Prev: NYT - 7/13/10 - "Gravity Does Not Exist", but pseudoscience rules
Next: Physics Turned Upside Down to Keep the Hour Glass of Time Flowing
From: PD on 22 Jul 2010 15:06
On Jul 22, 11:15 am, va...(a)icmf.inf.cu wrote:
> On 21 jul, 17:55, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Jul 21, 5:29 pm, va...(a)icmf.inf.cu wrote:
>
> > > 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.
>
> > First of all, let's get the language right.
> > The 16 balls is a *system*. It is not the entire universe. It is a
> > physical *system*.
> > Secondly, there is a frame of reference which is NOT the system, in
> > which the center of mass of this system is at rest. This you can call
> > "the center of mass frame" of this system if you like.
>
> I don’t call anything, I am not the one introducing the centre of mass
> inertial frame concept, it is already in Newtonian mechanics long
> before 1905 Einstein. Yes, you can call the body set (your 16 balls) a
> physical system, a closed one where you can apply conservation laws.

Or even an open one, if you like, where work, heat and impulse can
cross the boundary of the system. Note you do not have to pretend that
objects outside the system do not exist.

> If you want now to consider the centre of mass inertial system
> corresponding to that physical system, in the model exists the
> implicit assumption that the physical system is the entire universe.

Not at all.

> I
> explained in detail all this already to you, but you seem not
> understand it yet. I will try again.
> When the position of the centre of mass relative to the body set is
> determined, ONLY the 16 balls are taking into account, you are
> assuming then in the model that they are the unique existing bodies
> (that they are the entire universe).

Not at all. A center of mass of a SYSTEM is a property of the objects
IN THAT SYSTEM, *regardless* of what lies outside it. You certainly do
not have to assume that there is nothing outside the system to find
the center of mass of a system.

> This is nothing new in Physics,
> when 1913 Bohr develops its H atom model, he consider a universe with
> only a proton and an electron, determining their centre of mass at
> rest. Corresponding to any body set exists a unique centre of mass
> inertial frame. You must consider always the exterior of the physical
> system empty, putting a single body there alters the centre of mass (I
> introduced the ball 17 with that purpose).
>
> > Now, what I said is that the laws of physics governing this *system*
> > are identical also in any other reference frame in which the center of
> > mass of this system is moving with constant velocity.
>
> We are in agreement about the laws of physics being the same in all
> inertial frames. What you don’t understand yet is that to have a
> centre of mass moving with a non-zero uniform velocity you need the
> Newtonian absolute inertial frame already put out by 1905 Einstein.

And this is plainly wrong.
As I explained to you, you can consider the behavior of this system
according to the same laws of physics in any of an INFINITE number of
reference frames, in each of which the center of mass of the system is
moving with constant velocity. This choice is completely arbitrary and
can be done differently by different people thinking about the same
system. This cannot possibly mean that those people are thinking about
different universes. There is only one universe.

> The entire universe can be moving only in the absolute frame.> Note that I am not involving the entire universe in ANY of this.
>
> False. Once you talk about a centre of mass inertial frame, in the
> model the body set (or physical system) is already considered the
> entire universe, as I explained in detail to you already twice.

But you're wrong. A system is not the universe.

> I have a system of 16 balls.
> > This system has a center of mass.
>
> Then, in your model the 16 balls have no other body in its exterior,

And that's patently absurd. You have no idea what a system is in
physics. You probably need to revisit freshman physics where this is
defined clearly.

> because its presence alters the centre of mass (not exist a 17 ball or
> any other body).> I can look at the coordinates of the center of mass of this system in
> > a reference frame.
>
> In 1905 Relativity that reference frame must be the centre of mass
> inertial frame corresponding to your body set. You can’t have never
> two different inertial frames derived from the same body set. And only
> in the Newtonian view you can have inertial frames independent from
> bodies.> In one particular reference frame, the coordinates of the center of
> > mass of this system is constant -- the center of mass is stationary.
> > In any other inertial reference frame, the coordinates of the center
> > of mass of this system is moving with constant velocity.
>
> For a non-zero uniform velocity, only in the Newtonian view with
> absolute frame, never in the 1905 Relativity one without absolute
> frame. 1905 Einstein never  “assign a velocity-vector to a point of
> empty space in which electromagnetic processes take place” (in the
> Introduction of the 30Jun1905 paper). Inertial frames are denoted by
> him stationary systems.
>
> Nothing more good to understand anything that to analyse a real
> example in our world. Consider the GPS ECI. The body set (physical
> system) corresponding to the ECI is only our real Earth and some
> satellites and atomic clocks in them (even the Moon is considered not
> existing in the model). Corresponding to that body set a unique centre
> of mass inertial frame is derived, denoted ECI (Earth Centred Inertial
> system). The rotation of the Earth, the orbit of the satellites, the
> clocks at the Earth surface, absolutely all relevant things that moves
> is described in the same unique inertial frame. And the centre of mass
> of it is considered at REST, and the delay on all clocks owed to
> velocity correspond exactly to the one predicted by the 1905
> Relativity formula (the same one used by 1905 Einstein in his example
> at the end of paragraph 4 of his 30Jun1905 paper, precisely having as
> the stationary system the same today denoted ECI!). All of this with a
> huge experimental evidence.
> But the centre of the Earth is NOT at rest, anybody knows that it is
> moving with a gravitational centripetal acceleration around the Sun!
> (could say you). And you are right, but that view corresponds to a
> different body set, the Solar System one, with a different centre of
> mass inertial frame (with centre considered also at REST!). In the
> previous case I added the 17 ball to obtain a new centre of mass
> inertial frame, in this case I added to the Earth all the rest of the
> Solar System.
> The ECI and the Solar System are examples of what I denote (many years
> ago) a Hierarchical Inertial System (HIS). The ECI is part of the
> Solar System, low hierarchy HIS compose high hierarchy ones. 1905
> Relativity lead us to a hierarchical view of our Universe. HIS (1905
> Relativity stationary systems, inertial frames) are equivalent in the
> sense of the same Physics laws, but hierarchical in the sense of the
> entities described in it.
>
>
>
> > >  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)- Hide quoted text -
>
> RVHG (Rafael Valls Hidalgo-Gato)- Hide quoted text -
>
> - Show quoted text -

From: PD on 22 Jul 2010 17:20
On Jul 22, 11:15 am, va...(a)icmf.inf.cu wrote:

> When the position of the centre of mass relative to the body set is
> determined, ONLY the 16 balls are taking into account, you are
> assuming then in the model that they are the unique existing bodies
> (that they are the entire universe).

To try to explain this further, you worry about the presence of a 17th
ball outside the system that would affect the center of mass. It does
NOT affect the center of mass of the system, because the SYSTEM
specified contains the 16 balls, not the 17th ball. The center of mass
is calculated using only those masses IN THE system, not all the
masses available everywhere. The presence of the 17th mass outside the
system in no way affects the center of mass of the system of 16 balls.
From: valls on 22 Jul 2010 19:01
On 22 jul, 10:57, harald <h...(a)swissonline.ch> wrote:
> On Jul 22, 12:55 am, va...(a)icmf.inf.cu wrote:> On 20 jul, 08:58, harald <h...(a)swissonline.ch> wrote:
>
> > > On Jul 20, 1:24 pm, va...(a)icmf.inf.cu wrote:
>
> [..]
>
> Last remarks:
>
> > > > In the Introduction of his 30Jun1905 paper, 1905 Einstein put out very
> > > > clearly the Newtonian absolute inertial frame (and then
> > > > also any other thing derived from it).
>
> > > No, he merely did not *include* it and like everyone else
> > > before him he *kept* everything that was derived from it.
>
> > If that is true, then we must put out from 1905 Relativity all the
> > things derived from the ones it excludes, in order to maintain a
> > coherent interpretation. I really don’t think that 1905
> > Einstein does that.
>
> Clearly HE did not, but his mechanics teachers DID keep in mechanics
> all the things derived from the cause they omitted (just as my
> classical mechanics textbooks did). He simply took that for granted.
>
This is precisely the cause for me to distinguish 1905 Relativity from
the today Special Relativity. I don’t care at all about what
Einstein’s teachers did, specially 1907 Minkowski, that clearly re-
introduces in the theory all Newtonian inertial frames without
relation at all with massive bodies. Yes, the after 1905 Einstein
forgets completely his rigid massive bodies (including the rigid
material lines) from which he builds the original theory, not talking
more about them.
A precision, you say first that 1905 Einstein “not *include*” the
absolute frame, now you use the word “omitted”, not being clear for me
if you are referring to 1905 Einstein or his teachers. Whatever the
case, what I am taken for granted is that 1905 Einstein make the
EXCLUSION of the absolute frame, because without any doubt the
absolute frame is already present in the 1905 Physics as a fundamental
concept for the Newtonian mechanics and also for the 1905 Maxwell
electrodynamics. 1905 Einstein takes an active decision putting out
the absolute frame.

> > Whatever the case, I will follow the behaviour expressed.> The text is the following:
>
> > > > [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, nor
> > > > assign a velocity-vector to a point of the empty space in
> > > > which electromagnetic processes take place.]
>
> > > Originally "insofar as" was emphasized - as you now know!
> > > Don't you understand the meaning of that word? Don't you
> > > understand the words "do not require", and "nor assign"?
>
> > Unfortunately English is not my mother language, my understanding of
> > something can’t depend on single words or even short phrases. I
> > am still searching for what  “insofar” means.
>
> It means that it is not an absolute statement, but merely related to
> the points he next mentions. Freely translated in other words:
>
> He did not need to introduce a "luminiferous ether" model with special
> properties such as a determined velocity because in his theory no
> frame has special properties that make it distinguishable from others
> by a velocity effect.
>
But he also says (in the following text not addressed by you now) that
he not “assign a velocity-vector to a point of the empty space in
which electromagnetic processes take place”, suggesting me now that he
never consider a light ray in a moving frame. By the way, I remember
now that in his second version of the second postulate (at the
beginning of paragraph 2) he postulates light moving with velocity c
only in the stationary system. In his first version (of the second
postulate in the introduction) he only refers c as the light velocity
in empty space. Making an overall view with all this information, it
seems to me that 1905 Einstein stationary system denotation is
something more than a verbal one (as he says). All seem pointing to a
stationary system (inertial frame) always considered at rest (an then
not possible to distinguish from other ones for a velocity effect),
but perfectly distinguishable by its always different body set. This
is not precisely the way men reach the knowledge about our rotating
and moving Earth as part of the Solar System, also moving in the
Galaxy? Very different to Galileo’s ship with all windows closed, men
have always the eyes looking for the whole Universe.
> > I consider the essential
> > point of the referred text the exclusion of the Newtonian
> > absolute frame, fortunately already confirmed by you.
>
> I did no such thing; see below.
>
This is a very great surprise for me now. I am taking for granted that
1905 Einstein EXCLUDES the absolute frame from his new theory. Take a
little of patience and explain to me (when you want) how can you
conceive an inertial frame (totally empty, without any relation at all
with massive bodies) in the 1905 Relativity based on rigid massive
bodies. Don’t forget that I consider all 1905 Einstein’s teachers
opinions without relation at all with 1905 Relativity (including also
with them all after 1905 Einstein’s opinions!).
> > > If you don’t have already empty inertial frames (not related with
> > > > massive bodies) moving with absolute uniform velocities (“nor assign a
> > > > velocity-vector to a point of empty space”), what remains to determine
> > > > inertial frames?
>
> > > He explained that in the *same* paragraph - as he likely was taught:
>
> > > "all frames of reference for which the equations of mechanics
> > > hold good."
>
> > From that I interpret that 1905 Einstein is referring to the inertial
> > frames compatible with the exclusion of the absolute inertial
> > frame (and all the consequences derived from that fact).
>
> That's a self-contradictory interpretation!
> In an "absolute" inertial frame the equations of mechanics certainly
> hold good. Consequently an "absolute" inertial frame is included if it
> exists (which question he did not discuss).
>
The phrase where you are supporting your assertion (“all frames of
reference for which the equation of mechanics hold good”) is part of
the first version of the 1905 Einstein Principle of Relativity (1905
PoR). The full text is in the introduction (between [ ]):

[The same laws of electrodynamics and optics will be valid for “all
frames of reference for which the equation of mechanics hold good”]

In the historic 1905 context, the laws of electrodynamics and optics
are valid ONLY in the absolute frame (light is considered an
electromagnetic wave on the ether). And the equations of mechanics are
valid in ALL frames, the absolute one and the relative ones. Then,
that the laws of both types are valid in the absolute frame is a known
fact in 1905. You pretend know to derive from this 1905 known fact,
that an inertial frame can be the absolute one (if it exists) in 1905
Relativity. But you forget totally that in 1905 Relativity, the
holding of the equations of mechanics is NOT the unique requisite for
an inertial frame to be included in 1905 Relativity. Fortunately the
relevant 1905 text is a continuous writing, the end of the
introduction and the beginning of paragraph 1. Let me put it
integrally (between [ ]):

[ The theory to be developed is based –like all electrodynamics- on
the kinematics of the rigid body, since the assertions of any such
theory have to do with the relationships between rigid bodies (systems
of co-ordinates), clocks and electromagnetic processes. Insufficient
consideration of this circumstance lies the root of the difficulties
which the electrodynamics of moving bodies at present encounters.
I.KINEMATICAL PART
1. Definition of Simultaneity
Let us take a system of co-ordinates in which the equations of
Newtonian mechanics hold good. In order to render our presentation
more precise and to distinguish this system of co-ordinates from
others which will be introduced hereafter, we call it the “stationary
system”. ]

As you see, 1905 Einstein identify first rigid bodies with systems of
co-ordinates (rigid material lines at the beginning of paragraph 3),
and later denotes stationary the systems of co-ordinates in which the
equations of Newtonian mechanics hold good (inertial frames). The
relationship between inertial frames and bodies is established very
clearly, does not exist here any place for the absolute frame not
related at all with any body, no matter if it exist or not.

> However, instead of using a frame that cannot be determined for the
> theory, any inertial frame may be taken for the operational
> definitions of the theory.
>
Sorry, again false. As we address in the past comment, ALL inertial
frames are already determined in the theory as the ones related with
bodies. And the unique inertial frames related with bodies already
present in the Newtonian mechanics before 1905 Einstein are the centre
of mass ones.
> In short: if I don't introduce chocolate or angels in a discussion
> because I don't have use for them in that discussion, I am *not*
> negating the existence of chocolate or angels!!
>
The important point for me here is not the existence or not of the
absolute frame, but its exclusion from 1905 Relativity whatever the
case.
> [..]
>
> Bye,
> Harald
Best regards,

RVHG (Rafael Valls Hidalgo-Gato)
From: Inertial on 22 Jul 2010 19:30
wrote in message
news:b6c4ba7b-2c80-49cf-86fe-4be5a389e4f4(a)c10g2000yqi.googlegroups.com...
>This is precisely the cause for me to distinguish 1905 Relativity from
>the today Special Relativity. I don�t care at all about what
>Einstein�s teachers did, specially 1907 Minkowski, that clearly re-
>introduces in the theory all Newtonian inertial frames without
>>elation at all with massive bodies.


WRONG. They were not RE-introduced,. because they were NEVER EVER REMOVED.
Your clams that they were are unfounded lies .. nothing more.


From: Inertial on 22 Jul 2010 19:44
"PD" wrote in message
news:be9babb8-7f7b-4600-95c8-c7c7433ada65(a)w30g2000yqw.googlegroups.com...
>On Jul 22, 11:15 am, va...(a)icmf.inf.cu wrote:
>> When the position of the centre of mass relative to the body set is
>> determined, ONLY the 16 balls are taking into account, you are
>> assuming then in the model that they are the unique existing bodies
>> (that they are the entire universe).
>
>To try to explain this further, you worry about the presence of a 17th
>ball outside the system that would affect the center of mass. It does
>NOT affect the center of mass of the system, because the SYSTEM
>specified contains the 16 balls, not the 17th ball. The center of mass
>is calculated using only those masses IN THE system, not all the
>masses available everywhere. The presence of the 17th mass outside the
>system in no way affects the center of mass of the system of 16 balls.

It sounds like he is advocating the centre-of-mass-of-the-universe as a
special (absolute) frame.

First  |  Prev  |  Next  |  Last
Pages: 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Prev: NYT - 7/13/10 - "Gravity Does Not Exist", but pseudoscience rules
Next: Physics Turned Upside Down to Keep the Hour Glass of Time Flowing