Hi Guys,
Just had an amusing thought about SRT and how this may make an interesting gendanken for those who are pssionate about A.E.s SRT

We have three ships in space. all traveling at relative V
they are all connected together by a a piece of string long enough to accomodate the various distances involved.

Think about it for a bit and show that time is relative? [ the rate of time may be relative due to dillations but the present moment for all ships must be the same moment [ absolute] or the string must time travel as some stage along it's length.
http://bizzymate.com/uploads/images/diag/diag03.gif
please excuse the scribble...

maybe this is crazy but hey...what the hell...

Well, the idea behind special relativity is that reference frames only make sense if they're point-like. (This is something that a poster called zanket never realized.) This means that at each point along the string, you can define a good coordinate frame, but you cannot define a good coordinate frame for ``the string'' as a whole.

So the resolution is that you are not considering the fact that the string is an extended object, and therefore you need multiple reference frames to describe it.

Well, the idea behind special relativity is that reference frames only make sense if they're point-like. (This is something that a poster called zanket never realized.)

Either you mean something other with point-like than I think, or I'm missing something: A reference frames gives coordinates to all events in spacetime.

It makes perfect sense for me to give coordinates to something that isn't centered on me...

A reference frames gives coordinates to all events in spacetime.This is confusing. How can a reference frame give coordinates for all point-events in spacetime? This runs counter to all that is known about both special and general relativity. Specifically, the default would be that, to each point-event in spacetime, the maximum necessary reference frame is the point itself; it may be "larger", but it need not.

Also, if you care, and more significantly, it is also counter to the general construction of manifolds. (Unless, of course, you think that spacetime is not a manifold as classically defined)

Which I have tried to explain elsewhere......

A reference frames gives coordinates to all events in spacetime.

QuarkHead is correct---there is no one coordinate frame that can cover an entire manifold.

And, reading back on my response, I should have said that OBSERVERS have to be point-like, and an observer defines a reference frame. What each observer sees depends on his reference frame---so Observer A looking at some arbitrary point B on the rope sees something different than an observer living at point B does when he looks to point A.

This is confusing. How can a reference frame give coordinates for all point-events in spacetime? This runs counter to all that is known about both special and general relativity.

So you're saying that for a given reference frame there are events that cannot be given coordinates in that reference frame?
QuarkHead is correct---there is no one coordinate frame that can cover an entire manifold.

God, I hated differential geometry...

And, reading back on my response, I should have said that OBSERVERS have to be point-like, and an observer defines a reference frame. What each observer sees depends on his reference frame---so Observer A looking at some arbitrary point B on the rope sees something different than an observer living at point B does when he looks to point A.
Sure, that's not contested.

[Edit: Actually, rereading that last response, I was being overly strict in my reading of your first post. Please ignore my tired, confused babble...]

say the rope is made of copper strands and is used as an intercom system between ships. would it work?
sending messages into the future sounds like a great idea... or even more intiguing: what if the rope had a fillament of optical fibre...would it work?
I tend to to think that SRT would force our optic fibre transmissions to have variable light speed as the info travellled back and forth along the rope or cable.
Arguing that the optical fibre at any given point become an specific reference frame thus maintaining invariance of light.
But given that we are talking about infinitely small divisions of points along the cable this seems like an absurd proposition and another example of just how far we as rational beings will go to accomodate photon theory.

The bottom line of course is that regardless of theory the ships are connected by a cable or rope whilst traveling at relative V.
According to SRT this connection bridges the gap between relative time lines. A bit like a father writing to his son before the father is born.

So you're saying that for a given reference frame there are events that cannot be given coordinates in that reference frame?

God, I hated differential geometry...Well, I'm sorry to hear that, I think it's rather fun, at least on a superficial level. As it's my day off, lemme try and explain to all what's going on here.

We will think of spacetime as a manifold. We only need to know that this means it is always possible to choose coordinate "neighbourhoods" that are indistinguishable from "flat" spacetime in the Euclidean sense.

Recall that a point in spacetime, in our manifold, is an event. We now need to know exactly what we mean by saying 2 such points are the same or different. For this we will need what's called a separation axiom. The only such axiom that is not in some sense pathological is the so-called Hausdorff property; for any pair of points x \ne y, I can always choose coordinate neighbourhoods X \ni x,\; Y \ni y such that X \cap Y = \emptyset. This is by definition.

Then, for x and y to talk meaningfully about their spacetime vectors is impossible, since, simply by virtue of their neighbourhoods being disjoint, there can be no coordinate transition function X \to Y.

Let us now introduce a third point z, and choose an arbitrary neighbourhood Z \ni z, such that x,\; z \in X \cap Z. Now these 2 guys can compare spacetime vectors by means of the transition function \sigma: X \to Z which maps each coordinate set onto to the other.

But, by Hausdorff, I can still find a neighbourhood Z' \ni z such that X \cap Z' = \emptyset, and we're back to square one!

Yeah, OK, that was so rough-and-ready as to be nearly wrong (but not quite!)

Well, I'm sorry to hear that, I think it's rather fun, at least on a superficial level.

Horses for courses, no doubt. I simply found algebra (plus logic and discrete math) more fun, which probably has quite a lot to do with why I became a computer scientist instead of a mathematician.

<lots of stuff>

Did I mention topology wasn't my favourite, either? I did enjoy large parts of Munkres' "General Topology", but sometimes it just got crazy (and crazy difficult, usually) with no warning.

In any case, your exposition above tells me that spacetime is Hausdorff (i.e. separable), but I'm having difficulty seeing how that matters.

Maybe I'm confused, but I usually think of reference frames in special relativity as each being \mathbb{R}^{1,3} and related by Lorentz transforms. Not as being subspaces of some "overall" Minkowski spacetime (which seems rather too much like an "absolute reference frame" sort of thing to me). That you shouldn't be able to transform some points in one frame to points in other frames doesn't really match up with that view.

Oh, and I might add the caveat that I haven't actually studied relativity formally (a few weeks during high school physics hardly counts), so I could very well be fundamentally mistaken about this.

The bottom line of course is that regardless of theory the ships are connected by a cable or rope whilst traveling at relative V.
According to SRT this connection bridges the gap between relative time lines. A bit like a father writing to his son before the father is born.

This is based on a misunderstanding of SR. Because the signal along the wire has a finite speed (namely, speed of light) in ANY reference frame, one cannot ``send a message into the future''.

In any case, your exposition above tells me that spacetime is Hausdorff (i.e. separable), but I'm having difficulty seeing how that matters.

Maybe I'm confused, but I usually think of reference frames in special relativity as each being \mathbb{R}^{1,3} and related by Lorentz transforms. Not as being subspaces of some "overall" Minkowski spacetime (which seems rather too much like an "absolute reference frame" sort of thing to me). That you shouldn't be able to transform some points in one frame to points in other frames doesn't really match up with that view. Oh well, I must not have expressed myself quite as well as I might have wished. Lemme try again:

The domain of the Special Theory is Euclidean 4-space , i.e. "flat" in some sense. But, thinking of spacetime as a manifold, we have no reason to assume it is globally flat, in the same sense (this was Ben's earlier point). This seems to imply that the Special Theory is a local theory, as indeed it is

But we do know this nice thing about our spacetime manifold, that we may consider it to be locally Euclidean for any arbitrarily chosen coordinate "patch". And provided only that this patch is non-empty (it never is, of course), we will call it a neighbourhood of some point therein.

Then we may think of the Lorentz transformation as being a coordinate transformation between such neighbourhoods, which I earlier called "transition functions". As I tried to explain, obviously rather poorly, this can only be possible if, for some pair of neighbourhoods, the intersection is not empty. This is how transition functions work, as I am sure you know.

But the Hausdorff property always allows me to choose a pair of non-identical points such that the intersection 0f their neighbourhoods is empty. Thus, no transition functions can possibly exist that sends the coordinates of one to the coordinates of the other - no Lorentz.

It simply remains to assert that, even though any 2 points chosen at random can be "Hausdorffed", the Hausdorff property in no way insists that the neighbourhood of x contains only x. In fact, in general we know this is not the case.

So, the Special Theory holds locally, but not globally.

Umm, I have drink taken, I hope this is clear?

This is based on a misunderstanding of SR. Because the signal along the wire has a finite speed (namely, speed of light) in ANY reference frame, one cannot ``send a message into the future''.
but at least at some point along the cable the message must alter it's time line yes? Otherwise light speed would become variant instead of invariant?

but at least at some point along the cable the message must alter it's time line yes? Otherwise light speed would become variant instead of invariant?
Yes, it does. Different parts of the string will experiance different tick rates according to some external observer. To demonstrate this: coil a string and lay it on the ground, then grab an end and walk with it. Notice how parts of the coil lay stationary, while other parts move with you? (you are slowly pulling slack off the coil.)
For simple calculations, you can treat the part of the coil that is motionless as one referance frame, and the part that you are pulling on as another. The place where the slack is being consumed is where the referance frames switch.

-Andrew

Yes, it does. Different parts of the string will experiance different tick rates according to some external observer. To demonstrate this: coil a string and lay it on the ground, then grab an end and walk with it. Notice how parts of the coil lay stationary, while other parts move with you? (you are slowly pulling slack off the coil.)
For simple calculations, you can treat the part of the coil that is motionless as one referance frame, and the part that you are pulling on as another. The place where the slack is being consumed is where the referance frames switch.

-Andrew
what I meant by time line was that parts of the string would be in the future or past of other parts of the string.
So a message must be traveling through time and not just with time.

what I meant by time line was that parts of the string would be in the future or past of other parts of the string.

No. Each section of the string has it's own world line.

No. Each section of the string has it's own world line.
ahh of course a global reference frame is not allowed under SRT...

so even though the message may be traveling into the future it aint because srt dis-allows it.
hmmmm......but still the ships are connected are they not?
Or are you saying that the ships are not connected somehow even though the rope or cable or string connects them.

Sort of like having your cake and eating it simultaneously...IMO

so even though the message may be traveling into the future it aint because srt dis-allows it. It's no more travelling into the future than a man is on his way to work.

-Andrew

if for a moment I declare I have no knowledge of SRT and I tether three ships together with the cable as described why would I accept that each ship observer has his own unique world view when obviously they are connected to my world view by way of the tethered cable.
How would you prove that they would have a different world view?

In other words why should I believe that SRT is correct in this case?

I know ultimately that it is the view that light speed must be held invariant that eventually leads to the notion that this is proof.

For light speed to be invariant SRT must be true is the final assessment IMO.

Provocative role playing:
But given that I do not believe in the existance of photons I still await evidence to support SRT main premise or postulation.
Given that the postulate of lights invariance and therefore photons existance leads to a situation where by the universal constant of inertia and gravity is invalidated.
This means that gravity and inertia are constants only to a unique world view but relative to all other world views.
I fail to see why I should accept this notion especially as it is unable to be proved due to the nature of SRT's unique perspectives for all observers.
So I guess I shall stick to that which makes more sense and look for a way of describing the data and effects we experience that are currently poorly explained using SRT and photon theory.

Let me ask you:
What is the difference between 2 ships connected by a string (or fiber optic cable), and 2 ships communicating via radio transmission?

The radio is faster, easier, and won't break as easily.
Otherwise, one can think of the string as a large number of radio transmitters, each staying in contact via exchange of virtual photons (holding the molecules together,) just as the radio transmissions exchange photons.

-Andrew

Otherwise, one can think of the string as a large number of radio transmitters, each staying in contact via exchange of virtual photons (holding the molecules together,) just as the radio transmissions exchange photons.

This is a very good way to see things.

Andbna:

Let me ask you:
What is the difference between 2 ships connected by a string (or fiber optic cable), and 2 ships communicating via radio transmission?

Virtual photons are exchanged at the speed of light. Light is invariable. Thus the string would remain invariable in all reference frames when judged like this.

Quantum Heraclitus:

I believe that SRT would postulate that each ship would measure the string differently in relation to its speed. That is to say, that even matters such as distance and size (but not mass or the speed of light) would be variable at different speeds.

Let me ask you:
What is the difference between 2 ships connected by a string (or fiber optic cable), and 2 ships communicating via radio transmission?

The radio is faster, easier, and won't break as easily.
Otherwise, one can think of the string as a large number of radio transmitters, each staying in contact via exchange of virtual photons (holding the molecules together,) just as the radio transmissions exchange photons.

-Andrew

The reason why the cable is important rather than using light or other EM is that the cable is provable as mass.
The cable is a material connection between all ships regardless of velocity.

The issue is about non-simultaneity as required by SRT for relative v RF's
Non-simultaneity must state that all ships are in a different world time line and none are together in a single dynamic present moment. It states that all ships must be simultaneously in a different world time line or differnet "NOWs" [present]

The string or cable either travels towards the future or the past but is still connected to each ship so the signal sent must by virtual of this SRT fact be travelling likewise.
IN fact all three ships could actually share the same flight path and actually be superimposed with each other and yet they would not collide or even notice the other ship is in the same location.
This is because the location is now made up of non-simultaneous NOWS so therefore neither ships observers NOW is observable from the other ships.
If three ships were programed to collide at a given point between two inertial stars using different vectors and velocities would they collide according to SRT.
In fact that would make a great gendanken....hmmmmm

How would you get three ships to collide simultaneously at a given point between two inertial stars if each ship is given a different vector and relative Velocity to each other and the stars in question?
The collision event must be a simultaneous NOW for all three ships and the stars.

Quantum Heraclitus:

I believe that SRT would postulate that each ship would measure the string differently in relation to its speed. That is to say, that even matters such as distance and size (but not mass or the speed of light) would be variable at different speeds.
I think you are correct that this would be the SRT position.

The domain of the Special Theory is Euclidean 4-space , i.e. "flat" in some sense. But, thinking of spacetime as a manifold, we have no reason to assume it is globally flat, in the same sense (this was Ben's earlier point). This seems to imply that the Special Theory is a local theory, as indeed it is

Ah, see, there's the rub - I was simply thinking of R^4, not manifolds in general. Then everything makes a lot more sense.

Thanks for the (snipped) explanations, and patience.

Virtual photons are exchanged at the speed of light. Light is invariable. Thus the string would remain invariable in all reference frames when judged like this.

A better way to say this is that photons would take the shortest path between the ships. If they are constrained to travel along the wires, then they can no longer take the shortes path.

Quantum Quack---I think you are more or less completely confused about what you are saying.

funkstar, you're welcome. In fact we can model the special theory on R^4 to show something rather wonderful. Let me first give a definition. Suppose I choose a coordinate system for some test particle A such that it has zero displacement on spatial axes. I will call this the state of being "at rest", though this is an abuse, since we can never be at rest w.r.t the time axis (sadly).

I will call a coordinate system an inertial frame if, for any material particle B in uniform motion relative to A, there is a coordinate transformation that will bring B to rest in it's own coordinate system. This transformation will, of course, be Lorentz.

Now for simplicity let's only consider displacements on the x spatial axis, and call our space R^2. Since this is a flat space, we can assume that R^2 = (t,x) is our inertial frame. Assume that A is at rest in this frame.

Now consider a time-dependent displacement of A on the x-axis i.e. A has unifom velocity relative to R^2. It is easy to see that A', as we now call it, can be brought to rest by a rotation about the origin R^2 \to R^2'. Thus, Lorentz is realized as a coordinate rotation.

And for as many different velocities as I care to consider, there will be a corresponding R^2_i given by the Lorentz rotation, where each of these different R^2_i's is each isomorphic to each other and to R^2.

But this is just the definition of a manifold! So the set of Lorentz transformations is a manifold.

Moreover, since any 2 or more consecutive rotations is again a rotation, and since the rotation r followed by the rotation -r is equivalent to the zero rotation, the Lorentz set is a group.

So the set of Lorentz transformations is a manifold and also a group. This is the definition of a Lie group!!!

Incidentally you can use my definition of an inertial frame above to easily show that the so-called Twin Paradox is not a paradox, has nothing to do with acceleration, and most certainly nothing to do with General Relativity.

Gosh, look at the time. I gotta run...

Bentheman:

A better way to say this is that photons would take the shortest path between the ships. If they are constrained to travel along the wires, then they can no longer take the shortes path.

Correct, but it could only do so at the speed of light.

This actually makes an interesting thought experiment:

Would a string of fiber optic cable force all the ships into the same reference frame? As any signal from either ship would be visible to all the others and would have to be reported precisely the same due to the constant nature of C...

Quantum Heraclitus:

I think you are correct that this would be the SRT position.

To be quite honest, I have no idea what SRT would predict int erms of spatial dilation on the string from speed and such.

Virtual photons are exchanged at the speed of light. Light is invariable. Thus the string would remain invariable in all reference frames when judged like this. (For QQ as well: )
Yes, the virtual photons are exchanged at light speed, but that means that the minimum time for any 'signal' (be it a movement of the end piece,an electron being added to the end of the wire, etc...) takes a minimum time of t=L/c to propogate from one end to another, where L is the length of our string.
Because of this, the ends will not 'know' about what's happening at the other instantaniously, which is the entire point.

This is in contrast to a standard rigid body, in which we assume that forces, velocities, etc... affect the entire body at the same time. Ultimatly, even if we used an iron rod instead of a string, we must remember that it too is a softbody, with it's atoms of iron being rigid body portions. While we may approximate it as a rigid body in most cases, we cannot use this approximation on a very long rod and expect useable resaults, anymore than we can approximate the energy requried to get an object travelling at 0.9c using Newtonian mechanics.

This means that if an acceleration is applied to one end of the string, it will not be felt by the other for L/c amount of time, so for sufficiently long string, there can easily be periods in which some of our 'radio transmitters' are accelerating while the others are still at rest, and as such, we will observe some of them to have slower tick rates than others.
Hence, we must recognize the string as a softbody composed of neumerous individual objects which do not necessarily share a referance frame.

The reason why the cable is important rather than using light or other EM is that the cable is provable as mass.
The cable is a material connection between all ships regardless of velocity. My 2 radio transmitters have mass, and they represent a physical connection between the ships just as much as the string does (albiet, much much weaker, but a cable won't stand up to a rocket engine anyways.)
They also simplify calculations :)

The string or cable either travels towards the future or the past but is still connected to each ship so the signal sent must by virtual of this SRT fact be travelling likewise. Right, some transmitters on the way are travelling at a different velocity than others. Not much different than bouncing a radio signal off a satelite orbiting earth (signal originated from a ground station) in order to communicate with a Mars lander.

How would you get three ships to collide simultaneously at a given point between two inertial stars if each ship is given a different vector and relative Velocity to each other and the stars in question? If 2 (or more) events occur at the same time and position relative to some observer, they occur at the same time and position relative to any observer.

-Andrew

If 2 (or more) events occur at the same time and position relative to some observer, they occur at the same time and position relative to any observer.
Doesn't this mean that for the two or more ships to share the same event at the same time and location must also share the same world time line to do so?
btw thanks for taking the time to post.

Would a string of fiber optic cable force all the ships into the same reference frame? As any signal from either ship would be visible to all the others and would have to be reported precisely the same due to the constant nature of C...

No I don't think so. Any signal along the wire must propogate at a speed less than or equal to c. You're just describing a ``perfect telephone''!

From what I understand the issue of a fibre optic cable joining 3 ships has posed some interesting thoughts.
The one that intrigues me the most at present is that if light speed is invariant it can only be deemed so over a given distance.
Now if we assume that the cables velocity is variable from one end to the other as some of the cable is in another reference frame and the rest is somewhere in between then how could we say that lights speed in invariant when the distances needed for that invariants can become infinitely divisible and microscopic.

As the cable takes up the velocity of one of the RF the cable must progressively speed up along it's length in a form of acceleration. I guess.

So maybe the answer lies in how an accelerating RF is viewed.
However where I think it gets complicated is that for light speed to be invariant it must have a distance to travel with in an inertial frame...am I mistaken?
And if the cable cannot be broken down into relative inertial frames as the velocity and vector even, may be an infinite gradient, then how can the light speed be deemed invariant?
sheesh ! hard to put into words...

Another possible scenario could be that Ship B is connected to Ship A by way of a winching cable rolled up inside Ship A
As ship B 's relative v is say .6c the cable exiting Ship A has a velocity of .6 c
So a message is sent to Ship B along this cable that has a v or .6 c to reach the ship also at v=.6 'c'
Say the cable is not undergoing any acceleration.

The light message is sent via this cable to ship B

how would this be handleed by SRT? I wonder?

I think we would still have a signal of light travelling into the future as the issue of non-simultaneity is intractible.
But it would be in that future immediately the signal acquired the cables velocity of .6c to maintain invariants.

Bentheman:

No I don't think so. Any signal along the wire must propogate at a speed less than or equal to c. You're just describing a ``perfect telephone''!

I do believe that all relations to C are held the same in all reference points, regardless of whether C is at all slowed down.

Don't quote me on that.

In fact, let's see if anyone knows whether that is the case fully.

Andbna:

(For QQ as well: )
Yes, the virtual photons are exchanged at light speed, but that means that the minimum time for any 'signal' (be it a movement of the end piece,an electron being added to the end of the wire, etc...) takes a minimum time of t=L/c to propogate from one end to another, where L is the length of our string.
Because of this, the ends will not 'know' about what's happening at the other instantaniously, which is the entire point.

This is in contrast to a standard rigid body, in which we assume that forces, velocities, etc... affect the entire body at the same time. Ultimatly, even if we used an iron rod instead of a string, we must remember that it too is a softbody, with it's atoms of iron being rigid body portions. While we may approximate it as a rigid body in most cases, we cannot use this approximation on a very long rod and expect useable resaults, anymore than we can approximate the energy requried to get an object travelling at 0.9c using Newtonian mechanics.

This means that if an acceleration is applied to one end of the string, it will not be felt by the other for L/c amount of time, so for sufficiently long string, there can easily be periods in which some of our 'radio transmitters' are accelerating while the others are still at rest, and as such, we will observe some of them to have slower tick rates than others.
Hence, we must recognize the string as a softbody composed of neumerous individual objects which do not necessarily share a referance frame.

You are correct that there are multiple reference frames to be addressed in a string as you've stated. But that being said, as we're dealing with time=l/c, with c being invariant in all reference frames, then it would seem every reference frame in the string would report light the same way, and of course, those people at the end of the strings.

Let's also assume that at any point the observers on the spacecraft can see the light travelling down the string/fiber optic cable (let's switch to the latter as it seems to make this a lot more interesting). If that is the case, and again no reporter is going to ever disagree on C, then it would seem everything would share a single isntance, violating the fact that they ought to be in a different reference frame.

I do believe that all relations to C are held the same in all reference points, regardless of whether C is at all slowed down.

Well, c can never be ``slowed down'', as this violates the first postulate (c is always the same in all reference frames).

BenTheMan:

I should have said "the beam of light".

Scientists have been able to slow down light to a few miles an hour by trapping it in dense clouds of gas and such.

Doesn't this mean that for the two or more ships to share the same event at the same time and location must also share the same world time line to do so?
btw thanks for taking the time to post. No, not exactly. It merely means that thier 3 worldlines must each intersect at one point.
When they do collide, if we assume the cockpits all join together (and ignor the debris jettisoned in the collision,) then what we have is 1 ship which can now be treated as one referance frame.

Now if we assume that the cables velocity is variable from one end to the other as some of the cable is in another reference frame and the rest is somewhere in between then how could we say that lights speed in invariant when the distances needed for that invariants can become infinitely divisible and microscopic. Well, truly, it's no suprise that we need to calculate time dilation at the atomic level. I can cut the cable into atoms no? Each atom, on it's own would be it's own referance frame. When assembled as a cable, there isn't anything real that makes it's referance frame merge with that of the other frames of the cable.
We, as humans, merge them to simplify calculations, because it usualy produces resaults that are accurate eanough for our purposes.
This is where the concept of rigid, versus soft bodies comes into play. A perfect rigid body is 1 pure structure; an entire macro-referance frame. It does not exist in reality (even a steel cube is still composed of atoms, and it can be deformed with a strong eanough force,) but again, it simplifies calculations.
Soft bodies however can move relative to each other. Generaly we only deal with thier relative movements on a newtonian scale (too small to account for relativity,) again to simplify calculations.
Now, a softbody which is moving relativisticaly relative to itself (as the string between the rockets) defies our usual methodes of simplification. At this point, it's best to devide the string into sections which are moving approximatly the same speed and treat them as individual referance frames.

In conclusion: the real question is not "why can we devide the string into inumerous small referance frames?" but "how can we unite these inumerous small referance frames for the purpose of simplicity?"

Let's also assume that at any point the observers on the spacecraft can see the light travelling down the string/fiber optic cable (let's switch to the latter as it seems to make this a lot more interesting). If that is the case, and again no reporter is going to ever disagree on C, then it would seem everything would share a single isntance, violating the fact that they ought to be in a different reference frame. Light travels at c always, but the clock rates are not constant. Hence, different observers will observe others to be suffering from some time dilation. Even ends of the fiber optic will, though it may not be relevant for calculating the time it takes for the signal to come out one end.

Anyway, my enitre point being: what you shove in one end of a cable doesn't come out the other for some time.


Excuse me if this post lost coherancy near the end, and sorry I can't address your other post QQ; it's getting late.
-Andrew

Andrew:

Light travels at c always, but the clock rates are not constant. Hence, different observers will observe others to be suffering from some time dilation. Even ends of the fiber optic will, though it may not be relevant for calculating the time it takes for the signal to come out one end.

No problemo on the coherence, I understood enough.

Now let's talk about the clocks in relation to the light beams.

Clearly SRT puts forth the idea that clocks will run at different rates at different speeds and time itself dilates from such.

However, none of the observers, no matter how slow or fast their clocks are going, will ever disagree on how fast the light is going. An observer stationary compared to one at 1/3rd C and 1/2 C will both accurately talk about the light beam. Accordingly, it is an absolute, and therefore...it would seem all could pinpoint the exact same time, despite being in different refrence points.

Quantum Quack---I think you are more or less completely confused about what you are saying.

Most probably the case Ben. most probably...

One of the reasons for persisting with SRT issues is that years ago a physics and maths professor form Russia was given the task of calculating the issue of non-simultaneity and how this would effect collisions on a moving object.
Half way through his task he was very upset with his conclusions having been a proponent of SRT for most of his working life. He then withdrew from the task with out further word.

The gendanken was using the orbit of Jupiter as the moving target and have three comets traveling at different speeds for over 20million years and how these commets could possibly collide with jupiter in orbit around our sun.

The issue of simultaneity is whether the distance between world time lines of relative v reference frames continues to grow according to time relative to each other.

The scientist in question probably discovered that due to galactic rotation one of the comets would not even come close to Jupiter yet suffer a collision with it.

If we have two ships moving at significant relative v how fast does the separation between world time lines grow?
And if from 29 billion years ago relative v RF have existed how can we make any sense of our universe at all given that after 29 billion years the universe would be indescernable or at least very different to each obeserver...?

So it seems that to prove SRT Invalid one has to do the complex maths required as our physics prof attempted to do...push the theory to the extremes and provide your conclusions. As I do not have the sophisticated math required to do the task I have to leave that to someone else who can. If ever they want to spend that sort of time and energy.