According to 1905 Relativity, a single material point must be always at rest
in [Relativity]
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From: Androcles on 24 May 2010 02:44 "blackhead" <larryharson(a)softhome.net> wrote in message news:70a4084b-2807-4b96-8581-028720ba39c1(a)m21g2000vbr.googlegroups.com... On 23 May, 01:45, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "blackhead" <larryhar...(a)softhome.net> wrote in message > > news:23dacda0-1876-4750-a477-8ea0a987b6b4(a)j27g2000vbp.googlegroups.com... > On 22 May, 02:19, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > > > > > > > "blackhead" <larryhar...(a)softhome.net> wrote in message > > >news:f6138a42-e150-411c-9bed-3f510209de99(a)e21g2000vbl.googlegroups.com... > > | On 21 May, 12:01, va...(a)icmf.inf.cu wrote: > > | > On 20 mayo, 21:42, "Inertial" <relativ...(a)rest.com> > > wrote:><va...(a)icmf.inf.cu> wrote in message > > > | > > > | > > > >news:c13b9123-0513-4072-8dc5-54557b8cfaf5(a)y12g2000vbr.googlegroups.com... > > | > > > | > > > In his first Relativity paper (30June1905), after declaring the > > ether > > | > > > superfluous, Einstein considers a material point at rest. He > > uses > > a > > | > > > system of Cartesian coordinates in which the equations of > > Newtonian > > | > > > mechanics and Euclidean geometry hold good. If the massive body > > is > > | > > > alone (and then without a Newtonian gravitational force acting > > on > > it), > > | > > > it must remains forever at rest in its own centre of mass > > inertial > > | > > > frame. > > | > > > RVHG (Rafael Valls Hidalgo-Gato) > > | > > > | > > Yeup .. do you think that is a problem? > > | > > > | > Not for me, but maybe for other persons. > > | > In the Newtonian view (with absolute space and time), a single > > | > material point can have any constant velocity v in an infinite > > | > quantity of different inertial frames. > > | > > | > In the 1905 Einsteinian view (without absolute space and time), the > > | > same single material point can have only the constant velocity v=0 > > in > > | > a unique inertial frame. > > | > Are we in agreement about that? > > | > > | You've forgotten that inertial frames can be rotated wrt with one > > | another with v = 0 for the material point. > > | > > You've forgotten (or more likely never knew) that Einstein didn't have > > anything to do with Newton's inertial frames and are irrelevant to SR. > > Einstein defines a frame of reference where the laws of > electrodynamics and mechanics holds good. > =============================================== > The laws of electrodynamics and mechanics hold good in all > frames of reference, you just don't know what they are. > http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/gifs/coriolis.mov The Coriolis force is fictitous and not physical. =================================== Who mentioned any force? Certainly not I. Androcles' first law of rotating frames of reference: In a rotating frame of reference every body perseveres in its state of circular motion, or of uniform motion in a perfect circle, unless it is compelled to change that state by forces impressed thereon. The laws of electrodynamics in rotating frames of reference apply to electric motors and generators, look up Fleming's left hand rule. In the frame of reference of the overhead camera the ball follows a straight line. In the frame of reference of the carousel camera the ball follows a circle. No forces involved, fictitious or otherwise. There is only one ball, but two frames of reference. The laws of electrodynamics and mechanics hold good in all frames of reference, *you* just don't know what those laws are and the pathetic ranting dork Einstein hasn't told you, he didn't know either. You obviously don't know any physics, all you know is SR. SR is fictitious and not physical.
From: valls on 24 May 2010 06:47 On 21 mayo, 04:35, harald <h...(a)swissonline.ch> wrote: > On May 21, 1:39 am, va...(a)icmf.inf.cu wrote: > > > > > > > On 20 mayo, 16:43, harald <h...(a)swissonline.ch> wrote: > > > > On May 20, 4:28 pm, va...(a)icmf.inf.cu wrote: > > > > > On 20 mayo, 08:50, harald <h...(a)swissonline.ch> wrote:> On May 20, 3:19 pm, va...(a)icmf.inf.cu wrote: > > > > > > > In his first Relativity paper (30June1905), after declaring the ether > > > > > > superfluous, Einstein considers a material point at rest. He uses a > > > > > > system of Cartesian coordinates in which the equations of Newtonian > > > > > > mechanics and Euclidean geometry hold good. If the massive body is > > > > > > alone (and then without a Newtonian gravitational force acting on it), > > > > > > it must remains forever at rest in its own centre of mass inertial > > > > > > frame. > > > > > > RVHG (Rafael Valls Hidalgo-Gato) > > > > > > If it were alone, yes. But then a theory about relative motion of > > > > > reference systems would certainly be superfluous. ;-) > > > > > But who says that the material point must be always alone? Consider > > > > the Solar System centre of mass inertial reference frame (SS) and the > > > > GPS ECI one. The last can be modelled as a material point that is not > > > > alone (is part of the SS one). As a huge experimental evidence put out > > > > of any doubt, you can model the SS as a single material point at rest, > > > > describing later the Earth (ECI) movement in the SS without any > > > > problem at all. In a similar way, all GPS satellite movements > > > > (including the ground clock ones) can be described in an ECI modelled > > > > as a single material point at rest. > > > > Good / so now you do consider a not so alone particle, and even not a > > > point if you want to establish time measurements at different places. > > > The use of a material point to model part of our Universe as a unique > > entity is inherent to Newtonian mechanics since its beginning. You > > cant formulate any mechanical law (included the universal gravitation > > one) without modelling first all bodies as material points. > > Of course we can - it's just mathematically very handy to simplify > them as points, as far as allowable. > > > The 1684 > > Principia was published only after Newton could prove that an Earth > > modelled by a material point in its centre of mass provokes the same > > action as the real Earth on bodies at its surface and more far away. > > My alone material point at rest can be up to the whole Universe (if it > > can be proved composed by a finite quantity of bodies). > > Ok - that means that your definition of "point" is at odds with mine. > Yours isn't "sharp" in any way > -http://dictionary.reference.com/browse/point > I don´t think we have any disagreement at all about the material point concept. I am taking for granted that we share the same understanding about what it is, the pretty same concept managed by Newton and 1905 Einstein. > > With Einsteins definition of time, you can synchronize a clock at ANY > > point of the space corresponding to ANY centre of mass inertial frame. > > I dont understand the meaning of your even not a point. Please, > > clear me that in your next post. > > If you want to set up a Newtonian coordinate system, you need to > define at least *two* points; a single coordinate cannot be used to > establish time measurements at different places, let alone make a > space-time diagram. > The order in the dependences is important here. Starting with any body set (in which each body is modelled by a material point) you can determine the corresponding unique centre of mass, and that body set can be modelled by a unique material point positioned in that centre with a mass that is the adding of all component body masses. But starting only with that unique material point, you can´t determine the body set (there exist infinite possible ones, each one with a different space and a different time). Then, the starting body set must have at least two bodies (the material points modelling them are surely the at least two points you are referring). The very important thing here is to realize that once 1905 Einstein put out the ether (and with it Newtons absolute space and time), all the derived inertial frames moving with all possible uniform velocities v with respect to any real inertial frame are also put out. They all correspond to the empty body set with zero material points, and as you say, at least two of them are needed to define a time (an also a space) in the 1905 Einsteins sense. > > > > Do you consider yet superfluous a theory about relative motion of > > > > reference systems? Note that the moving system must be always part > > > > of the stationary system, and a stationary system moving with > > > > respect to a moving system at rest is nothing more that a huge > > > > absurd (do you remember Ptolomys Sun going around the Earth?). > > > > Following your arguments elsewhere, here we dont care about what you > > > think. Einsteins thoery does not prefer one inertial system over the > > > other, it is not supporting your theory. > > > Long before Einstein, to any body set correspond a unique centre of > > mass inertial frame. You never have more than one CM inertial frame to > > describe the same body set (the holding of Newtons laws is the > > cause). > > Newton's first law and the related Newtonian coordinate systems do not > depend on " unique centre of mass"... > In the Newtonian view (with absolute space and time as fundamental concepts), an infinity quantity of inertial frames corresponding to the empty body set (with zero material points) are included. These are the frames not depending on a unique centre of mass that you are referring. As we need at least two points (as you say) to have defined a time in the 1905 Einsteins sense, they are all excluded from that view. In the Newtonian view, all centre of mass inertial frames are considered apparent and false, being real and true only the one with absolute space and time. In the 1905 Einsteins view, the centre of mass inertial frames corresponding to body sets with at least two material points are all considered real and true and the unique existing ones. > > By the way, we are considering here only 1905 Relativity (and > > I was born long after that epoch). 1905 Einstein can support only 1905 > > Relativity. > > Exactly, that is what I referred to. His purpose was to show how: > > "the same laws of electrodynamics and optics will be valid for all > frames of reference for which the equations of mechanics hold good" > > with the clarification: > > "In order to render our presentation more precise and to distinguish > this system of co-ordinates *verbally* from others which will be > introduced hereafter, we call it the ``stationary system.'' " > And the stationary system is for 1905 Einstein a one in which the equations of Newtonian mechanics hold good and a time can be determined applying his clock synchronization procedure, i.e., according to our previous considerations, a centre of mass inertial frame corresponding to a body set with at least two bodies. > That is at odds with your statement that: > > > > > "the moving system must be always part > > > > of the stationary system, and a stationary system moving with > > > > respect to a moving system at rest is nothing more that a huge > > > > absurd [..]. > What contradiction do you find between that statement and 1905 Einstein? I can support all what I say using only the 1905 text. As absolute space and time are out, the space and time used to describe the movement of any thing must be only the space and time corresponding to some CM inertial frame, and the moving entity can be only one body belonging to the body set corresponding to that frame. As the motion of the CM is totally independent on all the material points of the body set (a fact derived from Newtons laws), to say that the stationary system (modelled by a material point in its CM) is moving with respect to one of the component material points, is nothing more than a huge absurd (referring to the real example in the 30June1905 text, the clock at rest in the pole cant be moving with respect to the moving clock at the equator). > Regards, > Harald RVHG (Rafael Valls Hidalgo-Gato)
From: valls on 24 May 2010 06:57 On 21 mayo, 07:15, "Greg Neill" <gneil...(a)MOVEsympatico.ca> wrote: > va...(a)icmf.inf.cu wrote: > > On 20 mayo, 13:09, PD <thedraperfam...(a)gmail.com> wrote: > >> On May 20, 8:19 am, va...(a)icmf.inf.cu wrote: > > >>> In his first Relativity paper (30June1905), after declaring the ether > >>> superfluous, Einstein considers a material point at rest. He uses a > >>> system of Cartesian coordinates in which the equations of Newtonian > >>> mechanics and Euclidean geometry hold good. If the massive body is > >>> alone (and then without a Newtonian gravitational force acting on it), > >>> it must remains forever at rest in its own centre of mass inertial > >>> frame. > > >> Yes. So? > > >> Every object lives in an infinite multitude of frames. The ones that > >> have constant velocity with the frame you just described, plus this > >> frame itself, constitutes the set of inertial frames. > > > If we apply that to the single material point case, the result is an > > infinite number of inertial frames where the single material point can > > be moving with any velocity v. Once the ether is put out by 1905 > > Einstein (and with it the Newtonian absolute space and time), can you > > explain to me with respect to what a single material point can have > > then a velocity different from zero? > > A single material point can have any desired velocity > simply by choosing a suitable frame of reference (for > the observer) that is not identical to the frame of > reference in which the particle is at rest. > Your answer is totally invalid in 1905 Relativity (even if valid in today Special Relativity). See the following references to the 30Jun1905 text. Almost at the end of the Introduction: R1. [The theory to be developed is based like all electrodynamics on the kinematics of the rigid body, since the assertions of any such theory have to do with the relationships between rigid bodies (system of co-ordinates), clocks, and electromagnetic processes.] At the beginning of paragraph 3: R2. [Let us in stationary space take two systems of co-ordinates, i.e. two systems, each of three rigid material lines, perpendicular to one another, and issuing from a point.] In R1 a system of co-ordinates is identified with a rigid body, and in R2 (more detailed) with a system of tree rigid material lines. Even a single material point must have some mass, imagine tree material lines. Then, a single material point can be (in 1905 Relativity) only at rest, because we have nothing more material for that material point to be moving with respect to it. > A frame of reference is not a material thing, it is a > coordinate system construction. You have proposed a > thought experiment where a universe contains but one > single particle and a (presumably) discorporate, > purely theoretical observer. This "observer" can be > in any frame of reference that you choose. > I am not making a gedanken. To model part of our real Universe as a single material point at rest is a completely valid procedure supported with real experimental evidence. The Earth in the GPS ECI is a good example; the Solar System is another one. You are the one making a gedanken with a violation of the assumed premise of a unique material point when considering another different inertial frame without having any more material to establish it. > >> The question of interest is what is the relationship between various > >> physical properties, as measured in different inertial frames? > > Yes, but before addressing that we must put clear which are the > > inertial frames involved. > > All of them. They are purely theoretical so they are > cheap and easy to deploy. Pin one to your "material > point" and another to your observer (even if he's > purely theoretical in your gedanken universe). You are evidently referring to the imaginary infinite inertial frames moving with all possible uniform velocity v with respect to some real inertial frame. Sorry, in 1905 Relativity we have only real inertial frames, each one with a different material support. RVHG (Rafael Valls Hidalgo-Gato)
From: valls on 24 May 2010 07:13 On 21 mayo, 10:22, PD <thedraperfam...(a)gmail.com> wrote: > On May 21, 6:27 am, va...(a)icmf.inf.cu wrote: > > > > > > > On 20 mayo, 13:09, PD <thedraperfam...(a)gmail.com> wrote: > > > > On May 20, 8:19 am, va...(a)icmf.inf.cu wrote: > > > > > In his first Relativity paper (30June1905), after declaring the ether > > > > superfluous, Einstein considers a material point at rest. He uses a > > > > system of Cartesian coordinates in which the equations of Newtonian > > > > mechanics and Euclidean geometry hold good. If the massive body is > > > > alone (and then without a Newtonian gravitational force acting on it), > > > > it must remains forever at rest in its own centre of mass inertial > > > > frame. > > > > Yes. So? > > > > Every object lives in an infinite multitude of frames. The ones that > > > have constant velocity with the frame you just described, plus this > > > frame itself, constitutes the set of inertial frames. > > > If we apply that to the single material point case, the result is an > > infinite number of inertial frames where the single material point can > > be moving with any velocity v. > > Any velocity of magnitude less than c, yes. So? > > > Once the ether is put out by 1905 > > Einstein (and with it the Newtonian absolute space and time), can you > > explain to me with respect to what a single material point can have > > then a velocity different from zero? > > A reference frame does not require a material "anchor" object, for > which that anchor object is at rest in that frame. > What do you say is totally valid in today Special Relativity, but not in 1905 Relativity. See the following references to the 30Jun1905 text. Almost at the end of the Introduction: R1. [The theory to be developed is based like all electrodynamics on the kinematics of the rigid body, since the assertions of any such theory have to do with the relationships between rigid bodies (system of co-ordinates), clocks, and electromagnetic processes.] At the beginning of paragraph 3: R2. [Let us in stationary space take two systems of co-ordinates, i.e. two systems, each of three rigid material lines, perpendicular to one another, and issuing from a point.] In R1 a system of co-ordinates is identified with a rigid body, and in R2 (more detailed) with a system of tree rigid material lines. Even a single material point must have some mass, imagine tree material lines. Do you continue thinking that in 1905 Relativity a reference frame does not require something material to establish the rest? > If that were the case, then for two reference frames to even exist, > you'd need two objects. For three, you'd need three objects. > Exactly. See in the previous reference R2 a different material object for each one of the two different reference systems introduced. > This however, is not the case. A reference frame has a perfectly well- > defined meaning with or without a material anchor in it. > A valid assertion in today Special Relativity, but a totally invalid one in 1905 Relativity. In this thread we are addressing only 1905 Relativity (see the title). > Thus, a single material object lives in not one, but an infinitude of > reference frames. In one of those inertial reference frames, the > object happens to be at rest. > The Earth modelled as a single material point in its centre of mass is at rest in the GPS ECI System, moving in a monthly almost circular trajectory around the centre of mass of the Earth-Moon System (CMEM), and that CMEM is moving in a yearly trajectory around the centre of mass of the Solar System (CMSS). The CMSS has a velocity of about 250Km/s in the Galaxy System, etc. Are these systems the ones you have in mind when talking about infinite ones? Do you consider that the different states of motion of the Earth in those different systems are totally equivalent ones? Or maybe some one is more valid that some other? > > > > The question of interest is what is the relationship between various > > > physical properties, as measured in different inertial frames? > > > Yes, but before addressing that we must put clear which are the > > inertial frames involved. > > > RVHG (Rafael Valls Hidalgo-Gato) RVHG (Rafael Valls Hidalgo-Gato)
From: PD on 24 May 2010 08:27
On May 24, 6:13 am, va...(a)icmf.inf.cu wrote: > On 21 mayo, 10:22, PD <thedraperfam...(a)gmail.com> wrote: > > > On May 21, 6:27 am, va...(a)icmf.inf.cu wrote: > > > > On 20 mayo, 13:09, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On May 20, 8:19 am, va...(a)icmf.inf.cu wrote: > > > > > > In his first Relativity paper (30June1905), after declaring the ether > > > > > superfluous, Einstein considers a material point at rest. He uses a > > > > > system of Cartesian coordinates in which the equations of Newtonian > > > > > mechanics and Euclidean geometry hold good. If the massive body is > > > > > alone (and then without a Newtonian gravitational force acting on it), > > > > > it must remains forever at rest in its own centre of mass inertial > > > > > frame. > > > > > Yes. So? > > > > > Every object lives in an infinite multitude of frames. The ones that > > > > have constant velocity with the frame you just described, plus this > > > > frame itself, constitutes the set of inertial frames. > > > > If we apply that to the single material point case, the result is an > > > infinite number of inertial frames where the single material point can > > > be moving with any velocity v. > > > Any velocity of magnitude less than c, yes. So? > > > > Once the ether is put out by 1905 > > > Einstein (and with it the Newtonian absolute space and time), can you > > > explain to me with respect to what a single material point can have > > > then a velocity different from zero? > > > A reference frame does not require a material "anchor" object, for > > which that anchor object is at rest in that frame. > > What do you say is totally valid in today Special Relativity, but not > in 1905 Relativity. See the following references to the 30Jun1905 > text. > Almost at the end of the Introduction: > R1. [The theory to be developed is based like all electrodynamics on > the kinematics of the rigid body, since the assertions of any such > theory have to do with the relationships between rigid bodies (system > of co-ordinates), clocks, and electromagnetic processes.] > At the beginning of paragraph 3: > R2. [Let us in stationary space take two systems of co-ordinates, > i.e. two systems, each of three rigid material lines, perpendicular to > one another, and issuing from a point.] > In R1 a system of co-ordinates is identified with a rigid body, and in > R2 (more detailed) with a system of tree rigid material lines. Even a > single material point must have some mass, imagine tree material > lines. Do you continue thinking that in 1905 Relativity a reference > frame does not require something material to establish the rest? Yes. Just because Einstein uses a material framework to *explain* his position does not mean that it is essential to the conceptual framework. The idea of reference frames without material anchors preceded Einstein by at least a century. > > > If that were the case, then for two reference frames to even exist, > > you'd need two objects. For three, you'd need three objects. > > Exactly. See in the previous reference R2 a different material object > for each one of the two different reference systems introduced.> This however, is not the case. A reference frame has a perfectly well- > > defined meaning with or without a material anchor in it. > > A valid assertion in today Special Relativity, but a totally invalid > one in 1905 Relativity. In this thread we are addressing only 1905 > Relativity (see the title). This, in my opinion, is a boondoggle. I don't see the point of it at all. Relativity is relativity. It is not a *creation*, it is a discovery. When the first sailors navigated to the New World, they drew maps that represented their view of their discovery. Of course, those maps did not at all accurately represent the shape of the Americas. It does absolutely no good to take one of those maps and say, "But this is the America of 1500." It is not. The shape of the continent has not substantively changed since 1500. The America of 1500 is the same as the America of 2010. It's just that how people have described it is a little different from 1500 to 2010. > > > Thus, a single material object lives in not one, but an infinitude of > > reference frames. In one of those inertial reference frames, the > > object happens to be at rest. > > The Earth modelled as a single material point in its centre of mass is > at rest in the GPS ECI System, moving in a monthly almost circular > trajectory around the centre of mass of the Earth-Moon System (CMEM), > and that CMEM is moving in a yearly trajectory around the centre of > mass of the Solar System (CMSS). The CMSS has a velocity of about > 250Km/s in the Galaxy System, etc. Are these systems the ones you have > in mind when talking about infinite ones? No, because they aren't inertial, are they? > Do you consider that the > different states of motion of the Earth in those different systems are > totally equivalent ones? Or maybe some one is more valid that some > other? > > > > > > The question of interest is what is the relationship between various > > > > physical properties, as measured in different inertial frames? > > > > Yes, but before addressing that we must put clear which are the > > > inertial frames involved. > > > > RVHG (Rafael Valls Hidalgo-Gato) > > RVHG (Rafael Valls Hidalgo-Gato) |