Is Length Contraction in SR physical??
in [Relativity]
|
Prev: Simultaneous events and Einstein's absolute time
Next: New Theory --- The Theory of Quantum Wave Sources
From: glird on 9 Feb 2010 15:03 On Feb 9, 1:35 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > Anything that is within our physical experience has 3 spatial >dimensions.. Insofar as space is concerned, a "dimension" is just a direction we wish to measure. Although the minimum number of directions we need to use in order to specify the location of an object wrt a given referent is three, that doesn't mean that there are only 3 of them, Indeed, there are an infinite number of differently directed lines that may be appointed as "spatial dimensions". glird
From: PD on 9 Feb 2010 15:18 On Feb 9, 12:35 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 9 Feb, 17:46, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > It is fairly easy to demonstrate the tenets of Euclidean space. If you > > > give someone a supply of rulers, and tell them to describe a place by > > > using the numbers on the rulers, then it becomes fairly obvious that > > > you need rulers in 3 axes. > > > No it doesn't. It needs three rulers along the space that we are > > *familiar with* on the spatial scales that we are *familiar* with, > > which means laying rulers down that are longer than, say, a few > > nanometers and shorter than, say, a few hundred kiloparsecs. > > > This is the point. If the universe were shaped like a thread, then we > > would say that there is only one ruler needed, because there is only > > one dimension to follow, forward and back. > > No we wouldn't, because there is no such thing as a one-dimensional > thread - at least, not in our experience. Anything that is within our > physical experience has 3 spatial dimensions. Within our experience. But that's the point. Just as someone who is much larger than the mite would not be able to be SURE that the universe was one-dimensional (as he saw it) or two-dimensional (as the mite saw it), we cannot be SURE from our scale of observations that the universe only has 3 dimensions. Perhaps it has another that only a mite would see. Perhaps it has TWO others that only a mite would see. And this becomes the point of experiment. Is there a scale domain where we can be as perceptive as the mite in this allegory, so that we would begin to discern the presence of extra dimensions that are not obvious at this size scale? > > > But to a mite, that thread > > becomes a cylinder, and that second dimension -- going AROUND the > > cylinder -- earns its own ruler, even if it ends up being a closed > > path around the cylinder. What is obvious on one size scale is not so > > obvious on another size scale, you see. > > This seems to be just a statement that the universe "works in a > different way" at some scale, whereas I reject that view. It's not up to you to reject. There is plenty of precedence to show that this insistence on scale uniformity is a bad idea -- we've learned that lesson on both large and small scales. The only sensible thing is to try to find a way to *see if* there is evidence that the universe works differently at much different scales. > If we are > free to simply define arbitrarily the areas where the universe "works > in a different way", then I dare say any explanation will do Not at all. Any explanation would have to provide distinct, quantitative and accessibly measurable consequences that would be a signature of this change in rules. Moreover, there is a fairly tight constraint that if there is a scale where things begin to behave differently, then there is a continuum of correspondence between the behaviors -- that is, one description at one scale has to seamless blend into the other description at other scales naturally. I could give you an example, but I'd have to show the correspondence mathematically, or I'd have to point you to some visual figures in a book you'd have to look up in the library. > - and if > I remember correctly, that is precisely the problem with string > theory, that it is unfalsifiable because it has so many degrees of > freedom, which are inconceivable except in mathematical terms. Which is why scientists are loathe to call "string theory" a theory except for the sake of popularizations.
From: PD on 9 Feb 2010 15:22 On Feb 8, 2:28 pm, NoEinstein <noeinst...(a)bellsouth.net> wrote: > On Feb 2, 10:52 am, PD <thedraperfam...(a)gmail.com> wrote: > > Dear Readers: PD, the Parasite Dunce, is incapable of learning > anything. He used to be a teacher (big deal). Yet, he can't accept > that the kinetic energy equationwhich inputs velocity UNIFORMLYcan't > have a resulting KE increasing exponentially, or KE = 1/2 mv^2, We've been through this. 1/2 mv^2 is not an exponential increase. You seem to have forgotten lesson you were taught just a couple weeks ago. Did you undergo some mental reset? Is it connected to medications? > according to Coriolis's errant formula. Einstein based his SR on the > latter KE equation, but he dropped the 1/2, for some unexplained > reason. Both the equations of Coriolis and Einstein, in his SR, > violate the Law of the Conservation of energy, by GETTING OUT more > energy than is being put in by velocity. PD considers that distance > traveled is a 'free' energy component of velocity. But find KE > wherever he may, both Coriolis and Einstein still violate the Law of > the Conservation of Energy. If the Coriolis equation was correct, > then WHERE does the exponentially increasing energy come from? From the work provided by an externally applied force. We've been through this before too. Do you start fresh every day, forgetting everything that happened yesterday? Because if you do, then I see no point in repeating myself over and over to you. > > NoEinstein > > > > > On Feb 2, 9:40 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 1 Feb, 20:52, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 1, 2:49 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > So does that mean that length contraction is not physical? > > > > > No, it does not mean that. > > > > Why do you think that "observer dependent" means "not physical"? > > > > Lots of physical properties are observer dependent. > > > > Because for anyone who believes in material reality, physical > > > properties should not be "observer dependent", > > > Then I would ask the following questions of you. > > Is velocity a physical property? It is *clearly* observer-dependent. > > Having answered that, is kinetic energy a physical property, given > > that (at least at low speeds) the kinetic energy is proportional to > > the square of the velocity, and so is also clearly observer-dependent. > > Having answered that, is the law of conservation of energy, which > > includes kinetic energy as one of the contributions to the conserved > > sum, a law about physical properties? If not, then what is it a law > > about? > > > > and if physical > > > properties do indeed seem to change depending on how they are > > > observed, then there should be some coherent explanation for it rather > > > than just a statement that things are "observer dependent", which in > > > most people's minds rather leaves the glaring question "why". > > > I think there may just be a clash regarding an unfounded expectation > > that physical properties "should" be observer-independent. Why would > > this be an expectation? > > The reality is that physics is littered with physical properties, > > about which there are many laws that seem to hold remarkably well. > > Some of those properties are observer-dependent, and some are observer- > > independent. There is no rationale required for "why" they are not all > > one way or the other, any more than there has to be a reason cited for > > "why" all animals are not mammals. > > > PD
From: PD on 9 Feb 2010 15:29 On Feb 9, 12:37 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Feb, 17:01, PD <thedraperfam...(a)gmail.com> wrote: > > > On Feb 6, 11:48 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > Ah, but the difference is I *will* discuss my views, I'll discuss them > > > on each and every occasion someone expresses a legitimate interest in > > > discussing them, and I'll generally continue to discuss them until > > > either one of us changes our views, or until the other person gets > > > tired. > > > But you've already established that it won't be you that might change > > your views. > > It's unlikely I'll change my axiomatic beliefs, but I'll certainly > hold my hands up and shut my mouth if it turned out that what I'm > saying is simply illogical. I'd like to expand the range of possible outcomes. It's possible that what you're saying is completely logical but still wrong, where "wrong" means "does not describe our universe accurately or in a scientifically useful way". Literally hundreds of perfectly logical and mathematically consistent ideas are published every year that turn out to be wrong. The temptation is to ask, if it's wrong, then where is the logical defect? There doesn't need to be one. The absence of a logical defect does not guarantee that it's right. > > > As for your insistence that you should be able to expect an education > > suitable for the "ordinary man" at the hand of physicists on a > > newsgroup, in order for you to change your views, then I think on that > > too you will guarantee your own failure. > > That's not what I said Paul. I said the essence of these theories > should be such that an ordinary man can understand it. I mean, I don't > pretend to be able to plot a trajectory through the solar system, but > I understand the basic concepts, and indeed have done so since I was a > child. And an ordinary man CAN understand it. Just not in a few sentences or on this venue.
From: PD on 9 Feb 2010 15:52
On Feb 9, 12:46 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 8 Feb, 20:21, 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." > > And indeed, I don't believe mere *assertions* that the experimental > data supports a theory that is contrary to my axioms. Nor would I expect you to. Indeed, I would expect you to go to the library to read the experimental papers yourself, so that you can see all the cards laid out on the table. > > > 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. > > Indeed, but I'd already identified that the problem is axiomatic. > Without putting too fine a point on it, I require a physical, > mechanical explanation, and you're right that I would not consider > something an explanation unless it meets those requirements. And herein lies a barrier for you that does not exist for physicists. Nor should it. > > That said, this goes back to what I said at the start, and indeed what > Einstein said, which is that it is the theory that determines what you > can observe, because it is the theory that determines what is evidence > and how it should be interpreted. And this statement is, as I've told you before, looked upon askance by scientists. It is generally regarded as one of Einstein's less insightful statements, as it were. > If it is your argument that the > physical world cannot be understood except in your terms, then my > argument is that you haven't tried hard enough to understand it in any > other terms, and indeed you haven't. I have several comments about this last statement: - I see no reason to adopt a constraint that YOU have chosen to adopt, in the form of certain inviolable statements, if models are still testable without those constraints. - You have chosen to demand that any acceptable theory must respect certain chosen axioms. Scientists do not take as a charge to find models that work *within the scope of a chosen set of axioms*. It is their charge to find out how nature works, independent of what choices of axioms we may have chosen. This means that any set of axioms that have been adopted provisionally are still subject to revisiting. - As I've mentioned before, your chosen set of axioms may not coincide with another "ordinary man's" chosen axioms. I see no reason why it should be a charge of science to present one model that fits one man's chosen axioms and another model that fits another man's chosen axioms. - I'd like to underscore the point that much of the thinking that you've done in the last month is interesting and not rejectable out of pocket, but nor are they new. As you've gone through and discovered things like Lorentz Ether Theory, it may have (or should have) occurred to you that other people have already felt as strongly as you, and were also skill-equipped enough to develop those intuitions into real, testable theories. And it should also occur to you that if people have been thinking about these things for a century, then several of the attempts to make it work in a classical framework have also been tested experimentally. And so the *primary* skill you should develop is to learn how to find out who has already trodden the paths you are treading, and what the consultation with nature about those paths has yielded. PD |