- This refers to a post I made last week, but which thread I can't access in
my Newsgroup reader!

another difference between LET and SRT?


| Von:Bruce Seiler )
|
| Harry wrote:
|
| Perhaps (that's why I ask!) there is another difference between LET and
| SRT.
|
| LET accepts the existence of an observer-independent and reference-frame
| independent reality.
| - It seems to me that the current interpretation of SRT does not agree,
| and
| is more like the film "Matrix".
|
| This is related to my statement in an earlier posting that perhaps went
| unnoticed, and that I like to refine he
| "Measurement instruments are, according to SRT, unaffected by velocity."
|
| Should I add: "in one's own frame of reference"?
| Or is it so that any affection by velocity of measurement instruments in
| movement relative to us is claimed to be only apparent and not real?
|
| What is the official interpretation?!
|
| Harald
|
| I'm not official, but I'll reply anyway.
|
| I think you have it backwards. SR asserts an observer-independent and
| reference-frame independent reality even more than LET. In SR, events
exist
| quite independent of any reference frame.

SNIP

| LET fudges a bit. There is a one, true reference frame where Maxwell's
| equations
| are literally true and other frames where they only appears to be true.
So
| LET requires a reality which is true but forever hidden.

| SR does have the distance and the time between two events vary with
| different
| frames. So what is the "true" time and space separations of the above
| event?
| That is like asking if a 2 by 4 board is really 2" wide by 4" deep or is
4"
| wide
| by 2" deep. Rotating the board didn't physically change it at all. And
in
| SR,
| changing to a different reference system doesn't change reality at all
even
| if it does change the coordinate values.
|
| In the end, the conflict isn't between SR and observer-independent reality
| but between SR and what you think should be observer independent.
|
| Bruce Seiler

I agree with that last remark.

My question is not what events SRT predicts, but what other claims about
reality it makes, explicitly *or implicitly*.
I doubt that according to most of you, SRT agrees with the consequence of
the above reasoning that a cube is both a cube and a non-cubic box,
depending on the reference frame.
In other words, according to SRT, does a cube have a reference-frame
independent physical reality or not?
My guess is that it has.
That's why I proposed to state that objects are claimed to be unaffected by
velocity (to ghytrfvbnmju7654 : relative velocity of course!) in the frame
in which they are in rest.
Or, alternatively, that only the shape in their rest frame is "real", and
that their shape in other frames is "apparent" (but what is meant with
that?! The basic hypothesis of SRT was that what one measures corresponds to
reality!...)

To elaborate on the "fudging" of LET: Does SRT require all reference frames
to be "true"?
But then the effects can not be "apparent", but must be true, right?

Harald

"Harry" wrote in message ...
- This refers to a post I made last week, but which thread I can't access in
my Newsgroup reader!

[snipped - if you don't mind]

|
| In the end, the conflict isn't between SR and observer-independent reality
| but between SR and what you think should be observer independent.
|
| Bruce Seiler

I agree with that last remark.

My question is not what events SRT predicts, but what other claims about
reality it makes, explicitly *or implicitly*.

Maybe SRT (and not only SRT) merely makes claims
about what can be measured. Maybe it doesn't even
talk about "reality".

I doubt that according to most of you, SRT agrees with the consequence of
the above reasoning that a cube is both a cube and a non-cubic box,
depending on the reference frame.
In other words, according to SRT, does a cube have a reference-frame
independent physical reality or not?
My guess is that it has.
That's why I proposed to state that objects are claimed to be unaffected by
velocity (to ghytrfvbnmju7654 : relative velocity of course!) in the frame
in which they are in rest.

That's a heavy construction:
You propose to
state that
objects are claimed to
be unaffected...
Of course you can state this, but it seems rather trivial,
since there *is* no (relative) velocity in the frame in which
they are at rest, so how could they possibly be affected by
it?

Or, alternatively, that only the shape in their rest frame is "real", and
that their shape in other frames is "apparent" (but what is meant with
that?! The basic hypothesis of SRT was that what one measures corresponds to
reality!...)

Don't you think that this is exactly how -de facto-
you *define* the concepts "real" and "apparent"
in the first place?
I.o.w. you could first define
"apparent" as "how it is measured"
and then
"real" as "apparent as seen in its restframe"
Do you have a good alternative?


To elaborate on the "fudging" of LET: Does SRT require all reference frames
to be "true"?
But then the effects can not be "apparent", but must be true, right?

Harald

Cheers,
Dirk Vdm

In article ,
Dirk Van de moortel wrote:

"Harry" wrote in message
...

My question is not what events SRT predicts, but what other claims about
reality it makes, explicitly *or implicitly*.

Maybe SRT (and not only SRT) merely makes claims
about what can be measured. Maybe it doesn't even
talk about "reality".

In fact, you can make that "physics in general", not "SRT". Talking about
any "reality" beyond what we observe and measure, falls into the realms of
metaphysics and philosophy, not physics.

--
Jon Bell Presbyterian College
Dept. of Physics and Computer Science Clinton, South Carolina USA

"Jon Bell" wrote in message ...
In article ,
Dirk Van de moortel wrote:

"Harry" wrote in message
...

My question is not what events SRT predicts, but what other claims about
reality it makes, explicitly *or implicitly*.

Maybe SRT (and not only SRT) merely makes claims
about what can be measured. Maybe it doesn't even
talk about "reality".

In fact, you can make that "physics in general", not "SRT".

that's why I added the parentheses...

Talking about
any "reality" beyond what we observe and measure, falls into the realms of
metaphysics and philosophy, not physics.

My point entirely, but I wanted to make it gently :-)

Dirk Vdm

Jon Bell wrote:

In fact, you can make that "physics in general", not "SRT". Talking about
any "reality" beyond what we observe and measure, falls into the realms of
metaphysics and philosophy, not physics.

Hypotheticals about unobserved things which lead to testable and correct
conclusions are kosher and necessary. A science built only on
observables with no ideal elements would be correct but extremely
incomplete and unproductive.

We allow mystery elements into science as postulates provided they are
coherent and they produce correct predictions. For example, Newton
modeled gravity as a force to account for the effects that masses have
on each other.

Bob Kolker

SNIP

Talking about
any "reality" beyond what we observe and measure, falls into the realms
of
metaphysics and philosophy, not physics.

My point entirely, but I wanted to make it gently :-)

Then we are back to (for physics) SRT=LET...

But in my opinion, such may be true for engineering, not for physics!

Harald

"Dirk Van de moortel" wrote
in message ...

"Harry" wrote in message
...
- This refers to a post I made last week, but which thread I can't
access in
my Newsgroup reader!

[snipped - if you don't mind]

You're welcome, it was just to make the connection!

| In the end, the conflict isn't between SR and observer-independent
reality
| but between SR and what you think should be observer independent.
|
| Bruce Seiler

I agree with that last remark.

My question is not what events SRT predicts, but what other claims about
reality it makes, explicitly *or implicitly*.

Maybe SRT (and not only SRT) merely makes claims
about what can be measured. Maybe it doesn't even
talk about "reality".

Well, a number of people shares your opinion. The funny thing is that little
word "maybe".

I doubt that according to most of you, SRT agrees with the consequence
of
the above reasoning that a cube is both a cube and a non-cubic box,
depending on the reference frame.
In other words, according to SRT, does a cube have a reference-frame
independent physical reality or not?
My guess is that it has.
That's why I proposed to state that objects are claimed to be unaffected
by
velocity (to ghytrfvbnmju7654 : relative velocity of course!) in the
frame
in which they are in rest.

That's a heavy construction:
You propose to
state that
objects are claimed to
be unaffected...
Of course you can state this, but it seems rather trivial,
since there *is* no (relative) velocity in the frame in which
they are at rest, so how could they possibly be affected by
it?

You seem to assume that the frame in which they are in rest is a preferred
frame, or the only option. Thus your reply seems to be an affirmation.
For example, a GPS satellite that refers to the ECI frame is claimed by SRT
to be affected, even from the viewpoint of a guest who is at rest inside
that satellite (OK, he will not last long, but that's not the point!).

Or, alternatively, that only the shape in their rest frame is "real",
and
that their shape in other frames is "apparent" (but what is meant with
that?! The basic hypothesis of SRT was that what one measures
corresponds to
reality!...)

Don't you think that this is exactly how -de facto-
you *define* the concepts "real" and "apparent"
in the first place?
I.o.w. you could first define
"apparent" as "how it is measured"
and then
"real" as "apparent as seen in its restframe"
Do you have a good alternative?

Normally a theory makes a claim about what is supposed to be unobserved
reality, and then constructs the observed reality from a hypothesis about
the way that this reality is measured.
*Then* if the measurements are conform, this supports the theory about
reality.
SRT seems to deviate from this rule, and I wonder if it is in fact unruly!

Cheers,
Harald

"Harry" wrote in message ...

"Dirk Van de moortel" wrote
in message ...

"Harry" wrote in message
...
- This refers to a post I made last week, but which thread I can't
access in
my Newsgroup reader!

[snipped - if you don't mind]

You're welcome, it was just to make the connection!

| In the end, the conflict isn't between SR and observer-independent
reality
| but between SR and what you think should be observer independent.
|
| Bruce Seiler

I agree with that last remark.

My question is not what events SRT predicts, but what other claims about
reality it makes, explicitly *or implicitly*.

Maybe SRT (and not only SRT) merely makes claims
about what can be measured. Maybe it doesn't even
talk about "reality".

Well, a number of people shares your opinion. The funny thing is that little
word "maybe".

like I said to John... I wanted to make the point gently.
Maybe I was a bit too gentle ;-)


I doubt that according to most of you, SRT agrees with the consequence
of
the above reasoning that a cube is both a cube and a non-cubic box,
depending on the reference frame.
In other words, according to SRT, does a cube have a reference-frame
independent physical reality or not?
My guess is that it has.
That's why I proposed to state that objects are claimed to be unaffected
by
velocity (to ghytrfvbnmju7654 : relative velocity of course!) in the
frame
in which they are in rest.

That's a heavy construction:
You propose to
state that
objects are claimed to
be unaffected...
Of course you can state this, but it seems rather trivial,
since there *is* no (relative) velocity in the frame in which
they are at rest, so how could they possibly be affected by
it?

You seem to assume that the frame in which they are in rest is a preferred
frame, or the only option. Thus your reply seems to be an affirmation.
For example, a GPS satellite that refers to the ECI frame is claimed by SRT
to be affected, even from the viewpoint of a guest who is at rest inside
that satellite (OK, he will not last long, but that's not the point!).

What you choose to call "preferred frame" is usually called
"restframe of an object". Every free falling object has its
own restframe. What is usually called a "preferred frame",
is some kind of hypothetical frame, that would play a special
role in the whole of physics.
So the concept of "preferred frame" was already reserved
for something else. This way I think my reply can't really be
an affirmation of what you had in mind.


Or, alternatively, that only the shape in their rest frame is "real",
and
that their shape in other frames is "apparent" (but what is meant with
that?! The basic hypothesis of SRT was that what one measures
corresponds to
reality!...)

Don't you think that this is exactly how -de facto-
you *define* the concepts "real" and "apparent"
in the first place?
I.o.w. you could first define
"apparent" as "how it is measured"
and then
"real" as "apparent as seen in its restframe"
Do you have a good alternative?

Normally a theory makes a claim about what is supposed to be unobserved
reality, and then constructs the observed reality from a hypothesis about
the way that this reality is measured.
*Then* if the measurements are conform, this supports the theory about
reality.
SRT seems to deviate from this rule, and I wonder if it is in fact unruly!

You say that this is what a theory normally does but I
think the problem is that we have no meaningful and/or
practical way to operationally define "reality", other of
course than the trivial (and rather useless) way that I
suggested previously.
That is the problem with metaphysical and philosophical
treatments of questions: it's so bloody hard to fix and use
workable definitions :-)
To me SRT (and not only SRT ;-) ) is just a set of
elegant postulates, translated into mathematical statements,
producing a geometrical system that seems to be doing a
good job predicting outcomes of interesting experiments.

Gezondheid,
Dirk Vdm

"Dirk Van de moortel" wrote
in message ...

SNIP

That's why I proposed to state that objects are claimed to be
unaffected
by
velocity (to ghytrfvbnmju7654 : relative velocity of course!) in the
frame
in which they are in rest.

That's a heavy construction:
You propose to
state that
objects are claimed to
be unaffected...
Of course you can state this, but it seems rather trivial,
since there *is* no (relative) velocity in the frame in which
they are at rest, so how could they possibly be affected by
it?

You seem to assume that the frame in which they are in rest is a
preferred
frame, or the only option. Thus your reply seems to be an affirmation.
For example, a GPS satellite that refers to the ECI frame is claimed by
SRT
to be affected, even from the viewpoint of a guest who is at rest inside
that satellite (OK, he will not last long, but that's not the point!).

What you choose to call "preferred frame" is usually called
"restframe of an object". Every free falling object has its
own restframe. What is usually called a "preferred frame",
is some kind of hypothetical frame, that would play a special
role in the whole of physics.
So the concept of "preferred frame" was already reserved
for something else. This way I think my reply can't really be
an affirmation of what you had in mind.

I think you do agree with yourself (smile):
You agree with the proposed phrase, but you think that it is trivial.

I failed to point out that it's not trivial, and that the rest frame is not
always one's reference frame.
The confusion between reference frame and rest frame is often made in
discussions, because it usually is the same.
I will try better after I come back from vacation.

Or, alternatively, that only the shape in their rest frame is
"real",
and
that their shape in other frames is "apparent" (but what is meant
with
that?! The basic hypothesis of SRT was that what one measures
corresponds to
reality!...)

Don't you think that this is exactly how -de facto-
you *define* the concepts "real" and "apparent"
in the first place?
I.o.w. you could first define
"apparent" as "how it is measured"
and then
"real" as "apparent as seen in its restframe"
Do you have a good alternative?

Normally a theory makes a claim about what is supposed to be unobserved
reality, and then constructs the observed reality from a hypothesis
about
the way that this reality is measured.
*Then* if the measurements are conform, this supports the theory about
reality.
SRT seems to deviate from this rule, and I wonder if it is in fact
unruly!

You say that this is what a theory normally does but I
think the problem is that we have no meaningful and/or
practical way to operationally define "reality", other of
course than the trivial (and rather useless) way that I
suggested previously.
That is the problem with metaphysical and philosophical
treatments of questions: it's so bloody hard to fix and use
workable definitions :-)

True!

To me SRT (and not only SRT ;-) ) is just a set of
elegant postulates, translated into mathematical statements,
producing a geometrical system that seems to be doing a
good job predicting outcomes of interesting experiments.

Gezondheid,

Jij ook!

Harald

Harry wrote:

| Von:Bruce Seiler )
| ...
| In the end, the conflict isn't between SR and observer-independent reality
| but between SR and what you think should be observer independent.
|
| Bruce Seiler

I agree with that last remark.

My question is not what events SRT predicts, but what other claims about
reality it makes, explicitly *or implicitly*.
I doubt that according to most of you, SRT agrees with the consequence of
the above reasoning that a cube is both a cube and a non-cubic box,
depending on the reference frame.
In other words, according to SRT, does a cube have a reference-frame
independent physical reality or not?
My guess is that it has.
That's why I proposed to state that objects are claimed to be unaffected by
velocity (to ghytrfvbnmju7654 : relative velocity of course!) in the frame
in which they are in rest.
Or, alternatively, that only the shape in their rest frame is "real", and
that their shape in other frames is "apparent" (but what is meant with
that?! The basic hypothesis of SRT was that what one measures corresponds to
reality!...)

To elaborate on the "fudging" of LET: Does SRT require all reference frames
to be "true"?
But then the effects can not be "apparent", but must be true, right?

Harald

I still don't see any deep difference between claims about reality between
SR and NM. In both NM and SR, some of an objects properties are
frame-independent and some are not. Both would say an object kinetic energy
is frame dependent. Both say an object's mass is frame-indepedent (using the
invariant mass for an object's mass in SR). On the other hand, NM says all
speeds are frame depenent while SR says the speed of c is frame independent.
All in all, SR and NM are much more similar than NM was to Aristotle.

SR doesn't say a cube is a cube in some frames and a non-cube in others. It
says an object can be a cube in some frames and a non-cube in others. You
are assuming an object that is a cube in some frames ought to be a cube in
all frames. However that is just an assumption on your part. It's a natural
assumption for Newton to make because he had no evidence to the contrary.
We do.

You are deeply concerned with what properties are true and what are apparent.
What do you mean by that? It sounds like you mean "true" properties are frame-
independent and "apparent" are frame-dependent. It troubles you that an
object's
length changes if the velocity changes. Well, it also changes if I rotate the
object. You may say that isn't a "true" change because the object didn't
"really" change. Well, in SR, a velocity change is a type of rotation. And
rotations change measured quantities without physically changing the object.

By the way, yes: SR does require all inertial reference frames to be equally
valid.
Wayne Throop used to point out that rotations can have a real affect even if
they didn't physically change the rotated object using the example of skis that
fit into a car only if placed diagonally .

Finally, if you are worried about what modern physics has to say about the
nature
of reality, why not worry about QM instead of SR? QM is much more odd.

Bruce Seiler