On Feb 22, 8:56 am, wrote:
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?

Yes. Look up "stellar aberration", where the position of stars
in the sky changes depending on earth's movement relative to the
star. The Lorentz contraction was proposed by Lorentz to
explain this effect in terms of contraction of stellar
distances.

Einstein's contribution was to show how the Lorentz
contraction is a consequence of deeper principles.


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?

Apparently.

And what about the hypotenusa argument is that really invoked in SR?

I believe that's the essence of the Lorentz theory of stellar
aberration.

- Randy

On 22 Feb, 15:23, "Randy Poe" wrote:
On Feb 22, 8:56 am, wrote:

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?

Yes. Look up "stellar aberration", where the position of stars
in the sky changes depending on earth's movement relative to the
star. The Lorentz contraction was proposed by Lorentz to
explain this effect in terms of contraction of stellar
distances.

Einstein's contribution was to show how the Lorentz
contraction is a consequence of deeper principles.



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?

Apparently.

I now have to ask you if it also is vector dependent, is there
different distances if travel towards or away from object.


Suppose the ship was travelling towards the planet instead and at same
place at moment t1 would the distance be different in SR?

Is it vector dependent to?


And what about the hypotenusa argument is that really invoked in SR?

I believe that's the essence of the Lorentz theory of stellar
aberration.

To have the distant as a variant make me abit confused about the
arguments in SR. For me it seem impossible for ships travelling
different vectors to have different distances to planet X when passing
a cordinate in space and same for velocities.

I understand that the argument is rather mathematical built on
definitions but invariant distances seem very foreign for me because
it is very hard for me to use my logic exploring the arguments of SR.

I know little/nothing about mathematics but if distances is variant
does it make sense to talk about invariant light paths betwenn frames.

I know you think i am in deep water now, but some features of SR i
have a hard time to analyse by pure logic.

Best regards Jonas Thörnvall

- Randy

wrote in message ups.com...
On 22 Feb, 14:25, "Dirk Van de moortel"
wrote:
wrote in message
oups.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.

No, in the setup you sketched, it will travel straight along the
ship's y'-axis, regardless of speed.
It will not travel straight along the Earth's y-axis, but along a
straight line with equation
y = sqrt( c^2/v^2 - 1 ) x
the slope of which depends on the speed v.

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

Yes.
If you take the equations
x = v t
y = sqrt(c^2-v^2) t
you see that the velocity components in the x-direction and in the
y-direction are given by
x/t = v
y/t = sqrt(c^2-v^2) ,
so the composed velocity in the light signal's direction is then
sqrt( (x/t)^2 + (y/t)^2 ) = c
as expected.

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?

If you make your drawing, you will see that after an Earth-time t the
ship is at point
(x,y) = ( v t , 0 )
and the pulse front is at point
(x,y) = ( v t , sqrt(c^2-v^2) t )
the distance between which is
sqrt(c^2-v^2) t .

On the other hand, going to the frame of the ship again, the
signal's equations are
x' = 0
y' = c t'
and the Earth obeyes the equations
x' = - v t'
y' = 0 .

So you see that after a ship-time t', the signal is at point
(x',y') = ( 0 , c t' )
and the Earth is at point
(x',y') = ( -v t' , 0 )
the distance between which, as you can verify, is
sqrt(c^2+v^2) t'

Does this help?
In the remainder you used numeric values which destroy all
interesting bits about this, so I skipped it.

Dirk Vdm

On 22 Feb, 16:03, wrote:
On 22 Feb, 15:23, "Randy Poe" wrote:





On Feb 22, 8:56 am, wrote:

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?

Yes. Look up "stellar aberration", where the position of stars
in the sky changes depending on earth's movement relative to the
star. The Lorentz contraction was proposed by Lorentz to
explain this effect in terms of contraction of stellar
distances.

Einstein's contribution was to show how the Lorentz
contraction is a consequence of deeper principles.

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?

Apparently.

I now have to ask you if it also is vector dependent, is there
different distances if travel towards or away from object.

Suppose the ship was travelling towards the planet instead and at same
place at moment t1 would the distance be different in SR?

Is it vector dependent to?

And what about the hypotenusa argument is that really invoked in SR?

I believe that's the essence of the Lorentz theory of stellar
aberration.

To have the distant as a variant make me abit confused about the
arguments in SR. For me it seem impossible for ships travelling
different vectors to have different distances to planet X when passing
a cordinate in space and same for velocities.

I understand that the argument is rather mathematical built on
definitions but invariant distances seem very foreign for me because
it is very hard for me to use my logic exploring the arguments of SR.

I know little/nothing about mathematics but if distances is variant
does it make sense to talk about invariant light paths betwenn frames.

I know you think i am in deep water now, but some features of SR i
have a hard time to analyse by pure logic.

Best regards Jonas Thörnvall



- Randy- Dölj citerad text -

- Visa citerad text -- Dölj citerad text -

- Visa citerad text -

I understand that the argument is rather mathematical built on
definitions but

TYPO invariant *variant*

distances seem very foreign for me because
it is very hard for me to use my logic exploring the arguments of SR.

Jonas Thörnvall wrote:

it is very hard for me to use my logic exploring the arguments of SR.

What have you learned about the subject in the last eight years?

http://groups.google.com/group/sci.p...4657b896fc8e89


---Tim Shuba---

On 22 Feb, 19:20, shuba wrote:
Jonas Thörnvall wrote:
it is very hard for me to use my logic exploring the arguments of SR.

What have you learned about the subject in the last eight years?

http://groups.google.com/group/sci.p...sg/e84657b896f...

---Tim Shuba---

That definitions have higher priority than logic within SR.

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

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

I gave the example above that using the velocity 0.9999c the distance
to earth would have to be 0.01414*300 000 km to earth to make sense
and the distance to the wavefront path would have to be 0.01414*424
264 to actually make sense.

Because the wave path can not be longer than 300 000 km during one
secondn in any frame am i correct?

And the ship only travelled for 0.01414 seconds in the ships inertial
frame. So the distance to the wavefront would differ.(local)

In fact by logic travel in c any distance would shrink to zero using
the formula because no time would pass. And if no time really passed
and the definition is based on how long the wavefront will travel
within a second the actual distance it travelled would shrink to zero
due to the "definition".

Am i correct.

This does not make any sense to me and i think most people using logic
would reject the idea that a distance of 424 264 km actually equals 0
distance just because of the definition.

I think the math of SR is basically correct, i think the postulates is
dependent upon the defintions and that the definitions were made with
"an idea of light velocity being invariant".

So yes i think SR is correct using the definitions of time, length and
distance that was made in the 80's. But i do not think the definitions
has any ground in reality because they were made with an assumption in
mind.

Namely that light propagates invariant in space, and note i agree that
light propagates invariant between frames. I will never though admit
that it propagate invariant in space.

The redefinition was due to the idea that light and radiowaves
propagates invariant in space. How could they if distances is
invariant between frames.

Best regards Jonas Thörnvall

On 22 Feb, 22:08, wrote:
On 22 Feb, 19:20, shuba wrote:

Jonas Thörnvall wrote:
it is very hard for me to use my logic exploring the arguments of SR.

What have you learned about the subject in the last eight years?

http://groups.google.com/group/sci.p...sg/e84657b896f...

---Tim Shuba---

That definitions have higher priority than logic within SR.

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

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

I gave the example above that using the velocity 0.9999c the distance
to earth would have to be 0.01414*300 000 km to earth to make sense
and the distance to the wavefront path would have to be 0.01414*424
264 to actually make sense.

Because the wave path can not be longer than 300 000 km during one
secondn in any frame am i correct?

And the ship only travelled for 0.01414 seconds in the ships inertial
frame. So the distance to the wavefront would differ.(local)

In fact by logic travel in c any distance would shrink to zero using
the formula because no time would pass. And if no time really passed
and the definition is based on how long the wavefront will travel
within a second the actual distance it travelled would shrink to zero
due to the "definition".

Am i correct.

This does not make any sense to me and i think most people using logic
would reject the idea that a distance of 424 264 km actually equals 0
distance just because of the definition.

I think the math of SR is basically correct, i think the postulates is
dependent upon the defintions and that the definitions were made with
"an idea of light velocity being invariant".

So yes i think SR is correct using the definitions of time, length and
distance that was made in the 80's. But i do not think the definitions
has any ground in reality because they were made with an assumption in
mind.

Namely that light propagates invariant in space, and note i agree that
light propagates invariant between frames. I will never though admit
that it propagate invariant in space.

The redefinition was due to the idea that light and radiowaves
propagates invariant in space. How could they if distances is
invariant between frames.

Best regards Jonas Thörnvall

Typo again to much beer

The redefinition was due to the idea that light and radiowaves
propagates invariant in space. How could they if distances is
********variant******** between frames. At least Randy Poe thinks so...


Jonas Thörnvall

Jonas Thörnvall wrote:

On 22 Feb, 19:20, shuba wrote:
Jonas Thörnvall wrote:
it is very hard for me to use my logic exploring the arguments of SR.

What have you learned about the subject in the last eight years?

That definitions have higher priority than logic within SR.

Interesting. Which texts have you been studying?

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

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

Umm, no. Length l is a function of v, yet proper length l' is
independent of v.

http://sv.wikipedia.org/wiki/Bild:L%...ontraktion.png

Same invariants, same universe.


---Tim Shuba---

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

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.

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 earth
although both ship and planet occupied origot 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