Known physics defeated by simple puzzle?
in [Relativity]
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From: Inertial on 8 Apr 2010 00:18 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:9eedbe0a-ae92-40f5-ab54-200ec53dcf75(a)8g2000yqz.googlegroups.com... > On 8 Apr, 00:50, "Inertial" <relativ...(a)rest.com> wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> > 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. >> >> 'interference fit' ? > > It's an engineering term. You know, where concrete reality counts. SO .. you're an engineer .. hence your inablity to think beyond what you know. >> > What I'm questioning is whether this "paradox" actually reflects >> > reality at all. >> >> Why shouldn't it? > > Because of the prima facie contradiction with reality, There is no contradiction with reality at all. What make you think there is? There is only a contradiction with your limited model of reality. One that has been long superseded. > and the > deficiency (and indeed absurdity) of the explanation offered. First you need to get some basic concepts and terminology .. and unlearn what you think you know for certain ..otherwise you can't understand, so there is no point in explaining. >> > It is easy to conceive of mathematical models that are >> > internally consistent, ostensibly fit the existing evidence, but have >> > no basis in reality >> >> If they predict what reality does, they are valid models > > A model can be valid and useful because it quantifies what you > observe. But it can be invalid insofar as it offers an explanation for > what is being observed. All a model needs to do is model. If you want an explanation, you first have to understand what the model says, and how what it is modeling behaves. >> > - mainstream economics abounds with such models >> > (and is widely regarded as being empirically discredited, and the >> > maths regarded as obfuscatory). >> >> > That leads on to my real question here. I'm not interested in being >> > told *what* SR predicts - >> >> Clearly you aren't. Which is your first mistake. >> >> > 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. >> >> Because that is how the geometry of the universe works > > Why not just say "Because. [full stop]"? It would have the same > explanatory value. So . you don't get the notion that the universe behaves how it behaves .. and that somehow it needs a reason for that . I suggest you turn to your nearest priest or philosopher. >> > 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. >> >> But you do not yet understand what SR says .. in particular about >> simultaneity. > > I understand what it says about simultaneity. No .. you don't. Your statements about it make that blatantly clear to those of us who do. > The problem is that I > think its definition of simultaneity is absurd. What .. that things happen at the same time? Nothing absurd about that. What YOU have issue with is that 'the same time' is not a universal absolute concept. >> You also use ambiguous and loaded terms like 'real' and >> 'subjective' in a deliberately confusing manner. > > No, I think it was accidentally confusing at first, but I've done > everything humanly possible since to clamp down on the meaning of > those words. Much simpler if you just DO NOT USE THEM. Their connotations are confusing you and making it hard for you to get past your preconceived notions.
From: Inertial on 8 Apr 2010 00:19 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:5eee3fd6-052a-491f-aeb1-5a8406608ca1(a)o30g2000yqb.googlegroups.com... > On 8 Apr, 02:39, PD <thedraperfam...(a)gmail.com> wrote: >> On Apr 7, 8:21 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> >> >> >> >> > 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. >> >> Remember the ladder is moving relative to the barn. >> How does one determine that the ladder is contained completely inside, >> exactly? > > By shutting the doors at the same time, of course. But 'at the same time' is not an absolute. You just assume (and insist) that it is. Experiment shows otherwise >> For example, I could shut one door and open it, while the front of the >> ladder is inside the barn, and then I could walk around to the back of >> the barn and shut the other door, while the back of the ladder is >> inside the barn. But by that time, the front of the ladder may have >> struck the first door. Is it still true that the ladder fits inside >> the barn? > > Indeed you could do this, but this would not prove that the ladder > "fitted". EXACTLY !! .. but that is what is happening in the ladder frame of reference. The doors do not close at the same time .. because 'at the same time' is frame of reference dependent.
From: Inertial on 8 Apr 2010 00:22 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:cc718293-e677-4b24-becf-991d154a4058(a)g10g2000yqh.googlegroups.com... > On 8 Apr, 02:41, PD <thedraperfam...(a)gmail.com> wrote: >> On Apr 7, 8:21 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > On 7 Apr, 22:45, PD <thedraperfam...(a)gmail.com> wrote: >> >> > > 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. >> >> Try making a sketch. > > No, what I meant was that there isn't sufficient information for me to > confidently build a mental sketch. There is > You don't describe how anything is > moving relative to anything else, or where anything is positioned > relative to anything else. Doesn't matter .. make a sketch that satisfies the conditions > And there are six (linguistic) objects in > total positioned and moving in non-specified ways, and also it is not > clear whether the observers should participate as real objects, or > merely oversee as God-observers. Of course, I could make assumptions > about these things, but if it comes to a disagreement, I don't want to > be arguing over a scenario of which there is no shared comprehension. Start with the assumptions and see how you go. Make a concrete example of the scenario described. >> > > 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. >> >> I don't care whether you reject it or not. It is experimentally the >> case, according to measurements. By what right do you say that >> something is true, despite being counter to measurements? We're back >> to unconfirmable solipsism if you so insist. > > The accusation is that the observations are being misinterpreted, They aren't > not > that I'm simply pretending the observations don't exist. So you think its all just an illusion .. and that reality 'really' works the way you want it to, and there are just some illusions that we call measurements that behave as SR models. This is what LET posits is the case.
From: Inertial on 8 Apr 2010 00:26 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:8ea0aa5e-65c3-487f-9ff2-94ae2acdf403(a)k13g2000yqe.googlegroups.com... > On 8 Apr, 02:46, "Inertial" <relativ...(a)rest.com> wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> >> > 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 >> >> which is a frame-dependent notion >> >> > that it would be possible to close both doors on the barn, >> >> implicitly simultaneously, which is a frame-dependent notion >> >> > and for the ladder to be contained completely inside. >> >> So it is a frame dependent notion. Yet you insist it be absolute and >> invariant. Sorry, but you cannot impose your will on nature or physics. > > But I do have a right to specify how my own hypothetical experiments > will be carried out. not really .. if you are trying to discuss the real world. If you want a fanciful world where Galilean / Newtonian physics is absolutely correct, then find .. But don't then say that it applies to the world we live ing. > And in particular, I have a right to determine > that my own definition of simultaneity will be used, Not really .. but we'll let that slip > and what is > simultaneous according to my definition may not be what you consider > simultaneous. From what I see of your definition, it is equivalent .. and so also frame dependent. Can you provide a more detailed description of your definition of simultaneous, so I can validate whether it is, or is not. equivalent. Or if it is differen,t in what way, and dos it actually 'work'. >> >> > > > 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. >> >> Its not that hard. Here's a more concrete example. Two relatively >> moving >> spaceships A and B. Jack is in one of them, Larry in the other, and Mary >> is >> in a space station half way between them. Nancy is in another rocket >> ship >> moving relative to all of them. > > So we'll just say there are four observers, each occupying real > spaceships. Let's just call them A, B, C, and D. We have A, B, and C, > on a common axis, in that order. A is travelling to the left of B. C > is travelling to the right of B. A and C are travelling away from B at > the same speeds (hence the speed between A and C is twice what is is > between A and B). Yeup .. that will do > D we can have travelling perpendicular to the axis at B's location, > again at the same speed as between A and B. > > Is that agreed? If you like. We'll see if PD agrees that this is ok for his purposes.
From: Ste on 8 Apr 2010 00:29
On 8 Apr, 01:28, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > (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. I wouldn't necessarily say that. I could make the statement objective, and simply say "we are moving at speed x with respect to each other". Then there is no contraction, because we each use those words and agree on the meaning. > > There's no point saying "because of SR" - that > > is no explanation at all. > > Because that is how the geometry of the universe works. That's putting the cart before the horse, is it not? SR is what needs an explanation. If you don't actually know what underpins SR, why don't you just admit it, and say "These equations quantify our observations accurately. I don't know why the equations work, but they do." Then you're not representing yourself as having knowledge that you don't really possess. After all, the average person would probably have to admit "I know how to switch on a light bulb. I know nothing about how electricity works, only that it does, and I know nothing about how the light is connected to the switch, only that it is." > 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. But I haven't said that "time is unaffected". I readily concede that time intervals (as between ticks of a clock, for example) can be distorted due to a finite speed of propagation, and I also readily concede that some effects (like impulse and gravity, and possibly movement through space itself) seem to cause or contribute to a genuine slowing of the fundamental processes of nature. I'm quite at home with time being affected, as long as I understand *how* it is being affected. But every plausible explantion offered, every avenue introduced to you, is rebuffed, and you insist that the effects of relativity are accounted for by no mechanism I've mentioned, but at the same time you don't propose any understandable mechanism yourself - you merely affirm the truth of relativity. > > - 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 No, no, no, no, no. No two observers disagree about the relative speed between any two specific objects. I've already explained this at length. > > 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. I never said it did have any "effect on space or time". I said that, if we *hold* that the clocks are accurate, then our measure of time becomes distorted. But at least in my example, the observer's "mind" will not have slowed down with the clock. But to go beyond my analogy (and to explicitly derive the point that I thought was obvious), if at the same time as both clocks slowing down, both observer's *brains* slowed down as well (as well as every physical thing around them), *then* what would they say. Even if they used their internal pacing of time, they would not notice the slowing of the clock or anything else local to them. The only thing that they would notice is that the whole rest of the universe suddenly started to change a lot faster - suddenly time seemed to be going faster *everywhere else*. Except it isn't. It is the observer who has slowed down, as well as his clock. > > 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 I know, I'm already snipping vast amounts of repetition. > > 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. No, we're not talking about any observers. > > 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 We're not talking about any frame of reference. > > 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 Only if you are asking "at rest wrt the frame". If you're asking whether something is at rest wrt to another object, then that is frame independent. > >> > 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. This is just mathematical waffle. You mean there are an infinite number of arbitrary values with which we can describe the same real velocity? > >> > 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. Then why can I describe the speeds without making reference to any frame, other than the two objects themselves? > >> > 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 We don't have to rule out SR. Merely *reinterpret* it. > > 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. I can understand the notion of getting "different values". I can say the room is 20 degrees C, or what, 68 degrees F. But I'm describing the *same* real temperature, but with different numbers (because I'm referencing different scales). The problem here is that the "real" relationship, of "fitting", is being described in two mutually exclusive ways. > 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. Lol! I don't see why simultaneity cannot be "absolute". Simultaneity is itself an inherently relative measure (i.e. you're asking about the time interval *between* two events). But that measure ought to be invariant across frames, in the same way it is for distance and velocity. > > 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. Lol. It does not change my conclusion, that the difference in numerical values conceals the fact that there is no change at all in the "real" properties being measured. |