Question on Lorentz transforms and relativity of simultaneity

roosh

dlouth15 wrote: »

Thanks. I'll comment on the second part first.Right. So from an instrumentalist point of view we can consider them as two interpretations of the same theory. You could answer any basic special relativity question in an exam either way; you might simply need to insert the word "measured" or "as measured" into the question and answer, but you would still get essentially the right answer.

Part of it is a matter of personal preference but I think there are some reasons for choosing one interpretation over the other.

With what we might call the "Lorentz" interpretation, on the plus side we have absolute space and time. On the negative side we have an Aether which is undetectable and motionless in the absolute sense. We therefore have the idea of absolute motion relative to this aether and again we have no way of measuring this absolute motion that each body has. Naive measurements of length and time no longer measure actual space and time since the measuring instruments have been modified in some way due to the absolute motion through the aether. Even if we are talking about relative motions far less than c, we still don't know what the actual physical length of objects is because our instruments are still distorted by motion through the Aether and we have no way of knowing what that absolute motion is.

With the "Einstein" interpretation we lose absolute space and time but we keep the idea that our instruments are actually measuring time and length; it is just that these quantities are now frame dependent. If we're dealing with relative motions very small compared to c, we can revert to Cartesian space and our everyday view of time and the meaning of length and time are those we are used to.

You win some and you lose some either way but I think you lose a bit more with the Lorentz version.

I'm not too sure of the history of aether theories but as far as I know the one we're discussing is the last of a line of them that were thought necessary to explain the transport of light. This last one has been modified so that instruments are distorted in such a way that the speed of light is always measured as constant. It is a kind of hack on an older theory. However, the Maxwell equations are expressed without any reference to an aether. So we don't really need it for this purpose any more and we can derive the Lorentz transformations directly from two simple postulates.

The "Einstein" interpretation in my view has the advantage of doing away with these explanations. We don't need any medium to explain the propagation of light so the theory shouldn't need to make use of it.

Plus and Minus
Some other things which might be considered on the "plus and minus" side of both theories is the subject of discussion in the thread on Absolute Motion. On the minus side of the Einsteinian interpretation, it seems that whatever we gain comes at the cost of having to assume that our past and future co-exist with our present - a seeming consequence of RoS.

Time
Another issue, where I think the Einsteinian (or perhaps Minkowskian) interpretation might be seriously questioned, is on the nature and existence of time. Einstein said that "Zeit is das was man an der Uhr abliest", a comment which could be interpreted in a number of ways; the common interpretation seems to be that "time is what a clock measures", and is echoed in your sentiments that, under the Einsteinian interpretation, we retain the idea that our instruments, clocks in this instance, actually measure time. That is the subject of a separate discussion in another thread - Serious Question on Clocks & Time The question is, can it be demonstrated that a clock measures physical time? The contention is that the idea that a clock measures physical time is just an assumption; that time is not a physical property to be measured i.e. it is not the object of measurement, rather it is a system of measurement. If we examine how clocks work we have a difficult time identifying where in the process something physical called "time" is actually measured. Einstein's statement would be re-interpreted as, time is that which one reads from a clock.


Aether
Something that I've wondered about is the idea that the Lorentz interpretation requires an aether, while the Einsteinian interpretation doesn't. If the Einsteinian interpretation says that light doesn't require an aether, can the same not be applied to the Lorentzian interpretation, because light either needs and aether, or it doesn't? If the mathematics seem to imply it, would it not just be a case of re-interpreting the mathematics; would it not be similar to the issue of time; where 't' remains in the equations, but has a different interpretation in both; relative time for Einstein but local time for Lorentz?

Is it possible, do you think, to have spacetime without the time; that is, just space?

dlouth15 wrote: »

The paradox can be resolved if you adopt the "Einstein" interpretation. The system is operating in one way only and we know this because we have fully described it operating in just one way. The Lorentz transformation (although with the "Einstein" interpretation) then shows that quantities will vary according to the frame of reference.

The price of resolving the paradox is abandoning the idea of space and time which is difficult because we've kind of evolved to view these things in a certain way.

But the apparent paradox arises from the Einsteinian interpretation, so I don't see how it can be resolved by that interpretation.

Morbert

roosh wrote: »

They do indeed have different co-ordinate descriptions of the same physical operation; these co-ordinate descriptions mean that one observer says that a single physical process will generate a non-sequential output from sequenced inputs, while the other says that the same output will be produced by the same physical inputs, from a different sequence of inputs.

It is the generation of a single output form two different orders of input which implies that the process operates in two different ways at once.


The physicality of the order of inputs appears to be immaterial, because both descriptions have the process physically beginning when the physical input reaches the system, despite the lack of a physical ordering.

It implies no such thing. The difference between the two descriptions is merely a hyperbolic rotation.

roosh

Morbert wrote: »

It implies no such thing. The difference between the two descriptions is merely a hyperbolic rotation.

But both descriptions are of how the observers brain functions in the same location, on the platform, inside his skull. One observer says that the brain inside the skull, of the observer on the platform, starts processing the stimuli in sequential order, producing a non-sequential output from sequential input, while the other says that the brain, inside his own skull, doesn't start processing the stimuli in sequential order but will produce a non-sequential output from non-sequential input.

That does seem to suggest that the brain, inside his skull, functions in two different ways at once.

Morbert

roosh wrote: »

But both descriptions are of how the observers brain functions in the same location, on the platform, inside his skull. One observer says that the brain inside the skull, of the observer on the platform, starts processing the stimuli in sequential order, producing a non-sequential output from sequential input, while the other says that the brain, inside his own skull, doesn't start processing the stimuli in sequential order but will produce a non-sequential output from non-sequential input.

That does seem to suggest that the brain, inside his skull, functions in two different ways at once.

Why does it suggest that? I can be in a car and describe it as stationary on a moving road. You can be on the road and describe the car as moving and the road as stationary. We have two different descriptions of the system, but not different physics. In a relativistic setting, simultaneity is as relative as velocity.

dlouth15

roosh wrote: »

Plus and Minus
Time
Another issue, where I think the Einsteinian (or perhaps Minkowskian) interpretation might be seriously questioned, is on the nature and existence of time. Einstein said that "Zeit is das was man an der Uhr abliest", a comment which could be interpreted in a number of ways; the common interpretation seems to be that "time is what a clock measures", and is echoed in your sentiments that, under the Einsteinian interpretation, we retain the idea that our instruments, clocks in this instance, actually measure time. That is the subject of a separate discussion in another thread - Serious Question on Clocks & Time The question is, can it be demonstrated that a clock measures physical time? The contention is that the idea that a clock measures physical time is just an assumption; that time is not a physical property to be measured i.e. it is not the object of measurement, rather it is a system of measurement. If we examine how clocks work we have a difficult time identifying where in the process something physical called "time" is actually measured. Einstein's statement would be re-interpreted as, time is that which one reads from a clock.

Like I said earlier, it comes down to personal preferences. You see the fact that Einstein uses a fairly conventional concept of time as a disadvantage; I see it as an advantage.

Aether
Something that I've wondered about is the idea that the Lorentz interpretation requires an aether, while the Einsteinian interpretation doesn't. If the Einsteinian interpretation says that light doesn't require an aether, can the same not be applied to the Lorentzian interpretation, because light either needs and aether, or it doesn't? If the mathematics seem to imply it, would it not just be a case of re-interpreting the mathematics; would it not be similar to the issue of time; where 't' remains in the equations, but has a different interpretation in both; relative time for Einstein but local time for Lorentz?

It comes down to what you prefer and what you can defend. In this case, you would probably need to explain how clocks are modified simply by their absolute motion when there's no Aether to interact with.

But the apparent paradox arises from the Einsteinian interpretation, so I don't see how it can be resolved by that interpretation.

We will have to agree to disagree on this one, I'm afraid. I don't think there's anything I can add at this point.

sponsoredwalk

roosh wrote: »

Another issue, where I think the Einsteinian (or perhaps Minkowskian) interpretation might be seriously questioned, is on the nature and existence of time.

Judging by your thread asking about the mathematics of special relativity & the responses in here it's pretty clear you do not fully understand the basic theory, yet you are really gung-ho about challenging it's fundamental principles - surely you know that this is equivalent to shooting in the dark? If you really feel the need to find the flaws in special relativity I challenge you to go through the first two chapters of this book, line by line, & point out the flaws without reference to anything else but that textbook. To be realistic, just go through the first 12 pages, four sections, & talk about all the areas where you feel the material should be seriously questioned, or more realistically - post questions about the material & ensure you fully understand it to eliminate any niggling little issues you have with the basics before going back to challenging it's fundamental structure.

If that book is too hard we could go through these four videos on SR:

https://www.youtube.com/watch?v=4JbaI5Q7FSs

roosh

Morbert wrote: »

Why does it suggest that? I can be in a car and describe it as stationary on a moving road. You can be on the road and describe the car as moving and the road as stationary. We have two different descriptions of the system, but not different physics. In a relativistic setting, simultaneity is as relative as velocity.

The issue isn't quite as simplistic as describing a car as moving or as stationary, relative to certain objects. The issue is that, as has been stated, we have a single physical process which seems to operate in two different ways. The brain in the skull, of the observer on the platform, produces the same output form two different orders of input; one description says that the process starts physically functioning in sequential order, while the other says that it starts physically functioning non-sequentially.

In the car example it would be like one observer saying that the front tyres start physically rotating before the rear tyres, while the other observer says that the front tyres don't start physically rotating before the rear tyres, that both sets start physically rotating together - where the travel time of light to either of the observers doesn't resolve the issue.

roosh

dlouth15 wrote: »

Like I said earlier, it comes down to personal preferences. You see the fact that Einstein uses a fairly conventional concept of time as a disadvantage; I see it as an advantage.

I would say that the definition used by Einstein is a conventional misconception, and represents an additional assumption required by the theory; an assumption I don't think is justified. That "time is what one reads from a clock" doesn't imply that time is physical, indeed, when we look at how a clock works it's difficult to see how time can be considered to be the object of measurement; it seems that this is something which has to be assumed.

Indeed, when we consider the fairly mainstream interpretation of Minkowski spacetime, that isn't the only thing which needs to be assumed; the conclusions that an observers past and future co-exist with their present must also be assumed.

dlouth15 wrote: »

It comes down to what you prefer and what you can defend. In this case, you would probably need to explain how clocks are modified simply by their absolute motion when there's no Aether to interact with.

If we consider light clocks in absolute motion, then we can see that the "tick-tock" cycle of the clocks isn't given by the simplistic equation of twice the distance from the midpoint of one mirror to the midpoint of the other (2d). Only a hypothetical clock at absolute rest would have such a "tick-tock" cycle. This is because the trajectory of the photon in the light clock would be affected by the motion of the mirror.

To visualise the issue you only need to consider the Einsteinian thought experiment from the perspective of one observer, the observer on the platform for example. We can remove the platform and have the observer in the hypothetical absolute rest frame. The path of the photon in the relatively moving clock would trace a path not equal to 2d, but as given by the pythagorean theorem; hence it would tick at a different rate to the clock at absolute rest.

The absolute rest frame isn't necessary, because it is possible that every object in the universe is in absolute motion, but it can be helpful to visualise the issue.

dlouth15 wrote: »

We will have to agree to disagree on this one, I'm afraid. I don't think there's anything I can add at this point.

I thought that we had almost reached agreement; you said that the issue appeared to be paradoxical but that the paradox arises as a consequence of the constancy of c. I mentioned that the constancy of c can be distinguished from a constant measurement of c, and that there is a possible interpretation of relativity which allows for this, and would resolve the apparent paradox.

Just to understand your position, are you content that there is an apparent paradox?

roosh

sponsoredwalk wrote: »

Judging by your thread asking about the mathematics of special relativity & the responses in here it's pretty clear you do not fully understand the basic theory, yet you are really gung-ho about challenging it's fundamental principles - surely you know that this is equivalent to shooting in the dark? If you really feel the need to find the flaws in special relativity I challenge you to go through the first two chapters of this book, line by line, & point out the flaws without reference to anything else but that textbook. To be realistic, just go through the first 12 pages, four sections, & talk about all the areas where you feel the material should be seriously questioned, or more realistically - post questions about the material & ensure you fully understand it to eliminate any niggling little issues you have with the basics before going back to challenging it's fundamental structure.

If that book is too hard we could go through these four videos on SR:

https://www.youtube.com/watch?v=4JbaI5Q7FSs

cheers SW, I've had a look at the first of the 4 videos and have gone through the first 6 pages of the book, but it all appears to be information I have encountered previously, in discussions with people on here and elsewhere, as well as through various lectures, videos, and papers.

I would agree that I don't fully understand the theory, and I wouldn't have the necessary understanding of the mathematics to answer mathematical problems associated with the theory, but this particular discussion is limited to a very basic point, for which only a basic understanding of the limited scope of the discussion is necessary. Essentially, we are just taking what relativity says about a particular scenario and following the consequences. I'm not necessarily questioning the formulation of the theory as I am the interpretation of it, given that there is, apparently, an alternative interpretation of the theory for which the apparent paradox does not arise.

The issue
I presume that you have been following the issue, to a certain extent, to say that you chose to comment; you will be familiar with what the apparent paradox is then; namely that we have a single physical process/system, which generates the same output from a differing orders of input; where the physicality of the order of the inputs doesn't matter, because the process starts to operate physically, when the inputs enter the system, and in the order they enter.



Little more than a very basic understanding is required to understand the alleged paradox.

Morbert

roosh wrote: »

The issue isn't quite as simplistic as describing a car as moving or as stationary, relative to certain objects. The issue is that, as has been stated, we have a single physical process which seems to operate in two different ways. The brain in the skull, of the observer on the platform, produces the same output form two different orders of input; one description says that the process starts physically functioning in sequential order, while the other says that it starts physically functioning non-sequentially.

In the car example it would be like one observer saying that the front tyres start physically rotating before the rear tyres, while the other observer says that the front tyres don't start physically rotating before the rear tyres, that both sets start physically rotating together - where the travel time of light to either of the observers doesn't resolve the issue.

It is absolutely as simple. We do not have a physical process which seems to operate in two different ways. We have a single physical process and two equivalent coordinate descriptions. There is no issue to resolve.

roosh

Morbert wrote: »

It is absolutely as simple. We do not have a physical process which seems to operate in two different ways. We have a single physical process and two equivalent coordinate descriptions. There is no issue to resolve.

The issue is that the co-ordinate descriptions seem to imply that the single physical process operates in two different ways, at once.

We have a brain in a skull and two descriptions of how it operates in the skull; it doesn't necessarily need to be a brain, I think it can be extended to any complex or simple system.

Each description says that the physical process begins operating when the input makes contact with the respective receptors; one description says that the physical input makes contact with the receptors in sequential order, and so the process physically begins operating in sequential order, to produce a non-sequential output; the other says that the physical input does not make contact non-sequentially, and that the process starts operating in unison to produce a non-sequential output.


There we have two descriptions of the same physical process, where the functioning of the physical process is described as being different, all inside the skull of a single observer. This does seem to imply that the brain, or any given process, functions in two different ways at once.

Morbert

roosh wrote: »

The issue is that the co-ordinate descriptions seem to imply that the single physical process operates in two different ways, at once.

We have a brain in a skull and two descriptions of how it operates in the skull; it doesn't necessarily need to be a brain, I think it can be extended to any complex or simple system.

Each description says that the physical process begins operating when the input makes contact with the respective receptors; one description says that the physical input makes contact with the receptors in sequential order, and so the process physically begins operating in sequential order, to produce a non-sequential output; the other says that the physical input does not make contact non-sequentially, and that the process starts operating in unison to produce a non-sequential output.


There we have two descriptions of the same physical process, where the functioning of the physical process is described as being different, all inside the skull of a single observer. This does seem to imply that the brain, or any given process, functions in two different ways at once.

I.e The difference between the two descriptions is the simultaneity of events. If presentism is true, these descriptions are physically distinct. However, under the 4D spacetime interpretation, the only difference between the two is a hyperbolic rotation.

roosh

Morbert wrote: »

I.e The difference between the two descriptions is the simultaneity of events. If presentism is true, these descriptions are physically distinct. However, under the 4D spacetime interpretation, the only difference between the two is a hyperbolic rotation.

That would mean then, that the apparent paradox is resolved only if we assume that our past and future co-exist with our present, and that time is physical and measurable by a clock; that is, if we employ circular reasoning.

Morbert

roosh wrote: »

That would mean then, that the apparent paradox is resolved only if we assume that our past and future co-exist with our present, and that time is physical and measurable by a clock; that is, if we employ circular reasoning.

This thread was started regarding questions about the consistency of relativity of simultaneity.

While you might feel it is circular reasoning, do you accept that it is consistent.

If you do, then we can go on to discuss whether it is circular reasoning (it isn't).

roosh

Morbert wrote: »

This thread was started regarding questions about the consistency of relativity of simultaneity.

While you might feel it is circular reasoning, do you accept that it is consistent.

If you do, then we can go on to discuss whether it is circular reasoning (it isn't).

In a discussion with someone else, they raised a similar point about 4D spacetime; they said that, according to the relatively moving observer, one side of the other observer's head (on the platform) is in the past with respect to the other side of his own head. This would seem to be what is necessitated; would you agree with that?

Morbert

roosh wrote: »

In a discussion with someone else, they raised a similar point about 4D spacetime; they said that, according to the relatively moving observer, one side of the other observer's head (on the platform) is in the past with respect to the other side of his own head. This would seem to be what is necessitated; would you agree with that?

Yes. In 4D spacetime, that would be no more remarkable than one side of the other observer's head being "to the left" of the other side.

roosh

Morbert wrote: »

Yes. In 4D spacetime, that would be no more remarkable than one side of the other observer's head being "to the left" of the other side.

In that case, I would say that the resolution of the apparent paradox requires the assumption, on behalf of observers, that their past and future co-exist with their present, and that time is physical and measurable with a clock.

Morbert

roosh wrote: »

In that case, I would say that the resolution of the apparent paradox requires the assumption, on behalf of observers, that their past and future co-exist with their present, and that time is physical and measurable with a clock.

Which brings us back to the issue being hashed out in the philosophy forum.

roosh

Morbert wrote: »

Which brings us back to the issue being hashed out in the philosophy forum.

Indeed.

roosh

Had posted this as an edit, but not sure if it will show up as a new notification, so I said I'd post it separately:

Would it be fair to say that it comes down to a question of the minkowskian block universe vs presentism?

Morbert

roosh wrote: »

Had posted this as an edit, but not sure if it will show up as a new notification, so I said I'd post it separately:

Would it be fair to say that it comes down to a question of the minkowskian block universe vs presentism?

Yes