[David Cooper (OP)]

I've been told by someone not to send a paper to a science journal because it's old news, so can someone point me to a published paper (or papers) in a respected peer-reviewed science journal that cover(s) the same ground as this? If so, I want to be able to point to it rather than pointing to my own work and having them dismiss it on the basis that it isn't in a peer reviewed science journal:-

Method to measure absolute velocities through an expanding space fabric, and as a bi-product, to measure the local rate of expansion of space.

David A. Cooper


Abstract

In a universe where galaxies continually move further apart due to the expansion of the space between them, we can show in principle that an experiment can be designed to measure definitive non-zero absolute velocities for objects in space, while it guarantees the avoidance of a null result in any location where there is actual expansion. The local rate of expansion of space can be derived from this measurement with equal precision. Of particular significance, this experiment provides a means to test Lorentz Ether Theory against Einstein's Special Theory of Relativity if carried out in a place where we are certain that expansion is taking place: uniquely in this overlooked situation, the two theories make different predictions about the outcome, so it must be possible to disprove one of them experimentally if expansion of space is real.


Introduction

The expansion of the universe should enable the separation distance between two clocks to increase without changing their velocity through the space fabric, even in a case where they are initially comoving but end up moving relative to each other due to that expansion. In this very special circumstance, the prediction of Lorentz Ether Theory differs from that of STR. LET predicts that the clocks will move apart while continuing to tick in sync with each other and they can thereby reveal their absolute speeds of motion, while STR cannot allow the existence of any such asymmetry. For the purposes of this paper, we assume that the space itself is expanding, thereby carrying galaxies to increasing separation distances. (The alternative explanation of galaxies being sent out into an existing void by the big bang would destroy our current explanation for the cosmic microwave background because that radiation would have been lost outwards into the void long ago instead of continuing to pass us today.) On this basis, we can demonstrate that the existence of absolute speeds of motion cannot be avoided in an expanding universe, and that they can not only be measured in principle, but that measuring them (along with the local rate of expansion) may not be many decades beyond the reach of current technology.

Method

We place two clocks a small number of astronomical units apart in reasonably deep space (outside the solar system), both at rest in reference frame A. We measure their separation distance with respect to frame A, and we synchronise the clocks by that frame once they are in position. To aid this, we place a marker object half way between the two clocks, again at rest in frame A, and frame A will remain tied to this marker throughout. We wait to allow the expansion of space to increase the separation between the three objects by a decent amount, then at a pre-arranged time both clocks send out a signal at the speed of light back to the central marker so that we can measure any difference in their times of arrival there. If the marker is genuinely at rest in space (or if there is no such thing as absolute velocity, or if there is no local expansion) the clocks will still display exactly the same time as each other, as measured in frame A, and the signals will reach the central marker simultaneously. However, if the central marker is actually moving through space in any direction not perpendicular to a straight line connecting the two clocks, one of signals will have to travel a greater distance through space to catch up with the moving central marker than the other, and while at the start of the experiment such signals would still have reached the marker simultaneously due to the skewed synchronisation of the clocks (caused by them being synchronised on the erroneous basis that they were stationary), that will no longer be the case by the end of the experiment due to the extra separation distance introduced by the expansion of space: both signals will have to cross the exact same extra amount of separation distance, but one will necessarily take longer to do so. That timing difference will not be cancelled out in the normal way of relativity.

Clearly there could initially be a null result even if absolute speeds are real (because the system might by chance have an absolute speed of motion through space of zero), but we can repeat the experiment using frame B where this new frame moves relative to frame A in the same direction as the straight line connecting the two clocks in the first running of the experiment. We would now have the marker and clocks begin the second running of the experiment by sitting at rest in frame B. If there was no such thing as absolute velocity, then a null result would be forced for both the first and second runnings of this experiment, and STR predicts this double null result. However, for that to occur, there could be no expansion of the local space in which the experiment is operating.


Discussion

That last claim needs to be expanded upon to demonstrate its validity. If we have a double null result and we also have expansion of the local space in which the experiment is operating, to maintain that null result for both the frame A and B runnings, we would need to have two of the four signals (light pulses or radio waves) travel in the same direction at different speeds, and only a tiny part of that difference can be accounted for by further expansion of the space between them during this short end phase of the experiments. We can arrange for the frame A apparatus (clocks A1, A2 and central marker AM) and frame B apparatus (B1 B2 and BM) to end up in the same vicinity by the end of the first phase of the experiment such that the signals from clocks A1 and B1 can travel together side by side during this second phase of the experiment, so they must match each other for pace precisely. The signals from clocks A2 and B2 could still be a considerable distance apart due to length contraction on the frame B set of objects, but it's easy to see that any difference in their speed caused by the space expanding between them would be dwarfed by the required speed difference to get a double null result. Consider an example where the frame B apparatus is moving at 0.5c relative to the stationary frame A apparatus: there is no possibility of cancelling out the difference caused by the light having to cover the extra distance inserted by the expansion of space (during the first phase) at 0.5c relative to it in one direction and at 1.5c relative to it the opposite way. If we get a double null result, there is categorically no expansion.

Note that due to length contraction, the amount of expansion applying to the frame B apparatus will be reduced relative to the original distance between the clocks over a given length of time, but the duration of that running of the experiment will be increased to match, resulting in the exact same amount of expansion occurring before the signals are sent back to the central marker. This actually provides us with a second measurable asymmetry by causing the signals to arrive back extra late in the frame B case: the added distance caused by expansion of space in the frame B case is not length contracted.

An important question is whether there should actually be any expansion of space locally. If in the worst case scenario the universe expands only at relatively narrow plate boundaries far from galaxies, it could take us millions of years to get our apparatus into position to make any measurements there, but it is likely that the expansion is more evenly spread, and that a reasonable amount is taking place here too, but we now have a way to test that to find out. A double null result would be highly informative because that would rule out local expansion (or show it to be reduced beyond the resolution of the measuring apparatus, so it would be wise to wait until we have built apparatus with one or two orders of magnitude greater precision than we expect to need before we start putting it in rockets). For the rest of this paper though, the reader should simply assume that the experiment is being carried out in a location where there is expansion.

There are a couple of gravitational complications to consider. Even if we carried out the experiment in the middle of the biggest void between galaxies, we would still have distant sources of mass pulling the clocks further apart, so we need to compensate for that effect. An inconvenient way to do this would be to repeat the experiment a long time later when the galaxies are much further apart with their influence diminished, while the increasing rate of expansion of the universe would also lead to increased reliability of the results by amplifying the effect we are trying to measure. After repeating this a few times over the course of millions or billions of years, it would be possible to make a highly accurate adjustment to the results to compensate entirely for the effects of gravitational pull. A similar complication is that in a case where there is more mass attracting the system in one direction than the opposite way, then the central marker could be accelerating in the direction of one of the two clocks, which means it cannot be relied upon to remain at rest in frame A. However, again we could repeat the experiment a long time later when those attractions are both weaker, and then adjustments can be made to cancel out the effect. Such long delays in getting definitive results would be frustrating, but fortunately it would also be possible to calculate the amount of distant mass and its distribution just by looking at it and assessing its extent, then accelerations could be applied to all the clocks and markers to cancel out the accelerations caused by the predicted gravitational attractions. As we improve our measurements and judgements of the amount and distribution of mass in the visible universe, we will be able to carry out this experiment with increasing accuracy over time. Even if this is not done with good information though, we would still get useful measurements of average absolute speeds from accelerating sets of apparatus, just as you can measure that a car accelerating from 40 to 50 mph is moving more slowly than a car accelerating from 45 to 55 mph, so it is not essential to get these judgements completely right.

... (second half follows below)

[David Cooper (OP)]

Building the experiment to carry it out locally may not be many decades beyond our current technology. The universe expands at a little over 70 mm per second per parsec, which is not far short of a metre per month over a distance of one astronomical unit (the distance between the Earth and the sun), and if it expands here locally to a reasonable fraction of that, we could get useful results from it. We would likely want to aim for between ten and a hundred times that length of separation though as it would make little difference to the time taken to put all the clocks in position if they are to be placed somewhere far out beyond the influence of Neptune and the other gas giants. By placing boxes around the clocks and markers, we can shade them from any radiation and particles that might accelerate them, and those boxes would then use tiny thrusters to keep each of them positioned with a shielded object at the centre, so we can prevent the clocks and markers from being blown about by any kind of particle wind. Setting the objects' initial relative speed to zero would be hard to do with great precision, so tiny errors could build up over time, but we actually know where the clocks should be at any point in time relative to the central marker for a given predicted rate of expansion, which means we can make infinitesimal adjustments to their speed to keep them in exactly the right places throughout the course of the experiment by shooting occasional photons at them inside the boxes, so it is unnecessary to rely on the expansion of space to control this. Most of the adjustments would be made early on though with the errors gradually becoming smaller as we set the objects' speeds with greater precision, and indeed, most of that would be done before the start of the actual experiment. If we separate them at the same rate as the predicted expansion of space, then we should find it impossible to get null results from both the frame A and frame B runnings of the experiment if that predicted expansion matches up to reality. If we were to do this in the absence of any local expansion of space, then we would get a null result both times, so this approach of dictating the change in separation is no cheat. In the same way, we can correct for predicted gravitational influences by shooting occasional photons at the clocks and central markers to nudge them about, thereby allowing us to carry out the experiment at relatively close range to the solar system. We can also calculate the depth of each clock in the collective gravity wells where they sit and make any adjustments necessary for any difference that this makes to their relative ticking rates.

The actual local rate of expansion of space may not match up well with the rate at which we separate our clocks, but it turns out that this does not always affect the result of the experiment. If we underestimate the expansion rate, we are in effect moving our clocks through space towards the central marker a tiny amount while the space between them expands, so they are still being separated practically as much by the expansion, but they are wandering a little through space in the direction they'll be sending their signals in later while that movement slows the timers by exactly the right amount to make up for the shorter distance those signals will later travel. In such a situation there will be the same difference in their arrival times at the central marker as if the expansion rate was matched precisely. (Technically there will be an infinitesimal difference in the amount of space-expansion-driven separation that they are exposed to due to them potentially being a small number of metres less far apart by the end of the first phase of the experiment, but with a separation distance measured in astronomical units, that will not even register.) It is similar when overestimating the expansion rate and moving the clocks too far apart, but the results would be affected: the clocks would wander a little further through space away from the central marker and they'd have to send their signals back through that extra space, so that would lead to the delays returning to the central marker late by an unknown amount. As it turns out, we conveniently find that the experiment can be carried out most reliably simply by maintaining the initial separation distances throughout the entire experiment instead of trying to separate them at the rate of expansion of the space between them, so that serves as a considerable simplification. Because we can send signals to the central marker at multiple times during the experiment from the exact same separation, we can also get early results and then continually improve the precision with later signals as the accumulation of expansion builds up the time difference between the two clocks.

When we run the experiment, the central marker (which also has a clock) can predict the time that the two signals would return to it if there was no expansion of the local space. Both signals will arrive late if there is any expansion, and we want to measure the times of those two delays. The size of one delay relative to the other allows us to calculate the absolute speed of the apparatus and its direction of travel, so, to give an extreme example, if one delay is measured as 13.925 times the size of the other, the apparatus is moving through space an an absolute speed of 0.866c. Whenever we divide the larger delay by the smaller delay, the result of this is equal to (1+a)/(1-a) where "a" is the absolute speed. Once we know the absolute speed, we can work out how much expansion occurred, and a simple way to do that is to add the two delays together to get a round-trip time for light to cover the extra length, then adjust that by the time dilation factor for that absolute speed, but we do this twice to convert to a value that will be the same for both the frame A and frame B runnings of the experiment, and this would also be the same value for a running of the experiment where the apparatus has an absolute speed of zero. The reason for doing it twice is that the extra space added by expansion is not length contracted, so it needs double adjustment to cancel out the extra delay. The size of the result will be directly proportional to the amount of expansion.

Clearly we would need to repeat the whole experiment with three different alignments to measure our full absolute speed of motion in 3D space and to check whether the speed of expansion is uniform in all three directions, but two thirds of that work could be done by a single set of apparatus doing a lap round the sun where it follows an octagonal path to make measurements using eight frames (A, C, E, G, B, D, F, H). Incidentally, two additional objects would need to accompany each set of apparatus, and these would be placed out to the side and "overhead", far enough out to be able to ensure the main three objects remain in line and to count up any sideways movement that might mount up. They would continually ping signals to and fro while the objects try to maintain the same timings for each round trip. Keeping the main three objects the right distance apart would be done in the same way: this would lead to repeated resynchronisation of a second clock at each of the two clock objects, while their main clock is not updated by this but is allowed to lag behind.

If we set the relative speed between the frame A and frame B runnings of the experiment to an unambitious 0.0001c (which is approximately the speed the Earth travels at round the sun), and if we separate each pair of clocks by 100 au and allow the space between them to expand for a month, we have nearly 50 m of new space (from the expansion) for each signal to cross (assuming a local rate of expansion close to the universe's average), and if frame A provides a null result, in the frame B running we should have one signal reach the central marker while the other signal is still 1 cm short of it, so that provides an indication of the size of measurement we need to be able to distinguish. However, if the absolute speeds are much higher due to the galaxy's likely speed boosting them ten times, we could be looking at the second signal being 10 cm short for one frame's apparatus and 9cm short for the other, which would make it easier to register an effect. If the expansion is reduced substantially in galaxies though, the differences will be smaller, so me may need ten or a hundred times greater precision, or we may need to use a higher relative speed between the two frames. These figures give hope though that we may be able to build and run an experiment of this kind within the first half of this century.


Conclusion

Even without carrying out the experiment, just as a thought experiment we can demonstrate that Einstein's Special Theory of Relativity is incompatible with an expanding universe, and that applies even if there is no local expansion so long as there is expansion somewhere in the universe: we could make the measurements wherever the expansion is occurring and identify absolute speeds of motion there. So, either there are absolute speeds of motion which we can in principle measure, or we do not have an expanding universe (but merely content spreading out through an existing space, and a major problem in accounting for the existence of the cosmic microwave background).

[Kryptid]

Given this goes against either an expanding Universe or special relativity (both of which are widely-accepted benchmarks of modern physics), I'm counting this as "new theory" material and moving it to the proper forum accordingly.

[David Cooper (OP)]

Given this goes against either an expanding Universe or special relativity (both of which are widely-accepted benchmarks of modern physics), I'm counting this as "new theory" material and moving it to the proper forum accordingly.

In doing so, you're defending voodoo (STR) and pushing real physics into the "hide this" subforum. Why do you want to do that? What is it with STR  that makes everyone in physics turn religious? Here's the response I got from one of the experts here in a pm:-

"The universe is outside the domain of applicability of SR. It's not fantasy and it works perfectly in its domain of applicability."

What is its domain of applicability if it doesn't relate to our actual universe? It's fantasy physics: the realm of magic. It is absolutely shameful that the most fundamental of the sciences continually tries to hide the truth from the world while brainwashing everyone into believing in a broken model which has been multipally disproved mathematically and which can now be disproved by experiment too. No wonder so many people have no respect for science when it comes to important issues like global warming and vaccines. How are we supposed to convince them of those things when the people at the top of the king of sciences are worshiping broken models and hiding all discussion of their faults? Do none of you realise the harm you're doing by behaving like this?

[Kryptid]

In doing so, you're defending voodoo (STR) and pushing real physics into the "hide this" subforum.

It's not hidden. Anyone visiting this board can still see it.

I'm also just upholding the rules. Challenges to mainstream physics goes here.

[David Cooper (OP)]

In doing so, you're defending voodoo (STR) and pushing real physics into the "hide this" subforum.

It's not hidden. Anyone visiting this board can still see it.

I'm also just upholding the rules. Challenges to mainstream physics goes here.

You know full well that the new theories forum exists primarily to hide crackpots, to the point that nothing serious that's posted there gets looked at. You should also be fully aware that there's nothing new about the theories involved in this. This is about testing between two leading theories that date back a century and where an experiment could now destroy one of them.

[Kryptid]

Feel free to take this issue up with an administrator or other moderators if you want this thread moved back.

[Jolly2]

they'll be sending their signals in later while that movement slows the timers by exactly the right amount to make up for the shorter distance

In doing so, you're defending voodoo (STR) and pushing real physics into the "hide this" subforum.

It's not hidden. Anyone visiting this board can still see it.

I'm also just upholding the rules. Challenges to mainstream physics goes here.

You know full well that the new theories forum exists primarily to hide crackpots,

Incorrect, they put them in "it cant be true"

[Jolly2]

I've been told by someone not to send a paper to a science journal because it's old news, so can someone point me to a published paper (or papers) in a respected peer-reviewed science journal that cover(s) the same ground as this? If so, I want to be able to point to it rather than pointing to my own work and having them dismiss it on the basis that it isn't in a peer reviewed science journal:-

Method to measure absolute velocities through an expanding space fabric, and as a bi-product, to measure the local rate of expansion of space.

David A. Cooper


Abstract

In a universe where galaxies continually move further apart due to the expansion of the space between them,

Ok I just started and this isn't correct, some galaxies are moving away but others are pulling together. So it's both.

we can show in principle that an experiment can be designed to measure definitive non-zero absolute velocities for objects in space, while it guarantees the avoidance of a null result in any location where there is actual expansion. The local rate of expansion of space can be derived from this measurement with equal precision. Of particular significance, this experiment provides a means to test Lorentz Ether Theory against Einstein's Special Theory of Relativity if carried out in a place where we are certain that expansion is taking place: uniquely in this overlooked situation, the two theories make different predictions about the outcome, so it must be possible to disprove one of them experimentally if expansion of space is real.

Hasn't it already been proven by experiment?

Introduction

The expansion of the universe should enable the separation distance between two clocks to increase without changing their velocity through the space fabric,

Ok now you lost me, how exactly are you going to have clocks show separation between galaxies and expansion of space? Velocity? You want to fire a clock into space?

even in a case where they are initially comoving but end up moving relative to each other due to that expansion. In this very special circumstance, the prediction of Lorentz Ether Theory differs from that of STR. LET predicts that the clocks will move apart while continuing to tick in sync with each other and they can thereby reveal their absolute speeds of motion, while STR cannot allow the existence of any such asymmetry. For the purposes of this paper, we assume that the space itself is expanding, thereby carrying galaxies to increasing separation distances.

Again not all

(The alternative explanation of galaxies being sent out into an existing void by the big bang would destroy our current explanation for the cosmic microwave background because that radiation would have been lost outwards into the void long ago instead of continuing to pass us today.) On this basis, we can demonstrate that the existence of absolute speeds of motion cannot be avoided in an expanding universe,

its called light speed.

and that they can not only be measured in principle, but that measuring them (along with the local rate of expansion) may not be many decades beyond the reach of current technology.

Method

We place two clocks a small number of astronomical units apart in reasonably deep space

So you do want to launch a clock.

(outside the solar system), both at rest in reference frame A. We measure their separation distance with respect to frame A, and we synchronise the clocks by that frame once they are in position. To aid this, we place a marker object half way between the two clocks, again at rest in frame A, and frame A will remain tied to this marker throughout. We wait to allow the expansion of space to increase the separation between the three objects by a decent amount,

How is that? they are inside this solar system,  they are not between two galaxies,  the space between planets isn't effected in the same way.

then at a pre-arranged time both clocks send out a signal at the speed of light back to the central marker so that we can measure any difference in their times of arrival there. If the marker is genuinely at rest in space (or if there is no such thing as absolute velocity, or if there is no local expansion) the clocks will still display exactly the same time as each other, as measured in frame A, and the signals will reach the central marker simultaneously. However, if the central marker is actually moving through space in any direction not perpendicular to a straight line connecting the two clocks, one of signals will have to travel a greater distance through space to catch up with the moving central marker than the other, and while at the start of the experiment such signals would still have reached the marker simultaneously due to the skewed synchronisation of the clocks (caused by them being synchronised on the erroneous basis that they were stationary), that will no longer be the case by the end of the experiment due to the extra separation distance introduced by the expansion of space: both signals will have to cross the exact same extra amount of separation distance, but one will necessarily take longer to do so. That timing difference will not be cancelled out in the normal way of relativity.

Clearly there could initially be a null result even if absolute speeds are real (because the system might by chance have an absolute speed of motion through space of zero), but we can repeat the experiment using frame B where this new frame moves relative to frame A in the same direction as the straight line connecting the two clocks in the first running of the experiment. We would now have the marker and clocks begin the second running of the experiment by sitting at rest in frame B. If there was no such thing as absolute velocity, then a null result would be forced for both the first and second runnings of this experiment, and STR predicts this double null result. However, for that to occur, there could be no expansion of the local space in which the experiment is operating.

Why would there be expansion inside a galaxy? This experiment wont answer the question of expansion outside it.

I'll stop here. That's effectively everything you are suggesting.

[David Cooper (OP)]

Ok I just started and this isn't correct, some galaxies are moving away but others are pulling together. So it's both.

Galaxies within groups can be pulling in towards each other, leading to them accelerating through space rather than being moved together by a contraction of the space between them. When you look far into space at the most distant visible galaxies, they are all moving away from us and are accelerating away due to the expansion of space.There's a distance beyond which they become invisible because the relative speed between them and us is higher than the speed of light due to the amount of expansion of space between us and them, and yet they are not moving through space at a higher speed than c.

Hasn't it already been proven by experiment?

There is no existing experiment that has done so and I'm not aware of anyone else thinking up an experiment like mine, but that doesn't mean it isn't already out there. Most papers are behind a paywall and I can't access them, but I have spoken to dozens of experts who have access to them who keep making a point of saying that there's no way to test for a difference between STR and LET, which means that if this proposed experiment is not new, few people can have heard about it. I suspect it's new because it's highly unlikely that anyone would think of looking down this path if they start out as believers in STR: I found it because it's more obvious to someone coming at it from the LET camp, and there aren't many of us around. As it is, it's taken me a decade to spot it.

Ok now you lost me, how exactly are you going to have clocks show separation between galaxies and expansion of space? Velocity? You want to fire a clock into space?

Clearly it needs more than one clock, but it's all described in the section "Method", and expanded on in the part called "Discussion".

Again not all

It doesn't need to be all. It's all the ones beyond a certain distance. It all depends on whether the gravitational attraction between two galaxies is strong enough to pull them together faster than the space is expanding between them. When they're close to each other, gravity can win out (but might still fail to if there are other galaxies further out cancelling out that pull), and when they're far apart, gravity doesn't have a chance of outgunning the expansion.

(The alternative explanation of galaxies being sent out into an existing void by the big bang would destroy our current explanation for the cosmic microwave background because that radiation would have been lost outwards into the void long ago instead of continuing to pass us today.) On this basis, we can demonstrate that the existence of absolute speeds of motion cannot be avoided in an expanding universe,

its called light speed.

What is? Are you referring to something in the part in brackets or the parts after the brackets? (Bear in mind that the brackets are there to prevent the "On this basis" referring to the part in brackets: it links back to the sentence before the brackets.)

How is that? they are inside this solar system,  they are not between two galaxies,  the space between planets isn't effected in the same way.

The old idea that the expansion only took place at plate-like boundaries was abandoned a long time ago.The current consensus has it that the expansion is taking place right through our galaxy, but as I don't have access to all the papers behind the paywall to refer to them, I used a wording that allowed me to leave that to the knowledge of the people reading my paper as they know. Even if that changes and returns to the idea that there's no expansion in the galaxy such that we can't measure it locally, that doesn't override the necessity for the experiment to pin down absolute speeds of motion at places where there is actual expansion. Just as a thought experiment, this destroys STR.

Why would there be expansion inside a galaxy? This experiment wont answer the question of expansion outside it.

How is space going to know only to expand away from galaxies? Even in the middle of the biggest empty regions the space there is at considerable depth in collective gravity wells, so what's it going to use to decide whether to expand or not? Is there some cut off value beyond which it stops expanding? How is that going to work? How does an empty region of space stretching over tens of millions of lightyears going to know how to expand that space uniformly at the right rate for its size to lead to smooth expansion in all directions in order to avoid causing weird optical effects? This is why the consensus moved to supporting the idea that the expansion is relatively even everywhere, including right through galaxies, but that the strong gravitational attractions between things that are gravitationally bound hides it. That may or may not be what's actually happening, so there's no guarantee that doing the experiment inside a galaxy would do anything other than produce null results, but the odds are against that, and we can still see that if we could get to a place where expansion is certainly happening, we could not get double null results there: we could not fail to measure the asymmetries that occur in such locations (if the experiment is sufficiently sensitive to be able to measure them in theory).

[Jolly2]

Ok I just started and this isn't correct, some galaxies are moving away but others are pulling together. So it's both.

Galaxies within groups can be pulling in towards each other, leading to them accelerating through space rather than being moved together by a contraction of the space between them. When you look far into space at the most distant visible galaxies, they are all moving away from us and are accelerating away due to the expansion of space.There's a distance beyond which they become invisible because the relative speed between them and us is higher than the speed of light due to the amount of expansion of space between us and them, and yet they are not moving through space at a higher speed than c.

Hasn't it already been proven by experiment?

There is no existing experiment that has done so and I'm not aware of anyone else thinking up an experiment like mine, but that doesn't mean it isn't already out there. Most papers are behind a paywall and I can't access them, but I have spoken to dozens of experts who have access to them who keep making a point of saying that there's no way to test for a difference between STR and LET, which means that if this proposed experiment is not new, few people can have heard about it. I suspect it's new because it's highly unlikely that anyone would think of looking down this path if they start out as believers in STR: I found it because it's more obvious to someone coming at it from the LET camp, and there aren't many of us around. As it is, it's taken me a decade to spot it.

Ok now you lost me, how exactly are you going to have clocks show separation between galaxies and expansion of space? Velocity? You want to fire a clock into space?

Clearly it needs more than one clock, but it's all described in the section "Method", and expanded on in the part called "Discussion".

Again not all

It doesn't need to be all. It's all the ones beyond a certain distance. It all depends on whether the gravitational attraction between two galaxies is strong enough to pull them together faster than the space is expanding between them. When they're close to each other, gravity can win out (but might still fail to if there are other galaxies further out cancelling out that pull), and when they're far apart, gravity doesn't have a chance of outgunning the expansion.

(The alternative explanation of galaxies being sent out into an existing void by the big bang would destroy our current explanation for the cosmic microwave background because that radiation would have been lost outwards into the void long ago instead of continuing to pass us today.) On this basis, we can demonstrate that the existence of absolute speeds of motion cannot be avoided in an expanding universe,

its called light speed.

What is? Are you referring to something in the part in brackets or the parts after the brackets? (Bear in mind that the brackets are there to prevent the "On this basis" referring to the part in brackets: it links back to the sentence before the brackets.)

How is that? they are inside this solar system,  they are not between two galaxies,  the space between planets isn't effected in the same way.

The old idea that the expansion only took place at plate-like boundaries was abandoned a long time ago.The current consensus has it that the expansion is taking place right through our galaxy, but as I don't have access to all the papers behind the paywall to refer to them, I used a wording that allowed me to leave that to the knowledge of the people reading my paper as they know. Even if that changes and returns to the idea that there's no expansion in the galaxy such that we can't measure it locally, that doesn't override the necessity for the experiment to pin down absolute speeds of motion at places where there is actual expansion. Just as a thought experiment, this destroys STR.

Why would there be expansion inside a galaxy? This experiment wont answer the question of expansion outside it.

How is space going to know only to expand away from galaxies? Even in the middle of the biggest empty regions the space there is at considerable depth in collective gravity wells, so what's it going to use to decide whether to expand or not? Is there some cut off value beyond which it stops expanding? How is that going to work? How does an empty region of space stretching over tens of millions of lightyears going to know how to expand that space uniformly at the right rate for its size to lead to smooth expansion in all directions in order to avoid causing weird optical effects? This is why the consensus moved to supporting the idea that the expansion is relatively even everywhere, including right through galaxies, but that the strong gravitational attractions between things that are gravitationally bound hides it. That may or may not be what's actually happening, so there's no guarantee that doing the experiment inside a galaxy would do anything other than produce null results, but the odds are against that, and we can still see that if we could get to a place where expansion is certainly happening, we could not get double null results there: we could not fail to measure the asymmetries that occur in such locations (if the experiment is sufficiently sensitive to be able to measure them in theory).

Stick with the question what is space that it can expand at all? Or bend.

The suggestion that space is expanding evenly implies a space "stretch".

If gravity is impacting on expansion you wouldn't see uniform expansion across the whole universe in all directions it would be more in some directions less in others.

I suppose your experiment would atleast answer the question with regards to space stretching.  If that even happens.

Still leaves the question what is space matter? What bends, what expands?

[Halc]

When you look far into space at the most distant visible galaxies, they are all moving away from us and are accelerating away due to the expansion of space.

They're accelerating away due to accelerated expansion, not due to just expansion.  If expansion was constant (not the same as the Hubble 'contant' being an actual constant), a given distant galaxy would be moving away at constant speed, and we'd eventually be able to see it no matter how far/fast that recession rate.

There's a distance beyond which they become invisible because the relative speed between them and us is higher than the speed of light due to the amount of expansion of space between us and them

Not true. There's a distance beyond which they become invisible because they're so young that they don't yet emit light. The most distant light visible is the CMB (material receding at about 3c), and we cannot see beyond that because the universe is opaque beyond that.
The most distant galaxy currently has a recession rate of about 2.3c (and accelerating), although the recession rate was much higher at the time of the emission of the light we see today. This is because the expansion was slowing for a long time, so it was much higher in the distant past, but slower in the near past.

and yet they are not moving through space at a higher speed than c.

Right. More properly worded, no object (not even light) has a peculiar velocity of magnitude greater than c. 'Through space' is ill-defined since it is dependent on the coordinate system of choice.

Here's the response I got from one of the experts here in a pm:-

"The universe is outside the domain of applicability of SR. It's not fantasy and it works perfectly in its domain of applicability."

What is its domain of applicability if it doesn't relate to our actual universe?

SR is a local theory, so it applies only to local spacetime with no significant curvature due to gravity or the general geometry of the universe.  So essentially it works until the curvature differences make a difference in the answer, which is dependent on the precision required for the answer.  SR for instance is totally useless for getting GPS to work, but it's an overkill for getting a man to the moon where Newtonian physics suffices just fine.

Method

We place two clocks a small number of astronomical units apart in reasonably deep space (outside the solar system), both at rest in reference frame A.

This puts them fairly close together in interstellar space. They'll orbit the galaxy like everything else, and switch places now and then, period depending on the orientation of the line drawn between them.  This will not demonstrate expansion at all since they far too embedded in a gravity well.  Newtonian physics is applicable here.  SR seems to have nothing to say in addition to that.

[David Cooper (OP)]

Stick with the question what is space that it can expand at all? Or bend.

That's a big question, and the answer must be that it's more than nothing.

If gravity is impacting on expansion you wouldn't see uniform expansion across the whole universe in all directions it would be more in some directions less in others.

Well, the people measuring it on the large scale say it does appear to be different in different directions, though the values for it in different directions are still similar. It's a story that will likely keep evolving for a long time when it comes to the small details, but that there is substantial expansion is very well established and I don't think that part of the story will change. We can't answer all the questions yet, but we can answer some of them, and the existence of expansion in itself tells us a lot about what's going on, and a lot about what isn't. The more we know, even if it's only a little, the more we can use that to rule out models that don't fit the known facts.

[David Cooper (OP)]

They're accelerating away due to accelerated expansion, not due to just expansion.

It's like compound interest. The expansion creates more space and that space expands too.

There's a distance beyond which they become invisible because the relative speed between them and us is higher than the speed of light due to the amount of expansion of space between us and them

Not true.

It will become the case though, so it is true with the intended but unstated future tense. We're looking back in time towards the big bang and we may now be seeing the past of the most distant galaxies that exist, but if we go on watching them for billions of years, they will disappear from view and we'll no longer be able to see what happens to them after that.

SR is a local theory, so it applies only to local spacetime with no significant curvature due to gravity or the general geometry of the universe.  So essentially it works until...

...until it doesn't fit reality, at which point it is disproved.

This puts them fairly close together in interstellar space. They'll orbit the galaxy like everything else, and switch places now and then, period depending on the orientation of the line drawn between them.  This will not demonstrate expansion at all since they far too embedded in a gravity well.

The clocks are moved in such a way as to prevent that change in orientation during the experiment, and to counter the attraction of the solar system. If we can make measurements with much greater precision, we could reduce the size of the experiment and the amount of time it needs to run for, potentially allowing it to be done much nearer to home still. I've found plenty of expert asserting that the expansion takes place right through where we are, and this can potentially be tested. The people who built LIGO would likely be able to say how close to (or far short of) what's needed we currently have. What they're doing today sounded fanciful a few decades ago, but now that's up and running. This could be the same.