The moving system is not an inertial frame in 1905 Relativity
in [Relativity]
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From: valls on 5 Jul 2010 10:40 On 2 jul, 09:14, PD <thedraperfam...(a)gmail.com> wrote: > On Jul 2, 6:07 am, va...(a)icmf.inf.cu wrote: > > > > > > > On 1 jul, 10:25, PD <thedraperfam...(a)gmail.com> wrote: > > > > 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. > > > If you have TWO inertial frames (real massive ones, not the imaginary > > massless ones rejected by 1905 Einstein), then they can't be never > > moving at a uniform velocity one with respect to the other (at least > > some gravitational attraction must be present always). > > Don't be ridulous. Your coffee cup and the table is sitting on have a > uniform velocity with respect to each other (zero), even though there > is a gravitational attraction. An elevator and the 3rd floor move at > uniform velocity with respect to each other (nonzero), even though > there is a gravitational attraction present. Just because there is a > gravitational attraction present doesn't remove the presence of OTHER > forces which can put two objects in equilibrium, either static or > nonstatic. > I am not rejecting at all Nature forces of any kind. The coffee cup and the table you refer are both moving with a non-zero gravitational centripetal acceleration in a circular path in the GPS ECI, because I dont stay in a pole (as the clock at the equator in the example at the end of paragraph 4 in the 30Jun1905 Einsteins paper). They cant be considered then inertial frames. Yes, they are two entities with a uniform zero relative velocity, but they are NOT two inertial frames. The same remark about your elevator and floor. Only in the Newtonian view you can derive a different inertial frame from another referring a uniform velocity between them (the way the infinite imaginary inertial frames moving with all possible uniform velocities with respect to the imaginary absolute one are put in existence). In 1905 Relativity, even if you can obtain two entities moving with a relative uniform velocity compatible with Nature laws, they cant be inertial frames, because even being them the unique entities considered by you, the centre of mass inertial system of all the bodies involved continue being the UNIQUE possible inertial frame. I accept that my previous explanation referring only to a gravitational interaction between the two supposed inertial frames is not a sufficient one. You were right rejecting it. > If what you said were true, then Newton's first law would be USELESS, > and it is not. > That the state of motion of any body without interaction with its exterior remains constant, continue being valid in 1905 Relativity. It allows us to understand why the centre of mass of any inertial system must be always at rest if you want to describe in it the movement of any body belonging to its body set. By the way, these are the UNIQUE bodies whose movements can be described in that inertial frame. > > As a result, > > you must consider the centre of mass inertial frame corresponding to > > all the bodies involved. For ANY body set, you have always a UNIQUE > > centre of mass inertial frame. > > That is true, you do have a unique center of mass frame. However, that > is not the only inertial reference frame in that system. It is one of > many. > The inertial reference frame and the system is one and the same thing. Starting with ANY body set, you obtain a UNIQUE inertial frame, the centre of mass one corresponding to that body set. Please, explain to me (with a real example, if possible) which are these many inertial reference frames that you are referring. And remember that we are addressing 1905 Relativity (without the imaginary absolute inertial frame and the also imaginary derived ones moving with all possible uniform velocities with respect to it). > > I accepted the definition of inertial frame that you refer. Physics > > laws must be always the same in all inertial frames. But I don't > > accept that and entity moving at a uniform velocity with respect to > > some inertial frame is also an inertial frame (at least not a real > > existing one). > > Then you need to demonstrate to yourself that, in a reference frame > that is moving at uniform velocity with respect to the center of mass > of a system of bodies, the laws of physics are still the same. Galileo > saw that in the early 1600's, but I see you haven't figured that out > yet. When you see this is true, then by definition this frame is an > inertial reference frame. > Remember the Galileo ship moving with a uniform velocity. In the INTERIOR of the ship all things happens in the same way not depending on the uniform velocity that the ship as a whole has with respect to an EXTERNAL entity. But all the windows must remain closed. That is a way to say that outside it is nothing. Let us take a more modern example to make more clear what I am trying to say. Consider the ECI, our Earth rotating (the stationary system in the referred example in the 1905 text). It is a centre of mass inertial frame. Like in the Galileos ship, you must consider existing only the bodies in its INTERIOR, you cant use the ECI to describe the movement of any body in its EXTERIOR (even the Moon, not to say the Sun!). Even supposing an Earth with a uniform motion in the Solar System centre of mass inertial frame (trying to fulfil the requirements for your supposed inertial frame moving with a uniform velocity with respect to a centre of mass inertial frame) , you cant describe the Suns movement in the ECI (the same with ANY other body external to the Earth). Yes, the laws of physics are the same in the ECI INTERIOR and in the Solar System INTERIOR (in the INTERIOR of any centre of mass inertial system, considering INTERIOR the set of all the bodies involved). But I am pretty sure that when you refer to an inertial frame moving with a uniform velocity with respect to some centre of mass inertial system, what you have in mind is to use that uniform moving inertial system to describe the movements of bodies in its EXTERIOR. That is totally impossible. In the EXTERIOR of any moving entity (with uniform velocity or not), it cant be never an inertial system. And a moving system can be considered an inertial frame in its INTERIOR, only if the external world provokes a sufficiently same ACCELERATION in all its internal bodies (as is the case for the ECI and the Solar System). RVHG (Rafael Valls Hidalgo-Gato)
From: valls on 5 Jul 2010 11:29 On 2 jul, 06:29, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > va...(a)icmf.inf.cu says... > > > > >On 1 jul, 20:44, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > >> You are confused. In the respect of what is involved in an inertial > >> frame, there is no difference between Special Relativity and Newtonian > >> physics. In both cases, an inertial frame is a set of comoving unaccelerated > >> comoving points such that any of the points has zero relative velocity.. > >I am considering in this thread only 1905 Relativity. > > You would be much better off trying to understand relativity, instead of > treating it like a sacred text. Don't use Einstein's paper, use a more > modern treatment. > I have my reasons to select the topic of this thread, 1905 Relativity (1905R). You can know about them seeing some other threads that I had opened with the same basic topic. From 1905R I had derived already some things, like the behaviour of atomic clocks in a gravitational field and other effects only explained today using General Relativity. No text is for me sacred, we must evaluate them by they own merits, taking always into account that any concept developed in its future must be always out of the interpretation we do of the text. As an example, the today concept of rest mass cant be used to interpret the 27Sep1905 Einsteins paper where the mass-energy relationship is showed. The result is that Potential Energy is present in 1905R, with rest mass measuring it (without any arbitrary additive constant). The consequences can be many. > The rotating Earth is *not* an inertial frame for the purposes of > Special Relativity. > I dont care at all Special Relativity, introduced by 1916 Einstein. The rotating Earth (a centre of mass inertial frame) is the principal example we can find in 1905R, being here the stationary system, the same one denoted today GPS ECI, with a huge experimental evidence supporting 1905R. The moving system is a clock at the equator, which is very clearly not an inertial frame. > -- > Daryl McCullough > Ithaca, NY RVHG (Rafael Valls Hidalgo-Gato)
From: Daryl McCullough on 5 Jul 2010 12:11 valls(a)icmf.inf.cu says... > >On 2 jul, 06:29, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: >> va...(a)icmf.inf.cu says... >> The rotating Earth is *not* an inertial frame for the purposes of >> Special Relativity. >> >I don't care at all Special Relativity, introduced by 1916 Einstein. You mean General Relativity. Special Relativity was 1905. >The rotating Earth (a centre of mass inertial frame) is the principal >example we can find in 1905R, being here the stationary system, the >same one denoted today GPS ECI, with a huge experimental evidence >supporting 1905R. The moving system is a clock at the equator, which >is very clearly not an inertial frame. That's not correct. Depending on exactly what you are trying to compute, you can sometimes treat the Earth as *approximately* an inertial frame, but for precise measurements, it is not an inertial frame. -- Daryl McCullough Ithaca, NY
From: Tom Roberts on 5 Jul 2010 13:11 valls(a)icmf.inf.cu wrote: > If you have TWO inertial frames (real massive ones, not the imaginary > massless ones rejected by 1905 Einstein), then they can't be never > moving at a uniform velocity one with respect to the other (at least > some gravitational attraction must be present always). But in practice, such gravitational attraction s can be completely negligible. Such as for particle interactions in accelerators here on earth. Moreover, in an analysis using SR one must IGNORE gravitation. As Einstein showed during 1909-1915, there is no simple generalization of gravity to SR, one needs full GR. Physics is about modeling the world. It often makes sense to ignore negligible interactions, even though we know they are present. So in particle physics we ignore the gravity of the earth, even though we know it is present -- it is billions of times smaller than our measurement resolutions, so the complexity of including it would be completely wasted effort. Tom Roberts
From: whoever on 5 Jul 2010 19:49
wrote in message news:b311b182-91d7-466a-bd07-96f70e2173d6(a)j4g2000yqh.googlegroups.com... >I have my reasons to select the topic of this thread, 1905 Relativity >(1905R). You can know about them seeing some other threads that I had >opened with the same basic topic. From 1905R I had derived already >some things, like the behaviour of atomic clocks in a gravitational >field That is not part of 1905R .. its GR > and other effects only explained today using General Relativity. They are no explained at all in 1905R. You seem very confused >No text is for me sacred, we must evaluate them by they own merits, No text is understood, more likely > taking always into account that any concept developed in its future >must be always out of the interpretation we do of the text. As an >example, the today concept of rest mass can�t be used to interpret the >27Sep1905 Einstein�s paper where the mass-energy relationship is >showed. The result is that Potential Energy is present in 1905R, with >rest mass measuring it (without any arbitrary additive constant). The >consequences can be many. >> The rotating Earth is *not* an inertial frame for the purposes of >> Special Relativity. >> >I don�t care at all Special Relativity, introduced by 1916 Einstein. No .. in 1905 >The rotating Earth (a centre of mass inertial frame) is the principal >example we can find in 1905R, 1905R (as the first exposition of SR) does not deal with gravity > being here the stationary system, the >same one denoted today GPS ECI, with a huge experimental evidence >supporting 1905R. 1905R does not predict gravitational time dilation. So that claim is wrong > The moving system is a clock at the equator, which >is very clearly not an inertial frame. And so not covered by 1905R --- news://freenews.netfront.net/ - complaints: news(a)netfront.net --- |