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Absolute motion
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01-05-2012 5:05am#1This question comes from a discussion on here, and elsewhere, which involved the idea of absolute motion; I just wanted to see what peoples thoughts on the subject were.
Historically, the concept of absolute motion seems to have been thought of as motion relative to an absolute reference frame; where the absolute reference frame is, in practicality, undeterminable. This to me seems to be somewhat of a contradiction in terms, because it suggests that absolute motion is relative i.e. relative to an absolute reference frame.
My understanding of the term "absolute" is
OED - absolute
Philosophy- a value or principle which is regarded as universally valid or which may be viewed without relation to other things:
That is, what is absolute is not relative to something else; so absolute motion would be motion that is not necessarily relative to something else i.e. it is a kind of motion that is not relative. Absolute motion appears to be a perfectly suitable term in that regard.
In the real world
The above is all pretty theoretical, but I think it can be clarified by reference to real world scenarios, to try and give some contextual meaning.
Car
Imagine you are in a car on a long stretch of straight road; the car is stationary such that there is no relative motion between you and the road or the surrounding landscape.
Now, you start the car, put it into gear and press the accelerator, such that relative motion occurs between you and the road, and landscape. The question is, are you actually moving; does it make sense to you to ask the question, are you actually moving; is the rotation of your tyres propelling you forward?
This can be contrasted with the idea that your car is on a giant conveyor belt, and that when your tyres start rotating you actually remain stationary, and it is the road and surrounding landscape that is "doing the moving".
Would you agree that, in this scenario, even if we cannot determine which is actually "doing the moving", we can deduce that, at least, one or the other has to be actually "doing the moving"?
Escalator
Recall a time when you were on an escalator, or even try it the next time you are on an escalator - we'll say an escalator going up, for the sake of clarity.
As you stand on the escalator, are you actually moving; does the idea of "actually moving" make sense to you?
Would you say that you, and the escalator, are actually moving up, as opposed to the universe shifting around you in such a way as to give rise to the relative motion you would expect if you were "actually moving"?
Is it you and the escalator that are "doing the moving" or is it the entire universe?
If you couldn't determine which is the case, would you agree that, at least one of you has to actually be moving, in an absolute sense?
Walking down the road
As you walk down the road, is you that is actually moving, or are you walking on giant treadmill and it is the surrounding landscape that is actually moving? Do those questions make sense to you - even if you took it for granted what the answer was?
Active and Passive
I suppose the distinction I am trying to make is between active and passive relative motion.
When you drive down the road in your car, there is relative motion between you and the road; scientific principles suggest that we cannot determine the absolute nature of the motion of either object/observer, but can we deduce that the motion must be absolute - even if we can't determine who is absolutely moving?
When you walk down the road, relative motion manifests, but does it make sense to say that it is your active moving which is causing the relative motion to manifest, while the road is passively involved? That is, are you actually moving, or is it the road.
If we cannot determine, by experiment, which one is the true state, can we deduce that it must be one or the other?Please read OP first: Does absolute motion exist? 17 votes
No; only relative motion makes sense.0% 0 votesYes; when I walk down the street I am actually moving.100% 17 votes0
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These examples are relative motion to you as an observer.
Take the car example - if you were to imagine looking down on the road system and see all the cars going in different directions, the occupants of each car are still with the universe moving about them - but only from their point of view.
Same can be said with the other examples - the escalator, what about the girl with the pretty smile on the down escalator - is her universe moving differently from yours?0 -
These examples are relative motion to you as an observer.
Take the car example - if you were to imagine looking down on the road system and see all the cars going in different directions, the occupants of each car are still with the universe moving about them - but only from their point of view.
Same can be said with the other examples - the escalator, what about the girl with the pretty smile on the down escalator - is her universe moving differently from yours?
We can still draw the same conclusion, however; in the examples you give, it is either one or the other that has to be moving. For the occupants of other cars who are "still with the universe moving about them", it is the universe which is actually moving. The same for the girl on the escalator; one or the other has to be actually moving, for the relative motion to manifest.
Of course, it isn't possible to determine which is correct, but we can deduce that at least one of them has to be; and by extension, that it is possible for someone to be wrong.0 -
It is your mind that moves? (Old Zen discussion)
http://www.buddhistdoor.com/oldweb/bdoor/archive/zen_story/zen4.htm0 -
Would you agree that, in this scenario, even if we cannot determine which is actually "doing the moving", we can deduce that, at least, one or the other has to be actually "doing the moving"?
Both can be "doing the moving" and everything is moving relative to something else. The car and road move relative to each other.
Roads are not stationary in space and time neither are the buildings that have escalators. If you know as I think you do that these things are not stationary but only stationary relative to an observer then how can you deduce that one or the other be doing the moving and not just moving relative to one another ?0 -
Both can be "doing the moving" and everything is moving relative to something else. The car and road move relative to each other.
Roads are not stationary in space and time neither are the buildings that have escalators. If you know as I think you do that these things are not stationary but only stationary relative to an observer then how can you deduce that one or the other be doing the moving and not just moving relative to one another ?
As you mention above, "both can be doing the moving", but that just compounds the point about the existence of absolute motion; as does saying that roads are not stationary in space, nor the buildings.
If we take the example of a car stopped on a road; you are of course correct to say that the earth might not be stationary in space, but this just means we deduce that the earth is absolutely in motion.
But, it is possible for the earth to be moving through space and the car with it, only for the car to subsequently move along the surface of the earth; again, the deduction is that one of them, at least, is actually moving.
If the car and the earth were at rest relative to each other, then there would be no relative motion between them; in order for relative motion to manifest, at least one of them has to "do the moving", otherwise, they would remain at rest relative to each other.0 -
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No frame of reference is more correct than any other frame of reference, as physics obeys the principle of general covariance. The velocity of an object is a function of the reference frame used. From my frame of reference, a car might be stationary. From the frame of reference of the sun, a car might be travelling at around 30 km/s. From the frame of reference of the galactic centre, the car might be travelling at 220 km/s. No frame of reference is more correct, so no description of the car's velocity is more correct. I.e. The physics is always the same.
So, to take the example tendered here: If we have two objects in motion, relative to each other, we cannot therefore say one reference frame is more correct than the other. I.e. We cannot say one reference frame must be "mistaken". To do so, we would have to assume a state of absolute rest exists, with which to benchmark the motion of the objects, and since no such state is postulated by relativity, or detected by physical evidence, it is a superfluous assumption.0 -
No frame of reference is more correct than any other frame of reference, as physics obeys the principle of general covariance. The velocity of an object is a function of the reference frame used. From my frame of reference, a car might be stationary. From the frame of reference of the sun, a car might be travelling at around 30 km/s. From the frame of reference of the galactic centre, the car might be travelling at 220 km/s. No frame of reference is more correct, so no description of the car's velocity is more correct. I.e. The physics is always the same.
So, to take the example tendered here: If we have two objects in motion, relative to each other, we cannot therefore say one reference frame is more correct than the other. I.e. We cannot say one reference frame must be "mistaken". To do so, we would have to assume a state of absolute rest exists, with which to benchmark the motion of the objects, and since no such state is postulated by relativity, or detected by physical evidence, it is a superfluous assumption.
In your reference frame, where the car is stationary, then we cannot deduce that either one is actually moving, so we can ignore cases where objects remain at rest relative to each other; we only need to consider relative motion between objects to make the deduction. The measurement of the velocity, as such, is immaterial, or secondary at best.
We don't necessarily need for one reference fame to be more correct than any other, we only need to deduce at least one of the objects/observers is in absolute motion; this offers certain deductive consequences which we can take into consideration.
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.
The assumption of absolute rest in relativity is a separate issue entirely.0 -
In your reference frame, where the car is stationary, then we cannot deduce that either one is actually moving, so we can ignore cases where objects remain at rest relative to each other; we only need to consider relative motion between objects to make the deduction. The measurement of the velocity, as such, is immaterial, or secondary at best.
We don't necessarily need for one reference fame to be more correct than any other, we only need to deduce at least one of the objects/observers is in absolute motion; this offers certain deductive consequences which we can take into consideration.
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.
The assumption of absolute rest in relativity is a separate issue entirely.
So long as "absolute motion" does not mean "motion with respect to absolute rest", then there is no major issue. The salient points are
1) Physics is invariant over all reference frames.
2) No reference frame is more or less "true" or "real" than any other.0 -
As you mention above, "both can be doing the moving", but that just compounds the point about the existence of absolute motion; as does saying that roads are not stationary in space, nor the buildings.
If we take the example of a car stopped on a road; you are of course correct to say that the earth might not be stationary in space, but this just means we deduce that the earth is absolutely in motion.
But, it is possible for the earth to be moving through space and the car with it, only for the car to subsequently move along the surface of the earth; again, the deduction is that one of them, at least, is actually moving.
If the car and the earth were at rest relative to each other, then there would be no relative motion between them; in order for relative motion to manifest, at least one of them has to "do the moving", otherwise, they would remain at rest relative to each other.
But all your really doing is saying "motion exists". Which it does and can be observed as relative motion. I dont think you can say absolute motion exists without an absolute frame of reference as motion doesnt exist without a frame of reference. Does it ?0 -
But all your really doing is saying "motion exists". Which it does and can be observed as relative motion. I dont think you can say absolute motion exists without an absolute frame of reference as motion doesnt exist without a frame of reference. Does it ?
To phrase this question slightly differently: "Is there any statements we can make about motion that are independent of any reference frame?"
We can construct statements about the relationship between motion and forces, or we can look at formalisms of classical mechanics that relate motion to energy. I.e. We can build physical laws that are the same for all reference frames, but we cannot say "X is absolutely moving" or "Y is absolutely moving".0 -
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So long as "absolute motion" does not mean "motion with respect to absolute rest", then there is no major issue. The salient points are
1) Physics is invariant over all reference frames.
2) No reference frame is more or less "true" or "real" than any other.
I don't think I'd disagree with any of that, but absolute motion would have certain deductive consequences; not least pertaining to the path length of a photon in a light clock.
That is a separate issue though; the purpose of this thread is just to see if the idea of absolute motion, or "actually moving" makes sense.0 -
That is essentially all that is being said, that "motion exists"; but, more specifically, that a classification of motion exists that doesn't necessarily require a reference frame to define it.But all your really doing is saying "motion exists". Which it does and can be observed as relative motion. I dont think you can say absolute motion exists without an absolute frame of reference as motion doesnt exist without a frame of reference. Does it ?
I would say that absolute motion exists without the need for an absolute frame of reference, because that is what absolute motion is i.e. it isn't relative to anything.
To say that absolute motion requires an absolute reference frame, against which to relate it, is saying that absolute motion is relative motion, or absolute motion is relative (to an absolute reference frame). That would be a contradiction in terms.
Absolute motion would be a simple "yes or no" question; an "either, or" situations:
"is X moving?"
"is Y moving?"
"is X or Y moving?"
Absolute motion will always manifest with relative motion, but there would be a number of possible explanations that can account for the relative motion.
Example
If we take the example of the car on the road, again; when the car starts moving relative to the road, there are 3 main reasons as to why this relative motion can manifest:
1. The earth continued to rotate as normal, and continued, normally, on it's orbit around the sun, and it was the car that actively moved along the surface of the earth.
2. The earth suddenly changed it's rotation, and the turning of the cars wheels lead to the relative motion in a manner similar to someone running the wrong way down an escalator - except with the entire surrounding landscape being tied to the escalator - or akin to someone running on a log spinning in water.
3. Both of the above.
Here we have, again, a case where relative motion is observed, but the active agent, that causes the relative motion between the two objects is different.
It's like being on a train that is stopped, beside another train, in a train station; then the other train pulls out of the station, and for a split second you think that it is your own train that is moving.
You might ask yourself, "are we moving?"; but then you realise, "no it was the other train that was moving". Again, relative motion will occur, but the active role in causing that relative motion is ascribed to either one train, or the other.
Of course, we may not be able to determine which one is actually moving, but we can still deduce that one of them, at least, must be.0 -
We makes statements about motion that are independent of any reference frame on a daily basis.To phrase this question slightly differently: "Is there any statements we can make about motion that are independent of any reference frame?"
When stuck in traffic we say "I'm not moving", or "the traffic isn't moving"; when there is no traffic jam we might say "traffic is moving freely".
We make statements about water and electricity flowing; if we're on a train that is stopped at the train station, and the train beside us starts moving, we often think for a moment "we are moving", only to realise that "it was actually the other train that was moving".
Even though the observed motion is relative in all of these cases, none of the statements make reference to any reference frame; this isn't because relative motion is implied, it's because "actual movement", or absolute motion, is being ascribed to one or the other object
The crux of the issue is that, while we cannot definitively say that "X is absolutely moving", or that "Y is asbolutely moving" we can say that "either X or Y is absolutely moving".We can construct statements about the relationship between motion and forces, or we can look at formalisms of classical mechanics that relate motion to energy. I.e. We can build physical laws that are the same for all reference frames, but we cannot say "X is absolutely moving" or "Y is absolutely moving".0 -
Gosh, this is verbose rubbish. The "stopped" train is moving relative to the moving train. It's isn't stopped from the framework of the other train. That's all. If the "moving" train is travelling at v relative to the stopped train, the stopped train is moving at -v relative to the moving train. Ignoring all other movement - the earth, the sun, the galaxy - both are moving relative to the other, neither is stopped.0
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To make a phenomenological description of movement (how predictable of me) and the example of the train you give. What tells you that it's the other train that's moving and not you? It's the proprioceptive feeling that you are not moving. When you don't feel the push of the train on you you know it's the other train that's movning. You can actually feel yourself moving or at rest. You settle into the objects movement eventually (hence the moon looking like it revolves around us).
In the three original examples you've given this experience occurs where you experience a change in your own acceleration.
And Zeno's arrow paradox for good measure:
1. When the arrow is in a place just its own size, it’s at rest.
2. At every moment of its flight, the arrow is in a place just its own size.
3. Therefore, at every moment of its flight, the arrow is at rest.0 -
The only thing that makes you feel like the train is "moving" is acceleration, or declaration. Trains tend to move a bit choppily, so you feel the "movement" which is small amounts of bumps etc. - effectively acceleration in a different direction. A totally smooth train would not feel like it is moving, transatlantic aeroplanes mid flight don't really fell like they are moving, you feel it on takeoff or landing, or turning. ( Or choppiness). Anything which changes acceleration or direction will be noticed.
Zeno's paradox has also been answered by calculus.
What this means is simple - the "stopped" train is moving relative to the moving train. Both are moving relative to another train, or plane. Neither train is at absolute rest.
When you look out to see the moving train, on your "stopped train", you are moving relative to it. Which means you are moving.0 -
Duggys Housemate wrote: »Zeno's paradox has also been answered by calculus.
How is that? I was under the impression that it couldn't be solved if you assume instants of time have zero duration. The arrow at every instant is moving at 0/0ms.0 -
Forwarned is forearmed, they say; cheers DHDuggys Housemate wrote: »Gosh, this is verbose rubbish.
Duggys Housemate wrote: »The "stopped" train is moving relative to the moving train. It's isn't stopped from the framework of the other train. That's all. If the "moving" train is travelling at v relative to the stopped train, the stopped train is moving at -v relative to the moving train. Ignoring all other movement - the earth, the sun, the galaxy - both are moving relative to the other, neither is stopped.
It's probably easier to think in terms of the two trains starting at rest relative to each other, where v=0.
Then the relative velocity between them increases to some value (v); the question is how/why does the relative velocity increase; how/why is there relative motion between the two trains?0 -
While I would be inclined to agree, I'm not sure if "the science" would, because we supposedly cannot determine, by experiment, if we are moving or not; I'm not sure if this extends to proprioception, or if the equivalence principle would account for the feeling of moving.To make a phenomenological description of movement (how predictable of me) and the example of the train you give. What tells you that it's the other train that's moving and not you? It's the proprioceptive feeling that you are not moving. When you don't feel the push of the train on you you know it's the other train that's movning. You can actually feel yourself moving or at rest. You settle into the objects movement eventually (hence the moon looking like it revolves around us).
In the three original examples you've given this experience occurs where you experience a change in your own acceleration.
But still, the conclusion that could be drawn from that is that either your train or the other train is actually moving - in the example you give above, assuming it doesn't contradict with scientific theory, the conclusion drawn is that your train is actually in motion.
How would the observation of relative motion be accounted for in the context of Zeno's paradox?And Zeno's arrow paradox for good measure:
1. When the arrow is in a place just its own size, it’s at rest.
2. At every moment of its flight, the arrow is in a place just its own size.
3. Therefore, at every moment of its flight, the arrow is at rest.0 -
Then the relative velocity between them increases to some value (v); the question is how/why does the relative velocity increase; how/why is there relative motion between the two trains?
Because one accelerated? Acceleration is a bit more complex in terms of relativeness than velocity. See here
http://www.physicsforums.com/showthread.php?t=592830 -
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The thing is, it is not possible to verify the claim that neither train is at absolute rest, because, as per the Principle of Relativity, the absolute nature of motion cannot be determined. Either train, but not both, could potentially be at absolute rest, it's just that it cannot be determined if that is the case.Duggys Housemate wrote: »What this means is simple - the "stopped" train is moving relative to the moving train. Both are moving relative to another train, or plane. Neither train is at absolute rest.
When you look out to see the moving train, on your "stopped train", you are moving relative to it. Which means you are moving.
But the idea of absolute rest is not necessarily relevant here; we don't need it; we only need to consider relative motion.
When you look out to see the moving train on your "stopped train", there is relative motion; your train is moving relative to the other train, and vice versa.
But if we bring the trains back to the train station, at rest relative to each other; then there are three possible, basic explanations which can account for the relative motion:
1) The other train actually started moving.
2) The entire universe moved while the "moving train" remained stationary
3) Both 1 & 2
If we consider the possible reality of the situation, where the earth is rotating and orbiting the sun, both trains start of at rest on the earth, but both are still actually moving; then one of the trains subsequently starts, actually moving along the surface of the earth.
We cannot determine which train actually started moving, but we can deduce that, at least one of them, actually, started moving.
It really shouldn't take this many words, because it should be fairly self-evident to anyone who has walked down the street, driven in a car, or ever experienced relative motion of any kind; but apparently it's not that straight forward.
It might be worth taking a walk and asking yourself, as you notice the relative motion; is it me that is moving, or am I walking on a giant conveyor belt i.e. is the universe moving around me?
Even if you cannot determine which one it is, you should be able to deduce that it is either one, or the other.0 -
The thing is, it is not possible to verify the claim that neither train is at absolute rest, because, as per the Principle of Relativity, the absolute nature of motion cannot be determined. Either train, but not both, could potentially be at absolute rest, it's just that it cannot be determined if that is the case.
Neither can be at absolute rest. There is nothing, no frame, from which we consider them at absolute rest. If you can think of one, name it.When you look out to see the moving train on your "stopped train", there is relative motion; your train is moving relative to the other train, and vice versa.
Yes, both are moving relative to each other.But if we bring the trains back to the train station, at rest relative to each other;
yes? Both stopped now?then there are three possible, basic explanations which can account for the relative motion:
Relative motion, so apparently not stopped now. YOU mean acceleration here.1) The other train actually started moving.
2) The entire universe moved while the "moving train" remained stationary
3) Both 1 & 2
Again, acceleration, which is measurable, and can be agreed on by both parties is what is happening here. Acceleration can be measured. If I stay still and you accelerate you feel the acceleration and I don't, the physics forum I linked to has some on that. Though not all agree.If we consider the possible reality of the situation, where the earth is rotating and orbiting the sun, both trains start of at rest on the earth, but both are still actually moving; then one of the trains subsequently starts, actually moving along the surface of the earth.
WEll, yes?We cannot determine which train actually started moving, but we can deduce that, at least one of them, actually, started moving.
We can deduce which one started moving, because acceleration is not like velocity. Acceleration is a change in velocity. the one which started moving accelerated. YOu are confusing accelerating with velocity.It really shouldn't take this many words,
thats rightbecause it should be fairly self-evident to anyone who has walked down the street, driven in a car, or ever experienced relative motion of any kind; but apparently it's not that straight forward.
It might be worth taking a walk and asking yourself, as you notice the relative motion; is it me that is moving, or am I walking on a giant conveyor belt i.e. is the universe moving around me?
Or I could stand still and look at the Sun and say is it slowly moving across the sky, as I stay still, or am I on something which is rotating at 700 to 900 miles to hour? If I were to rely on self-evidence it would be the former.
Sure, there is barely a breeze.0 -
Duggys Housemate wrote: »Because one accelerated? Acceleration is a bit more complex in terms of relativeness than velocity. See here
http://www.physicsforums.com/showthread.php?t=59283
Why would one of them accelerating cause relative motion to manifest?0 -
The point was that neither of them needs to be at absolute rest; it isn't necessary for the purpose of the deduction.
But further, the earth could be at absolute rest, we just have no way of telling if that is the case.
No, we have a way. Since we can make any object the reference frame which appears to be at rest ( which you are doing with the "stopped" train), and this applies to any object in the universe, therefore we cannot say any object is at absolute rest. All are moving relative to each other.
There is no absolute rest. This seems simple to me, I don't get the difficulty ( I think there are two types of intelligence on this thread. Scientific and literate).How/why does the acceleration of one train cause relative motion between the two trains?
Because acceleration increases the velocity of one of them relative to the other. Again, simples.
You seem to be suggesting there is a deeper meaning to all of this, but I am not really understanding the confusion.0 -
The point was that neither of them needs to be at absolute rest; it isn't necessary for the purpose of the deduction.Duggys Housemate wrote: »Neither can be at absolute rest. There is nothing, no frame, from which we consider them at absolute rest. If you can think of one, name it.
But further, the earth could be at absolute rest, we just have no way of telling if that is the case.
We're agreed on this at least.Duggys Housemate wrote: »Yes, both are moving relative to each other.
That depends on whether or not the earth is actually moving; but it isn't necessary to consider that for the purpose of the deduction, we only need to consider the relative motion of the trains.Duggys Housemate wrote: »yes? Both stopped now?
By stopped I simply mean at rest relative to the earth, in the station.
Yes, apologies, I should have added the intermediary step of one train leaving the station.Duggys Housemate wrote: »Relative motion, so apparently not stopped now. YOU mean acceleration here.
Also, yes, one of the trains accelerates; but that isn't necessarily the issue.
How/why does the acceleration of one train cause relative motion between the two trains?Duggys Housemate wrote: »Again, acceleration, which is measurable, and can be agreed on by both parties is what is happening here. Acceleration can be measured. If I stay still and you accelerate you feel the acceleration and I don't, the physics forum I linked to has some on that. Though not all agree.
That just compounds the idea of absolute motion, becaue the earth is actually rotating and actually orbiting the sun, as opposed to the other way around.Duggys Housemate wrote: »WEll, yes?
The equivalence principle would suggest that we can't determine which one started moving, because the acceleration that is experienced could be a gravitational field; it is possible that both were free-falling in a gravitational field and hence experienced no gravity; one of them could then have used their engines (or something might have happened the earth) to cause them to remain stationary in a gravitational field, and hence experience what they think is acceleration.Duggys Housemate wrote: »We can deduce which one started moving, because acceleration is not like velocity. Acceleration is a change in velocity. the one which started moving accelerated. YOu are confusing accelerating with velocity.
Of course, given this scenario, we can still conclude that either one or the other actually moved, or was moving.
Indeed you could, and under relativity this perspective is just as correct as a reference frame where the earth is rotating and orbiting the sun; but still, even given that scenario we can still deduce that it is either the earth that is actually moving, or it is the sun, or indeed, both might actually be moving, as I would be more inclined to think myself.Duggys Housemate wrote: »Or I could stand still and look at the Sun and say is it slowly moving across the sky, as I stay still, or am I on something which is rotating at 700 to 900 miles to hour? If I were to rely on self-evidence it would be the former.
Sure, there is barely a breeze.0 -
To suggest that we have a way of determining the absolute nature of motion is counter to the scientific intelligence you believe is in this thread; i.e. to suggest we have a way of determining if an object is at absolute rest or not, is not supported by scientific evidence. The test of the principle of relativity states this quite explicitly.Duggys Housemate wrote: »No, we have a way. Since we can make any object the reference frame which appears to be at rest ( which you are doing with the "stopped" train), and this applies to any object in the universe, therefore we cannot say any object is at absolute rest. All are moving relative to each other.
There is no absolute rest. This seems simple to me, I don't get the difficulty ( I think there are two types of intelligence on this thread. Scientific and literate).
To re-iterate, the earth could be at absolute rest, we just have no way of telling if it is or not. I think you may, also, have misunderstood what was meant by the "stopped" train, although that is largely due to my ambiguity, for which I apologise.
How can acceleration increase the velocity of one of them relative to the other?Duggys Housemate wrote: »Because acceleration increases the velocity of one of them relative to the other. Again, simples.
That is because the confusion is on your part; it might be worth taking a quick walk outside, or even just down a corridor; where you won't be using mathematical reference frames, all you will have is empircal experience.Duggys Housemate wrote: »You seem to be suggesting there is a deeper meaning to all of this, but I am not really understanding the confusion.
Take a walk down the hall, notice the relative motion and ask yourself are you actually moving, or is the hall behaving like a treadmill?
Apologies if I'm being too presumptuous that you've been on a treadmill before.0 -
Just on the link to the thread you posted; am I right in saying that the term "absolute" is taken to mean "agreed on by everyone", if so, then that isn't necessarily what "absolute" means; there are different terms in the english language for that.
Insofar as acceleration is a measured quanity, it is relative, because measurement is, by it's very nature, relative.
This might be what you mean by scientific and literate intelligence, but where science uses the english language, it is probably better to try and use it more scientifically i.e. precisely.0 -
Take a walk down the hall, notice the relative motion and ask yourself are you actually moving, or is the hall behaving like a treadmill?
Alright I am out - as if this is the best that philosophy can do it should be shut down and tossed out of the universities, I hope you are not an standard practicioner. YOu barely understand the terms you are talking about, and you answer back with the same logic, despite it being explained before. I would prefer to pluck my eyebrows out one by one than deal with this level of "knowledge".
Your reference to "common sense" perceptions of motion is meaningless. Humans are designed to perceive things that helped our ancestors.
For what it is worth it doesn't matter whether I am moving, or the hall is a treadmill. Either would do for the mathematics of relative motion, or indeed common sense.
It would be better to put me on a car or some externally powered machine ( otherwiseI would I would be applying energy to pedal or walk).
In this case were the hall moving backwards at a constant velocity I could not tell the difference between that and going forward. This is, in effect, what cartoons and games do. In 2d games ( and cartoons) the landscape scrolls left, and the character stays centred but apparently moving right. In 3d games your character stays centred, and the universe moves around you - that is how it modelled. Press forward, and the physics of the game redraws the road you are on so objects ahead move towards you, meaning they are redrawn bigger. In the logic of the game, moving forward is the same mathematically as bringing the landscape ahead backwards. As we would expect.
Now, back with me to science fora.0 -
The issue probably lies in the simplicity of it.Duggys Housemate wrote: »Alright I am out - as if this is the best that philosophy can do it should be shut down and tossed out of the universities, I hope you are not an standard practicioner. YOu barely understand the terms you are talking about, and you answer back with the same logic, despite it being explained before. I would prefer to pluck my eyebrows out one by one than deal with this level of "knowledge".
The error lies in thinking that it has been satisfactorily explained; ultimately the explanation always comes back to "relative motion causes relative motion", which isn't a sufficient explanation.
As outlined, there are three scenarios which can result in relative motion; all of them involve active movement of one object or another i.e. an object has to actually move i.e. an object has to move absolutely.
Don't be confused by the term "common sense", I just mean that it is blindingly obvious.Duggys Housemate wrote: »Your reference to "common sense" perceptions of motion is meaningless. Humans are designed to perceive things that helped our ancestors.
The error lies in thinking that it doesn't matter; while the mathematics might be the same, there are deductive consequences which apply to the phyiscal world that the mathematics don't seem to highlight.Duggys Housemate wrote: »For what it is worth it doesn't matter whether I am moving, or the hall is a treadmill. Either would do for the mathematics of relative motion, or indeed common sense.
It doesn't matter either way; the basic question is, are you capable of motion?Duggys Housemate wrote: »It would be better to put me on a car or some externally powered machine ( otherwiseI would I would be applying energy to pedal or walk).
You seem to be missing the point; that you cannot tell the difference is entirely immaterial, that there is a difference, by your own admission, is the point.Duggys Housemate wrote: »In this case were the hall moving backwards at a constant velocity I could not tell the difference between that and going forward. This is, in effect, what cartoons and games do. In 2d games ( and cartoons) the landscape scrolls left, and the character stays centred but apparently moving right. In 3d games your character stays centred, and the universe moves around you - that is how it modelled. Press forward, and the physics of the game redraws the road you are on so objects ahead move towards you, meaning they are redrawn bigger. In the logic of the game, moving forward is the same mathematically as bringing the landscape ahead backwards. As we would expect.
Now, back with me to science fora.
The computer game example is a useful one, cheers. Again, however, it simply re-iterates the point, either you are actually moving, or the scenery is.0 -
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We makes statements about motion that are independent of any reference frame on a daily basis.
When stuck in traffic we say "I'm not moving", or "the traffic isn't moving"; when there is no traffic jam we might say "traffic is moving freely".
We make statements about water and electricity flowing; if we're on a train that is stopped at the train station, and the train beside us starts moving, we often think for a moment "we are moving", only to realise that "it was actually the other train that was moving".
Even though the observed motion is relative in all of these cases, none of the statements make reference to any reference frame; this isn't because relative motion is implied, it's because "actual movement", or absolute motion, is being ascribed to one or the other object
All of those statements make reference to a frame of reference. For example, "It was actually the other train that was moving" is from the reference frame of the earth. "We are not moving" is from the reference frame of the train. Water and electricity flow in the reference frame of the circuit. "Traffic is moving freely" in the reference frame of the road/earth.The crux of the issue is that, while we cannot definitively say that "X is absolutely moving", or that "Y is absolutely moving" we can say that "either X or Y is absolutely moving".
If by this you mean "There is no reference frame which labels both X and Y as stationary." you are correct. You cannot, however, extend this to "At least one of X or Y must be moving with respect to absolute rest." without implicitly assuming absolute rest exists.0
This discussion has been closed.
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