Known physics defeated by simple puzzle?
in [Relativity]
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From: PD on 7 Apr 2010 21:47 On Apr 7, 8:40 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 7 Apr, 23:01, PD <thedraperfam...(a)gmail.com> wrote: > > > On Apr 7, 4:39 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > 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. 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". > > > Real is what can be verified by a measurement. > > No it isn't. This is a fundamental difference between us. I dare say > there are lots of things that cannot be verified by measurement, but > only by inference from other measurements. Not that are of scientific interest, no. > > > If you believe that reality has certain traits but that those traits > > are unverifiable through measurement, because the measurement is > > always obscured, then one has to ask on what basis you would believe > > reality has those traits in the first place. > > Indeed, you would have to ask that. Yes, and appropriately so. I notice you snipped the next line, which I here repeat: =============================== If you then say, "Because it makes sense to me that it would," then you have simply slipped into subjective solipsism that is divorced from scientific investigation. =============================== And so there we are. > > > > > > > We all understand > > > > that. You don't know what you are talking about and it shows. > > > > When you build a model of the world such as Special Relativity, you > > > > consider some building blocks (the two postulates) and continue from > > > > there. You are really not interested in following that route, > > > > You're right. I'm not interested in merely reasoning from the first > > > principles of a particular theory, and then dusting off my hands and > > > patting myself on the back. > > > > I'm interested in seeing how this theory actually applies to the real > > > world, and how the conclusions of the theory are to be interpreted in > > > practice. For example, how "length contraction" is to be explained as > > > a matter of practical reality, and not just accepted at face value > > > "because the theory predicts it". > > > In terms of practical reality, length contraction applies to cases > > where there are high speeds involved, typically. Thus the length of > > the RF cavities in a LINAC changes as the particle accelerates, at a > > rate that is completely consistent with length contraction. > > Beyond my comprehension. > > > The same > > goes for where you place a detector to watch a particle decay, because > > time dilation of a fast moving particle means it will be further away > > from its creation when it decays than what would be expected from its > > speed and its rest lifetime. > > But how does that prove anything? Decay is measured statistically in > any event, and we have no understanding of the underlying mechanism > that causes decay. > > > Since the placement is critical for a > > successful experimental design, its an excellent example of practical > > application. For a living-room application, color TVs with CRTs are > > effectively electron accelerators that would get electrons to > > sufficiently high speed that you'd have to make a relativistic > > correction to the steering voltage to get the beam to sweep to the > > correct spot. Again, a practical application. > > Lol! I wasn't asking for "the practical applications of SR".
From: Sue... on 7 Apr 2010 21:49 On Apr 7, 9:39 pm, 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? > 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? > > > > > > > > > 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. According to SR not LET: Can the fast magician drop the small horizontal hula hoop over the long levitated lady as she zips across the stage at near light speed? He is an amateur magician who has yet to learn how to reattach heads and feet so don't be wrong. Sue... > >
From: Ste on 7 Apr 2010 22:04 On 7 Apr, 23:08, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 7, 4:57 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 7 Apr, 16:57, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Apr 6, 7:12 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > We've had this one before Paul. No experiment of this kind (i.e. > > > > trying to confine objects moving at relativistic speeds) has ever been > > > > performed. I even gave sources last time for this statement. > > > > That is simply not true. At RHIC, for example, where nucleus-nucleus > > > collisions are done, the density of the quarks and gluons goes up > > > precisely because of this Lorentz contraction. The nucleus is > > > "squashed" and the density goes up. This is essential to both the > > > design and the operation of this multimillion dollar facility. > > > > Furthermore, secondary particle emission from particle collisions have > > > been done in both fixed target and collider facilities. Under both > > > circumstances, relativity predicts the uniform distribution of those > > > secondaries according to a variable called rapidity. In experiments, > > > calorimeters are then arranged around the collision point and > > > segmented in regular rapidity bins. Naturally, because the two > > > experiments are viewing the same collisions from two different > > > reference frames, the length binning for equal rapidity bins is > > > considerably different, precisely because of Lorentz contraction. > > > Thus, the distribution by rapidity, as shown by the particle deposits > > > in the calorimeter, is an indirect but definitive check on Lorentz > > > contraction. Experimentally, the match-up is exquisite. > > > > It's unfortunate that your web references are not accurate on this > > > score, and have led you to the impression that Lorentz contraction is > > > all hypothetical and without experimental support. I will just > > > attribute this to the lack of depth of experimental information you've > > > been able to lay your hands on. > > > I really don't understand enough about how these machines work, and > > almost certainly never will, so it's pointless me attempting to > > reconcile what you say. All I will repeat is that a number of > > scientific sources, including a number of published scientific papers, > > have insisted that there has been no direct measurement of a physical > > length contraction. > > "Direct" is perhaps the key word. It is unfortunate that those papers > led you to the conclusion that it has not been experimentally verified > at all. I take no responsibility for confusion on your part that stems > from the limited selection of material you choose to read. Paul, I was quite clear, and was even clearer on previous occasions: there is no direct evidence. Quite simply, there have been no experiments where an object of a significant length has been accelerated and then a physical confinement attempted, with the outcome that if the object had not contracted, either the setup would noticably explode or it would be simply impossible to "shut the doors properly". I hadn't been led to believe anything except that the kind of experiment I describe above (in other words, one corresponding to the ladder and barn scenario) has not been performed. > > And indeed, whether there is experimental evidence > > or not, I still have not heard any compelling *explanation* for how > > two objects could each physically contract to a smaller size relative > > to the other. > > The definition of length is completely reliant on establishing > simultaneity. > Since simultaneity is frame-dependent, it is no wonder that length is > frame-dependent. Indeed. Except I've previously asked for simultaneity to be defined in a frame-independent manner - in the same way we talk of the "source frequency" in a frame independent way, instead of talking about the frame dependent "received frequency" > > > > But as I've said previously, even if this *is* what we would "see", > > > > seeing is not necessarily believing. > > > > And this is what I'm telling you is a bad policy in science. If > > > experiment comes in conflict with common sense -- that is, if what you > > > see is in conflict with what you understand -- then it is common sense > > > that should properly give way. I understand fully that you say you > > > just don't operate that way, and don't see why you should have to. > > > That's just absurd Paul. Insofar as you're contradicting that "seeing > > is not necessarily believing", your prescriptions would be a recipe > > for the trite regurgitation of observations, without any deeper > > understanding at all. If all we ever had to do in science was observe, > > and not interpret, then one wonders why it has taken so long to get > > this far. > > You have always maintained that there are always multiple > interpretations, multiple explanations that would apply to the same > set of data. I don't maintain that all are true (only one explanation can be true), but I concede that the limited data often admits more than one interpretation. > While this may be so in some limited sense, it is the > burden of the proposer of an interpretation to demonstrate that it is > the case with his own, complete with quantitative support. I'm not going back to discussions about the scientific method or 'on whom the burden of proof is placed'. > Furthermore, it has ALWAYS been the case that there can be isolated a > place where two different interpretations make DIFFERENT predictions > about what will be observed under certain circumstances. That, then, > is the place where the next experimental test is focused. This is > GUARANTEED to eliminate one or the other of the interpretations, and > this is how scientific progress is made. Who cares? You talk about testing as though every single debate ends in the parties saying "to the laboratory!" to test the theory. And anyway like I say, I'm not returning to a debate about the scientific method.
From: Inertial on 7 Apr 2010 22:12 "Sue..." <suzysewnshow(a)yahoo.com.au> wrote in message news:56c9fe57-49e7-4699-8542-43f273818b82(a)u31g2000yqb.googlegroups.com... > On Apr 7, 9:39 pm, 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? >> 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? >> >> >> >> > > > > > 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. > > According to SR not LET: No .. according to neither. Unless you are talking about the underlying Galilean/Newtonian 'reality' of LET that we cannot measure. > Can the fast magician drop the small horizontal > hula hoop over the long levitated lady as she zips > across the stage at near light speed? He is an amateur > magician who has yet to learn how to reattach > heads and feet so don't be wrong. :)
From: Sue... on 7 Apr 2010 22:18
On Apr 7, 10:12 pm, "Inertial" <relativ...(a)rest.com> wrote: > "Sue..." <suzysewns...(a)yahoo.com.au> wrote in message > > news:56c9fe57-49e7-4699-8542-43f273818b82(a)u31g2000yqb.googlegroups.com... > > > > > On Apr 7, 9:39 pm, 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? > >> 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? > > >> > > > > > 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. > > > According to SR not LET: > > No .. according to neither. Unless you are talking about the underlying > Galilean/Newtonian 'reality' of LET that we cannot measure. > > > Can the fast magician drop the small horizontal > > hula hoop over the long levitated lady as she zips > > across the stage at near light speed? He is an amateur > > magician who has yet to learn how to reattach > > heads and feet so don't be wrong. > > :) The magician's assistant thanks you for her life and as a token of gratitude has asked that your name be removed from the list of LET advocates. Sue... |