Known physics defeated by simple puzzle?
in [Relativity]
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From: Ste on 7 Apr 2010 19:35 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. > 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.
From: Inertial on 7 Apr 2010 19:41 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:9d92fd3c-239e-4c42-850e-a25dad009fbf(a)i25g2000yqm.googlegroups.com... > On 7 Apr, 16:59, PD <thedraperfam...(a)gmail.com> wrote: >> On Apr 6, 7:27 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> >> >> >> >> > On 6 Apr, 19:44, PD <thedraperfam...(a)gmail.com> wrote: >> >> > > On Apr 5, 10:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > > > > You still haven't answered why 'fitting' must be absolute >> >> > > > Because of the obviousness of the concept. A thing cannot fit and >> > > > at >> > > > the same time not fit, because there is a logical contradiction in >> > > > the >> > > > meaning of those words. And nor can the state be subjective for >> > > > each >> > > > observer, otherwise that isn't materialism (and it isn't causal >> > > > either). Or to repeat my earlier analogy, you can't hit a person >> > > > over >> > > > the head with a hammer, and merely daze him *at the same time as* >> > > > cracking his skull wide open. >> >> > > This business about a thing fitting and not fitting being a >> > > contradiction... >> >> > > A penny on the armrest of a plane is at rest in one reference frame >> > > and not at rest in another reference frame. Is it not obvious to you >> > > that there is a logical contradiction in those claims? >> >> > No, because *everyone* agrees about how the penny is moving with >> > respect to any other object. >> >> But motion is not defined with respect to another object. It is >> defined with respect to a coordinate system, a reference frame. > > Then perhaps therein lies the problem. Ultimately, all "reference > frames" ultimately anchor to real objects, but "reference frames" are > not a physical entities in themselves. As I've said, I have a > practical turn of mind, so I'm always careful to understand how > abstract concepts relate to something real. > > > >> > > How does the >> > > penny change from being at rest in one frame to not being at rest in >> > > another frame, without there being some physical interaction with the >> > > penny to cause that change? >> >> > Because it *doesn't* change from being "at rest" to "not at rest". >> > There is no "change" at all. Both the man on the plane, and the man on >> > the ground, agree that the penny is stationary relative to the flyer, >> > and moving relative to the man on the ground. The penny does not >> > "change" from being stationary to moving. What changes is the object >> > to which you are making reference. >> >> I'm not making reference to any object. The motion of an object is >> with regard to a coordinate system, a reference frame. This is basic, >> high school physics. > > As above. A "reference frame" is still a reference object > (linguistically). And what we really mean by "reference frame" is that > certain real objects have defined mathematical values for their > properties (like defining certain objects to be at rest, and facing a > certain direction), and the values of all other objects are calculated > in relation to that. > > But certainly, there is no need to make reference to a "frame" in > order to calculate a "relative speed" between two objects. And the > point is that, those relative speeds between any two objects are the > same in all frames, even though the speed of any one object relative > to the frame is not. And an object can have different velocities relative to different objects (different frames of reference) at the same time. Hence velocity is not 'real' by your definition. If you think it SHOULD be real, you need to change your definition accordingly.
From: Inertial on 7 Apr 2010 19:45 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in message news:c4290ebd-228b-4d6d-a3ac-c7306caf177d(a)n34g2000yqb.googlegroups.com... > On Apr 7, 6:18 pm, PD <thedraperfam...(a)gmail.com> wrote: >> On Apr 7, 5:09 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> >> >> > On 7 Apr, 16:59, PD <thedraperfam...(a)gmail.com> wrote: >> >> > > On Apr 6, 7:27 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > > > On 6 Apr, 19:44, PD <thedraperfam...(a)gmail.com> wrote: >> >> > > > > On Apr 5, 10:03 pm, Ste <ste_ro...(a)hotmail.com> wrote: >> >> > > > > > > You still haven't answered why 'fitting' must be absolute >> >> > > > > > Because of the obviousness of the concept. A thing cannot fit >> > > > > > and at >> > > > > > the same time not fit, because there is a logical contradiction >> > > > > > in the >> > > > > > meaning of those words. And nor can the state be subjective for >> > > > > > each >> > > > > > observer, otherwise that isn't materialism (and it isn't causal >> > > > > > either). Or to repeat my earlier analogy, you can't hit a >> > > > > > person over >> > > > > > the head with a hammer, and merely daze him *at the same time >> > > > > > as* >> > > > > > cracking his skull wide open. >> >> > > > > This business about a thing fitting and not fitting being a >> > > > > contradiction... >> >> > > > > A penny on the armrest of a plane is at rest in one reference >> > > > > frame >> > > > > and not at rest in another reference frame. Is it not obvious to >> > > > > you >> > > > > that there is a logical contradiction in those claims? >> >> > > > No, because *everyone* agrees about how the penny is moving with >> > > > respect to any other object. >> >> > > But motion is not defined with respect to another object. It is >> > > defined with respect to a coordinate system, a reference frame. >> >> > Then perhaps therein lies the problem. Ultimately, all "reference >> > frames" ultimately anchor to real objects, >> >> This is not true. >> >> > but "reference frames" are >> > not a physical entities in themselves. As I've said, I have a >> > practical turn of mind, so I'm always careful to understand how >> > abstract concepts relate to something real. >> >> This should not lead you to therefore insist that reference frames by >> definition anchor to real objects, whether you want that to be the >> case for practical sensibilities or not. > > Remember... You have given up LET for SR > so rulers are not dependent on inertial frames. Never supported LET in the first place. Although the math is the same. > Minkowski Space > http://www.bartleby.com/173/17.html Fine > I can tape a metre stick to a gun barrel and > that is a proper clock. > > K.E. = 1/2 mv^2 > > The hijackers of the world would be interested > to hear from you which inertial frame most > slows the clock and weakens the lawmam's > bullet. You misunderstand (not surprisingly). A clock is measured as ticking slower by relatively moving observer, and a ruler is measured as having a shorter length by a relatively moving observer. There is no inherent change to the clocks and rulers themselves itself. And invariant intervals remain invariant (obviously). We are talking SR here, and not LET.
From: Inertial on 7 Apr 2010 19:50 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:2557821b-cb24-432b-bfb0-6d501fb5edac(a)q15g2000yqj.googlegroups.com... > 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. That is certainly obvious, as you do not understand simultaneity in SR, and the ladder and barn scenario depends on that notion > Let me correct you, I understand it completely. BAHAHAH > 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' ? > What I'm questioning is whether this "paradox" actually reflects > reality at all. Why shouldn't it? > 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 > - 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 > 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. They do. > 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. You also use ambiguous and loaded terms like 'real' and 'subjective' in a deliberately confusing manner.
From: Inertial on 7 Apr 2010 19:52
"Ste" <ste_rose0(a)hotmail.com> wrote in message news:0df9d7df-def4-4996-8416-4863b36acb58(a)g30g2000yqc.googlegroups.com... > On 7 Apr, 20:57, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: >> On 7 abr, 14:47, 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). >> >> > 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. >> >> > 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. >> >> I doubt that after writing "It cannot fit and not fit at the same >> time" you really understand this gedanken at all. > > It depends what you mean by "understand". If you mean "have grasped > its tenets, and can reason the conclusion from those tenets", then I > understand it totally. No .. you haven't > If you mean "accept that length contraction > really occurs", then the answer is 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". Then stop using such ambiguous and loaded terms. You have been given the appropriate terms to use. |