[xersanozgen (OP)]

Is the M-M experiment futile?

Michelson-Morley interferometer experiment had been repeated thousands of times by more/most precision; but the amount of interference fringes did not change for different directions.

In accordance with aether concept, we would hope different interference images for different directions.

In the texts about this experiment it is mentioned that the light is separated two parts, they travel different paths due to mirrors and they interference on a surface. I had supposed that these two lights are the halves of a light how it is released at the moment Ti. I guess that so much person have same opinion; whereas it cannot be guaranteed.

If we examine the figure at attachment we will see that the light comes to an observer/receiver by always the velocity c absolutely, although the speeds of source and observer. So, the light halves are belonging to two different lights which releases at different moments (the light is used uninterrupted form).

If we set a similar interference experiment with two light which one of them comes from a distant star and the other comes from a local source, the interference fringes image does not change. 

Is the M-M experiment futile?

[jeffreyH]

No. Why? Because it settled a debate and was crucial in freeing scientists of the burden of an ether. This led to developments in relativity that could not be argued away.

[evan_au]

If we set a similar interference experiment with two light which one of them comes from a distant star and the other comes from a local source

To measure the interference fringes very accurately, the light should come from a single-wavelength "coherent" light source (eg a laser).
Light from a distant star has multiple wavelengths, and will not be coherent with a local laser.
Light from distant stars is too faint to easily detect the interference fringes. 

[xersanozgen (OP)]

No. Why? Because it settled a debate and was crucial in freeing scientists of the burden of an ether.  This led to developments in relativity that could not be argued away.

 Yes, the ether paradigm had been collapsed and new theories are formed: well-known one of them (SR) and recently "LCS concept" by me ( https://www.thenakedscientists.com/forum/index.php?topic=70567.0 )

The reason of insistent repeatings was to eliminate the systematic and humanly errors for the beginning intention of the experiment. Whereas if we interference two different originated lights (without mirrored device), the result would be the same.

[xersanozgen (OP)]

If we set a similar interference experiment with two light which one of them comes from a distant star and the other comes from a local source

To measure the interference fringes very accurately, the light should come from a single-wavelength "coherent" light source (eg a laser).
Light from a distant star has multiple wavelengths, and will not be coherent with a local laser.
Light from distant stars is too faint to easily detect the interference fringes. 

 We can use/consider two different local sources  (their distances to the screen are not equal) or nearby sky objects to eliminate practical problems.

In my opinion the same result will be realized.

[David Cooper]

No. Why? Because it settled a debate and was crucial in freeing scientists of the burden of an ether. This led to developments in relativity that could not be argued away.

It didn't disprove the ether, and ether is hardly a burden either (but more of a provider of essential services, such as enabling there to be such a thing as a separation distance between two things) - all it did was show that an old assumption was wrong because length-contraction had not been predicted in advance of MM. In doing that though, it certainly showed that it wasn't futile, and its null result ties in with exactly what should happen with an ether.

[dutch]

It didn't disprove the ether, and ether is hardly a burden either (but more of a provider of essential services, such as enabling there to be such a thing as a separation distance between two things) - all it did was show that an old assumption was wrong because length-contraction had not been predicted in advance of MM. In doing that though, it certainly showed that it wasn't futile, and its null result ties in with exactly what should happen with an ether.

No, it didn't disprove the ether as the Lorentz Transform was developed for Lorentz' Ether Theory. Special Relativity and LET use the same math (with Lorentz' last version) and come to the same experimental conclusions. The Lorentz Transform does have a reference frame one can "prefer" and a way to translate to other reference frames. The Lorentz Transform is used in Special Relativity and is unaltered from the one Lorentz developed in his final theory. In SR you can certainly choose an inertial reference frame (anyone of them) then run all calculations relative to it (excluding extremes of GR we haven't tested yet). Solving the Twins Paradox is easy provided you stick with one reference frame choice from start to finish. Regardless of which frame is chosen you will get the right answer.

What the MM experiment proved was that if an ether does exist we don't need to reference this rest frame in any way to get the right answer. This is an important distinction from saying it doesn't exist. However, as far as the math we use is concerned we don't have to treat any reference frame as special so it doesn't exist in our models. Nevertheless, if we can choose a reference frame to run all our calculations, there is no reason nature couldn't do the same. There is no evidence nature works in this way but there is no evidence it can't work this way. Many people I've discussed Relativity with seem to think the ether concept is like the hypothesis of God existing. However, we can't use the God hypothesis to do anything useful in science. We CAN choose to prefer a reference frame and do very useful calculations solely off this single frame (or foliation in GR). At the very least if the ideas behind Relativity are 100% right this still allows us to approximate our existence as 3D with evolving time in our everyday lives and this means Relativity approaches classical in the classical limit.

Some people use the MM experiment or the Andromeda Paradox etc from Relativity to push too much as absolute fact while others try to use unknowns to devalue Relativity. What we know, verified by experiment, is more complicated and between these two extremes. In any case Local Lorentz Covariance is upheld in experiments and running the math of Relativity gets the right answers.

Even if some people find adding a preferred frame or foliation to theories makes it more pleasing to them (good for them) physicists aren't going to add one to the theories they use unless there is need to reference it. This is definitely a fair response as keeping the math and model simple is best. On the other hand, proponents of Relativity need to understand current limits to what's been verified and that alternative explanations are possible. Future experiments may also reveal the need for more complexities.

[David Cooper]

However, as far as the math we use is concerned we don't have to treat any reference frame as special so it doesn't exist in our models. Nevertheless, if we can choose a reference frame to run all our calculations, there is no reason nature couldn't do the same. There is no evidence nature works in this way but there is no evidence it can't work this way.

Except there is evidence that nature must work this way - no computer simulation of relativity can run the model without using a preferred frame of reference to coordinate the unfolding of events, and the same must apply to the actual universe. Any change in which frame of reference is used during the simulation requires a recalculation of where everything is, and that means many events which had previously been regarded as "happened" have to be undone while many events which had previously not happened must now have happened. Any change in the frame used to coordinate events requires some events to be run backwards and undone, and it's totally unreasonable to claim that the real universe does that.

The only way any pretence can be made of running the model without it depending on a preferred frame is by asserting that it is an eternal block universe so that changes in frame do not lead to any changes in the block, but if this approach is taken, an earlier phase must exist in which the block is generated under different laws of physics in which again a preferred frame is required, and again the same must apply to the real universe. Once you understand that, you can then see why no simulation of SR has ever been done without breaking the rules of the model because it is completely impossible for it to function by its own rules as they stand.

[dutch]

Any change in which frame of reference is used during the simulation requires a recalculation of where everything is, and that means many events which had previously been regarded as "happened" have to be undone while many events which had previously not happened must now have happened.

This is only an issue if you think planes of simultaneity stretching to infinity have real practicality we can test. Relativity is a local theory so we can only assign a "now" with certainty to an event taking place at a certain time and location. We don't know what "now" is anywhere else except at our current location. You're discussing the pitfalls of the Andromeda Paradox. The problem with the Andromeda Paradox is that we can't truly assign a "now" we're sure of in the Andromeda Galaxy. If we do assign a frame of reference and a "now" to events happening there we don't get that information for a few million years (Andromeda Galaxy is a few million light-years away). The plane of simultaneity swinging drastically into the future or past as we walk in different directions on Earth in a far off galaxy is simply meaningless in any experiment we currently could do.

https://en.wikipedia.org/wiki/Rietdijk%E2%80%93Putnam_argument

We can't undo events we know nothing about by simply changing frames of reference. Our maximum speed of information transfer is c so we can't undo events in our past light cone (unless somehow future experiments with faster than light information transfer prove otherwise). Einstein's Clock Synchronization is a convention used for simplicity and one of many we could chose.  We can't in principle test the one-way speed of light independent of two spatially separated clocks therefore we can't know what "now" is somewhere else.

Most attempts to negate the conventionality of this synchronization are considered refuted

https://en.wikipedia.org/wiki/Einstein_synchronisation
https://en.wikipedia.org/wiki/One-way_speed_of_light

I see your point and I definitely see why you think it's aesthetically pleasing to have a preferred frame. The question then becomes what frame of reference does nature prefer and how do you prove it? If you can't prove it then why put it in the theory? Why make physicists use an extra complexity in their math? Sure, you can acknowledge that SR definitely allows one to prefer a frame and everything we've tested in GR also could allow one to prefer a foliation (something many don't know). However, again we'd need to prove one is more special than another and Relativity predicts that we can't.

Relativity does predict weird things occurring at event horizons of black holes where an object contracts, time dilates, and it takes forever to reach the event horizon from the outside perspective (observer far outside the event horizon) but it passes through in finite time by the in-falling object's perspective. Many physicists have attempted to address this issue using very different ideas. In this case it seems the different perspectives are conflicted and perhaps they are. Perhaps GR may need modification at the extremes but then most physicists know this and we can't directly verify what happens at event horizons with current experiments. However, it's still the most accurate theory we have to explain gravity. We should be humble enough to know that all of our theories are subject to modification should the need arise.

I say we should use our theories to predict, we should keep our theories as simple as possible, trust them where verified but also keep our minds open to what's possible.

[David Cooper]

This is only an issue if you think planes of simultaneity stretching to infinity have real practicality we can test. Relativity is a local theory so we can only assign a "now" with certainty to an event taking place at a certain time and location. We don't know what "now" is anywhere else except at our current location.

It is very much an issue for any relativity simulation, and it must equally be an issue for the actual universe. Our inability to detect what's simultaneous doesn't eliminate the issue in either case - the objects in a simulation should not be allowed access to the key information which the program uses to coordinate events and they therefore can never determine which events are simultaneous, but the program has to control the unfolding of events in a rational way and is incapable of doing that without using a preferred frame mechanism. The universe must also control the unfolding of events in a rational way which doesn't involve unhappening events and rehappening them repeatedly, and it has no greater ability to do this than a simulation.

We can't undo events we know nothing about by simply changing frames of reference.

That's exactly the point. The universe has to do something and then stick with what it's done. To do anything else adds to its complexity (to try to hide the fact it depends on a preferred frame mechanism) rather than simplifying things.

I see your point and I definitely see why you think it's aesthetically pleasing to have a preferred frame.

It has nothing to do with aesthetics - this is entirely about needing a rational control for the unfolding of events to enable things to meet up when they've travelled to the same location by different paths and at different speeds. It cannot just be left to magic to do the coordination job. When a rocket moves away from a planet, its clock cannot both be running faster AND slower than it was running before.

The question then becomes what frame of reference does nature prefer and how do you prove it? If you can't prove it then why put it in the theory?

You can't pin it down, but the universe must have one regardless, just as a simulation must (and yet makes it impossible for the things within the simulation to pin it down). You cannot run the model without adding this to it, so without it the model is incomplete and cannot function correctly.

Why make physicists use an extra complexity in their math?

What extra complexity does it add? How do you run a simulation without it? You'd have to use magic, and that's why all simulations are either forced to use a preferred frame or must use more complex methods to obfuscate it which involve changing frames and recalculating what's happened and what has yet to happen. How can the universe coordinate the unfolding of events without it? It would have no option other than to use magic.

However, again we'd need to prove one is more special than another and Relativity predicts that we can't.

Within a simulation you can't prove which frame is more special either, but one frame must be. How is the universe any different? How can it achieve what is completely impossible in a simulation?

I say we should use our theories to predict, we should keep our theories as simple as possible, trust them where verified but also keep our minds open to what's possible.

Where keeping a theory simpler involves depending on magic for part of its mechanism, that should never be regarded as being simpler than a theory with a simpler component for that part of its mechanism which does not depend on magic.

[dutch]

First of all I'm playing Devil's Advocate with this topic.

It is very much an issue for any relativity simulation, and it must equally be an issue for the actual universe. Our inability to detect what's simultaneous doesn't eliminate the issue in either case - the objects in a simulation should not be allowed access to the key information which the program uses to coordinate events and they therefore can never determine which events are simultaneous, but the program has to control the unfolding of events in a rational way and is incapable of doing that without using a preferred frame mechanism. The universe must also control the unfolding of events in a rational way which doesn't involve unhappening events and rehappening them repeatedly, and it has no greater ability to do this than a simulation.

In Relativity space and time merge together to form something like a "4D block," a "Lorentzian manifold." This 4D concept is mathematically coherent and it gets the right answers. Do I personally think time is a fourth dimension in the fundamental sense? No. However, I can't find fault with treating spacetime like a 4D block.

You simply don't need to determine what events are simultaneous because only events have definite reality in Relativity and "simultaneity" doesn't. All you need are causal links and these links occurring at or below the speed of light maintains chronological ordering. All on its own, the constant speed of light maintains the ordering of events in Einstein's Relativity. Do I think it's more natural to have some form of preferred frame? Sure. Do I have my own problems with time as a fourth dimension? YES. You already know I'm well-versed in the math of LET based on posts in prior threads. I'm not trying to push one particular concept here.

That's exactly the point. The universe has to do something and then stick with what it's done. To do anything else adds to its complexity (to try to hide the fact it depends on a preferred frame mechanism) rather than simplifying things.

Not if the past, present, and future all "exist" already in a 4D "block." This is what Einstein thought later in his life. 3D reference frames we construct are like the 2D pictures we take of our 3D world. However, reference frames are 3D pictures of a 4D world so it's harder to visualize. We can take many different 2D pictures at different angles. These different angles will have different looking pictures but the underlying structure is the same. I'm not sure if this idea is fundamentally right but we can use it to make a model that makes the right predictions.

It has nothing to do with aesthetics - this is entirely about needing a rational control for the unfolding of events to enable things to meet up when they've traveled to the same location by different paths and at different speeds. It cannot just be left to magic to do the coordination job. When a rocket moves away from a planet, its clock cannot both be running faster AND slower than it was running before.

Einstein treated time like a dimension. Using this idea clocks don't tick at different rates in Relativity but rather they move differently through the "dimension of time." If spacetime (the below is for flat spacetime) is setup like the following as a 4D entity it works:

dτ² = dt² - dx² - dy² - dz²     (with c =1 units)

I have my own thoughts and I think there's deeper meaning behind why the equation above works but I can't prove it (without something transferring information FTL). All I can do is show that particular other conceptualizations are possible. I personally don't like mixing time with space in this way but the math does work.

Within a simulation you can't prove which frame is more special either, but one frame must be. How is the universe any different? How can it achieve what is completely impossible in a simulation?

It has to be a completely 4D simulation to work. The only way I know of is to use a block universe where the future, present, and past exist and have existed. Reference frames would be "rotations" in this 4D structure and time passing seems to be an "illusion" we experience.

You may call the 4D conceptualization "magic" but others think it's magical to have a hidden preferred frame/foliation. The important thing that we should focus on is having a mathematical model that works. We should also try to move ideas forward, keep our minds open, and run as many experiments as we can. 

[David Cooper]

In Relativity space and time merge together to form something like a "4D block," a "Lorentzian manifold." This 4D concept is mathematically coherent and it gets the right answers.

Note: it would be best to read the whole of this post before following the links so as to access the information in the right order.

There's another thread which has begun to cover this same issue, and as this subject is more in keeping with the title of that thread, this discussion should jump there instead of continuing here: https://www.thenakedscientists.com/forum/index.php?topic=70299.400  You don't need to read any of the thread before page 9 (the current page), or indeed any of it at all, but Phyti's posts from #405 onwards and my replies to him are possibly worth a look. You'll need to access the following page too if you are to make sense of the argument that's being referred to: http://www.magicschoolbook.com/science/relativity.html - on this page I discuss different Spacetime models including versions of the block universe, and I use a three-mode JavaScript interactive diagram (a minimalistic simulation) to illustrate their functionality, this crucial diagram being just short of half way down that page. What I do there is pin down the range of what's possible and show how different versions of the 4D Spacetime model actually perform.

It has to be a completely 4D simulation to work. The only way I know of is to use a block universe where the future, present, and past exist and have existed. Reference frames would be "rotations" in this 4D structure and time passing seems to be an "illusion" we experience.

You're right about that - unmodified SR can only eliminate a preferred frame (and all the contradictions) by using the eternal static block universe model, but the problem with that model is that it has no mechanism for the future to have been generated out of the past, which means that all the apparent chains of causality written through it are necessarily fake - the causation process has never been run, so what looks like a pattern of causation has to be explained instead by an infinite number of accidents which "happen" by luck (and by luck alone) to make it look as if the future was generated from the past. You can get away with a little bit of luck, but when the coincidences pile up and multiply infinitely, you soon find you're dealing with something that belongs to the realm of magic rather than physics. If the causation is actually to be real, we have no rational option other than to generate the block in order of causation, but that requires different physics. My interactive diagram explores how the block can be generated.

[alancalverd]

The MM experiment shows that the Maxwell equations adequately describe the propagation of electromagnetic radiation. If there was an aether, they wouldn't.

[David Cooper]

The MM experiment shows that the Maxwell equations adequately describe the propagation of electromagnetic radiation. If there was an aether, they wouldn't.

Do those equations use any terms which depend on measurements of distance, and if so, which frame do you use to measure those distances? If you then conclude that you aren't moving because you've already based your calculations on that assumption (when measuring the distances), then you're merely fooling yourself into thinking you're not moving.

[xersanozgen (OP)]

Within a simulation you can't prove which frame is more special either, but one frame must be. How is the universe any different?

Reference frames can be ranked in accordance with their capacity:

Microcosmos
.....


 An organism

A vehicle (e.g.  a train)

The Earth

Solar system

Milky way galaxy

Local group cluster

Super cluster

Universe

Multiple universe

.....

Most external Frame : Space /LCS (Light coordinate system)

 A hierarchical order is mentioned and we have a problem  to prefer most appropriate one.

We can examine an example to decide : The Earth-Sun relation. In fact the Sun deserves reference role; but we considered the Earth as primary reference frame because of our location on the Earth and we human had haven a wrong opinion like "the Sun turns around the Earth" for long years.

Therefore we must prefer to consider the most external frame for Light Kinematics. The velocity of light is the same value  c according to this frame (space). The theory SR allows this analysis; because the value of light's velocity is same according to every frame (In my opinion we measure always just  the universal velocity of light; but somebodies and SR label this value as local relative speed according to local place or moving body/source).

We can leave this mistake.

[David Cooper]

A hierarchical order is mentioned and we have a problem  to prefer most appropriate one.

A preferred frame has nothing to do with our preference, but it appears that I have been using the term in a non-standard way.

From Wikipedia: "In theoretical physics, a preferred or privileged frame is usually a special hypothetical frame of reference in which the laws of physics might appear to be identifiably different (simpler) from those in other frames."

I've been using the term "preferred frame" differently in that I don't intend it to mean that such a frame can be identified by us from within the universe (as it would only be identifiable to the universe itself), but I've used the term instead of "absolute frame" because the absolute frame may not be an available frame within the universe, leading to what I've been calling a preferred frame being a different frame at different locations. If our three space dimensions are all contained within the surface of an expanding 4D bubble, for example, the absolute frame could be based on the centre of that bubble, and all available 3D frames within the 3D surface of the bubble are moving relative to that absolute frame - this means that as you move through the 3D surface, the available 3D frame closest to being the absolute frame will change as you go along. So far as I know, there is no standard term to describe such a frame, which makes discussion of this subject awkward as almost every reference to a preferred or absolute frame needs to be packaged along with with lengthy disclaimers to spell out what isn't meant by them in the current context. What is most needed is a term for the local frame in which clocks at rest tick most quickly (the LFIWCARTMQ).

We all know though that there's no point in assuming that the LFIWCARTMQ is represented by the frame at which a planet, star, or galaxy is at rest. The LFIWCARTMQ is the frame in which an object at rest has light travel relative to it at c in all directions, but as there is no experiment that can measure the one-way speed of light, we can't identify it. What happens in SR is that the existence of such a frame is denied. If there are two objects moving relative to each other, you can consider either one to be at rest, and then the speed of light relative to the other object is not c (in most directions). You can then consider that other object to be at rest and assert that now the speed of light is c relative to it in all directions. That contradicts the measurements made from the first frame, but such contradictions are simply ignored. The justification for ignoring them ultimately leads us to the eternal block universe model where there is no actual speed of light at all, and all paths that light "takes" through the block are of zero distance and zero time.

[xersanozgen (OP)]

A preferred frame has nothing to do with our preference, but it appears that I have been using the term in a non-standard way.

I know this significant problem. The language capacity may be inadequate to tell the mental synthesis on the border of physics and metaphysics. Sometimes the phrases can be formed like "nursery rhyme" because of repeating same words. Naturally, scientific brain can think without words, and to tell by words cannot be easy. Besides collocutor can understand/interpret the sentences according to his/her mental filters and capacity and probably his aims that his mental references may be on different lane (*). Japan Haiku art may be effective for nature sciences area (as known, it is a telling form that has minimum potential of wrong understanding).

(*) We can see this problem on quantum philosophy evidently. A physicist / experimentalist discover a particle in accordance with his intuition. However quantum philosophist can say “he created a new entity by thinking”. This interpretation is like Berkeley mentality (purposive reading / manipulation  of the events).

[xersanozgen (OP)]

eternal block universe model where there is no actual speed of light at all, and all paths that light "takes" through the block are of zero distance and zero time.

Well, at last we will can perceive that the light is a forcemajor reference frame.

We must allow ourselves to consider this option.Yes, the light seems unmanageable/impossible but  the light has a fixed velocity, it never accelerates and light move linear, these qualities indicate the uniform motion that SR needs (originated Galilei relativity principle).

We can define the  "LCS" Light Coordinate System. The genuine/direct relative velocity of light is the value c according to LCS.

To analyze the motion of moving body according to LCS can be more consistent instead of the local centric mentality of SR.

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