Is Length Contraction in SR physical??
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From: Ste on 5 Feb 2010 22:33 On 5 Feb, 19:48, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 4, 4:00 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > Ok, but now you've cut your own throat, because if the axiom was some > > unobservable phenomena, then you've just said it's reasonable to infer > > its existence from the conclusions/predictions that are drawn from it. > > Or have I misunderstood? > > It's ok to infer the existence of unobservables if it can be shown > that those unobservables lead to necessary and observable consequences > that are distinct from the necessary and observable consequences of > other models, with which the consequences can be tested in > experimental observation. I know this, but it's a complete backtrack on what you were earlier arguing Paul, namely that we should restrict ourselves only to the observables, and ignore anything that is not obseravble. Now you're saying that it's legitimate to infer the existence of unobservables. > > > > > Thus you are saying that > > > > > if science, by virtue of its methodology, confronts these propositions > > > > > against observable measurement and finds the propositions therefore > > > > > suspect, then there is something wrong with the scientific > > > > > methodology. > > > > > No, I'm saying that scientists are failing to apply their own > > > > methodology to itself. > > > > Not so. I told you what the methodology is. Science is in the > > > business of testing propositions by confronting the consequences of > > > those propositions against *observable* measurement. It is NOT in the > > > business of making certain uncontestable propositions. > > > I have a simple question, namely how is this scientific method > > falsifiable? And of course that means you have to start talking about > > *why* you follow this method - more on this below. > > The method itself is not falsifiable. The method is not presented as > an objective truth of nature, and so it does not warrant the same test > as its subject matter. More on this below. But how can the *result* of the method be more objective than the method itself? And indeed, if the method is not falsifiable, then what if someone argues that the "subject matter" is false because the method is wrong? It's like saying that, if we use a "fishing method", we always get fish to eat, so this "proves" that fish is all that exists. And yet, the results would be quite different if we used a "hunting method". > > > > > The difficulty, you see, is that there becomes an awfully soft line > > > > > between those propositions which need to be kept sacred and those that > > > > > don't. Indeed, that list of sacred propositions might vary from person > > > > > to person. And then, you see, it becomes rather difficult to declare > > > > > whether ANY of them are *truly* sacred, or whether science is in the > > > > > position to desanctify ANY of them. > > > > > "The inherent contradictions..." > > > > What contradictions? > > > I was alluding to the contradictions inherent in the philosophy of > > science. > > Well, that's still isn't very illuminating, now, is it? > > But at this point, we have drifted off into questioning whether > science as an activity is worth anything, or whether what it produces > is worth anything. That's fine. There are people who don't believe > that fine art does anything for mankind, and there are others for whom > politics (not to mention "political science") is a wholly and > intrinsically worthless venture. If you don't care for science or take > no stock in its method, then don't participate in it. I do care for science, but I'm having to wrestle against your assertions that what I'm doing is "not scientific". So far, I haven't heard a more credible definition of science than "what scientists do", and when you say someone is not doing science, you may as well just say "he's not one of us", which is clearly subjective ideological rhetoric, not an objective argument. > > > > > And that is not right. Science deals with things both material and > > > > > immaterial, where I am using the *physics* meaning of "material". > > > > > I'll remind you that the *physics* meaning of "material" is > > > > > "consisting of matter", where matter is defined as "substance which > > > > > has mass and occupies volume". (Now, you may have some other, rather > > > > > more vague definition of "material", but then your statement of > > > > > science being the investigation of the material world ends up lacking > > > > > any semantic content.) > > > > > So is physics not the study of space as well as matter? > > > > Yes, it is! And of fields, and of a number of things that are not > > > material by the definition of material used by physics. That's why I > > > say that physics is NOT the study of the material world. > > > Sorry I think I misread what you wrote. All I will say, then, is that > > the word "material" has a meaning outside of physics, and in > > particular in philosophy, that is somewhat less specific than the > > definition you hold. > > I understand that. I have a degree in philosophy. Ah, that explains why you're interested! :) > But we are not > talking about "material" as it is used in philosophy. We are talking > about "material" as it is used in physics, because we are discussing > what it is that physics studies. Fair enough, but as I've said, even physicists do not use scientific definitions consistently (partly because science is not compartmentalised from philosophy, etc), and it should be obvious from the context what a person means. I'm not even convinced that the definition you attribute to certain words are shared consistently by scientists, or that a outright majority of scientists use such words only according to their scientific definition. Indeed, you came up with the classic example of "string theory", which you could see violated your own apparent "scientific" definition of the word "theory". > > I'll make a note of your preferred nomenclature, > > but it's probably worth bearing in mind that many people (including, > > I'm sure, physicists) will often use the phrase "material world" to > > mean something much broader, and will generally encompass both matter, > > space, and everything in between. > > That's fine. You'll note that the broader, more colloquial use has > therefore vaguer and weaker semantic content, where the physical term > is quite precise and distinguishable from other concepts. You > expressed an intent earlier to translate what *physicists* mean by > words into what *you* mean be the same words. This should not incite > you to berate physicists for not sharing the colloquial, vague usage. I'm not berating them for using scientific terms. What I'm suggesting is that they should probably spend more time discussing the substantive issues if they already understand what is meant by the term (or, of course, they can ask for clarification). As I say, when I said "material world" or whatever, it's clearly that I'm using an inclusive definition. > > > If those do not, then science is simply not > > > concerned with them at all. This is why science has NO SAY on matters > > > of spirits, souls, and deities. > > > I dare say any self-respecting scientist is in competition with those > > concepts. > > I heartily disagree. If that were true, then no self-respecting > scientist could have religious faith. You'll find this is not the > case. Actually you're right. > > > > > Your inference of "real" properties independent of observed properties > > > > > has the same scientific verifiability as God, which is to say none. > > > > > But the scientific method itself has the same verifiability as God. > > > > You've just never thought about the philosophy of science enough to > > > > see the arbitrary assumptions that underpin it. > > > > The scientific method does not have a priori validity, nor does it > > > claim it. What it is is an *operational* convention that is adopted > > > because it has demonstrated success. > > > So in what way could it be falsified? And how can its success be > > discerned from other explanations, for example herd mentality? After > > all, it's not very "objective" if scientists, and *only* scientists, > > agree that their own method is the best. > > I just said that it does not have a priority validity over other > methods, nor does it claim to be able to demonstrate objective > superiority as a strategem. There is no proof that the scientific > method is the best method for acquisition of truth, nor does it claim > it without proof. Then science ends up saying nothing of meaning to people. > The scientific method's endorsement comes from productivity in > practice, The theoretical underpinnings of modern applied physics were mostly conceived before the 30s, and the modern philosophy of science was somewhat different then. Indeed, theoretical physics has barely moved an inch since science started restricting itself to "only what is observed", and started talking about things like "fundamental probability", etc. > compared to other methods tried. It has done a better job > than other methods for determining how nature works. To what other methods are you comparing the modern method? > This is not to > say that it can be PROVEN to be the best method possible. And in fact, > there are those who simply do not like the scientific method and do > not believe anything that scientists say, and there is no way to > convince them that they should. Nor is such an attempt made. But I'm *not* a person who dislikes science, and even *I'm* not conviced about many of the assertions that scientists are currently making, and nor am I convinced about many of the concepts that they are working with, for example extra dimensions, multiple universes, etc. > Those who are interested in pursuing science implicitly endorse the > scientific method because the method is the definition of science as > an activity, which is why it is called THE scientific method. Those > who want to use other methods for knowledge acquisition regarding the > universe are certainly welcome to do so. It just is no longer science. > That's what theologians and philosophers and mathematicians do, for > example. Just because you are talking about natural things does not > mean that what you are doing is science. Indeed, but the question is about defining what science *actually* is. It's not enough to say that "science is what scientists do", and learn the conduct by trial and error. If scientists want to have understanding for themselves, and legitimacy in the eyes of others, they must be clear about what they do - and every time a philosophical conflict arises, it's not good enough to just say "that's not science", which is really just a rhetorical appeal to a majority who are called "scientists". > > > It does not claim to be the best > > > or most universal method for knowledge acquisition. It is, however, a > > > method that has been adopted by a certain group of people (scientists) > > > under the operating assumption that it yields results. > > > Yes, so this "operating assumption" is axiomatic - scientists "have > > faith" that it has produced the best results so far, and will continue > > to do so. > > No, not even that. It is just the method that someone *chooses* when > one decides to be a scientist. So can one choose a different method when becoming a scientist? And what are the alternatives? And moreover, how do we choose between these methods? Is any method as good as another? > This is not necessarily contingent on > believing that it is the only or best way to understand nature. It is > just the way that is *chosen*. Indeed, but I'm sure you'll agree that "scientists" are going to get a shock in the future if they carry on choosing to believe their own versions of reality that no one else agrees with or can even understand.
From: Ste on 5 Feb 2010 22:38 On 5 Feb, 14:39, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > Then what part of SR requires that the effect be real instead of > merely observed? Isn't it more plausible to say that the *observed* > position of the ladder, doors, etc, are "rotated in time", but that > what is observed does not reflect physical reality? > ______________________________ > You don't seem to get it. > > The equations of SR are correct, do you agree with that? For example, do you > agree that particle accelerators built using SR correctly function? > > Well, that's all that physics aims to do, correctly predict the outcome of > every experiment. Indeed. But understanding the physical nature of these theories is necessary for scientific advance. I mean, you can teach any fool to follow rules that are already laid down. But the people who are coming up with the rules need to have genuine understanding. > Its up to you how you visualise the fact that time and space are interwoven. > One way which is helpful for people with some mathematics background and who > have spent more than a month studying physics was suggested by Minkowski. He > pointed out that the transforms between time and space were mathematically > identical to a rotation in 4D space with one imaginary axis, and that this > vector magnitude is a conserved quantity. How "physical" this vector and its > rotation actually are depends on your definition of physical. Indeed, > whether you want to interpret SR in this way is entirely up to you. Einstein > didn't use this in creating SR. I know, because Einstein, as best I can tell, thought like me, physically, and politically.
From: Ste on 5 Feb 2010 22:51 On 5 Feb, 14:41, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote: > >> ____________________________________________ > >> Perhaps if you defined what you mean by "physical sense" this statement > >> would have some meaning. > > > Speaking of "physical", I'm starting to wonder whether I've actually > > died and gone to hell for my sins, where the Devil has decided that I > > am to be tormented by having to explain the meaning of "physical" for > > all eternity. > > Just define it once. > > The only argument you seem to have is that it isn't "physical", and you > won't say what that means. There's no single word to sum it up really. "Physical" basically relates to "that which we can experience with our senses". It's something that exists independent of consciousness and thought. It's also deterministic, predictable, and orderly. Of course, I don't really want to get into an argument about whether you agree with this definition. > So you have no argument at all, and are just a > troll. Most people here think *anyone who doesn't agree* is a troll, and if I were a troll, one wonders why I'd go to this much hassle.
From: Ste on 5 Feb 2010 22:54 On 5 Feb, 15:44, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > On 5 feb, 01:29, Ste <ste_ro...(a)hotmail.com> wrote: > > What it is known is that no absolutes are needed, in order to predict > what the results will be on a given physical experiment. I contend the absolutes *are* needed in order to predict accurately. The fact that relativity suffices for present purposes is neither here nor there for anyone contemplating theoretical physics. > Take GPS, for > instance, where clock corrections on satellites, one based on SR and > the other based on GR, are enough to ensure the necessary precision of > the satellites clocks, by which the entire GPS system can perform as > predicted. Those corrections do not need or care of some absolute > reference frame located somewhere, far in the deep universe. Local > frames of reference do quite well and work like a charm. I think you'll find that even with GPS, there is a margin of error and empirical constants.
From: Ste on 5 Feb 2010 23:15
On 6 Feb, 02:36, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 5, 9:04 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > Your conclusion "no" is in conflict with experimental measurement. > > > When intuition conflicts with experimental measurement, then it is > > > intuition that must give way. > > > I checked Paul before I gave this answer. Length contraction has never > > been experimentally tested. So my intuition does *not* conflict with > > experimental evidence. > > Length contraction must follow for logical consitancy based on other > measurements. "Logical consistency" is a far cry from "experimental evidence". > If the speed of light is constant in every reference > frame, And it is my contention that it isn't relatively constant, but merely *appears* to be so. It is my contention that the speed of light is constant only with reference to an absolute frame, and that the time dilation effects are due to classical-mechanical effects on the velocity of photons. > length contraction must necesessarily follow, as we've > described it to you. That's how the original derivation of all of > special relativity worked. You apply logic to the two postulates of > relativity and see what it necessitates for consistancy. If the speed > of light is constant, E=mc^2 logically follows (or rather, E^2 = > p^2c^2 + m^2c^4), as does length contraction, time dilation, and the > differences is simultanaity. Can you admit this is the case? So > while length contraction may not have been experimentally measured > directly, what has been measured? But what if, for argument's sake, the speed of light is constant *only relative to an absolute frame*? And let us assume that the solar system is more or less still with reference to that frame. Can this assumption be made mathematically? And moreover, would SR still work *within the current margins of error* if this were true? > Ste, could you try doing the exercise that I posted in reply to Ken's > message? I missed that one. |