Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest
Question on Lorentz transforms and relativity of simultaneity
Comments
-
-
So the physical processes of the brain are affected?
Yes, but only in the usual relativistic, "kinematic" sense. We could bring the conversation back to the kinematic vs. dynamic debate, but I believe the purpose of this thread was to determine whether or not there was a contradiction in the Einsteinian interpretation of events. So even if you still don't like the idea of spacetime, you should at least accept that there is no contradiction or true paradox.0 -
Is that the usual kinematic sense in which contractions aren't physical and physical processes aren't affected?Yes, but only in the usual relativistic, "kinematic" sense. We could bring the conversation back to the kinematic vs. dynamic debate, but I believe the purpose of this thread was to determine whether or not there was a contradiction in the Einsteinian interpretation of events. So even if you still don't like the idea of spacetime, you should at least accept that there is no contradiction or true paradox.0 -
Is that the usual kinematic sense in which contractions aren't physical and physical processes aren't affected?
The geometry of spacetime does have observable physical effects. A twin returning on a spaceship will be much younger than the twin staying at home. Clocks at different locations in a uniform gravitational field will tick at different rates. Relativity predicts all of these effects. What you are objecting to is the idea that the underlying kinematics of these effects, rather than some set of physical dynamics, is more fundamental, because that contradicts presentism.0 -
The asymmetry between the reference frames is what is used to account for the twin "paradox", but asymmetry isn't a factor here. The issue is that the apparent implication is that an inertially moving brain will behave in two physically different ways. According to S' if the retinae are stimulated in a given order, the brain will produce an unordered experience for the observer on the platform [in this particular case], however, if the retinae are stimulated in the same order, for the observer on the train, then the brain will generate an ordered experience.The geometry of spacetime does have observable physical effects. A twin returning on a spaceship will be much younger than the twin staying at home. Clocks at different locations in a uniform gravitational field will tick at different rates. Relativity predicts all of these effects. What you are objecting to is the idea that the underlying kinematics of these effects, rather than some set of physical dynamics, is more fundamental, because that contradicts presentism.
While S' says that a non-ordered experience will be produced from ordered retinae stimulation, for the observer on the platform, S would say that the brain would produce an ordered experience from ordered retinae stimulation [in this particular scenario].0 -
The asymmetry between the reference frames is what is used to account for the twin "paradox", but asymmetry isn't a factor here. The issue is that the apparent implication is that an inertially moving brain will behave in two physically different ways. According to S' if the retinae are stimulated in a given order, the brain will produce an unordered experience for the observer on the platform [in this particular case], however, if the retinae are stimulated in the same order, for the observer on the train, then the brain will generate an ordered experience.
While S' says that a non-ordered experience will be produced from ordered retinae stimulation, for the observer on the platform, S would say that the brain would produce an ordered experience from ordered retinae stimulation [in this particular scenario].
That is not true in the general sense that you are implying. Observer S' will say that observer S experiences certain non-simultaneous events as simultaneous, but similarly, observer S says observer S' will experience certain non-simultaneous events as simultaneous. Relativity says neither S nor S' is more physically correct than the other.
To phrase it generally. For a given reference frame X, an observer that X labels as stationary will experience events that X labels simultaneous as simultaneous. An observer that X labels as moving will experience events that X labels simultaneous as non-simultaneous.
There is no consequential difference between the twin paradox and this. Simply consider the cases when the person on the train jumps to the ground, or the person on the platform jumps onto the train. Or the the case where the twin never returns to earth. In fact, in the same way that the equivalence principle (acceleration and gravity are locally equivalent) solves the twin paradox without the need to resort to asymmetry, it can solve your problem without the need to resort to asymmetry.
Also, again, there is no consequential difference between a brain modelled as a sophisticated set of neurons, and a brain modelled as two clocks. So if you accept one model as consistent, you are logically compelled to accept the other as consistent as well.0 -
The issue isn't resolved by saying that in certain situations each says the same thing about the other.That is not true in the general sense that you are implying. Observer S' will say that observer S experiences certain non-simultaneous events as simultaneous, but similarly, observer S says observer S' will experience certain non-simultaneous events as simultaneous. Relativity says neither S nor S' is more physically correct than the other.
To phrase it generally. For a given reference frame X, an observer that X labels as stationary will experience events that X labels simultaneous as simultaneous. An observer that X labels as moving will experience events that X labels simultaneous as non-simultaneous.
There is no consequential difference between the twin paradox and this. Simply consider the cases when the person on the train jumps to the ground, or the person on the platform jumps onto the train. Or the the case where the twin never returns to earth. In fact, in the same way that the equivalence principle (acceleration and gravity are locally equivalent) solves the twin paradox without the need to resort to asymmetry, it can solve your problem without the need to resort to asymmetry.
Also, again, there is no consequential difference between a brain modelled as a sophisticated set of neurons, and a brain modelled as two clocks. So if you accept one model as consistent, you are logically compelled to accept the other as consistent as well.
The issue is that the reference frames imply that inertially moving brains, in a region of space where gravity is equal for relatively moving observers - such that the equivalence principle doesn't apply - will physically process stimuli in two different ways. In the given example, S' says that the brain of the observer on the platform will process stimuli, received in a given order, as an unordered experience, while S says that, for the observer on the platform, all stimuli received in a given order will result in an ordered experience. So ordered stimuli will result in the brain physically producing two mutually exclusive experiences.
S' also says that for the observer on the train, if the stimuli are received in the given order, they will result in an ordered experience, unlike the observer on the platform. This suggests that the physical operation of the brain is different on the platform than on the train, where neither asymmetry or the equivalence principle apply.0 -
The issue isn't resolved by saying that in certain situations each says the same thing about the other.
The issue is that the reference frames imply that inertially moving brains, in a region of space where gravity is equal for relatively moving observers - such that the equivalence principle doesn't apply - will physically process stimuli in two different ways. In the given example, S' says that the brain of the observer on the platform will process stimuli, received in a given order, as an unordered experience, while S says that, for the observer on the platform, all stimuli received in a given order will result in an ordered experience. So ordered stimuli will result in the brain physically producing two mutually exclusive experiences.
S' also says that for the observer on the train, if the stimuli are received in the given order, they will result in an ordered experience, unlike the observer on the platform. This suggests that the physical operation of the brain is different on the platform than on the train, where neither asymmetry or the equivalence principle apply.
Again (and again) relativity says brains moving relative to each other will not process events the same way. That is not the issue. The issue is your baseless insistence that this is due to mysterious dynamics, rather than the geometry of spacetime.0 -
What it says is that the same physical brain will physically process ordered stimuli in two different ways; according to one reference frame the brain will physically process ordered stimuli to produce an unordered experience. The other reference frame says that the same brain will produce an ordered experience from ordered stimuli.Again (and again) relativity says brains moving relative to each other will not process events the same way. That is not the issue. The issue is your baseless insistence that this is due to mysterious dynamics, rather than the geometry of spacetime.0 -
What it says is that the same physical brain will physically process ordered stimuli in two different ways; according to one reference frame the brain will physically process ordered stimuli to produce an unordered experience. The other reference frame says that the same brain will produce an ordered experience from ordered stimuli.
Yes. For a given reference frame X, an observer that X labels as stationary will experience events that X labels simultaneous as simultaneous. An observer that X labels as moving will experience events that X labels simultaneous as non-simultaneous.0 -
Advertisement
-
S': A physical brain which receives ordered stimuli will produce an unordered experience.Yes. For a given reference frame X, an observer that X labels as stationary will experience events that X labels simultaneous as simultaneous. An observer that X labels as moving will experience events that X labels simultaneous as non-simultaneous.
S: The same physical brain which receives ordered stimuli will produce an ordered experience, for any of the infinite permutations of ordered stimuli.
The same brain produces two different experiences from ordered stimuli.0 -
S': A physical brain which receives ordered stimuli will produce an unordered experience.
S: The same physical brain which receives ordered stimuli will produce an ordered experience, for any of the infinite permutations of ordered stimuli.
The same brain produces two different experiences from ordered stimuli.
The same brain produces one experience from the stimulus. The description of the stimulus is frame-dependent.
Fixed.0 -
-
-
-
S': A physical brain which receives ordered stimuli will produce an unordered experience.
S: The same physical brain which receives ordered stimuli will produce an ordered experience, for any of the infinite permutations of ordered stimuli.
The same brain produces two different experiences from ordered stimuli.
Can you expand on this a little more? Do you mean one brain in two physical locations? (for example on a train S and simultaneously on the platform S'?)
Or do you mean two identical brains in two different locations as above?0 -
The same brain, in the same physical location, physically operating in two different ways.citrus burst wrote: »Can you expand on this a little more? Do you mean one brain in two physical locations? (for example on a train S and simultaneously on the platform S'?)
Or do you mean two identical brains in two different locations as above?
One reference frame (S) says that, for the the observer on the platform, the infinite permutations of ordered stimuli will cause the brain to produce an ordered experience.
S' says that, for the same brain in the same location, ordered stimuli will cause the brain to produce and unordered experience.
The physicality of the ordering doesn't matter, because we can see that if the same brain were located on the train, it would generate an ordered experience despite the fact that the ordering isn't physical.0 -
The same brain, in the same physical location, physically operating in two different ways.
Why would one brain operate in two or more ways? (Unless its designed to do so) Does your brain do this? Mine doesn't.
Well is the brain here?One reference frame (S) says that, for the the observer on the platform, the infinite permutations of ordered stimuli will cause the brain to produce an ordered experience.
Or here?S' says that, for the same brain in the same location, ordered stimuli will cause the brain to produce and unordered experience.
Can't be both places.One reference frame (S) says that, for the the observer on the platform, the infinite permutations of ordered stimuli will cause the brain to produce an ordered experience.
S' says that, for the same brain in the same location, ordered stimuli will cause the brain to produce and unordered experience.
Whats the difference between an ordered and an unordered experience?
So you agree that the ordering of events is a relative thing?The physicality of the ordering doesn't matter, because we can see that if the same brain were located on the train, it would generate an ordered experience despite the fact that the ordering isn't physical.
Slow down the speed of light for a second, to 3 m/s (or alternatively make the distances really big) and have a think about this. You are sitting in your car at a cross road. The traffic lights are red. The lights that are closer to you will turn green before the lights that are further away. Cars further away from the lights will have a longer time interval before the lights change for them. The lights will turn green simultaneous only for someone equidistant from both lights. All others will have a differently ordered experience.
Do you agree with this?0 -
According to relativity it should.citrus burst wrote: »Why would one brain operate in two or more ways? (Unless its designed to do so) Does your brain do this? Mine doesn't.
The brain is in the skull of the observer on the platform; the location on the platform is described by both S and S'.citrus burst wrote: »Well is the brain here?
Or here?
Can't be both places.
Ordered experience is where you see one light flash first and then the other, unordered is where there is no ordering of the light flashes, they occur together.citrus burst wrote: »Whats the difference between an ordered and an unordered experience?
I'm saying that the physicality of the ordering doesn't, apparently, matter.citrus burst wrote: »So you agree that the ordering of events is a relative thing?
I would agree with that, but it doesn't represent the issue.citrus burst wrote: »Slow down the speed of light for a second, to 3 m/s (or alternatively make the distances really big) and have a think about this. You are sitting in your car at a cross road. The traffic lights are red. The lights that are closer to you will turn green before the lights that are further away. Cars further away from the lights will have a longer time interval before the lights change for them. The lights will turn green simultaneous only for someone equidistant from both lights. All others will have a differently ordered experience.
Do you agree with this?
There are two traffic lights, either side; you are located equidistant from both lights; the lights turn green in the given order, one first then the other; the light from each green light reaches your retinae in that order; what experience would you expect to have?0 -
Advertisement
-
It depends on the motion of the observer making the measurement. Under certain circumstances, an observer might measure non-simultaneous changes in the lights, yet I have an experience of simultaneous change. Strange, but if special relativity is correct, true.There are two traffic lights, either side; you are located equidistant from both lights; the lights turn green in the given order, one first then the other; the light from each green light reaches your retinae in that order; what experience would you expect to have?
If the observer, on the other hand, is not moving relative to me then, his measurements will correspond to my experience. In everyday life, of course, our motions are generally so slow compared to the speed of light that it really doesn't make a difference, and both the observer and I will agree on the simultaneity/non-simultaneity of events for practical purposes.0 -
-
The production of experience by the brain, from the stimuli, is a phyiscal process*; one reference frame says that the physical process will produce an unordered experience from ordered stimuli, while the other reference frame says that the physical process will only produce an unordered experience from unordered stimuli; it also says that for the infinite combination of unordered stimuli, an unordered experience will be produced every time.There exists two different descriptions of how his brain functions inside his skull. We have been over all of this already.
While the ordering of the stimuli might not be physical, the process by which the brain produces experience is*. If an unordered experience is produced by both unordered and ordered stimuli, it implies that the physical process functions in two different ways. Where the body, apparently, doesn't distinguish between physically and non-physically ordered stimuli.
*the assumption upon which we are operating.0 -
citrus burst wrote: »So you agree that the ordering of events is a relative thing?
Slow down the speed of light for a second, to 3 m/s (or alternatively make the distances really big) and have a think about this. You are sitting in your car at a cross road. The traffic lights are red. The lights that are closer to you will turn green before the lights that are further away. Cars further away from the lights will have a longer time interval before the lights change for them. The lights will turn green simultaneous only for someone equidistant from both lights. All others will have a differently ordered experience.
Do you agree with this?
If you agree with citrus burst then would you not also agree that the bit of your post I have put in bold needs to be qualified by information about the motion of the observer making that measurement?I would agree with that, but it doesn't represent the issue.
There are two traffic lights, either side; you are located equidistant from both lights; the lights turn green in the given order, one first then the other; the light from each green light reaches your retinae in that order; what experience would you expect to have?
If you leave this information out, the tendency is to assume that this observer is either also standing somewhere on the road or is the same as me at the equidistant point, in which case the standard commonsense (but in general wrong) notions about simultaneity apply.
It all comes down to the speed of light and the fact that it is constant in all frames. Imagine that at the point of the lights changing as observed by "me" stationary and equidistant from the two lights, I also see a moving observer also equidistant between the lights but moving towards one of them. As citrus burst points out, that observer will see the lights changing non-simultaneously.
Now the question is whether this second observer making a valid observation as to the simultaneity/non-simultaneity of the lights changing. The answer is that it is valid due to the a) the idea that the laws of physics should be the same in all frames of reference and b) that the speed of light is constant in all frames.
If you agree with those two statements, then you must logically agree that this moving observer is making a perfectly valid observation. By valid I mean that that it is valid regardless of the means by which that observer makes the observation.
The observer could set up a system of synchronized clocks that move with the observer and these clocks record the timing the changing of the lights when they are right next to the lights as they change, and these clocks would record different times. If this were not so, we would have to invalidate either a) the idea that the laws of physics should be the same in all frames of reference or b) that the speed of light is constant in all frames. But you agree with a and b.0 -
The production of experience by the brain, from the stimuli, is a phyiscal process*; one reference frame says that the physical process will produce an unordered experience from ordered stimuli, while the other reference frame says that the physical process will only produce an unordered experience from unordered stimuli; it also says that for the infinite combination of unordered stimuli, an unordered experience will be produced every time.
While the ordering of the stimuli might not be physical, the process by which the brain produces experience is*. If an unordered experience is produced by both unordered and ordered stimuli, it implies that the physical process functions in two different ways. Where the body, apparently, doesn't distinguish between physically and non-physically ordered stimuli.
*the assumption upon which we are operating.
These are all frame-dependent descriptions of the same physical process. There are two different ways to describe the same process, and neither is more correct than the other. We really have been over all of this already.0 -
Thanks, I am familiar with the above by now. We don't necessarily need to add the qualifying statement, but we can; we can say that according to you the lights change in an unordered manner, but according to the other relatively moving observer they change in a different order. The statement is still true, you are sitting in your car and the lights change in the given order and the photons reach your retinae in that order. The other statement is also true, your are sitting in your car and the lights change in an unordered manner and the photons arrive at your retinae, unordered. Both of these result in an unordered experience being produced by the brain.If you agree with citrus burst then would you not also agree that the bit of your post I have put in bold needs to be qualified by information about the motion of the observer making that measurement?
If you leave this information out, the tendency is to assume that this observer is either also standing somewhere on the road or is the same as me at the equidistant point, in which case the standard commonsense (but in general wrong) notions about simultaneity apply.
It all comes down to the speed of light and the fact that it is constant in all frames. Imagine that at the point of the lights changing as observed by "me" stationary and equidistant from the two lights, I also see a moving observer also equidistant between the lights but moving towards one of them. As citrus burst points out, that observer will see the lights changing non-simultaneously.
Now the question is whether this second observer making a valid observation as to the simultaneity/non-simultaneity of the lights changing. The answer is that it is valid due to the a) the idea that the laws of physics should be the same in all frames of reference and b) that the speed of light is constant in all frames.
If you agree with those two statements, then you must logically agree that this moving observer is making a perfectly valid observation. By valid I mean that that it is valid regardless of the means by which that observer makes the observation.
The observer could set up a system of synchronized clocks that move with the observer and these clocks record the timing the changing of the lights when they are right next to the lights as they change, and these clocks would record different times. If this were not so, we would have to invalidate either a) the idea that the laws of physics should be the same in all frames of reference or b) that the speed of light is constant in all frames. But you agree with a and b.
The underlying physical process is independent of how it is decribed; what we have is a single physical brain which produces experiences based on the stimuli it receives; we have two conflicting orderings of the stimuli, where the physicality of the ordering is apparently irrelevant; the brain will process them either way.These are all frame-dependent descriptions of the same physical process. There are two different ways to describe the same process, and neither is more correct than the other. We really have been over all of this already.
So, we have a single physical process and two conflicting orderings, where the physicality of the orderings is immaterial; these two conflicting orderings result in the same experience output; this implies that the physical process must work in two different ways, in the observers skull.0 -
Advertisement
-
-
What I don't nderstand is that on the one hand you say that the ordering/simultaneity is frame dependent yet at the same time say that a qualifying statement is not necessary. If something is dependent on some factor and you want to see the consequences then you must specify it. If you don't then there's ambiguity and a variety of outcome is possible depending what assumptions are made.Thanks, I am familiar with the above by now. We don't necessarily need to add the qualifying statement, but we can; we can say that according to you the lights change in an unordered manner, but according to the other relatively moving observer they change in a different order. The statement is still true, you are sitting in your car and the lights change in the given order and the photons reach your retinae in that order. The other statement is also true, your are sitting in your car and the lights change in an unordered manner and the photons arrive at your retinae, unordered. Both of these result in an unordered experience being produced by the brain.0 -
Just to elaborate on my previous post.
You have accepted the frame dependency of time-ordering/simultaneity. You will no doubt then agree that it is not enough simply to say that two events are simultaneous or non-simultaneous - that is incomplete. What you need to do is explicitly describe the frame in which the events are simultaneous or not.
So for example:There are two traffic lights, either side; you are located equidistant from both lights; the lights turn green in the given order, one first then the other; the light from each green light reaches your retinae in that order; what experience would you expect to have?
Given the frame dependency which you accept is valid, can you see that this is an incomplete description of the system? Yes, it is fine for everyday experience but not for special relativity. What I suggest is that you explicitly state the frames of reference wherever ordering, simultaneity arises in that sentence.
If you leave them out, then false paradoxes arise. This I believe is the crux of the issue. If you don't like frames of reference then you must at least state the motion of whatever observer(s) has made the measurement of the ordering of the events.
If you can't see why this is necessary I suggest you indulge me and do it anyway. I believe the apparent paradoxes will disappear when you do this.0 -
which is immaterial because the brain will still, apparently, process them in the order they are received, despite the lack of physical ordering; we can see this from the fact that the observer on the train will have an ordered experience, despite the lack of physical ordering of the events.The ordering is not physical.
Essentially what we have is a single physical process with two different inputs, resulting in the same output; this implies that the physical process behaves in two different ways, in the skull of the observer.0 -
What I don't nderstand is that on the one hand you say that the ordering/simultaneity is frame dependent yet at the same time say that a qualifying statement is not necessary. If something is dependent on some factor and you want to see the consequences then you must specify it. If you don't then there's ambiguity and a variety of outcome is possible depending what assumptions are made.
We are dealing with two statements about the physical world which are supposedly true, so we can simply describe the two scenarios and see what results we would expect.Just to elaborate on my previous post.
You have accepted the frame dependency of time-ordering/simultaneity. You will no doubt then agree that it is not enough simply to say that two events are simultaneous or non-simultaneous - that is incomplete. What you need to do is explicitly describe the frame in which the events are simultaneous or not.
So for example:
Given the frame dependency which you accept is valid, can you see that this is an incomplete description of the system? Yes, it is fine for everyday experience but not for special relativity. What I suggest is that you explicitly state the frames of reference wherever ordering, simultaneity arises in that sentence.
If you leave them out, then false paradoxes arise. This I believe is the crux of the issue. If you don't like frames of reference then you must at least state the motion of whatever observer(s) has made the measurement of the ordering of the events.
If you can't see why this is necessary I suggest you indulge me and do it anyway. I believe the apparent paradoxes will disappear when you do this.
The qualifying statements aren't necessary because the physicality of the order of events is immaterial; the brain will, apparently, process stimuli regardless of the physical ordering, as can be seen from the experience of the observer on the train.
In one scenario you are sitting in your car between two lights, the lights flash in a given order and the light reaches you in that order.
In the other scenario the lights flash in an unordered sequence, and the light arrives at you without any sequential order.
These are two physical world scenarios which are, supposedly, equally true.
Ultimately, what we have is a single physical process with two different inputs giving rise to the same output; this implies that the physical process behaves in two different ways.0 -
Advertisement
-
Again, you leave out any statement about frames of reference which you accept elsewhere the descriptions depend on.We are dealing with two statements about the physical world which are supposedly true, so we can simply describe the two scenarios and see what results we would expect.
The qualifying statements aren't necessary because the physicality of the order of events is immaterial; the brain will, apparently, process stimuli regardless of the physical ordering, as can be seen from the experience of the observer on the train.
In one scenario you are sitting in your car between two lights, the lights flash in a given order and the light reaches you in that order.
In the other scenario the lights flash in an unordered sequence, and the light arrives at you without any sequential order.
These are two physical world scenarios which are, supposedly, equally true.
Ultimately, what we have is a single physical process with two different inputs giving rise to the same output; this implies that the physical process behaves in two different ways.
If a complete description of something in general depends on factors A and B but you leave out B in your specific examples then you are going to get inconsistent results. The A factor might be the same in both examples but the B factors might vary but by omitting B we leave out crucial information leading to the inconsistency. This is a logical problem rather than anything to do with special relativity.
How is it you accept this yet don't put it into practice?0 -
We have a physical scenario, where you are sitting in your car; the lights change in non-sequential order and the light reaches you in this order; this physical scenario is true; it's true in the physical world.Again, you leave out any statement about frames of reference which you accept elsewhere the descriptions depend on.
If a complete description of something in general depends on factors A and B but you leave out B in your specific examples then you are going to get inconsistent results. The A factor might be the same in both examples but the B factors might vary but by omitting B we leave out crucial information leading to the inconsistency. This is a logical problem rather than anything to do with special relativity.
How is it you accept this yet don't put it into practice?
We have the same scenario where you are sitting in your car, but this time the lights change in sequential order and the light reaches you in that sequence; this physical scenario is also true in the physical world.
Here we have applied a more general qualifying statement, making the statement sufficiently detailed, because the relevant reference frames are just descriptions of the physical world.
Again, what we have is a single physical process which produces the same output from a different ordering of the same inputs, where the physicality of the ordering, as described by the reference frames, is immaterial. This implies that the single physical process operates in two different ways, in the skull of the observer.0 -
Again, two partial descriptions of a physical system both with crucial information left out. This crucial information is necessary in order to explain why different observers may observe different time-orderings despite it being the same physical system observed.Again, what we have is a single physical process which produces the same output from a different ordering of the same inputs, where the physicality of the ordering, as described by the reference frames, is immaterial. This implies that the single physical process operates in two different ways, in the skull of the observer.
Earlier I gave an example of how this sort of thing might come. I did this without recourse to the Lorentz transformation or anything like that. Citrus burst did likewise. You accepted this. But it could not be done without stating the way the different observers were moving with respect to the system under observation.0 -
Not according to the relativity I know.According to relativity it should.
Yes, but importantly, the skull/brain/platfom is constantly moving according to S' but stationary according to S. Or however you choose to set up the system.The brain is in the skull of the observer on the platform; the location on the platform is described by both S and S'.
This is a poor choice in words I think. Leaves a little too much ambiguity, I think. Would seem to suggest something happens when things occur simultaneously. Perhaps interval would be a better word?Ordered experience is where you see one light flash first and then the other, unordered is where there is no ordering of the light flashes, they occur together.I would agree with that, but it doesn't represent the issue.
Well its a relativistic, albeit, simplified thought experiment, showing how two observers might disagree between the time interval between two events due to their relative position.
I do agree that it doesn't represent the issue, not yet any way, I haven't gotten that far. I wanted to highlight how a time interval can be relativistic even in one reference frame. I put a few constraints on it, kept everything at rest, ie allowed time to move but kept all distances constant, but still managed to show it.
Do you understand? I might draw a picture.
I would expect to see both turn green at the same time.There are two traffic lights, either side; you are located equidistant from both lights; the lights turn green in the given order, one first then the other; the light from each green light reaches your retinae in that order; what experience would you expect to have?0 -
We don't need to explain why different observers may observe different time orderings, we simply need to acknowledge that they disagree over the order in which the stimuli enter the physical system that is the brain.Again, two partial descriptions of a physical system both with crucial information left out. This crucial information is necessary in order to explain why different observers may observe different time-orderings despite it being the same physical system observed.
Earlier I gave an example of how this sort of thing might come. I did this without recourse to the Lorentz transformation or anything like that. Citrus burst did likewise. You accepted this. But it could not be done without stating the way the different observers were moving with respect to the system under observation.
We only need to know that we are dealing with a single physical system, with different orderings of input which result in the same output; implying that the physical system, that is the brain, physically functions in two different ways in the skull of the observer.0 -
Well that is what we are exploring here.citrus burst wrote: »Not according to the relativity I know.
The contention is that the physical processes of the brain appear to behave in two different ways, in the same location. How that brain is labeled with respect to an imaginary set of co-ordinates is immaterial, because the artificial labeling shouldn't affect the underlying physical process.citrus burst wrote: »Yes, but importantly, the skull/brain/platfom is constantly moving according to S' but stationary according to S. Or however you choose to set up the system.
I'm not sure how it suggests that something happens when things occur simultaneously.citrus burst wrote: »This is a poor choice in words I think. Leaves a little too much ambiguity, I think. Would seem to suggest something happens when things occur simultaneously. Perhaps interval would be a better word?
An unordered experience is where two things, for want of a better word, are experienced non-sequentially; the label "first" cannot be applied to either object of experience, just as "second" can't be. The experiences occur together.
An ordered experience is where two things are experienced sequentially; one thing is experienced first while the other thing is experienced second. The experiences don't occur together, but in a particular order.
I do understand, but as mentioned, it doesn't represent the issue.citrus burst wrote: »Well its a relativistic, albeit, simplified thought experiment, showing how two observers might disagree between the time interval between two events due to their relative position.
I do agree that it doesn't represent the issue, not yet any way, I haven't gotten that far. I wanted to highlight how a time interval can be relativistic even in one reference frame. I put a few constraints on it, kept everything at rest, ie allowed time to move but kept all distances constant, but still managed to show it.
Do you understand? I might draw a picture.
Now, imagine you are sitting in your car and the lights don't flash sequentially, as in the previous example; they flash together; the light reaches you non-sequentially; what experience would you expect to have?citrus burst wrote: »I would expect to see both turn green at the same time.0 -
I know you don't believe me but trust me that force yourself to specify the frame of reference whenever time-ordering/simultaneity is mentioned then the apparent inconsistency either goes away or the the situation is exposed as meaningless in the first place.We don't need to explain why different observers may observe different time orderings, we simply need to acknowledge that they disagree over the order in which the stimuli enter the physical system that is the brain.
We only need to know that we are dealing with a single physical system, with different orderings of input which result in the same output; implying that the physical system, that is the brain, physically functions in two different ways in the skull of the observer.
Don't believe me? Go ahead and prove me wrong by describing the situation with frames of reference described.0 -
We have a single physical process, the production of experience by the brain. The brain is in a single physical location, in the observers skull on the platform.I know you don't believe me but trust me that force yourself to specify the frame of reference whenever time-ordering/simultaneity is mentioned then the apparent inconsistency either goes away or the the situation is exposed as meaningless in the first place.
Don't believe me? Go ahead and prove me wrong by describing the situation with frames of reference described.
Reference frame S says that the inputs into the process occurs non-sequentially or together; the reference frame S' says that the inputs into the process occurs in a different order, that is, sequentially or not together. Both reference frames say that the output of the physical process will be the same.
So, we have a single physical process with two different inputs leading to the same output, as described by the relevant reference frames; this implies that the physical process operates in two different ways in its single, physical location.
The physicality of the ordering, as described by the reference frames, appears to be irrelevant, because the brain of the observer on the train will process the non-physically ordered stimuli to produce an ordered experience. What is important is that there is disagreement over the ordering of the inputs, but both are supposedly correct; this, again, means we have a differing order of inputs leading to the same output from a physical process, implying that the process physically functions in two different ways.0 -
Thank you but you didn't say how the frames S and S' are moving either relative to each other or relative to the platform.We have a single physical process, the production of experience by the brain. The brain is in a single physical location, in the observers skull on the platform.
Reference frame S says that the inputs into the process occurs non-sequentially or together; the reference frame S' says that the input into the process occurs in a different order, that is, sequentially or not together. Both reference frames say that the output of the physical process will be the same.
So, we have a single physical process with two different inputs leading to the same output, as described by the relevant reference frames; this implies that the physical process operates in two different ways in its single physical location.0 -
The reference frames aren't moving relative to each other or the platform, because the reference frames are mathematical constructs, which don't exist a priori in nature; only physical objects can move relative to other physical objects.Thank you but you didn't say how the frames S and S' are moving either relative to each other or relative to the platform.
The brain, of the observer on the platform, is at rest relative to the platform and in motion relative to the train and the observer on the train; the observer on the platform is at rest relative to the sources of light, while the observer on the train is moving relative to them. This is why they disagree over the order of the inputs into the physical process.
The single physical process in question is the brain of the observer on the platform, and how it produces experiences; this, as above is at rest relative to the platform and in motion relative to the train.
The inputs into this single physical process occur in two different orders, while the system/process is at rest relative to the platform and in motion relative to the train; according to the descriptions given by the relevant reference frames.
EDIT:
So, when the single, physical process is in motion relative to the train and at rest relative to the platform, it produces an unordered, or non-sequential experience from unordered, or non-sequential input. This is according to the reference frame S.
While the single, physical process is in motion relative to the train and at rest relative to the platform, it produces an unordered, or non-sequential experience from sequential, or ordered, input. This is according to the reference frame S'.
So, the physical process, in it's single, physical location - in motion wrt the train and at rest wrt the platform - will produce the same output from two different orders of input; this implies that the physical process functions in two different ways in its single, physical location.0 -
Advertisement
-
The answer is that if you accept that time ordering is frame dependent (as you do) you must also accept that it applies to the time ordering of events within the brain.EDIT:
So, when the single, physical process is in motion relative to the train and at rest relative to the platform, it produces an unordered, or non-sequential experience from unordered, or non-sequential input. This is according to the reference frame S.
While the single, physical process is in motion relative to the train and at rest relative to the platform, it produces an unordered, or non-sequential experience from sequential, or ordered, input. This is according to the reference frame S'.
Frame S:
Inputs strike simultaneously with respect to that frame. A sequence of events occurs which leads to the experience of simultaneity in the subject.
Frame S':
Inputs strike non-simultaneously with respect to that frame. A sequence of events happens (the timing of which will not be the same as in S) such that the experience of simultaneity in the subject occurs.
Essentially we have one set of inputs hitting one physical system producing one output. It is only the measurement of the timing of events (including those happening in the brain after the inputs strike) that differ and we both agree already that the timing of events is frame dependent.0 -
If you have a single physical process where different orders of input lead to the same output, it implies that the physical process behaves in two different ways.The answer is that if you accept that time ordering is frame dependent (as you do) you must also accept that it applies to the time ordering of events within the brain.
Frame S:
Inputs strike simultaneously with respect to that frame. A sequence of events occurs which leads to the experience of simultaneity in the subject.
Frame S':
Inputs strike non-simultaneously with respect to that frame. A sequence of events happens (the timing of which will not be the same as in S) such that the experience of simultaneity in the subject occurs.
Essentially we have one set of inputs hitting one physical system producing one output. It is only the measurement of the timing of events (including those happening in the brain after the inputs strike) that differ and we both agree already that the timing of events is frame dependent.
If it is only the measurements of the timing of the events which differ, this implies that the ordering of the events is the same; one flash doesn't occur before the other, it's just the clock time attributed to the flashes which is different; and the clock times attributed to the physical process. This means that [at least] one of the observers is potentially incorrect about the ordering of events.0 -
Well that is one way of thinking about it but I would suggest to you that it is not the best way.If you have a single physical process where different orders of input lead to the same output, it implies that the physical process behaves in two different ways.
If it is only the measurements of the timing of the events which differ, this implies that the ordering of the events is the same; one flash doesn't occur before the other, it's just the clock time attributed to the flashes which is different; and the clock times attributed to the physical process. This means that [at least] one of the observers is potentially incorrect about the ordering of events.
Another way of thinking about it is that the system behaves in one way according to the laws of physics whatever they happen to be. However in order to know about the system we must make measurements and whatever measurements we make, in general, our instruments will be in some form of motion with respect to the system. Depending on this motion, we will get a different set of for the position and timing of events in the system. But varying measurements does not imply the system behaving differently. What it just means is that we have to be more sophisticated in our determination of what those measurements actually mean.0 -
It's not so much a way of thinking about it, it is a conclusion which is being drawn.Well that is one way of thinking about it but I would suggest to you that it is not the best way.
Being more sophisticated about the determination of what the measurements mean, isn't so much a conclusion as it is a guiding principle which should be followed from the outset.Another way of thinking about it is that the system behaves in one way according to the laws of physics whatever they happen to be. However in order to know about the system we must make measurements and whatever measurements we make, in general, our instruments will be in some form of motion with respect to the system. Depending on this motion, we will get a different set of for the position and timing of events in the system. But varying measurements does not imply the system behaving differently. What it just means is that we have to be more sophisticated in our determination of what those measurements actually mean.
The conclusion drawn above is drawn from those measurements (or the concepts of those measurements) and the contention is that the conclusion is representative of what those measurements mean; or perhaps, that the meaning of those measurements is captured in the conclusion; namely that, either the same physical process operates in two different ways, or that [at least] one of the observers is mistaken about the ordering of events.
Investigating the nature of "time" measurements is a subject I think is quite interesting though; namely, how it is that a clock measures a physical property called time.0 -
But what of the situation such as where you have two simultaneous flashes hitting opposite ends of a moving train which are simultaneous when measured from the platform.The conclusion drawn above is drawn from those measurements (or the concepts of those measurements) and the contention is that the conclusion is representative of what those measurements mean; or perhaps, that the meaning of those measurements is captured in the conclusion; namely that, either the same physical process operates in two different ways, or that [at least] one of the observers is mistaken about the ordering of events.
On the train itself (which has blacked out windows) the light is deflected so that it is directed towards a central point where the timing is recorded by an observer.
I won't go into the details but we have already established that the the signals arrive at the central point non-simultaneously as seen by the observer on the train.
Yet, and here is the crux, an observer on the train traveling in constant motion should not be able to tell the velocity or indeed whether it is moving or not relative to anything without some reference to the outside world. He therefore has no way of knowing whether those outside flashes were produced simultaneously on the platform to the a moving train or non-simultaneously with the train stationary on the platform. All he sees are flashes going off at either end the train and the light arriving at the central point non-simultaneously.
If you hold the view that the timing of flashes as observed by an outside observer on the platform is the "valid" one, then we have a situation where the inside observer - the one on the train has no way of determining valid from invalid. If the train is stationary wrt the platform then the timing on the train will match that on the platform and be "valid". If the train is moving then the timings won't match and they will be "invalid".
Since there's no possible experiment he can do to determine the speed of the train relative to anything, theres no way of determining valid from invalid and therefore we must abandon the notion of a valid or invalid timing. We have to treat every measurement as equally valid.0 -
0
-
If you cannot determine whether a measurement is valid or not, I'm not sure the solution is to treat it as valid; and treating every measurement as valid doesn't do away with the notion of valid and invalid, it does away with the notion of invalid.But what of the situation such as where you have two simultaneous flashes hitting opposite ends of a moving train which are simultaneous when measured from the platform.
On the train itself (which has blacked out windows) the light is deflected so that it is directed towards a central point where the timing is recorded by an observer.
I won't go into the details but we have already established that the the signals arrive at the central point non-simultaneously as seen by the observer on the train.
Yet, and here is the crux, an observer on the train traveling in constant motion should not be able to tell the velocity or indeed whether it is moving or not relative to anything without some reference to the outside world. He therefore has no way of knowing whether those outside flashes were produced simultaneously on the platform to the a moving train or non-simultaneously with the train stationary on the platform. All he sees are flashes going off at either end the train and the light arriving at the central point non-simultaneously.
If you hold the view that the timing of flashes as observed by an outside observer on the platform is the "valid" one, then we have a situation where the inside observer - the one on the train has no way of determining valid from invalid. If the train is stationary wrt the platform then the timing on the train will match that on the platform and be "valid". If the train is moving then the timings won't match and they will be "invalid".
Since there's no possible experiment he can do to determine the speed of the train relative to anything, theres no way of determining valid from invalid and therefore we must abandon the notion of a valid or invalid timing. We have to treat every measurement as equally valid.
I think the point remains, that if you have a physical process which produces the same output from two different orders of input, then it suggests that the physical process behaves in two different ways.
If it is only the readings on a clock which differs, and not the ordering of the input, it suggests that there is a single ordering of events which is correct, but that the issue lies in the readings on the clocks.0 -
I think this is the first time you've addressed this particular point.Nope. I have corrected you on this before. The above statement is only true in the reference frame that labels the observer as stationary.
What do you mean by "the above statement is only true in the reference frame that labels the observer as stationary."?
I am asking because the brian doesn't process stimuli "in" a reference frame, it processes them in the physical world, where the observer is either at rest or in motion relative to other physical things.0 -
I think this is the first time you've addressed this particular point.
What do you mean by "the above statement is only true in the reference frame that labels the observer as stationary."?
I am asking because the brian doesn't process stimuli "in" a reference frame, it processes them in the physical world, where the observer is either at rest or in motion relative to other physical things.
I have addressed this point previously.Morbert wrote:For a given reference frame X, an observer that X labels as stationary will experience events that X labels simultaneous as simultaneous. An observer that X labels as moving will experience events that X labels simultaneous as non-simultaneous.0 -
Advertisement
-
I have addressed this point previously.
I think you might be conflating the idea of what an observer will calculate with the experience their brain will produce; for a given reference frame X, an observer that X labels as stationary but not equidistant between two events, their brain will produce an ordered experience of events that X labels simultaneous.Morbert wrote:For a given reference frame X, an observer that X labels as stationary will experience events that X labels simultaneous as simultaneous. An observer that X labels as moving will experience events that X labels simultaneous as non-simultaneous.
Also, X doesn't label the retinae striking events, of the observer on the train, as simultaneous.
We can also say that:
For a given reference frame Y, an observer that Y labels as moving will experience events that Y labels non-simultaneous as simultaneous. An observer that Y labels as at rest will experience events that Y labels non-simultaneous as non-simultaneous.
This is just a re-statement of the issue in hand in more general, or vague terms; the same reasoning applies though. The ordering of events is still not physical and the brain of the observer on the train will still process the stimuli; we still have a single, physical process with two different orders of input, implying that the process physically works in two different ways.0
Advertisement