According to 1905 Relativity, a single material point must be always at rest
in [Relativity]
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From: Darwin123 on 29 May 2010 12:07 On May 28, 7:29 pm, va...(a)icmf.inf.cu wrote: > On 27 mayo, 12:48, PD <thedraperfam...(a)gmail.com> wrote: > > > On May 26, 3:49 pm, va...(a)icmf.inf.cu wrote: > > > > On 25 mayo, 10:46, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On May 25, 10:19 am, va...(a)icmf.inf.cu wrote: > > > > > > On 24 mayo, 07:27, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > 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: > > You are accusing then 1684 Newton to make a rather empty statement > (without any valid argument to support it). The concept of the non- > existence of a privileged frame is developed precisely by 1905 > Einstein, and the translation of something to the past of its > developing epoch is the more dangerous mistake that can be done when > analysing an old text (but unfortunately a very common one, because it > is not an easy task at all to consider out of our mind what it is > already there when reading the old text, and the greater the > knowledge, the greater the possibility to fall in mistake). > I am not accusing Newton of making a rather empty statement. Newton's "absolute frame" is not privileged any more than Einstein's "stationary frame". In both cases, one frame is selected where the laws of mechanics (Newton's Principia) are strictly valid. In both cases, there are an infinite number of frames that also satisfy the condition that Principia holds true. However, to first order neither the absolute frame nor the stationary frame are unique in satisfying the rules of Principia. The force laws studied by Newton and his contemporaries are Galilean invariant. I don't know when the concept of Galilean invariance first arose. However, suppose we have a set of measuring instruments that are at rest with respect to the absolute frame. One can construct another set of instruments using a Galilean transformation that also satisfies the condition that Principia holds true. So if Newton had constructed a "primed" frame using Galilean invariants, he could have performed all his calculations from the POV of this primed frame and still gotten equivalent results. However, this was not necessary for the calculations that he demonstrated in Principia. I have no references as to the use of the Galilean transformation before Einstein. I will search for some. Apparently, Newton never describes the Galilean transformation. Even if Newton had thought of the Galilean transformation, they would have been anticlimatic. The main thing he does with Principia is calculate planetary orbits. For calculating planetary orbits, one absolute space was enough. Even if he invented the Galilean transformation, it was tangential to the main points of Principia. Newton was introducing the world to physics. Mathematical embellishments would only have confused the issues at that point. Light does not obey the laws stated in Principia. Certain people on the forum will say that light does somehow obey Principia, but that is not true. We can argue the point experiment by experiment, but in summation the laws of Principia don't apply to light. The laws of optics are not Galilean invariant. Einstein intentionally searched for a transformation that would construct a second frame where both Principia and the Laws of Optics would apply to first order. To satisfy both Principia and the Laws of optics, Einstein developed the Lorentz transformation. Of course, the Lorentz transformation had been developed first by Lorentz. Lorentz developed these equations for a slightly different reasons. Lorentz was seems to have been concerned about a slight inconsistency between Principia and the force laws of electrodynamics. I think that characterizes the difference in approach between Einstein and Lorentz. Einstein was concerned primarily with optics, and Lorentz was concerned with electromagnetic force laws. Einstein got full credit in the public eye for special relativity after he developed general relativity. The argument of "who deserves credit" for special relativity is interesting, but unimportant for the discussion at hand. I will not argue for either, as I am in awe of both of them |:-) The idea of Galilean transformation was already in the air soon after Newton published Principia. What Lorentz and Einstein found was that the Laws of the universe are invariant to a different transformation, which is now called the Lorentz transformation. The invariance of physical law to the Lorentz transformation turns out to have consequences beyond both optics and the electrodynamic force laws. Invariance to the Lorentz transformation apparently extends beyond optics and electrodynamics. The Lorentz invariance even applies to systems where Principia is totally invalid, such as quantum mechanical systems. In any case, the "inertial frame" was fully described without using the exact phrase in Einstein's 1905 paper. He describes a stationary frame, which is fully equivalent to the absolute frame described by Newton. He shows that other frames satisfy the same conditions as the stationary frame. He refers to them as the "primed coordinates," but it is the same concept as inertial frame. Not all frames are inertial frames in the sense that Einstein defined inertial frames. If an external force is applied to the instruments in an inertial frame, the frame will accelerate. Then, the laws of Principia don't apply in this frame. This was as true for the universe described by Newton as it is for the universe as described by Einstein. However, an accelerated frame can approximate an inertial frame given certain conditions. While one can never totally insulate instruments from external forces, there are conditions where these external forces are negligible. Thus, the center of mass of the earth is sufficiently close to being an inertial frame for certain experiments, including the GPS satellites. However, the earth centered system is not an absolute frame. Why should the earth be any more inertial than any other planet or star in the galaxy? I just am picking a small nit. I agree that the frame centered on the center of mass of the earth is a sufficiently close to being an inertial frame for most purposes. The earth centered frame may not be an ideal inertial frame, but it is for the purposes of current technology an inertial frame.
From: Androcles on 29 May 2010 12:25 "Darwin123" <drosen0000(a)yahoo.com> wrote in message news:afde7934-0eab-400e-af8f-ca02b3fe44d3(a)u7g2000vbq.googlegroups.com... On May 28, 7:29 pm, va...(a)icmf.inf.cu wrote: > On 27 mayo, 12:48, PD <thedraperfam...(a)gmail.com> wrote: > > > On May 26, 3:49 pm, va...(a)icmf.inf.cu wrote: > > > > On 25 mayo, 10:46, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On May 25, 10:19 am, va...(a)icmf.inf.cu wrote: > > > > > > On 24 mayo, 07:27, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > 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: > > You are accusing then 1684 Newton to make a rather empty statement > (without any valid argument to support it). The concept of the non- > existence of a privileged frame is developed precisely by 1905 > Einstein, and the translation of something to the past of its > developing epoch is the more dangerous mistake that can be done when > analysing an old text (but unfortunately a very common one, because it > is not an easy task at all to consider out of our mind what it is > already there when reading the old text, and the greater the > knowledge, the greater the possibility to fall in mistake). > I am not accusing Newton of making a rather empty statement. Newton's "absolute frame" is not privileged any more than Einstein's "stationary frame". ================================================== " Hitherto I have laid down the definitions of such words as are less known, and explained the sense in which I would have them to be understood in the following discourse. I do not define time, space, place and motion, as being well known to all. Only I must observe, that the vulgar conceive those quantities under no other notions but from the relation they bear to sensible objects. And thence arise certain prejudices, for the removing of which, it will be convenient to distinguish them into absolute and relative, true and apparent, mathematical and common. Absolute space, in its own nature, without regard to anything external, remains always similar and immovable. Relative space is some movable dimension or measure of the absolute spaces; which our senses determine by its position to bodies; and which is vulgarly taken for immovable space; such is the dimension of a subterraneaneous, an �real, or celestial space, determined by its position in respect of the earth. Absolute and relative space, are the same in figure and magnitude; but they do not remain always numerically the same. For if the earth, for instance, moves, a space of our air, which relatively and in respect of the earth remains always the same, will at one time be one part of the absolute space into which the air passes; at another time it will be another part of the same, and so, absolutely understood, it will be perpetually mutable." --Newton. "The introduction of a ``luminiferous ether'' will prove to be superfluous inasmuch as the view here to be developed will not require an ``absolutely stationary space'' provided with special properties, BUT ... "It is essential to have time defined by means of stationary clocks in the stationary system, and the time now defined being appropriate to the stationary system we call it ``the time of the stationary system.'' -- Einstein.
From: Darwin123 on 30 May 2010 15:17 On May 29, 12:25 pm, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "Darwin123" <drosen0...(a)yahoo.com> wrote in message > I am not accusing Newton of making a rather empty statement. > Newton's "absolute frame" is not privileged any more than Einstein's > "stationary frame". Androcles quoting Einstein > ================================================== .....<Lots of words Androcles didn't understand. One reference to aether, one of Androcles favorite subjects. > "The introduction of a ``luminiferous ether'' will prove to be superfluous > inasmuch as the view here to be developed will not require an ``absolutely > stationary space'' provided with special properties, BUT ... > "It is essential to have time defined by means of stationary clocks in the > stationary system, and the time now defined being appropriate to the > stationary system we call it ``the time of the stationary system.'' -- > Einstein. The aether was just as superfluous in Newton's universe as it is in Einstein's universe. Newton thought light acted like a particle, rather than like a wave. To be fair, Newton either didn't know or didn't understand about the experiments which showed light acted like a wave. According to Newton, all particles (including light corpusules) acted under the laws described in Principia. Principia, which were the "laws of mechanics," did not describe an aether. Absolute space was completely different from the aether. The aether does not obey the laws of Principia, even in the absolute space reference frame. The laws of the universe, in Principia, are Galilean invariant. The aether is not Galilean invariant. In Newton's universe, light traveled in absolute space according to Principia. One can construct another coordinate system where Principia applied merely by applying a Galilean transform. The aether was completely unnecessary if light really consisted of corpusules. Scientists learned more about light, electricity and magnetism after Newton died. Principia clearly did not apply to electric and magnetic forces. The experiments by Faraday, Marconi and Hertz clearly showed that electricity and magnetism did not obey Principia. Principia clearly did not apply to light. Light was not comprised of light corpusules, as Newton imagined them. Although Principia seemed to apply to atoms and electrons, it did not apply to light waves. Maxwell's equations seemed to apply to light, electricity, and magnetism. Einstein proposed that there was at least one stationary frame where both Principia applied to atoms and electrons, while Maxwell's equations applied to light, electric fields, and magnetic fields. With regards to atoms and electrons, the aether is obviously superfluous. Even Newton would have agreed with that, so long as the discussion was restricted to atoms and electrons. Einstein's extension is that the aether is even superfluous with regards to electric and magnetic fields. The laws of Principia, and Maxwell's equations, always apply in at least one stationary frame. The conditions that the laws of mechanics applies in the stationary frame for atoms and electrons is actually very restrictive. Not every frame can be a stationary frame. This idea some people have that ALL frames can be stationary is nonsense, even according to Einstein's theory in 1905. However, there are an infinite number of different frames in which the laws of Principia also apply. Your quotation from Einstein does not support any of your conclusions. The aether is not equivalent to absolute space. The aether is inconsistent with the idea of absolute space, as described by Newton. The idea of invariance is fundamental to both the ideas of Newton and the ideas of Einstein. The laws of Principia are invariant to Galilean transformations. The laws of SR are invariant to the Lorentz transformation. The laws of GR are invariant to the covariant transformation. The transformations are fundamental, while the aether is superfluous. Newton may disagree with Einstein at many interesting points, but he would agree on one issue. The luminiferous aether is superfluous. Both Newton and Einstein found the aether unnecessary and misleading in terms of the systems that they studied.
From: valls on 31 May 2010 15:09 On 27 mayo, 12:58, PD <thedraperfam...(a)gmail.com> wrote: > On May 26, 3:49 pm, va...(a)icmf.inf.cu wrote: > > > > > > > On 25 mayo, 10:46, PD <thedraperfam...(a)gmail.com> wrote:> On May 25, 10:19 am, va...(a)icmf.inf.cu wrote: > > > > The frames you mentioned are not inertial. Circularly moving bodies > > > are not in inertial motion. > > > Let us revise what kind of reference frames are managing 1905 > > Einstein. At the beginning of paragraph 1 (30Jun1905 paper) we can > > read: > > [Let us take a system of co-ordinates in which the equations of > > Newtonian mechanics hold good.] > > That type of system is denoted by 1905 Einstein stationary system.. > > By the way, in all his 1905 text he not use the word inertial, but > > taking into account that the equations of Newtonian mechanics hold > > good (and then also all its laws, including the first), I consider > > safe to interpret that stationary system is what today is named > > inertial frame. But in all 1905 text we dont find any mention at > > all about a possible movement of the stationary system, and much less > > specifying that it must be with uniform velocity following a straight > > line. > > Again, it is dangerous to read a paper in isolation. > I am NOT reading the paper in isolation at all. I am taking into account ALL its past well separated from ALL its future. The past for use in its interpretation, and the future for NOT use in it, being that last part the very dangerous mistake if not done. > In circularly moving reference frames, the Newtonian laws of motion do > not hold. There are acceleration terms that do not arise as the result > of any force that would be consistent with Newton's 3rd law. The > Coriolis effect is an excellent example. > We are in total agreement that an accelerated entity is NOT an inertial frame that you can use to refer the moving of bodies in its exterior. But that entity CAN be considered an inertial frame for its interior, but only if the acceleration that the external world provokes in it as a whole is (sufficiently approximate) the same in all its internal component bodies (and then not been noted by them at all). That is the case, for example, with the today very successfully GPS ECI (the same used by 1905 Einstein at the end of paragraph 4 in his 30June1905 paper). For internal use, the ECI centre of mass can be considered at rest, with the external word (principally the Moon and the Sun) provoking in it an almost same acceleration in all its internal component bodies (Earth and GPS clocks, in satellites or at ground, the ECI body set). Externally, the whole ECI as a component part of the Solar System is moving circularly (really in a very much complex trajectory if you take into account the presence of the Moon). You can use the ECI ONLY with bodies taking into account when determining the centre of mass. The external use of ANY centre of mass inertial frame to describe the movement of a body that it is not in its body set implies (as you correctly say) a violation of Newtons laws (try to describe the Suns trajectory in the ECI!). The ECI (as any other centre of mass system) can be inertial only for its interior, NOT for its exterior. > > At the end of paragraph 4 in the 30Jun1905 paper, we find as the > > stationary system what today is denoted GPS ECI, the real Earth > > rotating in the inertial frame determined by itself with its centre of > > mass at rest (as all the rotating axis, including the poles). We find > > there also as the moving system a clock at the equator moving in a > > CIRCULAR path. > > Yes, indeed, and there was a considerable amount of controversy about > whether this construction should be considered movement in an inertial > frame. It was only later that Einstein treated it better. > (Maintain for the moment the later Einstein out, as we are considering here only the 1905 one). By sure 1905 Einsteins moving system cant be consider at all in general as an inertial frame. See the last part of paragraph 4 where he refers to a clock moving in a continuous curved line (here is where he introduced at the end the rotating Earth with clocks at a pole and at the equator). Even if he refers here only to a constant speed circular movement, the today experimental evidence of GPS seem to support that ANY movement of the moving system can be described with 1905 Einstein formulas considering any velocity as an instantaneous uniform one using the differential and integral calculus procedures. The moving system can be considered an inertial frame for its interior only under the equal acceleration condition that I refer in my last comment. > > > > Taking into account that in a 1905R (without absolute > > space and time) all inertial frames must be derived from the bodies > > themselves, the stationary system must be then some CM inertial frame, > > being the moving system any of its component bodies that can be moving > > in any way compatible with Newtons laws. All this is supported with > > the huge GPS ECI experimental evidence. Note that the Solar System > > (SS) can be considered at rest as a whole entity (the more exact > > inertial frame known by men) for internal affairs, but moving not in > > the inertial way as a component of the Galaxy. The Earth, an SS > > component, is in a similar situation. Considered at rest for internal > > affairs (the GPS very successful function!), but moving not in the > > inertial way as a part of SS. All seem to indicate that without > > absolute space and time, what characterize the inertial attribute of a > > system as a whole is only the rest (v=0) of its CM, not the any > > uniform velocity v movement (that seem to belong only to the Newtonian > > infinite empty inertial frames already put out in 1905 Relativity). As > > the title of this thread states, according to 1905 Relativity, a > > single material point (modelling an inertial frame) must be always at > > rest. Because already it is not present the absolute space and time > > permitting it to move with any uniform v velocity. RVHG (Rafael Valls Hidalgo-Gato)
From: valls on 31 May 2010 16:20
On 28 mayo, 12:32, PD <thedraperfam...(a)gmail.com> wrote: > On May 28, 11:06 am, va...(a)icmf.inf.cu wrote: > > > > > > > On 28 mayo, 09:01, PD <thedraperfam...(a)gmail.com> wrote: > > > > On May 28, 8:55 am, va...(a)icmf.inf.cu wrote: > > > > > On 27 mayo, 10:52, harald <h...(a)swissonline.ch> wrote: > > > > > > On May 24, 12:47 pm, va...(a)icmf.inf.cu wrote:> On 21 mayo, 04:35, harald <h...(a)swissonline.ch> wrote: > > > > > > [..] > > > > > > > > > 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? > > > > > > In SRT we are free to choose which Newtonian coordinate system we call > > > > > "moving" and which one "stationary"; as they are equally valid for the > > > > > laws of physics, not one of the two is preferred. The only way in > > > > > which "mass" is relevant is that it is convenient to choose a high > > > > > mass object as approximation for a Newtonian reference system. That is > > > > > at odds with your introduction of "body sets" and your preference for > > > > > calling certain "centre of mass" systems "stationary" and not > > > > > "moving". And here below you do it again... > > > > > We are not addressing here SR theory, but 1905R one. That they are > > > > different theories can be checked very easily. > > > > No, they are not. They are different presentations of growing > > > sophistication of the SAME theory. > > > Comment then my arguments showing why they are different theories. > > Explain to me then why being Gravity out of the scope of SR, in the > > 1905R we find as an example the rotating Earth as the stationary > > system and a clock at the equator as the moving system gravitational > > centripetal accelereted with a CIRCULAR trajectory! Being the Earth > > also gravitational centripetal accelerated by the Sun, explain to me > > what kind of inertial systems are managing 1905 Einstein with Gravity > > present. Where are the movements with uniform linear velocities > > characteristic of inertial frames in SR? > > Can you consider the (moving) clock at the equator at rest, with the > > clock (at rest in the pole) moving with respect to it? Are not all > > inertial frames equivalent ones? Are not all of them equivalent to > > describe our Universe? Try to describe the Sun's trajectory in the GPS > > ECI frame, the same one that is the stationary system in the 1905R > > example. When you showed me the Sun's trajectory in the ECI I will > > trust in you when saying that SR and 1905R are the same theory. If you > > can't do it, you must explain me in detail why it is imposible to > > describe the Sun's trajectory in the ECI without violating the > > Newton's laws that define an stationary system in 1905R. > > > RVHG (Rafael Valls Hidalgo-Gato) > > Indeed, and again this points to the problem of reading papers in > isolation, and also considering a seminal paper to be the complete > presentation of a theory. The "1905R" paper you mention is NOT a > complete explication of special relativity, let alone relativity. It > is the FIRST explication of special relativity, and as such it has a > number of hanging threads, unfinished business, only partly explicated > answers, superficially understood and explained concepts, and so on. > (In other post I answered you already about me reading a paper in isolation, being the true that I am taking into account ALL its past and ALL its future, the past for using in the interpretation, and the future for NOT using in it). We are in agreement about that hardly the first paper about any thing can be already the complete presentation of a theory. Note for example with what emphasis 1905 Einstein start talking about the material character of the frames, identifying system of coordinates with rigid bodies, describing Cartesian coordinates as a system of 3 rigid material lines, etc. And taking into account that a single material point is already an entity with mass in the Newtonian mechanics (that hold good by definition in any 1905 Einstein stationary system), we can understand that the presence of mass is essential in the new theory. Remember that 1905 Einstein takes out the privileged absolute frame (and with it all the derived moving with all possible velocities frames), remaining only the material massive bodies themselves to determine any inertial frame. Even then, 1905 Einstein leave this point without any further theoretical development, what I consider a weak point in the theory. Fortunately, he put our beloved massive rotating Earth as the unique real example in all his text, also fortunately supported by the huge experimental evidence of today GPS, permitting us to have a secure reference point to help us when deciding which are the hanging threads, unfinished business, only partly explicated answers, superficially understood and explained concepts, and so on that must be corrected in his theory first imperfect version. I know that 1907 Minkowski introduces substantial changes in the theory considering infinite completely equivalent inertial frames, without any relation at all with massive bodies. For that reason, I consider that step a re-introduction of the infinite inertial frames present in the previous Newtonian view, even if now without the privileged absolute one and a new very strong relationship between space and time. To take out the imaginary absolute frame and maintain the also imaginary infinite derived ones (similar to disappearing the first floor of a building and maintaining in use all the derived ones over it) doesnt seem to me an acceptable logic step. But what really makes me to decide that the 1907 Minkowski view must not be considered the unique possible alternative, is the presence in it of the total equivalence between all the imaginary infinite frames, erasing all difference between stationary system and moving system, with the totally absurd implication (already experimentally proved false with the GPS function) that the clock at the pole (the unique experimentally confirmed rest one) is moving with respect to a rest clock at the equator (the unique experimentally confirmed moving one). Any number of experiments cant prove true a theory, but a single one can prove false one. Fortunately, nobody can take out from history the real rotating Earth example (already proved experimentally correct) from the 1905 text. To convince us that stationary system and moving system are NOT the same concept in 1905 Relativity, it is sufficient to read the second postulate version that appears at the beginning of paragraph 2: 2. Any ray of light moves in the stationary system of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body. Hence As you see, something so essential as a postulate refers only to stationary frames, putting in evidence the non-equivalent character between stationary and moving frames in 1905 Relativity. Other strong evidence supporting the difference between stationary and moving is in the title (and also content, of course) of paragraph 3, where you can see that the transformation of coordinates and times is only FROM the stationary TO the moving system. > For example, the 1905R paper makes a statement about the laws of > physics in *inertial* reference frames, which had a very well > understood meaning in physics well before this paper, and was not > replaced in meaning by this paper. However, as you noted, Einstein > attempted to bend this statement to apply the principle to a > NONinertial frame, that inhabited by a clock at the Earth's equator. > This iffy application was noted by people working on relativity after > this paper, including Einstein himself, and there were a couple of > outcomes from this specific example. One was the more complete > calculation of the effect per general relativity. Another was the > discovery that accelerating reference frames could be analyzed with > care using special relativity. Both these results came well after the > 1905R paper, but are both part of relativity -- or, more > appropriately, part of the relativistic aspects of nature that were > being discovered by physicists in this time period. > > PD I had showed you already that the real rotating Earth case presented by 1905 Einstein is explained completely by his theory and confirmed by today huge GPS experimental evidence. About your GR reference, you are already in the process to verify by yourself that using only 1905R, the behaviour of atomic clocks in gravitational fields can be explained (of course, I can't force you at all to do that, maybe you prefer a similar alternative to the one chosen by some historic personage when refusing to see through Galileos telescope to observe by himself the Jupiter satellites). An all Physics laws remain being the same in all inertial frames (now well identified as all possible centre of mass inertial frames where the external world applies a sufficiently almost same acceleration in all its components). RVHG (Rafael Valls Hidalgo-Gato) |