper Einstein refers to the ether only once: > > > The introduction of a "luminiferous aether" will prove to be > > superfluous inasmuch as the view here to be developed will not require > > an "absolutely stationary space" provided with special properties, nor > > assign a velocity vector to a point of the empty space in which > > electromagnetic processes take place.' > > > What part of 'inasmuch as the view here to be developed will not > > require "an absolutely stationary space"' do you not understand? > > > Just as you do not understand Einstein's definition of motion you do > > not understand what Einstein meant by a superfluous aether. > > > Einstein's definition of motion requires there to be particles which > > can be separately tracked through time. > > > Einstein's definition of a superfluous aether is one in which it is an > > absolutely stationary space. > > > The aether is displaced by matter. The aether is not at rest when > > displaced. The aether 'displaces back'. The pressure associated with > > the aether displaced by massive objects is gravity. A moving particle > > has an associated aether wave. > > Fine, go back to Neverland. > Fine, remain ignorant about what Einstein meant by a superfluous aether. How does this following quote fit with your misunderstanding of Einstein saying the aether makes no difference? "According to the general theory of relativity space without ether is unthinkable" - Albert Einstein
From: mpc755 on 11 Mar 2010 07:46 On Mar 11, 12:21 am, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message > > news:ca6a0dbf-23e8-42ff-b741-ae709e93dc66(a)z4g2000yqa.googlegroups.com... > On Mar 10, 10:39 pm, "Peter Webb" > > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message > > >news:1f04b278-4b2e-4602-9ce8-716f62cff45e(a)f8g2000yqn.googlegroups.com... > > On Mar 10, 8:13 pm, "Peter Webb" > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > > > According to both SR and LET there is no experiment that can reveal > > > which frame is at rest WRT the ether, so there is no way to know which > > > frame is more at rest WRT the ether. > > > > ______________________ > > > Wrong. Only LET has this problem. There is no ether in SR, so the > > > question > > > of its velocity doesn't even arise. > > > Einstein did not rule out the possibility of an ether, he said that it > > made no difference if there was one, that it was superfluous. > > > ___________________________ > > And indeed there is no ether in SR, so there is no problem with > > calculating > > its speed. A bit like saying that zoology has a problem because it doesn't > > say how fast Unicorns can run; it doesn't have a problem, as according to > > zoology Unicorn's don't even exist so they can't run. > > > If you > > claim my statement is wrong you are claiming there is an experiment > > that can reveal the ether frame. > > > __________________________ > > What part of "SR does not even include an ether" don't you understand? > > What part of "If there isn't one you can't measure it" do *you* not > understand? > > _____________________ > Do you think that zoology has a problem because it knows nothing about > Unicorns? > > The difference between LET and SR is that the ether exists in LET, but its > speed cannot be determined. SR doesn't even have an ether; they are > different situations. LET assumes that "Unicorns" exist but says some > properties cannot be determined; SR says they don't exist at all. And the aether exists in GR: "According to the general theory of relativity space without ether is unthinkable" - Albert Einstein And the aether exists in Einstein's 'first paper': http://www.worldscibooks.com/phy_etextbook/4454/4454_chap1.pdf So, yes there is an aether in SR.
From: Ste on 11 Mar 2010 07:48
On 11 Mar, 01:58, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > except for the fairly > > obvious explanation that it is the reference clock which is undergoing > > a "real" slowdown. > > Or, that you have no idea of what SR predicts, and have completely and > falsely assumed that observers see clocks jump ahead when turnaround occurs. I'm merely going off what "experts" here say happens. I didn't say there is a "leap ahead". Paul Draper (if I remember correctly) said there is a "leap ahead". Now perhaps I misunderstood, but that is what was said. |