A constant speed of light in all reference frames? Surely you can't be serious.
in [Relativity]
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From: mpalenik on 17 Feb 2010 11:07 On Feb 17, 10:04 am, Ste <ste_ro...(a)hotmail.com> wrote: > On 16 Feb, 15:53, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Feb 16, 6:59 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > No we don't perceive a 3D world. We perceive a 4D world, and have done > > > since the beginning of time (as it were). That's what I'm saying to > > > you: the real world existed long before geometry. And geometry is just > > > a mathematical formalisation of basic concepts that were already > > > physically obvious to anyone who ever considered the issue. > > > You are quite right! But it turns out we've made some erroneous > > presuppositions about that 4D world. In fact, the presupposition we > > had has a fairly tight specification. We had the notion that the > > universe was structured as what's called a "fiber bundle" (it's a > > mathematical term), with 3 spatial dimensions and an *independent* > > time dimension. This expresses itself in certain ways. For example, > > two observers in relative motion can label coordinates in 3 spatial > > and 1 time dimensions in several possible ways, and it's possible to > > make diagrams that show those relationships. One possible way is the > > "fiber bundle" way that says that the distance between two events in > > space and time (x^2 + y^2 + z^2) will be the same for both observers, > > and this can be traced to the *independence* of the time dimension. > > Has time ever really been considered "independent"? It seems to me > that much of this "relativity of simultaneity" can be constructed with > reference only to acoustic phenomena. > > > > > Let's try it this way: what about the picture I drew for you do you > > > > not think could represent physical reality? > > > > I never said it didn't *represent* physical reality, at least in some > > > way. But my ability to understand requires me to translate that > > > representation into something physical and concrete. > > > You'll find that this chaining of representations to objects that you > > are already familiar with prevents you from discovering much that is > > wholly new and unfamiliar. > > As I've said before, I disagree that we ever see anything that is > totally "new and unfamiliar". > > > > But there is no such thing as a two-dimensional "flatland" in reality.. > > > This is much like saying "imagine a place that is not real with people > > > who are not real, and imagine what reality would look like to those > > > people" (which I can only say is unimaginable), and then using this as > > > some sort of proof of a "hidden reality" that is not apparent to > > > people who *are* real. As I say, the four dimensions have been with us > > > since the beginning of time, and people have in one way or another > > > recognised their physical existence since the beginning of time. > > > As we discussed earlier, it may be that we are only AWARE of four > > dimensions. It may well be that there are more. Then the way to > > entertain this notion is to ask the question, how would something that > > is only AWARE of two dimensions become convinced that there is a third > > dimension? This turns out to be very answerable. > > I'm afraid that was not my conclusion. As I've said, these > possibilities only seem credible to those who already hold them to be > credible. Well, how could they seem credible to people who don't hold them credible? Or do you think we were born knowing these things?
From: kenseto on 17 Feb 2010 11:13 On Feb 16, 2:04 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 16, 12:57 pm, kenseto <kens...(a)erinet.com> wrote: > > > On Feb 16, 1:46 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > Picking and choosing your definitions, Ken? > > > Look at the definitions I highlighted for you. > > > Look at your freshman physics textbook. Does it tell you that the > > > electric field is not physical? > > > In the past you insisted that length contraction in SR is physical and > > at that time you think that physical means material. > > No, sir, I *never* said length contraction was material. I said it was > PHYSICAL. > > > You even > > suggested that length contraction can be measured directly by shooting > > lasers from the ends of a moving ruler to the rest frame of the > > observer. > > Yes, it is MEASURABLE. Physical things are measurable. > Energy is MEASURABLE, it is not material. > Magnetic fields are MEASURABLE, they are not material. > Radio waves are MEASURABLE, they are not material. > > > So you see you think that length contraction in SR is > > material. > > No, it is MEASURABLE. It is not material. > > > Also your SR brother Inertial said in this thread that contraction in > > SR means that the atoms get closer....this means material contraction. > > Ken, rather than desperately trying to gather excuses to support your > mistaken impression, why don't you just take another look at the > correct definitions for physical that I've already shown you? Why > don't you reread your freshman physics text again, and check whether > it says the electric field is not physical? If you've made a small > mistake, then CORRECT IT and move on. If you cannot ever correct a > small mistake, you'll never get out of square one. You'll spend all > your time searching newsgroups for support for your mistake. > > PD I am tired of arguing with an idiot like you. Some ridiculus assertions made by you and some of your SR brothers are as follows: 1. In the pole and the barn scenario: SR claims that an 80 ft material pole is able to fit into 40 ft material barn but SR also made the contradictory claim that an 80 ft material pole is not able to fit into a 40 ft material barn. Inertial said that the atoms in the moving pole is closer together......this means material contraction but PD claims that this does not mean that the pole is materially shorter. Tom Roberts said that: it depends on what you mean by physical then follow by saying that "Generally, they would consider a "physical length contraction" to mean that the object ITSELF gets physically shorter. This is manifestly not so in SR." TR said in the past that length contraction in SR is a geometric projection effect ....much like a longer ladder is able to fit through a narrow door way. I agree that geometric length contraction is not physical or material contraction. PD claims that the pole is physically contracted but not materially contracted. He seem to have a new meaning for the term "physical contraction"...a meaning that is in between material length contraction and geometric projection length contraction effect. Notice that I didn't make any claim of my own...I am trying to find out which of the above assertions is the correct SR interpretation. 2. In the Bug and the Rivet Paradox: SR claims that the bug is alive. SR also made the contradictory claim that the bug is dead. 3. In Einstein's train gedanken: SR claims that the speed of light in the train is isotropic as measured by the observer in the train M'. However SR also claims that M' is moving wrt the light fronts from the strikes and thus M' should not be able to measure the speed of light to be isotropic. 4. A and B are in relative motion SR claims that A will see B's clock is running slow by a factor of 1/gamma and at the same time B will see A's clock is running slow by a factor of 1/gamma. Ken Seto
From: mpalenik on 17 Feb 2010 12:16 On Feb 17, 11:00 am, Paul Stowe <theaether...(a)gmail.com> wrote: > On Feb 17, 7:04 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > On 16 Feb, 15:53, PD <thedraperfam...(a)gmail.com> wrote: > > > > On Feb 16, 6:59 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > No we don't perceive a 3D world. We perceive a 4D world, and have done > > > > since the beginning of time (as it were). That's what I'm saying to > > > > you: the real world existed long before geometry. And geometry is just > > > > a mathematical formalisation of basic concepts that were already > > > > physically obvious to anyone who ever considered the issue. > > > > You are quite right! But it turns out we've made some erroneous > > > presuppositions about that 4D world. In fact, the presupposition we > > > had has a fairly tight specification. We had the notion that the > > > universe was structured as what's called a "fiber bundle" (it's a > > > mathematical term), with 3 spatial dimensions and an *independent* > > > time dimension. This expresses itself in certain ways. For example, > > > two observers in relative motion can label coordinates in 3 spatial > > > and 1 time dimensions in several possible ways, and it's possible to > > > make diagrams that show those relationships. One possible way is the > > > "fiber bundle" way that says that the distance between two events in > > > space and time (x^2 + y^2 + z^2) will be the same for both observers, > > > and this can be traced to the *independence* of the time dimension. > > > Has time ever really been considered "independent"? It seems to me > > that much of this "relativity of simultaneity" can be constructed with > > reference only to acoustic phenomena. > > > > > > Let's try it this way: what about the picture I drew for you do you > > > > > not think could represent physical reality? > > > > > I never said it didn't *represent* physical reality, at least in some > > > > way. But my ability to understand requires me to translate that > > > > representation into something physical and concrete. > > > > You'll find that this chaining of representations to objects that you > > > are already familiar with prevents you from discovering much that is > > > wholly new and unfamiliar. > > > As I've said before, I disagree that we ever see anything that is > > totally "new and unfamiliar". > > > > > But there is no such thing as a two-dimensional "flatland" in reality. > > > > This is much like saying "imagine a place that is not real with people > > > > who are not real, and imagine what reality would look like to those > > > > people" (which I can only say is unimaginable), and then using this as > > > > some sort of proof of a "hidden reality" that is not apparent to > > > > people who *are* real. As I say, the four dimensions have been with us > > > > since the beginning of time, and people have in one way or another > > > > recognised their physical existence since the beginning of time. > > > > As we discussed earlier, it may be that we are only AWARE of four > > > dimensions. It may well be that there are more. Then the way to > > > entertain this notion is to ask the question, how would something that > > > is only AWARE of two dimensions become convinced that there is a third > > > dimension? This turns out to be very answerable. > > > I'm afraid that was not my conclusion. As I've said, these > > possibilities only seem credible to those who already hold them to be > > credible. > > What I've seen here, and even in some books, is a vague improper use > of the term dimension. From what I can tell, the term is strictly as > used, a mathematical concept. See: > > http://mathworld.wolfram.com/Dimension.html > > It is often confused with the concept of physical properties such as > mass, length, time, charge. Since two of these (length and time) are > modeled using geometrical dimensionality this leads to the confusion. > Adding further to this is the unitary systems we assign to the > physical properties (kilogram, meter, second, Coulomb, ... etc.). A > dimension has no physical existence and a physical property has no > inherent unitary values, we must combine these concepts to make, > quantify, and describe physical systems and processes. > > As time goes on we get more creative on assigning the term. In > relativity where we have, > > dx^2 + dy^2 + dz^2 - ds^2 = 0 I'm not even going to get into what's wrong with the preceeding paragraphs. Someone else can correct you on that. I do want to point out, though, dx^2 + dy^2 + dz^2 - ds^2 = 0 is what you have in regular geometry. ds^2 is a length element squared. This is nothing more than restating: dx^2 + dy^2 + dz^2 = ds^2 in a different way. The path that light travels along can be shown to be: dx^2 + dy^2 + dz^2 - dt^2 = 0 but in general, we have dx^2 + dy^2 + dz^2 - dt^2 = ds^2
From: Ste on 17 Feb 2010 12:25 On 17 Feb, 15:41, mpalenik <markpale...(a)gmail.com> wrote: > On Feb 17, 10:19 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > > > On 17 Feb, 13:25, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > wrote: > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > >news:9b31d2c9-e699-41a8-a366-bc2f407ad017(a)o30g2000yqb.googlegroups.com.... > > > > > On 16 Feb, 13:53, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > > > wrote: > > > >> I never said it didn't *represent* physical reality, at least in some > > > >> way. But my ability to understand requires me to translate that > > > >> representation into something physical and concrete. > > > >> ___________________________ > > > >> A lot of people have trouble understanding abstract concepts. You > > > >> shouldn't > > > >> feel shy about this, but you may take it as a sign that possibly physics > > > >> is > > > >> not for you. > > > > > I don't have too much trouble understanding abstract concepts within > > > > their own terms, if I'm inclined to familiarise myself with them. But > > > > if the abstract concept is supposed to describe something physical, > > > > then I wouldn't claim to "understand" unless I could indeed translate > > > > it into something concrete. > > > > > Indeed when I say "I don't understand", I may sometimes be using it as > > > > a polite synonym for having actually made a judgment that "this theory > > > > is obviously ludicrous and unworkable as an explanation for the > > > > phenomenon that was to be explained". > > > > Well, its obviously not ludicrous, because it works. The experimental > > > evidence is overwhelming. That is seems ludicrous to you is because you > > > don't understand some key concepts; one is the mathematics, and the other > > > relates to the philosophy of science. > > > > I might add that I have never heard of anybody who understood the > > > mathematics but thought SR (or GR for that matter) as being "ludicrous"; if > > > you were somewhat less lazy or considerably brighter (or perhaps both) you > > > could learn the maths as well and by the time you have learned Maxwell and > > > Minkowski you won't think its ludicrous, you will think SR (at least) is > > > obvious. > > > > But alas, lazy and stupid, that is a recipe for being a crank, not > > > understanding science. > > > Just to remind you, I don't necessarily think relativity is ludicrous. > > Only the explanations here for why it works. > > Then you *really* won't like general relativity. I certainly won't like the inferences that are drawn from it.
From: mpalenik on 17 Feb 2010 12:30
On Feb 17, 12:25 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 17 Feb, 15:41, mpalenik <markpale...(a)gmail.com> wrote: > > > > > On Feb 17, 10:19 am, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 17 Feb, 13:25, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au> > > > wrote: > > > > > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > > >news:9b31d2c9-e699-41a8-a366-bc2f407ad017(a)o30g2000yqb.googlegroups.com... > > > > > > On 16 Feb, 13:53, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com..au> > > > > > wrote: > > > > >> I never said it didn't *represent* physical reality, at least in some > > > > >> way. But my ability to understand requires me to translate that > > > > >> representation into something physical and concrete. > > > > >> ___________________________ > > > > >> A lot of people have trouble understanding abstract concepts. You > > > > >> shouldn't > > > > >> feel shy about this, but you may take it as a sign that possibly physics > > > > >> is > > > > >> not for you. > > > > > > I don't have too much trouble understanding abstract concepts within > > > > > their own terms, if I'm inclined to familiarise myself with them. But > > > > > if the abstract concept is supposed to describe something physical, > > > > > then I wouldn't claim to "understand" unless I could indeed translate > > > > > it into something concrete. > > > > > > Indeed when I say "I don't understand", I may sometimes be using it as > > > > > a polite synonym for having actually made a judgment that "this theory > > > > > is obviously ludicrous and unworkable as an explanation for the > > > > > phenomenon that was to be explained". > > > > > Well, its obviously not ludicrous, because it works. The experimental > > > > evidence is overwhelming. That is seems ludicrous to you is because you > > > > don't understand some key concepts; one is the mathematics, and the other > > > > relates to the philosophy of science. > > > > > I might add that I have never heard of anybody who understood the > > > > mathematics but thought SR (or GR for that matter) as being "ludicrous"; if > > > > you were somewhat less lazy or considerably brighter (or perhaps both) you > > > > could learn the maths as well and by the time you have learned Maxwell and > > > > Minkowski you won't think its ludicrous, you will think SR (at least) is > > > > obvious. > > > > > But alas, lazy and stupid, that is a recipe for being a crank, not > > > > understanding science. > > > > Just to remind you, I don't necessarily think relativity is ludicrous.. > > > Only the explanations here for why it works. > > > Then you *really* won't like general relativity. > > I certainly won't like the inferences that are drawn from it. I have no idea what you mean by "the inferences that are drawn from it" but General relativity is a theory that states that the *cause* of gravity is curvature of spacetime. |