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Question on Lorentz transforms and relativity of simultaneity
Comments
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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.
No.Also, X doesn't label the retinae striking events, of the observer on the train, as simultaneous.
I don't know what this sentence refers to. X is any given reference frame.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.
No. We have one set of physical events with various coordinate labels reflecting the various possible apparatus that can be used to measure the physical events.0 -
Apologies, I was disputing the wrong partNo.
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I don't know what this sentence refers to. X is any given reference frame.
I was disputing this when all I was really doing was saying that that observer will experience events which X labels as non-simultaneous as non-simultaneous.For a given reference frame X, an observer that X labels as stationary will experience events that X labels simultaneous as simultaneous.
This is where the issue lies, however:An observer that X labels as moving will experience events that X labels simultaneous as non-simultaneous.
an observer that X labels as moving will experience events that X labels as non-simultaneous as either simultaneous or non-simultaneous; where the events in question are the retinae striking events, or the input into the physical process.
To clarify this we can have a third observer who is moving relative to Albert and Henry in the direction of one of the flashes. Albert will have a simultaneous experience of the flashes while the third observer won't.
We can avoid this talking in generalities though, simply by asking whether, according to the relevant reference frames, the brain begins processing the stimuli when they are received; that is, does the processing of the stimuli begin when the photons strike the retinae, according to S'? If so, then it demonstrates that the body will processes the stimuli, regardless of the physicality of the ordering.
But we use those co-ordinates to make statements about the order of input into a physical process; so while we have a single, physical process and a single set of events, we have two different orders of input into that physcial process, which result in the same output; suggesting that the physical process operates in two different ways.No. We have one set of physical events with various coordinate labels reflecting the various possible apparatus that can be used to measure the physical events.
If there isn't two different orders of input, into the physical process, if the disagreement over the ordering is attributable to different readings on the time apparatus, that implies that there is a single ordering of input and that there is a diconnect between the orderings of events and the readings from the time apparatus.
Out of interest, you've mentioned that there is an underlying physical ordering, is there ever a single reference frame which corresponds with that underling physical ordering?0 -
I want to have another bash at dealing with the the idea that if the measurements differ about the ordering of events then at a) least one observer must be mistaken or the b) same physical process operates in two different ways.
Roosh, I would be grateful if you could read it to the end before commenting.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.
Consider the following (we have discussed similar scenarios already):
We have an observer on the platform, 01
We have a moving train with an observer, O2, on board in the mid-point.
When the train is in such a position that O1 and O2 are next to each other, O1 observes simultaneous lightning strikes hitting opposite ends of the train. They produce a flash as they hit the train.
The train is made of glass, so the observer on the train O2 has no problem seeing the flash as they hit the train.
We have already established that O2 will see those two strikes as non-simultaneous so we need not explain that.
That is the scenario. We have two observers with different measurements. Now lets examine the contention that one of the observers is correct and one is mistaken.
a) The contention that one of the observers is mistaken.
The most obvious answer is that O1 on the platform is correct. As the lightning strikes, O1 is mid-way between the two lightning strikes. Since the speed of light is constant, the light will take the same length of time to reach O1 from the two flashes. Therefore the flashes are genuinely simultaneous.
If the contention is correct, that makes the measurement taken by O2 on the train incorrect, right?
Well maybe not. O2 is also at the mid point of the train and the flashes occur at either end. Even though the train is moving with respect to the platform, the speed of light is still the same relative to the observer on the train, O2. Therefore, the light takes the same length of time to reach the mid-point of the train from the ends. If the light arrives at the mid point non-simultaneously, the lightning flashes must have genuinely occurred non-simultaneously at either end of the train as observed by O2.
This means that O2 must also be correct.
If we still insist that either O1 is correct or O2 is correct but not both, how are we to determine which? If you strip away the train and the platform and just deal with the two observers and the two light flash events, you can see that the setup is essentially symmetric. Whilst in the example we have taken O1 to be stationary and O2 moving we can swap this around to have O2 moving and O1 stationary. We still get the result that if the flashes are simultaneous for O1 they are non-simultaneous for O2, and likewise if they are simultaneous for O2 they are non-simultaneous for O1.
What this means for both observers, the measurements are equally valid. There is no conceivable way of showing one is more valid that the other.
b) The contention that the same physical process operates in two different ways:
If the observers later meet and compare notes it does appear to each of them that different things have happened, but that doesn't mean that it has.
Well, there's only one physical system here. The train only passes by once. The are two lightning flashes at either end of the train but each flash only occurs once. The light only has one chance to reach each of the observers from the two lightning flashes.
This means that the system is operating in one way. The only thing that varies is that the observers are moving relative to each other and these observers make different measurements of the same physical system but neither is more valid than the other.0 -
No problem dlouth, I always read posts fully before replying; when I reply to individual segments, it's because I find it to be a bit clearer for dealing with specific issues.I want to have another bash at dealing with the the idea that if the measurements differ about the ordering of events then at a) least one observer must be mistaken or the b) same physical process operates in two different ways.
Roosh, I would be grateful if you could read it to the end before commenting.
The thing is, we can agree with all of the above and say that it makes sense; the issue is that we also have some other issues to consider, namely the issues we have been discussing, which appear to be equally valid; particularly if we look at it in the reverse order, from how you have laid out the post.Consider the following (we have discussed similar scenarios already):
We have an observer on the platform, 01
We have a moving train with an observer, O2, on board in the mid-point.
When the train is in such a position that O1 and O2 are next to each other, O1 observes simultaneous lightning strikes hitting opposite ends of the train. They produce a flash as they hit the train.
The train is made of glass, so the observer on the train O2 has no problem seeing the flash as they hit the train.
We have already established that O2 will see those two strikes as non-simultaneous so we need not explain that.
That is the scenario. We have two observers with different measurements. Now lets examine the contention that one of the observers is correct and one is mistaken.
a) The contention that one of the observers is mistaken.
The most obvious answer is that O1 on the platform is correct. As the lightning strikes, O1 is mid-way between the two lightning strikes. Since the speed of light is constant, the light will take the same length of time to reach O1 from the two flashes. Therefore the flashes are genuinely simultaneous.
If the contention is correct, that makes the measurement taken by O2 on the train incorrect, right?
Well maybe not. O2 is also at the mid point of the train and the flashes occur at either end. Even though the train is moving with respect to the platform, the speed of light is still the same relative to the observer on the train, O2. Therefore, the light takes the same length of time to reach the mid-point of the train from the ends. If the light arrives at the mid point non-simultaneously, the lightning flashes must have genuinely occurred non-simultaneously at either end of the train as observed by O2.
This means that O2 must also be correct.
If we still insist that either O1 is correct or O2 is correct but not both, how are we to determine which? If you strip away the train and the platform and just deal with the two observers and the two light flash events, you can see that the setup is essentially symmetric. Whilst in the example we have taken O1 to be stationary and O2 moving we can swap this around to have O2 moving and O1 stationary. We still get the result that if the flashes are simultaneous for O1 they are non-simultaneous for O2, and likewise if they are simultaneous for O2 they are non-simultaneous for O1.
What this means for both observers, the measurements are equally valid. There is no conceivable way of showing one is more valid that the other.
b) The contention that the same physical process operates in two different ways:
If the observers later meet and compare notes it does appear to each of them that different things have happened, but that doesn't mean that it has.
Well, there's only one physical system here. The train only passes by once. The are two lightning flashes at either end of the train but each flash only occurs once. The light only has one chance to reach each of the observers from the two lightning flashes.
This means that the system is operating in one way. The only thing that varies is that the observers are moving relative to each other and these observers make different measurements of the same physical system but neither is more valid than the other.
Two-ways
The two observers reconvene to compare notes; observer 02 says that the physical input went into the process in the order of left first, then right (for arguments sake); he maintains that the left side of the process physically began operating before the right side; that is, there was a sequential order to the operating of the physical process.
Observer 02 disagrees, he says that there was no sequential ordering of the physical input into the system; he says that the left side didn't physically start operating before the right side, he says they started together.
If a physical process, physically starts operating on one side before it physically starts operating on another, but it also starts operating physically such that there is no sequential ordering to the process, this implies that the physical process operates in two different ways. In general this wouldn't be a problem, there is nothing wrong with physical processes operating in two different ways. However, if we say that the flashes only occur once, that the input into the system only occurs once, then it implies that the physical process operates in two different ways, at once.
Do you think that that is a fair enough deduction, in and of itself?
Right or wrong?
If that is deemed to be a fair deduction, then I think we can agree that it represents an unpalatable paradox, for which a resolution is required; unless the contention is that there is no problem with a single physical process physically operating in two different ways, at once.
The solution appears to be to say that there is a single physical process which operates in a single physical way; that the disagreement lies in the clock readings each observer attributes to the inputs into the process and the physical operating of the process - actually, the observers agree over the time readings don't they, they just disagree over the synchronisation of the clocks.
So, if we take the idea that a different order of inputs into a physical process, leading to the same outcome, implies that the single process operates in two different ways, and decide that this cannot be the case, then we must agree that there is a single order to the inputs which represents the correct ordering - or we could ad an ad hoc explanation, which I don't think is palatable either.
If the disagreement over the ordering of inputs is deduced from an issue pertaining to the clocks, but we say that there must be a single ordering to the physical inputs into the process - otherwise we arrive at the conclusion above - then we must agree that there is a disconnect between what the clocks tell us about the ordering of the events, and the correct ordering of events.
We're not necessarily saying that either is right or wrong, just that there is an issue with deducing the order of events from clocks; because it is conceivable that both are wrong.0 -
Yes on the face of it, if the two observers compare notes, it would appear to them that the system is operating in two ways at once. Would they be correct though?No problem dlouth, I always read posts fully before replying; when I reply to individual segments, it's because I find it to be a bit clearer for dealing with specific issues.
The thing is, we can agree with all of the above and say that it makes sense; the issue is that we also have some other issues to consider, namely the issues we have been discussing, which appear to be equally valid; particularly if we look at it in the reverse order, from how you have laid out the post.
Two-ways
The two observers reconvene to compare notes; observer 02 says that the physical input went into the process in the order of left first, then right (for arguments sake); he maintains that the left side of the process physically began operating before the right side; that is, there was a sequential order to the operating of the physical process.
Observer 02 disagrees, he says that there was no sequential ordering of the physical input into the system; he says that the left side didn't physically start operating before the right side, he says they started together.
If a physical process, physically starts operating on one side before it physically starts operating on another, but it also starts operating physically such that there is no sequential ordering to the process, this implies that the physical process operates in two different ways. In general this wouldn't be a problem, there is nothing wrong with physical processes operating in two different ways. However, if we say that the flashes only occur once, that the input into the system only occurs once, then it implies that the physical process operates in two different ways, at once.
Do you think that that is a fair enough deduction, in and of itself?
Yes, it appears to be a paradox on the face of it.Right or wrong?
If that is deemed to be a fair deduction, then I think we can agree that it represents an unpalatable paradox, for which a resolution is required; unless the contention is that there is no problem with a single physical process physically operating in two different ways, at once.
Yes I agree.The solution appears to be to say that there is a single physical process which operates in a single physical way;
Now hold on here a second. They don't need to synchronise clocks. They just need to determine whether the light from the flashes reaches their respective central points simultaneously or not.that the disagreement lies in the clock readings each observer attributes to the inputs into the process and the physical operating of the process - actually, the observers agree over the time readings don't they, they just disagree over the synchronisation of the clocks.
Well no. I have described the system in full in my earlier post. Yes we have one set of inputs, but the two observers differ on the order the inputs came in based on their measurements. The measurements say whether or not the light reaches the respective mid-points simultaneously but because the speed of light is constant, they also determine whether or not the lightning flashes occurred simultaneously. So the observers differ on the the order of the actual inputs.So, if we take the idea that a different order of inputs into a physical process, leading to the same outcome, implies that the single process operates in two different ways, and decide that this cannot be the case, then we must agree that there is a single order to the inputs which represents the correct ordering - or we could ad an ad hoc explanation, which I don't think is palatable either.
This is about the clocks but we don't actually need clocks as such here.If the disagreement over the ordering of inputs is deduced from an issue pertaining to the clocks, but we say that there must be a single ordering to the physical inputs into the process - otherwise we arrive at the conclusion above - then we must agree that there is a disconnect between what the clocks tell us about the ordering of the events, and the correct ordering of events.
Both could be wrong, or one of them could be right. Looking back at the system as described, can you think of a way of determining which is right or wrong? Is it possible, do you think, that in a sense that all observers are likely to be wrong, or more precisely, that each of the observers is only partly right? If we can't say at all whether one or other or any is right or wrong even in principle, what does that mean to you? I will give you my answer later but I'd like to hear yours first.We're not necessarily saying that either is right or wrong, just that there is an issue with deducing the order of events from clocks; because it is conceivable that both are wrong.0 -
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We can avoid this talking in generalities though, simply by asking whether, according to the relevant reference frames, the brain begins processing the stimuli when they are received; that is, does the processing of the stimuli begin when the photons strike the retinae, according to S'? If so, then it demonstrates that the body will processes the stimuli, regardless of the physicality of the ordering.
The causal structure is agreed upon by all observers, since it is physical. So observers agree that the signals reach the retinas, and propagates through the brain, causing neurons to fire that generate the experience of being blinded at the same time.
According to Relativity, however, this does not reflect any physical ordering of the poles flashing or of the retinas being blinded, because events that are causally unconnected have no intrinsic ordering. Instead, the simultaneity experienced is a reflection of the apparatus used (the brain). Another apparatus moving relative to the first, would produce a different experience. Relativity states that neither is more correct than the other, because the difference is due to the fundamental geometry of spacetime.
While you might not like some of the metaphysical implications of a 4D block universe (that is being hashed out in other threads), the purpose of this thread was to highlight an inconsistency with the formalism of relativity. There is categorically no inconsistency.But we use those co-ordinates to make statements about the order of input into a physical process; so while we have a single, physical process and a single set of events, we have two different orders of input into that physcial process, which result in the same output; suggesting that the physical process operates in two different ways.
If there isn't two different orders of input, into the physical process, if the disagreement over the ordering is attributable to different readings on the time apparatus, that implies that there is a single ordering of input and that there is a diconnect between the orderings of events and the readings from the time apparatus.
An analogy: Take a blank piece of paper and draw some dots on it. This is the physical world. The dots are events. Now lets say some observers want to measure this physical world. They bring along their own transparent sheets with their own grids, and place them on top of the paper. One observer says two dots lie on the same grid line. Another observer might say the dots lie on different grid lines. One observer might say a dot lies 4 grid points to the left of another. Another observer might say it is 3 grid points. All of these statements about the dots relations to one another are reflections of how observer measure the physical world, rather than the physical world itself. No grid is more correct than another (provided they are treated consistently). They are all just different.
So instead of using the grids to make direct statements about what is physically real, they use the grids to unearth what relations and statements are "covariant" or "the same for all observers". This practise is formulated into a single principle and physical laws and relations are constructed from it.Out of interest, you've mentioned that there is an underlying physical ordering, is there ever a single reference frame which corresponds with that underling physical ordering?
All reference frames obey the underlying physical ordering. I.e. All frames agree with the ordering of causally connected events. No reference frame, for example, will have you responding to this post before I send it.0 -
I would say that they can't both be correct; a single physical system can't physically operate in two different ways at once; unless there is some ad hoc and exotic explanation.Yes on the face of it, if the two observers compare notes, it would appear to them that the system is operating in two ways at once. Would they be correct though?
Yes, it appears to be a paradox on the face of it.
Having a single pyhsical system which physically operates in two different ways at once, does seem to be somewhat paradoxical.
But you would also agree that it appears that what is being implied is that a single physical system behaves in two different ways at once?Yes I agree
Clock synchronisation seems to be necessary to determine the order in which the physical input enters the process; both observers say that the experience is non-sequential, but they disagree over the order of the input into the physical process.Now hold on here a second. They don't need to synchronise clocks. They just need to determine whether the light from the flashes reaches their respective central points simultaneously or not.
Which is the issue; they disagree over the ordering of inputs into the physical system, but both of them are supposedly correct; they disagree over the order in which the physical process begins; one says that the physical process begins on one side before the other, but the other says that both sides of the process begin together. This suggests that a single physical process operates in two different ways at once.Well no. I have described the system in full in my earlier post. Yes we have one set of inputs, but the two observers differ on the order the inputs came in based on their measurements. The measurements say whether or not the light reaches the respective mid-points simultaneously but because the speed of light is constant, they also determine whether or not the lightning flashes occurred simultaneously. So the observers differ on the the order of the actual inputs.This is about the clocks but we don't actually need clocks as such here.
To be honest, I haven't given it much thought; the thought simply occurred to me that an observer should have two different, discordant experiences of the same event; that was the line of reasoning that was followed which has lead to the opposite side of the same coin, namely that, if an observer doesn't have discordant experiences of the same event, then the implication is that the single physical process, that is the generation of experience by the brain, must be operating in two different ways at once. Which seems to be paradoxical.Both could be wrong, or one of them could be right. Looking back at the system as described, can you think of a way of determining which is right or wrong? Is it possible, do you think, that in a sense that all observers are likely to be wrong, or more precisely, that each of the observers is only partly right? If we can't say at all whether one or other or any is right or wrong even in principle, what does that mean to you? I will give you my answer later but I'd like to hear yours first.
I think that the line of reasoning can be extended to inanimate systems, or processes also, the simple system you described earlier in the thread.0 -
Observers agree on the local clock readings for all the events in question, don't they; or, perhaps, it's that they agree on the clock readings for clocks at rest relative to the observer [on the platform]? They disagree, however, over what this implies, don't they? The observer moving relative to the platform says that the signals arrive at the retinas in sequential order, while the observer says they arrive non-sequentially; both agree that the signals result in an unordered experience for the observer on the platform. In other words, one observer says that physical inputs enter a process in sequental order, such the the process starts physically operating in sequential order; that is, one side physically starts operating before the other; the other observer disagrees, and says that there is no sequential ordering to how the process physically operates, he says that both sides start operating together. Both observers are supposedly correct.The causal structure is agreed upon by all observers, since it is physical. So observers agree that the signals reach the retinas, and propagates through the brain, causing neurons to fire that generate the experience of being blinded at the same time.
According to Relativity, however, this does not reflect any physical ordering of the poles flashing or of the retinas being blinded, because events that are causally unconnected have no intrinsic ordering. Instead, the simultaneity experienced is a reflection of the apparatus used (the brain). Another apparatus moving relative to the first, would produce a different experience. Relativity states that neither is more correct than the other, because the difference is due to the fundamental geometry of spacetime.
While you might not like some of the metaphysical implications of a 4D block universe (that is being hashed out in other threads), the purpose of this thread was to highlight an inconsistency with the formalism of relativity. There is categorically no inconsistency.
So we have a scenario where sequential ordering of physical inputs into a system, leads to the different sides of the process physically starting in sequential order; this leads to the physical process producing an unordered output.
We also have the scenario where non-sequential ordering of physical inputs, into the system, leads to the different sides of the process starting non-sequentially, or starting together; this also leads to an unordered output being produced by the system.
This would seem to imply that we have a single physical system/process which physically operates in two different ways, at once.
One thing which is not the same for all observers is the ordering of the events; in our case, the ordering of physical inputs into a physical process, which is what gives rise to the issue.An analogy: Take a blank piece of paper and draw some dots on it. This is the physical world. The dots are events. Now lets say some observers want to measure this physical world. They bring along their own transparent sheets with their own grids, and place them on top of the paper. One observer says two dots lie on the same grid line. Another observer might say the dots lie on different grid lines. One observer might say a dot lies 4 grid points to the left of another. Another observer might say it is 3 grid points. All of these statements about the dots relations to one another are reflections of how observer measure the physical world, rather than the physical world itself. No grid is more correct than another (provided they are treated consistently). They are all just different.
So instead of using the grids to make direct statements about what is physically real, they use the grids to unearth what relations and statements are "covariant" or "the same for all observers". This practise is formulated into a single principle and physical laws and relations are constructed from it.
We seem to have a single physical process which produces the same outcome from two different orders of input; this would suggest that a single process physically operates in two different ways at once.
Ah, OK, I had something else in mind.All reference frames obey the underlying physical ordering. I.e. All frames agree with the ordering of causally connected events. No reference frame, for example, will have you responding to this post before I send it.0 -
Observers agree on the local clock readings for all the events in question, don't they; or, perhaps, it's that they agree on the clock readings for clocks at rest relative to the observer [on the platform]? They disagree, however, over what this implies, don't they? The observer moving relative to the platform says that the signals arrive at the retinas in sequential order, while the observer says they arrive non-sequentially; both agree that the signals result in an unordered experience for the observer on the platform. In other words, one observer says that physical inputs enter a process in sequental order, such the the process starts physically operating in sequential order; that is, one side physically starts operating before the other; the other observer disagrees, and says that there is no sequential ordering to how the process physically operates, he says that both sides start operating together. Both observers are supposedly correct.
So we have a scenario where sequential ordering of physical inputs into a system, leads to the different sides of the process physically starting in sequential order; this leads to the physical process producing an unordered output.
We also have the scenario where non-sequential ordering of physical inputs, into the system, leads to the different sides of the process starting non-sequentially, or starting together; this also leads to an unordered output being produced by the system.
This would seem to imply that we have a single physical system/process which physically operates in two different ways, at once.
It does not imply any such thing. Instead, we have a different coordinate descriptions of a single physical system.One thing which is not the same for all observers is the ordering of the events; in our case, the ordering of physical inputs into a physical process, which is what gives rise to the issue.
We seem to have a single physical process which produces the same outcome from two different orders of input; this would suggest that a single process physically operates in two different ways at once.
No. Again, see my analogy. We have one set of events, but multiple coordinate systems we can place over the events to offer multiple descriptions.0 -
Yes, we could say that the system operates in two different ways at once and the way it operates depends in some way on the observer's motion, but I think you will agree that there's something unsatisfactory about that description.But you would also agree that it appears that what is being implied is that a single physical system behaves in two different ways at once?
You could have a clock for each observer and both of them record the time in which the flashes arrive, but the two clocks don't need to be synchronized with each other. I don't think you really need a clock at all to determine whether the flashes were simultaneous or not. A simple logic circuit would suffice would it not?Clock synchronisation seems to be necessary to determine the order in which the physical input enters the process; both observers say that the experience is non-sequential, but they disagree over the order of the input into the physical process.
Yes it does appear to be that way. Yet, as said earlier, we are clearly describing a system that operates in a single way. What we really want, would you not agree, is an explanation that treats the system as operating in a one way but explains how certain observations will vary according to the motion of the observers?Which is the issue; they disagree over the ordering of inputs into the physical system, but both of them are supposedly correct; they disagree over the order in which the physical process begins; one says that the physical process begins on one side before the other, but the other says that both sides of the process begin together. This suggests that a single physical process operates in two different ways at once.
I think the key is to consider the simplest possible system that generates the apparent paradox. Try and resolve the paradox with the simple system and then and only then see if it can be extended to things like brains. What this simple system illustrates is that we can describe fairly straightforwardly as operating in a single way. We can show using considerations of the constancy of the speed of light that different observers will make different observations of the same system. We can also show that there's nothing special about either observer. We can regard one as stationary and the other moving or vice-versa if we wish and the fundamentals of the system stay the same.To be honest, I haven't given it much thought; the thought simply occurred to me that an observer should have two different, discordant experiences of the same event; that was the line of reasoning that was followed which has lead to the opposite side of the same coin, namely that, if an observer doesn't have discordant experiences of the same event, then the implication is that the single physical process, that is the generation of experience by the brain, must be operating in two different ways at once. Which seems to be paradoxical.
Yes, to each of them the system appears to be operating in a different way but most would agree that this is unsatisfactory and presents a paradox.
A good explanation would try to avoid this paradox which is what special relativity tries to do.
The other interpretation that one or more observers is making incorrect observations is also problematic. If we go with this line of reasoning we have to then say which is correct or incorrect. If both are incorrect, then where would you put an observer who could make the "correct" measurement? Is there a correct measurement, i.e., in the simple system described in full above, are the flashes simultaneous or not?
Again special relativity tries to resolve these questions. What it won't do, however is make the world conform to our everyday expectations of how things should happen. We still need to modify those expectations. But the simple system described earlier shows that these expectations can't be right to start with even without any knowledge of special relativity or any other theory.
Or likewise the simple system can be extended to more complicated ones. If we can show an apparent paradox with a very simple system, it is likely that this same apparent paradox is in operation with more complicated ones such as the biological ones.I think that the line of reasoning can be extended to inanimate systems, or processes also, the simple system you described earlier in the thread.0 -
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and, on the basis of those co-ordinate descriptions, relatively moving observers will disagree over how the physical process operates; they will agree over the output produced by the system, but they will disagree over how the physical system functions to produce that output.It does not imply any such thing. Instead, we have a different coordinate descriptions of a single physical system.
One observer will say that one side of the process starts physically operating before the other, while the other says that the process doesn't start physically operating in sequential order.
Both are supposedly correct, so it implies that the same physical process operates in two different ways, at once.
Is the ordering of events the same for all observers?No.
and what those co-ordinate labels do is ascribe an order to those events, implying that the order in which physical inputs go into a physical system, and the order in which a physical process starts operating, is different, but equally correct; this implies that the same physical process operates in two different ways, at once.Again, see my analogy. We have one set of events, but multiple coordinate systems we can place over the events to offer multiple descriptions.0 -
I would agree, it seems to be paraodoxical; but this is what seems to be implied from relativity.Yes, we could say that the system operates in two different ways at once and the way it operates depends in some way on the observer's motion, but I think you will agree that there's something unsatisfactory about that description.
I don't think the observers need to synchronise their clocks with each other, but the clocks located at the retinas or the detectors do need to be synchronised don't they?You could have a clock for each observer and both of them record the time in which the flashes arrive, but the two clocks don't need to be synchronized with each other. I don't think you really need a clock at all to determine whether the flashes were simultaneous or not. A simple logic circuit would suffice would it not?
Either way it still comes down to the ordering of physical inputs into a physical system, and the order in which that physical system starts operating.
Is this an observation that requires explanation? That is we don't have any experimental observations which correspond to the question in hand, partly because we can't travel at speeds high enough for the effects to be noticeable.Yes it does appear to be that way. Yet, as said earlier, we are clearly describing a system that operates in a single way. What we really want, would you not agree, is an explanation that treats the system as operating in a one way but explains how certain observations will vary according to the motion of the observers?
I know relativity makes other predictions which are partly supported by experimental observations - I don't think there is any evidence for the reciprocity of contractions that relativity predicts - but is it possible to interpret the mathematics of relativity in such a way that it doesn't lead to this apparent paradox?
We can formulate it in such a way that encompasses systems of infinitely varying degrees of complexity, from the most basic to the most complex, without needing to specify the actual set up of the system. When we say that we are dealing with a single physical process, and two different orders of input into that system, which produce the same output, that can refer to the simplest possible system or the most complex. The conclusion remains the same.I think the key is to consider the simplest possible system that generates the apparent paradox. Try and resolve the paradox with the simple system and then and only then see if it can be extended to things like brains. What this simple system illustrates is that we can describe fairly straightforwardly as operating in a single way. We can show using considerations of the constancy of the speed of light that different observers will make different observations of the same system. We can also show that there's nothing special about either observer. We can regard one as stationary and the other moving or vice-versa if we wish and the fundamentals of the system stay the same.
Yes, to each of them the system appears to be operating in a different way but most would agree that this is unsatisfactory and presents a paradox.
It's from special relativity though, that the paradox seems to arise.A good explanation would try to avoid this paradox which is what special relativity tries to do.
What if the clocks of relatively moving observers actually ticked at different rates; what if the clock of one observer moving relative to another actually ticked faster than the others clock, leading to different measurements? Only if we say that one clock is the correct clock would we imply that one of the observers is incorrect, but if we just have clocks which tick at different rates then neither observer is correct or incorrect.The other interpretation that one or more observers is making incorrect observations is also problematic. If we go with this line of reasoning we have to then say which is correct or incorrect. If both are incorrect, then where would you put an observer who could make the "correct" measurement? Is there a correct measurement, i.e., in the simple system described in full above, are the flashes simultaneous or not?
The issue seems to arise from special relativity, even if we take the simplest possible system.Again special relativity tries to resolve these questions. What it won't do, however is make the world conform to our everyday expectations of how things should happen. We still need to modify those expectations. But the simple system described earlier shows that these expectations can't be right to start with even without any knowledge of special relativity or any other theory.
Or likewise the simple system can be extended to more complicated ones. If we can show an apparent paradox with a very simple system, it is likely that this same apparent paradox is in operation with more complicated ones such as the biological ones.0 -
If you recall my example of the lightning flashes at either end of the train, there was no mention of relativity itself, no mention of Lorentz transformations etc. The apparent paradox arises purely from the fact that the speed of light is constant for all observers. We simply trace the light as it travels through the system and the paradox arises. Therefore the issue is not that relativity predicts a paradox but rather that the universe works in ways that appear paradoxical to our commonsense notions of how things should be.I would agree, it seems to be paraodoxical; but this is what seems to be implied from relativity.
If you recall the example a few posts back, we didn't have retinas, we just had the light from the flashes arriving at a central point, both on the train and on the platform. A single light detector for each of the observers would suffice here. If there's only one detection event then the flashes arrived simultaneously, if there's two then non-simultaneously.I don't think the observers need to synchronise their clocks with each other, but the clocks located at the retinas or the detectors do need to be synchronised don't they?
We do have measurements that show that the speed of light is constant which, in a way, is perplexing in itself. The paradox arises from this fact.Is this an observation that requires explanation? That is we don't have any experimental observations which correspond to the question in hand, partly because we can't travel at speeds high enough for the effects to be noticeable.
I would prefer to stick with the simple system as described earlier. What I'm trying to argue here is that even if neither of us had heard about relativity but accepted that the speed of light is constant for all observers, then an apparent paradox arises for certain simple systems such a the one described. We have agreed earlier that there is indeed an apparent paradox and done so without recourse to relativity or the Lorentz transformations etc.I know relativity makes other predictions which are partly supported by experimental observations - I don't think there is any evidence for the reciprocity of contractions that relativity predicts - but is it possible to interpret the mathematics of relativity in such a way that it doesn't lead to this apparent paradox?
Though I think you will agree that it is best to start off with the simplest system that demonstrates the phenomenon. If you are trying to figure out how the internal combustion engine works, start of with a simple idealized engine. Avoid unnecessary detail.We can formulate it in such a way that encompasses systems of infinitely varying degrees of complexity, from the most basic to the most complex, without needing to specify the actual set up of the system. When we say that we are dealing with a single physical process, and two different orders of input into that system, which produce the same output, that can refer to the simplest possible system or the most complex. The conclusion remains the same.
The same point about not needing to know about relativity or Lorentz transformations applies here. The apparent paradox arrises even if you don't know the theory.Yes, to each of them the system appears to be operating in a different way but most would agree that this is unsatisfactory and presents a paradox.
It's from special relativity though, that the paradox seems to arise.
Although I don't think clocks as such are necessary in my example earlier, if you look at what you have just said there's an a paradox already. There's nothing to distinguish between observers, they are simply moving relatively to each other. The situation is symmetrical. Therefore we can't say that one clock is moving faster than the other for all observers.What if the clocks of relatively moving observers actually ticked at different rates; what if the clock of one observer moving relative to another actually ticked faster than the others clock, leading to different measurements? Only if we say that one clock is the correct clock would we imply that one of the observers is incorrect, but if we just have clocks which tick at different rates then neither observer is correct or incorrect.
What we can show, however, is that for each each observer, their own clock will appear to them to be moving at the normal rate, however when they observe the other clock it appears to be moving slower.
This, on the face of it, is paradoxical. The clock is a physical system yet appears to operate differently according to the motion of the observer.
Again, this can be shown without knowledge of relativity or Lorentz transformations or anything of that sort. You can show that it is due to the constancy of the speed of light.
I hope you can see that the apparent paradox is there before we bring in the developed theory of relativity. The world really does work in a strange way and we simply can't account for it without developing some new theory and to a certain extent abandoning preexisting notions.The issue seems to arise from special relativity, even if we take the simplest possible system.0 -
and, on the basis of those co-ordinate descriptions, relatively moving observers will disagree over how the physical process operates; they will agree over the output produced by the system, but they will disagree over how the physical system functions to produce that output.
One observer will say that one side of the process starts physically operating before the other, while the other says that the process doesn't start physically operating in sequential order.
Both are supposedly correct, so it implies that the same physical process operates in two different ways, at once.
Is the ordering of events the same for all observers?
And what those co-ordinate labels do is ascribe an order to those events, implying that the order in which physical inputs go into a physical system, and the order in which a physical process starts operating, is different, but equally correct; this implies that the same physical process operates in two different ways, at once.
They will only disagree over the coordinate descriptions of the system, and not the system itself. I.e. The system operates, and we have two different descriptions of that operation, and all descriptions agree with what physically happens by the principle of general covariance.0 -
The processIf you recall my example of the lightning flashes at either end of the train, there was no mention of relativity itself, no mention of Lorentz transformations etc. The apparent paradox arises purely from the fact that the speed of light is constant for all observers. We simply trace the light as it travels through the system and the paradox arises. Therefore the issue is not that relativity predicts a paradox but rather that the universe works in ways that appear paradoxical to our commonsense notions of how things should be.
If you recall the example a few posts back, we didn't have retinas, we just had the light from the flashes arriving at a central point, both on the train and on the platform. A single light detector for each of the observers would suffice here. If there's only one detection event then the flashes arrived simultaneously, if there's two then non-simultaneously.
We do have measurements that show that the speed of light is constant which, in a way, is perplexing in itself. The paradox arises from this fact.
I would prefer to stick with the simple system as described earlier. What I'm trying to argue here is that even if neither of us had heard about relativity but accepted that the speed of light is constant for all observers, then an apparent paradox arises for certain simple systems such a the one described. We have agreed earlier that there is indeed an apparent paradox and done so without recourse to relativity or the Lorentz transformations etc.
Though I think you will agree that it is best to start off with the simplest system that demonstrates the phenomenon. If you are trying to figure out how the internal combustion engine works, start of with a simple idealized engine. Avoid unnecessary detail.
The same point about not needing to know about relativity or Lorentz transformations applies here. The apparent paradox arrises even if you don't know the theory.
I hope you can see that the apparent paradox is there before we bring in the developed theory of relativity. The world really does work in a strange way and we simply can't account for it without developing some new theory and to a certain extent abandoning preexisting notions.
I've taken these together, because I think they can be addressed by the same point. Firstly, I would agree that the simplest possible system should be used, which demonstrates the issue; to borrow form Einstein, it should be made as simple as possible, but not simpler. In this case simply having a single detector at the midpoint between the poles doesn't fully represent the issue, or it makes it less tangible; for that reason we require a simple process where two light detectors are spatially separated and the system processes them; they can arrive at the central processing point in that system; the simple system you suggested earlier in the thread I think should suffice.
I think, however, it is possible to avoid any necessity for providing detail of the system; simply by stating that we are dealing with an undefined physical system with two differing orders of input; here we could be talking about an infinitely simple system or an infinitely complex system. The details aren't entirely necessary here for the question in hand.
Paradox
The paradox seems to arise from the constancy of c, but only when we assume that a constant measurement of c represents an actual constant speed of light. If we think of it in these terms:
If you and I are moving relative to each other and we both measure the speed of light to be 300,000km/s, but, according to you, my clock and measuring stick are contracted, compared to yours; that is, my measuring stick is shorter and my clock runs slower; that means that the measurement of 300,000km/s that I make doesn't represent the same actual speed that your measurement of 300,000km/s; because my km is shorter than yours and my second is longer.
If it is just the measurement of the speed that remains constant, then the paradox doesn't arise.
The situation wouldn't necessarily be symmetrical if it is only the measurement of c which remains constant.Although I don't think clocks as such are necessary in my example earlier, if you look at what you have just said there's an a paradox already. There's nothing to distinguish between observers, they are simply moving relatively to each other. The situation is symmetrical. Therefore we can't say that one clock is moving faster than the other for all observers.
What we can show, however, is that for each each observer, their own clock will appear to them to be moving at the normal rate, however when they observe the other clock it appears to be moving slower.
This, on the face of it, is paradoxical. The clock is a physical system yet appears to operate differently according to the motion of the observer.
Again, this can be shown without knowledge of relativity or Lorentz transformations or anything of that sort. You can show that it is due to the constancy of the speed of light.
If we take the classic thought experiment and look at it from the view of the observer on the platform; we don't tend to have a problem with the idea that that observers clock is ticking slower, form the perspective of that observer.
Now, put yourself in the position of the observer on the train, and for starters imagine that the windows are blacked out, so all you can see is the inside of the train. How would you determine if your clock was running slow or fast? Now, if you were to conduct an experiment to measure the speed of light and you got a value of 300,000km/s, how do you know that the second as measured by you is the same as the second measured by the observer on the platform?0 -
Indeed, we have two descriptions of the physical process. One description says that the inputs go into the system in sequential order and that the system starts physically operating in sequential order, while the other description says that the inputs go in non-sequentially and that the system physically starts operating non-sequentially.They will only disagree over the coordinate descriptions of the system, and not the system itself. I.e. The system operates, and we have two different descriptions of that operation, and all descriptions agree with what physically happens by the principle of general covariance.
Both descriptions of the physical operation of the system are supposedly correct, so it implies that the system physically operates in two different ways.
While both observers agree with what the physical output will be, they disagree over how the system physically operates to generate that output. One says the system physically operates sequentially, the other says non-sequentially.0 -
Indeed, we have two descriptions of the physical process. One description says that the inputs go into the system in sequential order and that the system starts physically operating in sequential order, while the other description says that the inputs go in non-sequentially and that the system physically starts operating non-sequentially.
Both descriptions of the physical operation of the system are supposedly correct, so it implies that the system physically operates in two different ways.
While both observers agree with what the physical output will be, they disagree over how the system physically operates to generate that output. One says the system physically operates sequentially, the other says non-sequentially.
They do not disagree over how the system physically operates. They have different coordinate descriptions of the same physical operation.0 -
There is a lot of strong, compelling theoretical and empirical evidence to suggest that the speed of light is constant, I can show you if you like. The assumption that it is constant wasn't just a guess, Einstein had very good reason to make it, and if he hadn't we probably would have arrived at the same conclusion any way.Paradox
The paradox seems to arise from the constancy of c, but only when we assume that a constant measurement of c represents an actual constant speed of light. If we think of it in these terms:
If you and I are moving relative to each other and we both measure the speed of light to be 300,000km/s, but, according to you, my clock and measuring stick are contracted, compared to yours; that is, my measuring stick is shorter and my clock runs slower; that means that the measurement of 300,000km/s that I make doesn't represent the same actual speed that your measurement of 300,000km/s; because my km is shorter than yours and my second is longer.
If it is just the measurement of the speed that remains constant, then the paradox doesn't arise.
I can show you some of it, but its fa0 -
The reason I've gone for the even simpler system where light itself reaches the central point is that we don't even need to know anything about the Lorentz transformations or special relativity to demonstrate the apparent paradox.The process
I've taken these together, because I think they can be addressed by the same point. Firstly, I would agree that the simplest possible system should be used, which demonstrates the issue; to borrow form Einstein, it should be made as simple as possible, but not simpler. In this case simply having a single detector at the midpoint between the poles doesn't fully represent the issue, or it makes it less tangible; for that reason we require a simple process where two light detectors are spatially separated and the system processes them; they can arrive at the central processing point in that system; the simple system you suggested earlier in the thread I think should suffice.
Can we say that at this point, if we make the assumption that the speed of light is constant, we do indeed get the apparent paradox in this simple system and that we therefore need a way of resolving this paradox? The paradox is that it is a single physical system that appears on the surface to be operating in two different ways yet we know that that can't be the case.
Note: I should just add that when we say that the speed of light is constant we mean that it is constant as measured by the observers' equipment regardless of their motion relative to the source of light or to each other. We don't need to assume that any of them are measuring the "actual speed of light". All we need to assume is that using whatever measuring equipment they have, they all measure the same speed of light.
Having agreed on this we can then see if we can resolve this paradox and then see if this resolution also applies to systems (such as the earlier simple one where we have specially separated light detectors and signals traveling at less than the speed of light). Then finally we can generalize to all physical systems of whatever complexity. Do you agree with this approach?0 -
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.They do not disagree over how the system physically operates. They have different coordinate descriptions of the same physical operation.
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.0 -
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citrus burst wrote: »There is a lot of strong, compelling theoretical and empirical evidence to suggest that the speed of light is constant, I can show you if you like. The assumption that it is constant wasn't just a guess, Einstein had very good reason to make it, and if he hadn't we probably would have arrived at the same conclusion any way.
I can show you some of it, but its fa
On the point about the constancy of light speed; there is a distinction to be made between a consistent measurement of 300,000km/s and the actual speed of light. As mentioned, if I am moving relative to you and I measure the speed of light to be 300,000km/s but my instruments are contracted, then the actual speed of light represented by my 300,000km/s is not the same as the speed represented by your 300,000km/s. We both arrive at the same measurement, but the actual speed as represented by those measurements is different; meaning that light is actually slower for one of us. That would mean that there is no paradox, because the paradox only arises when the actual speed is the same for all observers.The reason I've gone for the even simpler system where light itself reaches the central point is that we don't even need to know anything about the Lorentz transformations or special relativity to demonstrate the apparent paradox.
Can we say that at this point, if we make the assumption that the speed of light is constant, we do indeed get the apparent paradox in this simple system and that we therefore need a way of resolving this paradox? The paradox is that it is a single physical system that appears on the surface to be operating in two different ways yet we know that that can't be the case.
Note: I should just add that when we say that the speed of light is constant we mean that it is constant as measured by the observers' equipment regardless of their motion relative to the source of light or to each other. We don't need to assume that any of them are measuring the "actual speed of light". All we need to assume is that using whatever measuring equipment they have, they all measure the same speed of light.
Having agreed on this we can then see if we can resolve this paradox and then see if this resolution also applies to systems (such as the earlier simple one where we have specially separated light detectors and signals traveling at less than the speed of light). Then finally we can generalize to all physical systems of whatever complexity. Do you agree with this approach?
The contraction of instruments, as opposed to space and time, is, I think, the contention of Lorentzian relativity.0 -
On the point about the constancy of light speed; there is a distinction to be made between a consistent measurement of 300,000km/s and the actual speed of light.
I know right, and that is the hardest point to figure out. Its totally counter intuitive. What is the actual speed of light and what is the measured speed of light?
Yeah I know right, problem is your instruments are never contracted. I mentioned this before, but you glossed over it, maybe you should look back over "proper time, or length." Have to be pedantic here.As mentioned, if I am moving relative to you and I measure the speed of light to be 300,000km/s but my instruments are contracted, then the actual speed of light represented by my 300,000km/s is not the same as the speed represented by your 300,000km/s.
I know right, it seems strange that we should arrive at the same result.We both arrive at the same measurement, but the actual speed as represented by those measurements is different;
Interesting idea. When I go to the bank with €5, will you help me try and convince them that my money is worth more then what it states it is?meaning that light is actually slower for one of us. That would mean that there is no paradox, because the paradox only arises when the actual speed is the same for all observers.
I know right, silly speed of light, pick a speed and stick with it.
I believe you are putting the cart before the horse there. Its space and time that contract, not the instruments.The contraction of instruments, as opposed to space and time, is, I think, the contention of Lorentzian relativity.
As I said before, I'll show you why Einstein believed c was constant. It's actually really interesting, because if you don't take into account Special relativity, you are left with "hidden dynamics."
Any way, at this stage Roosh, I think you've gone a little over your head. We are starting to get into the realm of firstly electrodynamics, and secondly quantum.
I've mentioned before, the compelling evidence for the speed of light to be constant, but its up to you how far you want to push it.0 -
I'm not sure if this is rhetorical, but the example above should demonstrate how we can have the same figure for the measurements, where those figures represent a different speed.citrus burst wrote: »I know right, and that is the hardest point to figure out. Its totally counter intuitive. What is the actual speed of light and what is the measured speed of light?
It might be helpful to think of two people timing the 100m sprint, where one persons clock runs slower than the other; the sprinter will run at one single speed but the measurement of the speed by the observers will be different. The other example is the reverse of that, where both have the same measurement, but the speed represented is different.
I am referring there to Lorentzian relativity, in which it is the instruments, not time and space which are contracted. The paradox seems to arise when the actual speed of light remains constant, but where the issue lies in the measurements, the seeming paradox can be resolved.citrus burst wrote: »Yeah I know right, problem is your instruments are never contracted. I mentioned this before, but you glossed over it, maybe you should look back over "proper time, or length." Have to be pedantic here.
I know right, it seems strange that we should arrive at the same result.
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I know right, silly speed of light, pick a speed and stick with it.
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I believe you are putting the cart before the horse there. Its space and time that contract, not the instruments.
An interesting question is how the time and space in which instruments exist can contract, without affecting the instruments?
But that is a side issue.
No problem, we just pick a currency to convert it to and wait til the currency fluctuates against the euro.citrus burst wrote: »Interesting idea. When I go to the bank with €5, will you help me try and convince them that my money is worth more then what it states it is?
And if you do take it into account you're left assuming that past and future exist, apparently. I'm not sure which is preferable, admitting to a lack of understanding or reasoning in circles?citrus burst wrote: »As I said before, I'll show you why Einstein believed c was constant. It's actually really interesting, because if you don't take into account Special relativity, you are left with "hidden dynamics."
Does the evidence allow us to determine between contracted instruments and contracted space and time?citrus burst wrote: »Any way, at this stage Roosh, I think you've gone a little over your head. We are starting to get into the realm of firstly electrodynamics, and secondly quantum.
I've mentioned before, the compelling evidence for the speed of light to be constant, but its up to you how far you want to push it.0 -
Do you believe this to be the case? Is this your explanation?On the point about the constancy of light speed; there is a distinction to be made between a consistent measurement of 300,000km/s and the actual speed of light. As mentioned, if I am moving relative to you and I measure the speed of light to be 300,000km/s but my instruments are contracted, then the actual speed of light represented by my 300,000km/s is not the same as the speed represented by your 300,000km/s. We both arrive at the same measurement, but the actual speed as represented by those measurements is different; meaning that light is actually slower for one of us. That would mean that there is no paradox, because the paradox only arises when the actual speed is the same for all observers.
The contraction of instruments, as opposed to space and time, is, I think, the contention of Lorentzian relativity.0 -
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 seems you just don't like the idea of ordering between causally unconnected events being frame-dependent. You might not like it, but it is a perfectly consistent framework.0 -
To be honest, I wouldn't be 100% certain, but as far as I know it is a possible alternative.Do you believe this to be the case? Is this your explanation?
The main issue is the one we have been discussing, where the implication appears to be that a single physical system physically operates in two different ways at once.0 -
I don't have too much issue with that, per se, the issue lies in the implications which arise from it, such as has been discussed.It seems you just don't like the idea of ordering between causally unconnected events being frame-dependent. You might not like it, but it is a perfectly consistent framework.
It seems we disagree over what is and what isn't a paradox. To my mind, the implication that both of the following could be true, seems paradoxical:
- a single physical process physically, operates sequentially, where one side starts physically operating before the other
- a single physical process doesn't physically operate sequentially, where both sides start physically operating in unison.
Where the physicality of the ordering is immaterial, because the order in which the physical process physically begins depends on the order in which the non-physically ordered inputs arrive.
It certainly seems that we have a single physical process which physically operates in two different ways at once.0 -
Fair enough although as pointed out already I don't really regard systems in special relativity as operating in two different ways as once but enough has been said on that.To be honest, I wouldn't be 100% certain, but as far as I know it is a possible alternative.
The main issue is the one we have been discussing, where the implication appears to be that a single physical system physically operates in two different ways at once.
This alternative, would it be correct to say that it is compatible with special relativity as regards measurements made by instruments? The Lorentz transformations hold but meaning is different.
For example time is not really dilated but instruments set up record it as dilating in accordance with the Lorentz transformations. Similarly, with length contraction, etc.
Just want to make sure we're talking about the same thing.0 -
Just wondering where you stand on the point you made that it appears paradoxical?Fair enough although as pointed out already I don't really regard systems in special relativity as operating in two different ways as once but enough has been said on that.
To the best of my limited understanding, it is essentially just a different interpretation of the experimental results of special relativity; from what I have encountered it seems that the mathematics are the same, the measurements are the same and the Lorentz transformations hold, but, as you say, the meaning is different. As you say, time is not really dilated and it is the instruments which are contracted not space[time].This alternative, would it be correct to say that it is compatible with special relativity as regards measurements made by instruments? The Lorentz transformations hold but meaning is different.
For example time is not really dilated but instruments set up record it as dilating in accordance with the Lorentz transformations. Similarly, with length contraction, etc.
Just want to make sure we're talking about the same thing.0 -
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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.To the best of my limited understanding, it is essentially just a different interpretation of the experimental results of special relativity; from what I have encountered it seems that the mathematics are the same, the measurements are the same and the Lorentz transformations hold, but, as you say, the meaning is different. As you say, time is not really dilated and it is the instruments which are contracted not space[time].
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.
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.Just wondering where you stand on the point you made that it appears paradoxical?
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.0 -
Plus and MinusThanks. 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.
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?
But the apparent paradox arises from the Einsteinian interpretation, so I don't see how it can be resolved by that interpretation.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.0 -
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.0 -
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.It implies no such thing. The difference between the two descriptions is merely a hyperbolic rotation.
That does seem to suggest that the brain, inside his skull, functions in two different ways at once.0 -
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.0 -
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.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.
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.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?
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.But the apparent paradox arises from the Einsteinian interpretation, so I don't see how it can be resolved by that interpretation.0 -
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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:
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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.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.
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.0 -
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.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.
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.
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.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.
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.
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.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.
Just to understand your position, are you content that there is an apparent paradox?0 -
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.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:
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.0 -
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.0 -
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The issue is that the co-ordinate descriptions seem to imply that the single physical process operates in two different ways, at once.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.
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.0 -
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.0 -
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.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.0 -
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).0 -
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?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).0 -
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.0 -
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.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.0 -
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.0 -
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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?0 -
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