# Experiment to determine the one-way speed of light

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#### butchmurray

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##### Experiment to determine the one-way speed of light
« on: 18/11/2012 11:16:18 »
Experiment to determine the one-way speed of light
The Murray Experiment MMXII
By Thorntone E. Murray
November 17, 2012

Brief description:
For a light pulse that is reflected directly back to its source, the time duration of the light pulse is acquired in the direction ‘to the reflector’. The time duration of the reflected light pulse is acquired in the direction ‘from the reflector’. These two time durations for the light pulse are averaged. The average time duration (t) is then multiplied by the speed of light (v) (299,729,548 m/s). Per the speed equation (d=vt), the result is the length of the light pulse (d), which is the same for each direction.

With the length of the light pulse known and the time duration of the light pulse known for each direction, the length of the light pulse (d) divided by the time duration of the light pulse (t) for each direction yields the speed of light (v) for each corresponding direction per the speed equation (v=d/t). If the time duration of the light pulse is the same for both directions, the speed of light is the same in both directions.

Operation:
The light pulse source produces a light pulse of appropriate time duration.
The photo-detector produces an “up” signal when the leading edge of the ‘to the reflector’ direction light pulse reaches it. This first signal starts the timer. The arrival time of the signal is recorded.
The photo-detector produces a “down” signal when the trailing edge of the ‘to the reflector’ direction light pulse reaches it. The arrival time of the signal is recorded.
The light pulse reaches the reflector and is reflected back to the photo-detector.
The photo-detector produces an “up” signal when the leading edge of the ‘from the reflector’ direction light pulse reaches it. The arrival time of the signal is recorded.
The photo-detector produces a “down” signal when the trailing edge of the ‘from the reflector’ direction light pulse reaches it. The arrival time of the signal is recorded and the timer is reset.
The process is repeated the number of times required to obtain statistically valid results.

Calculation:
The duration of time from the first “up” signal to the first “down” signal is the time duration of the pulse for the direction ‘to the reflector’, t(o).
The duration of time from the second “up” signal to the second “down” signal is the time duration of the pulse for the direction ‘from the reflector’, t(r).
These two time durations for the light pulse are averaged.
The average of the time durations, t, is then multiplied by the speed of light, v, (299,729,548 m/s).
The result is the length of the light pulse, d, per the speed equation (d=vt).
The length of the light pulse, d, divided by the time duration of the light pulse in the direction ‘to the reflector’, t(o), yields the speed of light, v(o), for the direction ‘to the reflector’ per the speed equation (v=d/t).
The length of the light pulse, d, divided by the time duration of the light pulse in the direction ‘from the reflector’, t(r), yields the speed of light, v(r), for the direction ‘from the reflector’ per the speed equation (v=d/t).

Formulation:
t(o) - the time duration of the light pulse in the direction ‘to the reflector’
t(r) - the time duration of the light pulse in the direction ‘from the reflector’
t – the average of the time durations of the light pulse in both directions
v(o) – the speed of light in the direction ‘to the reflector’
v(r) – the speed of light in the direction ‘from the reflector’
v – the average speed of light, 299,792,548 m/s
d – the length of the light pulse

t=(t(o)+t(r))/2   the average of the time durations of the light pulse
d=299,792,548*t   the length of the light pulse  vt=d
v(o)=d/t(o)   the speed of light in the direction ‘to the reflector’  d/t=v
v(r)=d/t(r)  the speed of light in the direction ‘from the reflector’  d/t=v

Examples:
A. Rotational speed + orbital speed of earth at equator at midnight local time
t(o)=.000003328876s   t(r)=.0000033290614s
t=.000003328876+.0000033290614/2=.0000033289688s
d=299,792,548*.0000033289688=998m
v(o)=998/.000003328876=299800903.1m/s
v(r)=998/.0000033290614=299784192.9m/s
Proof – v(o)+v(r)/2=v  299800903.1+299784192.9/2=299,792,548m/s

B. Rotational speed of earth at equator at 0600hrs and 1800hrs local time
t(o)=.0000050434796s  t(r)=.0000050434955s
t=.0000050434796+.0000050434955/2=.000005043488s
d=299,792,548*.000005043488=1512m
v(o)=1512/.0000050434796=299793013.1m/s
v(r)=1512/.0000050434955=299792082.9m/s
Proof – v(o)+v(r)/2=v  299793013.1+299792082.9/2=299,792,548m/s

With the information provided herein, those skilled in the art and having the necessary technical expertise are able to construct an apparatus capable of performing the functions described.

Thorntone E. Murray
butchmurray
November 17, 2012
I was not smart enough to know it was impossible to do what I did.

#### David Cooper

• Neilep Level Member
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##### Re: Experiment to determine the one-way speed of light
« Reply #1 on: 19/11/2012 01:06:48 »
I may have missed the point, but it sounds as if you're sending out a pulse of light and timing the length of that pulse rather than the time it takes to travel anywhere. If that is indeed what you're doing, it will be the same time interval whether measured at the source on emission, at the mirror on reflection, and on detection back at the source. I can't see how you're going to get any useful information out of that.

#### butchmurray

• Sr. Member
• 194
• If I had my druthers, I would have druthers
##### Re: Experiment to determine the one-way speed of light
« Reply #2 on: 20/11/2012 00:53:38 »
You are correct in that the length of the light path is not a consideration. It does have to be more than twice the physical length of the light pulse. It is the time duration of the light pulse that is measured in each direction.

If those time durations of the light pulse are exactly the same in both directions for multiple orientations there is no need to carry the experiment any further. That would prove, by experiment, that the speed of light is the same in all directions.

However, if the time duration of the light pulse is ever not the same for both directions that would prove that the speed of light is not the same in both directions and a new era in physics will begin.

Thanks,
Butch
I was not smart enough to know it was impossible to do what I did.

#### zordim

• Jr. Member
• 46
##### Re: Experiment to determine the one-way speed of light
« Reply #3 on: 20/11/2012 12:50:29 »
The speed of light is determined with the $$\epsilon$$ and $$\mu$$ properties of space. These properties are affected by the presence of matter. Within the matter (among atoms), $$\epsilon$$ and $$\mu$$ properties have higher values. Outside matter, these values decrease with the distance from material object, more or less rapidly, depending on the objects mass and density.
The increase of $$\epsilon$$ and $$\mu$$ properties occurs when two EM-energy flows confront each other. The most elementary EM-energy flow confrontation is the confrontation of two photons. The most elementary matter-particle is the two-photons-whirl (electron, positron, quarks, antiquarks). The clear and bright unification of physics is presented in http://www.thenakedscientists.com/forum/index.php?topic=46034.0
You are welcome to judge it.

#### butchmurray

• Sr. Member
• 194
• If I had my druthers, I would have druthers
##### Re: Experiment to determine the one-way speed of light
« Reply #4 on: 20/11/2012 20:48:06 »
Zordim,

That will ensure we are all on the same page. I am looking forward to reading it.

Thank you,
Butch
I was not smart enough to know it was impossible to do what I did.

#### David Cooper

• Neilep Level Member
• 1505
##### Re: Experiment to determine the one-way speed of light
« Reply #5 on: 20/11/2012 21:35:39 »
If the speed of light is different in different directions, there is no way to measure that as you can't time it usefully over a one way trip. The duration of a pulse of light will be the same whether the speed of light is identical in both directions or radically different. Imagine two runners covering a course at the same speed, but not starting together. The first runner leaves ten seconds before the other and arrives at the finish line ten seconds before the other. Now turn the track into a moving one so that the runners have to run further or less far in order to get from the start to the finish and it makes absolutely no difference to the time interval between them either at the start or at the finish. The physical length of your light pulse also has no impact on the timings.

#### butchmurray

• Sr. Member
• 194
• If I had my druthers, I would have druthers
##### Re: Experiment to determine the one-way speed of light
« Reply #6 on: 25/11/2012 14:12:46 »
The following is a brief explanation of the basic operation of the preferred embodiment. This is a very basic description that should address most questions concerning feasibility of the experiment.

Preferred Equipment, of specifications that meet experiment requirements:
Ultraviolet laser
Ultraviolet light detector
Light collimator
Clock - precise to 10 picoseconds with appropriate inputs and outputs
Data processor
Reflector(s)
Unobstructed light path of greater than 1000 meters; oriented due east or due west if a single reflector is used or at least one in either of those directions for multiple reflectors

Basic Operation:
Light pulse:
1. The laser emits a light pulse of 3 microseconds plus or minus 500 nanoseconds through a collimator in the direction “to reflector”
2. The light detector mounted in the collimator detects the leading edge of the light pulse in the direction “to reflector” and outputs signal “A” to the clock
3. The light detector detects the trailing edge of the light pulse in the direction “to reflector” and outputs signal “B” to the clock
4. The light pulse reaches the reflector and is reflected directly back to the collimator
5. The light detector mounted in the collimator detects the leading edge of the light pulse in the direction “from reflector” and outputs signal “C” to the clock
6. The light detector detects the trailing edge of the light pulse in the direction “from reflector” and outputs signal “D” to the clock

Processing:
1. The clock outputs the time of receipt of signals “A”, “B”, “C” and “D” to the processor where all clock outputs are stored.
2. The processor subtracts the time of receipt for signal “A” from the time of receipt for signal “B”. The result is t(o), the time duration of the light pulse for the direction “to reflector”. This and all results of computations are stored for future use.
3. The processor subtracts the time of receipt for signal “C” from the time of receipt for signal “D”. The result is t(r), the time duration of the light pulse for the direction “from reflector”.
4. The processor averages the 2 time durations and multiplies the result by the speed of light, 299,792,548. The result is the average length of the light pulse, d, per the speed equation d=vt.
5. The processor divides d by t(o). Per the speed formula expressed as d/t=v. for this case d/t(o)=v(o), v(o) is the speed of light for the direction “to reflector”.
6. The processor divides d by t(r). Per the speed formula expressed as d/t=v. for this case d/t(r)=v(r), v(r) is the speed of light for the direction “from reflector”.

Notes:
v(o) and v(r) produce the average 299,792,548m/s only if the time duration of the light pulse is the same in both directions, in which case the speed of light is the same in both directions.

The physical length of the light path, from the detector to the reflector and back to the detector, must be greater than twice the average physical length of the light pulse. The exact length of the light path is not an issue.

For this embodiment of the experiment a minimum light path length of 1000 meters from the detector to the reflector is suggested for a resolution of 10 picoseconds total difference in the time durations of the light pulse for both directions. For multiple light paths it is immaterial if the reflectors are unequal distances from the detector.

The number of cycles of the experiment necessary for statistical validity is determined by the individual circumstances of each case.

Please disregard the examples in the original post as they are in error. I apologize.
The following examples utilize a pulse length of 1000 meters to draw attention to various relationships in the data. The actual pulse length is calculated for and used in each individual cycle of the experiment so reasonable variations of pulse length are not an issue.

Formulation:
t(o) - the time duration of the light pulse in the direction ‘to the reflector’
t(r) - the time duration of the light pulse in the direction ‘from the reflector’
t – the average of the time durations of the light pulse in both directions
v(o) – the speed of light in the direction ‘to the reflector’
v(r) – the speed of light in the direction ‘from the reflector’
v – the average speed of light, 299,792,548 m/s
d – the length of the light pulse

t=(t(o)+t(r))/2   the average of the time durations of the light pulse
d=299,792,548*t   the length of the light pulse  d=vt
v(o)=d/t(o)   the speed of light in the direction ‘to the reflector’  v=d/t
v(r)=d/t(r)  the speed of light in the direction ‘from the reflector’  v=d/t

Examples:
A. The speed of light same in both directions
t(o)=.000003335640s  t(r)=.000003335640s
t=.000003335640+.000003335640/2=.000003335640s
d=299,792,548*.000003335640=1000m
v(o)=1000/.000003335640=299792548/s
v(r)=1000/.000003335640=299792548/s

B. Orbital speed of earth at 0000hrs and 1200hrs local time
t(o)=.000003335308s   t(r)=.000003335971s
t=.000003335308+.000003335971/2=.000003335640s
d=299,792,548*.000003335640=1000m
v(o)=1000/.000003335308=299822348m/s
v(r)=1000/.000003335971=299762748m/s

Butch
I was not smart enough to know it was impossible to do what I did.

#### David Cooper

• Neilep Level Member
• 1505
##### Re: Experiment to determine the one-way speed of light
« Reply #7 on: 25/11/2012 20:37:26 »
I still don't understand how the length of the light pulse is going to last different amounts of time when all the components of the apparatus used in the experiment are stationary relative to each other. You're trying to measure time differences that won't exist and that shouldn't exist.

#### butchmurray

• Sr. Member
• 194
• If I had my druthers, I would have druthers
##### Re: Experiment to determine the one-way speed of light
« Reply #8 on: 28/11/2012 06:28:02 »
A light pulse is emitted from a source and reflected directly back to that source. There is a single detector in the path of the light pulse that causes a clock to run as long as the light pulse is present at the detector. The amount of time the light pulse is present at the detector is the time duration of the light pulse.

The clock measures the time duration of the light pulse when the light pulse goes to the reflector. The clock measures the time duration of that light pulse again when the light pulse comes back from the reflector. So, the time duration of that light pulse is measured twice.

If the measured time duration of the light pulse IS the same for both directions, the speed of light IS the same for both directions. If the measured time duration of the light pulse is NOT the same for both directions, the speed of light is NOT the same for both directions.

Ideally all of the components of the experiment, other than the reflector(s), are a single main assembly that can be pointed in any direction. The reflector(s) can be located east, west, north, or any other direction in relationship to the main unit. As long as the distance to the reflector(s) is further than the physical length of the light pulse, the actual distance to the reflector(s) does not matter.

For ease of understanding this operational description differs slightly from the previous one but the result is the same.

Thanks,
Butch
I was not smart enough to know it was impossible to do what I did.

#### David Cooper

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• 1505
##### Re: Experiment to determine the one-way speed of light
« Reply #9 on: 28/11/2012 20:11:29 »
If the measured time duration of the light pulse IS the same for both directions, the speed of light IS the same for both directions. If the measured time duration of the light pulse is NOT the same for both directions, the speed of light is NOT the same for both directions.

Asserting that again doesn't make it true. If the speed of light is faster in one direction than the other, it will have a longer wavelength going one way than the other, but the duration of the pulse will be exactly the same. You need to switch to trying to measure the wavelength of the light, but you can't do that unless you can introduce a stationary detector into the experiment, which could be done by luck, but you wouldn't be able to tell if it is stationary.

#### butchmurray

• Sr. Member
• 194
• If I had my druthers, I would have druthers
##### Re: Experiment to determine the one-way speed of light
« Reply #10 on: 29/11/2012 19:59:14 »
Quote
Asserting that again doesn't make it true. If the speed of light is faster in one direction than the other, it will have a longer wavelength going one way than the other, but the duration of the pulse will be exactly the same. You need to switch to trying to measure the wavelength of the light, but you can't do that unless you can introduce a stationary detector into the experiment, which could be done by luck, but you wouldn't be able to tell if it is stationary.
?

Thanks,
Butch
I was not smart enough to know it was impossible to do what I did.

#### David Cooper

• Neilep Level Member
• 1505
##### Re: Experiment to determine the one-way speed of light
« Reply #11 on: 29/11/2012 21:17:27 »

Picture a treadmill a hundred metres long (meaning that there's a little bit over 200m of track in a loop). If you run along that track while it's switched off, it takes you ten seconds to cover the distance because you're a good runner with an added superpower: you can accelerate from zero to full speed instantly like a photon, though I suspect that photons are already moving at c even before they're emitted.

If the machine is now switched on so that the track is moving towards you as you run along it, and the speed of the track is half of your running speed, what will that do to your time? It will clearly take you 20 seconds instead of 10. If you then run back along it in the other direction it will take you 6.67 seconds.

Now repeat that, but get a bunch of friends to do it with you, setting off at one-second intervals. You'll find that they also arrive at the finish at one-second intervals and that they pass any marker at the side of the track (not on the track, but stationary beside it) at one-second intervals. All the detectors in your experiment with light would measure your light pulses as having the same duration for the same reason.

Now think about the distribution of the people running on the track. When they're going against the movement of the track, they'll be closer together, but when the track's going the same way they are, they'll be further apart. This is equivalent to the peaks and troughs of the waves of light in your experiment - the wavelength of the light is changed, except it's more complicated as the timers are slowed down and the wavelength is affected by that too (because the track represents a fabric of space through which the timers would also be moving).

If you try to measure the frequency of the light, you will normally do so using something which is moving through space at the same speed as the emitter and reflector, so they detect the same wavelength regardless of which way the light comes towards them. You can only measure the true wavelengths of the light if you use a detector attached to the track (which means stationary in the fabric of space). When you're working with space though, you can't detect the track or tell which way it's moving relative to you, and because all your measuring equipment is governed by the speed of light, everything is slowed down by movement in such a way as to maintain the undetectability of the fabric of space so that you can't tell if you're moving through it, or how fast, or in which direction.

#### butchmurray

• Sr. Member
• 194
• If I had my druthers, I would have druthers
##### Re: Experiment to determine the one-way speed of light
« Reply #12 on: 22/01/2013 22:26:38 »
FOR THE RECORD

An experiment that ascertains the one-way speed of light

Rationale:
For a light pulse (e.g. a burst of light from a laser) that is reflected directly back to its origin the physical length of that light pulse, without exception, is equal in both directions. If the time duration of that light pulse is equal in both directions, the speed of light is equal in both directions. If the time durations of that light pulse are not equal in both directions, the speed of light is not equal for both directions.

When the physical means that detect and measure the time durations of the light pulse in each of the opposite directions are one and the same in all respects the clock synchronization issue as well as any gravity issues are eliminated and there can be no doubt as to the absolute validity of the results of calculations based on those measurements.

Operation:
An apparatus emits a light pulse (a burst of laser light) that is reflected directly back to the apparatus.
The apparatus measures the time duration of the emitted light pulse before it is reflected.
The apparatus measures the time duration of that light pulse after it is reflected.
The physical means that detect and measure the time durations of the light pulse in each direction are one and the same in all respects.
The calculations carried out by the apparatus based on the measured time durations of the light pulse for each of the opposite directions produce the one-way speed of light for each direction.
The process can be repeated as many times as necessary to ensure validity.
NOTE: The length of the light path is not used in any of the calculations in the experiment. However, the length of the light path must be at least twice the physical length of the light pulse plus the distance light propagates during the latency time of the circuitry in the apparatus.

Figures:
FIGURE 1: The progression of the calculations:
The measured time duration of the emitted light pulse is t(e).
The measured time duration of the reflected light pulse is t(r).
The two-way speed of light is constant, v(avg). In a vacuum, it is 299,792,548 m/s (in air, it is 299,702,637 m/s).
Figure 1- Fig. 1A – KNOWN VALUES THUS FAR: v(avg), t(e) and t(r)
The formula for average speed solved for (d(e)+d(r)) is v(avg)*(t(e)+t(r))=(d(e)+d(r)).
The apparatus performs the calculations.
The physical length of the reflected light pulse, d(r), is equal to the physical length of the emitted light pulse, d(e). Then, (d(e)+d(r))=2d. The length of the light pulse is then d in each direction.
Figure 1- Fig. 1B – KNOWN VALUES THUS FAR: v(avg), t(e), t(r), (d(e)+d(r)) and d
The speed formula solved for v is d/t=v.
The apparatus performs the calculations for each direction.
Figure 1- Fig. 1C – ALL VALUES ARE NOW KNOWN: v(avg), t(e), t(r), d for the light pulse in each direction and v for the light pulse in each direction

FIGURE 2: Equal time durations for both directions
Fig. 2A, 2B and 2C demonstrate that in the circumstances for which the time duration (t) of the light pulse is the equal for the two directions. The speed of light is, necessarily, equal and is 299,792,548 m/s in each direction.

FIGURE 3: Hypothetically detecting the earths rotational speed only
Fig. 3A shows the difficulty of detecting this relatively minute speed difference with a short pulse width, d. Fig 3B and 3C demonstrate the time precision necessary decreases with increased pulse widths.

FIGURE 4: Hypothetically detecting the earths orbital speed only
Fig. 4A and Fig. 4B demonstrate what could be two consecutive pulses that are nearly the same length (pulse width, d). The difference in the length is compensated for by the experiment. Fig. 4C demonstrates the effect of substantially longer pulse widths on the degree of time precision required. Using pulses reflected off a reflector left on the moon should be considered.

Implementation:
FIGURE 5: Simplified block diagram of an embodiment

There will almost certainly be some technical issues but none should be insurmountable.

Thank you,
Thorntone ‘Butch’ Murray
I was not smart enough to know it was impossible to do what I did.

#### David Cooper

• Neilep Level Member
• 1505
##### Re: Experiment to determine the one-way speed of light
« Reply #13 on: 23/01/2013 19:34:03 »

You cannot get movement of this apparatus to show up anything at all. If you move it, the length of a wave will change and the clocks will slow, so the pulse of light will take longer to be emitted but will be measured by the clocks as being the same as normal. Because the mirror is moving with the apparatus, it will put exactly the right correction on the light for the speed it's moving at to ensure that when it returns to the start the pulse will be exactly the same duration as it was when it was emitted, again as measured by the slowed clocks. There is no change that can be detected by your experiment so it will give you a null result every time.

#### butchmurray

• Sr. Member
• 194
• If I had my druthers, I would have druthers
##### Re: Experiment to determine the one-way speed of light
« Reply #14 on: 24/01/2013 01:09:10 »
Hi David! I missed you.

There is only one clock. See Figure 5.

The experiment is stationary and all of its components are stationary in relationship to each other for the duration of the experiment.

The experiment can be performed in any orientation that permits sufficient distance to the reflector.

This experiment ascertains the one-way speed of light, something that has never been done. It is not the purpose of the experiment to prove anything. It acquires the necessary data and quantifies the speed of light in each of two opposite directions.

What horse are you referring to?

You interest is greatly appreciated.
Thank you,
Butch

I was not smart enough to know it was impossible to do what I did.

#### David Cooper

• Neilep Level Member
• 1505
##### Re: Experiment to determine the one-way speed of light
« Reply #15 on: 24/01/2013 20:25:55 »
Hi Butch,

Hi David! I missed you.

Well, where have you been? You've been away forever!

Quote
There is only one clock. See Figure 5.

That's fine as it makes no odds - you can time a second on it and use the same clock to judge whether the second it ticked out lasted a second.

Quote
The experiment is stationary and all of its components are stationary in relationship to each other for the duration of the experiment.

It's only stationary if it isn't moving, which it probably is.

Quote
This experiment ascertains the one-way speed of light, something that has never been done.

All it will do is assert that it's the same speed in both directions.

Quote
It is not the purpose of the experiment to prove anything.

That's lucky.

Quote
It acquires the necessary data and quantifies the speed of light in each of two opposite directions.

If it could do that, I'd be excited about it.

Quote
What horse are you referring to?