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### Author Topic: Towards measuring the one-way speed of light  (Read 3159 times)

#### CliffordK

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##### Towards measuring the one-way speed of light
« on: 20/01/2012 04:56:30 »
Time, Energy, and the one-way speed of light.

As many of you know, I've been struggling with the idea of measuring the one-way speed of light, and have come to the realization that the measurement has to be done with a single clock, and thus with a mechanically coupled device.  Assuming one can't come up with a better clock not subject to relativity.  I'll endeavor to describe a possible mechanical device to do the measurement.

In a sense, time is inextricably intertwined with space.  Yet, it all depends on the definition of time itself.  With a known reference frame, one can always match one's measurements of time to what is observed in the fixed reference frame.

It seems as if velocity with respect to the “rest frame” is a representation of Kinetic Energy, which then expresses itself in a manner that fouls up our clocks.  In particular, the Kinetic Energy is affecting the energy required to change the hyperfine state of atoms being used in the atomic clocks.  We are ineffective at communicating these changes from location to location as limited by the one-way speed of light without precisely knowing the background velocity of the universe.

At this point, we haven't determined our velocity vector with respect to space, and thus the necessary adjustments to our velocity dependent clocks are impossible to calculate.

It is a good estimate to use the premise that the speed of light is the same in all directions, and likely accurate to about 4 significant figures.  However, a better estimate for the background reference frame might be our velocity vector with respect to the cosmic microwave background radiation, coupled with the orbit of the Earth.  Here are some speed estimates.

300,000,000 m/s: The speed of light:
550,000 m/s: Current Estimates of Milkyway's speed with respect to CMBR:
70,000 m/s: Maximum velocity of Twin Helios at closest approach to the sun.
29,000 m/s: Earth's orbital speed around the sun.
7,000 m/s: Rotational velocity in Low Earth Orbit
3,000 m/s: Rotational velocity of geostationary satellites.
463 m/s: Rotational velocity at the surface of the Earth at the equator.

I believe that we could get a better representation of the one-way speed of light by adding in these correction factors, but the effect is only seen in at most the 4th significant figure with respect to the speed of light.

One option would be to consider the Sun with respect to distant stars as being in a fixed (rest) frame, then the correction factors for everything orbiting the sun would be relatively easy to calculate, in which case the correction factors hits the 5th significant figure.

I don't see the idea of a variable one-way speed of light as necessarily contradicting relativity, but rather augmenting it.

As one's speed approached the speed of light, the one-way speed of light in front of one's ship would appear to approach twice the speed of light, while the that behind the ship would appear to approach zero, with the average speed of light continuing to be the well known c.

Time difference is twice the difference in which the ideal speed of light traverses the differential  locations of the endpoints of the frame shift, and would be essentially constant for a specific velocity of the frame-shift.

One proposition is that we are unable to ever measure the true one-way speed of light, or the true difference in the speeds in opposing directions.  One could still define an arbitrary rest frame, such as our sun, and then expand from there.

However, I believe that we can, in fact, design an apparatus to measure the one-way speed of light to one or two significant figures.  The trick is to design a mechanically operated dual shutter system controlled by a single timing device.

Not finding a difference would assure us that we are not, in fact, on the precipice of a black hole.

However, one likely has to push the device to read out more significant figures (4 or 5) to truly find a difference.

If one can, in fact, measure the speed to one or two digits accuracy, then that just means that we need to push our engineering to capture more digits.

So...  to introduce the
Polarized White Light Split Spinning Shutter Dual Prismatic Interferometer Experiment.
(or more likely UV or X-Ray)

If one uses a spinning shutter connected by a fixed shaft, then one can calculate the one-way speed for light to transverse the gap.

Consider two wheels, each 1 meter in diameter, and separated by 10 meters.  Spin the device at 60,000 RPM, or about 1000 RPS.

For a 3 meter circumference (1 meter diameter), one would get the edges of the wheels spinning at 3,000 m/s.  Whew, that is fast.  It is likely fast enough that it would have to be run in a vacuum.  Perhaps magnetic bearings rather than air bushings.

With light traveling at 300,000,000 m/s, it would take 1/30,000,000 s to cross the 10m gap.

With the wheel spinning at 3,000 m/s, that means the second wheel rotates by 1/10,000 meters, or about 10 microns, which is well within our ability to detect.

Now, the question is to what accuracy could one measure the speed of light.

If Earth's orbital speed is about 29,000 m/s, and the estimate of the Galaxy's movement through cosmic microwave background radiation is about 550,000 m/s, then one might choose a goal of an accuracy of +/- 5,000 m/s, or a total difference in directional speed of 10,000 m/s.

(10,000 m/s) / (300,000,000 m/s) = 0.000033

0.0000333 * 100 micron rotating difference = 0.0033 micron differential = 3.33 nm differential.

That is damned small...  no wonder it wasn't detected earlier.

The wavelength of visible light is about 390 to 750 nm.
Is that a problem?

So...  what can one do to improve the accuracy of the experiment?

Decrease sensitivity goal by a factor of 10.  Some difference should still be detectable.
Increase speed of shutters.  60,000 RPM is already awfully fast, especially for a big piece of equipment, but perhaps it could be pushed up even further.  600,000 RPM?

Making the device longer or bigger in diameter?  Still, it is already pretty unwieldy in specified size, 1meter wheels separated by 10 meters.

My idea is to incorporate a very subtle prism which could say spread out the incoming light by about a micron, or less.  One might be limited by the width of the beam of incoming light, which is likely dependent on the wavelength of the incoming light.  The goal would be to avoid too much overlap of wavelengths.

Then use interferometry to determine the wavelength of the light at the shadow from the spinning wheel.

I am a little mixed on whether I wish to use full spectrum, or some kind of polarized light.  Perhaps one could even use differentiation of coherent waves as part of the manner to exclude certain waves at the boundary, so that longer wavelength light would be selectively directed into the shutter, and shorter wavelength light would be directed between the shutters.

The visible light spectrum still has long wavelengths (390 to 750 nm).  Perhaps one would get some increase in accuracy with intense averaging, as one would get about 1000 readings per second.

UV has a wavelength of 10nm to 400 nm(xenon-mercury short-arc lamps).  X-rays between 0.1nm and 10nm.  One may need to either use UV, or X-Ray spectrum to reduce the wavelength for sufficient accuracy for the measurements.  And, thus, the wheel design should be sufficiently opaque to the desired EM spectrum.  Lead, of course, increases the weight unacceptably, but perhaps one could use some kind of boron doped polymer to construct the wheels, maybe still using a properly counterbalanced lead shutter.

If the device was oriented N/S, in the Northern or Southern Hemisphere, near the 45th parallel, then it would go through about a 90 degree sweep of directions over the course of a day.  Pointing East/West, one would get a 360 degree sweep of directions, including naturally flipping the orientation of the device every 12 hours.  Likely one could catch a diurnal change in the vector motion through space which would be an internal control.  Hopefully it would line up with already predicted planes.  If the accuracy reaches 10,000 m/s, then it would also be able to pick up the motion of the Earth around the sun on an annual basis.  The whole device, of course, could be easily rotated as needed, although it would likely generate a strong gyroscope effect when spinning.  Reversing it 180 degrees would allow a control, as well as effectively reversing the spin direction of the device without needing to reset the shutters.

One might use air bushings, but it is likely that one would need to conduct the experiment in a rarefied atmosphere due to the high speeds involved and air friction, so it leads to the need for magnetic bearings.

The engineering required for this device is intense, but it seems to be within technology that could be built today.  At minimum, it should be able to demonstrate that a one-way delay in the speed of light actually exists.  Hopefully it could be used to measure the speed (or proportional difference) to within 10,000 m/s.

#### Bored chemist

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##### Re: Towards measuring the one-way speed of light
« Reply #1 on: 20/01/2012 06:49:04 »
There are many problems, boron won't help being one of  them.
I think you cannot get interference between beams of oppositely polarised light.

#### CliffordK

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##### Re: Towards measuring the one-way speed of light
« Reply #2 on: 20/01/2012 08:04:46 »
There are many problems, boron won't help being one of  them.
I think you cannot get interference between beams of oppositely polarised light.
Ahhh...
http://www.marshield.com/page/borated-polyethylene-neutron-shielding
They say it is for "high intensity X-Rays", but perhaps that isn't correct.

Nonetheless, if one would make the device, there may be other x-ray shielding materials avialble, or one could design it with a narrow band of lead alloy shielding around the outer parameter of the wheels, and then the rest of the wheels would be made of a lightweight material. The fixed shutter could be made of a more substantial amount of lead.

Actually, tungsten could be used for the ring on the shutters, with good x-ray and longer wavelength shielding, and very high strength for the high-speed application.  And the shutter could be polished very well.  Adjustment of shutter width and offset might be problematic, but not an insurmountable problem.

I don't think I said oppositely polarized light.  However, I have been wrestling on where it would be best to install the polarization for the later interferometer, or ability to determine the wavelength of the resulting light.  That decision could come later.  I initially didn't want the polarization of the waves to interfere with the shutter system, but then later realized that if done right, one might be able to focus it onto the shutters as part of the wave differentiation.  However, that would likely be more important with longer wavelength light.

X-Ray and short UV should be able to be diffracted similarly to visible light, but would need a different system for reading the output.

Perhaps there are electronic analysis methods that could actually create a high resolution quantitative analysis of different wavelengths, and thus would give one a good analysis of the shadows created by the shutters.

Depending on the tools available, one could either do an independent, or a combined analysis of the two sides of the system, as the mechanical shutter system controls the timing, everything else is independent of the precise timing, and thus would not be confounded by the speed of light.  In fact, even the light sources could be independent.

If designed right, the system would be calibrated as a static system, and then evaluated at different system speeds.
« Last Edit: 20/01/2012 08:39:11 by CliffordK »

#### CliffordK

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##### Re: Towards measuring the one-way speed of light
« Reply #3 on: 20/01/2012 23:19:36 »
Ok, I've been thinking about polarization and my experiment a bit more.

Here is what I came up with.

By passing the light through a series of closely spaced vertical slits, it should naturally polarize the light with no additional polarization filter necessary.

The longer wavelength light, however, will be polarized better than the shorter wavelength light.

The longer wavelength light (Red, IR) also gets refracted less by my prisms than the shorter wavelength light (Blue, UV)

I had originally intended to add a slight shutter delay between the two ends of the disk.  However, that becomes an engineering nightmare, in part because the delay has to be opposite for the two ends of the system (directions of the light).

But, if the slits line up, that is no longer an issue.

So, as calculated at 60,000 RPM, the second series of slits should actually hit about 10 microns advanced.

The advancement will cause the second shutter to be at a slightly different angle than the first shutter.  The greater the angle of the second shutter, the more it would naturally select against the longer wavelength light.

That means that the greater the time delay, the longer wavelength light would be selected against by both the position of the shutter with respect to the prism, as well as the angle of the second shutter with respect to the first shutter.

Thus, it would naturally improve the speed discrimination of the system, although it might make the calculations for the actual one-way speed differences more cumbersome.

#### Bored chemist

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##### Re: Towards measuring the one-way speed of light
« Reply #4 on: 21/01/2012 01:20:02 »
FFS!
they say it's for neutrons not X rays.

#### imatfaal

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##### Re: Towards measuring the one-way speed of light
« Reply #5 on: 23/01/2012 17:45:10 »
Time, Energy, and the one-way speed of light.

As many of you know, I've been struggling with the idea of measuring the one-way speed of light, and have come to the realization that the measurement has to be done with a single clock, and thus with a mechanically coupled device.  Assuming one can't come up with a better clock not subject to relativity.  I'll endeavor to describe a possible mechanical device to do the measurement.
Clifford - I don't know if someone has raised these points elsewhere and you have answered them, if so I apologise.  Within modern physics there is no absolute time, and no absolute space.  There is no concept of space that is not relative to something within space that would allow measurement.  There is no undilated time except that within the local frame of reference
Quote
In a sense, time is inextricably intertwined with space.  Yet, it all depends on the definition of time itself.  With a known reference frame, one can always match one's measurements of time to what is observed in the fixed reference frame.
For ease of understanding (and it is not an important distinction) the local frame is fixed - clocks always run quickest in your own frame, ie there is no way to show/prove/test that one's time is being dilated in a black box. upon later comparison then this can be done  when compared to a new frame

Quote
It seems as if velocity with respect to the “rest frame” is a representation of Kinetic Energy, which then expresses itself in a manner that fouls up our clocks.  In particular, the Kinetic Energy is affecting the energy required to change the hyperfine state of atoms being used in the atomic clocks.  We are ineffective at communicating these changes from location to location as limited by the one-way speed of light without precisely knowing the background velocity of the universe.

At this point, we haven't determined our velocity vector with respect to space, and thus the necessary adjustments to our velocity dependent clocks are impossible to calculate.
The only corrections needed are the relative velocities between the clocks - these are well understood and taken account of.  A clock in Boulder, Colorado measured there and then in NIST is at absolute rest for the good folks of Boulder, it is in relative motion when viewed from the GPS clock (which for the LGM sitting on the satellite is also at absolute rest).  SR allows you to define any inertial frame as the rest frame - and no frame is better than another!
Quote
It is a good estimate to use the premise that the speed of light is the same in all directions, and likely accurate to about 4 significant figures.  However, a better estimate for the background reference frame might be our velocity vector with respect to the cosmic microwave background radiation, coupled with the orbit of the Earth.  Here are some speed estimates.
If you don't have this as an axiom then you basically cannot rely on any modern physics

/snipped

Quote
I believe that we could get a better representation of the one-way speed of light by adding in these correction factors, but the effect is only seen in at most the 4th significant figure with respect to the speed of light.

One option would be to consider the Sun with respect to distant stars as being in a fixed (rest) frame, then the correction factors for everything orbiting the sun would be relatively easy to calculate, in which case the correction factors hits the 5th significant figure.

I don't see the idea of a variable one-way speed of light as necessarily contradicting relativity, but rather augmenting it.
We know these correction factors for the movements you have listed - although I wouldn't use the word correction; simply flip them over and ask how we would view a spaceman going at 550kmps - that's how "they would see us"

Quote
As one's speed approached the speed of light, the one-way speed of light in front of one's ship would appear to approach twice the speed of light, while the that behind the ship would appear to approach zero, with the average speed of light continuing to be the well known c.
Completely NO.  Within all frames the speed of light is constant and invariant.

Within the local frame there is no red nor blue shifting which I think this diagram is trying to imply.  When observing from a frame in relative motion then both time dilation and contraction need to be taken into account and I am not sure how you have done this.

Quote
Time difference is twice the difference in which the ideal speed of light traverses the differential  locations of the endpoints of the frame shift, and would be essentially constant for a specific velocity of the frame-shift.
I repeat - all local inertial frame calculation can be made with the utmost assumption that the local frame is at rest, there is no time difference for the two opposite roundtrip paths

Quote
One proposition is that we are unable to ever measure the true one-way speed of light, or the true difference in the speeds in opposing directions.  One could still define an arbitrary rest frame, such as our sun, and then expand from there.

However, I believe that we can, in fact, design an apparatus to measure the one-way speed of light to one or two significant figures.  The trick is to design a mechanically operated dual shutter system controlled by a single timing device.

Not finding a difference would assure us that we are not, in fact, on the precipice of a black hole.
There is no physics that would suggest that any changes would be detected - what ever motion you may imagine for your device, around the world in its orbit, around the sun once a year....drift against the CMBR it is always at rest within the frame from which the measurements are being taken.  Blackhole time dilation is due to position in gravitational potential not relative velocity

#### Costel Munteanu

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##### Re: Towards measuring the one-way speed of light
« Reply #6 on: 24/09/2016 07:13:20 »
One-way speed of light has been finally measured for moving frames of reference and along the gravitational field gradient with a very simple interferometer. Equivalence principle can be tested. The link below provides details
It seems I am not allowed to post links! ? What's this policy?!
But search on LinkedIn profile for  costel-munteanu-4b774931
or try to change the site in between the quotes

#### GoC

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##### Re: Towards measuring the one-way speed of light
« Reply #7 on: 26/09/2016 14:14:37 »
To understand relativity is to understand there is no distance nor time fixed anywhere. Dilation of space causes distances to be measured with different values exactly changing with clocks tick rate to measure the same speed of light in a vacuum. Time and distance measured are always confounded. In SR there is a visual increase in your measuring stick to match the increase in the length of your tick rate which matches the dilation in GR. Its similar to trying to make a perpetual motion machine. impossible! Entropy in mass proves energy does not come from mass but it does from the c in space between mass. We consider the friction caused by mass occupying space as our energy. Mass is a conduit to space energy or fundamental motion. Mass absorbs fundamental energy which dilates the energy of space time. We understand things backwards. Fundamental energy=time =motion c.

#### David Cooper

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##### Re: Towards measuring the one-way speed of light
« Reply #8 on: 27/09/2016 19:11:02 »
The reason experiments of the kind described in this thread fail to produce anything other than a null result is not that the speed of light is always the same in all directions, but that any difference in its speed is hidden by the problem that the apparatus is held together by forces that propagate at the speed of light. The rod connecting the two discs does not maintain their alignment to each other any better than if the discs were on separate axles with their relative alignment being controlled by signals sent between the two discs as radio waves. The the direction of travel through the fabric of space will always change the relative alignment of the discs to maintain the illusion that it is never moving at all.

#### GoC

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##### Re: Towards measuring the one-way speed of light
« Reply #9 on: 28/09/2016 20:19:29 »
If you calibrate your cell path spectrometer on the surface of the moon with a standardized source an then had a hole to the center of the moon you would maintain the same calibration frequency but the cell length would increase in the center of the moon by dilation along with the light wave. They are confounded in every frame and there is no preferred frame.

#### The Naked Scientists Forum

##### Re: Towards measuring the one-way speed of light
« Reply #9 on: 28/09/2016 20:19:29 »