Regarding synchronization of the the clocks on the rocket and the clock at 'A' it could be done by a lightsignal sent from a Cephei star system that are sent from a long distanse and perpendicular to the rockets path.

Is your Cephei star system at rest relative to rocket observer or relative to observer A ?
No matter how far away the Cephei system is its simultaniety lines will depend on its movement so Cephei A (at rest relative to A) and Cephei R (at rest relative to rocket) will have different simultaniety lines.

By simultaniety lines here i mean sets of dots of space-time that hold the light once emitted from Cephei at given time moment - that is the light emitted when clock at Cephei was showing given time.

If Cephei is at infinite distance from A and rocket then its simultaniety lines will be parallel to the corresponding observer (which is at rest relative to Cephei) but not to both of them :) so you cant synch clocks of A and rocket - after all their time is flowing at different rate :)

I suggest you to return to the example of throwing muon/rocket at 0.8c speed from A to B ( which are at space-time interval of 8 l.y.) and think about the result once again:

Quote:

What you will see being at point A is that during 18 years of your life the life on the rocket will pass 6 years and cover distance of 8 l.y so when you see rocket arrived at point B the rocket clock will show 6 years passed , the clock at B will show 18 years passed and your clock at A will show 18 years passed. You wonder how is that possible for the rocket to pass 8 l.y distance and having only 6 years passed onboard ?

Have in mind however that rocket observer could tell the same about A or B.
For him it is A and B moved 4.8 l.y. in 3.6 years time
So the space contraction and time dilation is not real but is rather our attempt to see the world as if it was simultanious with us infinite 3D space.

So if we want to see the real world as if it was simultanious with us 3D space the Special Relativity sugests the following explanation of the experiment results:
rocket moving at 0.8c has its time slowed and space contracted by 60% (this is as seen from observer A or B)
So the distance AB contracted from 8 l.y to 4.8 l.y. (=8*60%/100%)
rocket traveling at 0.8c speed covered 4.8 l.y. distance in 6 (=4.8/0.8)its own years which when converted to our time gives us 10 years (=6*100%/60%) in accordance with time required to cover 8 l.y. at speed of 0.8c.

Is your Cephei star system at rest relative to rocket observer or relative to observer A ?
No matter how far away the Cephei system is its simultaniety lines will depend on its movement so Cephei A (at rest relative to A) and Cephei R (at rest relative to rocket) will have different simultaniety lines.

Every expriment you make will be affected with a amont of error. In this case the differense in time the starlight is observed should be neglect.

Quote:

By simultaniety lines here i mean sets of dots of space-time that hold the light once emitted from Cephei at given time moment - that is the light emitted when clock at Cephei was showing given time.

If Cephei is at infinite distance from A and rocket then its simultaniety lines will be parallel to the corresponding observer (which is at rest relative to Cephei) but not to both of them :) so you cant synch clocks of A and rocket - after all their time is flowing at different rate :)

Yes, but that is not an isue regarding synchronisation.

the differense in time the starlight is observed should be neglect.

the differense does not depend on distance to Cephei as much as on its relative speed.
When distance is big the difference almost do not depend on distance but it keeps to depend on relative speed regardless of distance

Quote:

that is not an issue regarding synchronisation.

It is an issue because when Cephei is moving relative to you it means the light signals it issues are placed in space-time differently.

In case of no relative motion time moments in space-time will look:
0 0 0 0 0 0
1 1 1 1 1 1
2 2 2 2 2 2
3 3 3 3 3 3

in case of relative motion time-moments will look somewhat like this:
0 0 1 1 2 2
1 1 2 2 3 3
2 2 3 3 4 4
3 3 4 4 5 5

I don't know how to make it more obvious , sorry :)

## RE: Regarding

)

Is your Cephei star system at rest relative to rocket observer or relative to observer A ?

No matter how far away the Cephei system is its simultaniety lines will depend on its movement so Cephei A (at rest relative to A) and Cephei R (at rest relative to rocket) will have different simultaniety lines.

By simultaniety lines here i mean sets of dots of space-time that hold the light once emitted from Cephei at given time moment - that is the light emitted when clock at Cephei was showing given time.

If Cephei is at infinite distance from A and rocket then its simultaniety lines will be parallel to the corresponding observer (which is at rest relative to Cephei) but not to both of them :) so you cant synch clocks of A and rocket - after all their time is flowing at different rate :)

## I suggest you to return to

)

I suggest you to return to the example of throwing muon/rocket at 0.8c speed from A to B ( which are at space-time interval of 8 l.y.) and think about the result once again:

Have in mind however that rocket observer could tell the same about A or B.

For him it is A and B moved 4.8 l.y. in 3.6 years time

So the space contraction and time dilation is not real but is rather our attempt to see the world as if it was simultanious with us infinite 3D space.

So if we want to see the real world as if it was simultanious with us 3D space the Special Relativity sugests the following explanation of the experiment results:

rocket moving at 0.8c has its time slowed and space contracted by 60% (this is as seen from observer A or B)

So the distance AB contracted from 8 l.y to 4.8 l.y. (=8*60%/100%)

rocket traveling at 0.8c speed covered 4.8 l.y. distance in 6 (=4.8/0.8)its own years which when converted to our time gives us 10 years (=6*100%/60%) in accordance with time required to cover 8 l.y. at speed of 0.8c.

## sadly we will not see an

)

sadly we will not see an empiric experiment in the near future.

## RE: Is your Cephei star

)

Every expriment you make will be affected with a amont of error. In this case the differense in time the starlight is observed should be neglect.

Yes, but that is not an isue regarding synchronisation.

## RE: the differense in time

)

the differense does not depend on distance to Cephei as much as on its relative speed.

When distance is big the difference almost do not depend on distance but it keeps to depend on relative speed regardless of distance

It is an issue because when Cephei is moving relative to you it means the light signals it issues are placed in space-time differently.

In case of no relative motion time moments in space-time will look:

0 0 0 0 0 0

1 1 1 1 1 1

2 2 2 2 2 2

3 3 3 3 3 3

in case of relative motion time-moments will look somewhat like this:

0 0 1 1 2 2

1 1 2 2 3 3

2 2 3 3 4 4

3 3 4 4 5 5

I don't know how to make it more obvious , sorry :)

## RE: It is an issue because

)

Yes. But as long as the path, 'A' 'Rocket', is perpendicular to the direction to the star i should affect both system equally.