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Author Topic: Is the speed of light different in different directions?  (Read 4732 times)

David Cooper

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Is the speed of light different in different directions?
« on: 22/03/2015 02:30:46 »
When you look at something moving past you, if you decide that the speed of light passing you in different directions is the same, you will naturally decide that the speed of light going past that moving object must be different in different directions for that object. However, if you then move with that object, you'll find that you can't measure any difference in the speed of light in different directions across it at all, so you might assert that it's the same in all of them on the basis that you can't measure any difference (which would be bad reasoning, but no one would be able to prove you wrong, so you might well get away with it). Importantly though, there is a trick played with the time dimension for moving objects which adds a layer of complexity to things in relativity, thereby making it hard for people to see that the trick does not eliminate the issue, but merely ensures that it is burried in a sufficient depth of confusion that hardly anyone will be capable of understanding that the difference in speed across one or other of these objects in different directions must still be there. This complexity then makes room for people to claim that all frames of reference are valid and that there are no contradictions generated in relativity, even though there are. However, I've found an experiment that makes things a little bit clearer (thanks to http://www.conspiracyoflight.com/Hafele/HafeleKeating.html):-

Imagine a fibre-optic cable going right round the Earth at the equator. We can send light out through this cable from point X in opposite directions, and the light will go right round the world before returning to point X a moment later. Now, because the planet is rotating eastwards, the light that goes east through the cable will obviously take longer to return to point X than the light that goes westwards (and this difference can be measured in real experiments). At any point around the world we can look at the cable and say that the light is probably going faster through that point in a westward direction than eastward. For the speed of light to be the same in both directions at all points of the cable, the time taken for it to get round the whole loop would have to be identical for the complete trip from point X back to point X in both directions, but it isn't, so there must be some points in the cable where the speed of light through them is faster westwards than eastwards.

Now, it's possible to try to muddy the waters by pointing to the rotation of the Earth and claiming that this interferes with the experiment in some complex way, but we can get around that by considering simple tangents to this circle. The speed of light along each of these straight lines should be the same in both directions, according to Einstein's Relativity, and this neatly eliminates all the rotation at each point that we're considering. The circular path of the cable is effectively following one of these straight lines for a moment at any point along its path. There may be light travelling along these tangents alongside the cable, and that light cannot be allowed to be overtaken by the light in the cable, so the speed of light in the cable must match the speed of the light outside the cable (ignoring the very slightly slower speed of travel through the glass - we can redesign the experiment to eliminate the glass on most of the path, and if we rotate the Earth at a higher speed, we can easily reach a point where the any delay caused by the glass medium becomes irrelevant as we can have the light take twice as long to return to point X if it goes eastwards than if it goes westwards, or three times as long, or a thousand times, or any multiple we like).

If we are moving along the tangent that passes through point X, we can consider ourselves to be stationary, and for a moment point X will be stationary with us. At that point we can assert that light is travelling at the same speed in both directions along this tangent (and also through the fibre-optic cable at that point), and it may even be the same speed both ways, by chance. We would then have to regard the Earth as travelling past us and rotating, so points on the cable on the other side of the Earth will be moving relative to us and we will therefore regard the speed of light as being different in different directions through them as a result, though we would expect observers at those points to assert that the speed of light in different directions is the same where they are and to claim that it must be different where we are. This then is no different from any normal situation where you look at an object moving past you and think that the speed of light across it must be different in different directions. The difference is that if we try to play tricks with the time dimension, we can't hide the problem away and assert that this twist magically makes the speed of light the same in both directions across that moving object. In this example with the rotating Earth it is much easier to see that there is no trick that can be played with the time dimension which can eliminate the difference in the speed of light through all the points on our circuit. A twist into a time dimension can certainly make the passing of time different, but it cannot remove an asymmetry from the speed of light - the asymmetry merely remains hidden because it is undetectable, so it is possible to assert that it has gone away even though it hasn't.

If Einstein was to walk around the length of this fibre-optic cable, he would stop at each step and say, "Ze speed of light is ze same in boass directions relative to ziss point", but when pulses of light are simultaneously sent out from point X in both directions and fail to arrive back at point X at the same time as each other, what would he say then? Would anyone like to speak for him?
« Last Edit: 22/03/2015 02:41:37 by David Cooper »

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #1 on: 22/03/2015 10:36:27 »
David,
I'll read through this for interest, but leave comments to others as this is not my field. Just an 'off top of head' question, you say Imagine a fibre-optic cable going right round the Earth at the equator.. Why equator, why all the way round?
Could you set up an experiment at any latitude? What about a loop/circular cable east/west? As the earth rotates it would go both ways through space.
Just thinking that US is covered with network of cables and experiment might be possible east/west and north/south

Just an additional though, I haven't had time to think through. When earth is moving through space as in M&M experiment the earth is not dragging any 'medium' with it, same with the train thought experiments. In the case of a cable the medium is moving, wouldn't that be the equivalent of an aether making the experiment invalid?

« Last Edit: 22/03/2015 10:40:47 by Colin2B »

Thebox

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Re: Is the speed of light different in different directions?
« Reply #2 on: 22/03/2015 11:49:26 »
Thought I was a crackpot?

I can draw the diagram, I have the video,

Great post and well worded.

RD

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Re: Is the speed of light different in different directions?
« Reply #3 on: 22/03/2015 13:35:01 »
David Cooper is describing something resembling a fibre-optic "ring " interferometer ... http://en.wikipedia.org/wiki/File:Fibre-optic-interferometer.svg

Quote from: wikipedia.org/wiki/Sagnac_effect
...the sensitivity of the ring interferometer to rotation arises from the invariance of the speed of light for all inertial frames of reference.
http://en.wikipedia.org/wiki/Sagnac_effect
« Last Edit: 22/03/2015 13:44:54 by RD »

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #4 on: 22/03/2015 15:28:11 »
David Cooper is describing something resembling a fibre-optic "ring " interferometer ... http://en.wikipedia.org/wiki/File:Fibre-optic-interferometer.svg

Quote from: wikipedia.org/wiki/Sagnac_effect
...the sensitivity of the ring interferometer to rotation arises from the invariance of the speed of light for all inertial frames of reference.
http://en.wikipedia.org/wiki/Sagnac_effect

Thanks RD your link has answered 2 of my questions - any latitude will do, the loop would work and has in fact already been done 1.9km is quite impressive. If it can be done at any latitude, I assume it could be done at one of the rotational poles and need not remain a thought experiment, is that correct?.

My off the cuff thoughts failed to think about the effect within the moving medium. However, I would have thought that the difference in time to travel around the loop is due to length contraction of the path length as seen by the photons, not a change of light speed. That would be my first thought and I would need to go through in detail; but as I say, it's not my field so I'll await comments from the experts.

Had heard of optical gyroscope but put it on back burner for follow up, interesting description of effects I hadn't seen before, thanks
« Last Edit: 22/03/2015 16:59:23 by Colin2B »

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #5 on: 22/03/2015 19:26:21 »
quote author=RD
.the sensitivity of the ring interferometer to rotation arises from the invariance of the speed of light for all inertial frames of reference.
http://en.wikipedia.org/wiki/Sagnac_effect

Thanks again RD. Really interesting. I hadn't appreciated how the Fizeau experiments helped shape Einstein's views on relativity. When taken with the other evidence we can see how he reached his conclusions. The Sagnac effect is particularly interesting as a relativistic result.

quote author=David Cooper
If Einstein was to walk around the length of this fibre-optic cable, he would stop at each step and say, "Ze speed of light is ze same in boass directions relative to ziss point", but when pulses of light are simultaneously sent out from point X in both directions and fail to arrive back at point X at the same time as each other, what would he say then? Would anyone like to speak for him?

David, thanks for this thought experiment.
The error of thinking obviously lies in the 2nd paragraph. I like the way you have constructed this - particularly the sleight of hand distraction talking about walking round the circuit, nice touch that.
What would Einstein say next? Probably, "well that's pretty obvious, fully predicted by relativity, why would anyone think there is a problem?"
« Last Edit: 22/03/2015 20:48:09 by Colin2B »

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #6 on: 22/03/2015 21:12:17 »
David,
I'll read through this for interest, but leave comments to others as this is not my field. Just an 'off top of head' question, you say Imagine a fibre-optic cable going right round the Earth at the equator.. Why equator, why all the way round?

It's just easiest to visualise it at the equator. It has to go all the way round or you won't get any results out of it.

Quote
Just an additional though, I haven't had time to think through. When earth is moving through space as in M&M experiment the earth is not dragging any 'medium' with it, same with the train thought experiments. In the case of a cable the medium is moving, wouldn't that be the equivalent of an aether making the experiment invalid?

I made a point of saying that you can eliminate most of the cable, but I also pointed out that the light in the cable cannot go faster than the light outside the cable, so there cannot be any dragging advantage by moving the medium.

_________________________________________________________

Thought I was a crackpot?

Everyone can be a crackpot to those on the other side whenever there are incompatible beliefs involved. Some of the crackpots are right though and some are wrong, so the difficulty is in working out which side is right. What I'm trying to do here is help people question their beliefs and check to see if they're really sure of the ground they're standing on.

_________________________________________________________

My off the cuff thoughts failed to think about the effect within the moving medium. However, I would have thought that the difference in time to travel around the loop is due to length contraction of the path length as seen by the photons, not a change of light speed.

If you want to contract the length from the point of view of photons, all paths they travel are of zero length.

David, thanks for this thought experiment.
The error of thinking obviously lies in the 2nd paragraph. I like the way you have constructed this - particularly the sleight of hand distraction talking about walking round the circuit, nice touch that.

There's no error or trickery involved in it - you've just missed the point I'm making.

Quote
What would Einstein say next? Probably, "well that's pretty obvious, fully predicted by relativity, why would anyone think there is a problem?"

That's probably not far wrong - he always was completely blind to the problem. If the speed of light is really the same in both directions at each point on the circuit relative to each point on the circuit, both pulses of light should arrive back at X simultaneously. They don't, so the speed of light cannot be the same in both directions at some of those points relative to those points. This is not an attack on relativity, but on a pointless piece of unjustifiable dogma which Einstein insisted on attaching to it when he rejected the idea of a preferred frame. A preferred frame does not destroy relativity, but simply removes some irrationality from it. If the speed of light across point X is the same relative to point X in both directions, it cannot be the same relative to point Y (on the opposite side of the planet) in both directions. You can then then switch frame and look at point Y and assert that the speed of light is the same relative to that point in both directions, but now to be consistent with this new claim you have to accept that the speed of light is no longer the same in both directions relative to point X. Einstein's walk around the planet is a journey of inconsistency in which he keeps switching frame of reference. He wants to have his cake and eat it - he wants all frames of reference to be true at the same time instead of accepting that if one of them is correct, some of the others are necessarily wrong. What he does would be equivalent to Lorentz pushing his aether theory and asserting that it doesn't need a preferred frame either - all frames of reference could then be considered to be true even though the accounts they give of events contradict each other. It is this toleration of contradiction that I object to, and I have never understood how so many intelligent people can hold such contradictions in their heads without it setting off alarm bells. The claim that the speed of light is the same in all directions is based on no evidence and leads to an infinite number of contradictions. I don't know how anyone can stomach it. It is also a completely unnecessary claim which adds nothing useful to the theory.
« Last Edit: 22/03/2015 21:15:06 by David Cooper »

Thebox

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Re: Is the speed of light different in different directions?
« Reply #7 on: 22/03/2015 21:19:28 »
David,
I'll read through this for interest, but leave comments to others as this is not my field. Just an 'off top of head' question, you say Imagine a fibre-optic cable going right round the Earth at the equator.. Why equator, why all the way round?

It's just easiest to visualise it at the equator. It has to go all the way round or you won't get any results out of it.

Quote
Just an additional though, I haven't had time to think through. When earth is moving through space as in M&M experiment the earth is not dragging any 'medium' with it, same with the train thought experiments. In the case of a cable the medium is moving, wouldn't that be the equivalent of an aether making the experiment invalid?

I made a point of saying that you can eliminate most of the cable, but I also pointed out that the light in the cable cannot go faster than the light outside the cable, so there cannot be any dragging advantage by moving the medium.

_________________________________________________________

Thought I was a crackpot?

Everyone can be a crackpot to those on the other side whenever there are incompatible beliefs involved. Some of the crackpots are right though and some are wrong, so the difficulty is in working out which side is right. What I'm trying to do here is help people question their beliefs and check to see if they're really sure of the ground they're standing on.

_________________________________________________________

My off the cuff thoughts failed to think about the effect within the moving medium. However, I would have thought that the difference in time to travel around the loop is due to length contraction of the path length as seen by the photons, not a change of light speed.

If you want to contract the length from the point of view of photons, all paths they travel are of zero length.

David, thanks for this thought experiment.
The error of thinking obviously lies in the 2nd paragraph. I like the way you have constructed this - particularly the sleight of hand distraction talking about walking round the circuit, nice touch that.

There's no error or trickery involved in it - you've just missed the point I'm making.

Quote
What would Einstein say next? Probably, "well that's pretty obvious, fully predicted by relativity, why would anyone think there is a problem?"

That's probably not far wrong - he always was completely blind to the problem. If the speed of light is really the same in both directions at each point on the circuit relative to each point on the circuit, both pulses of light should arrive back at X simultaneously. They don't, so the speed of light cannot be the same in both directions at some of those points relative to those points. This is not an attack on relativity, but on a pointless piece of unjustifiable dogma which Einstein insisted on attaching to it when he rejected the idea of a preferred frame. A preferred frame does not destroy relativity, but simply removes some irrationality from it. If the speed of light across point X is the same relative to point X in both directions, it cannot be the same relative to point Y (on the opposite side of the planet) in both directions. You can then then switch frame and look at point Y and assert that the speed of light is the same relative to that point in both directions, but now to be consistent with this new claim you have to accept that the speed of light is no longer the same in both directions relative to point X. Einstein's walk around the planet is a journey of inconsistency in which he keeps switching frame of reference. He wants to have his cake and eat it - he wants all frames of reference to be true at the same time instead of accepting that if one of them is correct, some of the others are necessarily wrong. What he does would be equivalent to Lorentz pushing his aether theory and asserting that it doesn't need a preferred frame either - all frames of reference could then be considered to be true even though the accounts they give of events contradict each other. It is this toleration of contradiction that I object to, and I have never understood how so many intelligent people can hold such contradictions in their heads without it setting off alarm bells. The claim that the speed of light is the same in all directions is based on no evidence and which leads to an infinite number of contradictions. I don't know how anyone can stomach it.

David I do not wish to butt in your conversation I just wanted to point something out to you,

Consider while you are observing anything, the light from what ever you are observing travels towards your eyes at a linearity and constant speed always otherwise you would not see what you were observing.
Place a sweeping brush stale end by your eye, and move the brush end around in a circle.

Think bigger David, Imagine all of space is inside of a fibre optic cable and we are within the light always.

Ze cable would not be ze same as ze transparent constant, ze interference would be man made by observer effect.  Ze constant in space is the same in all directions to all observers unless  by interference.
« Last Edit: 22/03/2015 21:37:28 by Thebox »

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #8 on: 22/03/2015 22:53:45 »

I made a point of saying that you can eliminate most of the cable, but I also pointed out that the light in the cable cannot go faster than the light outside the cable, so there cannot be any dragging advantage by moving the medium.

If you want to contract the length from the point of view of photons, all paths they travel are of zero length.

There's no error or trickery involved in it - you've just missed the point I'm making.

David
By the time of my last post I had rejected dragging & contraction, but I was preparing supper and trying to do various other multitaskings.
I'll re read your post again in light of your comments, as I say not my area so interested to learn what is happening here.
Thanks again

Edit: looking at my work plan, I've got a lot to fit in over the next month and I would want to add some other background reading. I'm aware of the LET/relativity duality in some areas so would want to include some of that as well. All in all will take me a few weeks to work that around everything else and do justice to the topic, but could be worth it for an interesting discussion.
« Last Edit: 23/03/2015 00:06:58 by Colin2B »

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #9 on: 23/03/2015 01:25:42 »
David
By the time of my last post I had rejected dragging & contraction, but I was preparing supper and trying to do various other multitaskings.
I'll re read your post again in light of your comments, as I say not my area so interested to learn what is happening here.
Thanks again

Edit: looking at my work plan, I've got a lot to fit in over the next month and I would want to add some other background reading. I'm aware of the LET/relativity duality in some areas so would want to include some of that as well. All in all will take me a few weeks to work that around everything else and do justice to the topic, but could be worth it for an interesting discussion.

It's not a race, so by all means take time to read up on things first as the time becomes available. When I started reading up on relativity I thought it must be based on arguments which actually disproved the older idea of aether. The idea of aether being dragged around was certainly killed off - Lorentz took a wrong turn there when he tried that out as an answer to Michelson Morley, but he then took a better direction and came up with an aether theory (which would be better described as a fabric-of-space theory) which does still stands up to experiment. The impression given by mainstream science is that LET was killed off by experiments, but that is not the case at all. It also gives the impression that Einstein's relativity is logically superior, but again that is not is the case. The result is that people in the mainstream make unjustifiable assertions about the nature of reality and they are not being held to account for this. The reality is that Einstein's relativity and Lorentz's LET are both viable interpretations of the facts when it comes to fitting in with the results of experiments, they are mathematically identical, and both should be counted as mainstream. I think lorentz has been very badly treated in all of this and his theory deserves to be given an equal billing in mainstream physics. (I personally regard LET as logically superior, but that's another issue - I simply hope that other people will recognise that it is still a player and not an extinct relic which can be dismissed.)

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #10 on: 23/03/2015 01:39:07 »
David I do not wish to butt in your conversation I just wanted to point something out to you,

Consider while you are observing anything, the light from what ever you are observing travels towards your eyes at a linearity and constant speed always otherwise you would not see what you were observing.
Place a sweeping brush stale end by your eye, and move the brush end around in a circle.

That sounds like a dangerous experiment, but and a very unrewarding one too as it will not settle anything relating to the speed of light in a single direction (and probably won't settle anything relating to the speed of light at all).

Quote
Think bigger David, Imagine all of space is inside of a fibre optic cable and we are within the light always.

Do you mean like a fabric of space with light travelling through it? That's an interesting new idea to explore.

Quote
Ze cable would not be ze same as ze transparent constant, ze interference would be man made by observer effect.  Ze constant in space is the same in all directions to all observers unless  by interference.

Ze cable in my sought experiment can be removed - it vurks wiss ze fabric of space alone (so long as it can be helped round a few corners in order to follow a circuit). Ze space fabric is ze sing zat enforces a speed limit on light in such a vay zat no photon can overtake any uzzer photon.

Thebox

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Re: Is the speed of light different in different directions?
« Reply #11 on: 23/03/2015 10:22:57 »
David I do not wish to butt in your conversation I just wanted to point something out to you,

Consider while you are observing anything, the light from what ever you are observing travels towards your eyes at a linearity and constant speed always otherwise you would not see what you were observing.
Place a sweeping brush stale end by your eye, and move the brush end around in a circle.

That sounds like a dangerous experiment, but and a very unrewarding one too as it will not settle anything relating to the speed of light in a single direction (and probably won't settle anything relating to the speed of light at all).

Quote
Think bigger David, Imagine all of space is inside of a fibre optic cable and we are within the light always.

Do you mean like a fabric of space with light travelling through it? That's an interesting new idea to explore.

Quote
Ze cable would not be ze same as ze transparent constant, ze interference would be man made by observer effect.  Ze constant in space is the same in all directions to all observers unless  by interference.

Ze cable in my sought experiment can be removed - it vurks wiss ze fabric of space alone (so long as it can be helped round a few corners in order to follow a circuit). Ze space fabric is ze sing zat enforces a speed limit on light in such a vay zat no photon can overtake any uzzer photon.

Ze satellites transmit light through ze constant light, my sought's are without ze interference of external forces such as ze interference by man, helping light around ze corners is interference and not ze natural of ze constant, ze sought's and ze experiments with ze light have no effect on ze constant of light travelling through space.
Ze Photon can overtake another Photon if ze other photon is obstructed by ze medium and ze refractive  index of a cloud for example, relative to ze un-obstructed photon that passes ze cloud by .
I see ze energy of the Universe,

E=4/3πr3*P

« Last Edit: 23/03/2015 12:28:29 by Thebox »

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #12 on: 23/03/2015 17:33:15 »
Please avoid quoting people's entire posts in a huge block every time you reply - if you hack the content of it down to the little bit you want to comment on you'll find that you irritate people less, and bit by bit they may warm to you as they see improvement. If there are multiple bits you'd like to comment on separately, you can type [ /quote ] at the end of the first chunk and then put [ quote ] and [ /quote ] around the rest (but without the spaces between the square brackets and their content). Then click on "preview" instead of "post" to make sure you've done it correctly.

helping light around ze corners is interference

All that matters is the comparison between the speed of light doing the circuit and light going past in a straight line at a point when the light doing the circuit is going in the same direction and is not inside glass. It actually doesn't matter if it is still in the glass though, because no amount of movement of the glass can increase the speed of light inside it to the point where it can overtake light outside the glass. That the light inside the glass can be slower than light outside the glass is not a problem for the experiment.

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #13 on: 24/03/2015 17:42:26 »
David

I promised to look again at this problem and I have been mulling it over as I go through the day's activities. However, I still have a problem with para 2.

In my response I tried to be covert so as to leave other to come to their own conclusions, but to explain I will have to be specific.
Having read the link from RD there seemed to be a direct analogy between the optical gyroscope and what you describe so my problem with para 2 lay in the statement

"For the speed of light to be the same in both directions at all points of the cable, the time taken for it to get round the whole loop would have to be identical for the complete trip from point X back to point X in both directions,"

It appears we have to use rotational distance , phase velocities and relativitistic velocity addition to determine the speed of the light for each direction in the cable.  What is interesting is that this still works if the ring is stationary and the source/sensor is moving. Neither is it frame dependant!

However, I accept that this may be due to my misunderstanding or preconceived ideas so I'm definitely going to keep following this one up, so this is on the reading and study list.
Do you have a different explanation of this from the LET viewpoint?

Re the 2nd part. Para 3&4
Although this is related to the set up in part 1, I don't see them as dependant. I see it as an independent problem.
I don't have a problem with gravitation influence as we could move this into space and it still work.
I know there can be interesting effects with light in a medium eg electrons going faster than light in the medium, but I don't think anything like that is relevant. We both agree that there is no local 'aether effect' due to the moving medium. (other than the Sagnac and Fizeau effects which we have accounted for in the 1st part)
I do have a problem with ignoring the difference in speed between glass and space, but we could consider a hypothetical medium of RI=1, so that would be ok.
I have a problem with walks arounds as they can mislead us into changing FofR without realising it.

I was trying to think of a different way of visualising this. I thought of a playground roundabout with children on the roundabout holding torches shining in the direction of travel. This takes away the problem of considering the light in the cable to be the same as that outside the cable, and as nothing can travel faster than light, the light from the torches is equivalent to the light travelling around a loop.
There are a number of ways we can observe this roundabout. We can stand still watching, we can sit on the roundabout, or we can run alongside at the same velocity (tangentially). For this last one we can, as you say, consider ourselves stationary with respect to the roundabout. The way I visualise this is that we would now be the pivot point for a new circle with a radius replacing the roundabout's diameter. If we construct our FofR with us as the origin, one axis through the radius and the other perpendicular to that from our location we can consider the motion of the points around the roundabout.

Each one will have a velocity relative to our frame which we can treat (instantaneously as in your experiment) as if they are inertial. Obviously there will be some relativistic effects as we consider each point, but instantaneously we should be able to work out what is happening. (Better strap the children on tight  )

As I've been writing this I've realised that each of the points around the roundabout, although they can consider themselves stationary relatives to a FofR, those frames will not be inertial because the frames and the points will be accelerating. What do you think?

My knowledge of SR is limited so GR is a whole new ball game. This one could take a lot longer than I thought. However, it is going to be both interesting and challenging. Hopefully someone with more knowledge in this area will be able to step in and help. I say more knowledge because I'm sure there are many crackpots who would like to confuse the issue.

PS you mention crackpots in one of your posts. Despite the tag under your name, I don't consider you a crackpot. You have a firm understanding of physics, logic and scientific method and you are rightly questioning and challenging, but retaining the scientific method and basing those questions on the rock of understanding. Like you I see areas where LET and relativity produce similar results, i also don't view Einstein as infallible so am happy to see assumptions challenged. I hope to be able to understand the issues, but accept it might be beyond my constraints of time and understanding.
But interesting nevertheless.

I have to be off now, wood to prepare and calculations to be done for my next project.

Edit: sorry long post, but then it's a big subject!
Speak soon
« Last Edit: 24/03/2015 18:41:25 by Colin2B »

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #14 on: 24/03/2015 20:57:58 »
Having read the link from RD there seemed to be a direct analogy between the optical gyroscope and what you describe so my problem with para 2 lay in the statement

"For the speed of light to be the same in both directions at all points of the cable, the time taken for it to get round the whole loop would have to be identical for the complete trip from point X back to point X in both directions,"

It's difficult to phrase everything perfectly, and it's easy to interpret the above in more than one way because the wording wasn't tight enough there. Clearly the speed of light can be the same in all directions at every point in the ring when it's analysed from the perspective of a single frame of reference, but it cannot be the same in all directions at each point relative to that point all round the ring if the time taken for the light to get round the whole loop from X to X in both directions isn't identical. It can only be asserted as being the same speed in both directions at any given point by using that point as an anchor for a frame of reference. If all frames of reference can be taken as being correct though, you should be able to pick and choose: you should be able to say that every single point has the speed of light going through it the same in both directions and thus determine that light will take the same length of time to go from X to X in both directions while also not taking the same time. The contradiction in this final conclusion is no worse than the contradictions which were previously being hidden by studiously ignoring them and pretending they aren't there.

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Do you have a different explanation of this from the LET viewpoint?

There is very little difference between the SR and LET analysis of this. In each case you analyse things from the point of view of a single frame of reference and everything works out fine. If you switch to a different frame and repeat the analysis it works out fine again, and it will work out fine for every frame you want to use. The difference is in the logic. Lorentz looks at things and determines that if the accounts of events from the perspective of one frame are correct, the accounts of events from the perspective of other frames which contradict it would necessarily require those accounts to be false - there must be a preferred frame of reference which generates true accounts while the other frames generate false accounts, though it's impossible to determine which frame is the preferred one. Einstein looks at the same thing and denies that there is a preferred frame on the basis that it's impossible to pin down which one it is, so he asserts that all the frames are equally valid, implying that all of the accounts generated from them are true and that none are false. That is where he introduces an infinite number of wholly unnecessary contradictions into his theory, just by attaching this little piece of irrational dogma to it.

There is a more important difference between SR and LET which relates to the nature of time, so it would be possible to have four theories here rather than two: an irrational version of LET could assert that all frames are valid and that there is no preferred frame, thereby introducing an infinite number of contradictions into it, and a more rational version of SR could assert that SR has the equivalent of a preferred frame which generates true accounts while all the others which contradict it are generating false accounts - that would fix this problem for SR and GR and would take absolutely none of their functionality away from them, so it is extraordinary that mainstream science insists on retaining Einstein's dogma when it is so horribly illogical.

I have discussed the problem with the dogma in a different way here: http://www.newenglandphysics.org/amateur_forum/viewtopic.php?f=27&t=65 - after the first couple of posts, it switches into a comparison between the proposed mechanisms behind time dilation in LET and SR and shows why SR logically requires a direct equivalent of a preferred frame. (Old threads burried in the depths of this forum [TNS] also cover this ground, but the argument is more clearly stated in the new thread.)

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I do have a problem with ignoring the difference in speed between glass and space, but we could consider a hypothetical medium of RI=1, so that would be ok.

The cable is only there to steer the light round a circuit. We could replace it with a reflective ring to serve as an infinite number of mirrors, thereby allowing the light to be reflected all the way round regardless of any rotation speed. 99.99999...% of the time the light would be passing through nothing but open space (if we eliminate the Earth's atmosphere, which we can easily do by placing the entire ring in deep space away from a planet entirely). Any error in timings caused by delays during reflections are insignificant once we start rotating the experiment (and the same applies to any delays from using a glass medium to contain the light, which is why this has never been a problem for the experiment in any case).

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I have a problem with walks arounds as they can mislead us into changing FofR without realising it.

The whole point of the thought experiment is to draw attention to this changing of frames of reference, so it isn't being hidden away to trick anyone.

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The way I visualise this is that we would now be the pivot point for a new circle with a radius replacing the roundabout's diameter. If we construct our FofR with us as the origin, one axis through the radius and the other perpendicular to that from our location we can consider the motion of the points around the roundabout.

There isn't any need to redesign the experiment - it is sufficient just to set out why the factors which might introduce errors can be ignored and then to ignore them - none of the errors will be significant given the huge discrepency in timings of the light arriving back at point X from different sides when the experiment is rotated fast. This means we can just assume that the speed of light in glass is the same as outside of glass and that there is no slowing during reflections - clearly there will actually be slowings from both of these things, but they will be infinitesimal compared with the huge differences we're looking at at point X due to the rotation of the experiment, and we only need a tiny difference there to illustrate the point that there is a difference there caused by rotation of the experiment.

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As I've been writing this I've realised that each of the points around the roundabout, although they can consider themselves stationary relatives to a FofR, those frames will not be inertial because the frames and the points will be accelerating. What do you think?

That's why I introduced the tangents - each point is for a moment stationary within the frame of reference of a point on a tangent to the circle, and whatever can be said about the speed of light along that tangent in each direction will at that moment apply equally to the point on the circle that you are considering.

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My knowledge of SR is limited so GR is a whole new ball game. This one could take a lot longer than I thought.

We don't need to consider GR here at all.

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PS you mention crackpots in one of your posts. Despite the tag under your name, I don't consider you a crackpot.

I put that tag there out of solidarity for crackpots because I like a lot of crackpots - science is full of them and they are something to celebrate. I would put Einstein on my own crackpot list because he has built something wholly unnecessary and quite bonkers into his theory which introduces an infinite number of contradictions into it. What I find extraordinary is that so few people are prepared to stand up and say that they too reject that piece of dogma - I can only think that either they're incapable of seeing the contradictions, or maybe they fear that by speaking out they will label themselves as crackpots in the eyes of the hordes of unthinking followers of the mainstream who have been systematically trained to stuff their heads with required beliefs without ever stopping to question them.

Here we have a thought experiment which makes it easier to see the contradictions. If the accounts of events from all frames of reference are equally true, we can pick and choose any parts of any account from any frames of reference and stick them all together to make a composite account which might state that the light must go from X to X in both directions in the same time, and we can pick and choose any parts of any accounts from any frames of reference and stick them all together to make a rival composite account which might state that the light must take different lengths of time to go from X to X in different directions. The result of that is a clear contradiction in the preciction, and one of them will not agree with the result of an actual experiment. That one of these composite accounts fails to fit with the facts proves that some of the claims within it are not true, and yet they all supposedly come from accounts which are entirely true. The reality is that most of the accounts are not true and that the analysis from some frames of reference are truer than others, even though we cannot tell which they are.
« Last Edit: 24/03/2015 21:00:12 by David Cooper »

PmbPhy

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Re: Is the speed of light different in different directions?
« Reply #15 on: 26/03/2015 17:46:26 »

Let me elaborate with an example of what I'm talking about. You start off with this:
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When you look at something moving past you, if you decide that the speed of light passing you in different directions is the same, you will naturally decide that the speed of light going past that moving object must be different in different directions for that object.
I don't understand what this is saying. What do you mean by you will naturally decide that the speed of light going past that moving object must be different in different directions for that object.

Can you please explain what this means and why I should naturally decide that, please?  Do you mean the relative speed?

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #16 on: 26/03/2015 18:40:47 »

Let me elaborate with an example of what I'm talking about. You start off with this:
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When you look at something moving past you, if you decide that the speed of light passing you in different directions is the same, you will naturally decide that the speed of light going past that moving object must be different in different directions for that object.
I don't understand what this is saying. What do you mean by you will naturally decide that the speed of light going past that moving object must be different in different directions for that object.

Can you please explain what this means and why I should naturally decide that, please?  Do you mean the relative speed?
David, I was preparing this post but, PmbPhy has said something similar:

I understand what you are saying but my comments were really aimed at the example you give. I don't feel it gives your assertions the support they need.
Many people will look at the fibre loop and conclude that the way it works does not support the example of light in the cable being same speed as that outside, or the same in both directions. They will then dismiss all the rest of your post despite the illogic of them doing so!
You would be better to use the mirrors example that you describe, because the speed of light is the already the same inside and outside the circuit.

I am convinced that this is not an effect of differing light speeds, but I need to try out some ideas first.
Spk later

PmbPhy

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Re: Is the speed of light different in different directions?
« Reply #17 on: 26/03/2015 19:07:53 »
Quote from: Colin2B
David, I was preparing this post but, PmbPhy has said something similar:

I understand what you are saying but my comments were really aimed at the example you give. I don't feel it gives your assertions the support they need. ....
Colin, my friend! I'm confused. First you quote me and then you address David? Is that correct? If so can you please answer the question I asked you in case you forgot? Thanks.

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #18 on: 26/03/2015 21:12:13 »
David - I've wanted for some time now to mention something to you about the threads you start. First off it appears from what little I read of them that they're well thought out. I'd love to be able to read the whole thing. However, like this thread, I find them very hard to understand. I also hate to read a post that is as long as the one you started this thread with.

There are two difficulties there - an argument cannot be made shorter than the number of words needed to express it, and the tighter you try to make the wording, the longer it gets. It's always a compromise between removing ambiguity and keeping it short.

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Could you rewrite the opening thread in a clearer and simpler way and maybe even much shorter?

I don't think it would be possible to make it shorter and clearer at the same time. I could do a shorter version that would be harder to follow, or a clearer version that's much longer. The best way forward would be for you to question the bits you aren't sure about, as you have done with the following:-

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Let me elaborate with an example of what I'm talking about. You start off with this:
Quote
When you look at something moving past you, if you decide that the speed of light passing you in different directions is the same, you will naturally decide that the speed of light going past that moving object must be different in different directions for that object.
I don't understand what this is saying. What do you mean by you will naturally decide that the speed of light going past that moving object must be different in different directions for that object.

Can you please explain what this means and why I should naturally decide that, please?  Do you mean the relative speed?

Yes, I mean the relative speed. If you are watching something go past you at 50% the speed of light (and if you assume that you aren't moving), you will naturally think that the speed of light relative to that object (when viewed from your perspective) must be 150% the speed of light in one direction and only 50% in the other (and a variety of other speeds between those two extremes at other angles in between). If you want to work out the time dilation for that moving object you would most naturally treat it as if it is moving while you are stationary, and you will then have to assume that light moves at c relative to you at all times. That automatically means that you can't treat light as if it is moving at c in all directions relative to anything that is moving relative to you.

(That illustrates how attempting to eliminate ambiguity makes explanations longer, and it may now need to be further lengthened to clear up any new ambiguities.)

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #19 on: 26/03/2015 21:41:08 »
I understand what you are saying but my comments were really aimed at the example you give. I don't feel it gives your assertions the support they need.

If you've managed to follow the argument, perhaps you could help me to find a clearer way to state things that would be easier for people to follow. This is my first attempt at discussing this particular experiment and there may well be a better way of doing it. I have long found that most people appear to be unable to see the presense of contradictions even where they are manifestly there. I don't understand why they can't see them, but it keeps happening, so I'm always looking for new ways to make the contradictions show up more clearly, and this experiment looks as if it may help.

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Many people will look at the fibre loop and conclude that the way it works does not support the example of light in the cable being same speed as that outside, or the same in both directions. They will then dismiss all the rest of your post despite the illogic of them doing so!

That may be so, but the argument is aimed at people at the higher end of knowledge and thinking ability - it's hard enough even to get it into a form that they can follow, so it may be an impossible task to put it across to the masses.

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You would be better to use the mirrors example that you describe, because the speed of light is the already the same inside and outside the circuit.

The trouble with mirrors is that as soon as you start rotating the experiment, the light beams start missing the mirrors. The fibre-optic cable eliminates that problem and enables speed of travel for light which is sufficiently close to c that it can be treated as if it is c. If anyone wants to attack my conclusions based on some aspect of slowing or speeding up of light by moving the glass medium, I can then show them why they're barking up the wrong tree by stripping away the glass and showing that it makes no difference. The reader should therefore just treat the experiment as if the speed of light is not affected by the glass.

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I am convinced that this is not an effect of differing light speeds, but I need to try out some ideas first.

Anyone who is worried about the glass can simply remove it and insert an alternative mechanism for steering it round the ring. Importantly though, at any point where we stand and look at the cable, the glass is not moving relative to us at that point, so if we decide that the speed of light where we are standing is the same relative to us in all directions, it may be slightly slower in the glass of the cable, but it will still be the same in both directions within the cable, and the same will apply at any point of the cable that we go and look at. We could also cut a short section out of the cable at any point and fix a couple of conical mirrors onto the ends to shoot the light across the gap without the glass slowing it, at which point it would be exactly as fast as the light outside the cable. If we get rid of the atmosphere we can speed it up further. None of these modifications change any of the important aspects of the experiment or the conclusion that I have drawn from it.
« Last Edit: 26/03/2015 21:43:27 by David Cooper »

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #20 on: 26/03/2015 22:30:09 »
Colin, my friend! I'm confused. First you quote me and then you address David? Is that correct? If so can you please answer the question I asked you in case you forgot? Thanks.

Sorry, my malfunctioning, male multitasking strikes again.
Brain not catching up with fingers, ignore me

Colin2B

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Re: Is the speed of light different in different directions?
« Reply #21 on: 26/03/2015 23:01:32 »
If you've managed to follow the argument, perhaps you could help me to find a clearer way to state things that would be easier for people to follow.

Working on that. Since that post I've thought of a way of looking at it which solves the mirror issue. I'm using it to look at Sagnac effect. Happy if you use it. Will share in private 1st rather than clutter your thread.

yor_on

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Re: Is the speed of light different in different directions?
« Reply #22 on: 25/04/2015 19:19:16 »
Huh?

"Now, because the planet is rotating eastwards, the light that goes east through the cable will obviously take longer to return to point X than the light that goes westwards (and this difference can be measured in real experiments)"

:) Naah, don't think so. Let's see, what do we have experimentally? http://www.nobelprize.org/educational/physics/relativity/experiment-1.html ?

So what you define here is what I would call 'absolute motion', but :) relative what? Where is the gold standard? What we can define experimentally is a red, respectively, blue shift. We call that a equivalence to accelerations.

David Cooper

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Re: Is the speed of light different in different directions?
« Reply #23 on: 25/04/2015 20:23:10 »
Huh?

Huh?

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"Now, because the planet is rotating eastwards, the light that goes east through the cable will obviously take longer to return to point X than the light that goes westwards (and this difference can be measured in real experiments)"

:) Naah, don't think so. Let's see, what do we have experimentally? http://www.nobelprize.org/educational/physics/relativity/experiment-1.html ?

You've linked to an irrelevant experiment. If you send light right round the world in a fibre optic cable in both eastward and westward directions, the light travelling westwards will return to the emmitter/detector first.

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So what you define here is what I would call 'absolute motion', but :) relative what? Where is the gold standard? What we can define experimentally is a red, respectively, blue shift. We call that a equivalence to accelerations.

No red or blue shift is detected in this experiment, but we have a particular set of happenings which dictates that at some of the locations on the way round the circuit the speed of light cannot be the same in both directions. I would suggest that this requires there to be an absolute frame.

Spring Theory

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Re: Is the speed of light different in different directions?
« Reply #24 on: 14/05/2015 21:46:56 »
The only way you could accurately interpret the Hafele and Keating time dilation experiment is if you knew the true rest frame of motion. Since the earth's rotation, orbit, sun's orbit, galaxy's orbit, clusters orbit...etc would have to be taken into account, it is difficult to judge.

Two planes in the opposite direction around the earth are actually opposite "rotations" and could conceivably be in very different relative frame velocities. Say for example one directional path was rotating in the same direction as the absolute rest frame of motion, then the other would be rotating opposite relative to that frame of motion. One plane would have a higher average absolute velocity than the other.

The faster relative moving reference frame would appear have a slower clock than the one moving closer to the at rest frame due to perceived time dilation.

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Re: Is the speed of light different in different directions?
« Reply #24 on: 14/05/2015 21:46:56 »