On 25 Feb, 12:04, wrote:
On 24 Feb, 11:58, Tom Roberts wrote:

wrote:
But i am still very confused about the actual concept, if distances
really is a velocity dependent artefact.

Distance is NOT "velocity dependent", it is PATH dependent. But for
observers in two different inertial frames, the natural way of measuring
the distance between two objects is along different paths through
spacetime, and thus they obtain different values.


Ooops sometimes i am just to fast...

Yes Tom distance is velocity dependent and even trajectory(vector?)
dependent in SR. The pulsefront is receeding with a velocity of 424
264 km/s from earth but only receeding with 300 000 km/s from
**********ship***********
although both ship and planet occupied origo at t0, if Randy Poe can
see this with a quick look so should you be able.


One can however argue the pulsfront actually did travel this
*distance* during a time spann of just 1/70.7 seconds in the inertial
frame of the ship *due to time dilation*(i hope you agree with me on
this).

Ok you want to call a distance a path that however does not change the
fact the paths/distances light traveled is unsymmetric thus light
travel variant through space.

NOTE: I do not claim light to be measured variant between different
frames.
I claim that different inertial frames have different lightpath
lengths but i would say distances.

So why would then different frames measure light velocity to be
invariant d/t. Well if you let a defined constant the meter be a
circular argument with a built in idea of light propagating invariant
in space , it is actually unavoidable due to definition.

If you can make a *spatial* vektor/lightpath of 300 000 km to only
have travelled 4243 km within the ships inertial frame during one
second (because that is the length the pule must travel during the
timespann of the inertial frame, or if you prefer the time it *MUST*
be measured to).

You are on the way to selfdelusion or to be a very slick conman. If
you then find out your mistake and try to cover it up by changing the
definition and make it cirular by *DEFINITION/STATEMENT* "A METER IS
THE DISTANCE THE LIGHT TRAVEL IN VACUUM IN 1/299,792,458 OF A SECOND"
i would personally call it fraud.

But more probably people at the SI was mislead by scientists to
beleive that light travels invariant through *SPACE*, which it
obviously do not.





For example, consider the distance between earth and polaris (considered
as fixed points in a single inertial frame). In their mutual rest frame,
they are a distance D apart, and this distance is naturally measured
along a path which is simultaneous in the earth+polaris frame (that's
what we mean by distance measured in a specific frame). An observer in a
spaceship moving at 0.866 c relative to the earth+polaris frame measures
0.5 D as the distance between them, and this distance is likewise
measured along a path that is simultaneous in the spaceship frame. These
two paths are DIFFERENT PATHS through spacetime, and that is why they
measure different values. For instance, these two paths have the same
objects as endpoints, but they end at them at different points in
spacetime (specifically different values of time, measured in either frame).

Distance is always path dependent, in any manifold. The distance from
Chicago to New York is different if one measures via New Orleans or
measures along a straight line. In this case the straight-line value is
clearly what we normally mean by "distance", as it is measured along a
spatial geodesic.

To try to hide an obvious flaw within a theory by redefinition, and
word games does not serve you well Tom i know you know better than
this.

v=d/t and once that definition did make sense it even make sense if
let time be variant due to timedilation. But it does not make sense
anymore once you give up the "d" as a constant. Because you get a
velocity that actually do not tell you how long you travel path / time
unit, the only thing it will measure is the *local* velocity AKA the
inertial velocity.

I know you are smart enough to see this. But there maybe to much time
invested in the subject to admit it. It is easier to try to tweak the
parameters of the flawed theory to make them look consistent.

But ultimately Tom any house build on a ground of pure mud will not
survive, you may try to tweak the structure to fit the ground but in
the end it is not good idea, find some better ground to build the new
house on.





But in the earth/polaris case above BOTH paths are spatial geodesics. In
spacetime, the distance between two objects is analogous to the distance
between two parallel lines in Euclidean geometry:

| |
|* |
| * |
| * |
| * |
| * |
| *|
| |
|------|
| |

Clearly the "distance between the parallel lines" is different for the -
path and the * path, but both paths are spatial geodesics. In spacetime
the parallel lines are the objects' worldlines (extending along the time
axis of their mutual rest frame); due to the hyperbolic structure of
spacetime the - path (i.e. the distance in the earth-polaris frame) is
larger than the * path (in the spaceship frame).

Would that really imply that each velocity vector(inertial frame) has
it's own universe.

No. For the same reason the two different Chicago-New York distances do
not imply the two measurements have their own USA. And for the same
reason the different distance for the * and - paths do not imply they
have their own planes.

You know i did not mean it litteraly i meant that each inertial frame
would raise the question about remap the universe, i do not think it
is a good idea. Let the distance be a spatial constant that is not
vector and velocity dependent AKA frame dependent.Would be a much
better idea Tom.

If time in the end turn out to be variant and velocity dependent. We
will see further along the road, but to let the Lorentz transformation
reduce the validity of measure tools of length (meter/distance) is
just absurd.

If you want to claim realworld contraction in an inertial frame (i do
you not, but some relativists do), then only use it for objects along
that worldline (inertial frame) do not claim that the actual distance
change.
Because if you do we have to find another word for length, and we end
up in absurdum resonemang about proper meter proper distance. There is
only one meter the actual contraction is *just a factor* not a new
meter. And the idea that *ACTUAL DISTANCES* not same between different
"vectors and velocities" aka inertial frames is just *SILLY*.

The only thing that matter for distance measurement is *LOCATION* in
space X,Y,Z and a unit *CONSTANT*. You people should not have ****ed
with that constant because now it become a vector and velocity
dependent *VARIABLE* and it just do not make sense.

And as everyone can see talking about velocities v=d/t with a meter
set that is framedependent just do not make sense.



[... nonsense based on the above misconception omitted]

Snip clip doesn't change fact you do not want people to know that
light travel variant in space but invariant between frames.

Best regards Jonas Thörnvall



Tom Roberts- Dölj citerad text -

- Visa citerad text -- Dölj citerad text -

- Visa citerad text -- Dölj citerad text -

- Visa citerad text -

wrote:
On 24 Feb, 11:58, Tom Roberts wrote:
Distance is NOT "velocity dependent", it is PATH dependent. But for
observers in two different inertial frames, the natural way of measuring
the distance between two objects is along different paths through
spacetime, and thus they obtain different values.

Yes Tom distance is velocity dependent

Saying that is FAR too imprecise -- you MUST say what you mean by
"distance". For instance, "distance between objects at rest in this
inertial frame measured in this frame", is completely independent of the
motion of that frame. But as I showed before, the "distance between
these two objects at rest in inertial frame A measured in inertial frame
B" depends on the relative motion of A and B -- but this is MUCH better
understood as a path dependence rather than a "velocity dependence" (or
even a "relative velocity dependence").


The pulsefront is receeding with a velocity of 424
264 km/s from earth but only receeding with 300 000 km/s from earth

[TYPO? one of those "earth"s should be "ship"]

I was discussing only your statement about "distance as a
velocity-dependent artifact". But if this pulsefront is a light pulse
propagating in vacuum, your statement here is wrong.


Ok you want to call a distance a path

I do not do so -- "distance" and "path" are quite different concepts..
Distance is inherently measured ALONG a path. And between a given pair
of objects there can be many different paths between them, and many
different values of distance along those paths.

To qualify as "distance measured in inertial frame A", the path used
must be simultaneous in frame A.


I claim that different inertial frames have different lightpath
lengths but i would say distances.

Yes, differently-moving inertial frames will measure different distances
IN EACH FRAME for the path that a given light pulse travels. This is
so because the foliation of spacetime into space and time is different
for different frames, and the "distance along the light path measured in
this frame" is inherently measured in the spatial submanifold of that
frame. This is a different way of describing the path dependence I
described earlier, because "distance in this frame" is always measured
along a path that is simultaneous in that frame -- for a given light ray
the measurement of distance will be along different paths in different
frames.


So why would then different frames measure light velocity to be
invariant d/t. Well if you let a defined constant the meter be a
circular argument with a built in idea of light propagating invariant
in space , it is actually unavoidable due to definition.

So use a pre-1983 definition of the meter. Still the speed of light in
vacuum is invariant (had this not been solidly established before 1983,
the meter would never have been redefined). Yes, different frames
measure different "distance traveled by the light pulse measured in this
frame", but they also measure different flight time intervals for that
light pulse, and the ratio is independent of frame. The different frames
measure both "distance traveled by the light pulse" and "travel time of
the light pulse" along different paths, but the geometry of SR is such
that the ratio is independent of frame; the world we inhabit is observed
to be fully consistent with this (locally).


But more probably people at the SI was mislead by scientists to
beleive that light travels invariant through *SPACE*, which it
obviously do not.

You are confused, at least in part by your lack of precision. Different
inertial frames have a different view of what "space" means. And a
different view of what "time" means. This COMPLETELY resolves the issue.


Tom Roberts

On 24 Feb, 11:58, Tom Roberts wrote:
wrote:
But i am still very confused about the actual concept, if distances
really is a velocity dependent artefact.

Distance is NOT "velocity dependent", it is PATH dependent. But for
observers in two different inertial frames, the natural way of measuring
the distance between two objects is along different paths through
spacetime, and thus they obtain different values.

For example, consider the distance between earth and polaris (considered
as fixed points in a single inertial frame). In their mutual rest frame,
they are a distance D apart, and this distance is naturally measured
along a path which is simultaneous in the earth+polaris frame (that's
what we mean by distance measured in a specific frame). An observer in a
spaceship moving at 0.866 c relative to the earth+polaris frame measures
0.5 D as the distance between them, and this distance is likewise
measured along a path that is simultaneous in the spaceship frame. These
two paths are DIFFERENT PATHS through spacetime, and that is why they
measure different values. For instance, these two paths have the same
objects as endpoints, but they end at them at different points in
spacetime (specifically different values of time, measured in either frame).

Distance is always path dependent, in any manifold. The distance from
Chicago to New York is different if one measures via New Orleans or
measures along a straight line. In this case the straight-line value is
clearly what we normally mean by "distance", as it is measured along a
spatial geodesic.

But in the earth/polaris case above BOTH paths are spatial geodesics. In
spacetime, the distance between two objects is analogous to the distance
between two parallel lines in Euclidean geometry:

| |
|* |
| * |
| * |
| * |
| * |
| *|
| |
|------|
| |

Clearly the "distance between the parallel lines" is different for the -
path and the * path, but both paths are spatial geodesics. In spacetime
the parallel lines are the objects' worldlines (extending along the time
axis of their mutual rest frame); due to the hyperbolic structure of
spacetime the - path (i.e. the distance in the earth-polaris frame) is
larger than the * path (in the spaceship frame).

Would that really imply that each velocity vector(inertial frame) has
it's own universe.

No. For the same reason the two different Chicago-New York distances do
not imply the two measurements have their own USA. And for the same
reason the different distance for the * and - paths do not imply they
have their own planes.

[... nonsense based on the above misconception omitted]

Tom Roberts

If any of you SR promotors really think that light actually travels
invariant through space.

Tell me.

Ship travel 0.9999 pass planet origo along x-axis lightpulse sent
straight along y-axis. At t0 passing origo.
t0=0
t1=1 sek

1. Distance between ship and pulsefront t1 (origo planet frame)?
2. Distance between planet and pulsefront t1 (origo planet frame)?

To have light invariant the above would have to be the same you can
not chase light, you know that as well as i am.

3. At t1 the time passed in frame origo is one second.
How far have the light travelled from planet origo.

4. At t1 the time passed in frame ship only 0.01414 sec
So tell me how far have light travelled from within the ship frame at
moment t1.

You know as well as i you can not answer these question because the
answers would make SR an invalid theory, so you all will duck the
questions.

But i just felt i had to notice those who still beleived SR to be a
working theory.

Best regards Jonas Thörnvall

wrote in message ups.com...

[snip]

If any of you SR promotors really think that light actually travels
invariant through space.

We know that every human who ever tried to measure the
speed of light, found the same value, no matter where it
came from. We have learned to live with that.

Tell me.

Ship travel 0.9999 pass planet origo along x-axis lightpulse sent
straight along y-axis. At t0 passing origo.
t0=0
t1=1 sek

1. Distance between ship and pulsefront t1 (origo planet frame)?
2. Distance between planet and pulsefront t1 (origo planet frame)?

In the ship's frame the pulse has trajectory
x' = 0
y' = c t'
so in the planet's frame it has trajectory
g ( x - v t ) = 0
y = c g ( t - v/c^2 x )
giving pulse trajectory:
x = v t
y = sqrt(c^2-v^2) t


The ship has trajectory
x = v t
y = 0

So, according to the planet, the distance between ship and
pulse at time t is
d = sqrt(c^2-v^2) t
and the distance between ship and the planet at time t is
d = v t

Note that, according to the ship, the pulse between itself
and the pulse at time t' is
d' = c t'


To have light invariant the above would have to be the same

To have light invariant, everyone measures the speed of the
pulse with respect to himself to have the value c. That is
by *definition* what is meant by what you call "invariant light".

you can
not chase light, you know that as well as i am.

3. At t1 the time passed in frame origo is one second.
How far have the light travelled from planet origo.

Use the trajectory of the pulse in the planet's frame:
x = v t
y = sqrt(c^2-v^2) t
giving distance
d = sqrt( x^2 + y^2 ) = ... = c t


4. At t1 the time passed in frame ship only 0.01414 sec
So tell me how far have light travelled from within the ship frame at
moment t1.

Explain what you mean exactly with the phrase "At t1 the time
passed in frame ship". Keep in mind that you are talking about
two clocks he (1) the clock on the planet showing t1,
and (2) a clock on the ship.
Moment t1 is an event on the planet. Not on the ship.

Use variables in stead of numeric values.

Dirk Vdm



You know as well as i you can not answer these question because the
answers would make SR an invalid theory, so you all will duck the
questions.

But i just felt i had to notice those who still beleived SR to be a
working theory.

Best regards Jonas Thörnvall

On 25 Feb, 14:53, Tom Roberts wrote:
wrote:
On 24 Feb, 11:58, Tom Roberts wrote:
Distance is NOT "velocity dependent", it is PATH dependent. But for
observers in two different inertial frames, the natural way of measuring
the distance between two objects is along different paths through
spacetime, and thus they obtain different values.

Yes Tom distance is velocity dependent

Saying that is FAR too imprecise -- you MUST say what you mean by
"distance". For instance, "distance between objects at rest in this
inertial frame measured in this frame", is completely independent of the
motion of that frame. But as I showed before, the "distance between
these two objects at rest in inertial frame A measured in inertial frame
B" depends on the relative motion of A and B -- but this is MUCH better
understood as a path dependence rather than a "velocity dependence" (or
even a "relative velocity dependence").

The pulsefront is receeding with a velocity of 424
264 km/s from earth but only receeding with 300 000 km/s from earth

[TYPO? one of those "earth"s should be "ship"]

I was discussing only your statement about "distance as a
velocity-dependent artifact". But if this pulsefront is a light pulse
propagating in vacuum, your statement here is wrong.

Ok you want to call a distance a path

I do not do so -- "distance" and "path" are quite different concepts..
Distance is inherently measured ALONG a path. And between a given pair
of objects there can be many different paths between them, and many
different values of distance along those paths.

Yes i know and when i refer to path i mean a straight line between two
objects, also known as flight path/distance, i do not mean a wrinkled
paper, sometimes refered to as spacetime no vacuum do not budge.

Contrary to *POPULAR BELEIF* a object travel at velocities close to c
can not distort the cordinate system the planets it travel by stars
will not budge to the object, and the spacetime will not be wrinkled
like a sheet.

Because spacetime do not exist outside the concept of SR and Miskowsky
spacetime, so no distances do not get shorter with higher velocities.
That someone pulled of to make people think so is actually a major
psycologial achievment.

However it is possible that *TIME* distorts and i have not trouble
with that, i even can buy deformation of the travelling object itself.
However the space itself will not budge for the object it will be
there going on in it's own paste.

Tom that you beleive that there are more then one straight line in
space between two points in space, does not necessarily mean i have to
share that beleif.

Actually you beleive there are as many such lines of different lengths
A to B distances in space, that there are paths in spacetime.

*I* do not share that beleif. I beleive all the ships travel in the
same cordinate system and that system will not budge nor deformate
whatsoever just because of the velocity of the ship. It is the other
way around you see, maybe and just maybe the local time is affected i
highly doubt the contraction of object but it may be there or may just
be a mat


Ooops in hurry later
To qualify as "distance measured in inertial frame A", the path used
must be simultaneous in frame A.

I claim that different inertial frames have different lightpath
lengths but i would say distances.

Yes, differently-moving inertial frames will measure different distances
IN EACH FRAME for the path that a given light pulse travels. This is
so because the foliation of spacetime into space and time is different
for different frames, and the "distance along the light path measured in
this frame" is inherently measured in the spatial submanifold of that
frame. This is a different way of describing the path dependence I
described earlier, because "distance in this frame" is always measured
along a path that is simultaneous in that frame -- for a given light ray
the measurement of distance will be along different paths in different
frames.

So why would then different frames measure light velocity to be
invariant d/t. Well if you let a defined constant the meter be a
circular argument with a built in idea of light propagating invariant
in space , it is actually unavoidable due to definition.

So use a pre-1983 definition of the meter. Still the speed of light in
vacuum is invariant (had this not been solidly established before 1983,
the meter would never have been redefined). Yes, different frames
measure different "distance traveled by the light pulse measured in this
frame", but they also measure different flight time intervals for that
light pulse, and the ratio is independent of frame. The different frames
measure both "distance traveled by the light pulse" and "travel time of
the light pulse" along different paths, but the geometry of SR is such
that the ratio is independent of frame; the world we inhabit is observed
to be fully consistent with this (locally).

But more probably people at the SI was mislead by scientists to
beleive that light travels invariant through *SPACE*, which it
obviously do not.

You are confused, at least in part by your lack of precision. Different
inertial frames have a different view of what "space" means. And a
different view of what "time" means. This COMPLETELY resolves the issue.

Tom Roberts

On Feb 25, 9:02 am, wrote:



But i just felt i had to notice those who still
beleived SR to be a working theory.

a) You can minimise the effect of a moving skunk
by moving wrt the skunk spatially or temporally or both.

b) a^2 + b^2 = c^2

Do you agree ?
Because that is about all SR says:


"The [ ] Incompatibility of the Law of Propagation of
Light with the Principle of Relativity [is only] Apparent"
http://www.bartleby.com/173/7.html

Time-independent Maxwell equations
Time-dependent Maxwell's equations
Relativity and electromagnetism
http://farside.ph.utexas.edu/teachin.../lectures.html

Maxwell's equations in classic electrodynamics
(classic field theory)_
a) Maxwell equations (no movement),
b) Maxwell equations (with moved bodies)
http://www.wolfram-stanek.de/maxwell...assic_extended

As for Tom's gyrations about inertial frames:

A Lorentz transformation or any other coordinate
transformation will convert electric or magnetic
fields into mixtures of electric and magnetic fields,
but no transformation mixes them with the
gravitational field.
http://www.aip.org/pt/vol-58/iss-11/p31.html

Sue...






Best regards Jonas Thörnvall-

wrote:
On 25 Feb, 14:53, Tom Roberts wrote:
wrote:
On 24 Feb, 11:58, Tom Roberts wrote:
Distance is NOT "velocity dependent", it is PATH dependent. But for
observers in two different inertial frames, the natural way of measuring
the distance between two objects is along different paths through
spacetime, and thus they obtain different values.
Distance is inherently measured ALONG a path. And between a given pair
of objects there can be many different paths between them, and many
different values of distance along those paths.

Yes i know and when i refer to path i mean a straight line between two
objects, also known as flight path/distance, i do not mean a wrinkled
paper, sometimes refered to as spacetime no vacuum do not budge.

Refer to the diagram I showed earlier. I am discussing two different
straight line paths between the two objects in question. There is no
"wrinkled paper" in my discussion at all, and I have no idea where you
got that from.


Contrary to *POPULAR BELEIF* a object travel at velocities close to c
can not distort the cordinate system the planets it travel by stars
will not budge to the object, and the spacetime will not be wrinkled
like a sheet.

I know of no such "popular belief" -- this seems to be purely a figment
of your personal imagination.

Yes, differently moving observers separate spacetime into space and time
in a different manner (and thus measure different distances between a
given pair of objects). But there is no "wrinkling" at all.


Because spacetime do not exist outside the concept of SR and Miskowsky
spacetime, so no distances do not get shorter with higher velocities.

I repeat: you MUST be more precise, and state specifically what you men
by "distance" (i.e. how is it measured, and by whom).


Tom that you beleive that there are more then one straight line in
space between two points in space,

I never claimed that. Read what I wrote more carefully. I point out that
in SR there are different straight lines in space between two OBJECTS,
and that these different spatial straight lines intersect the objects'
worldlines at different points.


Tom Roberts

On 22 Feb, 12:33, wrote:
Given a X,Y,Z cordinate system with "earth in origo" a spaceship "A"
travels along X axis in a
velocity close to c.
Assuming the side of spaceship is along the Y
axis and a pulsecanon is aligned along Y(side of ship) it fire a
pulse
of one Plank length in a straight line along Y.

1. What will the actual trajectory of the pulse be?
(will it not at all be affected by the ships trajectory and travel in
a straight line along Y, i have a hard time to imagine it travelling
in a straight line parallell with ship c along the X axis but maybe
it
will?) or maybe it will take have a trajectory like a ball thrown
from
a car left side but that would be a velocity dependent trajectory
dependent on ~c and c?

2. Maybe a very stupid question, is it possible for the pulse(given a
light pulse) to expand not only in a positive direction from the
pulse
canon?
Maybe it is not quite clear what i mean, must the pulse always travel
positive from the emitter given a light or radio pulse, even if the
emitter is an object moving at ~c.

Could anyone be so kind make plot the trajectorie for me assuming
planet earth at rest in origo and ship travel positive along x-axis.
The ship passing origo "earth frame t0 sec" firing pulse postive in y-
axis
could anyone plot out for me "ship" and "pulse front" respective
origo
"earth frame t1 sec".

Where is lightpulse with respect to origo "earth" anyone?
The ship travels very close to ~c let us say indistinguasable.

I would also like to know how the trajectory would look in 0.9 0.8
0.7
0.6 c ...... and so on if someone got the time.

Best regards JT

So.... when?

On 22 Feb, 14:56, wrote:
On 22 Feb, 14:25, "Dirk Van de moortel" dirkvandemoor...@ThankS-NO-

SperM.hotmail.com wrote:
wrote in ooglegroups.com...

[snip]

Ok i am lazy is there a simple freeware graph program someware.

Su
http://www.google.com/search?q=free+...tware+download

Dirk Vdm

Hello Dirk if i understand correct (plotted correct) the ligh pulse
will travel straight along the y-axis without deformation, regardless
of speed.

That makes me wonder a little, because after t1(earth/planet time 1
sec) the light beam have travelled 300 000 km relative earth.

But for the ship *distance* to pulsefront we would have to use
pythagoras theorem correct?

424 264 km

That would be the distance as measured from earth frame between ship
and pulsefront correct?

Assume velocity ship 0.9999 c we have a dilation factor of 1/70.7 sec
for inertial frame A ship.

1 sec earth frame =0.014144 ship frame

Should i conclude that the distance to pulsefront from within the
shipframe is 0.01414*424 264 ?

And that the distance to earth is 0,01414*300 000?

Is there other distances from within the ship frame to the pulsefront
and planet? "At moment t1"=clock 1 sec passed earth frame.

I know that length contraction occur in the ship frame does this apply
for space and things outside the ship?

Is there such a thing as distance contraction in SR or does it only
refer to the actual things belonging to the moving frame?

In my mind it would be natural to have the distance as a constant
between the frames 300 000/0,01414 and 424 264/0,01414 but that is of
course wrong according to SR.

Is distance really variant between frames in SR?
And what about the hypotenusa argument is that really invoked in SR?

Best regards Jonas Thörnvall

Yes it certainly has.......................