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Thread: All Motion is Relative?

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    Quote Originally Posted by Le Repteux View Post
    Hi Markbo,

    And what if light was not only an indicator of motion for us, but also for those who produce it: the atoms? If it gives information for the direction and speed of a body to us, why couldn't it give it also to the atoms? After all, they are the ones who obey to the forces that induce motion to us, no? From the point of view of an atom, what is relative motion? If they depend only on light to execute their motions, wouldn't light represent an absolute reference for all of them?
    There is no such thing as "absolute motion".
    Atoms do not "rely on light" .
    Please stop pushing fringe ideas into the main forum, you already have your dedicated thread in Pseudoscience.
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    Quote Originally Posted by marcbo View Post
    Quote Originally Posted by Implicate Order View Post
    No probs marcbo. That time you spent in Galt's gulch was worth it
    .. as a visit to the gulch would be liable to make one more Newtonian than Einsteinian, however, no comment :-))

    --------------------------------------------------------------------------------------------------------------

    Moving along with our little thought experiment, IO, it seems clear now, that what you and Janus are saying is that the photon behaves like a mass particle, ie, in principle, it behaves the same as the bullet.

    The only issue remaining to be resolved in my mind then, is .. why ?

    Put it this way. IF the emitter (laser gun) was at rest in my frame the emitted photon would travel A - B (vertical), but if it travelled A - C, as you say it would, the ONLY reason .. the ONLY difference, can be that it had horizontal motion as well as vertical motion.

    So it is behaving like a mass particle. WHY ?

    We can discount any rectilinear motion of the emitter and say the photon was unaffected by it - ie, if the emitter was travelling at 1/2 c in the direction of the emitted photon, we would of course, say this was of no effect and the photon would still travel at c. Speed of light being independent of source motion.

    So why discount the vertical motion but NOT the horizontal one ?
    Could we say that a photon (at rest) has no mass and therefore is unaffected by transverse motions? It's mass is derived from the kinetic energy of "straight forward motion @ c" and is the only active component of movement of a photon. Only after the photon is emitted does it gain it's mass (instantly) and may be subject to gravitaty of a massive object which curves spacetime itself, even as the photon continues to follow a straight path along the spacetime curvature.

    Also, I have a question about "aberration". Should we not say "apparent aberration?". Perhaps somewhat similar to "apparent speed" of an airplane flying against a strong head wind, while it "true speed" as measured from the earth's surface shows a much slower progress. Or a boat travelling @ 5 knots against a stream running down @ 5 knots. The apparent speed of the boat is 5 knots (by the knot meter), but the boat remains stationary in relation to the shore.

    The photon has no such restrictions, it always travels in a straight line @ c, regardless of the motion of the emitter?
    Any counter movements would affect the wavelength of the photon but not its path or speed.

    Note: these are probative questions, not statements of fact.
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    Quote Originally Posted by Write4U View Post

    Could we say that a photon (at rest) has no mass and therefore is unaffected by transverse motions?
    No, you cannot say that since it is not true. Though the photon has no rest mass, I have shown, IN THIS THREAD, at least twice, that its motion is affected by the frame of reference. The law of relativistic speed composition explains the effect.

    Here is the explanation, one more time. It is a general explanation. Assume that a photon has velocity in frame S. In frame S', moving at constant speed v wrt S, the relativistic speed composition says that light velocity has the components:







    If then:



    (Einstein's second postulate confirmed)




    If then:



    (the "light clock")

    In ALL cases
    Last edited by Howard Roark; October 6th, 2014 at 06:29 PM.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    Could we say that a photon (at rest) has no mass and therefore is unaffected by transverse motions?
    No, you cannot say that since it is not true. Though the photon has no rest mass, I fave shown, IN THIS THREAD, at least twice, that its motion is affected by the frame of reference. The law of relativistic speed composition explains the effect.
    ok, but relativistic frames of reference are from points of observation and presents an "appearance" of change, while each photon travels undisturbed at c.

    question: do two photons travelling in opposite directions approach each other at 2c or does time dilation/compression play a factor?
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    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    Could we say that a photon (at rest) has no mass and therefore is unaffected by transverse motions?
    No, you cannot say that since it is not true. Though the photon has no rest mass, I fave shown, IN THIS THREAD, at least twice, that its motion is affected by the frame of reference. The law of relativistic speed composition explains the effect.
    ok, but relativistic frames of reference are from points of observation and presents an "appearance" of change, while each photon travels at c.
    Nothing in relativity is "appearance" since all effects (with the exception of RoS) are measurable.

    question: do two photons travelling in opposite directions approach each other at 2c ?
    This is called "closing speed" and it is indeed 2c. Whether the photons approach each other head on or move away from each other in opposite directions. Nothing to do with relativistic speed composition, it is a totally different effect.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    Could we say that a photon (at rest) has no mass and therefore is unaffected by transverse motions?
    No, you cannot say that since it is not true. Though the photon has no rest mass, I fave shown, IN THIS THREAD, at least twice, that its motion is affected by the frame of reference. The law of relativistic speed composition explains the effect.
    ok, but relativistic frames of reference are from points of observation and presents an "appearance" of change, while each photon travels at c.
    Nothing in relativity is "appearance" since all effects (with the exception of RoS) are measurable.
    So is the boat speed measurable even as it makes no progress against the flow of the river. IMO, Relativity only exist if there are frames of reference. Remove the observer and the ability to measure relativistic appearances disappears.

    I understand relativity (basically), but what we observe are apparent "effects", but does not affect or reflect the "true" behavior of the photon.

    In photography, when taking a picture while panning (following) a moving object, the stationary background will become smeared. OTOH, if we take a picture from a stationary camera, the background will be sharp but the moving object will be smeared (blurred). These are "effects" presented to the observer, but do not reflect reality, where both background and moving object are sharply defined if observed seperately.
    Last edited by Write4U; October 6th, 2014 at 07:00 PM.
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    Quote Originally Posted by Write4U View Post

    I understand relativity (basically), but what we observe are apparent "effects", but does not affect or reflect the "true" behavior of the photon.
    Based on what you persist in writing, you don't. Have fun.
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    Quote Originally Posted by Write4U View Post
    IMO, Relativity only exist if there are frames of reference. Remove the observer and the ability to measure relativistic appearances disappears.
    What relativity does is describe the relationship between frames of reference in space-time; it relates measurements taken by different observers to one another. If you have only a single ruler or clock at rest together with you, it is true that for this reason you can never observe any relativistic effects. However, once more than one frame of reference is involved, the relativistic effects introduced by their relationship are quite real, and not just apparent; for example, a cosmic ray muon actually does reach the surface of the Earth and gets physically detected here, even though without relativity it would decay long before it gets down here. Reality is always what ruler/clocks/accelerometers/detectors physically measure.

    As for the camera example - the "smearing" is a result of limitations in how the camera works, not a property of what is being photographed. Relativity on the other hand deals directly with the real world - the muon is either detected or it is not, there is no uncertainty or "smearing" in this, and all observers agree to the outcome, including a hypothetical "muon observer" himself. Hopefully I am making sense ?
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Le Repteux View Post
    Hi Markbo,

    And what if light was not only an indicator of motion for us, but also for those who produce it: the atoms? If it gives information for the direction and speed of a body to us, why couldn't it give it also to the atoms? After all, they are the ones who obey to the forces that induce motion to us, no? From the point of view of an atom, what is relative motion? If they depend only on light to execute their motions, wouldn't light represent an absolute reference for all of them?
    There is no such thing as "absolute motion".
    I said absolute reference.

    Atoms do not "rely on light" .
    What is a graviton if not light? What is a virtual photon if not light?

    Please stop pushing fringe ideas into the main forum, you already have your dedicated thread in Pseudoscience.
    The question from the topic is already fringe, it induced me in error, but my question is nevertheless a physical one: if all the atoms of the universe execute their motion while getting their information from the same discrete light pulses, wouldn't these light pulses be a common reference for them, thus an absolute reference since they never change direction or frequency once emitted?
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    Quote Originally Posted by Le Repteux View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Le Repteux View Post
    Hi Markbo,

    And what if light was not only an indicator of motion for us, but also for those who produce it: the atoms? If it gives information for the direction and speed of a body to us, why couldn't it give it also to the atoms? After all, they are the ones who obey to the forces that induce motion to us, no? From the point of view of an atom, what is relative motion? If they depend only on light to execute their motions, wouldn't light represent an absolute reference for all of them?
    There is no such thing as "absolute motion".
    I said absolute reference.
    There is no such thing. This was know for the last 110 years.


    Atoms do not "rely on light" .
    What is a graviton if not light? What is a virtual photon if not light?
    Notwithstanding the non-sequitur, gravitons aren't "light".

    Please stop pushing fringe ideas into the main forum, you already have your dedicated thread in Pseudoscience.
    The question from the topic is already fringe, it induced me in error, but my question is nevertheless a physical one: if all the atoms of the universe execute their motion while getting their information from the same discrete light pulses, wouldn't these light pulses be a common reference for them, thus an absolute reference since they never change direction or frequency once emitted?
    No, it wouldn't. And yes, you are trying to hijack this thread with your fringe theory. You already have your dedicated thread in "Pseudoscience" on the subject. Keep it there.
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    This question is about the way atoms use information from other atoms to execute their different motions, it is not about the way they execute them.
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    Quote Originally Posted by Le Repteux View Post
    This question is about the way atoms use information from other atoms to execute their different motions, it is not about the way they execute them.
    Yes, you have your own thread on this fringe idea of yours, stop hijacking this one. Keep your pseudoscience where it belongs: in Pseudoscience.
    Last edited by Howard Roark; October 7th, 2014 at 09:50 AM.
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    Tell me how an atom from the earth can execute its gravitational motion with the atoms from the moon with no information to do so.
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    Quote Originally Posted by Le Repteux View Post
    Tell me how an atom from the earth can execute its gravitational motion with the atoms from the moon with no information to do so.
    Move your question in your dedicated thread in Pseudo and I will answer it. Stop hijacking other people's threads (with your fringe nonsense).
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    Quote Originally Posted by Le Repteux View Post
    Tell me how an atom from the earth can execute its gravitational motion with the atoms from the moon with no information to do so.
    They follow geodesics in space-time, as simple as that. Static gravitation does not require the exchange of information, any more than longitudinal lines require the exchange of information in order to intersect at the pole; it is just a consequence of the underlying geometry. That is why static gravitation can act instantaneously, whereas changes in gravity propagate at the usual speed of light, as expected. All of this can, of course, be made mathematically rigorous.

    But I agree with Howard - please keep your personal theories contained in your dedicated thread.
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    Here is the OP:
    Quote Originally Posted by ScienceNoob
    Is there any number for a "true" speed.
    Everyone knows that even if you are standing still on earth you are flying around in orbit of the sun at Xm/s. This galaxy is also moving faster and faster according to what I have read about expanding universe.
    So how would you measure the speed of earth itself total, not in reference to the sun, not in reference to the galaxy?
    Is there a unit for this? You would need a "center" of the universe to do that I think.
    My question is less fringe than this one, but it is also a question about a reference for motion, not only for observing motion though, but also to execute it.
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    Quote Originally Posted by Le Repteux View Post
    Here is the OP:
    Quote Originally Posted by ScienceNoob
    Is there any number for a "true" speed.
    Everyone knows that even if you are standing still on earth you are flying around in orbit of the sun at Xm/s. This galaxy is also moving faster and faster according to what I have read about expanding universe.
    So how would you measure the speed of earth itself total, not in reference to the sun, not in reference to the galaxy?
    Is there a unit for this? You would need a "center" of the universe to do that I think.
    My question is less fringe than this one, but it is also a question about a reference for motion, not only for observing motion though, but also to execute it.
    The fact that the OP is fringe is not an excuse for you to add your fringe contributions in the attempt of hijacking the thread. It is bad enough that "marcbo" attempted to hijack it with his fringe ideas, please stop adding your fringe ideas. Come to think of it, this whole thread belongs in "Pseudo".
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    I thought faster than you this time!
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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by Le Repteux View Post
    Tell me how an atom from the earth can execute its gravitational motion with the atoms from the moon with no information to do so.
    They follow geodesics in space-time, as simple as that.
    Where is the information written in that space-time continuum? In the sky?

    But I agree with Howard - please keep your personal theories contained in your dedicated thread.
    This is not a question about the small steps, but I agree with Howard, this topic belongs in fringe science topics.
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    Quote Originally Posted by Le Repteux View Post
    Quote Originally Posted by Markus Hanke View Post
    But I agree with Howard - please keep your personal theories contained in your dedicated thread.
    This is not a question about the small steps, but I agree with Howard, this topic belongs in fringe science topics.
    So stick to the fringe part of the forum, please.
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    It's not "fringe" it's the clippings on the barbershop floor soon to he swept up and thrown in Trash...
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    Quote Originally Posted by PhDemon View Post
    It's not "fringe" it's the clippings on the barbershop floor soon to he swept up and thrown in Trash...
    Very accurate description.
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    Hair clips are cleaner than bullshit. Tired of cleaning your hands, Howard?
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    Quote Originally Posted by Vexspits View Post
    Quote Originally Posted by marcbo View Post
    Quote Originally Posted by Vexspits View Post
    We have two different concepts under the umbrella of “time”. 1) Measured time: a motion relative to an observer used as a standard to compare to any given motion. 2) Change: the changing geometrical relations of all material bodies. “We use the same word to refer to one or the other, never really making a distinction between the two (Payette; Ghost in The Time Machine; p.16).So in the cases you are trying to understand, just keep this in mind: no matter how you measure the velocity of light to determine its “velocity”—in other words: no matter what standard motion relative to you as an observer you use—you always get the same result: you measure the speed of light to be c. "This is not up for debate!"(Payette; p.15). However, it doesn’t mean that there is no difference between case 1) light travelling toward an object that is stationary relative to the source, and 2) light travelling toward an object that is moving away from that source. There will be more change in case # 2, regardless of the fact that an observer located on the object in either scenario would measure the velocity of light to be the same. The “true” velocity you are after can be understood in this way, but only in this way; not from the operational standpoint, not from the standpoint of number, or as Einstein might have put it: not from the point of view of “time in physics”.
    Hi Vexspits. You joined 2011 and only six posts ? Wow .. this one must have been important for you :-)

    A definition of time has always been a vexing issue to me - it always seems circular, as I have discussed with others in other threads.

    In any case, I am happy to go with the prevailing scientific definition, which I believe, goes something like ..

    "time is that which is meaasured by clocks"
    (though I paraphrase - it could be a worded little differently to that).
    Hi Marcbo. Not that important; the science forum "wished me" a happy birthday so I decided to peruse the physics section. As for "time is what a clock measures" that is exactly what item 1) above points to: Measured time:a motion relative to an observer used as a standard to compare to any given motion. That is what a clock is: a standard motion used to compare to other motion. In the same way we use a standard distance to measure distance.
    Hi Vexspits, OK. And I think we've canvassed it in the same manner with Write4U, above.
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    Quote Originally Posted by Le Repteux View Post
    Hi Markbo,

    And what if light was not only an indicator of motion for us, but also for those who produce it: the atoms? If it gives information for the direction and speed of a body to us, why couldn't it give it also to the atoms? After all, they are the ones who obey to the forces that induce motion to us, no? From the point of view of an atom, what is relative motion? If all atoms would depend only on light to execute their motions, wouldn't light represent an absolute reference for all of them?
    No sure about this one, other than to say I understood that light travels at c for all observers, in all frames, etc. I hope others have been able to help you.
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    Quote Originally Posted by Write4U View Post
    Could we say that a photon (at rest) has no mass and therefore is unaffected by transverse motions? It's mass is derived from the kinetic energy of "straight forward motion @ c" and is the only active component of movement of a photon. Only after the photon is emitted does it gain it's mass (instantly) and may be subject to gravitaty of a massive object which curves spacetime itself, even as the photon continues to follow a straight path along the spacetime curvature.
    A photon at rest ? That's a new one to me. I always thought a photon WAS light (or bits of light) so always travelling at c.

    Also, I have a question about "aberration". Should we not say "apparent aberration?". Perhaps somewhat similar to "apparent speed" of an airplane flying against a strong head wind, while it "true speed" as measured from the earth's surface shows a much slower progress. Or a boat travelling @ 5 knots against a stream running down @ 5 knots. The apparent speed of the boat is 5 knots (by the knot meter), but the boat remains stationary in relation to the shore.
    Yes, well, that's the point I raised earlier when aberration was mentioned. It hardly matters to the photon whether my view of it is aberrated or altered or restricted in any way. I't still going to do what it's going to do.

    The photon has no such restrictions, it always travels in a straight line @ c, regardless of the motion of the emitter?
    Any counter movements would affect the wavelength of the photon but not its path or speed.
    Note: these are probative questions, not statements of fact.
    I agree. Therefore if the emitter had any transverse motion, the photon would not follow it. AKA first rate test for absolute motion. It's that simple. But of course, I can understand that folk who have spent their entire lives believing otherwise would have great difficulty in seeing this. Much earlier in this thread, it was said that the shackles of Newtonianism are very hard to break. Imagine then, how much MUCH harder it would be to break the shackles of Einsteinism, if it was neccessary to do so.
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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by Write4U View Post
    IMO, Relativity only exist if there are frames of reference. Remove the observer and the ability to measure relativistic appearances disappears.
    What relativity does is describe the relationship between frames of reference in space-time; it relates measurements taken by different observers to one another. If you have only a single ruler or clock at rest together with you, it is true that for this reason you can never observe any relativistic effects. However, once more than one frame of reference is involved, the relativistic effects introduced by their relationship are quite real, and not just apparent; for example, a cosmic ray muon actually does reach the surface of the Earth and gets physically detected here, even though without relativity it would decay long before it gets down here. Reality is always what ruler/clocks/accelerometers/detectors physically measure.

    As for the camera example - the "smearing" is a result of limitations in how the camera works, not a property of what is being photographed. Relativity on the other hand deals directly with the real world - the muon is either detected or it is not, there is no uncertainty or "smearing" in this, and all observers agree to the outcome, including a hypothetical "muon observer" himself. Hopefully I am making sense ?
    Thanks Markus, for responding seriously to my questions.

    If I may be allowed to probe a little further. Assuming that the muon travels @ c, but decays in milliseconds, would it be logical to assume that the observed muon has travelled all the way from say, the sun, or is it possible that the muon was formed from other cosmic radiation, an instant before it strikes the earth?
    As I understand it, muons can form from other forms of cosmic radiation. In fact, the following illustrations assume the formation of a muon at a height of 10 km above the earth. This I can logically accept as a muon is able to traverse that distance before decaying.
    Muon Experiment in Relativity

    Moreover, a muon has a "rest mass" and decay relatively slowly compared to other particles. This line from wiki peaked my interest.
    As an example, so-called "secondary muons", generated by cosmic rays hitting the atmosphere, can penetrate to the Earth's surface, and even into deep mines.
    Muon - Wikipedia, the free encyclopedia

    And lastly, I understand using the muon itself as an observer and as such it would experience the effects of relativity such as time dilation, because (as I understand it) its inherent clock runs slower than inherent clocks of other particles, which I assume is the reason why it decays slower than other particles.

    But I believe that my example of the camera is an illustration of a form of extreme time dilation by the shutter speed of the camera. I thought this might be used as an amplification of the relativistic effects when there are 2 (3?) frames of reference (camera, moving object of observation and/or background)

    My main point was to illustrate that relativistic actions in nature is not always what we observe. Again I cite the boat moving at a speed equal to the speed of the river and apparently not moving at all as seen by an observer on the shore.

    This why my statement about "apparent speed" (as observed from the shore) and "true speed" (as observed from the knotmeter on the boat) which IMO, is an example of possible problems with our "observation" of relativity.
    Last edited by Write4U; October 7th, 2014 at 08:39 PM.
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    Quote Originally Posted by Le Repteux View Post
    Hair clips are cleaner than bullshit. Tired of cleaning your hands, Howard?
    He cleans his hands often - by morphing to another name, other forums, etc.

    I find it best to keep him on ignore. He is a serial pest and bully, and has been banned and suspended multiple times on this and other forums for his abusive manner. If you search around this and other similar science forums, you will see ample evidence of this. Presently he's here in the guise of Howard Roak, but also look for 'xyzt' here and elsewhere, and 'tach' in sciforums, where you will see his posting style, content and syntax is the same as it is here. His performance there is particularly interesting (wink wink, tach) !

    As I said, best ignored !!!
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    Markus, Write4U .. VERY interesting last couple of (your) posts. Will dowload to read .. slowly ..

    Great work !
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    Quote Originally Posted by Write4U View Post



    And lastly, I understand using the muon itself as an observer and as such it would experience the effects of relativity such as time dilation, because (as I understand it) its inherent clock runs slower than inherent clocks of other particles,
    No, it doesn't. The proper time always runs at the same rate : one second per second. You are making a second error, it is not the "muon itself as an observer ...it would experience the effects of time dilation". From the perspective of a frame comoving with the muon , there is no time dilation. There is length contraction of the path, though. The time dilation is measured from the perspective of an observer on the ground.


    My main point was to illustrate that relativistic actions in nature is not always what we observe.
    This is not a scientific point of view.

    Again I cite the boat moving at a speed equal to the speed of the river and apparently not moving at all as seen by an observer on the shore.
    This is called "relativity", so, in effect you are denying relativity (after grossly misinterpreting it in the prior paragraph). Speed is a frame-variant quantity.


    This why my statement about "apparent speed" (as observed from the shore) and "true speed" (as observed from the knotmeter on the boat) which IMO, is an example of possible problems with our "observation" of relativity.
    The correct terms are "proper speed" and "coordinate speed". Mainstream scientists have no problem with "observation of relativity", fringers like "marcbo" do. Try to not become like him.
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    Quote Originally Posted by marcbo View Post
    Quote Originally Posted by Le Repteux View Post
    Hair clips are cleaner than bullshit. Tired of cleaning your hands, Howard?
    He cleans his hands often - by morphing to another name, other forums, etc.

    I find it best to keep him on ignore.
    You are under the delusion that if you covered your eyes and you stuck your fingers in your yeas, the crankeries that you keep posting go unobserved. Yes, they become invisible to you but everyone else can still see them.

    He is a serial pest and bully,
    Pointing out the fringe in your posts doesn't make me a bully.


    Presently he's here in the guise of Howard Roak, but also look for 'xyzt' here and elsewhere, and 'tach' in sciforums, where you will see his posting style, content and syntax is the same as it is here. His performance there is particularly interesting (wink wink, tach) !

    As I said, best ignored !!!
    I asked you before: who is "tach"? I have never posted on sciforums (way too many cranks and too little physics) but it appears that , whoever this "yach" is, he must have burned your ass, exposing you for your deeply crackpot posts. Did you post on sciforums? Under what nik?
    Last edited by Howard Roark; October 7th, 2014 at 10:26 PM.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    And lastly, I understand using the muon itself as an observer and as such it would experience the effects of relativity such as time dilation, because (as I understand it) its inherent clock runs slower than inherent clocks of other particles,
    No, it doesn't. The proper time always runs at the same rate : one second per second. You are making a second error, it is not the "muon itself as an observer ...it would experience the effects of time dilation". From the perspective of a frame comoving with the muon , there is no time dilation. There is length contraction of the path, though. The time dilation is measured from the perspective of an observer on the ground.
    Thus this quote is incorrect?
    Earlier experiments on muons produced by cosmic rays found their half-lives to be dependent on distance traveled through the atmosphere; they also exhibited relativistic time dilation.
    Wolfram Demonstrations Project

    My main point was to illustrate that relativistic actions in nature is not always what we observe.
    This is not a scientific point of view.
    But is the statement incorrect?

    Again I cite the boat moving at a speed equal to the speed of the river and apparently not moving at all as seen by an observer on the shore.
    This is called "relativity", so, in effect you are denying relativity (after grossly misinterpreting it in the prior paragraph). Speed is a frame-variant quantity.
    Interesting that you would use the term "in effect I am denying relativity", which proves my point of "apparent" and "true". I have never denied relativity anywhere in my posts. Apparently to you I have, but you have no proof I said that anywhere, ever.

    This why my statement about "apparent speed" (as observed from the shore) and "true speed" (as observed from the knotmeter on the boat) which IMO, is an example of possible problems with our "observation" of relativity.
    The correct terms are "proper speed" and "coordinate speed". Mainstream scientists have no problem with "observation of relativity", fringers like "marcbo" do. Try to not become like him.
    Sailors and airplane pilots might have some problems with those terms. They always use the terms apparent (wind) speed and true (wind) speed.
    In my examples I used the terms "apparent speed" and "true speed" as nautical terms as they are more readily understood than "proper speed" and "coordinate speed". Of course these apparently conflicting measurements of "movement" can be resolved by scientific measurement and calculations and confirm Relativity.
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    Quote Originally Posted by Write4U View Post
    or is it possible that the muon was formed from other cosmic radiation, an instant before it strikes the earth?
    The muons I was referring to are called "atmospheric muons", and are formed by the interaction between cosmic radiation with the upper atmosphere.

    And lastly, I understand using the muon itself as an observer and as such it would experience the effects of relativity such as time dilation, because (as I understand it) its inherent clock runs slower than inherent clocks of other particles, which I assume is the reason why it decays slower than other particles.
    In the frame of the Earth, the muon reaches the surface because of time dilation, i.e. because it decays at a slower rate as compared to the Earth bound observer. In the frame of the muon itself, the surface is reached because the atmosphere of the Earth is length contracted along the direction of travel, so it has a smaller distance to cross. Both frames agree on the physical outcome, i.e. that it reaches the surface. If we disregard all relativistic effects, all muons would decay just over half the distance through the atmosphere, and never reach the surface.

    This why my statement about "apparent speed" (as observed from the shore) and "true speed" (as observed from the knotmeter on the boat) which IMO, is an example of possible problems with our "observation" of relativity.
    Your choice of frame is completely arbitrary; the boat observer is just as right as the shore observer. Both are right in their own respective frames, and they will agree on physical outcomes ( see muons above ). That is the main point in relativity - you can change the frame of reference without affecting any of the laws of physics, i.e. without affecting the outcome of experiments performed. That is Special Relativity in a nutshell.
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    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post

    This is called "relativity", so, in effect you are denying relativity (after grossly misinterpreting it in the prior paragraph). Speed is a frame-variant quantity.
    Interesting that you would use the term "in effect I am denying relativity", which proves my point of "apparent" and "true". I have never denied relativity anywhere in my posts. Apparently to you I have, but you have no proof I said that anywhere, ever.
    Yes, you are denying relativity, except you do not realize it. Markus is explaining that to you in a slightly different way that I did, pay attention to his post above. The gist is the same with what I just told you.
    Last edited by Howard Roark; October 8th, 2014 at 12:37 AM.
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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by Write4U View Post
    or is it possible that the muon was formed from other cosmic radiation, an instant before it strikes the earth?
    The muons I was referring to are called "atmospheric muons", and are formed by the interaction between cosmic radiation with the upper atmosphere.

    And lastly, I understand using the muon itself as an observer and as such it would experience the effects of relativity such as time dilation, because (as I understand it) its inherent clock runs slower than inherent clocks of other particles, which I assume is the reason why it decays slower than other particles.
    In the frame of the Earth, the muon reaches the surface because of time dilation, i.e. because it decays at a slower rate as compared to the Earth bound observer. In the frame of the muon itself, the surface is reached because the atmosphere of the Earth is length contracted along the direction of travel, so it has a smaller distance to cross. Both frames agree on the physical outcome, i.e. that it reaches the surface. If we disregard all relativistic effects, all muons would decay just over half the distance through the atmosphere, and never reach the surface.

    This why my statement about "apparent speed" (as observed from the shore) and "true speed" (as observed from the knotmeter on the boat) which IMO, is an example of possible problems with our "observation" of relativity.
    Your choice of frame is completely arbitrary; the boat observer is just as right as the shore observer. Both are right in their own respective frames, and they will agree on physical outcomes ( see muons above ). That is the main point in relativity - you can change the frame of reference without affecting any of the laws of physics, i.e. without affecting the outcome of experiments performed. That is Special Relativity in a nutshell.
    I did not want to give the impression that I would give preference to one observer over the other. I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.

    This happens in real life. Allow me an example:
    I am sitting in my car at a red light. I am not paying attention to the traffic lights. Suddenly I have an experience of moving backward, but then I realize that I missed the green light and it is the traffic which is moving forward, not me moving backward. This illusion was caused, not from my frame of reference, but from the frame of reference of the moving traffic. From that frame of reference I am moving backward. Although perfectly relativistic, my experience of moving backward was an relativistic illusion....
    Last edited by Write4U; October 8th, 2014 at 02:13 AM.
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    Quote Originally Posted by Write4U View Post

    I did not want to give the impression that I would give preference to one observer over the other. I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.

    This happens in real life. Allow me an example:
    I am sitting in my car at a red light. I am not paying attention to the traffic lights. Suddenly I have an experience of moving backward, but then I realize that I missed the green light and it is the traffic which is moving forward, not me moving backward. This illusion was caused, not from my frame of reference, but from the frame of reference of the moving traffic. From that frame of reference I am moving backward. Although perfectly relativistic, my experience of moving backward was an relativistic illusion....
    You are still denying relativity, though you are denying denying it. Nothing is a "relativistic illusion", what you are experiencing is the fact that motion (inertial) is relative. In the frame of your car, the background is moving in one direction. In the frame of the background, your car is moving (in the opposite direction). Neither motion is more "real" than the other.
    Now, what is confusing you even further is that accelerated motion is NOT relative, it is absolute. If the car next to you accelerates from the stop (while you are still sitting because you aren't paying attention to the traffic light), this is NOT the same to you accelerating from the stop while the guy next to you wasn't paying attention. In the first case, you feel no acceleration, in the latter one you DO.
    Last edited by Howard Roark; October 8th, 2014 at 09:54 AM.
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    hey Science Noob( no offence intended)
    in answer to your question:
    sped is distance covered per unit time.
    now distance requires at least one point of reference in space with which you can measure the distance being covered
    this point would have to be stationary i.e. at rest.
    ....But..... there no absolute rest right?
    therefore you can only measure the distance with reference to a given object and therefore speed also with reference to that body only
    and thus, you can't have a 'true speed"
    also since we cannot calculate the boundaries of the universe, there is no centre.

    as for your second question-
    According to Einstein's theory of relativity, no matter what the speed of the observer, the speed of light remains constant.(i.e. approx. 3 * 10^8)
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    So all in all after having to go through so many pages the only thing I understood is that everything will be measured relative to c and that light is a funny thing?
    So whatever happens even if, assuming that all statements are true,
    Inside an infinitely long vacuum tube X are two people.
    Person A is situated in a fixed point holding a yellow light flashlight while person B is riding a bicycle at c within a similar tube Y travelling at c within another similar tube Z travelling, also at c, inside tube X and still, person B will be able to see the yellow light beam of A. Correct?
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    Not quite, because it is impossible to accelerate a massive body at c: his mass would increase and it would take an infinite energy to do so. But if you take c/2 instead of c, then it is OK for the cyclist, but not for the second tube, again for the same reason.
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    Quote Originally Posted by Write4U View Post
    I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.
    Yes, relativistic effects are not present in a single, isolated frame of reference; rather, they represent the relationship between two or more frames.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    I did not want to give the impression that I would give preference to one observer over the other. I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.

    This happens in real life. Allow me an example:
    I am sitting in my car at a red light. I am not paying attention to the traffic lights. Suddenly I have an experience of moving backward, but then I realize that I missed the green light and it is the traffic which is moving forward, not me moving backward. This illusion was caused, not from my frame of reference, but from the frame of reference of the moving traffic. From that frame of reference I am moving backward. Although perfectly relativistic, my experience of moving backward was an relativistic illusion....
    You are still denying relativity, though you are denying denying it. Nothing is a "relativistic illusion", what you are experiencing is the fact that motion (inertial) is relative. In the frame of your car, the background is moving in one direction. In the frame of the background, your car is moving (in the opposite direction). Neither motion is more "real" than the other.
    Now, what is confusing you even further is that accelerated motion is NOT relative, it is absolute. If the car next to you accelerates from the stop (while you are still sitting because you aren't paying attention to the traffic light), this is NOT the same to you accelerating from the stop while the guy next to you wasn't paying attention. In the first case, you feel no acceleration, in the latter one you DO.
    From my frame of reference was my car accelerating backward? No it was stopped and not moving at all. I experienced an illusion of accelerating backward, which of course was a relativistic experience, but a false one, as I was not moving at all.
    Now you will of course deny my experience and call me a liar or crazy. I expect nothing less.
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    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    I did not want to give the impression that I would give preference to one observer over the other. I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.

    This happens in real life. Allow me an example:
    I am sitting in my car at a red light. I am not paying attention to the traffic lights. Suddenly I have an experience of moving backward, but then I realize that I missed the green light and it is the traffic which is moving forward, not me moving backward. This illusion was caused, not from my frame of reference, but from the frame of reference of the moving traffic. From that frame of reference I am moving backward. Although perfectly relativistic, my experience of moving backward was an relativistic illusion....
    You are still denying relativity, though you are denying denying it. Nothing is a "relativistic illusion", what you are experiencing is the fact that motion (inertial) is relative. In the frame of your car, the background is moving in one direction. In the frame of the background, your car is moving (in the opposite direction). Neither motion is more "real" than the other.
    Now, what is confusing you even further is that accelerated motion is NOT relative, it is absolute. If the car next to you accelerates from the stop (while you are still sitting because you aren't paying attention to the traffic light), this is NOT the same to you accelerating from the stop while the guy next to you wasn't paying attention. In the first case, you feel no acceleration, in the latter one you DO.
    From my frame of reference was my car accelerating backward? No it was stopped and not moving at all.
    Correct.

    I experienced an illusion of accelerating backward,
    Incorrect, I just explained to you that acceleration is absolute, meaning that you either measure it or you don't, it is not, contrary to your misinterpretations, an "illusion". You have a metaphysical understand of reality, you need to learn a physical one.





    Now you will of course deny my experience and call me a liar or crazy. I expect nothing less.
    No, you are not crazy and you are not a liar, you are just ignorant on the subject matter and stubborn in your misconceptions. Have you considered taking an introductory class in relativity? It would help clear your misconceptions (or you'll get thrown out by the instructor if you continue to cling to them).
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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by Write4U View Post
    I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.
    Yes, relativistic effects are not present in a single, isolated frame of reference; rather, they represent the relationship between two or more frames.
    Thanks Markus, for your patience.

    I completely agree with your statement. My original question was about the ability to "accurately determine" the relative relationship between frames, without the use of measurements from all frames of reference.

    In the example of the boat, there are 3 frames of reference , the moving boat (prop is turning), the flow of the river, the stationary observer on the shore.

    In the scenario I described earlier, I made the boat move against the flow of the river, which gave the appearance of a stationary boat to the shore observer. However, if I drop anchor and turn my motor off, the boat becomes a stationary object without movement. Of course it is still moving relative to the flowing stream, but to the casual shore observer, both scenarios, yield the same result, even as the dynamics between boat and river have changed.
    I realize that in both instances a form of energy is used to counteract the flow of the stream, but I feel there is a difference between both scenarios, which of course can be resolved when the information of all three frames of reference is known.

    In scenario one the combined relative opposing movements of boat and river is 10 knots (5 against 5).
    In scenario two the combined movement of the anchored boat and river is 5 knots. (5 against 0)

    In any case the boat remains stationary, relative to the casual shore observer.
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    Quote Originally Posted by Write4U View Post

    In the scenario I described earlier, I made the boat move against the flow of the river, which gave the appearance of a stationary boat to the shore observer. However, if I drop anchor and turn my motor off, the boat becomes a stationary object without movement. Of course it is still moving relative to the flowing stream, but to the casual shore observer, both scenarios, yield the same result, even as the dynamics between boat and river have changed.
    I realize that in both instances a form of energy is used to counteract the flow of the stream, but I feel there is a difference between both scenarios, which of course can be resolved when the information of all three frames of reference is known.
    From a kinematics point of view, there is no difference between the scenarios, the boat has zero relative speed wrt the shore.
    From a dynamic point of view, the relative rest of the boat wrt the shore is achieved via different forces (prop propulsion against the stream, anchor cable strain against the stream).
    What is your point? You keep moving the goalpoasts as soon as your ideas are proven incorrect. Where are you trying to go? What are you trying to prove?

    In scenario one the combined opposing movements of boat and river is 10 knots (5 against 5).
    In scenario two the combined movement of the anchored boat and river is 5 knots. (5 against 0)
    You are comparing apples and oranges, the boat moves at ZERO speed wrt the shore in BOTH cases. The 10 knots speed is known as closing speed, it is the speed of TWO objects (the boat and the river) "covering" a common length as viewed from a third frame of reference (in our case, the shore). The 5 knots closing speed is obtained when the boat no longer moves wrt the shore (so, it is only the river that is moving "downstream").
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    I did not want to give the impression that I would give preference to one observer over the other. I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.

    This happens in real life. Allow me an example:
    I am sitting in my car at a red light. I am not paying attention to the traffic lights. Suddenly I have an experience of moving backward, but then I realize that I missed the green light and it is the traffic which is moving forward, not me moving backward. This illusion was caused, not from my frame of reference, but from the frame of reference of the moving traffic. From that frame of reference I am moving backward. Although perfectly relativistic, my experience of moving backward was an relativistic illusion....
    You are still denying relativity, though you are denying denying it. Nothing is a "relativistic illusion", what you are experiencing is the fact that motion (inertial) is relative. In the frame of your car, the background is moving in one direction. In the frame of the background, your car is moving (in the opposite direction). Neither motion is more "real" than the other.
    Now, what is confusing you even further is that accelerated motion is NOT relative, it is absolute. If the car next to you accelerates from the stop (while you are still sitting because you aren't paying attention to the traffic light), this is NOT the same to you accelerating from the stop while the guy next to you wasn't paying attention. In the first case, you feel no acceleration, in the latter one you DO.
    From my frame of reference was my car accelerating backward? No it was stopped and not moving at all.
    Correct.

    I experienced an illusion of accelerating backward,
    Incorrect, I just explained to you that acceleration is absolute, meaning that you either measure it or you don't, it is not, contrary to your misinterpretations, an "illusion". You have a metaphysical understand of reality, you need to learn a physical one.

    Now you will of course deny my experience and call me a liar or crazy. I expect nothing less.
    No, you are not crazy and you are not a liar, you are just ignorant on the subject matter and stubborn in your misconceptions. Have you considered taking an introductory class in relativity? It would help clear your misconceptions (or you'll get thrown out by the instructor if you continue to cling to them).
    Which misconceptions? Please identify where my metaphysical understanding is contrary to the physical dynamics. Enlighten me, that should not be too difficult. Please don't patronize me without identifying my errors.
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    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    I did not want to give the impression that I would give preference to one observer over the other. I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.

    This happens in real life. Allow me an example:
    I am sitting in my car at a red light. I am not paying attention to the traffic lights. Suddenly I have an experience of moving backward, but then I realize that I missed the green light and it is the traffic which is moving forward, not me moving backward. This illusion was caused, not from my frame of reference, but from the frame of reference of the moving traffic. From that frame of reference I am moving backward. Although perfectly relativistic, my experience of moving backward was an relativistic illusion....
    You are still denying relativity, though you are denying denying it. Nothing is a "relativistic illusion", what you are experiencing is the fact that motion (inertial) is relative. In the frame of your car, the background is moving in one direction. In the frame of the background, your car is moving (in the opposite direction). Neither motion is more "real" than the other.
    Now, what is confusing you even further is that accelerated motion is NOT relative, it is absolute. If the car next to you accelerates from the stop (while you are still sitting because you aren't paying attention to the traffic light), this is NOT the same to you accelerating from the stop while the guy next to you wasn't paying attention. In the first case, you feel no acceleration, in the latter one you DO.
    From my frame of reference was my car accelerating backward? No it was stopped and not moving at all.
    Correct.

    I experienced an illusion of accelerating backward,
    Incorrect, I just explained to you that acceleration is absolute, meaning that you either measure it or you don't, it is not, contrary to your misinterpretations, an "illusion". You have a metaphysical understand of reality, you need to learn a physical one.

    Now you will of course deny my experience and call me a liar or crazy. I expect nothing less.
    No, you are not crazy and you are not a liar, you are just ignorant on the subject matter and stubborn in your misconceptions. Have you considered taking an introductory class in relativity? It would help clear your misconceptions (or you'll get thrown out by the instructor if you continue to cling to them).
    Which misconceptions? Please identify where my metaphysical understanding is contrary to the physical dynamics. Enlighten me, don't insult me.
    Incorrect, I just explained to you that acceleration is absolute, meaning that you either measure it or you don't, it is not, contrary to your misinterpretations, an "illusion".
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    @Howard Roark,
    From a kinematics point of view, there is no difference between the scenarios, the boat has zero relative speed wrt the shore.
    From a dynamic point of view, the relative rest of the boat wrt the shore is achieved via different forces (prop propulsion against the stream, anchor cable strain against the stream).
    What is your point? You keep moving the goalpoasts as soon as your ideas are proven incorrect. Where are you trying to go? What are you trying to prove?
    The point was that to the CASUAL shore observer there has been no change in relative position, even though the dynamics of the boat relative to the river have changed, unbeknown to the shore observer.
    If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative to both river and shore observer, while in scenario (b) the boat will remain stationary (its anchored), both to the river and the shore observer.

    Lastly, my underlying assertion was that without measurement from all frames of reference, the observer is unable to accurately determine which dynamics are in play (before we close the dam).

    I believe Markus just confimed that in his last post.
    Last edited by Write4U; October 8th, 2014 at 08:05 PM.
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    Quote Originally Posted by Write4U View Post
    @Howard Roark,
    From a kinematics point of view, there is no difference between the scenarios, the boat has zero relative speed wrt the shore.
    From a dynamic point of view, the relative rest of the boat wrt the shore is achieved via different forces (prop propulsion against the stream, anchor cable strain against the stream).
    What is your point? You keep moving the goalpoasts as soon as your ideas are proven incorrect. Where are you trying to go? What are you trying to prove?
    The point was that to the CASUAL shore observer there has been no change in relative position, even though the dynamics of the boat relative to the river have changed, unbeknown to the shore observer.
    If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative to both river and shore observer, while in scenario (b) the boat will remain stationary (its anchored), both to the river and the shore observer.
    You are stating the obvious.

    Lastly, my underlying assertion was that without measurement from all frames of reference, the observer is unable to accurately determine which dynamics are in play (before we close the dam).
    Depends which observer. The one in the boat will definitely be able "which dynamics are at play", contrary to your claim.
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    Just curious - is Angular motion all relative? I'm no physicist, but i do recall a "law" of conservation of angular momentum, which suggests to an uninformed type like myself that the total of all the angular momentum in the universe balances out to that of the universe's origins. Is there a non relative zero angular motion that has no centripetal acceleration, independent of any local reference?
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    Quote Originally Posted by Ken Fabos View Post
    Just curious - is Angular motion all relative?
    No, it is accelerated (think of a carousel) , so it is absolute.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    @Howard Roark,
    From a kinematics point of view, there is no difference between the scenarios, the boat has zero relative speed wrt the shore.
    From a dynamic point of view, the relative rest of the boat wrt the shore is achieved via different forces (prop propulsion against the stream, anchor cable strain against the stream).
    What is your point? You keep moving the goalpoasts as soon as your ideas are proven incorrect. Where are you trying to go? What are you trying to prove?
    The point was that to the CASUAL shore observer there has been no change in relative position, even though the dynamics of the boat relative to the river have changed, unbeknown to the shore observer.
    If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative to both river and shore observer, while in scenario (b) the boat will remain stationary (its anchored), both to the river and the shore observer.
    You are stating the obvious.
    Thank you, we are in agreement then on this issue.

    Lastly, my underlying assertion was that without measurement from all frames of reference, the observer is unable to accurately determine which dynamics are in play (before we close the dam).
    Depends which observer. The one in the boat will definitely be able "which dynamics are at play", contrary to your claim.
    ok, the river is so wide the observer on the boat cannot see the shore. Will the observer on the boat know he is now moving in relation to the shore? Unless he dropped the anchor and knows he is stationary, he has travelled at 5 knots the entire time. OTOH the casual observer (with binoculars) on the shore will know that the boat is moving relative to the shore, but not at what speed and why it is now moving when a moment ago it was stationary.

    As I understand it: All motion is relative, it just may not appear to us as it happens in reality unless we have data from all frames of reference from which we can "calculate" the relative dynamics between the frames of reference.

    Of course, that is where physics comes in.
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    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    @Howard Roark,
    From a kinematics point of view, there is no difference between the scenarios, the boat has zero relative speed wrt the shore.
    From a dynamic point of view, the relative rest of the boat wrt the shore is achieved via different forces (prop propulsion against the stream, anchor cable strain against the stream).
    What is your point? You keep moving the goalpoasts as soon as your ideas are proven incorrect. Where are you trying to go? What are you trying to prove?
    The point was that to the CASUAL shore observer there has been no change in relative position, even though the dynamics of the boat relative to the river have changed, unbeknown to the shore observer.
    If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative to both river and shore observer, while in scenario (b) the boat will remain stationary (its anchored), both to the river and the shore observer.
    You are stating the obvious.
    Thank you, we are in agreement then on this issue.

    Lastly, my underlying assertion was that without measurement from all frames of reference, the observer is unable to accurately determine which dynamics are in play (before we close the dam).
    Depends which observer. The one in the boat will definitely be able "which dynamics are at play", contrary to your claim.
    ok, the river is so wide the observer on the boat cannot see the shore. Will the observer on the boat know he is now moving in relation to the shore? Unless he dropped the anchor and knows he is stationary, he has travelled at 5 knots the entire time. OTOH the casual observer (with binoculars) on the shore will know that the boat is moving relative to the shore, but not at what speed and why it is now moving when a moment ago it was stationary.

    As I understand it: All motion is relative, it just may not appear to us as it happens in reality unless we have data from all frames of reference from which we can "calculate" the relative dynamics between the frames of reference.

    Of course, that is where physics comes in.
    "If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative..."

    For the last time, acceleration is absolute, an observer closed in a box can tell he is being accelerated .
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    @Howard Roark,
    From a kinematics point of view, there is no difference between the scenarios, the boat has zero relative speed wrt the shore.
    From a dynamic point of view, the relative rest of the boat wrt the shore is achieved via different forces (prop propulsion against the stream, anchor cable strain against the stream).
    What is your point? You keep moving the goalpoasts as soon as your ideas are proven incorrect. Where are you trying to go? What are you trying to prove?
    The point was that to the CASUAL shore observer there has been no change in relative position, even though the dynamics of the boat relative to the river have changed, unbeknown to the shore observer.
    If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative to both river and shore observer, while in scenario (b) the boat will remain stationary (its anchored), both to the river and the shore observer.
    You are stating the obvious.
    Thank you, we are in agreement then on this issue.

    Lastly, my underlying assertion was that without measurement from all frames of reference, the observer is unable to accurately determine which dynamics are in play (before we close the dam).
    Depends which observer. The one in the boat will definitely be able "which dynamics are at play", contrary to your claim.
    ok, the river is so wide the observer on the boat cannot see the shore. Will the observer on the boat know he is now moving in relation to the shore? Unless he dropped the anchor and knows he is stationary, he has travelled at 5 knots the entire time. OTOH the casual observer (with binoculars) on the shore will know that the boat is moving relative to the shore, but not at what speed and why it is now moving when a moment ago it was stationary.

    As I understand it: All motion is relative, it just may not appear to us as it happens in reality unless we have data from all frames of reference from which we can "calculate" the relative dynamics between the frames of reference.

    Of course, that is where physics comes in.
    "If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative..."

    For the last time, acceleration is absolute, an observer closed in a box can tell he is being accelerated .
    But from what speed to what speed and in relation to what? Unless you can measure it in relation to another frame of reference it is meaningless, IMO. Perhaps a more knowledgeable person can clarify this.

    Below is quote from a science advisor on another science forum,
    Actually it is not acceleration that is absolute. It is the rate of change of momentum. In SR, dp/dt is invariant and absolute. https://www.physicsforums.com/thread...bsolute.59283/
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    [QUOTE=Write4U;600803]
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    "If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative..."

    For the last time, acceleration is absolute, an observer closed in a box can tell he is being accelerated .
    But from what speed to what speed and in relation to what? Unless you can measure it in relation to another frame of reference it is meaningless, IMO.
    Your above opinion is wrong. I suggest that you take a class.


    Perhaps a more knowledgeable person can clarify this.

    Below is quote from a science advisor on another science forum,
    Actually it is not acceleration that is absolute. It is the rate of change of momentum. In SR, dp/dt is invariant and absolute. https://www.physicsforums.com/thread...bsolute.59283/
    Well, there are multiple mistakes in what that science adviser (Andrew Mason) is saying. Good luck with your learning.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    "If we close the dam and stop the flow of the river, in scenario (a) the boat will accelerate forward to 5 knots relative..."

    For the last time, acceleration is absolute, an observer closed in a box can tell he is being accelerated .
    But from what speed to what speed and in relation to what? Unless you can measure it in relation to another frame of reference it is meaningless, IMO.
    Your above opinion is wrong. I suggest that you take a class.
    In what way is my opinion wrong? That the "man in the box" or the boatdriver experiences acceleration?

    In our scenario the acceleration against the river is always present. When the river slows down, the man in the closed box will accelerate RELATIVE to the force of the river, but will not experience acceleration at all. He has been accelerating at 5 knots all the time, relative to the river. When the flow of the river diminishes, the boat begins to gain momentum, but only against the stream. The driver does not experience acceleration, unless he can see the shore. Perhaps you need to rethink the dynamics of this relativistic scenario more carefully.

    Perhaps a more knowledgeable person can clarify this.

    Below is quote from a science advisor on another science forum,
    Actually it is not acceleration that is absolute. It is the rate of change of momentum. In SR, dp/dt is invariant and absolute. https://www.physicsforums.com/thread...bsolute.59283/
    Well, there are multiple mistakes in what that science adviser (Andrew Mason) is saying. Good luck with your learning.
    Oh, I am learning a lot. Not so much from you though.

    I suggest that you advise Andrew Mason of the errors in his science. Can't have a science advisor give the wrong advise on a physics forum.
    Last edited by Write4U; October 9th, 2014 at 07:53 PM.
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    Quote Originally Posted by Write4U View Post
    When the river slows down, the man in the closed box will accelerate RELATIVE to the force of the river, but will not experience acceleration at all. .
    This is impossible , I am not going to explain to you again that acceleration is frame invariant, you cannot have acceleration wrt one frame and no acceleration wrt another. Bye.

    The driver does not experience acceleration, unless he can see the shore.
    Shakes head. Sighs. Gives up.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post
    When the river slows down, the man in the closed box will accelerate RELATIVE to the force of the river, but will not experience acceleration at all. .
    This is impossible , I am not going to explain to you again that acceleration is frame invariant, you cannot have acceleration wrt one frame and no acceleration wrt another. Bye.

    The driver does not experience acceleration, unless he can see the shore.
    Shakes head. Sighs. Gives up.
    The man in the box (your scenatio) which is anchored and stationary relative to the shore is always going at 5 knots relative to the stream which is flowing @ 5 knots.. Now the man in the box turns on the motor to 5 knots and lifts the anchor. Will he experience acceleration even though the box remains in its stationary position, relative to the shore?
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    Quote Originally Posted by Write4U View Post
    ... He has been accelerating at 5 knots all the time ...
    "5 knots all the time" contradicts "He has been accelerating".
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    In physics one defines
    is the four-vector called "four velocity". It is a four-vector because it transforms under the Lorentz transforms exactly like the "prototype" for four-vectors,
    is the proper time, the time measured by a clock comoving with the observer.
    It can be demonstrated that the derivative wrt proper time of a four-vector is a four-vector. So is a four vector.
    One property of four-vectors is that their norm is frame invariant, so, the norm of is frame invariant.

    Now, it can be shown that

    where is the coordinate 3-acceleration.

    In the frame where we have two things:

    is now the proper acceleration, measured by an observer comoving with the accelerated object
    (by setting u=0 in the expression of the four-vector , A).

    The above means that :



    The very interesting result we were after is that proper acceleration is frame invariant by virtue of having the norm equal to the norm of the four-acceleration. I feel that all this is going to be lost on Write4U, I made this effort for the benefit of the other members of the forum.
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    This will be of interest to some here :-)

    [deleted link]
    Last edited by Cogito Ergo Sum; October 10th, 2014 at 03:02 AM.
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    Quote Originally Posted by pzkpfw View Post
    Quote Originally Posted by Write4U View Post
    ... He has been accelerating at 5 knots all the time ...
    "5 knots all the time" contradicts "He has been accelerating".
    I did consider that, but decided to use the term as "relative acceleration" against the river's flow of 5 knots, even while remaining stationary relative to the shore.
    It may be the wrong term, however I wanted to ilustrate that all "motion is relative" only to another frame of reference.
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    Quote Originally Posted by pzkpfw View Post
    Quote Originally Posted by Write4U View Post
    ... He has been accelerating at 5 knots all the time ...
    "5 knots all the time" contradicts "He has been accelerating".
    :-)
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    Quote Originally Posted by Howard Roark View Post
    In physics one defines
    is the four-vector called "four velocity". It is a four-vector because it transforms under the Lorentz transforms exactly like the "prototype" for four-vectors,
    is the proper time, the time measured by a clock comoving with the observer.
    It can be demonstrated that the derivative wrt proper time of a four-vector is a four-vector. So is a four vector.
    One property of four-vectors is that their norm is frame invariant, so, the norm of is frame invariant.

    Now, it can be shown that

    where is the coordinate 3-acceleration.

    In the frame where we have two things:

    is now the proper acceleration, measured by an observer comoving with the accelerated object
    (by setting u=0 in the expression of the four-vector , A).

    The above means that :



    The very interesting result we were after is that proper acceleration is frame invariant by virtue of having the norm equal to the norm of the four-acceleration. I feel that all this is going to be lost on Write4U, I made this effort for the benefit of the other members of the forum.
    No, it read this with interest, but I do not recall mentioning any clocks or time in my example. I have never disputed the science of relativity. I only proposed that relative actions may not necessarily be what a casual observer experiences.

    If you are sitting at your computer are you at rest or are you in fact moving in accordance with the rotation of the earth and its rotation around the sun and its rotation within the galactic rotation in the universe? But we do experience "acceleration" towards the center of the earth (gravity), which is experienced as weight, even though we remain at the surface of the earth.

    I am not debating the science of relativity. I am proposing that a casual observer may not personally experience relativity "accurately" from his frame of reference. There are so many frames of reference at work, that any accuracy can only be derived at by scientific calculation of data from all frames of reference, not by personal experience.
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    Quote Originally Posted by Write4U View Post

    I am not debating the science of relativity. I am proposing that a casual observer may not personally experience relativity "accurately" from his frame of reference.
    In other words...you are ONLY disputing the accuracy of relativity.


    There are so many frames of reference at work, that any accuracy can only be derived at by calculation, not by personal experience.
    Interesting crankery. Need to give you points for novelty. .
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by pzkpfw View Post
    Quote Originally Posted by Write4U View Post
    ... He has been accelerating at 5 knots all the time ...
    "5 knots all the time" contradicts "He has been accelerating".
    :-)
    IMO, not necessarily so. He could be accelerating relative to another frame of reference, even though he may be moving at a steady speed (or even being stationary) in his own frame of reference.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by Write4U View Post

    I am not debating the science of relativity. I am proposing that a casual observer may not personally experience relativity "accurately" from his frame of reference.
    In other words...you are ONLY disputing the accuracy of relativity.
    From a single frame of reference, yes.
    There are so many frames of reference at work, that any accuracy can only be derived at by calculation, not by personal experience.
    Interesting crankery. Need to give you points for novelty.
    Thank you. Perhaps there is hope for you yet.
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    To the moderator of this thread.

    I realize that my "probing" is not strictly scientific, so I shall bow out from this thread and leave the actual physics to the scientists.
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    Quote Originally Posted by Write4U View Post
    To the moderator of this thread.

    I realize that my "probing" is not strictly scientific, so I shall bow out from this thread and leave the actual physics to the scientists.
    "Not strictly scientific" is an euphemism. Outright crank is more like it.
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    Quote Originally Posted by Write4U View Post
    IMO, not necessarily so. He could be accelerating relative to another frame of reference, even though he may be moving at a steady speed (or even being stationary) in his own frame of reference.
    Just imagine your observer holding a full cup of coffee. If he or she accelerates, they'll spill coffee. If they don't they won't.

    In your boat example earlier, if the transition from being anchored to using the engine to hold position is smooth, they won't spill coffee. Their speed stays constant relative to the shore (0) and constant relative to the water (5 knots).
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    Quote Originally Posted by pzkpfw View Post
    Quote Originally Posted by Write4U View Post
    IMO, not necessarily so. He could be accelerating relative to another frame of reference, even though he may be moving at a steady speed (or even being stationary) in his own frame of reference.
    Just imagine your observer holding a full cup of coffee. If he or she accelerates, they'll spill coffee. If they don't they won't.

    In your boat example earlier, if the transition from being anchored to using the engine to hold position is smooth, they won't spill coffee. Their speed stays constant relative to the shore (0) and constant relative to the water (5 knots).
    ImO, that is not quite correct. There is a change in dynamics of the situation. When we turn on the motor and lift anchor the boat's true speed changes from 0 knots (while anchored) to 5 knots (under propulsion) against the flow of the river, changing the relative speed from 5 knots (anchored against he flow of the river) to a relative 10 knots (boat speed against the flow of the river). Thus the relativistic speed between boat and river changes (accelerates?) from 5 knots 10 knots, while the boat remains stationary to a third frame of reference (shore).

    Question: if an asteroid is accelerating towards the earth, is the earth not accelerating relative to the asteroid, even though we feel no change in momentum? Is that not a fundamental principle of relative motion?
    Last edited by Write4U; October 10th, 2014 at 06:11 PM.
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    Quote Originally Posted by Write4U View Post
    ImO, that is not quite correct. There is a change in dynamics of the situation. When we turn on the motor and lift anchor the boat's true speed changes from 0 knots (anchored) to 5 knots (propulsion) against the flow of the river, changing the relative speed from 5 knots (against he flow of the river) to a relative 10 knots (boat speed against the flow of the river). Thus the relativistic speed between boat and river changes (accelerates?) from 5 knots 10 knots, while the boat remains stationary to other frames of reference.
    Sorry, but that's rubbish (going by the scenario you originally described). That you switch from using the anchor to using the motor makes no difference to your "true speed". Before and after, the boat is moving at 5 knots through the water. That before, you might consider the water as moving at 5 knots past the boat is irrelevant - the boat does not accelerate.

    Imagine an aircraft flying along, with it's pitot tube(s) measuring an airspeed of 50 knots. If it's engines are switched off, yes it will slow down as it starts to glide, but it's pitot tubes will start off still measuring 50 knots - the air speed of the aircraft doesn't instantly become zero.

    Going by your original scenario - what could the boat be doing to measure "true speed" that would show any difference before and after?

    Quote Originally Posted by Write4U View Post
    Question: if an asteroid is accelerating towards the earth, is the earth not accelerating relative to the asteroid, even though we feel no change in momentum? Is that not a fundamental principle of relative motion?
    If an asteroid is heading towards Earth, and Earths gravity is accelerating the asteroid, the asteroids gravity will also be accelerating the Earth. So both are undergoing acceleration - it's just that Earth will be feeling much less (as it has more mass).

    This isn't an issue of relativity, and in any case is a different case than your anchored then not anchored boat.
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    I don't think that Write4U understands the difference between a physical argument and a philosophical argument.
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    Quote Originally Posted by pzkpfw View Post
    Quote Originally Posted by Write4U View Post
    ImO, that is not quite correct. There is a change in dynamics of the situation. When we turn on the motor and lift anchor the boat's true speed changes from 0 knots (anchored) to 5 knots (propulsion) against the flow of the river, changing the relative speed from 5 knots (against he flow of the river) to a relative 10 knots (boat speed against the flow of the river). Thus the relativistic speed between boat and river changes (accelerates?) from 5 knots 10 knots, while the boat remains stationary to other frames of reference.
    Sorry, but that's rubbish (going by the scenario you originally described). That you switch from using the anchor to using the motor makes no difference to your "true speed". Before and after, the boat is moving at 5 knots through the water. That before, you might consider the water as moving at 5 knots past the boat is irrelevant - the boat does not accelerate.
    IMO, that is incorrect . You are mixing "true" speed with "relative speed". When a boat moves at 5 knots against an opposing stream of 5 knots, the relative speed between the two frames of reference is 10 knots. This was earlier discussed in the example of two photons travelling in opposite directions. Each photon's true speed is "c". The relative speed between both is 2c.

    Imagine an aircraft flying along, with it's pitot tube(s) measuring an airspeed of 50 knots. If it's engines are switched off, yes it will slow down as it starts to glide, but it's pitot tubes will start off still measuring 50 knots - the air speed of the aircraft doesn't instantly become zero.
    This was discussed in the example of "apparent speed and true speed" of an airplane. If a plane is travelling at 200 mph against a head wind of 100 mph, the plane's instruments will register 200 mph, while an observer on earth will see the plane travel at 100 mph.

    Going by your original scenario - what could the boat be doing to measure "true speed" that would show any difference before and after?
    The instruments on the boat will register a speed of 5 knots (the boat does not know the speed of the river, only it's own speed while the shore observer observes no motion at all. If the river were to flow @ 6 knots, the boat would still register 5 knots, but the shore observer will see the boat travelling backward @ 1 knot.

    Quote Originally Posted by Write4U View Post
    Question: if an asteroid is accelerating towards the earth, is the earth not accelerating relative to the asteroid, even though we feel no change in momentum? Is that not a fundamental principle of relative motion?
    If an asteroid is heading towards Earth, and Earths gravity is accelerating the asteroid, the asteroids gravity will also be accelerating the Earth. So both are undergoing acceleration - it's just that Earth will be feeling much less (as it has more mass).

    This isn't an issue of relativity, and in any case is a different case than your anchored then not anchored boat.[/QUOTE]
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    Quote Originally Posted by Write4U View Post
    ... You are mixing "true" speed with "relative speed". When a boat moves at 5 knots against an opposing stream of 5 knots, the relative speed between the two frames of reference is 10 knots. ...
    You are mixing up your scenarios.

    Your scenario that I am commenting on is the one where a river is flowing at 5 knots and the boat is anchored, then the anchor is taken up and the engine turned on (and the boat still running against the flow, at 5 knots). The boat before and after is moving 5 knots relative to the water and 0 knots relative to the shore. There is no 10 knots, there is no difference between "true speed" and "relative speed" here.

    When your boat is anchored, and the water flows at 5 knots, the boat is moving at 5 knots through the water, and 0 knots relative to the shore. When that same boat raises its anchor and runs it's engine to maintain 5 knots against the water, it's still just 5 knots through the water and zero knots relative to the shore. Using the engine or the anchor makes no difference. The boat does not accelerate and the captain doesn't spill her coffee.

    If a boat moves at 5 knots through water, in the same direction as that water is flowing, and that water is flowing at 5 knots relative to the shore - then there would be a 10 knot speed (boat relative to the shore). But that isn't the scenario you described.
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    Quote Originally Posted by pzkpfw View Post
    Quote Originally Posted by Write4U View Post
    ... You are mixing "true" speed with "relative speed". When a boat moves at 5 knots against an opposing stream of 5 knots, the relative speed between the two frames of reference is 10 knots. ...
    You are mixing up your scenarios.

    Your scenario that I am commenting on is the one where a river is flowing at 5 knots and the boat is anchored, then the anchor is taken up and the engine turned on (and the boat still running against the flow, at 5 knots). The boat before and after is moving 5 knots relative to the water and 0 knots relative to the shore. There is no 10 knots, there is no difference between "true speed" and "relative speed" here.

    When your boat is anchored, and the water flows at 5 knots, the boat is moving at 5 knots through the water, and 0 knots relative to the shore. When that same boat raises its anchor and runs it's engine to maintain 5 knots against the water, it's still just 5 knots through the water and zero knots relative to the shore. Using the engine or the anchor makes no difference.

    If a boat moves at 5 knots through water, in the same direction as that water is flowing, and that water is flowing at 5 knots relative to the shore - then there would be a 10 knot speed (boat relative to the shore). But that isn't the scenario you described.
    Right, it isn't the scenario I described. But the instruments on the boat would still only register 5 knots (it does not know the speed of the river) even though the shore observer sees the boat move @ 10 knots.
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    So you agree that in your original scenario, there is no acceleration for the boat?
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    Here is a river (~), it moves from left to right, at 5 knots. On that river is a boat (<bbbb) it is anchored (a).

    Code:
         <bbbb
    
    ~~~~~a~~~~~~~~~>
    Here's the same boat, after the anchor was pulled up and the engine (e) turned on . The boat is doing 5 knots up stream (to the left).

    Code:
         <bbbb
    
    ~~~~~~~~~e~~~~~>
    What difference is there for the boat? Can anyone measure 10 knots here? What's the difference between your "true speed" and "relative speed" here?
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    I don't think that Write4U understands the difference between a physical argument and a philosophical argument.
    You've hit the nail on the head. It's why I don't read anything he posts. The guy is not stupid but he is hung up on what makes sense to him rather than what actually happens. In terms of science you cannot educate someone like that, you ignore them or ridicule them but they will not learn...
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    Quote Originally Posted by PhDemon View Post
    I don't think that Write4U understands the difference between a physical argument and a philosophical argument.
    You've hit the nail on the head. It's why I don't read anything he posts. The guy is not stupid but he is hung up on what makes sense to him rather than what actually happens. In terms of science you cannot educate someone like that, you ignore them or ridicule them but they will not learn...
    This thread needs be moved into Trash. The OP is long gone, his questions have been answered and marcbo+Write4U have hijacked the thread. Neither of them can be convinced that their ideas are unphysical, so they will go forever.
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    Quote Originally Posted by PhDemon View Post
    I don't think that Write4U understands the difference between a physical argument and a philosophical argument.
    You've hit the nail on the head. It's why I don't read anything he posts. The guy is not stupid but he is hung up on what makes sense to him rather than what actually happens. In terms of science you cannot educate someone like that, you ignore them or ridicule them but they will not learn...
    Allow me to refer to this post:
    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by Write4U View Post
    I was not arguing relativity itself, just that relativity may not be readily apparent to a "casual" observer from his frame of reference.
    Yes, relativistic effects are not present in a single, isolated frame of reference; rather, they represent the relationship between two or more frames.
    Last edited by Write4U; October 11th, 2014 at 01:18 AM.
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    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by PhDemon View Post
    I don't think that Write4U understands the difference between a physical argument and a philosophical argument.
    You've hit the nail on the head. It's why I don't read anything he posts. The guy is not stupid but he is hung up on what makes sense to him rather than what actually happens. In terms of science you cannot educate someone like that, you ignore them or ridicule them but they will not learn...
    This thread needs be moved into Trash. The OP is long gone, his questions have been answered and marcbo+Write4U have hijacked the thread. Neither of them can be convinced that their ideas are unphysical, so they will go forever.
    I already bowed out, but was asked a direct question, so I answered it. It would have been rude to ignore it.

    Again, I have stated that I am not arguing against Relativity, just that:
    Originally Posted by Howard Roark
    Originally Posted by Write4U
    I am not debating the science of relativity. I am proposing that a casual observer may not personally experience relativity "accurately" from his frame of reference.
    In other words...you are ONLY disputing the accuracy of relativity.
    From a single frame of reference, yes. There are so many frames of reference at work, that any accuracy can only be derived at by calculation, not by personal experience from a casual observation.
    That was the gist of my posts, no more, no less.

    And Howard Roark, why do you not include yourself as hijacker. Were you not also participating in this exchange?
    Last edited by Write4U; October 11th, 2014 at 01:22 AM.
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    Quote Originally Posted by pzkpfw View Post
    Here is a river (~), it moves from left to right, at 5 knots. On that river is a boat (<bbbb) it is anchored (a).

    Code:
         <bbbb
    
    ~~~~~a~~~~~~~~~>
    Here's the same boat, after the anchor was pulled up and the engine (e) turned on . The boat is doing 5 knots up stream (to the left).

    Code:
         <bbbb
    
    ~~~~~~~~~e~~~~~>
    What difference is there for the boat? Can anyone measure 10 knots here? What's the difference between your "true speed" and "relative speed" here?
    I answered that question already, but as my posts seem to interfere with the "physical" discussion of "all motion is relative", I shall not make further posts or answer any further questions.
    Last edited by Write4U; October 11th, 2014 at 01:44 AM.
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    Quote Originally Posted by Write4U View Post
    I answered that question already, ...
    Not clearly. You're all over the place. I'm trying to simplify, to take it one step at a time.
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    Quote Originally Posted by Write4U View Post
    Quote Originally Posted by Howard Roark View Post
    Quote Originally Posted by PhDemon View Post
    I don't think that Write4U understands the difference between a physical argument and a philosophical argument.
    You've hit the nail on the head. It's why I don't read anything he posts. The guy is not stupid but he is hung up on what makes sense to him rather than what actually happens. In terms of science you cannot educate someone like that, you ignore them or ridicule them but they will not learn...
    This thread needs be moved into Trash. The OP is long gone, his questions have been answered and marcbo+Write4U have hijacked the thread. Neither of them can be convinced that their ideas are unphysical, so they will go forever.

    And Howard Roark, why do you not include yourself as hijacker. Were you not also participating in this exchange?
    I am simply bating down the crankery.
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