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Absolute motion
Comments
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OK; I think this is probably where the confusion lies. The contention isn't necessarily that there exists a preferred frame of reference, which reflects the true motion of objects. The contention is that we can deduce that at least one of two relatively moving bodies must be in absolute motion.
The existence of an absolute reference frame isn't a necessary assumption, because we are talking about the underlying physical process which the mathemeatical reference frames attempt to describe. We are talking about the nature of motion, as opposed to it's measurement.
The problem probably lies in the historical concept of what "absolute motion" means; it was taken to mean motion relative to an absolute reference frame; but that, of course, would be a contradiction in terms; because what is absolute is not, by definition, relative. So there is no necessity for an absolute reference frame to exist.
"Absolute motion" is a statement about the nature of motion of an object, which is not necessarily a measurable quantity, but it does have deductive consequences. "Absolute motion" is a "yes or no", "either, or" question:
"Is X moving?"
"Is Y moving?"
"Is X or Y moving?"
It is also unqualified statements such as "I am moving" or "I am not moving".
Physical processes
Absolute motion is probably easier to interpret using contextual examples; like the example of the observer walking along the earth. As you mentioned in another thread, the observer cannot determine if it is they that is moving, or if the earth is behaving like a spinning log. Here we have two deductively different scenarios which both account for the relative motion between an observer and the road - actually we have three, where the earth is behaving like a spinning log and the observer is walking at a pace that doesn't exactly offset the rotation of the log.
In all cases, the nature of motion ascribed to each object is different, but all result in the same relative motion. We cannot determine which of the three scenarios is the true one, but we can deduce that one of them has to be, because otherwise there would be no relative motion.
Just to reiterate, absolute motion is not relative i.e. it is not necessarily motion relative to an absolute rest frame, so such an assumption isn't necessary.
I'm not necessarily saying that there exists an absolute velocity, because that would imply some measurable quantity; and measurement, by its very nature, is relative, not absolute.
I'm not so sure that I would say that absolute motion can be deduced from our current understanding of motion, becaues the idea of "our current understanding of motion" is somewhat vague; what is being said is that based on the observation of relative motion - not necessarily contemporary interpretation of that observation - we can deduce, in general, three different scenarios that can account for the relative motion between bodies; each of these scenarios, necessarily, distinguish between the nature of motion of the bodies involved, that is, they make reference to the motion of the body in a manner that isn't necessarily relative i.e. in an absolute manner.
We cannot determine which of the three scenarios is the true one, but we can deduce that one of them has to be, and therefore that at least one of the bodies must absolutely be in motion.
No, I would still maintain that.
Again though, we can outline three general scenarios to account for the relative motion between two bodies, each of which makes reference to the absolute motion of one or the other bodies i.e. by making a statement about the movement of the body, that isn't necessarily relative. So this determines that absolute motion does exist.
There might be some confusion being caused by the conflation of absolute velocity with absolute motion, where the former referes to a measurable quanity, while the latter refers to the nature of motion, which isn't necessarily measurable.
So, absolute velocity doesn't necessarily exist, because it implies some measurable quantity, and measurement is by nature relative, not absolute. Theoretically, if we could determine an absolute reference frame we could possibly perform a measurement which we could label "absolute velocity", even though it would technically be velocity relative to a body at absolute rest; but we cannot determine whether or not a body is at absolute rest or not.
Absolute rest
The issue of absolute rest is somewhat different, and you would be right in saying that it is possible that an absolute rest frame doesn't exist, but this in itself would have two interpretations; firstly, that mathematically constructed reference frames don't have phyiscal existence; and secondly, that an absolute rest frame doesn't exist because there is no object in the universe that is at absolute rest; that is, everything in the universe is absolutely in motion.
This thread is beginning to repeat what has already been said in the other thread. My response to this would be the same as my response here.
Namely, the motion of an object is reference frame dependent. If two objects are in motion with respect to each other, then there is no reference frame that labels both as at rest (Though each has a reference frame where they are at rest, as you acknowledge in your post above). This does not establish any form of "intrinsic" motion independent of reference frames.
To put it another way:roosh wrote:In all cases, the nature of motion ascribed to each object is different, but all result in the same relative motion. We cannot determine which of the three scenarios is the true one, but we can deduce that one of them has to be, because otherwise there would be no relative motion.
Relativity says all three scenarios are true.0 -
Indeed, we are repeating ourselves, and the point raised above has been addressed several times in this thread alone. The measurement of relative motion is frame dependent; the nature of motion isn't.This thread is beginning to repeat what has already been said in the other thread. My response to this would be the same as my response here.
Namely, the motion of an object is reference frame dependent. If two objects are in motion with respect to each other, then there is no reference frame that labels both as at rest (Though each has a reference frame where they are at rest, as you acknowledge in your post above). This does not establish any form of "intrinsic" motion independent of reference frames.
When you talk about motion being frame dependent, you are talking about relative motion, not absolute motion; absolute motion pertains to the nature of motion of an object, and isn't necessarily a measurable quantity, and hence doesn't require a reference frame to define it. As said before, it is a "yes or no", "either, or" question.
The observation of relative motion, as opposed to the measurement of relative velocity, allows us to determine three physically distinct scenarios which all ascribe the nature of motion to the relatively moving objects, in deductively different ways.
In each scenario, the implication is that the "intrinsic" motion of each object is different from the other scenarios.
The three scenarios are physically different, with different deductive consequences; they can't all be simultaneously true.To put it another way:
Relativity says all three scenarios are true.0 -
Indeed, we are repeating ourselves, and the point raised above has been addressed several times in this thread alone. The measurement of relative motion is frame dependent; the nature of motion isn't.
And as I have responded, the nature of motion that is absolute is the relation between objects that persist in all reference frames, and not some notion of intrinsic absolute velocity.When you talk about motion being frame dependent, you are talking about relative motion, not absolute motion; absolute motion pertains to the nature of motion of an object, and isn't necessarily a measurable quantity, and hence doesn't require a reference frame to define it. As said before, it is a "yes or no", "either, or" question.
"Am I moving?" Is frame-dependent. What ever frame-independent questions you can construct, that question will always be frame-dependent.The observation of relative motion, as opposed to the measurement of relative velocity, allows us to determine three physically distinct scenarios which all ascribe the nature of motion to the relatively moving objects, in deductively different ways.
In each scenario, the implication is that the "intrinsic" motion of each object is different from the other scenarios.
The three scenarios are physically different, with different deductive consequences; they can't all be simultaneously true.
These scenarios are physically identical. That is the entire revelation of relativity: The physical indistinguishability of reference frames. Perhaps you mean metaphysically distinct. Again, this is only true if you tacitly assume frame-dependent statements are actually "absolute" statements.0 -
The problem is you are conflating absolute statements, about the relative motion between two objects, with statements about the absolute nature of motion of an object.And as I have responded, the nature of motion that is absolute is the relation between objects that persist in all reference frames, and not some notion of intrinsic absolute velocity.
"I am moving relative to X" is an absolute statement about the relative motion between two objects; while, "I am moving" is an absolute statement about the intrinsic motion of an object.
We can see how the question "Am I moving?" pertains to the intrinsic motion of an object, by considering the example of the two trains at rest, relative to each other in a train station, when the trains start moving relative to each other."Am I moving?" Is frame-dependent. What ever frame-independent questions you can construct, that question will always be frame-dependent.
The question "am I, or is our train, moving; or is it the other train that is moving?" clearly pertains to a question of absolute motion; the reason being, there is absolute no doubt whatsoever about the fact that both trains are moving relative to each other, nor is there any doubt that the observer is at rest relative to their train.
The question is asking, which train is actually moving i.e. the intrinsic motion of which train changes?
I think you might mean that they are mathematically identical, which of course doesn't mean that they are physically identical. I am talking about physical scenarios, which are deductively different from each other. I'm not sure which term best applies, but whatever it is, I'm talking about the physical world, not mathematical reference frames.These scenarios are physically identical. That is the entire revelation of relativity: The physical indistinguishability of reference frames. Perhaps you mean metaphysically distinct. Again, this is only true if you tacitly assume frame-dependent statements are actually "absolute" statements.0 -
Light moves in absolute terms under certain conditions and can be used as reference for everything else. Stuff moves in relative terms but also in absolute terms, it just takes more effort ti figure out the numbers.0
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The problem is you are conflating absolute statements, about the relative motion between two objects, with statements about the absolute nature of motion of an object.
I have been saying that such a conflation is the problem. I.e. You have been showing that it is logically true that one object must be moving relative to the other. You have been arguing for absolute statements about relative motion. But you then confuse absolute statements about relative motion with statements about "absolute motion"."I am moving relative to X" is an absolute statement about the relative motion between two objects; while, "I am moving" is an absolute statement about the intrinsic motion of an object.
And you must show that intrinsic motion is a logical necessity. I am saying it is not a logical necessity. We are perfectly consistent in stating that absolute motion, in the sense of "I am moving" is meaningless, and only "I am moving, relative to X" is needed.We can see how the question "Am I moving?" pertains to the intrinsic motion of an object, by considering the example of the two trains at rest, relative to each other in a train station, when the trains start moving relative to each other.
The question "am I, or is our train, moving; or is it the other train that is moving?" clearly pertains to a question of absolute motion; the reason being, there is absolute no doubt whatsoever about the fact that both trains are moving relative to each other, nor is there any doubt that the observer is at rest relative to their train.
"My train is moving." and "The other train is moving." are both correct answers, provided the appropriate frame is referenced. You are saying one must be less correct, due to intrinsic motion, but you have not established intrinsic motion.I think you might mean that they are mathematically identical, which of course doesn't mean that they are physically identical. I am talking about physical scenarios, which are deductively different from each other. I'm not sure which term best applies, but whatever it is, I'm talking about the physical world, not mathematical reference frames.
They are mathematically different. They are physically identical. If they were not, we could tell them apart by looking at their physics. You yourself have acknowledged this point.0 -
Indeed it is the probelm.I have been saying that such a conflation is the problem. I.e. You have been showing that it is logically true that one object must be moving relative to the other. You have been arguing for absolute statements about relative motion. But you then confuse absolute statements about relative motion with statements about "absolute motion".
You are conflating an absolute statement about the relative motion between objects - "I am moving relative to X" - with a statement about the absolute nature of motion, of an object - "I am moving".
"I am moving" is a statement distinct from "I am moving relative to X"; and it is a statement about the absolute nature of motion, precisely because it doesn't relate the motion to anything else; it is a statement about the intrinsic motion of an object.
3 scenarios
The three scenarios outlined, are three distinct cases, where the intrinsic motion of the objects is ascribed differently; in each scenario, the object that is "doing the moving" is different, and hence, the statement about the absolute nature of motion, in each case is different i.e. "I am moving" doesn't apply to all three scenarios, it only applies to two.
On the other hand, the absolute statement about the relative motion of the objects applies in all three cases.
This is precisely what the three scenarios do; they provide the three distinct scenarios that can account for the relative motion; each one is deductively different, and each one carries different implications about the absolute nature of motion of the objects involved.And you must show that intrinsic motion is a logical necessity. I am saying it is not a logical necessity. We are perfectly consistent in stating that absolute motion, in the sense of "I am moving" is meaningless, and only "I am moving, relative to X" is needed.
While we cannot determine which of the three scenarios are true, it is a logical necessity that one of them must be, otherwise there would be no relative motion to account for.
The logical necessity of one of the scenarios means we can deduce that the nature of motion must be absolute, or that the objects must have some intrinsic motion.
Again, the logical necessity of one of the three scenarios, to account for the observation of relative motion, establishes intrinsic motion; because one of them has to be correct."My train is moving." and "The other train is moving." are both correct answers, provided the appropriate frame is referenced. You are saying one must be less correct, due to intrinsic motion, but you have not established intrinsic motion.
But, "my train is moving" is a statement about the intrinsic motion of the train, because it doesn't make reference to any relatively moving object. The same applies for the statement "the other train is moving". They don't require a reference frame to define the movement, because they are statements about what object is "doing the moving".
You are saying that "my train is moving" and "the other train is moving" are both correct answers, provided the appropriate frame is referenced; what this is effectively saying is that "my train is moving relative to the other train" - appropriate frame is referenced - and "the other train is moving relative to my train" - appropriate frame is referenced; this of course is true, but these are absolute statements about the relative motion of two objects.
You are effectively just repeating what has been said before, that "I am moving" is not a valid statement without saying "relative to X"; but this is conflating absolute statements about relative motion with statements about the absolute nature of motion of an object - of which, "I am moving" is one.
Again, the three scenarios distinguish between the intrinsic motion of the objects, and by logical necessity, one of the three scenarios must be true, because otherwise there would be no relative motion.
I think this is where the confusion lies; the erroneous conclusion that all three must be the same, because we cannot distinguish between them by means of a scientific experiment; I think this more highlights the limitation of experiments in determining absolute properties, than it does anything about the absolute nature of objects.They are mathematically different. They are physically identical. If they were not, we could tell them apart by looking at their physics. You yourself have acknowledged this point.
Of course, while we may not be able to distinguish between them experimentally, we can deduce that they each carry different logical implications; and thus, we can determine that they must be physically different.
Essentially, it is a question of, is there a physical difference between walking on a treadmill and walking down the road?0 -
Indeed it is the probelm.
You are conflating an absolute statement about the relative motion between objects - "I am moving relative to X" - with a statement about the absolute nature of motion, of an object - "I am moving".
"I am moving" is a statement distinct from "I am moving relative to X"; and it is a statement about the absolute nature of motion, precisely because it doesn't relate the motion to anything else; it is a statement about the intrinsic motion of an object.
3 scenarios
The three scenarios outlined, are three distinct cases, where the intrinsic motion of the objects is ascribed differently; in each scenario, the object that is "doing the moving" is different, and hence, the statement about the absolute nature of motion, in each case is different i.e. "I am moving" doesn't apply to all three scenarios, it only applies to two.
On the other hand, the absolute statement about the relative motion of the objects applies in all three cases.
This is precisely what the three scenarios do; they provide the three distinct scenarios that can account for the relative motion; each one is deductively different, and each one carries different implications about the absolute nature of motion of the objects involved.
While we cannot determine which of the three scenarios are true, it is a logical necessity that one of them must be, otherwise there would be no relative motion to account for.
The logical necessity of one of the scenarios means we can deduce that the nature of motion must be absolute, or that the objects must have some intrinsic motion.
Again, the logical necessity of one of the three scenarios, to account for the observation of relative motion, establishes intrinsic motion; because one of them has to be correct.
But, "my train is moving" is a statement about the intrinsic motion of the train, because it doesn't make reference to any relatively moving object. The same applies for the statement "the other train is moving". They don't require a reference frame to define the movement, because they are statements about what object is "doing the moving".
Again, the three scenarios distinguish between the intrinsic motion of the objects, and by logical necessity, one of the three scenarios must be true, because otherwise there would be no relative motion.
You are implicitly assuming intrinsic motion to argue that the three scenarios are different. You are then arguing that intrinsic motion is a logical necessity because the three scenarios are different. This is circular reasoning.
Relativity says the three scenarios are just different ways of labelling the same scenario.You are saying that "my train is moving" and "the other train is moving" are both correct answers, provided the appropriate frame is referenced; what this is effectively saying is that "my train is moving relative to the other train" - appropriate frame is referenced - and "the other train is moving relative to my train" - appropriate frame is referenced; this of course is true, but these are absolute statements about the relative motion of two objects.
You are effectively just repeating what has been said before, that "I am moving" is not a valid statement without saying "relative to X"; but this is conflating absolute statements about relative motion with statements about the absolute nature of motion of an object - of which, "I am moving" is one.
I am not conflating anything. I have been very precise about what I mean. "I am moving, relative to X." is an absolute statement. "I have an absolute velocity/intrinsic motion." is a metaphysical statement, an untestable assumption, and in no way logically necessary.I think this is where the confusion lies; the erroneous conclusion that all three must be the same, because we cannot distinguish between them by means of a scientific experiment; I think this more highlights the limitation of experiments in determining absolute properties, than it does anything about the absolute nature of objects.
Of course, while we may not be able to distinguish between them experimentally, we can deduce that they each carry different logical implications; and thus, we can determine that they must be physically different.
That intrinsic motion exists a priori in nature is an assumption that is in no way supported by relativity. Again, you must show that intrinsic motion is a logical necessity. So far, all you have shown is absolute statements about relative motion can be made.
Essentially, it is a question of, is there a physical difference between walking on a treadmill and walking down the road?[/QUOTE]0 -
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Indeed it is the probelm.
You are conflating an absolute statement about the relative motion between objects - "I am moving relative to X" - with a statement about the absolute nature of motion, of an object - "I am moving".
"I am moving" is a statement distinct from "I am moving relative to X"; and it is a statement about the absolute nature of motion, precisely because it doesn't relate the motion to anything else; it is a statement about the intrinsic motion of an object.
3 scenarios
The three scenarios outlined, are three distinct cases, where the intrinsic motion of the objects is ascribed differently; in each scenario, the object that is "doing the moving" is different, and hence, the statement about the absolute nature of motion, in each case is different i.e. "I am moving" doesn't apply to all three scenarios, it only applies to two.
On the other hand, the absolute statement about the relative motion of the objects applies in all three cases.
This is precisely what the three scenarios do; they provide the three distinct scenarios that can account for the relative motion; each one is deductively different, and each one carries different implications about the absolute nature of motion of the objects involved.
While we cannot determine which of the three scenarios are true, it is a logical necessity that one of them must be, otherwise there would be no relative motion to account for.
The logical necessity of one of the scenarios means we can deduce that the nature of motion must be absolute, or that the objects must have some intrinsic motion.
Again, the logical necessity of one of the three scenarios, to account for the observation of relative motion, establishes intrinsic motion; because one of them has to be correct.
But, "my train is moving" is a statement about the intrinsic motion of the train, because it doesn't make reference to any relatively moving object. The same applies for the statement "the other train is moving". They don't require a reference frame to define the movement, because they are statements about what object is "doing the moving".
Again, the three scenarios distinguish between the intrinsic motion of the objects, and by logical necessity, one of the three scenarios must be true, because otherwise there would be no relative motion.
You are implicitly assuming intrinsic motion to argue that the three scenarios are different. You are then arguing that intrinsic motion is a logical necessity because the three scenarios are different. This is circular reasoning.
Relativity says the three scenarios are just different ways of labelling the same scenario.You are saying that "my train is moving" and "the other train is moving" are both correct answers, provided the appropriate frame is referenced; what this is effectively saying is that "my train is moving relative to the other train" - appropriate frame is referenced - and "the other train is moving relative to my train" - appropriate frame is referenced; this of course is true, but these are absolute statements about the relative motion of two objects.
You are effectively just repeating what has been said before, that "I am moving" is not a valid statement without saying "relative to X"; but this is conflating absolute statements about relative motion with statements about the absolute nature of motion of an object - of which, "I am moving" is one.
I am not conflating anything. I have been very precise about what I mean. "I am moving, relative to X." is an absolute statement. "I have an absolute velocity/intrinsic motion." is a metaphysical statement, an untestable assumption, and in no way logically necessary.I think this is where the confusion lies; the erroneous conclusion that all three must be the same, because we cannot distinguish between them by means of a scientific experiment; I think this more highlights the limitation of experiments in determining absolute properties, than it does anything about the absolute nature of objects.
Of course, while we may not be able to distinguish between them experimentally, we can deduce that they each carry different logical implications; and thus, we can determine that they must be physically different.
That intrinsic motion exists a priori in nature is an assumption that is in no way supported by relativity, nor is it a logical consequence of relativity. Again, you must show that intrinsic motion is a logical necessity. So far, all you have shown is absolute statements about relative motion can be made.0 -
I think that it can be argued that there is no object that can exist and be at absolute rest since all matter is composed of dynamical systems. All matter is in chaotic motion at the quantum level.
Take the train before it starts to move. Even then it is moving. There are no two consecutive moments when the train entirely occupies the same space. It is bending, flexing, expanding and contracting due to temperature differentials. And if the engine is running, there are vibrations that cause the train to deform along its entire length. Every point of the train would be in relative motion to every other point of the train.
It could be said then that there is no reference frame from which any point of the train can be said to be at absolute rest except from the point's own frame of reference in which case that point would be uniquely at rest and the rest of the universe would be in absolute motion.
Of course, when the train begins to move, even that point of the train would be in absolute motion.
At a sub-atomic level, nothing is motionless.
I think the poll is badly worded too as I don't see how the descriptor that goes with the 'no' option denies the posibility of absolute motion.0 -
The three scenarios are different real world scenarios; I might be a bit presumptuous in thinking that you have experienced both walking down the road (or driving) and walking on a treadmill, escalator, or other such device, but would you say that they are the exact same thing, or is there a difference? I think most people would agree that there is a difference.You are implicitly assuming intrinsic motion to argue that the three scenarios are different. You are then arguing that intrinsic motion is a logical necessity because the three scenarios are different. This is circular reasoning.
Relativity says the three scenarios are just different ways of labelling the same scenario.
Of course, assuming intrinsic motion isn't an issue; we are perfectly entitled to do so. The point, however, isn't that intrinsic motion is a necessity because the three scenarios are different; the point is that intrinsic motion is a logical necessity because one of the scenarios has to be true, in order to account for the relative motion.
Relativity's labels
Given just the walking observer and the road, relativity cannot account for the 3 three scenarios; a third object, or observer, has to be introduced to account for the third - where both the road and the observer are in motion - thus the point about relativity saying that the three scenarios are just different ways of labeling the same scenario, is incorrect; because the scenario where there is just the walker and the road, gives rise to the three scenarios.
Light clock
It might help to introduce a light clock into the scenario, to try and distinguish between them.
Forgive me if I'm being too presumptuous in presuming that you have experience of both walking down the road and walking on a treadmill, ecalator, or any other such automated contraption; driving down the road also works, but perhaps more difficult to relate it to the experience of driving on a treadmill.
Scenario
Let's try and set the scene; there is you, the street and the surrounding buildings; we can say that you are in a car on the road, or perhaps are just walking and have a box all around you, for reference. You are on the way to a shop, which is a short distance down the road.
Imagine that the road is a treadmill, which can either be on, or off. When it is switched on, it moves in the opposite direction to the direction you are going to the shop - include whatever relative qualifiers are necessary.
Treadmill; on:
Let's imagine that the treadmill is on and you are walking against it, such that the pace you are walking at exactly offsets the pace of the treadmill; your position relative to the surrounding buildings doesn't change, and the distance between you and the shop remains the same. You are also carrying a light-clock.
While walking at this pace, the photon in your light clock travels between the midpoints of the two mirrors, such that the round trip of the photon is twice the distance between the mirrors 2d), as measured relative to your surrounding box, and the surrounding buildings. An important point is that, while walking against the treadmill at this pace, the photon reflects off each mirror such that the path it traces is perpendicular to each mirror.
Hammertime
Now imagine that you stop walking, such that you get taken along with the treadmill; you start moving relative to the surrounding buildings, and the distance between you and the shop starts to increase.
Now, lets say that you stopped walking against the treadmill at precisely the point at which the photon is leaving the midpoint of one of the mirrors. Will the photon trace a path perpendicular to the mirror?
You are saying that the statement "my train is moving" is the same as "my train is moving relative to X"; thus, you are conflating a statement about the absolute nature of motion with an absolute statement about relative motion.I am not conflating anything. I have been very precise about what I mean. "I am moving, relative to X." is an absolute statement. "I have an absolute velocity/intrinsic motion." is a metaphysical statement, an untestable assumption, and in no way logically necessary.
The question which arises from the familiar "is our train is moving" experience, is not "is our train moving relative to me", or "is our train moving relative to the other train"; indeed, it is the relative motion of the two trains which cause us to ask the question "is my train moving [full stop]." This is a question about the absolute nature of motion, requesting a statement about the absolute nature of motion, not an absolute statement about the relative motion of the two trains - because the answer to that one is obvious.
You also say that "my train is moving" and "the other train is moving" are correct statements, as long as the appropriate frame is referenced; meaning "my train is moving relative to the other train" and "the other train is moving relative to my train" are correct statements; thus again, conflating a statement about the absolute nature of motion - "my train is moving" - with an absolute statement about relative motion - "my train is moving relative to the other train".
"My train is moving" is an statement about the absolute nature of motion of the train, just "the other train is moving" is a statement about the absolute nature of motion of the other train; it is a logical necessity that one or the other must be true, and thus, a logical necessity that absolute motion exists.
That it can't be measured simply means that absolute motion isn't relative; but that it can't be measured doesn't mean that it doesn't have deductive consequences.
I'm not suggesting that it is supported by relativity, nor a logical consequence of relativity - the Einsteinian theory that is; I'm saying that it can be deduced from the observation of relative motion.That intrinsic motion exists a priori in nature is an assumption that is in no way supported by relativity, nor is it a logical consequence of relativity. Again, you must show that intrinsic motion is a logical necessity. So far, all you have shown is absolute statements about relative motion can be made.
It has been demonstrated that we can, and do, make statements about the absolute nature of motion; and also that it is a logical necessity.0 -
I think that it can be argued that there is no object that can exist and be at absolute rest since all matter is composed of dynamical systems. All matter is in chaotic motion at the quantum level.
Take the train before it starts to move. Even then it is moving. There are no two consecutive moments when the train entirely occupies the same space. It is bending, flexing, expanding and contracting due to temperature differentials. And if the engine is running, there are vibrations that cause the train to deform along its entire length. Every point of the train would be in relative motion to every other point of the train.
It could be said then that there is no reference frame from which any point of the train can be said to be at absolute rest except from the point's own frame of reference in which case that point would be uniquely at rest and the rest of the universe would be in absolute motion.
Of course, when the train begins to move, even that point of the train would be in absolute motion.
At a sub-atomic level, nothing is motionless.
I think the poll is badly worded too as I don't see how the descriptor that goes with the 'no' option denies the posibility of absolute motion.
Ya, the poll was fairly rushed; It is the "no" part that denies the possibility of absolute motion, while the descriptor appears to be the common response to any question about the existence of absolute motion. It was intended more to see, in general, what camps people fall into; generally it seems to be Einsteinian relativists that disavow the possibility of absolute motion, while making the claim that "only relative motion makes sense".
I would be inclined to agree with you, that it could be argued that no object can be at absolute rest, and would also agree that this doesn't preclude the existence of absolute motion.
I honestly find it incredulous to believe that when people walk down the street, they don't genuinely believe that they are actually moving - or at least, that the physical manifestation of who they believe they are is actually walking.
Or that the Earth isn't actually orbiting the sun. It seems that people have somehow become blinded to the possibility that the Earth is actually orbiting the sun, and we are actually moving about on the surface of the planet.0 -
The three scenarios are different real world scenarios; I might be a bit presumptuous in thinking that you have experienced both walking down the road (or driving) and walking on a treadmill, escalator, or other such device, but would you say that they are the exact same thing, or is there a difference? I think most people would agree that there is a difference.
Most people don't understand the principle of relativity. Relativity says "I am moving." and "The footpath is moving." are different coordinate representations of the same scenario.Of course, assuming intrinsic motion isn't an issue; we are perfectly entitled to do so. The point, however, isn't that intrinsic motion is a necessity because the three scenarios are different; the point is that intrinsic motion is a logical necessity because one of the scenarios has to be true, in order to account for the relative motion.
You are ignoring what I am saying: You are using intrinsic motion to argue that the three scenarios are actually different, and then arguing that intrinsic motion is a logical necessity because they are actually different. That is circular reasoning. I, by the principle of relativity, reject the notion that they are actually different.Relativity's labels
Given just the walking observer and the road, relativity cannot account for the 3 three scenarios; a third object, or observer, has to be introduced to account for the third - where both the road and the observer are in motion - thus the point about relativity saying that the three scenarios are just different ways of labeling the same scenario, is incorrect; because the scenario where there is just the walker and the road, gives rise to the three scenarios.
Relativity says the three scenarios are three coordinate labels of the same scenario, and that coordinate labels do not exist in nature. They are just conventions.
Light clock
It might help to introduce a light clock into the scenario, to try and distinguish between them.
Forgive me if I'm being too presumptuous in presuming that you have experience of both walking down the road and walking on a treadmill, ecalator, or any other such automated contraption; driving down the road also works, but perhaps more difficult to relate it to the experience of driving on a treadmill.
Scenario
Let's try and set the scene; there is you, the street and the surrounding buildings; we can say that you are in a car on the road, or perhaps are just walking and have a box all around you, for reference. You are on the way to a shop, which is a short distance down the road.
Imagine that the road is a treadmill, which can either be on, or off. When it is switched on, it moves in the opposite direction to the direction you are going to the shop - include whatever relative qualifiers are necessary.
Treadmill; on:
Let's imagine that the treadmill is on and you are walking against it, such that the pace you are walking at exactly offsets the pace of the treadmill; your position relative to the surrounding buildings doesn't change, and the distance between you and the shop remains the same. You are also carrying a light-clock.
While walking at this pace, the photon in your light clock travels between the midpoints of the two mirrors, such that the round trip of the photon is twice the distance between the mirrors 2d), as measured relative to your surrounding box, and the surrounding buildings. An important point is that, while walking against the treadmill at this pace, the photon reflects off each mirror such that the path it traces is perpendicular to each mirror.
Hammertime
Now imagine that you stop walking, such that you get taken along with the treadmill; you start moving relative to the surrounding buildings, and the distance between you and the shop starts to increase.
Now, lets say that you stopped walking against the treadmill at precisely the point at which the photon is leaving the midpoint of one of the mirrors. Will the photon trace a path perpendicular to the mirror?
What you are doing is re-introducing the issue of the equivalence principle. I feel a gravitational force the moment the photon is leaving the mirror. This gravitational force pulls the photon off the perpendicular path.You are saying <snip>
I am saying "I am moving, relative to X." is an absolute statement. "I have an absolute velocity/intrinsic motion." is a metaphysical statement, an untestable assumption, and in no way logically necessary.
Therefore, if someone asks "Is my train moving?", if they mean "Is my train moving, relative to X." Then the answer is an absolute statement. If they mean "Is my train intrinsically moving?", then they are presupposing an untestable, superfluous concept, not supported by relativity.I'm not suggesting that it is supported by relativity, nor a logical consequence of relativity - the Einsteinian theory that is; I'm saying that it can be deduced from the observation of relative motion.
And you have not demonstrated as much. You have demonstrated that absolute statements about relative motion can be deduced from observations of relative motion. You have not demonstrated that intrinsic motion can be deduced.0 -
It might help to think of the motion of the train, or any object for that matter, in terms of a 'vector'.
If the motion of the train is referenced to the earth then all the vector quantities; velocity, position, direction, can be accounted for by the energy expenditure of the train. In this respect, I suppose we are treating the earth as being at absolute rest and the train as having absolute motion. This means we can do the maths without having to consider any other motions that the earth experiences due to say the sun's motion around the galaxy.
What we've done here is effectively applied a transformation to the train scenario that cancels out parameters that, if included in the construction of the vector describing the train's motion, would cause the vector to have a complex shape. For instance, the vector for a train travelling at 60 mph would be sensitive to the direction and time of year that the train travelled. Not very useful when producing time-tabels, etc.
But then, if we consider the earth as at absolute rest, we have to consider the sun as being in absolute motion otherwise the notion of a stationary train is meaningless.
The stars and galaxies would all 'acquire' absolute motion depending on which frame of reference was chosen to be at absolute rest. And the choice of the rest frame renders all the frames at every other scale as being in motion. This is contradictory as although we can have an at rest train by choosing earth to be at absolute rest, the train is necessarily comprised of components that are in increasing motion at smaller and smaller scales. So then we have to decide 'what the train is', 'what is it that is moving?'.
It seems that absolute motion is frame dependent. Taking the train again and its vector, by only taking into account the vector quantities accounted for by the train's energy expenditure, there appears to be an implicit assumption that the earth is at absolute rest.0 -
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[Quote:: “walking down the road (or driving) and walking on a treadmill”
Only speak kinematics. This limits the conclusion.
And what do you show the dynamics? For example, the Ives-Stilwell experiment?
The dynamics shows that true change occurs.
An atom – atomic clock – will start to walk in the street. The atomic frequency changes. (This is true change!)
But if the atom do not walking, the frequency remains constant ... (This is true constant.)
This is not just a twin paradox, more than that. Here you will find a solution. The inertial motion is absolute.0 -
I honestly find it incredulous to believe that when people walk down the street, they don't genuinely believe that they are actually moving - or at least, that the physical manifestation of who they believe they are is actually walking.
We do, we just have a way of defining that we are "doing the motion." We say the street is at rest relative to the thing "doing the motion," or are "doing the motion" relative to the street. That way we can tell who is "doing the motion."
Special Relativity is rather limited in the sense that it only works for things at rest or in constant motion, no acceleration. But what it tells us is that although we are free to define whatever rest frame and who is "doing the motion" we want, the results will still be the same.
I'm a bit tired at the moment and will try and elaborate on this later in the day, if I get the chance.
Also Roosh, how do you define motion?0 -
„how do you define motion?”
1. The mass change :
„Nobody doubts the ’reality’ of kinetic energy, otherwise the very reality of energy would have to be denied.” (Dialog about Objections against the Theory of Relativity, Einstein, 1918) and:
"On the Influence of Gravitation on the Propagation of Light" (Einstein (1911), „2. On the Gravitation of Energy”
„One result yielded by the theory of relativity is that the inertia mass of a body increases with the energy it contains; if the increase of energy amounts to E, the increase in inertial mass is equal to E/c², when c denotes the velocity of light.
Now is there an increase of gravitating mass corresponding to this increase of inertia mass? If not, then a body would fall in the same gravitational field with varying acceleration according to the energy it contained. That highly satisfactory result of the theory of relativity by which the law of the conservation of mass is merged in the law of conservation of energy could not be maintained, because it would compel us to abandon the law of the conservation of mass in its old form for inertia mass, and maintain it for gravitating mass.” = true mass change.
Conclusion: Traditionally, the straight-line motion of bodies has only been possible to be characterized with reference to bodies in other inertial motion. After discovering energy, energy types, and their mass attributes, however, the physical characteristics of the motion of a body have been supplemented by these new parameters. A body reaches a new straight-line motion state through an acceleration process. During the the acceleration its physical state will proportionally change. Based on our present knowledge, a body may only be steady straight-line motion if it has the required kinetic energy (Ekinetic > 0) and its mass attribute (mkinetic > 0).
The idea is very old. I like cite:
”I grant there is a difference between an absolute true motion of a body, and a mere relative change of its situation with respect to another body. For when the immediate cause of the change is in the body, that body is truly in motion; and then the situation of other bodies, with respect to it, will be changed consequently, though the cause of that change be not in them.” (Leibniz’s letter to Clarke)0 -
And what I am saying is that without either "I" or the footpath actually moving, there would be no scenario in which either could be labelled as moving.Most people don't understand the principle of relativity. Relativity says "I am moving." and "The footpath is moving." are different coordinate representations of the same scenario.
I have outlined 3 scenarios which can account for the relative motion between two objects; all of which comply with the test of the PoR, and the notion that an observer cannot determine the absolute nature of their motion. How does relativity account for the relative motion between objects i.e. what causes the relative motion that we observe?
Distinguish the threeYou are ignoring what I am saying: You are using intrinsic motion to argue that the three scenarios are actually different, and then arguing that intrinsic motion is a logical necessity because they are actually different. That is circular reasoning. I, by the principle of relativity, reject the notion that they are actually different.
There are two ways of approaching this; firstly, we can present three, real world scenarios, none of which assume intrinsic motion; the experience of walking down the road; the experience of walking on a treadmill; and the experience of walking on a treadmill/automated walkway, where your walking pace doesn't exactly offset the pace of the treadmill/walkway.
Now, these are three real world scenarios, which most people can identify with; is there any assumption of intrinsic motion there? Would you say that these three scenarios are the exact same scenario?
Assume intrinsic motion
We can also assume the intrinsic motion in all three scenarios; but we don't deduce that intrinsic motion is a logical necessity because the three scenarios are different; we deduce that intrinsic motion is a logical necessity because one of the three scenarios has to be correct [in order to account for the observed relative motion].
And to say that you, by the Principle of Relativity, reject the notion that they are actually different, suggests that you don't understand the PoR; because the PoR only allows us to say that we cannot determine which one is correct; it doesn't allow us to conclude that they are not actually different.
And this, as such, isn't an issue, because of the tacit assumption of absolute rest in Einsteinian co-ordinate labeling systems; coupled with the tacit assumption of absolute motion.Relativity says the three scenarios are three coordinate labels of the same scenario, and that coordinate labels do not exist in nature. They are just conventions.
The point again, however, is that, without the idea of intrinsic motion i.e. without one of the objects actually moving, there would be no scenario that would lead to the co-ordinate label "moving".
The other point again, was that given the scenario of just the observer and the road, relativity cannot account for the three scenarios; in order to account for the three scenarios a third object, or reference frame has to be introduced. So, in a scenario where we are talking about the relative motion between a walker and the road, we can deduce three possible scenarios to account for the relative motion - real world scenarios, which don't necessarily assume intrinsic motion - relativity can only account for two of the scenarios given those conditions, meaning that relativity doesn't say that all three scenarios are just different ways of labeling the same scenario.
OK, so we might be able to make a little progress here; you acknowledge that the photon will not travel a path perpendicular between the mirrors?What you are doing is re-introducing the issue of the equivalence principle. I feel a gravitational force the moment the photon is leaving the mirror. This gravitational force pulls the photon off the perpendicular path.
Firstly, how do you go from experiencing no gravitational force, to experiencing a gravitational force, which pulls the photon off the perpendicular path?
Also, the path length of 2d is represented by the perpendicular line between the midpoints of the mirrors; if the photon travels a line that isn't perpendicular to the mirrors, then it won't reach the midpoint of the second mirror; unless the mirrors actually move in such a way as to offset the angle of the photon.
You have also been saying that "my train is moving" is a correct answer provided the relevant frame is referenced; in other words "my train is moving relative to the other train" is correct.I am saying "I am moving, relative to X." is an absolute statement. "I have an absolute velocity/intrinsic motion." is a metaphysical statement, an untestable assumption, and in no way logically necessary.
Therefore, if someone asks "Is my train moving?", if they mean "Is my train moving, relative to X." Then the answer is an absolute statement. If they mean "Is my train intrinsically moving?", then they are presupposing an untestable, superfluous concept, not supported by relativity.
"My train is moving" is a statement about the absolute nature of motion, while "my train is moving relative to the other trian" is an absolute statement; the equivocation is clear.
Either way, we are agreed that "I am moving relative to X" is an absolute statement, while "I am moving" is a statement about the absolute nature of motion. As I have been saying, statements about the absolute nature of motion do indeed make sense, on some level at least, because we make them on a daily basis i.e. "I am moving", "my car is moving", "the traffic isn't moving"; or we ask questions such as "is my train moving", or "is it the other train that is moving".
While there may be no scientific experiment which can determine the absolute nature of motion, that might perhaps be seen more as a limitation of scientific experiment, than a statement about the intrinsic nature of motion. Indeed, the test of the PoR states that we cannot distinguish absolute rest from absolute, inertial motion; although we can determine accelerated motion. Some people seem to mistakenly think this means that absolute motion does not exist, and even go so far as to suggest that this was Galileo's intention; when it is probably more likely that he was trying to demonstrate that the Earth actually orbits the sun as opposed to the Sun circling the Earth - he probably wanted to highlight why we couldn't tell that the Earth was actually moving.
And of course, absolute motion is entirely compatible with the PoR, and one of the possible deductions from it.
We can deduce it on the basis of the logical necessity of one of the three scenarios, to account for the relative motion between the two objects.And you have not demonstrated as much. You have demonstrated that absolute statements about relative motion can be deduced from observations of relative motion. You have not demonstrated that intrinsic motion can be deduced.0 -
And what I am saying is that without either "I" or the footpath actually moving, there would be no scenario in which either could be labelled as moving.
You say this, but you have not logically demonstrated it. And, unless you reject relativity, you cannot logically demonstrate it, since space itself is relative.I have outlined 3 scenarios which can account for the relative motion between two objects; all of which comply with the test of the PoR, and the notion that an observer cannot determine the absolute nature of their motion. How does relativity account for the relative motion between objects i.e. what causes the relative motion that we observe?
The laws of physics cause the relative motion. The laws of physics are invariant, and do not change from reference frame to reference frame.Distinguish the three
There are two ways of approaching this; firstly, we can present three, real world scenarios, none of which assume intrinsic motion; the experience of walking down the road; the experience of walking on a treadmill; and the experience of walking on a treadmill/automated walkway, where your walking pace doesn't exactly offset the pace of the treadmill/walkway.
Now, these are three real world scenarios, which most people can identify with; is there any assumption of intrinsic motion there? Would you say that these three scenarios are the exact same scenario?
Yes, they are the exact same, provided we are careful with what we mean by treadmill. If we, for example treat the rotating earth as the treadmill then yes, the three scenarios are the same.Assume intrinsic motion
We can also assume the intrinsic motion in all three scenarios; but we don't deduce that intrinsic motion is a logical necessity because the three scenarios are different; we deduce that intrinsic motion is a logical necessity because one of the three scenarios has to be correct [in order to account for the observed relative motion].
And to say that you, by the Principle of Relativity, reject the notion that they are actually different, suggests that you don't understand the PoR; because the PoR only allows us to say that we cannot determine which one is correct; it doesn't allow us to conclude that they are not actually different.
You are begging the question again. I am not obliged to assume they are metaphysically different unless they have been shown to be physically distinguishable.And this, as such, isn't an issue, because of the tacit assumption of absolute rest in Einsteinian co-ordinate labeling systems; coupled with the tacit assumption of absolute motion.
No such assumptions exist.The point again, however, is that, without the idea of intrinsic motion i.e. without one of the objects actually moving, there would be no scenario that would lead to the co-ordinate label "moving".
I don't see why you would think this.The other point again, was that given the scenario of just the observer and the road, relativity cannot account for the three scenarios; in order to account for the three scenarios a third object, or reference frame has to be introduced. So, in a scenario where we are talking about the relative motion between a walker and the road, we can deduce three possible scenarios to account for the relative motion - real world scenarios, which don't necessarily assume intrinsic motion - relativity can only account for two of the scenarios given those conditions, meaning that relativity doesn't say that all three scenarios are just different ways of labeling the same scenario.
You keep introducing these scenarios as different, without establishing that they are different. Surely you must see the problem with this.OK, so we might be able to make a little progress here; you acknowledge that the photon will not travel a path perpendicular between the mirrors?
Yes.Firstly, how do you go from experiencing no gravitational force, to experiencing a gravitational force, which pulls the photon off the perpendicular path?
Also, the path length of 2d is represented by the perpendicular line between the midpoints of the mirrors; if the photon travels a line that isn't perpendicular to the mirrors, then it won't reach the midpoint of the second mirror; unless the mirrors actually move in such a way as to offset the angle of the photon.
Before we go any further, do you feel it is relevant to talk about non-inertial motion to argue your case? It will complicate the issue, and I don't think it will be fruitful unless we first agree that, at the very least, inertial motion does not imply intrinsic, absolute motion.
<snipped rest of post, which was reiterations of the above issues>0 -
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But surely, intrinsic motion can be loosely defined as 'the motion of an object that resists changes in relative motion'?
And if a photon can be regarded as having energy then by the equivalence principle, it must also possess inertial mass.
How can intrinsic motion not be implicit if everything is made from energy?0 -
How can intrinsic motion not be implicit if everything is made from energy?
Everything is not made from energy. Energy is a characteristic of something, like charge or spin. Energy doesn't exist on its own, it's a property of something. A photon is not energy, an electron is not energy.
Sorry if its off topic0 -
What does the energy expenditure of the train cause it to do?It might help to think of the motion of the train, or any object for that matter, in terms of a 'vector'.
If the motion of the train is referenced to the earth then all the vector quantities; velocity, position, direction, can be accounted for by the energy expenditure of the train. In this respect, I suppose we are treating the earth as being at absolute rest and the train as having absolute motion. This means we can do the maths without having to consider any other motions that the earth experiences due to say the sun's motion around the galaxy.
Also, to say that "we can do the maths without having to consider any other motions that the earth experiences due to say the sun's motion around the galaxy", implies that the Earth is actually in motion around the sun, and that the sun is actually in motion around the galaxy.
Although I don't fully understand the point about vectors, I would be inclined to agree with you, with regard to the treatment of frames as being at absolute rest.What we've done here is effectively applied a transformation to the train scenario that cancels out parameters that, if included in the construction of the vector describing the train's motion, would cause the vector to have a complex shape. For instance, the vector for a train travelling at 60 mph would be sensitive to the direction and time of year that the train travelled. Not very useful when producing time-tabels, etc.
But then, if we consider the earth as at absolute rest, we have to consider the sun as being in absolute motion otherwise the notion of a stationary train is meaningless.
The stars and galaxies would all 'acquire' absolute motion depending on which frame of reference was chosen to be at absolute rest. And the choice of the rest frame renders all the frames at every other scale as being in motion. This is contradictory as although we can have an at rest train by choosing earth to be at absolute rest, the train is necessarily comprised of components that are in increasing motion at smaller and smaller scales. So then we have to decide 'what the train is', 'what is it that is moving?'.
It seems that absolute motion is frame dependent. Taking the train again and its vector, by only taking into account the vector quantities accounted for by the train's energy expenditure, there appears to be an implicit assumption that the earth is at absolute rest.
A similar, if not the same, point, about the implicit assumption of absolute rest and absolute motion in Einsteinian reference frames, is made in this thread.0 -
I would be inclined to agree that it is us that is "doing the moving", while the street remains passive; that is, we are absolutely in motion, and it is our absolute motion that causes the relative motion between us and the street.citrus burst wrote: »We do, we just have a way of defining that we are "doing the motion." We say the street is at rest relative to the thing "doing the motion," or are "doing the motion" relative to the street. That way we can tell who is "doing the motion."
A very reasonable possibility that seems to be denied by either the principles of relativity, or just Einsteinian relativists, is that the sun is actually in motion through the the galaxy; the Earth is actually in motion through the solar system; and we are actually in motion on the surface of the earth.
The constant recourse seems to be to the fact that we can label either as moving, which is fine, we can, but that doesn't mean that neither is actually moving.
Deductively though, I don't think the results will be the same, when we consider the scenarios where one object is doing the moving, and another object isn't doing any of the moving; we can compare this to where both objects are doing the moving, but it depends on the amount of moving each object is doing.citrus burst wrote: »Special Relativity is rather limited in the sense that it only works for things at rest or in constant motion, no acceleration. But what it tells us is that although we are free to define whatever rest frame and who is "doing the motion" we want, the results will still be the same.
I'm a bit tired at the moment and will try and elaborate on this later in the day, if I get the chance.
Also Roosh, how do you define motion?0 -
The conclusion that space itself is relative is also not a logical necessity, unless absolute motion is rejected; but the conclusion that space itself is relative appears to stem from the treatment of mathematical reference frames as being physical, coupled with the the intrinsic assumption of absolute rest.You say this, but you have not logically demonstrated it. And, unless you reject relativity, you cannot logically demonstrate it, since space itself is relative.
The laws of physics cause the relative motion. The laws of physics are invariant, and do not change from reference frame to reference frame.
In the absence of an explanation as to how world-lines, which are static in spacetime, can give rise to the observation of relative motion, then the necessity of absolute motion, to account for the observation of relative motion, is entirely more logical.
"The laws of physics cause relative motion" does not sufficiently address the question, unfortunately; because the static world-lines, apparently, manifest as the observations which lead us to the laws of physics; the question remains as to how static, spacetime world-lines, give rise to the observation of relative motion, that supposedly lead us to the conclusion that all objects are just static, spacetime world-lines.
Bearing in mind that you have already stated that this is still an open question.
Do you mean if we treat the rotating Earth as a treadmill, as opposed to a non-rotating Earth? Where the walking on the non-rotating Earth is said to be "in motion". Also, do you mean a rotating Earth where the pace of the walking doesn't exactly offset the pace of the rotation?Yes, they are the exact same, provided we are careful with what we mean by treadmill. If we, for example treat the rotating earth as the treadmill then yes, the three scenarios are the same.
We don't have to show that they are physically distinguishable, only that they are logically so; and while you are not obliged to assume anything, we can assume intrinsic motion for the purpose of distinguishing between them; the logical necessity of intrinsic motion then follows from the logical necessity of one of the scenarios to account for relative motion.You are begging the question again. I am not obliged to assume they are metaphysically different unless they have been shown to be physically distinguishable.
You keep maintaining that the three scenarios are different ways of labeling one scenario, but that isn't necessarily correct, without conflating absolute statements about relative motion, with statements about the absolute nature of motion.
Relativity can't say the three scenarios are just different ways of labeling the same thing, because relativity can only make such statements as "I am moving relative to the road" and "the road is moving relative to me". To say that "the road is moving" depends on the frame of reference, is to conflate a statement about the absolute nature of motion of an object with an statement about relative motion. In every frame of reference "the road is moving relative to me".
If relativity says that we can define a reference frame in which the road is moving, and not necessarily moving relative to me, then there is an implicit assumption about the absolute nature of motion, of the road.
It would be more accurate to say that relativity has one way of labeling all three scenarios, as opposed to the idea that all three scenarios are different ways of labeling the same scenario.
If relativity can define a reference frame which labels the road as "moving", and not just "moving relative to me" then there is an implicit assumption about the absolute nature of motion of the road; precisely because "the road is moving" is a statement about the absolute nature of motion, of the road.No such assumptions exist.
I know you don't, that's partly why we are discussing this.I don't see why you would think this.
The reason why I think it though is because I can't see how there would be anything to label as "moving", or even "moving relative to X" if either X or something else wasn't moving; and to date, I haven't encountered any reasonable explanation to the contrary.
And you keep trying to maintain that they are the same, without establishing that they are. Part of the issue might lie in the fact that it should be self-evident, and the difficulty in logically demonstrating something which is self-evident.You keep introducing these scenarios as different, without establishing that they are different. Surely you must see the problem with this.
For example, is it possible to demonstrate the logical validity of the statement "the physical world exists" without implicitly assuming the existence of the physical world?
Cool.Yes.
I think the absolute nature of motion extends to both inertial, and non-inertial motion; an accelerating object would absolutely be in motion as much as a non-accelerating one, that isn't at absolute rest.Before we go any further, do you feel it is relevant to talk about non-inertial motion to argue your case? It will complicate the issue, and I don't think it will be fruitful unless we first agree that, at the very least, inertial motion does not imply intrinsic, absolute motion.0 -
The conclusion that space itself is relative is also not a logical necessity, unless absolute motion is rejected; but the conclusion that space itself is relative appears to stem from the treatment of mathematical reference frames as being physical, coupled with the the intrinsic assumption of absolute rest.
<snip>
This is beginning to sound incredibly silly. You have demonstrated a complete misunderstanding of coordinate systems in another thread, and now you assert, without argument, that relativity treats coordinate systems as physical, and tacitly assumes absolute rest, when we have already established that relativity does not assume absolute rest, and coordinate systems do not have any a priori physical existence. These are the core concepts of relativity. Heck, the whole reason Einstein investigated hyperbolic geometry was to see if absolute velocity was a necessary consequence of electromagnetism. Relativity was formulated precisely to avoid what you accuse it of.
You have gone from honest curiosity about relativity, to crank arguments against it. We cannot even begin to have an honest discussion about absolute motion until you understand that, at the very least, relativity does not suppose it exists, explicitly or implicitly, as an postulate, or a logical consequence of the postulates.
To disagree with relativity is one thing. But to argue that it is something else is another, entirely ridiculous thing, on par with arguing that Darwinian evolution says life was created in 6 days.0 -
You seem to confuse my challenging of the justification for the treatment of co-ordinate systems, in the other thread, with a misunderstanding of them; the discussion continues in the other thread where rational justification has yet to be presented for the requirement of performing a Lorentz transform, from Evelyn's imaginary reference frame to Albert's. Indeed, this is where the argument of the ascription of physical properties to co-ordinate systems comes from; because the argument is that Evelyn performs her measurements in one imaginary reference frame, while performing her calculations inanother; this most certainly ascribes physical characteristics to what is non-physical - but this is the topic in the other thread, so we don't need to rehash it here; it was just worth mentioning in relation to the point that "space itself is relative".This is beginning to sound incredibly silly. You have demonstrated a complete misunderstanding of coordinate systems in another thread, and now you assert, without argument, that relativity treats coordinate systems as physical, and tacitly assumes absolute rest, when we have already established that relativity does not assume absolute rest, and coordinate systems do not have any a priori physical existence. These are the core concepts of relativity. Heck, the whole reason Einstein investigated hyperbolic geometry was to see if absolute velocity was a necessary consequence of electromagnetism. Relativity was formulated precisely to avoid what you accuse it of.
You have gone from honest curiosity about relativity, to crank arguments against it. We cannot even begin to have an honest discussion about absolute motion until you understand that, at the very least, relativity does not suppose it exists, explicitly or implicitly, as an postulate, or a logical consequence of the postulates.
To disagree with relativity is one thing. But to argue that it is something else is another, entirely ridiculous thing, on par with arguing that Darwinian evolution says life was created in 6 days.
We also haven't established that relativity doesn't assume absolute rest; indeed a point raised above, about the formulation, highlights the assumption of absolute rest i.e. statements that "the road is moving" in one reference frame, but not in another, are statements about the absolute nature of motion, not absolute statements about relative motion; such statements implicitly assume absolute rest and motion.
For the purpose of an honest discussion, it may also be helpful if you recognise that the concept of absolute motion is perfectly in keeping with the Principle of Relativity, and that Einsteinian relativity, itself, isn't a logical necessity. In fact, Einsteinian relativity seems to reject the idea of absolute motion, when such a conclusion isn't a logical necessity; on the other hand, Lorentzian relativity can allow for the fact that nothing is at absolute rest, or that certain objects might be at absolute rest, which would be closer to what can actually be deduced from the experimental test of the PoR.
It is also interesting to see that what constitutes a "crank argument", is a logical challenge of relativity.
But we can leave all that to one side, and continue with the points below, which remain unaddressed.
Do you mean if we treat the rotating Earth as a treadmill, as opposed to a non-rotating Earth? Where the walking on the non-rotating Earth is said to be "in motion". Also, do you mean a rotating Earth where the pace of the walking doesn't exactly offset the pace of the rotation?Yes, they are the exact same, provided we are careful with what we mean by treadmill. If we, for example treat the rotating earth as the treadmill then yes, the three scenarios are the same.
We don't have to show that they are physically distinguishable, only that they are logically so; and while you are not obliged to assume anything, we can assume intrinsic motion for the purpose of distinguishing between them; the logical necessity of intrinsic motion then follows from the logical necessity of one of the scenarios to account for relative motion - unless there is a reasonable argument as to how static spacetime world-lines give can give rise to the observation of relative motion.You are begging the question again. I am not obliged to assume they are metaphysically different unless they have been shown to be physically distinguishable.
You keep maintaining that the three scenarios are different ways of labeling one scenario, but that isn't necessarily correct, without conflating absolute statements about relative motion, with statements about the absolute nature of motion.
Relativity can't say the three scenarios are just different ways of labeling the same thing, because relativity can only make such statements as "I am moving relative to the road" and "the road is moving relative to me". To say that "the road is moving" depends on the frame of reference, is to conflate a statement about the absolute nature of motion of an object with an absolute statement about relative motion. In every frame of reference "the road is moving relative to me".
If relativity says that we can define a reference frame in which the road is moving, and not necessarily moving relative to me, then there is an implicit assumption about the absolute nature of motion, of the road.
It would be more accurate to say that relativity has one way of labeling all three scenarios, as opposed to the idea that all three scenarios are different ways of labeling the same scenario.
If relativity can define a reference frame which labels the road as "moving", and not just "moving relative to me" then there is an implicit assumption about the absolute nature of motion of the road; precisely because "the road is moving" is a statement about the absolute nature of motion, of the road.No such assumptions exist.
I know you don't, that's partly why we are discussing this.I don't see why you would think this.
The reason why I think it though is because I can't see how there would be anything to label as "moving", or even "moving relative to X" if either X or something else wasn't moving; and to date, I haven't encountered any reasonable explanation to the contrary.
And you keep trying to maintain that they are the same, without establishing that they are. Part of the issue might lie in the fact that it should be self-evident, and the difficulty in logically demonstrating something which is self-evident.You keep introducing these scenarios as different, without establishing that they are different. Surely you must see the problem with this.
For example, is it possible to demonstrate the logical validity of the statement "the physical world exists" without implicitly assuming the existence of the physical world?
Cool.Yes.
I think the absolute nature of motion extends to both inertial, and non-inertial motion; an accelerating object would absolutely be in motion as much as a non-accelerating one, that isn't at absolute rest.Before we go any further, do you feel it is relevant to talk about non-inertial motion to argue your case? It will complicate the issue, and I don't think it will be fruitful unless we first agree that, at the very least, inertial motion does not imply intrinsic, absolute motion.0 -
citrus burst wrote: »Everything is not made from energy. Energy is a characteristic of something, like charge or spin. Energy doesn't exist on its own, it's a property of something. A photon is not energy, an electron is not energy.
Sorry if its off topic
I'm sorry, I have to disagree. Energy is all that exists. A photon represents a unit of energy and an electron is a source of photons. I think that matter is simply systems of energy that possess almost identical intrinsic motion such that it appears that they are part of the same thing.
As far as I'm concerned, even the vacuum of space is a manisfestation of some of the energy contained in the universe. And it moves. It changes shape. It expands. Nothing is static. Stasis would be non-existence.
In fact, I would say that photons themselves have a great deal of internal structure on account of the dynamic nature of energy. It always moves. It never occupies the same space from one moment to the next. It can't.
How can energy be still?0 -
You seem to confuse my challenging of the justification for the treatment of co-ordinate systems, in the other thread, with a misunderstanding of them; the discussion continues in the other thread where rational justification has yet to be presented for the requirement of performing a Lorentz transform, from Evelyn's imaginary reference frame to Albert's. Indeed, this is where the argument of the ascription of physical properties to co-ordinate systems comes from; because the argument is that Evelyn performs her measurements in one imaginary reference frame, while performing her calculations inanother; this most certainly ascribes physical characteristics to what is non-physical - but this is the topic in the other thread, so we don't need to rehash it here; it was just worth mentioning in relation to the point that "space itself is relative".
We also haven't established that relativity doesn't assume absolute rest; indeed a point raised above, about the formulation, highlights the assumption of absolute rest i.e. statements that "the road is moving" in one reference frame, but not in another, are statements about the absolute nature of motion, not absolute statements about relative motion; such statements implicitly assume absolute rest and motion.
For the purpose of an honest discussion, it may also be helpful if you recognise that the concept of absolute motion is perfectly in keeping with the Principle of Relativity, and that Einsteinian relativity, itself, isn't a logical necessity. In fact, Einsteinian relativity seems to reject the idea of absolute motion, when such a conclusion isn't a logical necessity; on the other hand, Lorentzian relativity can allow for the fact that nothing is at absolute rest, or that certain objects might be at absolute rest, which would be closer to what can actually be deduced from the experimental test of the PoR.
It is also interesting to see that what constitutes a "crank argument", is a logical challenge of relativity.
But we can leave all that to one side, and continue with the points below, which remain unaddressed.
We cannot leave it aside, because it is your fundamental misunderstanding of relativity that is generating all the "unaddressed" issues (issues I have actually addressed before).
So instead of going around in circles, I am dealing with the core issue: Your misunderstanding of what relativity implies.
1) Relativity does not assume coordinate systems exist a priori in nature. This is easily established by looking at how they are applied. Each reference frame corresponds to a hypothetical observer. If you have an event A, then each reference frame will codify how event A is observed. When we want to look at a physical observable, independent of any hypothetical observer, we look at diffeomorphic-invariant properties. These properties/laws/objects are what are considered to exist.
2) Velocity is a frame-dependent property. It is not invariant. Hence, it is not considered to be an intrinsic, physical property of an object. An example of a property that is physical and invariant would be 4-momentum. Another example would be the mass "m" in the energy momentum relation
E^2 = m^2 + p^2
3) Relativity is consistent with the metaphysical assumption of absolute rest/intrinsic motion, but this does not mean it implies it, as relativity is also consistent with the opposite metaphysical assumption.0 -
I'm sorry, I have to disagree. Energy is all that exists. A photon represents a unit of energy and an electron is a source of photons. I think that matter is simply systems of energy that possess almost identical intrinsic motion such that it appears that they are part of the same thing.
As far as I'm concerned, even the vacuum of space is a manisfestation of some of the energy contained in the universe. And it moves. It changes shape. It expands. Nothing is static. Stasis would be non-existence.
In fact, I would say that photons themselves have a great deal of internal structure on account of the dynamic nature of energy. It always moves. It never occupies the same space from one moment to the next. It can't.
How can energy be still?
citrus burst is correct. Energy, like momentum, is a property of the system, not the system itself. Photons, for example, are not energy, but rather quantised excitations of the electromagnetic field.0 -
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I think there might be some confusion between a logical challenge of the rationale provided for Einsteinian relativity, with a lack of understanding of what the theory says. Now, I'm not claiming to be an expert on the theory, far from it, I'm simply saying that we can deduce certain things from the treatment of reference frames in relativity, and some of the statements that, either the theory itself makes, or proponents of the theory make.We cannot leave it aside, because it is your fundamental misunderstanding of relativity that is generating all the "unaddressed" issues (issues I have actually addressed before).
If I'm being honest, it seems as though you are trying to avoid some of the issues that were raised, or else just buy some time, one of the two. It might be a subconscious thing, but that is how it appears, nonetheless.So instead of going around in circles, I am dealing with the core issue: Your misunderstanding of what relativity implies.
The discussion has reached this point organically, where we have both laid out our rationale and questioned each others; unless everything you have stated up until this point has been erroneous, then all of the issues raised remain. I'm also not sure that trying to restate the same point, in another way, is going to help us to avoid going around in circles; if anything, it will just perpetuate the cycle. I will, however, address the points you raise, and then restate the issues that you haven't addressed from the previous posts, in the hope that you might address them. I see that you did address the point about the inverted commas around the word her, but hopefully I won't have to restate the same points three times before they are addressed.
The point about the ascription of physical characteristics, to non-physical reference frames, was based on your formulation of the point thus far; a formulation which is very representative of the language used by proponents of Einstein's relativity, and which carries certain tacit assumptions. Statements such as "Evelyn constructs a reference frame in which she is in motion", not only begs the question relative to what does it label her as "in motion", but where the assumption is "relative to her mathematical reference frame", therein lies the ascription of physical characteristics to the non-physical reference frames.1) Relativity does not assume coordinate systems exist a priori in nature. This is easily established by looking at how they are applied. Each reference frame corresponds to a hypothetical observer. If you have an event A, then each reference frame will codify how event A is observed. When we want to look at a physical observable, independent of any hypothetical observer, we look at diffeomorphic-invariant properties. These properties/laws/objects are what are considered to exist.
When we say that "each reference frame corresponds to a hypothetical observer", we can be more specific than that, and say that, the physical observers Albert, Evelyn, and Henry, are represented in the mathematical reference frames by points, or lines. The mathematical reference frames are supposed to represent the physical scenario. The "hypothetical observers" are the real, pyhsical observers and the mathematical reference frames assist them in their calculations and predictions.
Both Albert's and Evelyn's calculations lead them to paradixical conclusions; unless, of course, their calculations don't correspond to the physical world they seek to describe.
Again, the issue of the assumption of intrinsic motion arises from statement you have made about the treatment of reference frames in relativity; when you say such things as "in one reference frame, the train is labelled as 'in motion'" there is an implicit assumption of the absolute nature of motion of the train; because, to say that "the train is in motion" is a statement about the absolute nature of motion, of the train, not an absolute statement about the relative motion of the train.2) Velocity is a frame-dependent property. It is not invariant. Hence, it is not considered to be an intrinsic, physical property of an object. An example of a property that is physical and invariant would be 4-momentum. Another example would be the mass "m" in the energy momentum relation
E^2 = m^2 + p^2
If you were, however, to say that "in one [or all] reference frame the train is in motion relative to the other train", that would be an absolute statement about the relative motion of the train. But, this would scupper your claim that relativity says that the three, aforementioned, scenarios, are just three ways of labelling the same event, because the three different ways of labeling the same event would require the statements which imply the absolute nature of motion of the train. When we consider that relativity can only make absolute statements about the relative motion of the train, we realise that relativity doesn't say that the three scenarios are different ways of labeling the same scenario; instead, we realise that relativity has only one way of labeling the three scenarios, hence why it appears are though they are the same scenario, under Einsteinian relativity.
I will attempt to physically, distinguish between the three scenarios below.
Again, this is just a paradoxical statement about relativity, because it suggests that, as a description of the universe - with the metaphysical assumptions you say it is compatible with - relativity describes a universe where intrinsic motion exists, but it simultaneously describes a universe where intrinsic motion doesn't exist.3) Relativity is consistent with the metaphysical assumption of absolute rest/intrinsic motion, but this does not mean it implies it, as relativity is also consistent with the opposite metaphysical assumption.
Intrinsic motion cannot both exist, and not exist; to suggest that it can, is a paradox.Unaddressed Issues
1. Physically distinguished
OK, I will attempt to physically distinguish between the three scenarios, which you assert are just the same scenario labeled differently; as highlighted above, however, relativity doesn't say they are the same scenario labeled three different ways; because, to do so, carries the implicit assumption about the absolute motion of the objects i.e. they make statements about the absolute motion of the object, as opposed to absolute statements about relative motion. As relativity only makes absolute statements about the relative motion of objects, it means that, instead of saying that one scenario can be labeled three different ways, three different scenarios can only be labeled one way.
Threadmill
OK, so our three scenarios involve an observer walking on a treadmill, where the street he is walking down is just a giant treadmill - for the purpsoe of clarification.
The three scenarios were said to account for the relative motion as follows:
1) The road is behaving as a giant treadmill; it is actively "doing the moving"; the observers walking pace exaclty offsets the pace of the treadmill, and this accounts for the relative motion.
2) The road isn't behaving like a giant treadmill, it is passive; it is the observers walking action that propels him forward - as opposed to the treadmills action propelling it forward (in the opposite direction); he is actively "doing the moving", and this accounts for the relative motion.
3) Both 1 and 2 above, except the observers walking pace doesn't exactly offset the pace of the treadmill.
The difference
The above is just a restatement of the same scenarios as before, but we can modify them slightly to try and make the physical distinction more clear.
We can drop the, perhaps, confusing idea of the road being a treadmill in #1 and not being a treadmill in #2, and instead simply look for the three scenarios which explain the relative motion between the observer and the treadmill, or conveyor belt. We can, quite easily, distinguish between them, physcially, simply by stating that in #1 the treadmill is switched on, while in #2 the treadmill is switched off. The difference in the physical mechanism for driving the treadmill/conveyor belt, between the "on" and "off" positions serves as a means of distinguishing the first two scenarios physically; while the movement of the walkers limbs relative to his body, allows us to physically distinguish between the other two and the third.
2. Angled Photon
You mentioned above, that the gravitational force, you suddenly feel, pulls the photon off it's perpendicular path:
Firstly, how do you go from experiencing no gravitational force, to experiencing a gravitational force, which pulls the photon off the perpendicular path?
Also, the path length of 2d is represented by the perpendicular line between the midpoints of the mirrors; if the photon travels a line that isn't perpendicular to the mirrors, then it won't reach the midpoint of the second mirror; how does the photon manage to travel between the midpoints of the two mirrors, if it leaves one of the mirrors at an angle that isn't perpendicular?
3. Static worldlines
How do worldlines, which are static in spacetime, give rise to what we observe as relative motion?
Bearing in mind that, "the laws of physics cause relative motion" does not sufficiently address the question, unfortunately; because the static world-lines, apparently, manifest as the observations which lead us to derive the laws of physics; the question remains as to how static, spacetime world-lines give rise to the observation of relative motion.0 -
I think there might be some confusion between a logical challenge of the rationale provided for Einsteinian relativity, with a lack of understanding of what the theory says. Now, I'm not claiming to be an expert on the theory, far from it, I'm simply saying that we can deduce certain things from the treatment of reference frames in relativity, and some of the statements that, either the theory itself makes, or proponents of the theory make.
If I'm being honest, it seems as though you are trying to avoid some of the issues that were raised, or else just buy some time, one of the two. It might be a subconscious thing, but that is how it appears, nonetheless.
The discussion has reached this point organically, where we have both laid out our rationale and questioned each others; unless everything you have stated up until this point has been erroneous, then all of the issues raised remain. I'm also not sure that trying to restate the same point, in another way, is going to help us to avoid going around in circles; if anything, it will just perpetuate the cycle. I will, however, address the points you raise, and then restate the issues that you haven't addressed from the previous posts, in the hope that you might address them. I see that you did address the point about the inverted commas around the word her, but hopefully I won't have to restate the same points three times before they are addressed.
Your issues can be dismissed out of hand, as they do not follow from relativity. That is the problem. You are saying there are logical consequences A B and C because relativity says X Y and Z. Relativity does not say X Y and Z. It says 1) 2) and 3) from my previous post. Do you agree with these points 1) 2) and 3). Because we cannot go any further until you do.The point about the ascription of physical characteristics, to non-physical reference frames, was based on your formulation of the point thus far; a formulation which is very representative of the language used by proponents of Einstein's relativity, and which carries certain tacit assumptions. Statements such as "Evelyn constructs a reference frame in which she is in motion", not only begs the question relative to what does it label her as "in motion", but where the assumption is "relative to her mathematical reference frame", therein lies the ascription of physical characteristics to the non-physical reference frames.
I have addressed this before. She is in motion relative to the hypothetical observer implied by the reference frame. I.e. No tacit assumptions or ascriptions of physical characteristics. Only interpretations of her hypothetical conjecture.When we say that "each reference frame corresponds to a hypothetical observer", we can be more specific than that, and say that, the physical observers Albert, Evelyn, and Henry, are represented in the mathematical reference frames by points, or lines. The mathematical reference frames are supposed to represent the physical scenario. The "hypothetical observers" are the real, pyhsical observers and the mathematical reference frames assist them in their calculations and predictions.
No. The reference frames describe how a scenario might be observed.Again, the issue of the assumption of intrinsic motion arises from statement you have made about the treatment of reference frames in relativity; when you say such things as "in one reference frame, the train is labelled as 'in motion'" there is an implicit assumption of the absolute nature of motion of the train; because, to say that "the train is in motion" is a statement about the absolute nature of motion, of the train, not an absolute statement about the relative motion of the train.
If you were, however, to say that "in one [or all] reference frame the train is in motion relative to the other train", that would be an absolute statement about the relative motion of the train. But, this would scupper your claim that relativity says that the three, aforementioned, scenarios, are just three ways of labelling the same event, because the three different ways of labeling the same event would require the statements which imply the absolute nature of motion of the train. When we consider that relativity can only make absolute statements about the relative motion of the train, we realise that relativity doesn't say that the three scenarios are different ways of labeling the same scenario; instead, we realise that relativity has only one way of labeling the three scenarios, hence why it appears are though they are the same scenario, under Einsteinian relativity.
Non-sequitur. No such statements are needed. We can say the three coordinate systems correspond to three ways of labelling the same event because a coordinate system is merely the description of an event, using a hypothetical observer as a reference. Hence, the three scenarios are the same scenario, viewed three different ways.
<snipped repetition>0 -
I'm not sure how it looks to anyone else reading this - or even if there is anyone else reading it - but, to me, it genuinely appears as though you are trying to avoid addressing the issues that were raised. Like I said, the conversation reached a point organically, where we were both responding to each others points, there was no issue with this until 3 specific points were raised that you might have difficulty addressing. Unless everything you have said up until this point has been incorrect, then all of the points remain. While relativity might not say X, Y, and Z, you have said X, Y, and Z, and the conclusions A, B, and C, have largely come from them. But, of course, that is just speaking in vagaries; the points are there to be seen for anyone who reads them.Your issues can be dismissed out of hand, as they do not follow from relativity. That is the problem. You are saying there are logical consequences A B and C because relativity says X Y and Z. Relativity does not say X Y and Z. It says 1) 2) and 3) from my previous post. Do you agree with these points 1) 2) and 3). Because we cannot go any further until you do.
You seem to be trying to redefine the discussion now, in a manner that might be more comfortable to you; this is just serving the purpose of returning us to the beginning and perpetuating the cycle that you are claiming to try and break. I will address the points you've raised, but will continue to highlight the points you are trying to avoid. I think this might be more of a sub-conscious reaction to having your beliefs challenged, and encountering some issues that you can't immediately address; but I don't doubt that, if you were to take some time, you would be able to find answers to the issues that are in keeping with your beliefs about relativity.
Also, not all of the points have to follow from relativity, and the ones that do, have been discussed on that basis. You're comment that they can be dismissed out of hand, is just your attempt to avoid addressing them.
Again, the question of how she can be in motion relative to a non-physical, hypothetical observer arises; but I will address this point in the "question on time dilation" thread, to which it pertains.I have addressed this before. She is in motion relative to the hypothetical observer implied by the reference frame. I.e. No tacit assumptions or ascriptions of physical characteristics. Only interpretations of her hypothetical conjecture.
I will address this in the same thread.No. The reference frames describe how a scenario might be observed.
Bear in mind that it is you who have been making the statements; I've just been responding to them; but just because it is all hypothetical, it doesn't mean that there aren't hypothetically implied assumptions. Ultimately the question remains as to how accurately the treatment of the reference frames correspond to the physical world; are the reciprocal contractions just hyptothetical artefacts of a mathematical nature, or do they occur in the physical world?Non-sequitur. No such statements are needed. We can say the three coordinate systems correspond to three ways of labelling the same event because a coordinate system is merely the description of an event, using a hypothetical observer as a reference. Hence, the three scenarios are the same scenario, viewed three different ways.
<snipped repetition>
Again, I will address this point in the "question on time dilation thread".Points raised in this thread
Physically distinguish
In this thread, you have repeatedly stated the need to physically distinguish between the three scenarios; that issue has now been addressed, so you should have no trouble proceeding with the point; particularly as this one doesn't need to follow from Einstein's theory of relativity.
Difference
Just to re-iterate the differences; we can consider the relative motion between an observer and a treadmill; there are three, physically distinguished scenarios which can account for the relative motion:
1) The treadmill is switched off, and is passive; the observers walking motion actively causes him to "do the moving" which gives rise to the relative motion between them.
2) The treadmill is switched on; the threadmill is actively "doing the moving"; the observers walking motion exactly offsets the pace of the treadmill; this gives rise to the relative motion between the observer and the treadmill.
3) The treadmill is switched on and is actively "doing the moving"; the observers walking motion doesn't offset the pace of the treadmill exactly; this gives rise to the relative motion between the observer and the treadmill.
There is a physical difference between when the treadmill is switched on, and when it is switched off; when the treadmill is switched on, the motor is activated and drives the belt of the treadmill; the motor is inactive when the treadmill is switched off.
Angled photon
You have said in this threadWhat you are doing is re-introducing the issue of the equivalence principle. I feel a gravitational force the moment the photon is leaving the mirror. This gravitational force pulls the photon off the perpendicular path.
Can you explain how you go from experiencing no gravitational force, to suddenly experiencing a gravitatioal force; the force which pulls the photon off it's perpendicular path?
Can you also explain how a photon can travel a distance of twice the distance between the mid-points of two mirrors - as represented by the perpendicular line between the two points - when the photon doesn't travel perpendicular to the mirrors?
Can you explain how the photon doesn't continue to travel at non-perpendicular angles to the mirrors, without "falling out of the clock"?
Can you explain how the photon can continue to travel a path between the mid-points of the mirrors - a path represented by the perpendicular line between the mirrors - when the photon doesn't travel perpendicular to the mirrors?
Relative motion
You have also said previouslyIn relativity, bodies exist as a world-line (or world-sheet) of events.We exist as a world line, a locus of events, and hence don't actually travel through time
Can you explain how world lines contrive to result in what we observe as relative motion?0 -
I'm not sure how it looks to anyone else reading this - or even if there is anyone else reading it - but, to me, it genuinely appears as though you are trying to avoid addressing the issues that were raised. Like I said, the conversation reached a point organically, where we were both responding to each others points, there was no issue with this until 3 specific points were raised that you might have difficulty addressing. Unless everything you have said up until this point has been incorrect, then all of the points remain. While relativity might not say X, Y, and Z, you have said X, Y, and Z, and the conclusions A, B, and C, have largely come from them. But, of course, that is just speaking in vagaries; the points are there to be seen for anyone who reads them.
You seem to be trying to redefine the discussion now, in a manner that might be more comfortable to you; this is just serving the purpose of returning us to the beginning and perpetuating the cycle that you are claiming to try and break. I will address the points you've raised, but will continue to highlight the points you are trying to avoid. I think this might be more of a sub-conscious reaction to having your beliefs challenged, and encountering some issues that you can't immediately address; but I don't doubt that, if you were to take some time, you would be able to find answers to the issues that are in keeping with your beliefs about relativity.
Also, not all of the points have to follow from relativity, and the ones that do, have been discussed on that basis. You're comment that they can be dismissed out of hand, is just your attempt to avoid addressing them.
Points raised in this thread
<snip>
I have told you before. The issues are being dismissed out of hand because they are issues that do not follow from any informed understanding of relativity. For example, the "three different scenarios" issue does not follow from relativity, as relativity employs reference frames as mathematical constructs codifying events from the perspective of a hypothetical observer. The angled photon issue is not an issue because relativity says the laws of physics are the same under all one-to-one spacetime transformations. It is also an issue you said is not necessary in your argument. It is therefore irrelevant for the time being. (Although it has been addressed before) The worldline issue is not an issue any more or less than Newtonian mechanics is.0 -
I have told you before. The issues are being dismissed out of hand because they are issues that do not follow from any informed understanding of relativity. For example, the "three different scenarios" issue does not follow from relativity, as relativity employs reference frames as mathematical constructs codifying events from the perspective of a hypothetical observer. The angled photon issue is not an issue because relativity says the laws of physics are the same under all one-to-one spacetime transformations. It is also an issue you said is not necessary in your argument. It is therefore irrelevant for the time being. (Although it has been addressed before) The worldline issue is not an issue any more or less than Newtonian mechanics is.
I suppose it is pretty much impossible to discuss anything, in a reasonable manner, when the reply is "it's wrong because relativity says so"; and if you are intent on avoiding issues you were perfectly happy to discuss up until now, then there is nothing I can do.
But, I suppose I may as well try and address the spurious points raised above, if only for posterity.
Follow from relativity
Firslty, the issues don't have to follow from relativity, because we're discussing absolute motion; ultimately, what relativity says is being challenged.
The three different scenarios issue doesn't have to follow from relativity, because we can identify three physically distinguished scenarios without any reference to relativity whatsoever; relativity is being used as a challenge to the validity of the three physically distinguished scenarios, with the assertion that relativity says they are just three ways of labeling the same scenario. What we can deduce, from our discussion, is that relativity can't say they are the same scenario labelled three different ways, without implicit assumptions about either the absolute motion of one body, or the absolute rest of another, and arguably both; that is, without making statements about the absolute nature of motion.
Instead, what relativity can do, is to make absolute statements about relative motion, but this doesn't mean that relativity labels one scenario three different ways, it actually means that relativity only has one way of labeling three physically distinguished scenarios.
Hypotheticals
That "relativity employs reference frames as mathematical constructs, codifying events, from the perspective of a hypothetical observer" doesn't change this fact, that is just an insignificant detail - assuming that everything you had said, up until that point, wasn't completely wrong.
Angled photon
I'm not sure where I said it wasn't necessary, but it isn't really necessary; the conclusion which follows, follows as a necessity though.
Indeed, the angled photon is an issue, but saying that "because relativity says the laws of physics are the same under all one-to-one spacetime transformations" therefore it isn't an issue, is fallacious reasoning. It's some kind of an appeal to authority. The issue is that relativity is being challenged, so stating that "because relativity says so" is not sufficient reasoning.
If "relativity says the laws of physics are the same under all one-to-one spacetime transformations" then it needs to be able to explain how a photon which travels a line that is not perpendicular to the mirrors, in a light clock, can still travel between the midpoints of the mirrors, given that length contraction won't resolve the issue.
It must also explain how a photon can be observed to travel at an angle [other than perpendicular] to the mirrors, according to one observer, but perpendicular according to another.
Indeed, that might represent a way in which an absolute reference frame could be identified, if the angle of a photon with respect to the mirror in a light clock could be measured, you could determine if the clock was at absolute rest or not.
World tubes
The world lines, or more accurately, world tubes, issue, is indeed an issue, because the necessary contention of Einsteinian relativity, or Minkowskian spacetime is that static objects (or world tubes) can give rise to relative motion.
That static objects, that is, absolute objects, absolutely static in spacetime, can give rise to relative motion seems to be somewhat of a paradox, unless there is some mysterious, metaphysical dynamics which can account for it.
Informed understanding of relativity
Bear in mind, the issues that have arisen follow directly from challenges to statements you have made; the challenges have solely been on the basis of logic, so, if your understanding is informed then a logical challenge of that understanding means that issues do indeed follow from an informed understanding.
Unless the statements you've been making up until this juncture have been completely wrong?0 -
I suppose it is pretty much impossible to discuss anything, in a reasonable manner, when the reply is "it's wrong because relativity says so"; and if you are intent on avoiding issues you were perfectly happy to discuss up until now, then there is nothing I can do.
But, I suppose I may as well try and address the spurious points raised above, if only for posterity.
This makes no sense. You have consistently been claiming "relativity implicitly assumes X", and using it to establish your conclusions. When I show that relativity does not assume X, you accuse me of avoiding the issue.Follow from relativity
Firslty, the issues don't have to follow from relativity, because we're discussing absolute motion; ultimately, what relativity says is being challenged.
So are you now challenging what relativity says, as opposed to interpreting what relativity says?The three different scenarios issue doesn't have to follow from relativity, because we can identify three physically distinguished scenarios without any reference to relativity whatsoever; relativity is being used as a challenge to the validity of the three physically distinguished scenarios, with the assertion that relativity says they are just three ways of labeling the same scenario. What we can deduce, from our discussion, is that relativity can't say they are the same scenario labelled three different ways, without implicit assumptions about either the absolute motion of one body, or the absolute rest of another, and arguably both; that is, without making statements about the absolute nature of motion.
Instead, what relativity can do, is to make absolute statements about relative motion, but this doesn't mean that relativity labels one scenario three different ways, it actually means that relativity only has one way of labeling three physically distinguished scenarios.
1) Relativity says coordinate systems do not exist, a priori, in nature.
2)The difference between the three scenarios is the choice of coordinate systems.
3) Therefore, relativity says the differences do not exist, a priori, and are merely artefacts of the mathematics of coordinate systems.Hypotheticals
That "relativity employs reference frames as mathematical constructs, codifying events, from the perspective of a hypothetical observer" doesn't change this fact, that is just an insignificant detail - assuming that everything you had said, up until that point, wasn't completely wrong.
It is the crux of the entire matter.Angled photon
I'm not sure where I said it wasn't necessary, but it isn't really necessary; the conclusion which follows, follows as a necessity though.
Indeed, the angled photon is an issue, but saying that "because relativity says the laws of physics are the same under all one-to-one spacetime transformations" therefore it isn't an issue, is fallacious reasoning. It's some kind of an appeal to authority. The issue is that relativity is being challenged, so stating that "because relativity says so" is not sufficient reasoning.
If "relativity says the laws of physics are the same under all one-to-one spacetime transformations" then it needs to be able to explain how a photon which travels a line that is not perpendicular to the mirrors, in a light clock, can still travel between the midpoints of the mirrors, given that length contraction won't resolve the issue.
It must also explain how a photon can be observed to travel at an angle [other than perpendicular] to the mirrors, according to one observer, but perpendicular according to another.
Indeed, that might represent a way in which an absolute reference frame could be identified, if the angle of a photon with respect to the mirror in a light clock could be measured, you could determine if the clock was at absolute rest or not.
No observer will say the photon travelled between the midpoints of the mirror. All observers agree on what events are co-incident with each other. This is physical. If a photon does not interact with the midpoints of the two mirror for one observer, it will not for all observers. If it were otherwise, you could violate causality, and produce all sorts of paradoxes.
So it does not establish any way in which an absolute reference frame could be identified. What it does do, is establish geodesic from non-geodesic paths.World tubes
The world lines, or more accurately, world tubes, issue, is indeed an issue, because the necessary contention of Einsteinian relativity, or Minkowskian spacetime is that static objects (or world tubes) can give rise to relative motion.
That static objects, that is, absolute objects, absolutely static in spacetime, can give rise to relative motion seems to be somewhat of a paradox, unless there is some mysterious, metaphysical dynamics which can account for it.
This is not a paradox at all. Relative motion is just how the world lines are represented in a given reference frame.Informed understanding of relativity
Bear in mind, the issues that have arisen follow directly from challenges to statements you have made; the challenges have solely been on the basis of logic, so, if your understanding is informed then a logical challenge of that understanding means that issues do indeed follow from an informed understanding.
Unless the statements you've been making up until this juncture have been completely wrong?
Here is a statement I made: Relativity does not implicitly assume absolute motion.
Do you agree with this statement?0 -
I probably should take some of the blame for the confusion, because of the multiple threads, but I haven't been using the claim "relativity says X" to establish my conclusions - unless you could be more specific.This makes no sense. You have consistently been claiming "relativity implicitly assumes X", and using it to establish your conclusions. When I show that relativity does not assume X, you accuse me of avoiding the issue.
You also haven't demonstrated that "relativity doesn't say X"; although, it is quite difficult to speak in such vague terms; I say you are avoiding the issue precisely for such reasons; you are choosing to speak in vague terms, instead of addressing the points that have been raised in the discussion.
Does it really matter? I'm challenging your representation of relativity and it's correspondence to the physical world, along with the logical justification for the resolution of an obvious paradox.So are you now challenging what relativity says, as opposed to interpreting what relativity says?
Bear in mind that your justification for why it isn't a paradox is precisely what is being challenged.
This is pretty much the exact same point as you have been making i.e. the three scenarios are not physically distinguished, and that relativity says that the three scenarios are just different ways of labeling the same thing.1) Relativity says coordinate systems do not exist, a priori, in nature.
2)The difference between the three scenarios is the choice of coordinate systems.
3) Therefore, relativity says the differences do not exist, a priori, and are merely artefacts of the mathematics of coordinate systems.
We have, however, established a physical distinction between then three scenarios; when we consider the relative motion between an observer and a treadmill the treadmill can be "on" or "off" and the walking pace of the observer can vary.
There is a physical difference in physical mechanism, that drives the treadmill, between the "on" and "off" states; and the pace at which the observer walks varies too, which is another physical difference; these differences do exist a priori in nature.
So the difference between the systems isn't just the choice of co-ordinate systems; indeed, the co-ordinate systems apply to all three, physically different scenarios. This doesn't mean that they are all the same, it simply means that relativity does not, or cannot, distinguish between them.
To a certain extent you are correct, because a large part of the contention is that the idea of reciprocal contractions, which gives rise to the paradox, is simply a mathematical artefact and doesn't correspond to nature.It is the crux of the entire matter.
The information you have provided though hasn't materially changed your line of reasoning, and so it is an insignificant detail in that regard.
Indeed, and the paradox it gives rise to is the notion that a clock can tick both faster and slower itself, not to mind another clock; but again, you haven't really addressed the issue. To say that if one observer doesn't observe it then the other won't simply attempts to sidestep the issue.No observer will say the photon travelled between the midpoints of the mirror. All observers agree on what events are co-incident with each other. This is physical. If a photon does not interact with the midpoints of the two mirror for one observer, it will not for all observers. If it were otherwise, you could violate causality, and produce all sorts of paradoxes.
The path length of the 2d forms the basis for the calculation of the Lorentz contraction; the path length of 2d represents the line traced by the photon traveling perpendicular to the two mirrors - the use of the midpoints is entirely arbitrary, as it could be any two points on the mirrors connected by a perpendicular line, the midpoints just help to simplify things.
The amount of time dilation is dependent on the path traced by the photon. Now, you were perfectly happy with the original formulation that the photon traveled between the midpoints of the mirrors, the path represented by a perpendicular line. Indeed, it is a perfectly adequate example.
You then stated that acceleration, or gravity perhaps, would pull the photon off it's perpendicular path. You stated that this was just a re-introduction of the equivalence principle, but you may not have anticipated the line of reasoning; once it became clear you then decided to try and avoid the issue as above.
The question
The question remains; how can the photon in a clock travel between the midpoints of the mirrors - or any other two points - if the photon travels at an angle from either mirror?
The intention isn't to establish an absolute reference frame.So it does not establish any way in which an absolute reference frame could be identified. What it does do, is establish geodesic from non-geodesic paths.
This appears to be a somewhat watered down version of what you said in the thread on the existence of time, that "we exist as wordllines", which of course is an ontological claim.This is not a paradox at all. Relative motion is just how the world lines are represented in a given reference frame.
Indeed, the consequence of Minkowski spacetime, and the block universe, is that we exist as 4 dimensional world-tubes, with an absolute existence; the question remains, how do static world-tubes give rise to the observation of relative motion.
I'm glad you used the indefinite article to highlight that it is just one of a number of statements that you have made, the others of course having been made in this thread an others.Here is a statement I made: Relativity does not implicitly assume absolute motion.
Do you agree with this statement?
I would agree with the above statement, because that isn't necessarily how I would phrase it; I would say that the hypothetical observers represented by co-ordinate labeling systems, in Einsteinian relativity, are treated as being at absolute rest from their own perspective.0 -
I probably should take some of the blame for the confusion, because of the multiple threads, but I haven't been using the claim "relativity says X" to establish my conclusions - unless you could be more specific.
You also haven't demonstrated that "relativity doesn't say X"; although, it is quite difficult to speak in such vague terms; I say you are avoiding the issue precisely for such reasons; you are choosing to speak in vague terms, instead of addressing the points that have been raised in the discussion.
Here is what I am specifically saying: Relativity states that physics exhibits a diffeomorphic invariance. Thus, it cannot have absolute rest, or intrinsic motion as a tacit assumption or logical consequence.
You are saying absolute rest is tacitly assumed. Therefore, because of the above, you are incorrect. Therefore, you have not demonstrated any physical difference between the three scenarios discussed. Therefore, your assertion that there is a metaphysical difference is an assumption, and does not follow from either relativity, or any metaphysical understanding of physics.This is pretty much the exact same point as you have been making i.e. the three scenarios are not physically distinguished, and that relativity says that the three scenarios are just different ways of labeling the same thing.
We have, however, established a physical distinction between then three scenarios; when we consider the relative motion between an observer and a treadmill the treadmill can be "on" or "off" and the walking pace of the observer can vary.
We have not established any such thing. All differences can be accounted for via a coordinate transformation, and unless you assume coordinate systems exist in nature, this means the differences are mathematical artefacts.There is a physical difference in physical mechanism, that drives the treadmill, between the "on" and "off" states; and the pace at which the observer walks varies too, which is another physical difference; these differences do exist a priori in nature.
You are confusing yourself here. We are not talking about a literal treadmill. There are, of course, dynamical differences between an on and off treadmill, such as an electric current, friction, Etc. We are instead talking about the difference between a coordinate system that labels a person as moving and the ground as stationary, and a coordinate system that labels the ground as moving and the person is stationary as if the ground were a giant treadmill.So the difference between the systems isn't just the choice of co-ordinate systems; indeed, the co-ordinate systems apply to all three, physically different scenarios. This doesn't mean that they are all the same, it simply means that relativity does not, or cannot, distinguish between them.
So you have not established any physical difference between the systems.To a certain extent you are correct, because a large part of the contention is that the idea of reciprocal contractions, which gives rise to the paradox, is simply a mathematical artefact and doesn't correspond to nature.
The information you have provided though hasn't materially changed your line of reasoning, and so it is an insignificant detail in that regard.
There are no intrinsic reciprocal contractions. There is a pseudo-Riemannian, hyperbolic geometry, under which observers to measure reciprocal contractions. Just as the dissipation of vibrational energy through air causes observers to measure reciprocal loudness of their radios.Indeed, and the paradox it gives rise to is the notion that a clock can tick both faster and slower itself, not to mind another clock; but again, you haven't really addressed the issue. To say that if one observer doesn't observe it then the other won't simply attempts to sidestep the issue.
The path length of the 2d forms the basis for the calculation of the Lorentz contraction; the path length of 2d represents the line traced by the photon traveling perpendicular to the two mirrors - the use of the midpoints is entirely arbitrary, as it could be any two points on the mirrors connected by a perpendicular line, the midpoints just help to simplify things.
The amount of time dilation is dependent on the path traced by the photon. Now, you were perfectly happy with the original formulation that the photon traveled between the midpoints of the mirrors, the path represented by a perpendicular line. Indeed, it is a perfectly adequate example.
You then stated that acceleration, or gravity perhaps, would pull the photon off it's perpendicular path. You stated that this was just a re-introduction of the equivalence principle, but you may not have anticipated the line of reasoning; once it became clear you then decided to try and avoid the issue as above.
The question
The question remains; how can the photon in a clock travel between the midpoints of the mirrors - or any other two points - if the photon travels at an angle from either mirror?
Indeed? Did you read my response? Again (and again and again), you do not understand what you are arguing against.
In this scenario, all observers agree that the photon does not travel between the midpoints of the mirror. One observer sees the mirrors mover, another observer sees the photon move. Hence, there is no paradox at all.The intention isn't to establish an absolute reference frame.
Now you are just being coy. Your intention to establish a state of intrinsic rest, with which we can construct a mathematical reference frame around, describing absolute motion of objects.This appears to be a somewhat watered down version of what you said in the thread on the existence of time, that "we exist as wordllines", which of course is an ontological claim.
It was not a watered down statement.Indeed, the consequence of Minkowski spacetime, and the block universe, is that we exist as 4 dimensional world-tubes, with an absolute existence; the question remains, how do static world-tubes give rise to the observation of relative motion.
The observation of relative motion is just the representation of world lines in a given reference frame.I'm glad you used the indefinite article to highlight that it is just one of a number of statements that you have made, the others of course having been made in this thread an others.
I would agree with the above statement, because that isn't necessarily how I would phrase it; I would say that the hypothetical observers represented by co-ordinate labeling systems, in Einsteinian relativity, are treated as being at absolute rest from their own perspective.
No. They are treated as at rest with respect to the hypothetical observer implied by the reference frame. Not absolute rest.0 -
Unaddressed Issues
1. Physically distinguished
OK, I will attempt to physically distinguish between the three scenarios, which you assert are just the same scenario labeled differently; as highlighted above, however, relativity doesn't say they are the same scenario labeled three different ways; because, to do so, carries the implicit assumption about the absolute motion of the objects i.e. they make statements about the absolute motion of the object, as opposed to absolute statements about relative motion. As relativity only makes absolute statements about the relative motion of objects, it means that, instead of saying that one scenario can be labeled three different ways, three different scenarios can only be labeled one way.
Threadmill
OK, so our three scenarios involve an observer walking on a treadmill, where the street he is walking down is just a giant treadmill - for the purpsoe of clarification.
The three scenarios were said to account for the relative motion as follows:
1) The road is behaving as a giant treadmill; it is actively "doing the moving"; the observers walking pace exaclty offsets the pace of the treadmill, and this accounts for the relative motion.
2) The road isn't behaving like a giant treadmill, it is passive; it is the observers walking action that propels him forward - as opposed to the treadmills action propelling it forward (in the opposite direction); he is actively "doing the moving", and this accounts for the relative motion.
3) Both 1 and 2 above, except the observers walking pace doesn't exactly offset the pace of the treadmill.
The difference
The above is just a restatement of the same scenarios as before, but we can modify them slightly to try and make the physical distinction more clear.
We can drop the, perhaps, confusing idea of the road being a treadmill in #1 and not being a treadmill in #2, and instead simply look for the three scenarios which explain the relative motion between the observer and the treadmill, or conveyor belt. We can, quite easily, distinguish between them, physcially, simply by stating that in #1 the treadmill is switched on, while in #2 the treadmill is switched off. The difference in the physical mechanism for driving the treadmill/conveyor belt, between the "on" and "off" positions serves as a means of distinguishing the first two scenarios physically; while the movement of the walkers limbs relative to his body, allows us to physically distinguish between the other two and the third.
I will now attempt experimentally to show that the three scenarios above are physically indistinguishable and are simply three ways of describing the same event.
Pretty simple experiment that you can very easily do at home. What you need is a measuring tape (or a yoyo or basically two things attached by a string) and a partner (not important but will highlight things easier).
So the first procedure is easy; get your partner to turn their back, while you pull one end of the tape or the other, or both. Ask them which end moved. Were they right?
The second is the opposite; with your partner's back turned release one end of the tape, or the other, or both. Ask them which end moved. Were they right?
Do those procedures as many times as you want, swap around etc. How many times were you right? How many times were you wrong? What can you conclude?
Seems like a stupid pedantic experiment, but I believe it highlights all there is to (constant) motion. The reason I think a measuring tape is the best is because of the difference in weight between the base of the tape and the metal hook at the end. I feel it is a good approximation between the earth (the base) and something moving on it (the hook). Also the scaled tape itself helps to clarify that at least one end has moved.
Anyway, logically both you and your partner should guess that the base (earth) stays in the same place, while the hook end (you, me, a car etc) moves (this is situation 2 one you described above). If you are smart you could earn a few bob off your partner by keeping the hook in the same place while moving the base (this is situation 1 you described above) or moving both the hook and the base away/towards each other (situation 3).
However, if you do the experiment you will realise you were wrong 66% of the time. So what results can you draw from the experiment? Well from procedure 1; the base moved away from the hook (1), or the hook moved away from the base (2), or they both moved away from each other (3). And similarly from procedure 2; the hook moved towards the base (2), or the base moved towards the hook (1), or they both moved towards each other (3).
What did you observe? Motion between the base and the hook.
What can you conclude? The base and the hook moved away/towards each other. It didn't matter which one moved, from the outside the outcome was the same. Situations 1,2 and 3 are the same.
I realise this a long post so I didn't go into too much detail, so some things may be a bit vague0 -
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cheers citrus, it is a helpful thought experiment, but I think it succeeds more in demonstrating the point I've been making; namely, that three physically distinguished scenarios will all give rise to the same result, but we can deduce that one of the three scenarios has to be correct, without needing to know which specific scenario is actually correct.citrus burst wrote: »I will now attempt experimentally to show that the three scenarios above are physically indistinguishable and are simply three ways of describing the same event.
Pretty simple experiment that you can very easily do at home. What you need is a measuring tape (or a yoyo or basically two things attached by a string) and a partner (not important but will highlight things easier).
So the first procedure is easy; get your partner to turn their back, while you pull one end of the tape or the other, or both. Ask them which end moved. Were they right?
The second is the opposite; with your partner's back turned release one end of the tape, or the other, or both. Ask them which end moved. Were they right?
Do those procedures as many times as you want, swap around etc. How many times were you right? How many times were you wrong? What can you conclude?
Seems like a stupid pedantic experiment, but I believe it highlights all there is to (constant) motion. The reason I think a measuring tape is the best is because of the difference in weight between the base of the tape and the metal hook at the end. I feel it is a good approximation between the earth (the base) and something moving on it (the hook). Also the scaled tape itself helps to clarify that at least one end has moved.
Anyway, logically both you and your partner should guess that the base (earth) stays in the same place, while the hook end (you, me, a car etc) moves (this is situation 2 one you described above). If you are smart you could earn a few bob off your partner by keeping the hook in the same place while moving the base (this is situation 1 you described above) or moving both the hook and the base away/towards each other (situation 3).
However, if you do the experiment you will realise you were wrong 66% of the time. So what results can you draw from the experiment? Well from procedure 1; the base moved away from the hook (1), or the hook moved away from the base (2), or they both moved away from each other (3). And similarly from procedure 2; the hook moved towards the base (2), or the base moved towards the hook (1), or they both moved towards each other (3).
What did you observe? Motion between the base and the hook.
What can you conclude? The base and the hook moved away/towards each other. It didn't matter which one moved, from the outside the outcome was the same. Situations 1,2 and 3 are the same.
I realise this a long post so I didn't go into too much detail, so some things may be a bit vague
The conclusion that "the base and the hook moved away/towards each other", instead of being three ways of describing the same event is just one way of describing three events.
You are right that "it didn't matter which one moved, from the outside the outcome was the same", but instead of that demonstrating that the three situations are the same, you've demonstrated that three, physically distinguished events, give rise to the same result; that is, situations 1,2 and 3 are not actually the same - as you've distinguished between them above - they do however give rise to the same result, so we cannot distinguish which one occurred, but we can deduce, as you mention above, that one of them had to have occurred.0 -
The issue isn't that there is a single absolute rest frame implied, its that every mathematical reference frame implies it; when this is the case the conclusion is inevitable.Here is what I am specifically saying: Relativity states that physics exhibits a diffeomorphic invariance. Thus, it cannot have absolute rest, or intrinsic motion as a tacit assumption or logical consequence.
You are saying absolute rest is tacitly assumed. Therefore, because of the above, you are incorrect. Therefore, you have not demonstrated any physical difference between the three scenarios discussed. Therefore, your assertion that there is a metaphysical difference is an assumption, and does not follow from either relativity, or any metaphysical understanding of physics.
I might not have been explicit enough when I stated above that we can change the thought experiment, remove the road behaving as if it were a giant treadmill and just use a giant treadmill instead.We have not established any such thing. All differences can be accounted for via a coordinate transformation, and unless you assume coordinate systems exist in nature, this means the differences are mathematical artefacts.
You are confusing yourself here. We are not talking about a literal treadmill. There are, of course, dynamical differences between an on and off treadmill, such as an electric current, friction, Etc. We are instead talking about the difference between a coordinate system that labels a person as moving and the ground as stationary, and a coordinate system that labels the ground as moving and the person is stationary as if the ground were a giant treadmill.
So you have not established any physical difference between the systems.
Here we can phsysically distinguish between the three scenarios, as you have outlined above. We could of course physically distinguish between the original three scenarios using other physical phenomena, such as wind resistance, the movement of the walker, or the amount of fuel used in a car; the treadmill is much simpler though, because we can talk about it being "on" or "off".
This begs the question, what do the measurement correspond to; are they just an optical illusion; like when something appears smaller because it is far away; for examplem, like when people take pictures at the salt flats that look as if they are holding the sun, or standing on a wine bottle.There are no intrinsic reciprocal contractions. There is a pseudo-Riemannian, hyperbolic geometry, under which observers to measure reciprocal contractions. Just as the dissipation of vibrational energy through air causes observers to measure reciprocal loudness of their radios.
Or do the measurements correspond to physical objects in a way that isn't just an optical illusion i.e. is a clock measured to actually tick faster and slower than itself?
I did indeed read it.Indeed? Did you read my response? Again (and again and again), you do not understand what you are arguing against.
In this scenario, all observers agree that the photon does not travel between the midpoints of the mirror. One observer sees the mirrors mover, another observer sees the photon move. Hence, there is no paradox at all.
As per the scenario we started with; the photon starts off traveling the perpendicular line between the midpoints of the mirror; the round-trip distance is 2d.
Acceleration or gravity pulls the photon off it's perpendicular trajectory; it has the exact same effect on the observer and the mirrors i.e. they are imparted with the same horizontal velocity as the photon, such that the photon will continue to travel between the midpoints of the mirrors, it just won't trace a perpendicular line.
The question is, how can the photon continue to travel between the midpoints of the mirrors if it changes from it's perpendicular trajectory?
I don't think I could have been much more explicit to be honestNow you are just being coy. Your intention to establish a state of intrinsic rest, with which we can construct a mathematical reference frame around, describing absolute motion of objects.You are of course correct that the assumption of an absolute rest frame is a superfluous assumption, as it isn't required for the notion of absolute motion; absolute motion is motion that is not necessarily defined relative to something; attempting to define absolute motion as being relative to an absolute reference frame is to define absolute motion as being relative, which would be a contradiction in terms.
It's certainly not as strong as saying "we exist as world lines in spacetime"It was not a watered down statement.
This doesn't address the question, and it appears to be a case of the cart before the horse. Relative motion is represented as world lines in a given reference frame; but, if "we exist as world lines" and objects exist as world tubes in spacetime, how do those static worldtubes give rise to what we observe as relative motion.The observation of relative motion is just the representation of world lines in a given reference frame.
It seems as though some kind kind o really mysterious dynamics need to be assumed, for bars of steel as well as bars of smoke.
And the hypothetical observer, or Albert, Henry, and Evelyn, to you and I, is treated as being at absolute rest.No. They are treated as at rest with respect to the hypothetical observer implied by the reference frame. Not absolute rest.0 -
EDIT: We might actually make some progress here. I have removed the parts of my response that I feel would distract us from the important issues, identified below. Namely 1) The implications of a reference frame. 2) How "real" measurements are. and 3) The consistency across different reference frames.
1)The issue isn't that there is a single absolute rest frame implied, its that every mathematical reference frame implies it; when this is the case the conclusion is inevitable.
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And the hypothetical observer, or Albert, Henry, and Evelyn, to you and I, is treated as being at absolute rest.
No statement at all is made about the intrinsic motion of the hypothetical observer. When I arbitrarily choose a reference frame to perform calculations, I am not saying anything about the intrinsic motion of the hypothetical observer implied by the reference frame. I instead construct statements about the motion of things relative to this hypothetical observer. Hence, no mathematical reference frame implies absolute rest. The proof of this is you can make the metaphysical assumption that the hypothetical observer implied by my reference frame has an intrinsic velocity of 2 kph, or 100000 kph, or 0.9999c kph, and my statements will be consistent with any such assumption. Hence, absolute rest is not implied or tacitly assumed.I might not have been explicit enough when I stated above that we can change the thought experiment, remove the road behaving as if it were a giant treadmill and just use a giant treadmill instead.
Here we can phsysically distinguish between the three scenarios, as you have outlined above. We could of course physically distinguish between the original three scenarios using other physical phenomena, such as wind resistance, the movement of the walker, or the amount of fuel used in a car; the treadmill is much simpler though, because we can talk about it being "on" or "off".
In that case, the scenarios just change in a trivial way. Now we have a scenario where the road/treadmill is stationary and the person + surrounding environment is moving, and a scenario where the person + environment is stationary and the road/treadmill is moving.
2)This begs the question, what do the measurement correspond to; are they just an optical illusion; like when something appears smaller because it is far away; for examplem, like when people take pictures at the salt flats that look as if they are holding the sun, or standing on a wine bottle.
Or do the measurements correspond to physical objects in a way that isn't just an optical illusion i.e. is a clock measured to actually tick faster and slower than itself?
Bingo. Space by itself, and time by itself, are "illusions" (though not optical illusions). Any property that depends on a reference frame (i.e. coordinate space and coordinate time, and hence a coordinate present) is not physical. What is physical is the set of events and the geometrical/chronometrical causal structure between them, characterised by a manifold and a metric (To be more technical, we need equivalence classes, but that's not important for the topic of this conversation). This is what is meant by Minkoswki's famous quote.
"Space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind union of the two will preserve an independent reality"
3)I did indeed read it.
As per the scenario we started with; the photon starts off traveling the perpendicular line between the midpoints of the mirror; the round-trip distance is 2d.
Acceleration or gravity pulls the photon off it's perpendicular trajectory; it has the exact same effect on the observer and the mirrors i.e. they are imparted with the same horizontal velocity as the photon, such that the photon will continue to travel between the midpoints of the mirrors, it just won't trace a perpendicular line.
The question is, how can the photon continue to travel between the midpoints of the mirrors if it changes from it's perpendicular trajectory?
I am a little pressed for time, but what I will do in my next reply is plot graphs of what is happening in each reference frame. All I will say now is that, if both the apparatus and the horizontal motion of the photon are 0, relative to the observer, then no non-perpendicular trajectory will be observed.0 -
Cool; I'll continue to highlight any issues that are missed.EDIT: We might actually make some progress here. I have removed the parts of my response that I feel would distract us from the important issues, identified below. Namely 1) The implications of a reference frame. 2) How "real" measurements are. and 3) The consistency across different reference frames.
There is no express statement about intrinsic motion, as it is a tacit assumption. When we say that we can define a reference frame where the hypothetical observer has a velocity of 2kph, etc. we just shift the implicit assumption of absolute rest to the object with the zero velocity.1)
No statement at all is made about the intrinsic motion of the hypothetical observer. When I arbitrarily choose a reference frame to perform calculations, I am not saying anything about the intrinsic motion of the hypothetical observer implied by the reference frame. I instead construct statements about the motion of things relative to this hypothetical observer. Hence, no mathematical reference frame implies absolute rest. The proof of this is you can make the metaphysical assumption that the hypothetical observer implied by my reference frame has an intrinsic velocity of 2 kph, or 100000 kph, or 0.9999c kph, and my statements will be consistent with any such assumption. Hence, absolute rest is not implied or tacitly assumed.
The implicit assumption of absolute rest can be deduced from the depicted behaviour of the photon in a light clock.
Also, when Evelyn " arbitrarily choose a reference frame to perform calculations" she calculates that her and Albert's clock is ticking slower than Henry's.
Again, there is the implicit assumption of absolute movement in those statements, and they are physically distinguished by the treadmill being either on or off.In that case, the scenarios just change in a trivial way. Now we have a scenario where the road/treadmill is stationary and the person + surrounding environment is moving, and a scenario where the person + environment is stationary and the road/treadmill is moving.
What is physical is the clock; the clcok is measured to tick both faster and slower than another physical clock, and by extension, both faster and slower than itself.2)
Bingo. Space by itself, and time by itself, are "illusions" (though not optical illusions). Any property that depends on a reference frame (i.e. coordinate space and coordinate time, and hence a coordinate present) is not physical. What is physical is the set of events and the geometrical/chronometrical causal structure between them, characterised by a manifold and a metric (To be more technical, we need equivalence classes, but that's not important for the topic of this conversation). This is what is meant by Minkoswki's famous quote.
"Space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind union of the two will preserve an independent reality"
This is a physical impossibility, because a clock cannot physically tick faster and slower than itself; so the measurements have to be illusory as opposed to physical. Saying that time and space by themselves are illusions doesn't address the issue.
Another way of stating the paradox is that time is both dilated and undilated for an observer, or that time is measured to be both dilated and undilated by the same, physical clock.
No horizontal trajectory will be observed by observer co-local with the clock, but a relatively moving observer will observer a horizontal trajectory; the reason the co-moving observer won't observe the horizontal trajectory is because his horizontal motion is the same as the mirrors and the photon, so they cancel each other out.3)
I am a little pressed for time, but what I will do in my next reply is plot graphs of what is happening in each reference frame. All I will say now is that, if both the apparatus and the horizontal motion of the photon are 0, relative to the observer, then no non-perpendicular trajectory will be observed.
Again, this doesn't really address the issue; we started with a scenario where the photon in the clock was traveling a perpendicular line between the midpoints of the mirrors - a perfectly acceptable starting premise. The path length of the photon is given as 2d, twice the distance between the mid-points of the mirror.
You then said that gravity would pull the photon off it's perpendicular trajectory; we can calculate the amount of time dilation using the Pythagorean theorem. Because the mirrors are imparted with the same horizontal velocity as the photon the photon will continue to travel between the mid-points, but the elongated path will mean that the clock ticks slower.
If the trajectory of the photon remains perpendicular then it will mean either one of two things, either the photon will eventually "fall out" of the clock, or no time dilation will occur; bear in mind that there is asymmetry between the reference frames and it is the clock of the observer we are discussing which is time dilated.
The question
The question is, given the non-perpendicular trajectory of the photon, how can it possibly travel between the midpoints of the mirrors?
Relative motion
How do worldtubes which are static in spacetime, which have an absolute existence, give rise to the observation of relative motion, for bars of steel as well as bars of smoke?0 -
Your sloppy reasoning is frustrating. It is still clear that you do not understand what is being said. I feel the only way this can be sorted is if we tackle one issue at a time.There is no express statement about intrinsic motion, as it is a tacit assumption. When we say that we can define a reference frame where the hypothetical observer has a velocity of 2kph, etc. we just shift the implicit assumption of absolute rest to the object with the zero velocity.
The implicit assumption of absolute rest can be deduced from the depicted behaviour of the photon in a light clock.
Also, when Evelyn " arbitrarily choose a reference frame to perform calculations" she calculates that her and Albert's clock is ticking slower than Henry's.
The last paragraph can be dismissed out of hand as an incorrect assertion, begging the question. I.e. When Evelyn arbitrarily chooses a reference frame, she calculates what a hypothetical observer implied by her reference frame measures.
The other paragraphs are strange, as they have absolutely nothing to do with what I said. I showed that any statements I make with an arbitrary reference frame are independent of any metaphysical assertion about intrinsic velocity you make. Therefore, no such assertion is implied by any reference frame. You never respond to this, and instead bring in new arbitrary reference frames, and make the same incorrect assertions about them.
In short, I have exposed your reasoning as bare faced assertions that nobody is compelled to adopt. And, of course, it goes without saying that I have corrected you on these mistakes before.0 -
Your sloppy reasoning is frustrating. It is still clear that you do not understand what is being said. I feel the only way this can be sorted is if we tackle one issue at a time.
The last paragraph can be dismissed out of hand as an incorrect assertion, begging the question. I.e. When Evelyn arbitrarily chooses a reference frame, she calculates what a hypothetical observer implied by her reference frame measures.
The other paragraphs are strange, as they have absolutely nothing to do with what I said. I showed that any statements I make with an arbitrary reference frame are independent of any metaphysical assertion about intrinsic velocity you make. Therefore, no such assertion is implied by any reference frame. You never respond to this, and instead bring in new arbitrary reference frames, and make the same incorrect assertions about them.
In short, I have exposed your reasoning as bare faced assertions that nobody is compelled to adopt. And, of course, it goes without saying that I have corrected you on these mistakes before.
Interesting that you should choose to make such bare assertions.0 -
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Interesting that you should choose to make such bare assertions.
They are not bare assertions. They are demonstrably true. Any statements I construct using an arbitrary reference frame will be independent of any metaphysical assertion you make about intrinsic motion. Therefore, any reference frame does not tacitly assume any state of intrinsic rest.0 -
They are not bare assertions. They are demonstrably true. Any statements I construct using an arbitrary reference frame will be independent of any metaphysical assertion you make about intrinsic motion. Therefore, any reference frame does not tacitly assume any state of intrinsic rest.
Any arbitrary reference frame you construct will be independent of any expressed assertion of absolute rest, but the treatment of physical objects, such as a light clock, demonstrate the implicit assumption of absolute rest.
EDIT: this is the topic of the other thread though
In this thread we are discussing the three physically distinguished scenarios, which are logically necessary to account for relative motion; and, due to their logical necessity, establish the presence of absolute motion.
We are also discussing how a photon which has been pulled off it's perpendicular trajectory can continue to travel between the midpoints of the mirrors of a light clock.
We are also discussing how static world tubes, at angles to each other, can account for relative motion.0 -
Any arbitrary reference frame you construct will be independent of any expressed assertion of absolute rest, but the treatment of physical objects, such as a light clock, demonstrate the implicit assumption of absolute rest.
Physical systems are treated with arbitrary reference frames. Hence, the way physical objects are treated does not imply any statement about intrinsic motion.EDIT: this is the topic of the other thread though
In this thread we are discussing the three physically distinguished scenarios, which are logically necessary to account for relative motion; and, due to their logical necessity, establish the presence of absolute motion.
We are also discussing how a photon which has been pulled off it's perpendicular trajectory can continue to travel between the midpoints of the mirrors of a light clock.
We are also discussing how static world tubes, at angles to each other, can account for relative motion.
If we cannot solve one issue, we cannot solve any. Furthermore, the other issues, particularly the "three scenarios case", depend on the first issue. If you do not accept that coordinate systems do not imply any statement about intrinsic motion, you won't accept that the perceived differences between the scenarios are unphysical.0 -
That is a non-sequitir; the depiction of physical objects, such as light clocks, carry the implicit assumption of absolute rest.Physical systems are treated with arbitrary reference frames. Hence, the way physical objects are treated does not imply any statement about intrinsic motion.
The physicality of the three scenarios is entirely independent of any co-ordinate systems; take away the mathematical reference frames and the underlying physical scenarios remain. The physicial distinction of a treadmill being switched on and being switched off, and the movement of limbs, of a walker, are not dependent mathematical co-ordinates, in any way.If we cannot solve one issue, we cannot solve any. Furthermore, the other issues, particularly the "three scenarios case", depend on the first issue. If you do not accept that coordinate systems do not imply any statement about intrinsic motion, you won't accept that the perceived differences between the scenarios are unphysical.
Furthermore, the logical necessity of one of the three, physically distinguished scenarios to account for relative motion allows us to conclude that absolute motion exists.
In the absence, that is, of an explanation of the extremely mysterious dynamics, which cause 4 dimensional world tubes at angles to each other, which are static in spacetime, to manifest in what we observe as relative motion; and which holds true for bars of steel and bars of smoke.0 -
That is a non-sequitir; the depiction of physical objects, such as light clocks, carry the implicit assumption of absolute rest.
It is not a non-sequitur. We construct reference frames to describe physical systems. These reference frames do not establish any notion of intrinsic motion or intrinsic, absolute rest. Therefore we can completely describe a system without any implicit or explicit, derived or supposed, statements about absolute rest.The physicality of the three scenarios is entirely independent of any co-ordinate systems; take away the mathematical reference frames and the underlying physical scenarios remain. The physicial distinction of a treadmill being switched on and being switched off, and the movement of limbs, of a walker, are not dependent mathematical co-ordinates, in any way.
Furthermore, the logical necessity of one of the three, physically distinguished scenarios to account for relative motion allows us to conclude that absolute motion exists.
In the absence, that is, of an explanation of the extremely mysterious dynamics, which cause 4 dimensional world tubes at angles to each other, which are static in spacetime, to manifest in what we observe as relative motion; and which holds true for bars of steel and bars of smoke.
Take away the reference frames and the physical scenario remains. The three different scenarios you have tendered, however, disappear, since they are artefacts of coordinate systems, and we are left with a coordinate free manifold of events with hyperbolic causal structure between the events, with no a priori notion of past, present, space by itself or time by itself, and hence no notion of intrinsic, absolute motion. Think of it this way: If an object had intrinsic motion, this means it changes its position in space. It is at a location, and then is at another, different location. But to specify locations in this way, you need a coordinate system, so unless you suppose a cosmic coordinate structure exists a priori in nature, intrinsic motion must be an unphysical artefact of an arbitrary reference frame.
And again, there are no mysterious dynamics unless you adopt Lorentzian relativity. In Einstein's relativity, you have well defined, hyperbolic, geometric kinematics. I have explained this several times now and your refusal to accept this simple fact about the structure of relativity is bordering on a childish stubbornness.0 -
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