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From: valls on 21 Jul 2010 09:13
On 20 jul, 16:54, PD <thedraperfam...(a)gmail.com> wrote:
> On Jul 20, 2:37 pm, va...(a)icmf.inf.cu wrote:
>
>
>
>
>
> > On 20 jul, 10:19, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Jul 19, 6:03 pm, va...(a)icmf.inf.cu wrote:
>
> > > > On 19 jul, 15:20, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > On Jul 19, 2:17 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > > On 19 jul, 08:36, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > On Jul 19, 3:35 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > On 16 jul, 16:39, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > > > On Jul 16, 11:31 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > > > > > Old fart, Tycho Brache already did that hundreds of years ago.
>
> > > > > > > > > > > > The ECI is a centre of mass inertial frame, in both the Newtonian view
> > > > > > > > > > > > and the 1905 Relativity one, in both holding good the Newtonian
> > > > > > > > > > > > mechanical laws. And you must know that it is absolutely impossible to
> > > > > > > > > > > > describe a Sun moving with respect to an Earth at rest following
> > > > > > > > > > > > Newton’s laws (Tycho Brahe’s work precedes Newton’s one).
>
> > > > > > > > > > > You are an imbecile, old fart.
>
> > > > > > > > > > > > To describe
> > > > > > > > > > > > the Sun’s trajectory you need to consider the Galaxy centre of mass
> > > > > > > > > > > > inertial frame (or maybe a greater one),
>
> > > > > > > > > > > No, old fart. You can use ANY frame. This is the whole point of
> > > > > > > > > > > relativity.
>
> > > > > > > > > > If you insist, describe then the Sun's trajectory in the ECI.
>
> > > > > > > > > Old fart, Tycho Brahe already did this almost 600 years ago. How dense
> > > > > > > > > are you?
>
> > > > > > > > We are talking here about inertial frames, the ones denoted by 1905
> > > > > > > > Einstein stationary systems, in which the equations of Newtonian
> > > > > > > > mechanics hold good. I insist, describe the Sun's trajectory in the
> > > > > > > > ECI using Newton's laws.
>
> > > > > > > Imbecile, Tycho Brahe already showed how this can be done 600 years
> > > > > > > ago. See here :http://www.mathpages.com/rr/s8-01/8-01.htm
>
> > > > > > Incredible! Tycho Brahe using Newton's laws. Surely he made a time
> > > > > > travel.
>
> > > > > I'm sorry, I don't understand. One can describe a trajectory by either
> > > > > detailed observation or by theoretical prediction, and in fact one
> > > > > should have both and compare them to see if the theory is any good.
> > > > > But Brahe's data are quite good descriptions of the trajectories.
>
> > > > > Are you claiming that Newton's laws cannot describe motion from a
> > > > > center-of-mass coordinate?
>
> > > > By the contrary, what I am claiming is that in 1905 Relativity the
> > > > unique inertial frames are the centre of mass ones, and they are
> > > > precisely the stationary systems in which Newtonian equations hold
> > > > good.
>
> > > I'm sorry but this is not correct. I've already mentioned this.
> > > Taking an ordinary example, you can look at the collision of a cue
> > > ball with a set of billiard balls on a table. You may take, for
> > > example, the laws of conservation of energy and momentum as relevant
> > > laws of physics. You can verify that those laws hold in the frame
> > > where the center of mass of this system of balls is at rest, and you
> > > can also verify that these laws hold in the frame where the center of
> > > mass of this system has constant velocity in any direction and in any
> > > amount. It is this set of frames (and there is an infinite number of
> > > them) in which the laws of mechanics hold, and it is this set of
> > > frames that are the inertial ones.
>
> > > If you've not been through this simple exercise in freshman mechanics,
> > > then you were poorly served in your education.
>
> > When you select some body set to consider its centre of mass inertial
> > frame, you are making a model of some part of Nature. There exist here
> > some implicit assumptions. One of them is that you consider all the
> > bodies in the set modelled by a material point (to be able to compute
> > the position of the centre of mass from the positions of the bodies).
> > Another one is to consider the body set the whole Universe, in the
> > model doesn’t exist any other body (for example, when 1913 N.Bohr made
> > his H atom model, he considers an electron and a proton as the unique
> > bodies in the Universe). The fact is that the existence of any other
> > body alters the position of the centre of mass, and there exist a
> > unique centre of mass system for any determined starting body set.
>
> OK, let's stop right there and please reread again what I said. I am
> looking at a FIXED (16 ball) set of objects. The laws of conservation
> of momentum and energy describe the behavior of this system in a
> particular inertial reference frame, that where the center of mass of
> the system is stationary. However, the SAME laws of conservation of
> momentum and energy describe the behavior of this SAME system in any
> other reference frame that where the center of mass of this SAME
> system is moving at constant velocity with any magnitude and any
> direction. That statement is what the principle of relativity is
> about.
>
> I am not adding any other bodies to the system, nor am I considering
> the entire universe to be the system.
>
Of course that you implicitly is considering the 16 balls the entire
universe, when you don’t take into account the mass of other bodies
when determining the centre of mass. Let me substitute your example
for the ECI to have at hand its huge experimental evidence. When in
the GPS ECI the centre of mass is determined, even the Moon is
considered not existing, and of course, that centre is considered at
rest. You argue that this centre of mass can be considered moving with
any uniform velocity (with respect to what?). This implies the re-
introduction of the imaginary (not related with bodies) inertial
frames already put out by 1905 Einstein. Implicitly you are supposing
the ECI the absolute frame, changing then to a relative and apparent
inertial frame (using Newton’s denotations). What can be the purpose
of that change? Absolutely nothing. All the useful information is
already contained in the bodies belonging to the selected body set.
The added uniform velocity (with respect to nothing) is like the
introduction of a strange root when solving an equation. To put it in
the model is absurd, it represents nothing in the real world (by the
way, being imaginary the new frame introduced, it is absolutely
impossible to make any real measurement in or on it -no real bodies
related with it-, allowing to its fans maintain endless discussions in
this group about its existence). But if now you want to consider the
relation of the ECI with its external real world, you can extend the
body set according to your new needs, per example considering the
Earth-Moon System or the whole Solar System, where the Earth-Moon has
its very definite velocity (about 30 Km/s). And now is the centre of
mass of the Solar System the one at rest. Almost sure in a near future
we will be talking about what I denote (since many years) a
Hierarchical Inertial System (HIS). Surely you are already guessing
what a HIS means.

In the 1905 text we can find two versions for the Principle of
Relativity, the first taking about the same laws in all inertial
frames, and a second one talking about the same laws in two frames
moving with any relative uniform velocity. The literal text is the
following (0 is for Introduction, 2 for paragraph 2):

0-1. The same laws of electrodynamics and optics will be valid for all
frames of reference for which the equations of mechanics hold good.
2-1. The laws by which the states of physical systems undergo changes
are not affected, whether these changes of state be referred to the
one or the other of two systems of co-ordinates in uniform translatory
motion.

I prefer the first 0-1version. Surely you prefer the 2-1 one.

RVHG (Rafael Valls Hidalgo-Gato)
From: PD on 21 Jul 2010 09:27
On Jul 21, 8:13 am, va...(a)icmf.inf.cu wrote:
> On 20 jul, 16:54, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Jul 20, 2:37 pm, va...(a)icmf.inf.cu wrote:
>
> > > On 20 jul, 10:19, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > On Jul 19, 6:03 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > On 19 jul, 15:20, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > > On Jul 19, 2:17 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > > > On 19 jul, 08:36, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > > On Jul 19, 3:35 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > On 16 jul, 16:39, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > > > > On Jul 16, 11:31 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > > > > > > Old fart, Tycho Brache already did that hundreds of years ago.
>
> > > > > > > > > > > > > The ECI is a centre of mass inertial frame, in both the Newtonian view
> > > > > > > > > > > > > and the 1905 Relativity one, in both holding good the Newtonian
> > > > > > > > > > > > > mechanical laws. And you must know that it is absolutely impossible to
> > > > > > > > > > > > > describe a Sun moving with respect to an Earth at rest following
> > > > > > > > > > > > > Newton’s laws (Tycho Brahe’s work precedes Newton’s one).
>
> > > > > > > > > > > > You are an imbecile, old fart.
>
> > > > > > > > > > > > > To describe
> > > > > > > > > > > > > the Sun’s trajectory you need to consider the Galaxy centre of mass
> > > > > > > > > > > > > inertial frame (or maybe a greater one),
>
> > > > > > > > > > > > No, old fart. You can use ANY frame. This is the whole point of
> > > > > > > > > > > > relativity.
>
> > > > > > > > > > > If you insist, describe then the Sun's trajectory in the ECI.
>
> > > > > > > > > > Old fart, Tycho Brahe already did this almost 600 years ago. How dense
> > > > > > > > > > are you?
>
> > > > > > > > > We are talking here about inertial frames, the ones denoted by 1905
> > > > > > > > > Einstein stationary systems, in which the equations of Newtonian
> > > > > > > > > mechanics hold good. I insist, describe the Sun's trajectory in the
> > > > > > > > > ECI using Newton's laws.
>
> > > > > > > > Imbecile, Tycho Brahe already showed how this can be done 600 years
> > > > > > > > ago. See here :http://www.mathpages.com/rr/s8-01/8-01.htm
>
> > > > > > > Incredible! Tycho Brahe using Newton's laws. Surely he made a time
> > > > > > > travel.
>
> > > > > > I'm sorry, I don't understand. One can describe a trajectory by either
> > > > > > detailed observation or by theoretical prediction, and in fact one
> > > > > > should have both and compare them to see if the theory is any good.
> > > > > > But Brahe's data are quite good descriptions of the trajectories.
>
> > > > > > Are you claiming that Newton's laws cannot describe motion from a
> > > > > > center-of-mass coordinate?
>
> > > > > By the contrary, what I am claiming is that in 1905 Relativity the
> > > > > unique inertial frames are the centre of mass ones, and they are
> > > > > precisely the stationary systems in which Newtonian equations hold
> > > > > good.
>
> > > > I'm sorry but this is not correct. I've already mentioned this.
> > > > Taking an ordinary example, you can look at the collision of a cue
> > > > ball with a set of billiard balls on a table. You may take, for
> > > > example, the laws of conservation of energy and momentum as relevant
> > > > laws of physics. You can verify that those laws hold in the frame
> > > > where the center of mass of this system of balls is at rest, and you
> > > > can also verify that these laws hold in the frame where the center of
> > > > mass of this system has constant velocity in any direction and in any
> > > > amount. It is this set of frames (and there is an infinite number of
> > > > them) in which the laws of mechanics hold, and it is this set of
> > > > frames that are the inertial ones.
>
> > > > If you've not been through this simple exercise in freshman mechanics,
> > > > then you were poorly served in your education.
>
> > > When you select some body set to consider its centre of mass inertial
> > > frame, you are making a model of some part of Nature. There exist here
> > > some implicit assumptions. One of them is that you consider all the
> > > bodies in the set modelled by a material point (to be able to compute
> > > the position of the centre of mass from the positions of the bodies).
> > > Another one is to consider the body set the whole Universe, in the
> > > model doesn’t exist any other body (for example, when 1913 N.Bohr made
> > > his H atom model, he considers an electron and a proton as the unique
> > > bodies in the Universe). The fact is that the existence of any other
> > > body alters the position of the centre of mass, and there exist a
> > > unique centre of mass system for any determined starting body set.
>
> > OK, let's stop right there and please reread again what I said. I am
> > looking at a FIXED (16 ball) set of objects. The laws of conservation
> > of momentum and energy describe the behavior of this system in a
> > particular inertial reference frame, that where the center of mass of
> > the system is stationary. However, the SAME laws of conservation of
> > momentum and energy describe the behavior of this SAME system in any
> > other reference frame that where the center of mass of this SAME
> > system is moving at constant velocity with any magnitude and any
> > direction. That statement is what the principle of relativity is
> > about.
>
> > I am not adding any other bodies to the system, nor am I considering
> > the entire universe to be the system.
>
> Of course that you implicitly is considering the 16 balls the entire
> universe, when you don’t take into account the mass of other bodies
> when determining the centre of mass.

No. Perhaps you don't understand the meaning of "system" in physics.
You can draw an imaginary surface around any collection of objects and
that is a system in physics. Some systems can be (for the purposes of
the analysis at hand) be considered isolated and others not isolated.
Conservation of momentum and conservation of energy are statements
about such systems.

This in no way presumes that the system is the entire universe.

There is a reason why I asked you to consider this example, rather
than your favorite planetary system examples. I'd like for you do
understand what these concepts mean in ordinary, everyday applications
such as is found in a freshman physics text.

I understand now that you haven't yet gotten a grasp of basic concepts
from freshman physics.

> Let me substitute your example
> for the ECI to have at hand its huge experimental evidence. When in
> the GPS ECI the centre of mass is determined, even the Moon is
> considered not existing, and of course, that centre is considered at
> rest. You argue that this centre of mass can be considered moving with
> any  uniform velocity (with respect to what?). This implies the re-
> introduction of the imaginary (not related with bodies) inertial
> frames already put out by 1905 Einstein. Implicitly you are supposing
> the ECI the absolute frame, changing then to a relative and apparent
> inertial frame (using Newton’s denotations). What can be the purpose
> of that change? Absolutely nothing. All the useful information is
> already contained in the bodies belonging to the selected body set.
> The added uniform velocity (with respect to nothing) is like the
> introduction of a strange root when solving an equation. To put it in
> the model is absurd, it represents nothing in the real world (by the
> way, being imaginary the new frame introduced, it is absolutely
> impossible to make any real measurement in or on it -no real bodies
> related with it-, allowing to its fans maintain endless discussions in
> this group about its existence). But if now you want to consider the
> relation of the ECI with its external real world, you can extend the
> body set according to your new needs, per example considering the
> Earth-Moon System or the whole Solar System, where the Earth-Moon has
> its very definite velocity (about 30 Km/s). And now is the centre of
> mass of the Solar System the one at rest. Almost sure in a near future
> we will be talking about what I denote (since many years) a
> Hierarchical Inertial System (HIS). Surely you are already guessing
> what a HIS means.
>
> In the 1905 text we can find two versions for the Principle of
> Relativity, the first taking about the same laws in all inertial
> frames, and a second one talking about the same laws in two    frames
> moving with any relative uniform velocity. The literal text is the
> following (0 is for Introduction, 2 for paragraph 2):
>
> 0-1. The same laws of electrodynamics and optics will be valid for all
> frames of reference for which the equations of mechanics hold good.
> 2-1. The laws by which the states of physical systems undergo changes
> are not affected, whether these changes of state be referred to the
> one or the other of two systems of co-ordinates in uniform translatory
> motion.
>
> I prefer the first 0-1version. Surely you prefer the 2-1 one.
>
> RVHG (Rafael Valls Hidalgo-Gato)- Hide quoted text -
>
> - Show quoted text -

From: valls on 21 Jul 2010 16:33
On 21 jul, 08:27, PD <thedraperfam...(a)gmail.com> wrote:
> On Jul 21, 8:13 am, va...(a)icmf.inf.cu wrote:
>
>
>
>
>
> > On 20 jul, 16:54, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Jul 20, 2:37 pm, va...(a)icmf.inf.cu wrote:
>
> > > > On 20 jul, 10:19, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > On Jul 19, 6:03 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > > On 19 jul, 15:20, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > > > On Jul 19, 2:17 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > On 19 jul, 08:36, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > > > On Jul 19, 3:35 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > > On 16 jul, 16:39, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > > > > > On Jul 16, 11:31 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > > > > > > > Old fart, Tycho Brache already did that hundreds of years ago.
>
> > > > > > > > > > > > > > The ECI is a centre of mass inertial frame, in both the Newtonian view
> > > > > > > > > > > > > > and the 1905 Relativity one, in both holding good the Newtonian
> > > > > > > > > > > > > > mechanical laws. And you must know that it is absolutely impossible to
> > > > > > > > > > > > > > describe a Sun moving with respect to an Earth at rest following
> > > > > > > > > > > > > > Newton’s laws (Tycho Brahe’s work precedes Newton’s one).
>
> > > > > > > > > > > > > You are an imbecile, old fart.
>
> > > > > > > > > > > > > > To describe
> > > > > > > > > > > > > > the Sun’s trajectory you need to consider the Galaxy centre of mass
> > > > > > > > > > > > > > inertial frame (or maybe a greater one),
>
> > > > > > > > > > > > > No, old fart. You can use ANY frame. This is the whole point of
> > > > > > > > > > > > > relativity.
>
> > > > > > > > > > > > If you insist, describe then the Sun's trajectory in the ECI.
>
> > > > > > > > > > > Old fart, Tycho Brahe already did this almost 600 years ago. How dense
> > > > > > > > > > > are you?
>
> > > > > > > > > > We are talking here about inertial frames, the ones denoted by 1905
> > > > > > > > > > Einstein stationary systems, in which the equations of Newtonian
> > > > > > > > > > mechanics hold good. I insist, describe the Sun's trajectory in the
> > > > > > > > > > ECI using Newton's laws.
>
> > > > > > > > > Imbecile, Tycho Brahe already showed how this can be done 600 years
> > > > > > > > > ago. See here :http://www.mathpages.com/rr/s8-01/8-01.htm
>
> > > > > > > > Incredible! Tycho Brahe using Newton's laws. Surely he made a time
> > > > > > > > travel.
>
> > > > > > > I'm sorry, I don't understand. One can describe a trajectory by either
> > > > > > > detailed observation or by theoretical prediction, and in fact one
> > > > > > > should have both and compare them to see if the theory is any good.
> > > > > > > But Brahe's data are quite good descriptions of the trajectories.
>
> > > > > > > Are you claiming that Newton's laws cannot describe motion from a
> > > > > > > center-of-mass coordinate?
>
> > > > > > By the contrary, what I am claiming is that in 1905 Relativity the
> > > > > > unique inertial frames are the centre of mass ones, and they are
> > > > > > precisely the stationary systems in which Newtonian equations hold
> > > > > > good.
>
> > > > > I'm sorry but this is not correct. I've already mentioned this.
> > > > > Taking an ordinary example, you can look at the collision of a cue
> > > > > ball with a set of billiard balls on a table. You may take, for
> > > > > example, the laws of conservation of energy and momentum as relevant
> > > > > laws of physics. You can verify that those laws hold in the frame
> > > > > where the center of mass of this system of balls is at rest, and you
> > > > > can also verify that these laws hold in the frame where the center of
> > > > > mass of this system has constant velocity in any direction and in any
> > > > > amount. It is this set of frames (and there is an infinite number of
> > > > > them) in which the laws of mechanics hold, and it is this set of
> > > > > frames that are the inertial ones.
>
> > > > > If you've not been through this simple exercise in freshman mechanics,
> > > > > then you were poorly served in your education.
>
> > > > When you select some body set to consider its centre of mass inertial
> > > > frame, you are making a model of some part of Nature. There exist here
> > > > some implicit assumptions. One of them is that you consider all the
> > > > bodies in the set modelled by a material point (to be able to compute
> > > > the position of the centre of mass from the positions of the bodies).
> > > > Another one is to consider the body set the whole Universe, in the
> > > > model doesn’t exist any other body (for example, when 1913 N.Bohr made
> > > > his H atom model, he considers an electron and a proton as the unique
> > > > bodies in the Universe). The fact is that the existence of any other
> > > > body alters the position of the centre of mass, and there exist a
> > > > unique centre of mass system for any determined starting body set.
>
> > > OK, let's stop right there and please reread again what I said. I am
> > > looking at a FIXED (16 ball) set of objects. The laws of conservation
> > > of momentum and energy describe the behavior of this system in a
> > > particular inertial reference frame, that where the center of mass of
> > > the system is stationary. However, the SAME laws of conservation of
> > > momentum and energy describe the behavior of this SAME system in any
> > > other reference frame that where the center of mass of this SAME
> > > system is moving at constant velocity with any magnitude and any
> > > direction. That statement is what the principle of relativity is
> > > about.
>
> > > I am not adding any other bodies to the system, nor am I considering
> > > the entire universe to be the system.
>
> > Of course that you implicitly is considering the 16 balls the entire
> > universe, when you don’t take into account the mass of other bodies
> > when determining the centre of mass.
>
> No. Perhaps you don't understand the meaning of "system" in physics.
> You can draw an imaginary surface around any collection of objects and
> that is a system in physics. Some systems can be (for the purposes of
> the analysis at hand) be considered isolated and others not isolated.
> Conservation of momentum and conservation of energy are statements
> about such systems.
>
> This in no way presumes that the system is the entire universe.
>
When you have a center of mass inertial system, you can use it only to
describe the bodies taking into account when determining that centre
of mass. In your 16 balls system, you can’t use it for example to
describe an added 17 ball, because the presence of the new ball
changes the centre of mass. The description of the new ball can’t be
done without a violation of Newton’s laws, your now 17 balls system is
not an inertial system if you pretend to consider at rest the old
centre of mass. Then, when using any centre of mass inertial frame,
there exist always the implicit assumption that the bodies taking into
account to determine the centre of mass is the entire universe
(without any other body in its exterior). This is simple freshman
physics, for any body set there exists a unique center of mass
inertial system corresponding to it.
> There is a reason why I asked you to consider this example, rather
> than your favorite planetary system examples. I'd like for you do
> understand what these concepts mean in ordinary, everyday applications
> such as is found in a freshman physics text.
>
> I understand now that you haven't yet gotten a grasp of basic concepts
> from freshman physics.
>
The Physics laws are the same in all inertial systems, no matter if
you are considering balls, planets or any other kind of objects. I
can’t understand your objection. The GPS is precisely the best example
of an ordinary, everyday application. Very much useful than the ones
you can find in a freshman physics text to understand basic physics
concepts, because it refers to something real that is in a continuous
function with huge experimental evidence. In it is applied Newtonian
mechanics, Special Relativity and General Relativity, a wonderful mix
covering all the spectrum of today physics concepts with the most
exact and accurate physical measurements, ideal for our purposes here.
Maybe you don’t know what the Global Positioning System (GPS) is? If
not, I apologize you in advance for assuming your knowledge of it.
Whatever the case, you can consider that all what I say about the ECI
is also about your 16 balls system.
>
>
> > Let me substitute your example
> > for the ECI to have at hand its huge experimental evidence. When in
> > the GPS ECI the centre of mass is determined, even the Moon is
> > considered not existing, and of course, that centre is considered at
> > rest. You argue that this centre of mass can be considered moving with
> > any  uniform velocity (with respect to what?). This implies the re-
> > introduction of the imaginary (not related with bodies) inertial
> > frames already put out by 1905 Einstein. Implicitly you are supposing
> > the ECI the absolute frame, changing then to a relative and apparent
> > inertial frame (using Newton’s denotations). What can be the purpose
> > of that change? Absolutely nothing. All the useful information is
> > already contained in the bodies belonging to the selected body set.
> > The added uniform velocity (with respect to nothing) is like the
> > introduction of a strange root when solving an equation. To put it in
> > the model is absurd, it represents nothing in the real world (by the
> > way, being imaginary the new frame introduced, it is absolutely
> > impossible to make any real measurement in or on it -no real bodies
> > related with it-, allowing to its fans maintain endless discussions in
> > this group about its existence). But if now you want to consider the
> > relation of the ECI with its external real world, you can extend the
> > body set according to your new needs, per example considering the
> > Earth-Moon System or the whole Solar System, where the Earth-Moon has
> > its very definite velocity (about 30 Km/s). And now is the centre of
> > mass of the Solar System the one at rest. Almost sure in a near future
> > we will be talking about what I denote (since many years) a
> > Hierarchical Inertial System (HIS). Surely you are already guessing
> > what a HIS means.
>
> > In the 1905 text we can find two versions for the Principle of
> > Relativity, the first taking about the same laws in all inertial
> > frames, and a second one talking about the same laws in two    frames
> > moving with any relative uniform velocity. The literal text is the
> > following (0 is for Introduction, 2 for paragraph 2):
>
> > 0-1. The same laws of electrodynamics and optics will be valid for all
> > frames of reference for which the equations of mechanics hold good.
> > 2-1. The laws by which the states of physical systems undergo changes
> > are not affected, whether these changes of state be referred to the
> > one or the other of two systems of co-ordinates in uniform translatory
> > motion.
>
> > I prefer the first 0-1version. Surely you prefer the 2-1 one.
>
> > RVHG (Rafael Valls Hidalgo-Gato

RVHG (Rafael Valls Hidalgo-Gato)
From: PD on 21 Jul 2010 16:50
On Jul 21, 3:33 pm, va...(a)icmf.inf.cu wrote:
> On 21 jul, 08:27, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Jul 21, 8:13 am, va...(a)icmf.inf.cu wrote:
>
> > > On 20 jul, 16:54, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > On Jul 20, 2:37 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > On 20 jul, 10:19, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > > On Jul 19, 6:03 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > > > On 19 jul, 15:20, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > > > > On Jul 19, 2:17 pm, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > On 19 jul, 08:36, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > > > > On Jul 19, 3:35 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > > > On 16 jul, 16:39, "Dono." <sa...(a)comcast.net> wrote:
>
> > > > > > > > > > > > On Jul 16, 11:31 am, va...(a)icmf.inf.cu wrote:
>
> > > > > > > > > > > > > > > > Old fart, Tycho Brache already did that hundreds of years ago.
>
> > > > > > > > > > > > > > > The ECI is a centre of mass inertial frame, in both the Newtonian view
> > > > > > > > > > > > > > > and the 1905 Relativity one, in both holding good the Newtonian
> > > > > > > > > > > > > > > mechanical laws. And you must know that it is absolutely impossible to
> > > > > > > > > > > > > > > describe a Sun moving with respect to an Earth at rest following
> > > > > > > > > > > > > > > Newton’s laws (Tycho Brahe’s work precedes Newton’s one).
>
> > > > > > > > > > > > > > You are an imbecile, old fart.
>
> > > > > > > > > > > > > > > To describe
> > > > > > > > > > > > > > > the Sun’s trajectory you need to consider the Galaxy centre of mass
> > > > > > > > > > > > > > > inertial frame (or maybe a greater one),
>
> > > > > > > > > > > > > > No, old fart. You can use ANY frame. This is the whole point of
> > > > > > > > > > > > > > relativity.
>
> > > > > > > > > > > > > If you insist, describe then the Sun's trajectory in the ECI.
>
> > > > > > > > > > > > Old fart, Tycho Brahe already did this almost 600 years ago. How dense
> > > > > > > > > > > > are you?
>
> > > > > > > > > > > We are talking here about inertial frames, the ones denoted by 1905
> > > > > > > > > > > Einstein stationary systems, in which the equations of Newtonian
> > > > > > > > > > > mechanics hold good. I insist, describe the Sun's trajectory in the
> > > > > > > > > > > ECI using Newton's laws.
>
> > > > > > > > > > Imbecile, Tycho Brahe already showed how this can be done 600 years
> > > > > > > > > > ago. See here :http://www.mathpages.com/rr/s8-01/8-01.htm
>
> > > > > > > > > Incredible! Tycho Brahe using Newton's laws. Surely he made a time
> > > > > > > > > travel.
>
> > > > > > > > I'm sorry, I don't understand. One can describe a trajectory by either
> > > > > > > > detailed observation or by theoretical prediction, and in fact one
> > > > > > > > should have both and compare them to see if the theory is any good.
> > > > > > > > But Brahe's data are quite good descriptions of the trajectories.
>
> > > > > > > > Are you claiming that Newton's laws cannot describe motion from a
> > > > > > > > center-of-mass coordinate?
>
> > > > > > > By the contrary, what I am claiming is that in 1905 Relativity the
> > > > > > > unique inertial frames are the centre of mass ones, and they are
> > > > > > > precisely the stationary systems in which Newtonian equations hold
> > > > > > > good.
>
> > > > > > I'm sorry but this is not correct. I've already mentioned this.
> > > > > > Taking an ordinary example, you can look at the collision of a cue
> > > > > > ball with a set of billiard balls on a table. You may take, for
> > > > > > example, the laws of conservation of energy and momentum as relevant
> > > > > > laws of physics. You can verify that those laws hold in the frame
> > > > > > where the center of mass of this system of balls is at rest, and you
> > > > > > can also verify that these laws hold in the frame where the center of
> > > > > > mass of this system has constant velocity in any direction and in any
> > > > > > amount. It is this set of frames (and there is an infinite number of
> > > > > > them) in which the laws of mechanics hold, and it is this set of
> > > > > > frames that are the inertial ones.
>
> > > > > > If you've not been through this simple exercise in freshman mechanics,
> > > > > > then you were poorly served in your education.
>
> > > > > When you select some body set to consider its centre of mass inertial
> > > > > frame, you are making a model of some part of Nature. There exist here
> > > > > some implicit assumptions. One of them is that you consider all the
> > > > > bodies in the set modelled by a material point (to be able to compute
> > > > > the position of the centre of mass from the positions of the bodies).
> > > > > Another one is to consider the body set the whole Universe, in the
> > > > > model doesn’t exist any other body (for example, when 1913 N.Bohr made
> > > > > his H atom model, he considers an electron and a proton as the unique
> > > > > bodies in the Universe). The fact is that the existence of any other
> > > > > body alters the position of the centre of mass, and there exist a
> > > > > unique centre of mass system for any determined starting body set..
>
> > > > OK, let's stop right there and please reread again what I said. I am
> > > > looking at a FIXED (16 ball) set of objects. The laws of conservation
> > > > of momentum and energy describe the behavior of this system in a
> > > > particular inertial reference frame, that where the center of mass of
> > > > the system is stationary. However, the SAME laws of conservation of
> > > > momentum and energy describe the behavior of this SAME system in any
> > > > other reference frame that where the center of mass of this SAME
> > > > system is moving at constant velocity with any magnitude and any
> > > > direction. That statement is what the principle of relativity is
> > > > about.
>
> > > > I am not adding any other bodies to the system, nor am I considering
> > > > the entire universe to be the system.
>
> > > Of course that you implicitly is considering the 16 balls the entire
> > > universe, when you don’t take into account the mass of other bodies
> > > when determining the centre of mass.
>
> > No. Perhaps you don't understand the meaning of "system" in physics.
> > You can draw an imaginary surface around any collection of objects and
> > that is a system in physics. Some systems can be (for the purposes of
> > the analysis at hand) be considered isolated and others not isolated.
> > Conservation of momentum and conservation of energy are statements
> > about such systems.
>
> > This in no way presumes that the system is the entire universe.
>
> When you have a center of mass inertial system, you can use it only to
> describe the bodies taking into account when determining that centre
> of mass. In your 16 balls system, you can’t use it for example to
> describe an added 17 ball, because the presence of the new ball
> changes the centre of mass.

I'm not talking about adding a 17th ball. I'm talking about the fact
that the laws of physics are the same in any frame in which the center
of mass of the 16 balls has a nonzero constant velocity. There are an
infinite number of such frames.

> The description of the new ball can’t be
> done without a violation of Newton’s laws, your now 17 balls system is
> not an inertial system if you pretend to consider at rest the old
> centre of mass. Then, when using any centre of mass inertial frame,
> there exist always the implicit assumption that the bodies taking into
> account to determine the centre of mass is the entire  universe
> (without any other body in its exterior). This is simple freshman
> physics, for any body set there exists a unique center of mass
> inertial system corresponding to it.> There is a reason why I asked you to consider this example, rather
> > than your favorite planetary system examples. I'd like for you do
> > understand what these concepts mean in ordinary, everyday applications
> > such as is found in a freshman physics text.
>
> > I understand now that you haven't yet gotten a grasp of basic concepts
> > from freshman physics.
>
> The Physics laws are the same in all inertial systems, no matter if
> you are considering balls, planets or any other kind of objects. I
> can’t understand your objection. The GPS is precisely the best example
> of an ordinary, everyday application. Very much useful than the ones
> you can find in a freshman physics text to understand basic physics
> concepts, because it refers to something real that is in a continuous
> function with huge experimental evidence. In it is applied Newtonian
> mechanics, Special Relativity and General Relativity, a wonderful mix
> covering all the spectrum of today physics concepts with the most
> exact and accurate physical measurements, ideal for our purposes here.
> Maybe you don’t know what the Global Positioning System (GPS) is? If
> not, I apologize you in advance for assuming your knowledge of it.
> Whatever the case, you can consider that all what I say about the ECI
> is also about your 16 balls system.
>
>
>
>
>
> > > Let me substitute your example
> > > for the ECI to have at hand its huge experimental evidence. When in
> > > the GPS ECI the centre of mass is determined, even the Moon is
> > > considered not existing, and of course, that centre is considered at
> > > rest. You argue that this centre of mass can be considered moving with
> > > any  uniform velocity (with respect to what?). This implies the re-
> > > introduction of the imaginary (not related with bodies) inertial
> > > frames already put out by 1905 Einstein. Implicitly you are supposing
> > > the ECI the absolute frame, changing then to a relative and apparent
> > > inertial frame (using Newton’s denotations). What can be the purpose
> > > of that change? Absolutely nothing. All the useful information is
> > > already contained in the bodies belonging to the selected body set.
> > > The added uniform velocity (with respect to nothing) is like the
> > > introduction of a strange root when solving an equation. To put it in
> > > the model is absurd, it represents nothing in the real world (by the
> > > way, being imaginary the new frame introduced, it is absolutely
> > > impossible to make any real measurement in or on it -no real bodies
> > > related with it-, allowing to its fans maintain endless discussions in
> > > this group about its existence). But if now you want to consider the
> > > relation of the ECI with its- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -...
>
> read more »

From: valls on 21 Jul 2010 18:29
On 21 jul, 15:50, PD <thedraperfam...(a)gmail.com> wrote:
> On Jul 21, 3:33 pm, va...(a)icmf.inf.cu wrote:
>
> > On 21 jul, 08:27, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Jul 21, 8:13 am, va...(a)icmf.inf.cu wrote:
>
............
>
> > > No. Perhaps you don't understand the meaning of "system" in physics.
> > > You can draw an imaginary surface around any collection of objects and
> > > that is a system in physics. Some systems can be (for the purposes of
> > > the analysis at hand) be considered isolated and others not isolated.
> > > Conservation of momentum and conservation of energy are statements
> > > about such systems.
>
> > > This in no way presumes that the system is the entire universe.
>
> > When you have a center of mass inertial system, you can use it only to
> > describe the bodies taking into account when determining that centre
> > of mass. In your 16 balls system, you can’t use it for example to
> > describe an added 17 ball, because the presence of the new ball
> > changes the centre of mass.
>
> I'm not talking about adding a 17th ball. I'm talking about the fact
> that the laws of physics are the same in any frame in which the center
> of mass of the 16 balls has a nonzero constant velocity. There are an
> infinite number of such frames.
I added a new body with the purpose to explain you the implicit
assumption in any center of mass inertial system about being its body
set the entire universe. Taking for granted that you understand it
already, I return to your original 16 balls center of mass inertial
frame. Now you want to put it with a non-zero uniform velocity. OK, a
single question. In the model, with respect to what you pretend to put
the entire universe moving with a non-zero uniform velocity? Only in
the Newtonian mechanics (with absolute frame) you can do that, never
in 1905 Relativity (without absolute frame).

RVHG (Rafael Valls Hidalgo-Gato)
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