Is Length Contraction in SR physical??
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From: PD on 9 Feb 2010 11:40 On Feb 8, 9:53 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Feb, 14:22, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 8, 9:10 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 8 Feb, 12:46, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > > wrote: > > > > > We seem to be getting somewhere now. I can basically understand the > > > > principle of how that carries out a detection. Now, do you have any > > > > data that plots detections and velocities, at different speeds? > > > > > ________________________ > > > > > "Plots velocities at different speeds"! > > > > > ROFL! > > > > The velocities of the decay products for different impact speeds, you > > > pillock! > > > > > The explanation of how the detector works actually explains how energy and > > > > direction are determined for several different particle types and classes. > > > > And *none* of it relies on shining beams of light at the particles. > > > > I never said it did. But in the case of tauons, it does depend on > > > measuring the velocities of decay products, so I want to know what > > > those velocities are, and how they change with speed. > > > Well, you can look up an experimental paper just as well as anyone > > else. Why is it up to us to find this for you? I wish I had someone > > to run around getting papers for me when I need them. > > As I explained to Paul Draper, I actually do that sort of thing for > people all the time on a variety of subjects, because the whole point > of claiming to have knowledge is that you share it. This I dispute. Surgeons don't have medical knowledge to share it. They have medical knowledge so that they can use it to make people healthier. Lawyers don't have knowledge of the law to share it. They have legal knowledge so that they can help represent people in courts of law so that justice is furthered. Plumbers don't have knowledge of building codes to share it. They have that knowledge so that they can install plumbing that is safe and works well. People have knowledge so that they can perform a service where expertise is an advantage. > > I've personally no idea how particle accelerators work, and so I don't > claim to know. If the truth is that you also don't really know the > answers to my questions, because you've never worked on a particle > accelerator, then that's fair enough, but then perhaps it will be a > lesson for you to be a little more modest about your scientific > knowledge. > > As I say, with particle accelerators relying heavily on > electromagnetism, I've no doubt that SR has a big application to its > workings. > > The question is whether the scientists who claim to understand SR > actually do understand it in a physical way, or whether they have just > learned the maths by rote and swallowed the fallacious explanations > they've been given for what they observe. Yes, I understand it in a physical way. It's just that what I include in "physical" is more than deterministic cogs and levers, you see. > And certainly, if the > opinions of "experts" here are anything to go by not to mention in the > literature, it is clear that most people who have studied physics ill- > understand the physical basis of the theories that they have learned. First of all, this group is not representative of the field of physics. At all. Please disavow yourself of that notion. Secondly, since you have a very specialized and persoanl meaning to the term "physical basis," it should not surprise you that physicists are not particularly perturbed by the accusation that they don't have what you would term a "physical" understanding. PD
From: mpalenik on 9 Feb 2010 11:58 On Feb 9, 3:45 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 9 Feb, 07:00, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 9, 1:57 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 9 Feb, 00:40, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 8, 3:21 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > On Feb 8, 3:57 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > Indeed, I have no information about how the decay products are > > > > > > measured in these accelerators nor access to the raw data set, and I'm > > > > > > not willing to take the word of scientific authority in which I have > > > > > > utterly no faith, particularly because so many supposed experts appear > > > > > > to have no insight whatsoever into the physical nature of their > > > > > > mathematical models, and even more shockingly the request for a > > > > > > physical explanation often produces the reply "what do you mean by > > > > > > physical", as though it needed to be defined! > > > > > > Well, here we run into the small conundrum: > > > > > S: "I don't see why I should believe this theory without a physical > > > > > model that makes sense to me." > > > > > P: "Well, you see, physicists choose which model to believe based on > > > > > which of the models matches the largest set of experimental data." > > > > > S: "But I don't believe the experimental data either, because I do not > > > > > trust that they haven't been skewed by physicists." > > > > > P: "What would it take for you to believe the experimental data?" > > > > > S: "It would require physicists to explain the data with a model that > > > > > makes sense to me." > > > > > > Self-fulfilling prophecy, you see. > > > > > What's really funny is that he had already decided there was a > > > > systematic error in all the experiments *before* reviewing any of the > > > > experiments. > > > > > Also funny is that he seems to think you can have a theory that > > > > "explains" SR while giving different numerical predictions than SR > > > > (such as the prediction of length contraction). One has to wonder in > > > > what what the two descriptions are equivalent if they predict > > > > different things. > > > > I've been clear about this. I have not turned my mind to the matter of > > > length contraction, I have simply made the statement, supported by > > > sources (including John Baez's site which was recommended to me), that > > > length contraction has never been experimentally verified.- Hide quoted text - > > > > - Show quoted text - > > > All I am saying is if your have a theory that does not predict the > > length contractions of SR, then it is not a theory that explains SR. > > It is a different theory. So, you either have to agree that length > > contractions as described in SR are correct or admit that your theory > > is fundimentally different from SR and not merely an interpretation of > > it. > > If it can be shown that the arguments I'm making about an absolute > aether require a length contraction, then I'd probably accept it, > particularly if a credible physical explanation can be given. > Otherwise, I reserve judgment - that is, I neither deny it nor accept > it. I don't care whether you accept it or not. The point is that without length contraction it is not the same as relativity. Even if by some miracle you ended up being correct, it still wouldn't be the same as relativity. It would mean that relativity is wrong.
From: PD on 9 Feb 2010 12:12 On Feb 8, 11:19 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Feb, 16:20, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 6, 11:33 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 7 Feb, 03:54, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 6, 8:52 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > The only thing that is required is to note at the detector X or the > > > > > > detector Y whether the signals from the events arrive at the same time > > > > > > or at different times. This is a point decision. It is a yes or no > > > > > > question. "Signal from A just arrived at X. Did signal from B arrive > > > > > > at X at the same time? Yes or no." > > > > > > If detection is instantaneous (i.e. if a photon is absorbed > > > > > instantaneously), then it is possible for A and B to be simultaneous > > > > > according to both X and Y. However, if detection is not instantaneous, > > > > > then it is *not* possible. > > > > > I didn't say "according to both X and Y". What I said in fact was the > > > > opposite. Please reread. > > > > What I did say is that X is *right* in concluding that A and B are > > > > simultaneous, based on the procedure we established as reliable. > > > > But the procedure isn't reliable! I've said that repeatedly. > > > It isn't reliable for what? > > For driving a consensus between X and Y? Is that a necessary > > requirement? Why? > > Let's revisit the procedure. > > If you were going to try to determine whether two events are > > simultaneous, according to a *particular* observer, then our suggested > > procedure is as follows: > > 1. Position a detector midway between the two events, where "midway" > > can be established at any time by directly measuring the length > > between the marks left by the events and the mark at the location of > > the detector. Let's amend this to say that this can be repeated on two > > occasions to determine that the "midway" condition has not changed. > > 2. Have the events send a signal known to travel with equal speeds > > toward the detector. The equality of the speeds can be established at > > any time by reproducing the signal and directly measuring the distance > > covered by the signal per unit time. > > (Note that (1) and (2) unambiguously determine that the propagation > > delay is the same from both events.) > > 3. Determine whether the signals from the events arrive at the > > detector at the same time or at different times. If the signals arrive > > at the same time, then from that information the correct conclusion is > > that the original events were simultaneous. If the signals arrive at > > different times, then from that information the correct conclusion is > > that the original events were not simultaneous. > > This works only if neither detector is moving. Moving relative to what? Notice that I said that the "midway" determination can be done at ANY TIME, and in fact repeated as necessary. Does this establish what you need? > > > You agreed earlier that this procedure should be sufficient for > > determining the simultaneity of spatially separated events, according > > to a particular observer. > > > Now you seem not so sure. What's the source of your sudden > > reservation? What procedure would you otherwise propose for > > determining the simultaneity of two spatially separated events? > > The source of my reservation is that equidistance cannot be > maintained, nor symmetry maintained, over the detection *interval*, if > the two detectors are moving relative to each other. Perhaps it would be best if we moved to an example. I'm going to use a modified version of Einstein's codification of these experiments. Two trains are on adjacent tracks, going in opposite directions, though I say that only to deliberately reinforce an ambiguity here. It doesn't matter whether the trains are going at different speeds, and in fact it isn't even important if one of the trains is stopped, or in fact whether they are going in the same direction but one faster than the other. All that matters is that there is a relative velocity between them. Two lightning strikes occur, drawn to the trains because of the friction of the air between the trains. In fact, one lightning strike leaves a scorch mark (a 1 cm spot, if you want to be precise) on *both* trains as it hits. The other strike leaves a scorch mark somewhere else on *both* trains. The question now is, were the strikes simultaneous or not? There is an observer on train A, and an observer on train B, and they are both looking out the window when the strikes occur. They make the following observations: 1. The observer on train A sees the two lightning flashes simultaneously. 2. The observer on train B sees the flash from the front of his train before he sees the flash from the rear of his train. Now, it is not yet possible to determine whether the strikes were simultaneous originally. We have more work to do. But I want to see if you have a picture in your head of what has transpired. > Even in an > idealised example where reception of the signal at the atomic level > occurs instantaneously (and I do not necessarily accept that even this > is true), no detection *system* (i.e. real world measurement device) > could perform a measurement of equidistance at the same time as > measuring the reception of the signal, and therefore no real-world > system can produce an observation of simultaneity where the detectors > are moving relative to each other. > > > > > > > > > Do you agree that those are the right conclusions, based on the yes or > > > > > > no question above, and given that the other conditions can be > > > > > > established? > > > > > > No. I think your mistake is in assuming that both the photon and > > > > > detector have an absolutely zero diameter (and therefore detection > > > > > occurs as soon as the surface of the zero-diameter objects touch).. In > > > > > reality, nothing in space will have a diameter of zero. > > > > > I don't know why you think diameter has anything to do with it. Note > > > > the size of the distance between A and X and between B and X. If a > > > > detector is 1.5 mm across, do you think this is going to be a dominant > > > > effect? > > > > No, I'm talking about the diameter of the photon and the atom. As I > > > say, the visualisation I have is somewhat like two bubbles in water, > > > and clearly if they are forced together so that they become one > > > bubble, that is not an instantaneous process. Certainly, the bubbles > > > do not merge merely at the first instant their (idealised spherical) > > > surfaces touch - they must be actually forced together until their > > > surface tension breaks. > > > > Having thought about it for a moment however, I realise that my > > > previous argument might not be wholly relevant or may be speculative > > > (although it embodies some likely factors that may be relevant in the > > > real world). You can theoretically (in particular, in the absence of > > > gravity) bring about absorbtion of photons from both events > > > simultaneously for both A and B, assuming that the photons and the > > > atoms maintain a constant speed as they impact and are absorbed by the > > > atom. > > > Let me ask you this. If your physical process can be established to > > take no more than, say, 2 picoseconds, and the arrival of the signals > > at the detectors is seen to be different by at least 2 microseconds, > > would it be established that the original signals were not > > simultaneous? > > Yes, *if* the assumption you make is true. Good, because this is *easily* achievable in an experimental set-up. > > Incidentally, does frequency have any effect on the absorbtion time of > electromagnetic radiation? No.
From: PD on 9 Feb 2010 12:15 On Feb 8, 11:26 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Feb, 16:24, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 6, 11:38 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > In Seto's case, it has more to do with thinking that SR says something > > > > it does not. I haven't yet figured out whether you are in the same > > > > boat. > > > > The only assumptions I make are those that have testable consequences. > > > > Which ones of those do you think I have that you reject? > > > > At least one of the assumptions to which I refer is that observation > > > reflects reality. > > > Science is about relationships between measurable phenomena, that is, > > the observed ones. > > If you believe science is about "real" properties which are > > unmeasurable but are nevertheless there, then I would ask how you > > would deduce anything quantitative about them, or in fact how you > > would test that your deductions are in fact accurate? > > Obviously it depends on the issue. What I would say is that my > hypothesis about the aether does have a theoretical test. In > particular, there should be a particular velocity at which measured > time runs fastest, and at all other velocities measured time should > run slower. This is not a test that distinguishes it from the predictions of other competitive models. Recall what I have told you earlier. > > > If you then > > claim that it is not necessary to test them, and is only sufficient to > > be reasonably certain that one's intuitions about them are correct, > > then I can pretty flatly say that what you are talking about no longer > > has any resemblance to science. > > We've discussed the philosophy of science extensively Paul. You have > yet to produce any coherent definition of "science" which is > constistent with the reality of how it is practiced. Nevertheless, what I've described in the paragraph above is disjoint from either a definition or practice.
From: PD on 9 Feb 2010 12:23
On Feb 8, 11:38 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Feb, 16:30, PD <thedraperfam...(a)gmail.com> wrote: > > > > > I don't know why you think that physical models MUST meet your > > criteria of "physical" (how YOU understand that term rather than how > > physicists understand that term) and "classical" in order to be > > acceptable to you. > > > Note that the REQUIREMENT you impose that the explanation be classical > > is simply an assertion that anything that does not meet the classical > > mold is not to be entertained as viable. This is a personal choice on > > your part that you will ONLY believe that which meets the classical > > physics mold and simply NOT BELIEVE anything else. > > I've been quite clear Paul. Everyone has axioms, everyone has > requirements. Untestable ones about the nature of the universe? Not so. > Stop framing the issue as though you, or "science", > don't. > > If "science" is happy to talk about "hidden dimensions", "multiverse", > etc, then fine, but it's no different from a belief in God. It *does* become different than a belief in God once you can isolate unique, measurable, and predictable consequences that MUST be observed under specified circumstances if hidden dimensions or multiverses are in fact true. In the case of God, there is a profound lack of unique, measurable, and predictable consequences that must be observed under specified circumstances. > I've been > quite clear that my requirements that something be "physical" means > that it has to appeal to physical and mechanical intuition. > > That is, my axioms are that the universe is naturalistic I have no idea what you mean by "naturalistic". > and > deterministic in nature - if yours aren't, then fair enough, there is > an irreconcilable difference between us - but as I say, there is > nothing "scientific" about your beliefs in the sense of "objective", Yes, there is. Objectivity does not mean "shared by all". It means independent of what humans think. This is where those isolated unique, measurable, and predictable consequences that MUST be observed under specified circumstances come in, you see. The fact that those results are determined by nature in experiment or observation, independent of what humans expect the outcome to be, is what provides the objectivity, you see. > and your appeals to scientific authority take the character of a > rhetorical appeal to the majority, except that theoretical scientists > are in fact a very small minority. Minority of what? Doctors are a minority as well, but medicine is not determined by what the majority of people think. It is determined by those who have become experts in medicine. That is the deliberate strategy of social specialization, you see. |