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Author Topic: What would you see with this dual spinning disk experiment with LIGHT?  (Read 8370 times)

Offline CliffordK

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Ok,
I'm not sure if this has been done before...  so here goes nothing.

There are apparently several experiments that indicate that when light passes through a detector, it is always going the same speed, no matter what the speed or direction the detector is moving.

I'm considering this some kind of "local space" phenomenon, where every object in space creates a bit of local space which dictates the speed of light through that section of space.

So, I'm proposing a dual spinning disk experiment. 



Set this up in a vacuum, so air currents could be avoided, and  would not affect the experiment.  Sorry for the perspective...  shine the light beam from the source, through a beam splitter, then reflect so that it passes through an empty gap between two closely spaced disks, and then into an interferometer.

Alternatively, one could setup a couple of parallel belts to create more resident time/distance in the device.

Setup your interferometer with the disks stopped.  Then turn on your disks.

If spinning clockwise, the right side is moving in the same direction of the light, the side on the left is moving in the opposite direction of the light.

If the speed of light is constant, then nothing would happen.

If the speed of light is determined by the space that it is passing through, then one might expect the light on the right to speed up slightly as it passes through the additive section of the disks, and the speed of light on the left to slow down slightly as it passes through the subtractive section of the disks.

And, thus, one might see a slight shift in the interference pattern.


 

Offline MikeS

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I personally don't think it would make any difference to speed c. (Although with absorption and re-emission it may appear to).  The way I see it is light travels instantaneously in its own reference frame (please excuse my use of inadequate language).  In other words it travels at infinite speed and that infinite speed cannot be added to or subtracted from.
 

Offline RD

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Looks like an experiment to measure "linear frame dragging" …

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Austrian physicists Josef Lense and Hans Thirring … predicted that the rotation of a massive object would distort spacetime metric, making the orbit of a nearby test particle precess. This does not happen in Newtonian mechanics for which the gravitational field of a body depends only on its mass, not on its rotation. The Lense-Thirring effect is very small—about one part in a few trillion. To detect it, it is necessary to examine a very massive object, or build an instrument that is very sensitive.

Linear frame dragging is the similarly inevitable result of the general principle of relativity, applied to linear momentum. Although it arguably has equal theoretical legitimacy to the "rotational" effect, the difficulty of obtaining an experimental verification of the effect means that it receives much less discussion and is often omitted from articles on frame-dragging
https://en.wikipedia.org/wiki/Frame_dragging

https://en.wikipedia.org/wiki/Tests_of_general_relativity#Frame-dragging_tests
« Last Edit: 10/01/2012 08:25:43 by RD »
 

Offline CliffordK

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I personally don't think it would make any difference to speed c. (Although with absorption and re-emission it may appear to).  The way I see it is light travels instantaneously in its own reference frame (please excuse my use of inadequate language).  In other words it travels at infinite speed and that infinite speed cannot be added to or subtracted from.
Except, it isn't quite an infinite speed.  It has been measured to be 299,792,458 metres per second in a vacuum.

The speed varies based on the medium, so it is slower in water than in air.  Varying speed in different mediums is more complicated than absorption/re-emission, as I believe the spectrum isn't changed, except for light that is actually absorbed.  In this case, though, I am proposing to shine the light through a gap between two moving objects, done in a vacuum, hopefully avoiding interference with the medium.

If the observer is moving, then it can be red-shifted, or blue shifted depending on the direction of the observer, but the speed measurement is the apparently the same.  We are also seeing this red-shifting and blue-shifting with the distance and direction of movement of stars.

Anyway, my thought is to essentially have a fixed emitter, fixed observer, but move the "space" between the two.
 

Offline CliffordK

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Looks like an experiment to measure "linear frame dragging" …

Yes...
Thanks for the terminology.

From Wikipedia:
This also means that light traveling in the direction of rotation of the object will move past the massive object faster than light moving against the rotation, as seen by a distant observer.

Much of the Linear Frame Dragging seems to be reported with respect to planetary bodies.  However, the idea is the same, just on a much smaller scale.

The Wikipedia notes seem to imply it involves a massive object...  So, that would bring in a question whether the type of flywheels would be important...  Steel, Aluminum, Carbon Fiber?  Or, if observed, whether the effect would only be related to the gap and speed.
 

Offline MikeS

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I personally don't think it would make any difference to speed c. (Although with absorption and re-emission it may appear to).  The way I see it is light travels instantaneously in its own reference frame (please excuse my use of inadequate language).  In other words it travels at infinite speed and that infinite speed cannot be added to or subtracted from.
Except, it isn't quite an infinite speed.  It has been measured to be 299,792,458 metres per second in a vacuum.

The speed varies based on the medium, so it is slower in water than in air.  Varying speed in different mediums is more complicated than absorption/re-emission, as I believe the spectrum isn't changed, except for light that is actually absorbed.  In this case, though, I am proposing to shine the light through a gap between two moving objects, done in a vacuum, hopefully avoiding interference with the medium.

If the observer is moving, then it can be red-shifted, or blue shifted depending on the direction of the observer, but the speed measurement is the apparently the same.  We are also seeing this red-shifting and blue-shifting with the distance and direction of movement of stars.

Anyway, my thought is to essentially have a fixed emitter, fixed observer, but move the "space" between the two.

We believe that the curvature of space-time is intimately connected with gravity I also believe it is intimately connected with time or more precisely what we call 'time'.  The introduction of the concept of 'time' being what allows us to measure the speed of light as being finite.

To measure 'frame dragging' I imagine the mass of the discs would have to be considerable, likewise their speed.

It's an interesting experiment and sounds simple enough to set up, perhaps someone will do it.
 

Offline yor_on

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Any type of framedragging is the result of gravity, not space by itself. Although it makes sense to wonder considering that without Space's metric, who knows what there is left to measure? Gravity is observer dependent as far as I can see, just imagine what different observers would give differnt positions depending on their relative motion.
 

Offline CliffordK

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If I modified my experiment above...
To include two light speed detectors (however I could make them).
But, put them on the spinning disk itself.



According to General Relativity...  Both speed detectors would measure the speed of light in their spinning disk frame at precisely the "speed of light", C, despite each detector going in the opposite direction at a rapid rate.  There would be some red-shifting or blue-shifting of the wavelength in the spinning disk frame.

So, wouldn't you have to conclude that the light has either slowed down, or sped up in the overall frame.

Back to the original experiment, one option to enforce the "frame" would be to use a glass disk, but that would induce a host of problems, so, I chose to suggest using a vacuum, with a narrow, empty gap between the disks.
 

Offline David Cooper

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According to General Relativity...  Both speed detectors would measure the speed of light in their spinning disk frame at precisely the "speed of light", C, despite each detector going in the opposite direction at a rapid rate.  There would be some red-shifting or blue-shifting of the wavelength in the spinning disk frame.

So, wouldn't you have to conclude that the light has either slowed down, or sped up in the overall frame.

To measure the speed of light you have to make it follow a round trip, so you'd have to intercept some of the light and send it back a bit. You might as well just make some new light for the purpose and time that, but both ways you'll measure it as having the same speed, and it will display the usual speed for light. The rotation will cause horrible problems with the measurements though, so I wouldn't want to try to do the maths.

The light from your source would indeed be red or blue shifted, but that tells you nothing about the speed the light's travelling at - it simply makes the light more or less energetic, although if you know how the light's produced, you'll be able to work out the relative speeds of the emitter and detector.

Quote
Back to the original experiment, one option to enforce the "frame" would be to use a glass disk, but that would induce a host of problems, so, I chose to suggest using a vacuum, with a narrow, empty gap between the disks.

There's something dodgy about the whole idea. Imagine two discs spinning in opposite directions and ask yourself how far from the discs space could be dragged about by the movement of the discs - if they draged the space around them at their own speed, they'd have to slow each other almost to a halt if they got close to rotating at the speed of light. If they only dragged the space they contained, they wouldn't affect each other, and they wouldn't affect passing light either.

You appear to be trying to create an experiment which will make the speed of light conform to the speed of a detector so that the speed is always measured as the same, but it isn't necessary to do that. The speed of light could be enormously higher through the detector in one direction than the other, but that difference will never show up as you can only measure the speed of light over a round trip, the result being that it will be timed as having the same speed in any frame of reference (each frame of reference behaving as if it is the one that the aether lives in, whether or not you want to believe in aether).

By the way, Mike S commented that light travels infinitely fast within its own frame of reference and you corrected him, but he was stating the orthodox position: the idea in the standard model is that light travels instantly over any distance through a vacuum by taking a shortcut into the future. Frame dragging would increase or decrease the distance into the future which the light would jump, but it would still step straight from transmitter to detector covering zero distance and in zero time (ignoring delays at the mirrors and splitters).
« Last Edit: 10/01/2012 19:36:34 by David Cooper »
 

Offline CliffordK

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Surely you don't have to measure the speed of light with a roundtrip back to the source.  But, rather could use an external source like the sun.  I.E.  One should be able to measure the speed of solar light hitting the International Space Station while it is on either the East or West side of the planet.

I believe one method to get an actual measurement of the speed of light is to have it pass through a series of shutters.  Then, calculate the delay between the opening and closing of the shutters, when the light actually passed through.  Perhaps there are better methods now as laser rangefinders are routinely used (slightly different, but similar).

I agree that it may be difficult, but not impossible to put such a device into a rotary platform.  However, on a planetary scale, it could easily be done in the international space station that is traveling 28000 km/h (is that including the rotation of the Earth?), and would either be approaching or receding from the sun or stars.  And, the ISS has a speed differential between itself and the larger planet Earth that it is next to, which could also add variables to the experiment.

The point is that relativity states that wherever we measure the speed of light, it always comes up the same (in the same substance like a vacuum).  So, if we could construct two devices moving in opposite directions, the light speed would still be the same.

It has been a few years since I've studied physics.  The explanation in physics is that the speed of the light isn't changing, but rather time changes, so perhaps this wouldn't show anything.  On the disk, the speed of the disk is uniform, so the time dilation should be uniform?  Only one side is approaching the light source, and one side is moving away from the light source.  The same would be true with the international space station on different sides of the planet.  However, depending on where you are looking, it could simultaneously be approaching the sun, and receding from a star from the opposite direction.  One could design a system to measure the speed of light that would use shutters, but no mirrors or lenses until the light reached its final detector, so it really would not interact with the light until it hit the actual detector.  And, if done right, it could read the speed of incoming light from two opposite directions at the same time.

Your question about sheer factors between contra-rotating disks is interesting.

I can imagine how frame dragging could be a gravitational effect, altering the speed of passing particles.  Does gravity itself rotate?
 

Offline David Cooper

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Surely you don't have to measure the speed of light with a roundtrip back to the source.

I believe one method to get an actual measurement of the speed of light is to have it pass through a series of shutters.  Then, calculate the delay between the opening and closing of the shutters, when the light actually passed through.

Let's try that. How about just two shutters some distance apart, with a light detector at one end. Each shutter is opened for a tiny fraction of a second, so any light that gets to the detector must have travelled through both shutters when they were open.

We can put Joe and Bill in charge of the shutters. They synchronise their watches, and they do this through signals transmitted between them at the speed of light, so if they're moving towards the source, Bill (who is in charge of the first shutter) will open his shutter late and enable the light to get through both shutters even though it is completing the trip from shutter to shutter faster than it would if the equipment was stationary. However, if Bill starts out right next to Joe and they synchronise watches there instead of waiting till Bill is by his shutter, Bill can then make the journey slowly to his shutter without the synchronisation being messed up. He now opens his shutter earlier and the light hits the second shutter while it's shut, thereby demonstrating that it's aparent speed is higher than normal.

I thought I'd gone through all this stuff before and worked out that it couldn't be done, but I can't now remember what it might have been that meant it wouldn't work. What's going on here? An observer watching them at work will determine that Bill's opening his shutter too soon, and this will appear to be confirmed if they compare watches while still at a distance from each other, but when he moves back to where Joe is, their watches say it's the same time.

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.

Let's try to do the original experiment on a larger scale so see if it still makes sense. We have two space ships a lighthour apart - it takes two hours to send a signal from one to the other and back. We don't know if the ships are stationary or moving - they might for all we know be travelling at a substantial proportion of the speed of light, in which case the distance between them might not be as great as we imagine. We can synchronise two clocks on one ship and send one slowly to the other. Ten years later it arrives, but these are accurate clocks and they're still running fine. When ten years have gone by on clocks, signals are sent out at the speed of light to the other ships, so when the signal from the first clock (the clock that didn't switch ships) arrives at the second ship, the second clock should have recorded one hour more than ten years. Will that happen if they're not stationary? If they're actually travelling fast in the same direction as the signal's being sent, it should take longer for the signal to arrive. The second clock's signal should arrive back at the first ship before ten years and one hour have been recorded by the first clock.

Now, if it was that easy, it would have been done, wouldn't it? We would either have detected a preferred frame of reference or found a way to send information faster than the speed of light. Where are the faults in the thought experiments? I'm sure I've been through all this before, but I can't find them this time!
 

Offline yor_on

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No David, I think you're correct. Whenever you measure light there will be gravity involved. In a two way experiment you might say that this phenomena (gravitational time dilations) takes itself out with the light returning, but in a one way experiment that's not possible. And that has been tested already by NIST in their atomic clock experiments on Earth. So with the clocks you use (measuring locally) differing there is no way for A to correlate his definition to B:s without taking into account the gravity differing between locations creating time dilations. There are some ways measuring stars though, not that I remember how for the moment, in where you can find it being a constant.

And that's the whole point of relativity as I see it, not the speed per se, but that it is a 'constant'.



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

Offline David Cooper

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No, it's not about gravity. It's about round trips again. When you take the clock for a walk after synchronising two of them side by side, the walk will affect the time no matter how slowly you move it. You know that the clock will be affected more by moving it if you move it faster, and it's weighted such that it will slow down increasingly more with speed rather than just in proportion to speed, but the length of time you spend moving the clock will also fall increasingly more with speed rather than in proportion to speed because the distance you're taking the clock will contract at higher speeds at exactly the rate required to ensure that no matter what speed you move the clock at you will end up with the same overall slowing (or speeding up) of that clock. This means you might as well just think about moving the clock at the speed of light, which stops time for it completely while its being moved from the rear shutter to the front one, and that is clearly identical to sending a signal on a round trip at the speed of light to synchronise clocks at a distance.

So that's why it fails, and you can't get round it by working out how much you think the clock will have been slowed by the journey either, because you don't know whether the whole experiment is stationary, moving towards the light source or moving away from the light source with the light source chasing after it and gaining on it, in which case when you move your clock from rear shutter to front shutter, more time will pass for that clock rather than less. So it cannot work.
 

Offline David Cooper

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

I've just looked up the link, and a couple of paragraphs down there's something about Lorentz's theory that caught my attention in a big way:-

"In the theory, the one-way speed of light is not, in general, equal to the two-way speed, due to the motion of the observer through the aether. However, the difference between the one-way and two-way speeds of light can never be observed due to the action of the aether on the clocks and lengths. This theory is thus experimentally indistinguishable from special relativity. For reasons of philosophical preference and because of the development of general relativity Lorentz' theory is no longer used."

So it's no longer used for reasons of philosophical preference - not because it's been shown to be wrong. I know it's Wikipedia and can't be entirely trusted, but if this is correct and Lorentz' theory hasn't been knocked down at all, then for philosophical reasons it ought to be the preferred theory rather than Einstein's - his theory philosophically requires an aether for every possible frame of reference to maintain separations between objects, whereas Lorentz's requires only one.
 

Offline CliffordK

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Thanks for all of the comments.
So..  my experiment will fail, as there may be some gravitational dragging of the light photons, but minimal due to small mass. 
The light through the (open) window in the train idea indicates that the speed of light through the middle of the train remains the same.

I think the whole problem with the speed of light being constant boils down to the one-way paradigm.  And, to some extent, that is dependent on our measurement techniques.

So, when we say the speed of light is invariant, it is only in reference to a two-way measurement.

So, if the speed of light from (source --> mirror) is C+X, the speed from (mirror --> source) is C-X, and the average is C.  And, unfortunately we don't know what X is.

One possible frame of reference would be the Cosmic Microwave Background Radiation.  Which, our Universe is is apparently moving through at about 627 km/s
http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation#CMBR_dipole_anisotropy
What angle was that?  Actually, I think the solar system is at a good angle for measurements with respect to the CMBR, but at a bad angle with respect to the orbit around the Milky Way for the next 1/4 orbit.

If the speed of light is in relation to CMBR, then we should see the speed of light being C+627 km/s in one direction, and C-627 km/s in the opposite direction.  That is, unless it is all messed up by the gravity and atmosphere of Earth, and the Solar system, and the Milky Way.

It should be easy enough to do a one-way light experiment in space.

Say you put 2 satellites in geosynchronous orbit, at an elevation of about 42,000 km. 
Two satellites on opposite sides of the globe would be about 84,0000 km apart.

The speed of light is about 300,000 km/sec.

So, your two geosynchronous satellites are about 0.28 light seconds apart. 

Could one find a few km/sec difference in round-trip speeds?  If there is a 600km/sec difference with CMBR...  that is almost a 0.2% difference, and within the realm of what one should be able to measure. 

One trick might be to synchronize the clocks without respect to the CMBR, and the one-way speed of light.  But, this could be done by synchronizing them with respect to a solar eclipse.  You would still have the half degree progression of the solar orbit in a half a day....  but should be able to throw that into one's calculations.

Any pair of satellites that can do a cross communication, having a known orbit should be able to do a similar experiment.  Synchronize their clocks with a known eclipse (Jupiter eclipse, or to one's favorite star whatever), and run satellite to satellite communication pulses. 

Earth is about 150,000,000 km from the sun, or about 500 light seconds.  The Stereo satellites are then about 1000 lightseconds apart, and somewhere around 500 lightseconds from Earth.  Again, one should be able to synchronize clocks with eclipses, and it would be reasonable to measure ship to ship, or earth to ship communications (which already exist).  Hmm, how accurate can we measure these eclipses?  It would probably take a very accurate double-ended telescope that the satellites likely don't have onboard.  But, it should be possible to do so completely independent of the speed of light. 

Once synchronized, the clocks should stay more or less synchronized, so one should be able to repeat the experiment at all angles with respect to the Universe, to get A-->B measurements.  Then half an orbit later, get B-->A measurements with the same clock settings.

Actually, by waiting a half an orbit, one hardly even needs to synchronize the clocks, just compare the speeds in the opposite directions.



So, with our current satellite technology, we should be able to measure the 1-way speed of light with respect to various solar, and universe planes fairly easily, and quite accurately.  Perhaps we already have the data somewhere.

In the chart above...
Set the speed A-->B equal to B-->A 12 hours later.
Compare to the initial speeds B-->A and A-->B 12 hrs later.
 

Offline David Cooper

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I made a mistake a couple of posts ago:-

...the length of time you spend moving the clock will also fall increasingly more with speed rather than in proportion to speed because the distance you're taking the clock will contract at higher speeds at exactly the rate required to ensure that no matter what speed you move the clock at you will end up with the same overall slowing (or speeding up) of that clock.

It isn't that distance that changes, but the internal distances within the moving clock - the clock counts time by using something doing a round trip within the clock. It's hard to get your mind round all this stuff and to keep it there for any length of time, but it always turns out to be impossible to measure the speed of light in just one direction.

So, when we say the speed of light is invariant, it is only in reference to a two-way measurement.

With Lorentz's theory, yes. With Einstein's, probably not - you can play strange philosophical games to twist things such that every frame of reference is effectively a preferred frame at the same time as all the others such that the speed of light is the same in both directions in all frames. It doesn't actually work (it strips real time out of the model and leaves you with universes which can't be generated in any rational way), but a lot of people think it does.

Quote
One possible frame of reference would be the Cosmic Microwave Background Radiation.

You can't make assuptions though - the content of the universe could have begun with a spin relative to the fabric of space.

Quote
It should be easy enough to do a one-way light experiment in space.

I wish it was.

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Say you put 2 satellites in geosynchronous orbit, at an elevation of about 42,000 km. 
Two satellites on opposite sides of the globe would be about 84,0000 km apart.

The speed of light is about 300,000 km/sec.

So, your two geosynchronous satellites are about 0.28 light seconds apart.

That distance will be contracted when aligned with the direction of travel of the Earth, so you don't know how far apart they really are. Again you have to synchronise the clocks on them, and if you do that at a distance you'll have a mismatch in the timings that completely cancels out the effect you're trying to detect, while if you synchronise them together before sending the satellites to their positions for the experiment, the journeys they take to get there will affect the clocks in such a way that the syncronisation will be affected in an identical manner to the one you get using the other method.

Quote
One trick might be to synchronize the clocks without respect to the CMBR, and the one-way speed of light.  But, this could be done by synchronizing them with respect to a solar eclipse.  You would still have the half degree progression of the solar orbit in a half a day....  but should be able to throw that into one's calculations.

If you rotate a disk while the disk moves along through the aether, the side rotating in a forwards direction will rotate more slowly than the side moving backwards (imagine a disk moving at half the speed of light and rotating such that the edge also rotates at half the speed of light - the edge going forwards will fall short of the speed of light). The whole disk distorts, with more material on one side than the other. It is impossible to detect these distortions for the usual reasons - your measurements are affected by things that all happen at the speed of light, so everything is cancelled out to the point where it looks totally normal. The result of this is that you can't assume that half of a circular orbit takes half the time of the other half of the orbit.

Quote
Synchronize their clocks with a known eclipse (Jupiter eclipse, or to one's favorite star whatever), and run satellite to satellite communication pulses.

You can't judge the timings and distances properly (they're affected by your speed of travel through the aether), so it's a non-starter. The effects of relativity make for the most amazing story, with everything conspiring against you being able to measure your speed of travel through the aether. Sadly, instead of marvelling in this phenomenon, the standard approach is to push Einstein's warped interpretation and make physics look like witchcraft - that all frames of reference are equally valid and that there is no aether.
 

Offline CliffordK

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There are a few issues with the speed of light.
Contraction, time, whatever.
One-Way-Frame.

The big issue with the one-way-frame is that one can assume an X and Y components of the speed of light:

C+x/C-x & C+y/C-y

For now, let's just consider the X component.

The average round-trip speed of light remains as C, and would be calculated as the average speed of light by: ((C+x)+(C-x))/2



So..  the neat thing about geosynchronous satellites is that everything reverses every 12 hours.  Considering two satellites nearly across from Earth, but off enough to send inter-satellite communications.

Consider separate clocks:
TA0 & TB0

Now, consider the time from satellite A to B at time T0 to be:
TAB0 = TB0-TA0+C+X0
And the time from satellite B to A to be:
TBA0=TA0-TB0+C-X0
With the roundtrip time being:
TAB0 + TBA0 = ((TB0-TA0+C+X0) + (TA0-TB0+C-X0)) = 2C

Twelve hours later, the satellites have completed a half rotation around the planet (TA12 & TB12) where TA12 = TA0 + 12 hrs and TB12 = TB0+12 hrs

TAB12=TB12-TA12+C+X12
And the time from satellite B to A to be:
TBA12=TA12-TB12+C-X12

If you substitute in the equations above:
TA12 = TA0 + 12 hrs and TB12 = TB0+12 hrs

The 12 hrs cancels out, and you get:

TAB12=TB0-TA0+C+X12
And the time from satellite B to A to be:
TBA12=TA0-TB0+C-X12

Now... 
If you set:
X12 = - X0  (reversed the direction of the travel):

One gets:
TAB12=TB0-TA0+C-X0
And the time from satellite B to A to be:
TBA12=TA0-TB0+C+X0

Now, you can add the equations together.
Now, consider the time from satellite A to B at time T0 to be:
TAB0 = TB0-TA0+C+X0
plus
The time from satellite B to A, 12 hrs later.
TBA12=TA0-TB0+C+X0

TAB0 + TBA12 = 2C+2X

And.
And the time from satellite B to A to be:
TBA0=TA0-TB0+C-X0
plus (TAB12=TB0-TA0+C-X0)

TBA0 + TAB12 = 2C-2X

Hmmm  I have to be getting close to a conclusion somewhere.
And, indeed I am (I think).  Considering my instantaneous round trip times calculated above:
TAB0+TBA0 = 2C = TAB12 + TBA12

So, let me subtract the instantaneous times from the 12 hr times, and I get:
TAB0 + TBA12 = 2C+2X
minus (TAB0+TBA0 = 2C)

TBA12 - TBA0 = 2X

and

TBA0 + TAB12 = 2C-2X
minus (TAB0 + TBA0 = 2C)

TAB12 - TAB0 = -2X

So..
With that page full of equations
And my vain attempt to remember elementary algebra.

I conclude that any difference in times from Satellites A to B, and that seen from A to B, 12 hrs later is twice the difference due to the one-way difference in time.

Now, I've written all this with TIMES, including simplifying the time for the two-way transit of light, C.

However, one could use one of many ways to convert it to either a portion of the speed of light (C/X), or distances and an actual velocity.

I've also only calculated the X component.
The Y component would be calculated 6 hours later.
Or...  more likely, one would do continuous calculations, to calculate the maximum and minimums for these values, and thus discern a speed and direction (with respect to Earth's axis plane) of the movement through space/aether.

Radio waves and light waves are essentially the same, and should be able to be used interchangeably.  The most accurate clocks and timing systems would be useful, but one could probably use a fairly crude system, at least for preliminary calculations.

With a pair of polar satellites in the same orbit, one could do these calculations in a 3-D reference plane, especially since the polar orbits precess, one could build a nice 3-D model of one-way speed of light frame slippage.

Solar orbiting satellites with about a 365 day orbit could also be used with either solar satellite to Earth calculations, or between a pair of satellites.

Now, if all of the one-way times came up equal, that would certainly be an important negative result, but one has to do the test.
« Last Edit: 12/01/2012 21:55:19 by CliffordK »
 

Offline CliffordK

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The biggest issues with all the above is if the clocks can not tick out 12 hrs, and reproduce the transit times with an offset of 12 hrs.  Obviously reproduced again at 24, 36, 48, 60, 72 hrs, etc.

I.E.  If your clocks run slower on one side of Earth's orbit, and faster on the other side of Earth's orbit. 

But, one should be able to reproduce the calculations with multiple satellites in different orbits, and different orbital velocities around different objects.
 

Offline yor_on

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David, I agree in that relative motion will create 'havoc' also, when comparing between 'frames of reference'. 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. 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. The thing I find very interesting with gravity is that it somehow becomes as a 'frozen' form of 'relative motion/acceleration', existing everywhere there is a SpaceTime, no matter how weakly expressed.
 

Offline yor_on

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Relative motion and acceleration isn't really the same in relativity, but they still must be in some strange way, as it seems to me? They will both describe displacements.
=

David, as you point out. You have to take wikipedia with some pinches of salt :) I think there was some warning notion at the start of that article too? 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'
« Last Edit: 13/01/2012 15:05:04 by yor_on »
 

Offline CliffordK

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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.
 

Offline David Cooper

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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.
 

Offline David Cooper

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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.

Quote
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.
« Last Edit: 13/01/2012 20:08:53 by David Cooper »
 

Offline CliffordK

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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).



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. 
 

Offline David Cooper

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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.

Quote
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.

Quote
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.

Quote
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.
 
Quote
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).
 

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