[mad aetherist (OP)]

Comment. No i dont see the thread snapping. Unless u mean from the g force of acceleration.

Length contraction of the ships will cause the thread to break on acceleration. The ships maintain the same distance between the centres of mass of each, but because they both contract in length, the thread will snap. This happens both in LET (Lorentz Ether Theory) and in SR.

If they resynchronise their clocks after accelerating and do so on the basis that they're now stationary, they'll end up with the leading one running behind the other (when observed by a stationary observer in the original frame). That's why the leading one will start decelerating after the trailing one, but they will see themselves as simultaneously beginning that deceleration. If they don't resynchronise their clocks though, the leading ship will not start the deceleration late, and to the people in the two ships it will appear as if the leading one starts its deceleration first.

Comment. Wow, if thats the Einsteinian answer then Einsteinians are crazier than i ever thort. I dont see how X or Y can ever see the thread snap in the Einsteinian universe -- X & Y must always think themselves to be stationary relative to each other.

They are stationary relative to each other, but you make a good point - as they accelerate, the lead one will appear to accelerate faster than the trailing one from the point of view of the people in those two ships because the apparent distance between them will increase. The leading one will also appear to stop accelerating sooner while the trailing one appears to continue accelerating until it's up to the same speed, and yet both of them accelerated at the same rate for the same length of time. When they decelerate, if they do this without resynchronising clocks, the trailing one will appear to start its deceleration first (from the point of view of the people in those two ships) and then the leading one will appear to decelerate more strongly, and yet again the reality is that they both started their deceleration at the same time and decelerated at the same rate. This is again an LET description, but it takes you straight to the correct SR description too - it's much harder to work out what would happen if you only know SR because it's so easy to misunderstand the rules in SR. Your idea that the ships should appear to remain stationary relative to each other under acceleration from the point of view of the occupants in SR is incorrect.

And i dont see how O might see the thread snap.

The thread either snaps or it doesn't. If it snaps and O can't see it, O needs to buy a bigger telescope.

I get it that Einsteinian SR says that if X & Y are simultaneous in their frame then they cannot be simultaneous in any other frame (this rule is wrong)(but i can follow their logic)(albeit flawed). Thusly O will see a difference in activity of X compared to Y, but the thread doesnt snap in the XY frame, therefore the thread doesnt snap, therefore O cannot see the thread snap (still sticking to Einstein's SR rules in an Einstein universe). Anything else is batshit crazy. [/color]

There is no question of the thread snapping for some observers and not for others - no theory of relativity allows that. The thread will always snap if the acceleration starts at the same time for leading and following ship with clocks synchronised for the frame in which they begin from at rest. If they synchronise the clocks in advance for the target frame in which they'll be at rest once they've stopped accelerating, then the thread will go slack instead. If they start with the clocks synchronised for a frame half way in between and start with a slack line with just the right amount of slack in it, it could become tight half way through and then go slack again. This applies equally for LET and SR.

Yep, i dont understand SR & GR. Re LET i agree that the thread might snap, & that the distance tween center of mass of X & Y doesnt change etc, all of that is common sense. But in SR & GR space along any one line must contract etc evenly & equally along every point along that line, to infinity. Hencely if X contracts then so does Y & so does the string & so does space, hencely the string doesnt snap.

In addition nothing in SR or GR is real, hencely there can be no contraction of any sort anywhere, therefore the string doesnt snap.

In addition observer O might see an apparent change in velocity or position or length of X & string & Y, if that is what the rule dictates, & this might require that the string snap & be seen to snap, but the real string is not bound to actually do what O is bound to see. O will not see the string snap, because it doesnt snap.

Einstein's gamma is merely a math-trick to ensure that the speed of light is isotropic in all frames. But the resulting changes in length ticking etc are not real. Hencely not being real this allows the lengths tickings etc to be different for different observers. If they can be different in that way then clearly they are not real changes. Which begs the question what use is SR & GR. The answer is that they give good numbers for some realworld happenings. But u shoodnt then peer into any & every little baby interim term etc & say that that baby is itself real & any associated baby number good just because the big adult end term is a goodish number.

[Halc]

If they start with the clocks synchronised for a frame half way in between and start with a slack line with just the right amount of slack in it, it could become tight half way through and then go slack again.

A nit correction: Other way around.  It could be tight at first, and gets slack as the two ships approach the frame in which their clocks are synchronized, and then get tight again at the end.

Yep, i dont understand SR & GR. Re LET i agree that the thread might snap, & that the distance tween center of mass of X & Y doesnt change etc, all of that is common sense.

Well since both theories make the same predictions, SR will also predict the thread breaking then.

[mad aetherist (OP)]

If they start with the clocks synchronised for a frame half way in between and start with a slack line with just the right amount of slack in it, it could become tight half way through and then go slack again.

A nit correction: Other way around.  It could be tight at first, and gets slack as the two ships approach the frame in which their clocks are synchronized, and then get tight again at the end.

Yep, i dont understand SR & GR. Re LET i agree that the thread might snap, & that the distance tween center of mass of X & Y doesnt change etc, all of that is common sense.

Well since both theories make the same predictions, SR will also predict the thread breaking then.

No i dont think that i ever said that both make the same predictions. My understanding is that Lorentz relativity says that only objects contract, space does not contract (string stretches or slackens depending on aetherwind). Whereas Einstein says that space contracts, & everything in that space contracts in sympathy with the space (string never stretches nor slackens).

[Halc]

No i dont think that i ever said that both make the same predictions.

You probably didn't say that, but I did.  If your theory is different than standard neo-Lorentz theory, then perhaps your personal theory makes different predictions than either of them.

Whereas Einstein says that space contracts, & everything in that space contracts in sympathy with the space (string never stretches nor slackens).

You're misinterpreting Einstein.  He says something like that in context of different frames, but you're considering the distance between X and Y in O's frame, and the space between them never changes in that frame since they're doing identical things at the same time.

In the accelerating frame of X or Y, Y is moving sooner than X, increasing the distance between them and breaking the string.

[mad aetherist (OP)]

No i dont think that i ever said that both make the same predictions.

You probably didn't say that, but I did.  If your theory is different than standard neo-Lorentz theory, then perhaps your personal theory makes different predictions than either of them.

Whereas Einstein says that space contracts, & everything in that space contracts in sympathy with the space (string never stretches nor slackens).

You're misinterpreting Einstein.  He says something like that in context of different frames, but you're considering the distance between X and Y in O's frame, and the space between them never changes in that frame since they're doing identical things at the same time.

In the accelerating frame of X or Y, Y is moving sooner than X, increasing the distance between them and breaking the string.

Thats the bit i dont understand, how one can start accelerating before the other (X is in front so if X starts first then the string might snap)(u said Y starts first).

[Halc]

Thats the bit i dont understand, how one can start accelerating before the other (X is in front so if X starts first then the string might snap)(u said Y starts first).

I guess the OP was vague about this.  I thought "Y(line ahead)" meant that Y was in front.
Reverse the labels in my comments if X is in front.  In any frame of either ship after it starts its acceleration, the ship in front moves first, breaking the string.

[David Cooper]

If they start with the clocks synchronised for a frame half way in between and start with a slack line with just the right amount of slack in it, it could become tight half way through and then go slack again.

A nit correction: Other way around.  It could be tight at first, and gets slack as the two ships approach the frame in which their clocks are synchronized, and then get tight again at the end.

You're right. I realised that as soon as I'd switched off my computer and considered booting it up again to correct it, but decided just to leave it there as an intelligence test. Usually I can correct things like that the next day before anyone picks up on it, but you're too quick witted.

[David Cooper]

Yep, i dont understand SR & GR. Re LET i agree that the thread might snap, & that the distance tween center of mass of X & Y doesnt change etc, all of that is common sense. But in SR & GR space along any one line must contract etc evenly & equally along every point along that line, to infinity. Hencely if X contracts then so does Y & so does the string & so does space, hencely the string doesnt snap.

It is odd, because even in SR it should be recognised that the leading ship has accelerated at exactly the same rate as the trailing one. The acceleration of the leading ship appears to be stronger because of the changing synchronisation issues - if they keep resynchronising clocks while they accelerate, they'll both calculate that the leading ship is accelerating more strongly than the other regardless of what their gauges are telling them about the actual power put down. If they both adjust the power to try to maintain the right output for the amount of "corrected" time that's passed, the leading ship will accelerate less and the trailing one will accelerate more, and the result of this will be length-contraction of the distance between their centres of mass to match the length-contraction of each ship. They should notice at the end of this process that the trailing ship has used up more fuel though. This is a weird issue, so it's easy to see why a lot of people in the SR camp might produce incorrect answers for it, but the ones who apply SR correctly will get the same answers as we do by using LET. While it initially looks as if this illustrates another broken aspect of SR, it's actually quite easy to explain away - when they are up to speed and the leading rocket appears to be further ahead despite using the same amount of fuel, retrospectively it will simply look as if it began its acceleration first and stopped accelerating first too - the original idea that the beginning of the acceleration looked simultaneous for both ships at the time will now be regarded as an illusion.

Einstein's gamma is merely a math-trick to ensure that the speed of light is isotropic in all frames. But the resulting changes in length ticking etc are not real. Hencely not being real this allows the lengths tickings etc to be different for different observers. If they can be different in that way then clearly they are not real changes. Which begs the question what use is SR & GR. The answer is that they give good numbers for some realworld happenings. But u shoodnt then peer into any & every little baby interim term etc & say that that baby is itself real & any associated baby number good just because the big adult end term is a goodish number.

SR and GR are indeed just a mathematical abstraction - they turn time into a space dimension (in which every fundamental component of anything is of infinite length) and they lose actual time from the model altogether, so they're left with a static block universe in which nothing ever happens and in which the future was never generated from the past in order of causation, rendering all the apparent causation fake. It's all a fraud. The original version of SR wasn't 4D, but it generated contradictions, so Minkowski tried to fix it by creating the mathematical abstraction, and in the 4D versions, light doesn't even have a speed because it reduces all the paths that it follows to zero length. Whenever Einsteinists talk about the speed of light being c, they're mixing incompatible models.

The worst consequences of GR are found when they look at black holes. Look at the nonsense that comes out of there when they talk about wormholes and about things in black holes disappearing from the universe due to weird things happening to the space and "time" dimensions. In reality, nothing weird happens there at all - apparent time simply slows because the local speed of light slows to zero (relative to the black hole) and all functionality stops, but time itself ticks on completely unslowed while the content of space there freezes up - it's merely impossible for any clock to tick along with it. The laws of LET don't break in black holes - they tell us exactly what's going on inside them, and it's all rational. Nothing can cross the event horizon inwards, never mind out, because it can't go faster than light, so all the material that falls "into" a black hole actually gets stuck just outside the event horizon until the energy density there becomes sufficiently high to generate a new event horizon to the other side of it. There's also no singularity on the inside - its just a globe of space in which light can't move and everything else is frozen in place too, scattered all throughout that globe. Some warping of that globe is possible though, and this becomes considerable when two black holes merge. I speculated recently that the two black holes might not merge fully, maintaining a separation where their event horizons meet, but I realise now that the energy density will be so high that the gap in between will have the speed of light in it reduced to zero too, so it just becomes like any other part of the interior of the black hole. Many physicists have wasted their entire careers studying fantasy physics by applying GR to black holes, pumping out all sorts of nonsense that misleads the public in the process. GR and SR have both been disproved, but they're incapable of accepting that reality.

[Halc]

It is odd, because even in SR it should be recognised that the leading ship has accelerated at exactly the same rate as the trailing one.

They have.  If some observer is in one of the ships, he’d not be able to tell which one he was on by noting a less-than scheduled acceleration, or by how long the thrust lasted. This is as stipulated in the OP.  The two ships could be a line of 100 ships, each one (except the end ones) being both the leading and the trailing ship of the one on either side respectively.

The acceleration of the leading ship appears to be stronger because of the changing synchronisation issues - if they keep resynchronising clocks while they accelerate, they'll both calculate that the leading ship is accelerating more strongly than the other regardless of what their gauges are telling them about the actual power put down.

They’d calculate that the lead ship is effectively further from the equivalent gravity well so the time in the lead ship is dilated less.  Time moves faster for the lead ship than the trailing one, so it gets its thrusting done sooner in the accelerating frame of one ship or the other.  Except at the beginning and the end (when the rear ship finishes), they are never both stationary in any frame, so there is no frame where they can obviously re-sync their clocks as they move.

If they both adjust the power to try to maintain the right output for the amount of "corrected" time that's passed, the leading ship will accelerate less and the trailing one will accelerate more, and the result of this will be length-contraction of the distance between their centres of mass to match the length-contraction of each ship. They should notice at the end of this process that the trailing ship has used up more fuel though.

Same fuel consumption since they’ll both be going the same speed at the end, just like they do with no speed correction to keep the proper distance between the ships constant like that.

Minkowski tried to fix it by creating the mathematical abstraction, and in the 4D versions, light doesn't even have a speed because it reduces all the paths that it follows to zero length.

aaand out comes the stuff you can’t push on the main forum….

[David Cooper]

Minkowski tried to fix it by creating the mathematical abstraction, and in the 4D versions, light doesn't even have a speed because it reduces all the paths that it follows to zero length.

aaand out comes the stuff you can’t push on the main forum….

What makes you think such points can't be made on the main forum? It is a correct description of SR and GR which is beyond dispute. The issue of light reducing all paths to zero length came up here in the physics section several years ago, and when I proved the point, the moderator who was on the other side of the argument suddenly disappeared and was never heard of here again, despite being asked by a neutral participant to respond to what I had demonstrated. (He didn't just happen to pop off at that moment - I recently found that he's still very much alive and active on a maths forum.)

A correct understanding of Spacetime shows that every point in the universe is zero distance away from every other point for light. The faster an object moves, the shorter the distance it needs to travel through space to get from A to B, and the shorter the length of the trip in the time dimension will be too. When you get to objects moving at 0.99999999999c, they're already making the trip close to zero length and zero time, and there's no possibility of light travelling from A to B covering a longer distance or taking a longer time than such high speed objects to make that trip. It is futile to pretend that this is not a feature of the 4D models. You are logically forced to accept that that is how they are structured.

[Halc]

A correct understanding of Spacetime shows that every point in the universe is zero distance away from every other point for light.

It is what is approached (locally) as an object approaches light speed, yes.
But there is no 'for light'.  You make it sound like from the reference frame of light, and there is no such valid reference frame.  It was the reference to light not having a speed that was wrong.  Light moves locally at fixed speed in all frames, and there is thus no frame in which a photon is locally stationary.

[mad aetherist (OP)]

Yep, i dont understand SR & GR. Re LET i agree that the thread might snap, & that the distance tween center of mass of X & Y doesnt change etc, all of that is common sense. But in SR & GR space along any one line must contract etc evenly & equally along every point along that line, to infinity. Hencely if X contracts then so does Y & so does the string & so does space, hencely the string doesnt snap.

It is odd, because even in SR it should be recognised that the leading ship has accelerated at exactly the same rate as the trailing one. The acceleration of the leading ship appears to be stronger because of the changing synchronisation issues - if they keep resynchronising clocks while they accelerate, they'll both calculate that the leading ship is accelerating more strongly than the other regardless of what their gauges are telling them about the actual power put down. If they both adjust the power to try to maintain the right output for the amount of "corrected" time that's passed, the leading ship will accelerate less and the trailing one will accelerate more, and the result of this will be length-contraction of the distance between their centres of mass to match the length-contraction of each ship. They should notice at the end of this process that the trailing ship has used up more fuel though. This is a weird issue, so it's easy to see why a lot of people in the SR camp might produce incorrect answers for it, but the ones who apply SR correctly will get the same answers as we do by using LET. While it initially looks as if this illustrates another broken aspect of SR, it's actually quite easy to explain away - when they are up to speed and the leading rocket appears to be further ahead despite using the same amount of fuel, retrospectively it will simply look as if it began its acceleration first and stopped accelerating first too - the original idea that the beginning of the acceleration looked simultaneous for both ships at the time will now be regarded as an illusion.

Einstein's gamma is merely a math-trick to ensure that the speed of light is isotropic in all frames. But the resulting changes in length ticking etc are not real. Hencely not being real this allows the lengths tickings etc to be different for different observers. If they can be different in that way then clearly they are not real changes. Which begs the question what use is SR & GR. The answer is that they give good numbers for some realworld happenings. But u shoodnt then peer into any & every little baby interim term etc & say that that baby is itself real & any associated baby number good just because the big adult end term is a goodish number.

SR and GR are indeed just a mathematical abstraction - they turn time into a space dimension (in which every fundamental component of anything is of infinite length) and they lose actual time from the model altogether, so they're left with a static block universe in which nothing ever happens and in which the future was never generated from the past in order of causation, rendering all the apparent causation fake. It's all a fraud. The original version of SR wasn't 4D, but it generated contradictions, so Minkowski tried to fix it by creating the mathematical abstraction, and in the 4D versions, light doesn't even have a speed because it reduces all the paths that it follows to zero length. Whenever Einsteinists talk about the speed of light being c, they're mixing incompatible models.

The worst consequences of GR are found when they look at black holes. Look at the nonsense that comes out of there when they talk about wormholes and about things in black holes disappearing from the universe due to weird things happening to the space and "time" dimensions. In reality, nothing weird happens there at all - apparent time simply slows because the local speed of light slows to zero (relative to the black hole) and all functionality stops, but time itself ticks on completely unslowed while the content of space there freezes up - it's merely impossible for any clock to tick along with it. The laws of LET don't break in black holes - they tell us exactly what's going on inside them, and it's all rational. Nothing can cross the event horizon inwards, never mind out, because it can't go faster than light, so all the material that falls "into" a black hole actually gets stuck just outside the event horizon until the energy density there becomes sufficiently high to generate a new event horizon to the other side of it. There's also no singularity on the inside - its just a globe of space in which light can't move and everything else is frozen in place too, scattered all throughout that globe. Some warping of that globe is possible though, and this becomes considerable when two black holes merge. I speculated recently that the two black holes might not merge fully, maintaining a separation where their event horizons meet, but I realise now that the energy density will be so high that the gap in between will have the speed of light in it reduced to zero too, so it just becomes like any other part of the interior of the black hole. Many physicists have wasted their entire careers studying fantasy physics by applying GR to black holes, pumping out all sorts of nonsense that misleads the public in the process. GR and SR have both been disproved, but they're incapable of accepting that reality.

I see that in the upwards accelerating elevator analogy Einsteinians say  that a clock near the ceiling will tick faster than a clock near the floor, thusly giving perfect equivalence (to an elevator stationed in a g field). The X-string-Y spaceship analogy is probly partly a horizontal rehash of the vertical elevator thort-X (talking bout the Einsteinian universe here). So, initially X & Y are stationary, then X starts acceleration (to the left in my world) at the same true time as Y, & during acceleration Einsteinians deem that X's clock ticks faster than Y's clock, & X (unknowingly) accelerates more than Y (because X uses fuel at a greater rate), & eventually the string must snap, & when it snaps then X & Y will both see it snap (albeit Y first, X later). I think that that is one (Einsteinian) answer. But i have some queries.

(1) X uses fuel at a greater rate than Y. But initially X uses fuel at the same  rate as Y. Then initially they must both accelerate equally (both accelerations are say 1.0). But somehow X's clock immediately starts to tick faster than Y's, even tho they are momentarily accelerating at the same rate. Somewhere in that first second X's clock's ticking jumps from 1.0 to 1.1, & X's fuel flow jumps from 1.0 to 1.1, & X's accel jumps from 1.0 to 1.1 (X & Y start with fuelflow-needles & acceleration-needles sitting on 1.0)(& all needles of course remain on 1.0 throughout).  Where exactly in that first second do these three jumps happen? (This refers to X, Y doesnt suffer any jumps)(X of course doesnt see or feel the jumps)(but X & Y will both see that something is wrong, ie they will see that the other ship is drifting)(& both will know that something is wrong when the string eventually snaps). So, where exactly in that first second do these three jumps happen?

(2) X & Y are stationary at 0.0000 sec, & both ships have the same length at 0.0000 sec. Both start accelerating, & initially both start to shorten, equally.  If the jumps happen at 0.0001 sec, then at that time spaceship X must start to shorten at a greater rate than Y.  Which happens first, shortening of X, or faster ticking in X. (2a) Do clocks tick faster because of shortening, or (2b) does shortening happen because the clocks tick faster. (2c) Or can both faster ticking & shortening happen together, at the same time. (3) Thems three questions apply to both X & to Y, but similar questions can be asked re the jump in ticking & shortening in X, u can call these three questions (3a) & (3b) & (3c).

(4) A slight variation. Spaceship X is identical to Y, but Y has moved its clock & thrusters to its nose (Y's thrusters still point backwards)(to my right)(whilst X's clock & thrusters are at the tail as built)(& point to my right)(ie point to Y).
Initially X & Y are stationary (as in (1)), then immediately both accelerate (as in (1)), etc (going to my left)(as in (1)).  Momentarily, both clocks tick at the same rate (as in (1)) etc. But, unlike in (1), will not Y be the ship that accelerates faster etc (4a) (in which case the string will slacken), & (4b) will Y need to fill out an accident report, ie will it eventually collide with X.

[mad aetherist (OP)]

Minkowski tried to fix it by creating the mathematical abstraction, and in the 4D versions, light doesn't even have a speed because it reduces all the paths that it follows to zero length.

aaand out comes the stuff you can’t push on the main forum….

What makes you think such points can't be made on the main forum? It is a correct description of SR and GR which is beyond dispute. The issue of light reducing all paths to zero length came up here in the physics section several years ago, and when I proved the point, the moderator who was on the other side of the argument suddenly disappeared and was never heard of here again, despite being asked by a neutral participant to respond to what I had demonstrated. (He didn't just happen to pop off at that moment - I recently found that he's still very much alive and active on a maths forum.)

A correct understanding of Spacetime shows that every point in the universe is zero distance away from every other point for light. The faster an object moves, the shorter the distance it needs to travel through space to get from A to B, and the shorter the length of the trip in the time dimension will be too. When you get to objects moving at 0.99999999999c, they're already making the trip close to zero length and zero time, and there's no possibility of light travelling from A to B covering a longer distance or taking a longer time than such high speed objects to make that trip. It is futile to pretend that this is not a feature of the 4D models. You are logically forced to accept that that is how they are structured.

So, at high speeds trips can take almost zero time, in which case if c=c then it can be said that the trip distance is also almost zero. Interesting.

[Halc]

So, at high speeds trips can take almost zero time, in which case if c=c then it can be said that the trip distance is also almost zero.

In the frame where the speed is high, the trip takes a long time.  A trip cannot be taken at c, but it can get arbitrarily close.  The distance traveled is still a long way and takes a long time.

In the frame of the thing 'making the trip', it has negligible speed, so it just sits still for a short time.

[Halc]

I see that in the upwards accelerating elevator analogy Einsteinians say  that a clock near the ceiling will tick faster than a clock near the floor, thusly giving perfect equivalence (to an elevator stationed in a g field).

They would not word it that way, but essentially, yes.

The X-string-Y spaceship analogy is probly partly a horizontal rehash of the vertical elevator thort-X (talking bout the Einsteinian universe here). So, initially X & Y are stationary, then X starts acceleration (to the left in my world) at the same true time as Y, & during acceleration Einsteinians deem that X's clock ticks faster than Y's clock

No.  Both ships are doing the same thing, so both clocks tick at the same rate in the frame in which they were inititally stationary.  If you’re talking about a different frame, it needs to be specified.  Absent that, I assume we’re using the original frame.

& X (unknowingly) accelerates more than Y (because X uses fuel at a greater rate),

Nope.  Identical.

& eventually the string must snap, & when it snaps then X & Y will both see it snap (albeit Y first, X later).

If it can’t stretch at all, it snaps right away.  If it lasts a while and breaks in the middle, who sees it first seems frame dependent, but yes, I think Y sees it first in O’s frame because Y is moving towards the break, meeting the light from it, while X is moving away and the light needs to go further to catch up.

(1) X uses fuel at a greater rate than Y.

Same rate the whole time.

But somehow X's clock immediately starts to tick faster than Y's

No

So, where exactly in that first second do these three jumps happen?

There are never any ‘jumps’ no matter the frame you choose.  There are no discontinuities in this example.

If the jumps happen at 0.0001 sec, then at that time spaceship X must start to shorten at a greater rate than Y.

There are no jumps.  Both ship lengths dilate down equally.

(4) A slight variation. Spaceship X is identical to Y, but Y has moved its clock & thrusters to its nose (Y's thrusters still point backwards)(to my right)(whilst X's clock & thrusters are at the tail as built)(& point to my right)(ie point to Y).

There would be no difference in this scenario.  Ships still accelerate identically and the string breaks.  Where the engine is has no significant imact.

[David Cooper]

But there is no 'for light'.  You make it sound like from the reference frame of light, and there is no such valid reference frame.

The word "for" does not mean light is at rest in any frame of reference. There has to be some reality for light though, and we have more and more extreme frames reducing the distance that fast moving matter has to travel through the space dimensions and time dimension with these tending to zero. For light, the distance through space and time dimensions is always going to be zero because it can't be anything greater without making it possible for it to be overtaken by matter.

It was the reference to light not having a speed that was wrong.  Light moves locally at fixed speed in all frames, and there is thus no frame in which a photon is locally stationary.

If it's covering all its trips in zero distance, it makes no sense to say it has a speed. It merely has an apparent speed in 4D models. When you say there is no frame in which it's stationary, that's only because the range of frames is infinite, never quite reaching light's equivalent of a frame, but light itself still has a kind of frame which merely isn't a member of the set of frames of reference. In reality though, the 4D models are merely a mathematical abstraction, so we're arguing about how many angels can dance on the head of a pin. For a real description of nature, you need to use LET instead.

[David Cooper]

I see that in the upwards accelerating elevator analogy Einsteinians say  that a clock near the ceiling will tick faster than a clock near the floor, thusly giving perfect equivalence (to an elevator stationed in a g field).

The phenomenon of relativity (I'm not talking about a theory of relativity here, but about nature itself) provides a lot of coincidences, and one of those coincidences is that the maths of acceleration matches up to the maths of gravitational pull, but they are not the same thing - it's a fun game using GR to interpret the scenario in question, but it is nothing more than a game, and it certainly doesn't provide any real understanding of what's going on.

(1) X uses fuel at a greater rate than Y. But initially X uses fuel at the same  rate as Y. Then initially they must both accelerate equally (both accelerations are say 1.0). But somehow X's clock immediately starts to tick faster than Y's, even tho they are momentarily accelerating at the same rate. Somewhere in that first second X's clock's ticking jumps from 1.0 to 1.1, & X's fuel flow jumps...

What actually happens is that the change in synchronisation leads to them continually rewriting the history of the start times for the acceleration for the two ships because they always try to account for it using the frame in which they are currently at rest, and this repeatedly pushes forward the claimed start time for the leading ship's acceleration. An earlier start leads to the apparent gap between the two ships continually opening wider.

Where exactly in that first second do these three jumps happen?

They're continual - an infinite series of tiny jumps, but they aren't really jumps because they're actually just recalculations about the history of events, rewriting the time gap between the two ships starting their accelerations. If you don't rewrite history in that way and just stick to a single frame, there is no difference between the two accelerations and no rewriting of the start times.

(2a) Do clocks tick faster because of shortening, or (2b) does shortening happen because the clocks tick faster. (2c) Or can both faster ticking & shortening happen together, at the same time.

If you're continually changing the frame you're using to analyse events (as a person on either ship automatically does when looking with their own eyes at the events unfolding for them), then no change in ticking rate or ship lengths is seen at all. These changes are only measured if you stick to one frame for all your measurements. Choose one frame and you'll measure that the clocks are running slower and slower while the ships contract in length, but choose another frame and you can measure the clocks ticking faster instead while the ships lengthen.

(4) A slight variation. Spaceship X is identical to Y, but Y has moved its clock & thrusters to its nose (Y's thrusters still point backwards)(to my right)(whilst X's clock & thrusters are at the tail as built)(& point to my right)(ie point to Y).

Even if you stick the rockets on Y on the end of a long rod that puts them ahead of X and if you also have a long rod putting X's rockets behind Y, the behaviour of the two ships won't change at all, just so long as the person pushing the start button is in the same place as before. The signal will take time to get to the rockets, and that delay will cancel out the positioning differences with the rockets. It's all about synchronisation.

[mad aetherist (OP)]

I see that in the upwards accelerating elevator analogy Einsteinians say  that a clock near the ceiling will tick faster than a clock near the floor, thusly giving perfect equivalence (to an elevator stationed in a g field).

The phenomenon of relativity (I'm not talking about a theory of relativity here, but about nature itself) provides a lot of coincidences, and one of those coincidences is that the maths of acceleration matches up to the maths of gravitational pull, but they are not the same thing - it's a fun game using GR to interpret the scenario in question, but it is nothing more than a game, and it certainly doesn't provide any real understanding of what's going on.

(1) X uses fuel at a greater rate than Y. But initially X uses fuel at the same  rate as Y. Then initially they must both accelerate equally (both accelerations are say 1.0). But somehow X's clock immediately starts to tick faster than Y's, even tho they are momentarily accelerating at the same rate. Somewhere in that first second X's clock's ticking jumps from 1.0 to 1.1, & X's fuel flow jumps...

What actually happens is that the change in synchronisation leads to them continually rewriting the history of the start times for the acceleration for the two ships because they always try to account for it using the frame in which they are currently at rest, and this repeatedly pushes forward the claimed start time for the leading ship's acceleration. An earlier start leads to the apparent gap between the two ships continually opening wider.

Where exactly in that first second do these three jumps happen?

They're continual - an infinite series of tiny jumps, but they aren't really jumps because they're actually just recalculations about the history of events, rewriting the time gap between the two ships starting their accelerations. If you don't rewrite history in that way and just stick to a single frame, there is no difference between the two accelerations and no rewriting of the start times.

(2a) Do clocks tick faster because of shortening, or (2b) does shortening happen because the clocks tick faster. (2c) Or can both faster ticking & shortening happen together, at the same time.

If you're continually changing the frame you're using to analyse events (as a person on either ship automatically does when looking with their own eyes at the events unfolding for them), then no change in ticking rate or ship lengths is seen at all. These changes are only measured if you stick to one frame for all your measurements. Choose one frame and you'll measure that the clocks are running slower and slower while the ships contract in length, but choose another frame and you can measure the clocks ticking faster instead while the ships lengthen.

(4) A slight variation. Spaceship X is identical to Y, but Y has moved its clock & thrusters to its nose (Y's thrusters still point backwards)(to my right)(whilst X's clock & thrusters are at the tail as built)(& point to my right)(ie point to Y).

Even if you stick the rockets on Y on the end of a long rod that puts them ahead of X and if you also have a long rod putting X's rockets behind Y, the behaviour of the two ships won't change at all, just so long as the person pushing the start button is in the same place as before. The signal will take time to get to the rockets, and that delay will cancel out the positioning differences with the rockets. It's all about synchronisation.

Yes i like that rocket on long rod stuff. But note that i said that the clocks & thrusters are both together on X & Y, & i also meant but didnt actually say the start button (& Captain) etc. So, if all of the essentials were on the ends of your long rods on X & Y such that X's were then behind Y's then i guess that the string would be affected in the opposite way (eg slacking instead of snapping).

[mad aetherist (OP)]

I see that in the upwards accelerating elevator analogy Einsteinians say  that a clock near the ceiling will tick faster than a clock near the floor, thusly giving perfect equivalence (to an elevator stationed in a g field).

They would not word it that way, but essentially, yes.

The X-string-Y spaceship analogy is probly partly a horizontal rehash of the vertical elevator thort-X (talking bout the Einsteinian universe here). So, initially X & Y are stationary, then X starts acceleration (to the left in my world) at the same true time as Y, & during acceleration Einsteinians deem that X's clock ticks faster than Y's clock

No.  Both ships are doing the same thing, so both clocks tick at the same rate in the frame in which they were inititally stationary.  If you’re talking about a different frame, it needs to be specified.  Absent that, I assume we’re using the original frame.

& X (unknowingly) accelerates more than Y (because X uses fuel at a greater rate),

Nope.  Identical.

& eventually the string must snap, & when it snaps then X & Y will both see it snap (albeit Y first, X later).

If it can’t stretch at all, it snaps right away.  If it lasts a while and breaks in the middle, who sees it first seems frame dependent, but yes, I think Y sees it first in O’s frame because Y is moving towards the break, meeting the light from it, while X is moving away and the light needs to go further to catch up.

(1) X uses fuel at a greater rate than Y.

Same rate the whole time.

But somehow X's clock immediately starts to tick faster than Y's

No

So, where exactly in that first second do these three jumps happen?

There are never any ‘jumps’ no matter the frame you choose.  There are no discontinuities in this example.

If the jumps happen at 0.0001 sec, then at that time spaceship X must start to shorten at a greater rate than Y.

There are no jumps.  Both ship lengths dilate down equally.

(4) A slight variation. Spaceship X is identical to Y, but Y has moved its clock & thrusters to its nose (Y's thrusters still point backwards)(to my right)(whilst X's clock & thrusters are at the tail as built)(& point to my right)(ie point to Y).

There would be no difference in this scenario.  Ships still accelerate identically and the string breaks.  Where the engine is has no significant impact.

Hmmmmm -- I must admit that i dont understand. But ok what about this -- X & Y are going along at speed to the left together with a new tight thread tween -- & then X & Y decelerate at the same time & rate etc -- what happens now?

[Halc]

I must admit that i dont understand. But ok what about this -- X & Y are going along at speed to the left together with a new tight thread tween -- & then X & Y decelerate at the same time & rate etc -- what happens now?

'At the same time' in which frame?  The answer very much depends on this.

Assuming you mean simultaneously in your observer O's frame in which X and Y are going along at speed, then the string will go slack.