Known physics defeated by simple puzzle?
in [Physics]
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From: Inertial on 7 Apr 2010 20:28 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:afbe8d7d-8ea1-4ad4-9cc5-3759a6a248d8(a)i37g2000yqn.googlegroups.com... > On 7 Apr, 15:49, "Inertial" <relativ...(a)rest.com> wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> news:cf5cd01b-0da3-41b0-88b5-69b2e678a011(a)z7g2000yqb.googlegroups.com... >> >> > On 7 Apr, 05:08, "Inertial" <relativ...(a)rest.com> wrote: >> >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >> >> > Again, hidden in the meaning here is 100km/h >> >> >> > *relative to what*. An object cannot travel at *both* 100km/h >> >> >> > *and* >> >> >> > 50 >> >> >> > km/hr *relative to me*. >> >> >> >> I didn't say it could. But we are talking about things being >> >> >> real.. >> >> >> you >> >> >> claim that all observers have to agree about the value for it to be >> >> >> real. >> >> >> > Yes, I do say that! >> >> >> So velocity is not real, momentum is not real, kinetic energy is not >> >> real, >> >> length is not real, time is not real etc etc. >> >> >> Is that REALLY what you want to be saying? >> >> > But I'm not saying that, am I? >> >> By implication, yes, you are >> >> > You're the one putting these words in >> > my mouth. >> >> No .. I am applying your definition. >> >> If that is NOT what you want to be saying, then you should change yoru >> definition > > No Inertial, you're not applying my definition, Yes .. I am > because you don't even > understand my definition. I do > What you've done is seized on the ambiguity, Then stop using ambiguous terms > interpreted the definition of the words in entirely your own way, Nope > and > then proceeded to parody that definition relentlessly throughout your > posts, as though I had conceded that your understanding of the > definition was consistent with the definition that I hold. I am using your definition. If you can now see that it produces silly results, change it. > The real problem, as it were, is that you're not interested in getting > to grips with the definition, I already have > or trying to grasp the heuristic meaning > without haggling all day about the precise definitions. Your flawed definition is not my problem. > You're really > interested in showing that my definitions and indeed my thinking is > absurd (whether or not it is), It is. You need to fix that before you can make progress. > and of course it's fatal for any > productive communication. Then stop using flawed definitions. > And also, it's worth pointing out that if you think I'm regularly > adopting a posture of "scoring points", So it appears > it's only because that is > precisely the posture that many people here are adopting against me, > and I'm naturally being forced to attack their arrogance and break > down their perceptions that either I am ignorant, But you are. > or that they are > faultless communicators, because only when that perception of > inequality has gone (if indeed it can be banished) will people become > more interested in *explaining* the theory (and quite possibly realise > that their own explanations are inadequate) rather than merely > affirming the truth of the theory with no explanation. We cannot explain when your thinking and usage of terms is so confused. >> >> >> As different observers disagree about what the velocity of any >> >> >> object >> >> >> is, >> >> >> that means its velocity isn't real. >> >> >> > No. As I just explained, "an object cannot travel at both 100km/h >> >> > and >> >> > 50 km/hr relative to me." >> >> >> Velocity is measured by each observer relative to his own frame of >> >> reference. That's the whole point. >> >> > No, the whole point is that the "frame dependence" of the measurement >> > is because, in reality, we're actually measuring the speeds relative >> > to two different objects. >> >> Derr .. what do you think frame dependence means. > > But you say that "length" is also "frame dependent", Yes > but as I've > painstakingly tried to explain, with the ladder and barn, there are no > other relevant objects to make reference to. Of course there are.. just like there is with velocity > Indeed, we would not say "the ladder and barn have a closing speed of . > 9c in the barn frame, and .8c in the ladder frame", Of course not .. why would we say something so silly? > because we're > talking about the *same objects* and quantifying the *same* > relationship. The same ought to be true of this length contraction > issue It is .. the ladder is shorter in the barn frame, and the barn is shorter in the ladder frame. It is all symmetric > - it should not be possible to say "the ladder is smaller than > the barn in the barn frame, and the barn is smaller than the ladder in > the ladder frame", Of course it is .. that is symmetric > because you're describing the same relationship Relationships between frame dependent values > (whether one object is bigger or smaller than the other), and yet each > are reporting logically contradictory statements. If you and I are relatively moving. I would say that I am at rest and you are moving faster than me. You would say YOU are at rest, and I am moving faster than you. That is not a contradiction. >> > It is however contradictory to say that "the ladder fits in the barn" >> > and "the ladder doesn't fit in the barn", provided that we're talking >> > about the same ladder and barn in both cases (which we are). >> >> Se.. there's your stumbling block. You think that 'fits in the barn' is >> frame independent. It is not > > Then *why* is it not frame independent, in the same way that closing > speed is, for example. That isn't either > There's no point saying "because of SR" - that > is no explanation at all. Because that is how the geometry of the universe works. Because you are more familiar with the degererate cases at low velocities wher eit appears length and time are unaffected, you think that must be how the universe works regardless of speeds .. its an error of scale. >> > I've explained >> > how the language used to describe relative velocity is not self- >> > contradictory in the way that it is contradictory to say that "the >> > ladder fits and doesn't fit". I've also explained that, with relative >> > velocity, all observers agree on all measurements. >> >> No .. you've shown how closing speeds are (ignoring SR for now) the same >> for >> all observers. But velocities are not. Velocity and closing speed are >> different measurement. > > Well it's besides the point. You seem to brush aside arguments that you lose like that. > If all observers agree about closing > speeds with reference to every object, They don't > then they must all agree about > velocity No .. not even if you ignore SR. They do not all agree about velocity. > - any remaining numerical difference in velocity is a > mathematical artefact, and not a reflection of any "real" difference. Nonsense. Again .. back to the object that has a velocity of 100km/hr for one observer and 50km/hr for another. That difference isn't a mathematical artefact. It is a real difference in velocity of the object in those frames >> > I've also pointed out that, if >> > these clocks are moving, then trying to ascertain the reality of >> > whether the clocks are synchronised or not becomes even more >> > confounded. >> >> For you, yes. That is not a surprise > > No, I didn't mean "for me". But apparently it is. > It was just hyperbole, to show that the > calculations become more complex, not to show that it was beyond my > comprehension. And incidentally, I notice the point scoring continues > without relent, instead of a simple acknowledgement of the valid > point. You have not made one >> > Indeed, if we hold axiomatically that 'c' is always >> > constant, then it follows that either time must have suddenly slowed >> > down locally, or the distances between the local and distant clock >> > must have suddenly "contracted". >> >> There's not 'suddenly' invovled. > > I meant "upon the slowing of the clocks". Nonsense > Again, why do we have to > haggle and contradict all the time about trivial ambiguities? Do you > think you're actually being smart, Intelligent > actually telling me anything I > don't know, when you pick up on every slight lack of precision? Yes .. because what you are saying is nonsense. Simultaneously slowing down a pair of separated clocks does not have any effect on space or time. Only on the clock readings. >> And both measured distances and durations >> are affected. > > Indeed, so is this a concession? Affected by SR.. not by just slowing a clock (as it appears you are talking about) >> > The fact that I can discuss all these examples, and not get a response >> > along the lines of "Yes, I know exactly what you mean Steven, and >> > you're quite right about how you describe these effects/scenarios. >> >> But you aren't > > But by the same token, even if you don't accept my statements, nor do > you rebut them logically. Yes .. I have > Even now, you simply say "but you aren't > [right]", and there is no follow-on, no attempt to reason about the > issues in question. There are far too many thing that you are wrong about. And these posts are WAY too long already But if you wish to ask why it is you are wrong, feel free. Though you probably won't understand the math involved to show your error. >> > The property of "fitting" is a relationship between the >> > ladder and the barn. >> >> No .. it is a property of the ladder, barn, and observer >> >> > We are talking about the same ladder and barn in >> > all cases, >> >> But different observers > > But we're not talking about the bloody observer! Yes .. we are. > We're talking about, > firstly, the barn, and secondly, the ladder. And an observer in the ladder frame who is determining if the pole fits within. > We're not talking about > the relationship between the barn, ladder, and any particular > observer. We're talking about only the barn and ladder. In which frame of reference .. because the relationships are frame dependent. The observer is the way of specifying the frame of reference > To go back to the audio analogy, oh gawd > there should be no reference made > about the "received frequency", which can be affected by the vagaries > of the audio interaction. I want to know something about the > properties of the *source*. but you are asking about fitting between the barn doors when they are simultaneously closed. That is a frame dependent question > Or are you saying that the barn and ladder don't have a quality of > "fitting" unless they are being observed? Whether or not they fit depends on the the frame of reference. Just as whether an object is a t rest of not depends on the frame of reference >> > in a way that we are *not* when we discuss relative >> > velocity between observer and object, where there is an implicit >> > change in the observer being referred to in the measurement. >> >> As there is when talking about whether different observers measure the >> pole >> as fitting. > > But you still don't get it. I *do8 get it. We are trying here to help *you* get it. it is an up=-hill battle > "Fitting" is not a relationship between > obsever and ladder. No .. it is an observer (frame) dependent measurement of the relationship between barn and ladder > It is a relationship between ladder and barn. No .. it is an observer (frame) dependent measurement of the relationship between barn and ladder > Why > on Earth would the observer's presence and circumstances affect the > fitting of these two objects, that are totally independent of the > observer? Because .. it is an observer (frame) dependent measurement of the relationship between barn and ladder >> > We are talking about the object in question >> > having a speed of 50kmh relative to one object, and a speed of 100kmh >> > relative to a *different* object than the first. >> >> But it is the ONE object having the two velocities at the same time .. >> depending on who is measuring them > > No, the "one object" doesn't have "two velocities". Yes .. it does. It has an infinite number of velocities. In particular we had the example of a single object with velocity of 50km/hr and 100kim/hr. You're missing some very basic concepts here. > The one object has > one velocity with respect to every other object, But not the same velocity for each other object. > because each object > can have a different relationship with every other object. That's right .. and so you get one object having different velocities at the same time in difference frames of reference. > But that answer's not available here, because we're talking about only > two objects (ladder and barn), and one relationship (fitting). We are talking about a frame dependent measurement (like velocity is). If you do not specify the frame, you cannot say whether 'fitting between the barn doors when closed simultaneously' (ie a particular length measurement) is correct or not. >> > There are, >> > essentially, three objects being referred to here. >> >> > If we go back to the coin-on-plane scenario, the three objects are: >> > firstly, the coin; secondly, the plane/the passenger; and thirdly, the >> > Earth/the man on the ground. And for any two of those three objects, >> > there is an invariant velocity that all observers agree on. >> >> If we ignore SR, yes. Because in that case lengths are NOT frame >> dependent >> and time is absolute and simultaneity is absolute. >> >> That does not apply in SR (and in the real world which SR models better >> than >> classical physics) > > For crying out loud Inertial. SR is the very thing in question. I know that. Gees > By > saying that "this does not apply in SR", you are *presupposing the > truth* of your interpretation of the theory in question, No. What the theory says .. not my particular interpretation of it. > but you're > not explaining that interpretation. There is no room for differences of interpretation. The theory is very clear in what it says. >> > because the two objects to which the property of >> > "fitting" applies, namely the ladder and barn, >> >> You missed out on the observer. Its a three-object thing > > Ahh. So no qualities of the external world exist unless there is an > "observer"? I said nothing of the sort. Gees. You do have major problems in comprehension. However, I *do* say that the particular values of many qualities depend on which observer (ie which frame of reference is used) is measuring them. > In other words, the ladder cannot "fit" or "not fit" into > the barn, unless there is a third object watching them? I said nothing of the sort. Gees. You do have major problems in comprehension. You need to qualify the 'fit' with a frame of reference. Just as saying 'the object is travelling at 100km/hr' needs to by relative to some frame of refrence. > Are you sure you aren't subtly falling back into talking about "the > received audio frequency", when I want to talk about "the source > frequency"? 'fitting at a given time' is a frame dependent concept. The problem is like someone talking about 'received frequency' but incorrectly calling it 'source frequency' .. the problem is your labeling of 'fitting' as an absolute. It isn't. >> > but that's not materialism - it's going >> > back to saying that the tree falling in the forest only makes a sound >> > if an observer heard it. >> >> Nonsense. You are the one who above pointed out the with the object >> moving >> at 50km/hr and 100km/hr you have to consider the objects you are >> measureing >> relative to (ie the frame of reference). > > Yes. But you only have to reference two objects to describe a closing > speed. No .. three. You need a frame of reference. > You don't say "objects A and B were closing at 100kmh according > to Jack" Yes .. you do > and "objects A and B were closing at 50kmh according to > Jill", Yes .. you do > because that would be contradictory (assuming that the > definition of "kmh" is itself common between Jack and Jill). No .. it isn't. Because closing speed is also frame dependent. > You could say "objects A and B were closing at 100kmh according to > Jack" and "objects A and B were closing at 100kmh according to Jill", > but since the observer has no bearing on the measurement, why > reference him at all? Because that is wrong >> Please.. try to be consistent. > > I am being very consistent. No .. you aren't. Perhaps you cannot understand your inconsistency. >> > My arguments are perfectly reasonable. >> >> But wrong > > I wonder, have you seen the Family Guy episode where you have the mule > having a political argument in the pub just shouting "no, no, no" and > eventually it just starts screaming and kicks over the table or > whatever. No >> > And my >> > question is this: "does the ladder fit with both doors shut, or not?". >> >> You cannot answer unless you give a frame of reference . .as implicit in >> that is 'shut simultaneously'. and 'simultaneously' is a frame dependent >> notion. > > Not if we use "steven-simultaneity" not even then > - that allows a frame-independent > description of simultaneity, It doesn't, unless you rule out SR > and is precisely the definition that I > wanted to use for "simultaneous". It doesn't, unless you rule out SR >> > It cannot fit and not fit at the same time. >> >> And an object cannot travel at 50km/hr and 100km/hr at the same time. >> >> Unless it is relative to different frames of reference > > Indeed, YES !! > but what conclusion are we to draw here? That fitting (which is just a length measurement) is similar .. it is frame dependent. > The bare bones of my > point is that saying "the red car moves at 50kmh relative to the > house, and the green car moves at 100kmh relative to the house". That > doesn't mean "the house is moving at *both* 100kmh and 50kmh" Yes it is > - it > means the house is moving at different speeds relative to *different* > cars, Same thing > and the truth of that is so bare-bollocks obvious that I don't > even know why we're talking about it. Because it is one of your many stumbling blocks. Did you read what you wrote above (paraphrasing): that doesn't mean it is moving at difference velocities, it means they are moving at different velocities. A velocity is (by definition) relative to a frame of reference. There is no absolute velocity. > The problem for you is that it is *not* obvious why the *same* two > objects, the ladder and barn, would describe their own relationship > differently to each other, unless there is an illusion in play. There is no illusion. You just cannot seem to get it into your head that you can get different values for the same 'thing' from different frames of reference. THAT is your major problem here. You just can't accept that simultaneity is frame dependent, and length is frame dependent and time durations are frame dependent. You are stuck in a known-to-be-incorrect Newtonian/Gallilean view of the world, and try to shoehorn SR into that. It won't work. If you continue to insist that the world MUST work the way you think it should .. ( that simultaneity is absolute, and if something has a given length, then every observer must agree with that, and the if an hour elapses for one observer between to events, then it must be an hour for all observers etc) .. then you are never going to be able to accept SR and the way the world really does work. [snip rest.. there's no point in continuing ] > Also, as a final point, are you sure your figures are correct about > your chosen frame? A 1kg mass moving at velocity 6, will produce a KE > of 18 according to your equation - producing a difference of -10. Sorry .. yes.. i forgot the multiply by 1/2 (blush). Sorry .. my mistake. Please divide all the energy values I quoted by tow. That does not change the conclusion that difference in energy is frame dependent.
From: PD on 7 Apr 2010 20:39 On Apr 7, 6:35 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 7 Apr, 20:31, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Apr 7, 1:47 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > Miguel, you seem to think that I don't properly understand the ladder > > > and barn paradox. Let me correct you, I understand it completely. I > > > can even tell you what would happen, working within the same tenets, > > > if with careful timing you sent in *two* ladders in *opposite* > > > directions, and shut the doors simultaneously (according to the barn > > > frame) so as to contain both ladders for an instant with an > > > interference fit. > > > > What I'm questioning is whether this "paradox" actually reflects > > > reality at all. It is easy to conceive of mathematical models that are > > > internally consistent, ostensibly fit the existing evidence, but have > > > no basis in reality - mainstream economics abounds with such models > > > (and is widely regarded as being empirically discredited, and the > > > maths regarded as obfuscatory). > > > It is virtually unheard of in physics, despite your experience with > > economics, that a model is internally consistent, fits the existing > > evidence, and *continues to make accurate predictions of new > > measurements*, and still has no basis in reality. > > Well that adds another layer of qualification to what I said. But > certainly, almost every discredited scientific model started out life > internally consistent, ostensibly fitting the existing evidence, > continuing to make further valid predictions, and then ultimately > being found to be flawed as a physical model. It was found flawed by disagreeing with experimental results at some point. That's how that determination is made. > > > In physics, a model > > that is internally consistent and has a good fit to all known and > > ongoing measurements is a GOOD model by operational assumption, until > > such time as it begins to fail having a good fit to measurements. > > I think it's a bit more complex than that, but I don't want to rehash > old contentions between us. > > > I notice your statement that there are many economic models that fit > > the existing evidence and yet are empirically discredited. You can > > imagine my confusion about that. > > Indeed, I should have been more clear. What I meant is that mainstream > (i.e. neoclassical) economics abounds with mathematical models, which > have generally fitted the data to varying degrees at one time or > another. But more strongly in recent times, economists and other > miscellaneous commentators are pointing out that the very axioms of > neoclassical economics is increasingly contradicted by the empirical > evidence, and that most of these economic models are extremely fragile > and ad hoc (if indeed they do fit any evidence at all), and the > economic (and indeed social and legal) policies derived from them are > also absurd and contradicted by the growing body of evidence. > > But obviously economics, like physics, does not simply discard a model > at once when it fails to fit with the evidence. > > > > > > That leads on to my real question here. I'm not interested in being > > > told *what* SR predicts - which is what you've done here again for the > > > umpteenth time. I'm interesting in an explanation of *why* these > > > predictions would be what they are. > > > This will ultimately boil down to a couple of statements: > > 1. Maxwell's laws of electromagnetism, as well as other physical laws > > like them, work to accurately model reality, as evidenced by their fit > > to experimental data. > > 2. Physical laws all have the same form in any inertial reference > > frame. > > > Now, getting from these two statements to the conclusions of the > > ladder and pole situation -- or for that matter, situations that have > > been directly and unambiguously tested -- requires pages and pages of > > exposition if done in words. It will take much less if done with > > algebra. > > I'm sure they say that in economics, too. It's been pointed out before > that many modern economists are totally *unable* to use words at all, > in order to reason in the way that their predecessors in the subject > area did. Many economists compete on the elegance and rigour of their > mathematical models, rather than the correspondence of those models to > reality. > > Anyway, if the maths is to be understood at all, it simply means that > the words will be written down somewhere else, or conveyed by word of > mouth - it doesn't eliminate the need for qualitative explanations > that only words can properly communicate. I agree. Most books use a mixture for that reason, using math where it is reasonable that the reader is sufficiently comfortable with that shorthand to be able to mentally translate it into equivalent text in the mind. However, to do so without any math at all takes quite a bit more words.
From: Y.Porat on 7 Apr 2010 21:13 On Apr 7, 9:31 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 7, 1:47 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 7 Apr, 14:03, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > > > > On 7 abr, 03:01, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 7 Apr, 05:08, "Inertial" <relativ...(a)rest.com> wrote: > > > > > > yes .. just as we would if we said that the barn-frame observer says the > > > > > pole both fits and doesn't. But, despite you obfuscation and trying to > > > > > distract from what is actually being discussed .. that is not the case > > > > > It's not obfuscation. My arguments are perfectly reasonable. And my > > > > question is this: "does the ladder fit with both doors shut, or not?". > > > > It cannot fit and not fit at the same time. There are only two > > > > objects, ladder and barn. You can't say "according to the barn, it > > > > fits, but according to the ladder, it doesn't", because then you have > > > > two objects that disagree about their relationship with each other, > > > > and indeed make mutually exclusive and contradictory statements about > > > > their relationship.. > > > > Again, your problem (as anybody else here and everywhere clearly > > > understand the gedanken) is that you misunderstand basic physics. "A > > > nuclear blast happens" is the description of an EVENT. when you affirm > > > "It cannot fit and not fit at the same time" you are clearly wrongly > > > reading and understanding the gedanken. For it is quite clear that, > > > from the point of view of the 20 meters pole, it is impossible that it > > > fits inside a 4.37 meters barn. You see, the relevant events, which > > > have to be consistent, are the barn doors closing and opening. In the > > > barn frame of reference (FOR), both barn doors close at the same time > > > and they open at the same time (they are closed for 1 nanosecond). In > > > that condition the contracted 8.37 meters pole is, for a brief lapse > > > of time, inside a closed 10 meters barn. > > > In the pole FOR, the 20 meters pole sees the barn approaching at 0.9c > > > and the back door of the 4.37 meters barn closes and opens, just a > > > brief instant of time BEFORE the front of the pole reaches that > > > location (the 20 meters pole is at that time 4.37 meters inside the > > > barn). After that, the 20 meter pole sees the 4.37 meters barn front > > > door closing and opening, just a brief instant of time AFTER the back > > > of the pole just passed through that location (the 20 meters pole has > > > at that time 15.63 meters of its length outside the barn and its back > > > 4.37 meters inside the barn. > > > In both FOR, the 10 meter barn doors closed and opened and the 20 > > > meters pole did not touch any part of the barn. > > > Nice and easy. > > > Miguel, you seem to think that I don't properly understand the ladder > > and barn paradox. Let me correct you, I understand it completely. I > > can even tell you what would happen, working within the same tenets, > > if with careful timing you sent in *two* ladders in *opposite* > > directions, and shut the doors simultaneously (according to the barn > > frame) so as to contain both ladders for an instant with an > > interference fit. > > > What I'm questioning is whether this "paradox" actually reflects > > reality at all. It is easy to conceive of mathematical models that are > > internally consistent, ostensibly fit the existing evidence, but have > > no basis in reality - mainstream economics abounds with such models > > (and is widely regarded as being empirically discredited, and the > > maths regarded as obfuscatory). > > It is virtually unheard of in physics, despite your experience with > economics, that a model is internally consistent, fits the existing > evidence, and *continues to make accurate predictions of new > measurements*, and still has no basis in reality. In physics, a model > that is internally consistent and has a good fit to all known and > ongoing measurements is a GOOD model by operational assumption, until > such time as it begins to fail having a good fit to measurements. > > I notice your statement that there are many economic models that fit > the existing evidence and yet are empirically discredited. You can > imagine my confusion about that. > > > > > That leads on to my real question here. I'm not interested in being > > told *what* SR predicts - which is what you've done here again for the > > umpteenth time. I'm interesting in an explanation of *why* these > > predictions would be what they are. > > This will ultimately boil down to a couple of statements: > 1. Maxwell's laws of electromagnetism, as well as other physical laws > like them, work to accurately model reality, as evidenced by their fit > to experimental data. > 2. Physical laws all have the same form in any inertial reference > frame. > > Now, getting from these two statements to the conclusions of the > ladder and pole situation -- or for that matter, situations that have > been directly and unambiguously tested -- requires pages and pages of > exposition if done in words. It will take much less if done with > algebra. > > > > > > > > > To go back to the audio analogy again, a trivially easy equation > > determines *what* audio Doppler shift you will observe, but it does > > not explain *why*. Indeed, the equations in audio Doppler do not even > > tell you whether the source frequency really changes or not. To > > explain *how* audio Doppler works, and to rule out the assertion that > > the source frequency "really" changes, involves an awareness of each > > step in which mechanical energy is transmitted through air to the > > receiver. > > > That's what this discussion is about. Repeating the paradox does not > > help further *explain* the paradox, or answer any of my questions in > > regard of it. When I say "why does the other object always contract", > > I don't expect to be told "because SR says it does" - that is no > > explanation at all. > > > Jesus. -------------------- now parrot PD STE id right in his op question the second observers frame that moves perpendicular to the original lights line will get a Doppler shift !! because reasons you dont understand yet !! Y.Porat --------------------------
From: Ste on 7 Apr 2010 21:21 On 7 Apr, 22:45, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 7, 4:24 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > But you still don't get it. "Fitting" is not a relationship between > > obsever and ladder. It is a relationship between ladder and barn. Why > > on Earth would the observer's presence and circumstances affect the > > fitting of these two objects, that are totally independent of the > > observer? > > To help you understand this, I'd like for you to give me a very > precise definition of what you mean when you say that one object A > will "fit" inside object B, when A and B are relatively moving. > Depending on the quality of your definition, I may probe it with some > additional questions and scenarios to see if it works. It's relatively straightforward. "Fitting" is when the ladder is of such length that it would be possible to close both doors on the barn, and for the ladder to be contained completely inside. > > > > but that's not materialism - it's going > > > > back to saying that the tree falling in the forest only makes a sound > > > > if an observer heard it. > > > > Nonsense. You are the one who above pointed out the with the object moving > > > at 50km/hr and 100km/hr you have to consider the objects you are measureing > > > relative to (ie the frame of reference). > > > Yes. But you only have to reference two objects to describe a closing > > speed. You don't say "objects A and B were closing at 100kmh according > > to Jack" and "objects A and B were closing at 50kmh according to > > Jill", because that would be contradictory (assuming that the > > definition of "kmh" is itself common between Jack and Jill). > > > You could say "objects A and B were closing at 100kmh according to > > Jack" and "objects A and B were closing at 100kmh according to Jill", > > but since the observer has no bearing on the measurement, why > > reference him at all? > > But it does. Closing velocity is also frame dependent. > Suppose you have objects A and B, and you have observers Jack (at rest > relative to A), Larry (at rest relative to B), Mary (moving relative > to both A and B such that A and B have equal speeds relative to Mary), > and Nancy (moving relative to A, B, and Mary). I must admit I've no clear picture at all about this scenario. > Then what will be true > is that the closing speeds between A and B will have the same answers > for Jack and Larry, but that number will be different than the closing > speed between A and B according to Mary, and all of those different > than the one according to Nancy. No, I reject this. The closing speed between A and B is universal, no matter how the observers move around relative to A and/or B.
From: Y.Porat on 7 Apr 2010 21:22
On Apr 8, 12:01 am, no. And I suspect at this point the > > real problem is not my lack of understanding of the paradox, but your > > lack of understanding of what I mean by "real". > > Real is what can be verified by a measurement. -------------------- so why is it that an idiot like you claim that THERE IS NO SMALLEST PHOTON ENERGY !!! !?????? CAN AN IDIOT LIKE YOU MEASURE PHOTON ENERGY THAT IS LESS THAN PLANK TIME DURATION EMITTED ?? Y.P --------------------------------- |