The moving system is not an inertial frame in 1905 Relativity
in [Relativity]
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From: Daryl McCullough on 1 Jul 2010 07:58 valls(a)icmf.inf.cu says... >You forget that the topic in this thread is 1905 Relativity, where an >inertial frame, denoted by 1905 Einstein stationary system, is related >with mass without any doubt at all. To help you the understanding of >it, I will put here some text from the 30Jun1905 Einstein's paper >(between [ ]): >[Let us take a system of co-ordinates in which the equation of >Newtonian mechanics hold good.]. A direct identification between >inertial system with massive system of co-ordinates. I agree that the first sentence in [] is from Einstein, but the second isn't. He doesn't define a "massive system of co-ordinates" and he *certainly* doesn't, anywhere in the paper say that the only inertial frame is that of the center of mass. >At the beginning of paragraph 3: [Let us in "stationary space" take >two system of co-ordinates, i.e. two systems, each of three rigid >material lines, perpendicular to one another, and issuing from a >point.]. A single material point is already a massive entity, and we >have here RIGID MATERIAL LINES associated with the inertial frames. I >will suppose this is already sufficient for you to understand that to >talk about a non-massive inertial frame in 1905 Relativity is a >complete absurd. You are confused. The paragraph does not mention mass at all. The point of talking about "rigid material lines" is about *setting up* a coordinate system. To set up a rectangular coordinate system, you need three things: (1) Clocks, (2) rulers, and (3) a standard for 3 orthogonal spatial directions (which might be three orthogonal rods stuck together at a point). The clocks, rulers and orthogonal standard should be thought of as material objects in the sense that they have a definite location, orientation and velocity at each moment. That's the only thing that is important about them. Certainly their mass doesn't come into play, and it is certainly irrelevant for Special Relativity that they be associated with a center of mass. If there are other huge masses nearby, that is only relevant to the extent that they would force the consideration of gravity, which is not covered by Special Relativity. -- Daryl McCullough Ithaca, NY
From: Daryl McCullough on 1 Jul 2010 08:41 In article <7ecc2746-829e-4e69-81d4-45d45530ecd2(a)e5g2000yqn.googlegroups.com>, valls(a)icmf.inf.cu says... I have to give you credit---this is a brand *NEW* misunderstanding of relativity. The usual misunderstandings that are the basis for discussion in this newsgroup date back to Herbert Dingle back in the 1950s, more than 50 years ago. Dingle would love this newsgroup. Too bad there was no internet back then. -- Daryl McCullough Ithaca, NY
From: artful on 1 Jul 2010 09:21 On Jul 1, 8:42 pm, va...(a)icmf.inf.cu wrote: > On 30 jun, 19:22, "whoever" <whoe...(a)whereever.com> wrote: > > > > > >wrote in message > > >news:cf9a3f56-d5ca-4a3e-8df9-29d3d626153c(a)5g2000yqz.googlegroups.com.... > > > >On 30 jun, 15:13, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > > >> va...(a)icmf.inf.cu says... > > > >> >In a recent thread we established that > > >> > Centre of mass inertial frames are the unique ones in 1905 > > >> >Relativity > > > >> There is nothing in the development of relativity that in any > > >> way depends on a frame being defined by a center of mass. That's > > >> completely barking up the wrong tree. > > > >> -- > > >> Daryl McCullough > > >> Ithaca, NY > > > >I will answer you with the same initial post of the referred thread: > > > Repeating nonsense does not make it true > > > > [Let be any body set with a material point modelling each one. > > > OK .. so you start off with an ungrammatical sentence which makes no sense. > > > Try again > > A body modelled by a material point is a very basic Newtonian concept. > Without it, the Newtonian mechanics laws have no sense at all. The > position of a body in some space at the corresponding instant of some > time, is the position of the material point modelling the body. Any > force acting in a body is a force acting in a straight line crossing > the material point modelling the body. The distance between two bodies > (to appy the gravitation law) is the distance between the material > points modelling the two bodies. You need more? No .. know all that .. point particles are pretty basic. At least you've said something that makes grammatical sense >Try again. I don't need to.
From: PD on 1 Jul 2010 11:25 On Jun 30, 3:31 pm, va...(a)icmf.inf.cu wrote: > On 30 jun, 15:13, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > > > va...(a)icmf.inf.cu says... > > > >In a recent thread we established that > > > Centre of mass inertial frames are the unique ones in 1905 > > >Relativity > > > There is nothing in the development of relativity that in any > > way depends on a frame being defined by a center of mass. That's > > completely barking up the wrong tree. > > > -- > > Daryl McCullough > > Ithaca, NY > > I will answer you with the same initial post of the referred thread: > [Let be any body set with a material point modelling each one. If we > want to describe the movements of the bodies in an inertial frame, we > have a unique alternative: to use the centre of mass inertial frame > corresponding to that body set. Once the Newtons absolute frame is > rejected by 1905 Einstein (and then rejected also all the others > moving with any uniform velocity with respect to it), remain only the > bodies themselves to determine inertial frames.] > Explain to us how can you determine an inertial frame once the > absolute Newtonian one is rejected by 1905 Einstein(and with it all > the others imaginary derived ones with all possible uniform velocities > with respect to it). > > RVHG (Rafael Valls Hidalgo-Gato) Inertial frames are *defined* by the fact that the laws of dynamics retain their form in such frames. The center of mass frame of a system of mutually interacting bodies is such an inertial frame (provided that there is no measurably significant interaction with bodies external to this system), but it is also true that ANY OTHER FRAME moving at constant velocity with respect to the center of mass frame also satisfies this requirement. This can be easily verified in classical mechanics on a billiard table, where we are considering only the interactions between the billiard balls during a period where there is no collision with the rails, and ignoring any momentum transfer to the table due to friction between ball and felt. The frame in which the center of mass is stationary is a fine inertial frame in this case, but so is any other frame moving at constant velocity with respect to the center of mass. PD
From: valls on 1 Jul 2010 12:06
On 1 jul, 08:21, artful <artful...(a)hotmail.com> wrote: > On Jul 1, 8:42 pm, va...(a)icmf.inf.cu wrote: > > > > > > > On 30 jun, 19:22, "whoever" <whoe...(a)whereever.com> wrote: > > > > >wrote in message > > > >news:cf9a3f56-d5ca-4a3e-8df9-29d3d626153c(a)5g2000yqz.googlegroups.com.... > > > > >On 30 jun, 15:13, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > > > >> va...(a)icmf.inf.cu says... > > > > >> >In a recent thread we established that > > > >> > Centre of mass inertial frames are the unique ones in 1905 > > > >> >Relativity > > > > >> There is nothing in the development of relativity that in any > > > >> way depends on a frame being defined by a center of mass. That's > > > >> completely barking up the wrong tree. > > > > >> -- > > > >> Daryl McCullough > > > >> Ithaca, NY > > > > >I will answer you with the same initial post of the referred thread: > > > > Repeating nonsense does not make it true > > > > > [Let be any body set with a material point modelling each one. > > > > OK .. so you start off with an ungrammatical sentence which makes no sense. > > > > Try again > > > A body modelled by a material point is a very basic Newtonian concept. > > Without it, the Newtonian mechanics laws have no sense at all. The > > position of a body in some space at the corresponding instant of some > > time, is the position of the material point modelling the body. Any > > force acting in a body is a force acting in a straight line crossing > > the material point modelling the body. The distance between two bodies > > (to appy the gravitation law) is the distance between the material > > points modelling the two bodies. You need more? > > No .. know all that .. point particles are pretty basic. At least > you've > said something that makes grammatical sense > Don't confuse point particle with material point. Our whole Solar System is modelled by a material point to describe its movement in the Galaxy. The Earth-Moon system is modelled by a material point to describe the ecliptic. RVHG (Rafael Valls Hidalgo-Gato) |