[CliffordK (OP)]

That's not how Relativity was created. SR comes from one idea, a axiom of sorts, still undisputed experimentally.

I suppose it is too early to count one's chickens.
But, the experiment I'm proposing to determine the one-way speed of light... which I think could be calculated to an accuracy of a couple of m/s, would take a huge bite out of Special Relativity.

Or, I suppose, if proved to be negative, could further support the theory.

[David Cooper]

But, the experiment I'm proposing to determine the one-way speed of light... which I think could be calculated to an accuracy of a couple of m/s, would take a huge bite out of Special Relativity.

It won't work - you can't just divide an orbit in two and asume that it takes 11 hours 58 minutes (half the time the Earth takes to rotate) for a geostationary satellite to get from one point to the opposite point and then another 11 hours 58 minutes to get back to the first. The whole system could be travelling close to the speed of light, in which case it will take a very long time for the satellite to travel round the half of the orbit that takes it from behind the Earth to in front of it, and then it will race back the other way in a tiny fraction of the time. While it does this, its clocks will be slowed during the slow half of the orbit and run close to full speed on the way back, making both halves appear to take the same length of time. The result of this is that the effect you're trying to measure will be cancelled out completely and you will detect nothing, just like every other experiment.

[David Cooper]

But it is also so that no matter how fast you move with your 'local clock' it will never change its pace, and according to it your 'aging/decay' will come at a natural pace locally. So what you do there is to assume that there should be some 'global' definition of time. There isn't, and that's one of the things why so many want to get rid of 'times arrow' as a 'global phenomena', because it doesn't exist in reality, only locally.

You are simply asserting that the Einstein's philosophical interpretation is the true one, while I am arguing that the Lorentz interpretation of relativity is correct.

And that you can check very easily using two clocks giving them different 'relative motion'. They will start to differ, but when you reintroduce them into one same frame of reference again (impossible as I think of it for fermions, aka matter) they will share a same 'clock beat' no matter what you measured before between those clocks 'differing', so that is your reality check of what 'times arrow' is, well as I see it.

You can't check it at all easily - any measurements you make fail to determine that one theory is true and the other false. They both remain potentially valid.

Anyway, you wrote "his theory philosophically requires an aether for every possible frame of reference to maintain separations between objects, whereas Lorentz's requires only one."

That's not how Relativity was created. SR comes from one idea, a axiom of sorts, still undisputed experimentally.

'c'.

That and 'frames of reference'

Einstein simply missed it out because it was a problem for the theory that he decided to sweep under the carpet. There has to be a fabric of space which maintains distances between objects in that space - if there was no such fabric, there would be no separation between those objects. Einstein's spacetime can't just be a simple fabric in a single reference frame like ordinary aether, but must be the same in all reference frames, and that requires it to perform some extraordinary tricks, and that's a complex aether whether he likes it or not. A simple aether in a single frame of reference is far more plausible.

It get's worse for Einstein's interpretation, because if the speed clocks run at doesn't actually change, you end up with a universe where light jumps forwards into an unbuilt future in zero time (and covering zero distance too within its frame of reference) to interact with other things that can't possibly be there yet. The attempt to get over this difficulty is to change the whole nature of time such that it is no longer something that runs - you end up with a block universe where it is like an eternal crystal in which light can step from the past straight into the distant future and interact with other items which "took" billions of years to make the same trip.

Imagine a scenario in which we send a radio signal to an alien civilisation forty lightyears away which they have agreed to reply to instantly with a signal of their own which will represent a zero or a one. We will then perform a different action depending on which it is, but this will be combined with a zero (don't invert) or one (do invert) which we will generate here by running a great 80-year-long series of events, each of which will produce a random result which will be the starting point for the next one. The radio signals complete their journeys in zero time within their frames of reference, and because time is never allowed to run slow, these times really do mean zero time. We aren't allowed to use concepts such as "while" unless events are in the same locality, but we can say that all the events that took place through the 80 years here happened while the signal was on its journey. This either means that an astronomical number of sequential events must have run through in zero time (from the signal's point of view, and the signal's point of view is expressly correct), or the future was already in place so that the radio signal was able to take a shortcut into the future with no delay. If you go for the former option, the problem of the great long series of events taking place in zero time introduces a nasty little infinity which perverts the whole idea of time, whereas with the latter option you have no way for the universe to be created in the first place because when you first run it from scratch the radio signal cannot take a shortcut into the future which has yet to be generated. Einstein's interpretation is philosophically bankrupt.

[CliffordK (OP)]

But, the experiment I'm proposing to determine the one-way speed of light... which I think could be calculated to an accuracy of a couple of m/s, would take a huge bite out of Special Relativity.

It won't work - you can't just divide an orbit in two and asume that it takes 11 hours 58 minutes (half the time the Earth takes to rotate) for a geostationary satellite to get from one point to the opposite point and then another 11 hours 58 minutes to get back to the first. The whole system could be travelling close to the speed of light, in which case it will take a very long time for the satellite to travel round the half of the orbit that takes it from behind the Earth to in front of it, and then it will race back the other way in a tiny fraction of the time. While it does this, its clocks will be slowed during the slow half of the orbit and run close to full speed on the way back, making both halves appear to take the same length of time. The result of this is that the effect you're trying to measure will be cancelled out completely and you will detect nothing, just like every other experiment.

It all depends on your definition of time, which I fear has gotten distorted over the past century.   []
I think of time as the rate that the Earth is spinning and orbiting around the Sun (which, of course, does change slightly, so it is good to have an independent measurement).  However, looking at the external Earth and Sun would be invariant in different space frames.  Only if you are in a spaceship leaving Earth, it would appear to slow down due to seeing the light arrive later.  But, the correction is quite simple based on distance from Earth.

One of the places where relativity breaks down is the two-way light beam pointed at a train (which is the classic physicists favorite vehicle).

 [ Invalid Attachment ]

As mentioned earlier, light passing through the open windows of the train in either direction must be unaffected by the motion of the train (at least when running in a vacuum with no compression of gases and etc).

The problem occurs with motion.
Moving towards one light source, and away from a second light source.

Your perception of the speed of the light from the light source you are approaching necessarily speeds up.
Your perception of the speed of the light from the light source behind you necessarily speeds down.

Part of the reason that the light you are approaching has to speed up is that if, for example, you were measuring the passing of light with a series of shutters.  Light would pass through the first shutter, starting the time.  Then your train would move so that the endpoint is closer to the start point, and thus it must arrive at the end point earlier.  Likewise, if the second shutter is receding from the source, the light would arrive at the endpoint later. 

So, if you have two sources of light, then by relativity, for both speeds to be equal, one must have a clock that both runs fast and slow simultaneously. 

[David Cooper]

It all depends on your definition of time, which I fear has gotten distorted over the past century.   []

Time is tightly tied up with the speed of light, but you only get a proper measure of it in the preferred frame - in all other frames you get a slowed aparent time, and you have no way of knowing how fast you are moving relative to the preferred frame. Because the sun is almost certainly moving relative to the preferred frame, using the Earth's orbit as a clock is going to give you an incorrect measure of time, and if you use a clock that sits on the Earth it will run fast for half an orbit and slow for the other half.

However, looking at the external Earth and Sun would be invariant in different space frames.  Only if you are in a spaceship leaving Earth, it would appear to slow down due to seeing the light arrive later.  But, the correction is quite simple based on distance from Earth.

When making a correction, you have to do so with a particular frame in mind, and if you make that the frame of the spaceship, the Earth's orbit will be determined to be increasingly squashed as the speed difference goes up. You will learn nothing from the measurements.

Your perception of the speed of the light from the light source you are approaching necessarily speeds up.
Your perception of the speed of the light from the light source behind you necessarily speeds down.

It would do if you could perceive the speed in a single direction, but you can't - all you perceive is a blue or red shift in the light as it becomes more or less intense.

Part of the reason that the light you are approaching has to speed up is that if, for example, you were measuring the passing of light with a series of shutters.  Light would pass through the first shutter, starting the time.  Then your train would move so that the endpoint is closer to the start point, and thus it must arrive at the end point earlier.  Likewise, if the second shutter is receding from the source, the light would arrive at the endpoint later.

Correct.
 

So, if you have two sources of light, then by relativity, for both speeds to be equal, one must have a clock that both runs fast and slow simultaneously.

What you have to do to solve this problem is deny that the speeds are different in different directions and assert instead that they must actually be the same because they can't be measured in a single direction (this bad philosophy is somehow regarded as science, while superior philosophy is written off as "mere philosophy"). The mantra you must learn to chant is that the speed of light is always the same, so it simply must be the same in both directions (even if it isn't). Having asserted that, you can then employ a trick with the idea of spacetime and have objects that move through space convert some of their distance travelled into a journey through time instead of space. Of course, if all frames were equally valid, none of them would enable their contents to take a shortcut into the future to get there in less time than any other, but it would doubtless be a mistake to attempt to bring reason into this as that would be mere philosophy, and science doesn't do philosophy.

In short, you're right: they have a clock that runs both fast and slow at the same time, but it runs fast in one direction and slow in the other, while only recording time over round trips. The mismatch is hidden from them and can therefore simply be denied - to assert that there must be a difference when it can't be detected is considered to be mere philosophy, and philosophy is out (unless of course it suits them, as it does when it comes to the whole idea that if you can't detect something it means it doesn't exist - that is actually philosophy too, and really bad philosophy to boot, but somehow they regard that bit as science).

[CliffordK (OP)]

To say that the difference between one-way speed of light and two-way speed of light can't be measured, so it falls under philosophy, and does not exist.

But, a variable clock in different frames, as well as a space-time construct that likewise can't be measured falls under true science takes a pretty extraordinary leap of faith.  Especially if you fail to define exactly what "time" is.

I believe that the Opera-Gran Sasso experiment may have inadvertently measured the one-way speed of light.  I have suggested a data analysis which is to plot their times/speeds on a sidereal day that will help confirm this.  And, then later extend it to an annual motion of the Earth.

I've also suggested an experiment that would measure the one-way speed of light in the plane of the Earth (and could easily be extended to other planes).  And, could be correlated with orbital motion of the Earth around the sun...  which gives a known motion with respect to the solar reference frame.

Mark my words!!!!!!
Within the next 10 years, we will have measured the one-way speed of light with respect to Earth's motion, The solar system's motion, and the Milky Ways' motion. 

It will likely bring with it some major changes in Physics, and there will be much more discussion of the "Fabric of Space", and much less discussion of the "Fabric of Space-Time".

[Soul Surfer]

The one way speed of light is in effect measured millions of times by millions of people every day when they make use of the GPS system which is a one way system containing relativistic corrections.  If there was a significant difference from theory it would show up as a systematic error in position measurements according to where you are on the earth's surface.  Even if this error was not noticeable for ordinary navigation it would show up for high precision users.

My understanding of the original question as that it referred to an effect related to the Casimir effect in that if photons travelled between moving conducting plates traveling in different directions which restricted extent of the quantum fields beyond the normal limits if the narrow beam of "photons" would any difference be noticed? This is something quite different.

[CliffordK (OP)]

Let's rule out one possibility first by testing the idea that the speed light travels through the equipment is modified by the speed of the equipment such that it always appears to be the same when measured by the shutter method. Imagine two trains travelling in opposite directions at high speed. Light is sent in the same direction through both trains. Let's put the light source between the trains, then split the beams to send them into the two trains, and then use mirrors to send the light down the middle of the trains. The shutters are moving with the trains. At the end, more mirrors reflect the light back out into the space between the trains where a detector times the arrival of the two beams, where both arrive simultaneously. If the light was actually moving faster in one train than the other, the two beams would not arrive at the same time, but they must do - if they didn't it would be possible to send information faster than the speed of light by sending the message into the other train and transmitting it the length of that train before sending it back into the first train. This means that the shutters should show up something - one of the rear shutters will open and close too soon while the other won't open in time. To any observer on either train though, it will look as if the timing between the shutters opening is wrong, but we can now determine that the timing is right because we synchronised the timers when they were together and then moved then slowly to their positions by the shutters, and confirm it by bringing the timers back together to compare them again.

As far as the original "spinning wheel" experiment that I first suggested, I'm reducing it to the same concept of the two trains with open windows concept, which, according to David, a couple of days ago, would fail to demonstrate a difference between the light paths. There may be a slight gravitational effect which wasn't my goal to find.  I also had hoped to minimize the effect of compression of gasses by using a vacuum.

With the spinning wheels, one could run the test a high velocity, with a small opening, so presumably it could be used to experimentally confirm the two trains hypothesis, but I'm abandoning the direction of inquiry at the moment.

http://en.wikipedia.org/wiki/One-way_speed_of_light#Experiments_that_can_be_done_on_the_one-way_speed_of_light

On the suggestion from yor_on, the "one-way" issue seems to be a much more interesting issue, and thus my interests have shifted.  Potentially the threads should be split if one wants to return to the spinning disk and two train with open windows paradigm, however, I am not seeing significant benefits of following in that direction.

I have found a similar idea to mine suggested by Kolen & Torr, 1982
"An Experiment to Measure the one-way velocity of propagation of electromagnetic radiation."
Foundations of Physics, Vol 12, #3, 1982, p401...
http://www.springerlink.com/content/km33778562kjm410/

Unfortunately I only have the article in abstract form, and can not tell for sure if the experiment was ever conducted.  Anyway, I'll be headed to the local library early next week, and it will give me some bibliographies to bounce around.  Their suggestion was to separate the sender/receiver by less than 1km, generating an accuracy on the order of 100,000 m/s. 

My suggestion with satellite technology, with newer technology, and separating the devices by up to 84,000 km, it drops the error down to the range of 1m/s.

However, right now I'm concentrating on potential flaws in hydrogen or cesium clocks that could effectively reduce the accuracy, thus generating a false negative (or potentially a false positive) result.

Hafele and Keating found a systematic inconsistancy in their atomic clock experiment on the order of +273/-59 nanoseconds, and the GPS system has a systematic inconsistency of about 38 microseconds per day. 

If the inconsistencies are uniform, then the satellite experiment should provide useful data.  However, if the clock inconsistencies are non-uniform, then they could wreck havoc with the experiment.

Obviously the orbital motion of the Earth should provide a much appreciated control for the experiment.

[yor_on]

No David, "You are simply asserting that the Einstein's philosophical interpretation is the true one" isn't the way Einstein did it, as I see it anyway.

What he did was to define lights speed in a vacuum as a constant. From that idea comes both time dilations and Lorentz contractions. Einstein himself wasn't allergic to the idea of an aether, at least not initially. But introducing the constant he found an aether to be unnecessary for defining SR as it wasn't any 'medium' in any ordinary way defining the way those phenomena came to be. Instead it was a natural effect from the concept of that speed of light being the same for all 'frames of reference'. And a frame of reference in this motto is defined from your local reality, all as I see it. As defined by your clock and your ruler relative all other 'frames of reference', then represented by their clocks and rulers.

Lorentz idea was one in where you really had a medium, as a 'resistance' of some sort contracting in some directions but not in others and was created as an explanation to why the MM experiment couldn't find an aether as I remember it.

As for why 'c' is a constant is another question, and one that I have no good answer for, and neither does anyone else, as far as I know? Myself I think of it as a barrier/definer for the place in where we exist, and using it, as well as other constants, we find where the limitations for SpaceTime exist. The problem with those 'constants' is being able to know which ones are valid, it's not easy to see and may also depend on what you define as 'reality'. Most of the ideas that are expressed mathematically do have a groundwork behind them based on axioms. A simple one being one and one is two, but they are what we ground it on, and from them we can define new and different sets of axioms related to different definitions of 'reality'. As in a two dimensional contra a three dimensional geometry, or in Einsteins case, a four dimensional reality.

I think of light as 'clock' primary myself, locally the same wherever you are, or whatever 'speed' you define yourself to have. So split that light in even 'chunks' and you will find that it never change pace for you, meaning that your lifespan always will be what it is. The time dilations you see is always relative your own, local arrow of time. That you can find the twin experiment to make sense is only from a definition in where you share a same original frame of reference (Earth), then your twin accelerate/speeds away to come back to your original frame of reference. Only then, at those relativistic speeds, will you be able to confirm that a 'time dilation' has taken place. It's not as simple as a 'time machine' allowing us to travel forward in time (and as some thinks, backwards) to me it seems more of a geometrical displacement of my 'locality' relative 'the rest' of the universe, if we by geometrical include all 'dimensions' Einstein used, including 'time'.

And that's why I like to look at it from locality, that way I can ignore atether's etc. In my world you have a local clock, defined by 'c', and that constant is the same for us all. We are all 'lighted' by it and it is also what's bringing it all into one whole experience. Because that light you see, and find defining the SpaceTime you observe, present you with one whole 'frame of reference' including everything, but defined locally by your ruler and your clock.

(sorry about the spelling)

[CliffordK (OP)]

I think all current explanations of space has some kind of a background.

Aether/Ether, Fabric of Space, Fabric of Spacetime, etc.

If you were traveling at 3/4 the speed of light (3/4)c, then if the speed of light always looked the same in all directions, one might think that one could accelerate an additional (3/4)c, for a total of 1.5c   []

Imposing some kind of fabric of space, then one can always calculate one's own speed and location with respect to the fabric of space, and thus gets a true physical limit for speed.

Without over-analyzing the supercollider experiments, it seems as if there is, in fact, a universal speed limit in that we are unable to accelerate ions beyond the speed of light.

As far as the Michelson-Morley experiment.

http://en.wikipedia.org/wiki/Michelson-Morley_experiment


What it proved is that the two-directional speed of light is the same in all directions.

I.E.  If you travel X units in the X direction, followed by -X units returning.
And, if you travel Y units in the Y direction, followed by -Y units returning,

Then the speeds are always equal. 

Thus, it just confirms the 2-way speed of light.  It does nothing to prove, or disprove the one-way speed of light, or whether there is, in fact, an ether, or fabric of space.

[CliffordK (OP)]

As far as a light-clock.

It would be pretty easy. 
Unfortunately scientists have intertwined units, time, distance, and the speed of light.

But, for example, one might be able to define the diameter of the helium atom ⁴He as a fundamental distance.  Perhaps add some additional parameters including pressure, and temperature.

Then, one could define a basic unit of time as that time it takes for a two-way light beam to travel the distance of the diameter of helium.

Or...  use the nucleus, if that is more invariable than the electron cloud.

Of course, it might be better to use something a bit bigger like Lead ²⁰⁷Pb.

One alternative would be to define distance by a crystal structure, for example the carbon-carbon distance in diamond, or the ring diameter of benzene or graphene.  Again, under whatever conditions you choose to specify.

[CliffordK (OP)]

Ok, synchronizing clocks is still an issue.
I think there is something to the light clock.

I've made another diagram to study wavelengths and movements.  Mirrors reflect the light waves back towards the source.  Propagation waves shown with respect to the rest frame of the fabric of space.

 [ Invalid Attachment ]

In this example, in all directions the viewer sees green, independent of the actual frame movement.  In fact, it is exceedingly difficult to discriminate between the wavelength/frequency functions (and thus the theory of Relativity).

Say you tuned a frequency discriminator, or perhaps a pair of go/no-go discriminators, like the nanotube in the diagram, so that a single wavelength perfectly went trough the nanotube (or slit, hole, whatever).  Ahead of the light source, light slows down, but the frequency increases, so the resident time in the nanotube in the same frame as the source would be the same.  Likewise, in the reverse direction, the light speeds up, but with a lower frequency.

And, thus the peak to peak time and distance is viewed as the same in all directions.

The good thing is that one can be reasonably certain that the frequency being viewed is the true frequency of the oscillator.

The bad news is that at this point, I can't be quite sure of anything.  So, for example, if I tuned a frequency discriminator, such as comparing a distance like the length/diameter of a nanotube to the desired wavelength, would it be unchanged in orbit?  Or, would, say bondlengths relax as the kinetic energy increases of the atoms (independent of temperature), and it would fool me to think that I needed to slow down the clock due to the higher speed?

[David Cooper]

As far as a light-clock.

It would be pretty easy.

Oh no it wouldn't!

But, for example, one might be able to define the diameter of the helium atom ⁴He as a fundamental distance.  Perhaps add some additional parameters including pressure, and temperature.

Then, one could define a basic unit of time as that time it takes for a two-way light beam to travel the distance of the diameter of helium.

Or...  use the nucleus, if that is more invariable than the electron cloud.

All these things will still be contracted in the direction of travel as the forces that hold them together all travel at the speed of light. Maybe that wouldn't happen if you reached the level of truly fundamental components of matter (at the deepest level where they aren't made up of components themselves), but those may be point sized and have no length to measure.

Ok, synchronizing clocks is still an issue.
I think there is something to the light clock.

I've made another diagram to study wavelengths and movements.  Mirrors reflect the light waves back towards the source.  Propagation waves shown with respect to the rest frame of the fabric of space.

 [ Invalid Attachment ]

In this example, in all directions the viewer sees green, independent of the actual frame movement.  In fact, it is exceedingly difficult to discriminate between the wavelength/frequency functions (and thus the theory of Relativity).

Nice diagram, and it made me wonder for a moment if you can count the crests and troughs of light waves in any way or measure the distance between them to detect the different distances they are actually covering over time in different directions, but of course all that's doing is measuring the frequency of the light which we know varies like that anyway. [Edit: or was I right the first time - it shouldn't be varying even if the experiment is moving if you go by Einstein's interpretation. I've confused myself and need to think about this for a bit longer.] [Edit 2: Or is the diagram wrong - should the waves look identical in both directions?] [Edit 3: No, the diagram's right, but when you try to detect the frequency of the light by its colour it gets "corrected" by the relative movement of the sensor. So, might there be some other way of measuring the peaks and troughs which would allow you to pin down where they are?]

Whatever the case, you've given me an idea. We know that neutrinos keep changing their type as they go along, and they must, I assume, do so after covering set distances through the fabric of space... What I'm wondering is, if you meet a neutrino at higher speeds head-on, how does the extra energy it's carrying show up? Can they carry different energies in such a way that they travel different distances before changing their type? Might there be an opportunity there?

[yor_on]

Clifford, what I see the MMx to do was to confirm light as a constant. The rest is a question of what geometries you choose to describe it in. The one we have is actually easily defined as in having four components. Length, width, height and our arrow of time, or for the theoretical purist, 'time' purely.

There are other definitions of it depending on what geometry you choose to look at it from, but light will still be a constant as far as I can see. You could, if ignoring gravity, create hypothetical situations in where light have different 'speeds' but as NIST proves, gravity and clocks is GR.

[CliffordK (OP)]

If one was thinking about the proposed satellite experiment, then there is a significant speed differential between different motions in the experiment. 

Our current estimates are
At Equator, Earth's rotation velocity is about 463 m/s
At 42,000 km altitude, it would be about 3,053 m/s
Earth's orbital speed is about 29,000 m/s
Estimate of Milkyway's speed vs Cosmic Background radiation is about 552,000 m/s

But I'm assuming the non-linear aspect of relativity wipes out the differences.

One could choose several distant astronomical phenomena, and use them to set one's time, but then one would just be determining one's motion relative to the distant stars, something that we can already do to some extent with redshift/blueshift. 

Anyway, so it is likely that one can not make the determination by using two clocks. 
From this, one might conclude that if the Opera-Gran Sasso experiment was in fact measuring the one-way speed of light, then they may have an error somewhere.

I am working on a design proposal that uses a mechanical connection between two shutters so it only uses one clock.  I'll try to do a few more calculations and refinements and then post it shortly.

[sciconoclast]

Interesting

I was at a conference in July where Dr. Edward Dowdye Jr. demonstrated his "Extinction shift Optical Interferometer " that utilized two rotating disk.  Described as follows: "This experiment will verify a second order effect between two interfering light beams, exhibiting a frequency difference due to an interference in a 3rd frame of reference. The second order effect in the frequency f of the light source is a function of the velocity v of the moving surface of the rotating disk.".

There is of course the Sagnac experiment in which light is sent in different directions between mirrors on a rotating disk.  This produced a phase shift.  When the entire experiment is put in motion there is additional shift.  This led to the development of the laser gyroscope.

There is also the Michelson-Gale-Pearson version in which the spinning Earth itself becomes the disk on which the mirrors are mounted.  There is a null in this version.   However, comparing a difference between a large loop and a smaller loop, with different proportions of the paths aligned to the Earth's rotation, enable the actual rotation of the Earth to be calculated.

The Sagnac experiment involved motion inside the rotating frame of the Earth that was addtional to it where as the M-G-P experiment did not involve any additional motion.

Interestingly in the Hafele-Keating experiment, involving moving atomic clocks the results require the reference frame to not move with the Earth opposite to what is required for the the M-G-P experiment.  When I questioned some experts on this I found that this is because one experiment is determined by general relativity where as the other is determined by the principles of special relativity.  I also learned that the greater their expertise in this area the more they were also concerned by it.

I am not sure any if this is helpful but I hope it is