(Randy Poe) wrote in message om...
(Patrick Reany) wrote in message . com...
You're claiming that a frame of reference of not a piece of matter?

If I say "the frame of reference of the earth's surface" (a
rotating frame), what piece of matter is that?

Did you think that I wouldn't have a ready answer to all this? Let's
do it.

You can't see that the earth's surface (a layer of material particles)
can be used for *locally* setting out coordinates? Look at a football
field. Look at a ruler afixed to the bench of a physics laboratory
table. However, the expression "the frame of reference of the earth's
surface" itself is ambiguous. But one can always -- in principle --
setup a local grid about any point on the earth's surface. You just
like to ask ambiguous questions. My point is that once one stops asks
ambiguous questions about using matter to setup a frame of reference,
then setting up such a frame is usually easy to do, given that one is
not in some exotic environment, which you'll get to below.



If I say "the frame of reference of the earth's center of
mass" (a non-rotating frame), what piece of matter is that?

Although the earth's center of mass could be approximated by some
particle down there, that misses the point. The center of the earth is
by definiton a point and hence cannot be a piece (or chunk) of matter
used to assign spacio-temporal coordinates to things or events. Since
the width of a point is zero, the only lengths that could be made by
use of a point are things that have length zero. This isn't rocket
science here.

To setup a real frame of reference one has to have a chunk of matter
to do so. A ruler is a chunk of matter; a physics lab is a chunk of
matter. If you have a ruler of length zero, you can only use it to
measure things of length zero!

Now, what about frames of reference which are hypothetically
"attached" to exotic objects, such as electrons, or in exotic places,
such as inside the sun? Well, first note that such "frames" are
hypothetical. Of course physics has to be allowed to make hypothetical
frames but it is a weakness, because there is no direct way to
physically test if the hypothetical model is working right in the
theory. All one can do is to proceed with caution; if experiement
matches prediction based on this hypotheical model, then so far so
good; otherwise, a new model of such a frame may have to be made.

Hypothetical frames are needed, but they're also problematic. Real
frames are always made out of "visible" matter. Hypothetical frames
are modeled as if one could place a chunk of visible matter in some
place. Finally, this notion of visible is meant to provide direct
physical contact and testability. It does not mean a restriction to
visible light -- that which the unaided human eye uses, because we can
use other frequencies to "see" by. It does not even mean restricted to
"seeing" by EM radiation at all. After all, bats can "see" using
sound.



For that matter, if I talk about two frames of reference
relative to ME, but rotating at different rates, those
are clearly different frames of reference. What piece
of matter are you associating with each one?

Well, you haven't operationally defined what you're talking about once
again. So, I'll have to set it up for you. Take two disks of matter
(thin but not infinitely thin), one at rest relative to the earth's
surface and parallel to it, and you standing on the center point of
the disk. And the other suspended above the first and you, in a plane
parallel to the first, and rotating about its vertical axis through
its center. Both disks, then, are potential frames of reference. They
can be made into actual frames of reference, say, by have polar
"coordinate systems" scratched onto their surfaces to any degree of
closeness that one would like, to within practicality, and then one
could assign approximate position coordinates as function of time to
any particle sufficiently close to these surfaces to be able to claim
event status.



If I say "the frame of the cosmic background", what piece of
matter is that?


Your statement is ambiguous to me once again. Let's deal with this
issue once and for all: There is no such thing as a "natural" frame
associated to any chunk of matter. To turn a chunk of matter into a
frame, one has to choose axes and a unit of measure along these axes.
Now, the cosmos is itself a chunk of matter -- we just happen to sit
inside this Big Chunk. Astronomers can setup a local coordinate system
of the solar system by choosing axes by incorporating stars among the
fixed stars. And the unit of measure? I seem to remember that
astronomers adopted the so-called Astronomical Unit -- the average
distance from the sun to the earth, a distance defined by two bits of
the Big Chunk of the cosmos.

I'm not familiar with the expression "the frame of the cosmic
background," so I don't know what to make of it. If it means the CMBR
then I personally don't know how to make that into a frame of
reference -- perhaps a cosmologist does though. But if it means a
frame built out of stars and the like, then I see no problem in
principle in making some kind of reference system out of it. It's
doable so long as one can meaningfully use some of this cosmic matter
set up axes so then to use to make judgments of the distances of some
other piece of matter of the cosmos from those axes.

Patrick

(Randy Poe) wrote in message . com...
(Patrick Reany) wrote in message . com...
(Randy Poe) wrote in message . com...
(Patrick Reany) wrote in message . com...
Did SR invent the concept of 'frame of reference'?

What difference does it make if the idea was introduced
with SR? It's more general than that and makes perfectly
good sense in Galilean relativity too.

First, what is a "frame of reference"? A "frame of reference" is an
aggregation of matter

Oops.

(usually nearly "rigid" in the Euclidean sense,

Oops.

Nope. A frame of reference is a coordinate system.

You're claiming that a frame of reference of not a piece of matter?

Yes.

A coordinate system may be fixed relative to some "piece of
matter". But it is not a piece of matter.

I've already gone over this distiction between "coordinate system" and
"frame of reference."


Yes.

A coordinate system"


I suppose I know what you're thinking in your muddled way.
For instance, I might define the earth-moon-centered frame
of reference. This is a coordinate system which is located
at the center of mass of the earth-moon system.

Now in your murky depths, you're thinking (and probably going
to reply) "aha! it's defined in terms of the earth and moon
and those have mass". That's true. It's defined in terms
of two large massive objects.

How do you define the directions of your axes of your coordinate
system and a unit of measure without employing matter to do so?

As for this ridiculous red herring of mass, I'll say this: The essense
of a ruler is it ability to remain a rigid chunk of matter through
time. Yes, the ruler has mass because it's made of matter, but the
actual mass is not typically relevant, except to the guy who has to
carry it around. A one-meter ruler made of wood can be just as good
for measuring as a one-meter ruler made of depleted uranium, though
they weigh in as different.

You keep missing the fundamental point. The main reason that real
frames of reference are made of matter is because of the fundamental
goal of physics, which is to discover the smallest set of rules by
which the behavior of the inanimate material world, acting under
natural conditions, can be predicted. Measuring instruments are part
of the natural material world, and as such have to have their own
behaviors explicitly accounted for by the theories of physics!
Abstract coordinate systems are not empirically subject to the
theories of physics. But once those abstract coordinate systems are
attached to a chunk of matter, the resulting frames of reference are
accountable to the theories of physics. This is all related to what is
meant by an operationally defined variable of physics.



But the reference frame doesn't have any mass. What is
its mass?

If the frame of reference is just used in a kinematical theory, it
makes no difference what its mass is. But if the frame of reference is
*also* used as an object in a dynamical theory, then -- and ONLY then
-- is its mass important. You keep mixing up different concepts
because you keep ignoring all these distinctions.


If you and I are sitting still relative to each other, what
is the mass of our reference frame?

What frame of reference? You haven't defined what this frame of
reference is. Once again I tell you: there is no such thing as a
"natural" frame of reference. You have to explicitly setup such a
thing. Wooden rulers do NOT just grow on trees for the picking. You
take a piece of wood, cut it to size, decide on a unit measure, mark
off knotches on the wood according to that unit, and presto, then
you've got a ruler! That ruler is a frame of reference for a single
dimension. What is so hard to understand about that? Marking off
knotches along the wood according to a fixed unit is setting up a
crude coordinate system within, or "on," a chunk of matter, and that
is one way to make a frame of reference. The reason to force
coordinate systems to instantiate onto matter, is because real
measuring instruments are made of matter, and those instruments may be
affected by motion or by environmental factors which may affect the
unit of measure and which theory must account for. Now do you get it?

Patrick

Patrick Reany wrote in message
om...
(Randy Poe) wrote in message
. com...
(Patrick Reany) wrote in message
. com...
(Randy Poe) wrote in message
. com...
(Patrick Reany) wrote in message
. com...
Did SR invent the concept of 'frame of reference'?

What difference does it make if the idea was introduced
with SR? It's more general than that and makes perfectly
good sense in Galilean relativity too.

First, what is a "frame of reference"? A "frame of reference" is
an
aggregation of matter

Oops.

(usually nearly "rigid" in the Euclidean sense,

Oops.

Nope. A frame of reference is a coordinate system.

You're claiming that a frame of reference of not a piece of matter?

Yes.

A coordinate system may be fixed relative to some "piece of
matter". But it is not a piece of matter.

I've already gone over this distiction between "coordinate system" and
"frame of reference."


Your own, personal defintion doesn't count. Try Einstein's.

--
greywolf42
ubi dubium ibi libertas
{remove planet for return e-mail}

(Patrick Reany) wrote in message . com...
(Randy Poe) wrote in message . com...
(Patrick Reany) wrote in message . com...
(Randy Poe) wrote in message . com...
(Patrick Reany) wrote in message . com...
Did SR invent the concept of 'frame of reference'?

What difference does it make if the idea was introduced
with SR? It's more general than that and makes perfectly
good sense in Galilean relativity too.

First, what is a "frame of reference"? A "frame of reference" is an
aggregation of matter

Oops.

(usually nearly "rigid" in the Euclidean sense,

Oops.

Nope. A frame of reference is a coordinate system.

You're claiming that a frame of reference of not a piece of matter?

Yes.

A coordinate system may be fixed relative to some "piece of
matter". But it is not a piece of matter.

I've already gone over this distiction between "coordinate system" and
"frame of reference."

As I thought of it I realized that "frame of reference"
should be thought of more generally than coordinate system.
It's more like a family of coordinate systems. There
are infinitely many coordinate systems all within the
same frame of reference. They share a common state
of motion.

I'm not sure where to find a rigorous mathematical (as
opposed to dictionary) definition of "frame of reference".
I can tell you that all coordinate systems within one
common frame of reference share the property that
the transformations between them are independent of
time. But that doesn't capture the GR influence of
massive objects.
Now in your murky depths, you're thinking (and probably going
to reply) "aha! it's defined in terms of the earth and moon
and those have mass". That's true. It's defined in terms
of two large massive objects.

How do you define the directions of your axes of your coordinate
system and a unit of measure without employing matter to do so?

See? You made just the logical fallacy I told you you would.

"Using an object to define a direction" does not mean
"this object IS the coordinate system".

If I define the x-axis as being the line from earth center
to sun center (which changes in time), that does not
mean the earth is an x-axis. Nor is the sun an x-axis.

As for this ridiculous red herring of mass, I'll say this: The essense
of a ruler is it ability to remain a rigid chunk of matter through
time.

No. Rigid chunks of matter make inferior rulers. That's
why the international standards organizations switched
to matter-independent length references in 1983.

You keep missing the fundamental point. The main reason that real
frames of reference are made of matter

I gave some specific examples. Here are two:

1. The frame of reference of the earth's surface, such
as we use for navigation around the earth (driving to
work, flying aircraft, etc). The matter in question is
made up of the entire earth. This frame is rotating
in time, with a period of 23:56.

2. The frame of reference of the center of mass of the
earth, useful for satellite navigation, ballistic
missiles, etc. The matter in question is made up of
the entire earth. This frame is in orbit around the
sun.

Two frames, same matter. If you say "the matter is the
frame, the frame is the matter" then how is it the
same matter can give rise to different frames?

- Randy

(Randy Poe) wrote in message . com...
(Patrick Reany) wrote in message . com...
(Randy Poe) wrote in message . com...
(Patrick Reany) wrote in message . com...
(Randy Poe) wrote in message . com...
(Patrick Reany) wrote in message . com...
Did SR invent the concept of 'frame of reference'?

What difference does it make if the idea was introduced
with SR? It's more general than that and makes perfectly
good sense in Galilean relativity too.

First, what is a "frame of reference"? A "frame of reference" is an
aggregation of matter

Oops.

(usually nearly "rigid" in the Euclidean sense,

Oops.

Nope. A frame of reference is a coordinate system.

You're claiming that a frame of reference of not a piece of matter?

Yes.

A coordinate system may be fixed relative to some "piece of
matter". But it is not a piece of matter.

I've already gone over this distiction between "coordinate system" and
"frame of reference."

As I thought of it I realized that "frame of reference"
should be thought of more generally than coordinate system.
It's more like a family of coordinate systems. There
are infinitely many coordinate systems all within the
same frame of reference. They share a common state
of motion.

I'm not sure where to find a rigorous mathematical (as
opposed to dictionary) definition of "frame of reference".

So do I. Typical lack of caring on the part of the physics community
to cover important issues just because somebody might call them
"philosophical." Fundamental things have to be covered whether they
are "philosophical" or not.

I can tell you that all coordinate systems within one
common frame of reference share the property that
the transformations between them are independent of
time. But that doesn't capture the GR influence of
massive objects.

"Coordinate system" is obviously endowed with more "freedom" than
reference frame. A frame of reference is a chunck of matter which has
been coordinatized with some coordinate sytem. There is a lot of
freedom on how to place a coordinate system on a chunk of matter, just
in how to orient axes alone. Even a ruler has theoretical infinite
choice of the size of its unit measure.


Now in your murky depths, you're thinking (and probably going
to reply) "aha! it's defined in terms of the earth and moon
and those have mass". That's true. It's defined in terms
of two large massive objects.

How do you define the directions of your axes of your coordinate
system and a unit of measure without employing matter to do so?

See? You made just the logical fallacy I told you you would.

"Using an object to define a direction" does not mean
"this object IS the coordinate system".

If I define the x-axis as being the line from earth center
to sun center (which changes in time), that does not
mean the earth is an x-axis. Nor is the sun an x-axis.

As for this ridiculous red herring of mass, I'll say this: The essense
of a ruler is it ability to remain a rigid chunk of matter through
time.

No. Rigid chunks of matter make inferior rulers.

In all cases? It still works fine for me when I want to buy a piece of
wood at the hardware store.

That's
why the international standards organizations switched
to matter-independent length references in 1983.

Whatever it chose, it no doubt involves 1) Matter and 2) physical laws
which take the place of matter rulers. Even a laser beam eminates from
a piece of matter, which itself is fixed to another piece of matter.



You keep missing the fundamental point. The main reason that real
frames of reference are made of matter

I gave some specific examples. Here are two:

1. The frame of reference of the earth's surface, such
as we use for navigation around the earth (driving to
work, flying aircraft, etc). The matter in question is
made up of the entire earth. This frame is rotating
in time, with a period of 23:56.

There is no unique "frame" that is associated with the earth. One may
choose to take all the earth or just a part of it to use as a frame of
reference (local coordinates); it all depends on what purpose you have
in mind. I don't care, myself, to construct a coordinate system on the
entire earth just to get around town. The size of the chunk one wants
is a free choice, so long as it has enough dimension to be useful for
measuring what you want to be measured. But putting the issue of
nonuniqueness aside, I don't get your point.



2. The frame of reference of the center of mass of the
earth, useful for satellite navigation, ballistic
missiles, etc. The matter in question is made up of
the entire earth. This frame is in orbit around the
sun.

Sure, because the earth is in orbit. The minimum amount of matter of
the earth you want to use in your frame depends on what you want to do
with the frame. There is no way to make a real measurement that is
completely independent of matter.


Two frames, same matter. If you say "the matter is the
frame, the frame is the matter" then how is it the
same matter can give rise to different frames?

- Randy

I say that a frame of reference is a coordinatized chunk of matter,
and in no sense need it even be contiguous since we already know that
matter is not contiguous anyway. Now, given the problem of determining
a frame of reference that contains the center of the earth, I have a
lot of choice in doing so. I can included only matter of the earth,
some or all of it. Or I can include the fixed stars if I want. It
depends on what I want to accomplish with this frame. Frames can have
different matter contents yet be completely equivalent for measurement
purposes. Say I am an astronomer who wants to track the path of a
comet on the celestial sphere. I can choose as my frame of reference
all the fixed stars. Or I can arbitrarily choose one star to drop from
this frame. If I do this I will still have sufficient stars to able to
accurately track the comet. The two distinct frames are equivalent for
that purpose.

Your claim that I declared that "the same matter can give rise to
different frames" is beyond me. To make such a claim one would need to
have some relation of comparison on frames of reference, and I don't
remember having provided such a relationship. Let's deal with that.
I'm going to say that once the matter content of a frame is decided,
then any two coordinatizations of that matter such that the resulting
frames have equal abilty to assign spacio-temporal coordinates to all
events within the "measurement vacinnity" (or their "event envelopes"
which is definable independently of coordinate systems) of the matter
are "equivalent." In principle, two coordinatizations always produce
equivalent frames, but the problem comes from the fact that our
coordinatizations are also practical matters of someone placing real
grid lines or equivalent on the chunk of matter. To the degree that
this is done equally for both coordinatizations, the resulting frames
have the same event envelopes.

So, two different frames can differ either by having different
coordinatizations or by having different matter content, yet be
equivalent for measurement purposes.

Patrick

(Patrick Reany) wrote in message
Your statement is ambiguous to me once again. Let's deal with this
issue once and for all: There is no such thing as a "natural" frame
associated to any chunk of matter. To turn a chunk of matter into a
frame, one has to choose axes and a unit of measure along these axes.
Now, the cosmos is itself a chunk of matter -- we just happen to sit
inside this Big Chunk. Astronomers can setup a local coordinate system
of the solar system by choosing axes by incorporating stars among the
fixed stars. And the unit of measure? I seem to remember that
astronomers adopted the so-called Astronomical Unit -- the average
distance from the sun to the earth, a distance defined by two bits of
the Big Chunk of the cosmos.


The whole development of the relativistic system was the seeming
removal of 'absolute time' and 'absolute space' which can be directly
attributed to the scholium iv of the Principia.

Newton did not wish to call observation of the motion of the primary
planets as viewed from Earth an 'illusion' insofar as the motions are
valid up to a point but are ultimately translated into heliocentric
modelling,instead of calling it an illusion he called it 'relative
space'.Absolute space is the actual motions we are partaking in
without experiencing it,the bridge between relative space and absolute
space are the models,it may be archaic phrasing on Newton's part and
he is not always correct but as you lot close your eyes and pretend
not to see the purpose and intents of what Newton considered absolute
and relative you are hardly likely to know the destruction you cause.

The first principle of any investigation into any physical phenomena
is that the Earth rotates in 24 hours through 360 degrees,Albert
violates this basic premise by determining stellar circumpolar motion
describes a circle in 24 hours (astronomical 24 hour day)

"The visible fixed stars are bodies for which the law of inertia
certainly holds to a high degree of approximation. Now if we use a
system of co-ordinates which is rigidly attached to the earth, then,
relative to this system, every fixed star describes a circle of
immense radius in the course of an astronomical day, a result which is
opposed to the statement of the law of inertia"

http://www.bartleby.com/173/4.html

He may as well have said the amount of cars on pasta is opposed to the
price of tea in China,the basic premise is wrong but he goes on to
build a geometric system based on it.He is a siderealist,a strange
mixture of a geocentrist and a heliocentrist,a mixture so bad that
even the creationists look sensible.

Because he adopted the sidereal value for the rotation of the Earth
his models which reflect that value (the correct interpretation is
that the Earth rotates in 24 hour through 360 degrees and this then
determines the sidereal stellar circumpolar value).With a constant
orbital displacement with each axial rotation and a fictitous meridian
alignment with the Sun in 24 hours,Albert is definitely Aristotlian in
his outlook as are all his followers.

http://www.astro.ufl.edu/~oliver/ast...Ntime/time.htm

http://www.kepler.arc.nasa.gov/johannes.html






I'm not familiar with the expression "the frame of the cosmic
background," so I don't know what to make of it. If it means the CMBR
then I personally don't know how to make that into a frame of
reference -- perhaps a cosmologist does though. But if it means a
frame built out of stars and the like, then I see no problem in
principle in making some kind of reference system out of it. It's
doable so long as one can meaningfully use some of this cosmic matter
set up axes so then to use to make judgments of the distances of some
other piece of matter of the cosmos from those axes.

Patrick

What an utterly stupid thing to do,people who cannot recognise that
Albert ignored the most basic observation possible,that you cannot
directly link the rotation of the Earth through 360 degrees to the 23
hours 56 min,so Patrick,your frames of reference are all wrong and
will never be right.Relativists may be the dumbest people ever to set
foot on the planet,it requires that a new term be applied to the
quasi-geocentricity that Albert dumped on and mathematicians
accepted,it is called siderealism and is comparable only with
creationism.

(Oriel36) wrote in message . com...
The first principle of any investigation into any physical phenomena
is that the Earth rotates in 24 hours through 360 degrees,Albert
violates this basic premise by determining stellar circumpolar motion
describes a circle in 24 hours (astronomical 24 hour day)

You never did explain how I can rotate 360 degrees, move
partway around an orbit, and still be facing the center.

Paint a circle on the ground. Stand on the circle,
facing the center. Rotate exactly 360 degrees.
You are again facing the center. Now, without
changing orientation, step one pace
to the right. Are you still facing the center?

- Randy

"Randy Poe" wrote in message
om...
(Oriel36) wrote in message
. com...
The first principle of any investigation into any physical phenomena
is that the Earth rotates in 24 hours through 360 degrees,
Err... no.
Its more like 361 degrees in 24 hours.
The extra degree is needed to keep noon at zenith, otherwise the sun would
be overhead at midnight six months from now.

0
|



0 - Sun - 0
*



|
0

For example, if our year was zero days long, then Earth would need to rotate
90 degrees each quarter to keep the sun overhead. The moon does this as it
faces the Earth. If our year were 4 days long, then the Earth would need to
rotate 360+90 = 450 degrees each day. As it happens, our year is (roughly)
360 days long, so the Earth needs to rotate 361 degrees from noon to noon.
If the Earth spun in the opposite direction (sunrise in the West, sunset in
the East) a 359 degree rotation would be needed.
A siderial day (about 4 minutes less than a solar day) is 360 degrees. You
may have noticed that the constellation Orion is in our (Northern) Winter
sky, but is absent from our Summer nights. It is still there, of course, but
it is seen in our Summer days when you cannot see starlight too easily.
In the diagram above the star (*) on the right is "behind" the sun when the
Earth (0) is at the left of the diagram, and therefore in the sky at noon.
Six months later, the star is overhead at midnight, between the Sun and that
star. But don't take my word for it. Go outside each night and look. Now
and for the rest of your life. I do. You'll be amazed at what you'll find,
just by looking and wondering, discovering for yourself, instead of
listening to what others tell you.
Incidentally, the 360 degree division of the circle was chosen by the
ancient Babylonians because if this.

Androcles


Albert
violates this basic premise by determining stellar circumpolar motion
describes a circle in 24 hours (astronomical 24 hour day)

You never did explain how I can rotate 360 degrees, move
partway around an orbit, and still be facing the center.

Paint a circle on the ground. Stand on the circle,
facing the center. Rotate exactly 360 degrees.
You are again facing the center. Now, without
changing orientation, step one pace
to the right. Are you still facing the center?

- Randy

(Randy Poe) wrote in message . com...
(Oriel36) wrote in message . com...
The first principle of any investigation into any physical phenomena
is that the Earth rotates in 24 hours through 360 degrees,Albert
violates this basic premise by determining stellar circumpolar motion
describes a circle in 24 hours (astronomical 24 hour day)

You never did explain how I can rotate 360 degrees, move
partway around an orbit, and still be facing the center.

Paint a circle on the ground. Stand on the circle,
facing the center. Rotate exactly 360 degrees.
You are again facing the center. Now, without
changing orientation, step one pace
to the right. Are you still facing the center?

- Randy

You've just described (in part) how to construct a frame of reference
for a specific purpose. To complete your description you have to
describe how to mark off degrees on the circle and what precisely a
"pace" is.

Patrick

Dear greywolf42:

"greywolf42" wrote in message
...
greywolf42 wrote in message
...
Patrick Reany wrote in message
om...
Did SR invent the concept of 'frame of reference'?

First, what is a "frame of reference"? A "frame of reference" is an
aggregation of matter (usually nearly "rigid" in the Euclidean sense,
in which spacio-temporal measurements can be accurately made
according
to some operational procedure. The spacial, or distance, measurements
can be done by scratching equally spaced marks in the floor and walls
of the frame to aid in making measurements of visible things which
are
at certain points in the frame at certain times, according to a
conveniently place set of synchronized clocks.

So, did SR (or rather Einstein) invent the concept of "frame of
reference"? I say no.


{snip the rest of the irrelevant attempt at philosophy.}

That should be simple to decide. Simply find a reference where the
words
"frame of reference", or even "frame" are used prior to 1905. Your
own,
personal redefinitions and "imaginations" of historical documents are
irrelevant.

Well, that settles that. Patrick can't find a pre-Einstein reference to
a
'frame.' So, I guess it was Einstein (SR) that invented the concept of
'frame of reference.'

Does Galileo count, with his "ship's cabin" relativity?

David A. Smith