Hi Omnibus, johanfprins, vergon, RealityCheck, prometheus, fairy, buttershug, NoCleverName, Trout et al,
I am about to post a long answer but considering this single thread has lasted over 24 web pages with a lot of heat and no light... I have decided to "speak up"... I apologize for the length of this post but only because I can tell you what this answer actually is and end this confusion for those who can actually understand the argument and read the references clearly... I also apologize for any typos in advance as there always will be some...
I have not been "intimately" involved with this discussion but it seems to me that it gets way off the track with side issues and this is the result of an "ill defined" problem. With all due respect... what I said in my initial post on this thread on page 1 still stands.
Good Elf on this thread earlier.Einstein's initial paper included "relativistic mass" (though not explicitly stated he used longitudinal and transverse mass... not good!) and that point is implicit in section 10 (the most disputed section). This is not a good idea and Einstein himself stated this later (.. as I quoted in that original post of mine). This is "doubly confirmed" by the quote by Wheeler and Taylor that followed it. We should only use
"invariant mass" (Do not use "rest mass" which implies the idea of "relativistic mass"). This says "nothing" about the Prof. LB Okun... Lev Okun was the head of the Laboratory of Elementary-Particle Theory at the Institute of Theoretical and Experimental Physics, in Moscow, USSR (So... he is no "slouch"). I have found a link to his presentation in Physics Today June 1989.
Lev Okun, The Concept of Mass, Physics Today, June 1989.He is still presenting major papers on this and other subjects at prestigious events and has stood his ground regarding this "principle" calling it a "pedagogical virus".... I tend to agree. So please look into this matter carefully... this link above is pretty clear and provides a lot of philosophical "meat". Because nobody has stated just what this problem is and what various equations are supposed to mean... I will assist and try to provide the answer to just one "simple" problem. Feel free to criticize but keep within the "fenceline" of my problem and please do not confound it with some other undefined problems with "no fencelines"... OK?
Ignore those conventions in the link above and pay the price as you all play games with the various definitions of what is being observed. In my opinion is is a "bad move" to deal with any "relativistic mass", we should only deal with
"invariant mass" on which "everyone" who understands what is going on agrees. I can see that this has not been agreed on and "all hell is released" and unless somebody states that the mass is the "invariant mass" then the equation F = ma will not hold in each and every reference frame. Let me say it for you...
"m" is the invariant mass... the one and only mass... OK!... and you have sometimes been referring to "relativistic mass" which "cannot be agreed upon" as Einstein stated and is no longer a "correct theoretical concept". Forget it! There is "relativistic energy" but that is quite different (see below).
Einstein did nothing wrong from the historical context of his time, though anyone who uses these "old" ideas today needs to be very clear that he/she is no longer at liberty to bend rules since they have already been "set in stone". What you are all doing is trying to create some self-consistent argument with the advantage of hindsight... This is not a "textbook perfect" case and there are inevitable inconsistency and Levy Okun, John A Wheeler, Edwin Floriman Taylor and Albert Einstein (also many others) have warned everyone of the consequences. The Fourmilab commentary on Einstein's Paper should also be heeded and should have also alerted you all to "problems" in the original paper (specifically that section) and nobody should be directly quoting the controversial parts of Einstein's Paper directly...
read the footnotes.... specifically the one related to para 10 where we are speaking of that transverse and longitudinal mass.
Most technical papers have errors in them, but the general truth of Einstein's paper is still there despite some problems. Relativity exists and it is not possible to avoid the consequences of time dilation and length contraction (as some suggest... this is total nonsense)... these are real measurable phenomena and they affect "real clocks" and real "measuring rods", though perhaps not in the way people think because of this "smokescreen" of directionless nonsense created by an inadequate educational system whose desire it is to make everything seem to be "self evident" and through the confusing influence of Okun's "pedagogical virus".
Just to expand and clear up on the "historical process" of Einstein's Special Theory... Over the following years since 1905 a number of matters were "elucidated" and "emphasized" by Einstein. This include the fact that the second "Principle" (... of two basic Special Relativity "Principles") was not required .... the constancy of the speed of light is
already part of Maxwell's Equations and is not specifically required as an
assumption.
see paragraph 2 of "ON THE ELECTRODYNAMICS OF MOVING BODIES" By A. Einstein June 30, 1905Many people do not realize that the earlier Maxwell's Equations are "already unified" as being entirely consistent with the Special Theory of Relativity and they remain so to this day. There are some "wild statements" to the contrary in this Forum (and in other places)... they are entirely wrong. Einstein has not changed anything related to that. Another aspect was the problem with "relativistic mass" and the need to understand and use only
"invariant mass"... that topic we are currently "unfortunately" discussing. Please note... The "meaning of invariant mass" is that "matter" has "rest energy" equal to mc² in addition to any "potential and or kinetic energy" and is measured in the
rest frame of the matter to which it applies. You measure that rest mass "comparatively" using a spring in that freely falling inertial system and measure the relative accelerations applied "equally" to two different masses (one a test mass) that are contra-accelerated using the masses attached to the ends of the spring... m'a' = m"a" where a"/a' = m'/m" (easy peezy!). Note there are no "absolute masses" because we do not know the absolute energy content of any mass, we only know their relative masses (aside from Burkard Heim who had some interesting ideas but I tend to disagree because I think the principle of Relativity "overrides" this "absolute mass" calculation concept). This is because all energy is "relative" to some arbitrary "zero point". We measure "rest mass" in comparison to a
standard mass. There is absolutely no way (till now) of determining the mass of a particle from first principles. Probably it would be a violation of Einstein's Theory right there... and if you prove it you can probably put your hand out for "The Gong".
Every inertial "rest" frame measures the same "invariant mass" and any comparisons "between frames" should be in terms of this "invariant mass" that is measured in any "rest frame" the masses are to be internally consistent. This does not mean that you will not find "difficulties" with many important papers in the field and with references on the Internet where there is "absolute nonsense and even lies". It is the nature of scientific papers to be "presented" in the most turgid way possible to confuse the "unwashed multitudes".
The energy content of a particle is composed of a rest energy mC² plus the kinetic and potential energy. Of course those potential and kinetic energies are also "relative to something somewhere" and depends on how you measure them and with respect to"what"? I try and think of contained "systems" rather than the separate particles.
There were other very minor technical errors in the paper as well and you can read them as commentary at the bottom of the Fourmilab "re-translation".
ON THE ELECTRODYNAMICS OF MOVING BODIES By A. Einstein June 30, 1905 (referenced above)One matter in the para 10 is there as a caution (as I mentioned)... footnote 9. In case people have not read it... it states "explicitly"...
"The definition of force here given is not advantageous, as was first shown by M. Planck. It is more to the point to define force in such a way that the laws of momentum and energy assume the simplest form. Editor's Notes". This does not change the fact that Einstein "is still" correct. Things are done differently nowadays and what you are arguing about is "hindsight". Einstein never even studied Maxwell's Equations at his Institute that he graduated from.... he had to interpret all that from his own personal readings at a time when there was no "Internet"... So unlike all of you who have been versed in these matters with 100 years of thoughtful contemplation, Einstein needed to work things out for himself, and in these matters he may have made some problems with his own definitions. As noted previously ... he was not a good teacher... But he was a good scientist. So much for the history lesson.
The next point to bring up is far more complex, subtle and technical and also more critical to
this discussion. The idea of "relativistic acceleration". This is
not a term related to relativistic mass. What this
really means (and we need to all agree on this) is the observation of remote virtual forces developing in an arbitrary "non-relativistically accelerating" particle moving at very high velocity (with a relative frame speed a significant portion of the speed of light) viewed by a non-accelerating observer in/from an inertial frame of reference. It must also be stated that only one of these two frames can be accelerated if we are to use "simple" Special Relativity and the "actual" accelerated frame is clearly the one in which an acceleration is actually felt... other frames in which we may "see" accelerations are no guarantee that they are truly accelerating because our frame may be the one accelerating relative to that "external" frame (accelerations are vectors and can sum to unusual values relative to various frames). You can easily tell if a frame is being accelerated "for real" if a spring balance
in the frame shows an extension F = mg where g is an acceleration. If there is no "extension" ... there is no "inertial" acceleration. No acceleration does not mean that the mass is undefined... we have discussed that point already above. There might be "practical problems" doing things in general but the principle must be considered first and foremost in any "consistent theory".
For instance falling freely in a gravity field tells us the object "falling freely" is not "currently" suffering the time dilation due to Special Relativity while an object being actually accelerated such as yourselves on the surface of the earth
are being accelerated (have a look at a spring balance and the way it extends) and are therefore the ones undergoing the "time dilation" (I am assuming quite low velocity here). The previous history of a particle is important only if the clock synchronization "in the one frame" occurs prior to an acceleration phase or "boost". Subsequently the time dilation between the frames is "cumulative" depending on the duration the particle remains at a high velocity... that is a property of spacetime.
This also means that clocks in the lower floors of buildings run slower "relative" to clocks in the upper stories of the same building due to it's slightly lowered gravitational acceleration rate being further from the center of the earth.
This can be easily measured and is not something that is able to be simply argued in a "debate"... it is just a "fact". A "remote observation" of the kinematics of a relatively moving frame of reference alone is no guarantee that an "observed acceleration" is due to inertial forces or due to frame dragging so it is not possible to say for sure if the clocks are "actually" running slower in the moving frame relative to a "stay at home clock" that has been accelerated, then brought back together and compared in the same observer frame once more. Only the accelerated clock will be time dilated due to Special Relativistic Motion when compared with a clock that was initially synchronized with in the one frame before the trip (as what might occur on a round trip to some star system at a very high relativistic velocity). The ideal is assumed that the clock left behind will be in free fall in it's own "unaccelerated" observer frame. In the case of an observer left behind on the earth and the twin goes off at one gee acceleration then I would expect to see little or no difference on return since the General Principle of Equivalence states that the inertial and gravitational accelerations are absolutely equivalent.
The "actual" ponderable forces (like the forces acting in gravity) in any accelerating frame of reference can be considered as piecemeal "inertial" and "in frame" and might be in any generalized direction... and for all short "boosts" this internal acceleration is "low" and should be "non-relativistic" though the relative base velocity of the frame can be very high (relative to the observer frame). The "history" of the frame and any relative velocity with respect to some other frame may mean nothing when considering the "small" vector acceleration so the idea that simply taking the second derivative of the
relative position vectors
between frames will provide any measure of the acceleration in the accelerated frame is misleading and avoids the question and also disguises it. After all... this is an "accelerating frame" by definition and while we are speaking about is
Special Relativity then the best way to treat this as Special Relativity is to consider the accelerating frame as being "frozen" at two different sequential points in time (events) in their frame then compared with the "permanently" inertial (unaccelerated) frame of the observer and the transformations "correcting" between frames should indicate that the two snapshots of the "accelerating" frame will be seen "accelerating" relative to the first un-accelerated frame only by a "difference".
Instantaneously each "pseudo-piecewise-inertial frame" is moving with constant (though high) relative velocity (though each snapshot has a different "low" constant velocity changed by an "internal acceleration"). This acceleration is remotely observed and we are trying not to determine the acceleration as it "appears" by just remotely observing this dilated phenomenon but to estimate the effect of what the "test pilot" in a rocket moving with such a particle may "feel" or what he may discover to be the acceleration in that non-inertial frame. The answer is "obviously".... F' = τF (translated... the "force" or the acceleration measured in the observer rest frame (primed) of the
distant accelerated frame must be identical to the observations of the kinematics measured in the accelerated frame via a set of transformations (τ). We need to have synchronized clocks and the origin of the frames need to be set so a single sighting can be made of the accelerating particle in each subsequent "snapshot".
The idea is that the position vectors and times are is not so "obvious" since the propagation times of an observation "signal flash" back to a
single observer must be corrected for propagation times. For instance what does the word "simultaneously" mean to any remotely observed event in an accelerating non-inertial accelerating reference frame moving "through" an inertial observer reference frame like a jet from a distant black hole or rapidly retreating Hubble shifted quasar being frame dragged away from us? Clearly it does not mean "measured at the same time" as it does in Newtonian Physics (... the speed of propagation of light would be infinite) because light takes time to propagate from distant points
in the rest frame of the observer, in and from the distant universe. The observer time of observation needs correction "back" to the time in the rest frame where the event occurred.
t = T - ct'
t = true observer frame time of a properly synchronized remote event.
T = observed "simultaneous time" but "uncorrected" in the observer frame.
ct' = time of propagation "directly" to the observer origin in the observer frame (as a ray length S = ct'... the minus sign indicates that the event occurred "before" it was observed at the origin of this inertial frame).
This T is the time an observer at the origin of the observer rest frame would think is the time after T0 = 0 (time when all clocks in the inertial frame and the clock of the "subsequently" accelerated frame were all set to zero in the one observer rest frame) that is then an event seen at a remote position of the rest frame. The time t is what should be recorded as an estimate of the time in the frame at the remote position of the event at the end of the optical vector S (where the flash is seen in the rest frame). In reality for "cosmic events" the observed position of these events needs "something more" to determine how far away an event is. Currently we use simple optical parallax due to the diameter of the orbit of the earth for nearby targets or Hubble shift to determine distance by measuring the red shift in the spectral bands of the moving source's light. Otherwise we would not have a clue at all, it would all still be a complete mystery (which in all probability it probably still is).
Alternatively assuming that we have a "johnny on the spot" everywhere of interest in the observer frame where interesting events are occurring then the equations everyone knows "apply" if that "Johnny on the spot" carries a synchronized clock and "knows where he is in the rigid
inertial frame xyz coordinate system". This requires the "Einstein clock synchronization convention" that all should be aware of to achieve this "minimum requirement". Otherwise a correction "in-frame" is required. Distant events on the other side of the Universe must be corrected for global spacetime curvature which we "earth observers" really do not entirely understand or normally actually see yet (... check the WMAP Data for instance). There are exceptions where we can actually "see" spacetime curvature for instance where gravitational lensing has occurred in the vacuum of space in "Einstein's Rings". However Special Relativity only applies over a "piecemeal flatspace" and we know spacetime itself is not only curved but even measurably still "stretching".
If we understand this then the acceleration "always" depends on mass through the equation F = ma or F' = ma' (for equivalent masses measured in different frames) and to have any meaning these forces must be convertible and they are absolutely independent of any relative velocity between frames and small accelerations... but most importantly to get these values they must be measured within the relatively moving frame itself and the mass "estimated" must be the
"invariant mass".
QUOTE (Trout+)
You can derive it yourself, provided that you know elementary calculus:
p=mv/sqrt(1-(v/c)^2)
F=dp/dt
Let's see your level of mathematical ability. Did you graduate from high school, tutu-boy?
Trout has mentioned (above) that we should deal with change in momentum... that is correct up to a point but to say that F = ma is not true (see reference below) then state that F=dp/dt makes a mockery of convention... what is the difference since dp/dt = mdv/dt = ma? What else could it mean since there is actually only one mass not two?... but once again errors result when there is no common paradigm. One moment Trout admonishes the relativistic mass and the next moment he is using it?...
QUOTE (Trout Today at 5:54 AM+)
The formula valid for any velocity is F=dp/dt
where p=momentum
In relativity, momentum is given by p=m_0*v/sqrt(1-(v/c)^2)
where m_0=proper mass, v=particle speed, c=speed of light
So, if you know any calculus, you can now go back and calculate the force.
Let's see if you can calculate a simple derivative
.. Here Trout is quoting a "proper mass"... m_0 ... why the extra "m"... m is the "invariant mass" = "proper mass" and he calls it m_0??? Thus he shows p = mv = m_0*v/sqrt(1-(v/c)^2)... two different things meaning one thing? Which is it to be??
QUOTE (Trout Today at 7:31 AM+)
Actually F=ma only for the trivial case v=0. In this case a=0 so F is trivially equal to zero. It is therefore safe to say that F is never equal to ma.
Not so safe... So acceleration in all kinematics is not even close? It "apparently" only applies when V = 0. Clearly if V = 0 then a = 0 and p =0 etc... his trivial case I presume. I entirely disagree. F = ma in all accelerated system "piecemealwise". It does not depend on any history so it actually means instantaneous acceleration of "proper mass". The change in velocity can be vanishingly small or "moderate" up to many gees... just not too extreme like a million gees for instance "instantaneously" and lasting over a very short time. If you let this "time" drag out then you must integrate along a special curve for a possible varying vector acceleration function. I do not want to go there it is too complicated for this discussion.
This would mean with some qualification that this change in momentum or force (... is related to the change in relative velocity between
two snapshot frames... one at the beginning of a short boost and the other indicating the state of the frame after the short boost). Presumably since "p" in the first of Trout's equations is a relativistically altered momentum... this altered value must be what is "seen" in the observer frame happening to a particle in the "high velocity" frame... as V -> C p -> ∞. While in Trout's second equation the F quoted there to be consistent is what is measured in the observer frame (unprimed) from the unaccelerated frame (it must be an accelerated frame now since we have "forces" acting). We know this is correct where there is only a small relative velocity... this is Newtonian Mechanics... that's fine. As V -> C what does this equation F = dp/dt do? F = dp/dt = m dv/dt as V -> C dv/dt -> 0 (it's acceleration drops to zero as observed in the remote frame). Wrong... the acceleration "in frame" may be anything at all and is not specifically dependent on the relative frame velocity or even it's direction.
There is no "hint" of what might be seen in the observer frame. Clearly F = dp/dt in all "Newtonian systems" which means this is the standard momentum "in frame" not in the observer frame unless interframe velocity V -> 0, then it will be "close" (ignoring all de Broglie effects). Trout's equation B is a non-sequitur from equation A. The "in frame" acceleration is still F = ma where "a" is an acceleration determined "in frame" relative only to the first or second snapshot and not to the observation of the relative V from the observer frame. Trout ... never wants to be explicit but if you want to answer a real problem you must be very explicit. Goal posts will be rearranged and balls will be "hidden" in case anyone should take a "free kick". This is the problem I am trying to give an answer to so I stick whith this.
This equation F = dp/dt holds "only" if the mass here is the "intrinsic or invariant mass" or Trout's "proper mass" (measured in the "instantaneous" rest frame... it does not matter much if it is snapshot 1 or snapshot 2 since this is going to be the "instantaneous" acceleration) and "a" (F = ma) and "a' " (F' = ma') are accelerations and forces measured in the accelerated frame and unaccelerated "observer" frame of masses in those frames. Without some primed frame (observer frame) this is a meaningless set of useless and inconsistent equations and would be marked wrong in any examination by anyone who understands the subject matter. What any rest frame observer wants to know is what "a" is in the accelerated frame and not what "a' " is since as V -> C you will not be able to observe "a" directly since "a" is the proper acceleration or
intrinsic acceleration in the relatively moving and accelerating frame. If you disagree then the question is "what else could it mean?"
As V -> C (the "initial" relative velocity between the inertial frame and the accelerated frame) the "acceleration" of "everything" in the accelerated frame observationally -> 0, everything becomes "relatively frozen" on the light cone wall. It is "difficult" to measure the acceleration of a rocket when V -> C especially if we are unsure of how space is "curved" between the observer and the observed due to non-inertial influences. We know "non-inertial influences" dominate the Universe... called Hubble expansion.
What the observer wants to know is if an "astronaut" in a rocket that is "still" undergoing acceleration as it approaches the speed of light and is "still feeling comfortable" and what acceleration "a" he "feels" in his frame is still currently within human limits. While relative V can approach C, since this V is only the
relative velocity it has absolutely no effect on this intrinsic value of "a" in the accelerated frame which can vary instantaneously and may be arbitrarily aligned. An estimate of the instantaneous acceleration is possible only after correction between the frames piecemealwise.... Agreed? The imprecision in this figure is going to increase as V -> C the measurables of time and position are going to become more and more "difficult" according to the orthogonality of these measurables.
Fourier Transforms and UncertaintyWhat it is not possible to say is that you simply take the second differential of the position vector to obtain the acceleration because the velocity V between the observer frame and the accelerated frame is not applicable and are "distorted" subject to length contraction and time dilation as seen from the observer frame. Common sense and Einstein's first Principle tells us that... that the laws of physics are the same in all frames (that is the meaning according to Einstein that is to be preserved in Special Relativity despite the minor problems stated previously). Even assuming a flatspace this second differential of the position vector does not give the correct acceleration unless the acceleration is
in the same direction as the velocity (any "relativistic" distant receding particle) will always tend to appear to travel directly away from the origin of the observers inertial frame given enough time and space. If the "boost" is "nearly" in that direction (like a rocket boost) then the observed accelerations will tend to the value...
a = a' [ 1 - U²/C²]³⁄² .... this is what you are all looking for in the simplest form for the simplest problem possible.
So F = ma = F' = ma' etc... If U ≈0 then a = a' in the limit but this evaluation works at
all low relative velocity (low compared with the speed of light). This has that caution in it so do not generalize this idea beyond its domain of applicability. This "evaluation" got us to the moon and I am sure it will still be good a million years from now regardless of how we want to calculate kinematics. Full details of the derivation are here...
Acceleration in Special RelativityAsk a few questions if you want me to explain the finer details...
I would point to the composition of relativistic velocities as a starting point here...
How Do You Add Velocities in Special Relativity?The rest of the derivation above is "simple" in that given the simplified problem it is the limit taken in regard to some elementary "fractions" and this treatment does not require any special differentiation or integration as suggested by some if we are trying to determine "instantaneous proper intrinsic relativistic acceleration"... a "lot of words" in case there is any doubt as to what this really means.
It is important to realize that this is only where the acceleration is in the same direction as the inter-frame velocity and that velocity is chosen as the X direction. A more general treatment for arbitrary acceleration in an arbitrary direction should be found here...
Relativistic force transformation - Valery P. Dmitriyev 13Jul 2005It is not "simple" but it is "almost" straightforward but more necessarily complicated... Warning: there are some minor typos in this treatment but the overall results are correct.
Some additional "sticky" points... A "method" is required to allow us to compare the two accelerated frame "snapshots" with the observer frame and that is not so easily done using standard relativity using the relative velocity between the two "snapshot" frames where the time between the snapshots is "arbitrarily short" but not zero. Remember that in the remote observer inertial frame a second of time may be quite different to a "second" in the accelerated frame whose relative velocity may be approaching the speed of light (and the internal "proper velocity" is approaching "infinity" while the "proper acceleration" may remain "internally constant" lets say 1 gee). Remember the "subjective experience of time" in both frames is identical and there is no "increase in any mass" as V -> C. What high relativistic speed provides is the ability to cross vast distances of many light years of space in a short period of ship's time at the expense of dilation of the travelers time relative to his "stay at home twin"... though if that twin undergoes the same history of acceleration gravitationally as our traveler experiences purely relativistically, maybe there will be no time difference at all on a round trip at constant magnitude of 1 gee acceleration. The simplistic relativity equation for time dilation assumes no acceleration of the "stay at home" twin and large change in velocity for the accelerated traveler. In that simplified case it is the accelerated/deaccelerated particle that suffers the time dilation (check it out with a spring balance). It is definitely not a symmetrically interchangeable effect.
To complete this problem easily as shown in the references above you need the law of composition of relativistic velocities and then apply
limiting conditions to the arbitrarily "boosted" particle. It is also important to realize that this relationship between the high velocity particle and the low velocity particle or observer frame is not "universal" but is dependent on important interactions between them to realize their full potential (such as the transfer of "energy"). No interaction then there is no energy. One type of interaction is for the space ship scenario to be a "round trip" where the identical twins begin and end the trip in the same inertial reference frame. Other pairs of particles do not include this high - low velocity relationship so it appears quite different ... what is a constant in all "similarly" accelerated frames at very different relative velocities is the same proper relativistic acceleration (... read simple in-frame acceleration) in all frames and it remains that same acceleration independent of any of the individual relative velocity relationships. That is Einstein's Relativity Principle.
While this "base" velocity "distorts" what is being "visually seen" in/from the observer or "traveler" frame this "base" velocity
has absolutely no independent influence on the
forces or the acceleration in the accelerated frame because these forces are independent of any "relative velocity" between any quasi-stationary "snapshot" of an accelerated frame (treated as an piecemeal unaccelerated frame) and the observer frame and it is solely dependent on this "absolute acceleration" which is felt only in the accelerating frame of which we have two "snapshots" some "short time and distance apart" viewed by/from the observer frame as a "pair" of relativistically moving "objects" at different times and positions "corrected" using the SR transformations.
We first determine the positions and times of events in the two relativistic snapshot frames from the corrected measurements from the observer frame. Once we know the relative positions and times of events between these two snapshots in the snapshot frames of reference, and because the difference between the two frames have only a small acceleration we can estimate this instantaneous acceleration (quite accurately) using Newtonian approximation (assuming the first snapshot was in a frame of "instantaneous rest"). That is where you can use the equation F = dp/dt or even F = ma (... the one we and NASA all know and love!).
We need a value for "a" (above) given a value of "a' " determined from measurements in the observer inertial frame... the measured relative in frame acceleration. The relative "speed" between the observing frame and the accelerating frame is not about to alter any factor in this estimate since it is an "in frame boost". This "boost" does not need to have any relationship whatsoever to the prevailing velocity between frames... not even to its direction. It is "hard" to distinguish a small acceleration in an arbitrary direction of a far off extreme relativistically moving object due to the imprecision and also due to the fewer number of executing events being recorded from the relativistic progression of observations. In the extreme case the object moving away just marginally under the speed of light becomes totally unobserved and even "static" as it recedes away from the observer suffering more and more extreme time dilation until a point is reached where almost no events are occurring in the observed phenomenon resulting in an "observational paradox" of observing "nothing happening" in the limiting case. with "nothing happening" there is no significant temporal progress in what is being observed... it is "frozen in time".
If "Special Relativity" alone was the main determinant in the kinematics of distant objects... none of these distant bodies would "appear" to recede faster than C/2. This is very easy to prove as a body travels at near the speed of light traversing one light second in distance in just marginally over one second of observer frame time, the consecutive flashes from this object can only propagate at a speed of C so the arrival frequency of consecutive flashes is one flash per two seconds while the particle "visibly recedes" at an uncorrected speed in the observer frame of C/2. However this is not the "true" velocity of the near luminally moving particle whose velocity is causing it to "streak ahead" in real terms of that perceived position at nearly the full speed of light that would be recorded by an army of "johnny's on the spot" at rest in the observer frame in close proximity and along the outward path of the particle and successive "johnny's on the spot" recording the particles progress with correctly synchronized clocks and comparing "notes" later to obtain that velocity of nearly C.
In fact there is another seeming paradox of many cosmic bodies appearing to recede at nearly C in the far off distance of the Universe (up to 99%C). This is "impossible" if only a single perspective measurement is made on a body subject only to the influence of Special Relativity (or observation of the frequency of spectral lines)... something "else" is going on to provide these velocities and it might be due to more than just "simple" Hubble Shift... and there are many theories of which I am not about to speak this time.
Clearly this force or acceleration does not transform according to normal Special Relativity because it is something felt "entirely" in the accelerating frame, it is not "between frames" in the way the velocity or the time (events) are transformed "between" relatively moving inertial frames. The accelerations are not entirely covariant forms like the the other system measurables. The acceleration is measured entirely in the accelerated frame and is "mg" for any "rocket", for instance, where g is a constant acceleration of the rocket and each and every point in an ideal "rigid" rocket will undergo that same acceleration.
So I think this answers the original question the way Einstein would have liked to have answered it. I am also using hindsight but I am quoting references and I have respected opinion backing this point of view. Okun's cautions were appropriate and through it all Einstein still shapes up according to his "principles". Sorry about the length but I look behind me and it is a monster of 26 pages of disjointed ideas all competing with each other without this unifying context. Little bits and pieces of other peoples opinions are partially OK but nobody bothered to define a problem in full.
Cheers
johanfprins
28th October 2008 - 02:26 PM
Hi Good Elf,
You have not added anything I did not already know or which clashes with anything I have posted here. But thanks for posting it.
bm1957
28th October 2008 - 02:30 PM
QUOTE (johanfprins+Oct 28 2008, 02:55 PM)
1. the clock in the primed system: Relative to the primed system at any time
t(/) one has that x(/)=0 : Relative to the unprimed system its corresponding coordinates must be t and x
No.
The co-ordinates for the primed clock (relative to the unprimed clock) are x(/) and t(/), which must be calculated using the transforms. You are confusing yourself by using x(/) to represent two different things: the primed clock's location in the primed frame (which is false) and the primed clock's location relative to the unprimed clock.
QUOTE
Obviously I have not tried to prove "that the time A sees at A is equal to the time A sees at B". What I have proved is that the time A sees at A is the same as the time that B sees at B. you will now probably say it is trivial: Even if it is why are you not able to follow the proof?
If that is what you havetried to prove, then you have not done it properly and youhave used poor notation. However, it is trivial andis exactly what every scientist knows is true.
What you have concluded is t=t(/) This is confusing because by convention, t(/) (primed t) is used to represent the time at frame B relative to another frame, A.
If you aren't trying to show that t=t', which is what I thought you were saying, then I have no disagreement with your conclusion, but it is trivial. Your manipulation of the transforms is false, but that's moot if you aren't trying to show that t=t'
bm1957
28th October 2008 - 02:33 PM
QUOTE (johanfprins+Oct 28 2008, 03:13 PM)
I have not said that time dilation is not a real effect: It is a "real relativistic effect" in the sense that an observer A concludes that time dilates at the position of an observer B while in actual fact the time on the clock observed by observer B is changing at the same rate as the time on A's clock. Similarly it is a "real relativistic effect" in the sense that an observer B concludes that time dilates at the position of an observer A while in actual fact the time on the clock observed by observer A is changing at the same rate as the time on B's clock.
These perceptions are created by relative movement and must be taken into account when actions within one system can be observed from the other system. However, as Feynman said, if you cannot "look out", each system will be the same: i.e. a clock in system A will tick away at the same rate as in system B. What my derivation proves is that when you have an interaction from A observed from B and the opposite interaction in B observed from A, you get the exact same time rate as will be the case when you cannot "look out". This is exactly as it must be. This is another feather in the cap for Special Relativity!
Omnibus thus have some valid points: Relativistic effects are in effect "illusions" but these "illusions" have real physical effects for the observer who is experiencing them: And in order to model these REAL PHYSICAL effects, the Lorentz transformations have withstood the test of time!
In that case I'm not really sure what your original point was or who you thought you were in disagreement with.
bm1957
28th October 2008 - 02:34 PM
QUOTE (Omnibus+Oct 28 2008, 03:14 PM)
Have you heard of rhetorical questions?
Like I said, you are confused. Primed quantities are always referring to the primed system. Take some time to learn these things before posting.
Bleurgh...
Omnibus
28th October 2008 - 02:37 PM
QUOTE (bm1957+Oct 28 2008, 09:17 AM)
You are answering no to all questions?
In that case, I think you are beyond help, I give up.
Read my answer carefully. Also, read and try to understand what Einstein has in mind--I gave you two citations to ruminate over. With your questions you're trying to parse something that cannot be parsed.
bm1957
28th October 2008 - 02:40 PM
QUOTE (johanfprins+Oct 28 2008, 03:19 PM)
I cannot remember that I did this: As outlined above the coordinates of the primed clock is x(/)=0 ant t(/) relative to the primed coordinate system while it is x and t relative to the unprimed system, The Lorentz transformations then connect these coordinates.
Similarly the coordinates of the unprimed clock is x=0 and t relative to the unprimed system and x(/) and t(/) relative to the primed system.
You didn't do that.
What I showed is what x(/) should have represented for the equation to be valid. You let x(/)=0, which is not what is required for the equation to be valid. That is where you blundered.
bm1957
28th October 2008 - 02:44 PM
QUOTE (Omnibus+Oct 28 2008, 03:37 PM)
Read my answer carefully. Also, read and try to understand what Einstein has in mind--I gave you two citations to ruminate over. With your questions you're trying to parse something that cannot be parsed.
I asked you three direct yes/no questions.
Are you saying that you were being flippant when you said no, no, no?
Please just answer the first two honestly. If you answer correctly, I can explain your misunderstanding. If you answer incorrectly I can try to explain why you are incorrect. If you disagree at any point then we can discuss it.
Why do you have a problem with that?
Omnibus
28th October 2008 - 02:48 PM
QUOTE
In that case I'm not really sure what your original point was or who you thought you were in disagreement with.
johanfprins is trying to say that although Lorentz transformations don’t give the real truth about spatial and temporal dimensions from within the moving system when observed by the stationary observer, they can be used by the stationary observer for practical purposes as engineering empirical equations. He thinks Lorentz equations somehow help the stationary observer to figure out from his own perspective for his own purposes what the story is from within the moving system.
Thus, although the moving observer sees things proper in his own frame, the deformed image provided by the Lorentz transformations can be of some use, johanfprins thinks, for the stationary observer who actually knows the image is deformed but he (the stationary observer) can always obtain the correct image by undoing them by applying the inverse Lorentz transformations.
This begs the question, why use equations to get a deformed image and then undo them to get the correct final answer?
Good Elf
28th October 2008 - 02:49 PM
Hi johanfprins et al,
QUOTE (johanfprins+)
Hi Good Elf,
You have not added anything I did not already know or which clashes with anything I have posted here. But thanks for posting it.
If people agree with me I am very pleased. We would then be on the same track. I am not looking for "trouble" and if this assists anyone at all I am gratified and pleased to have done it. 27 pages of "stuff" is too deeply "mixed up and turgid" for my taste and even though my reply is "long" it is not nearly as long as what is currently in progress here...
Thanks again... and Cheers
Trout
28th October 2008 - 02:56 PM
QUOTE (GoodElf+)
Trout has mentioned (above) that we should deal with change in momentum... that is correct up to a point but to say that F = ma is not true (see reference below) then state that F=dp/dt makes a mockery of convention... what is the difference since dp/dt = mdv/dt = ma? What else could it mean since there is actually only one mass not two?... but once again errors result when there is no common paradigm. One moment Trout admonishes the relativistic mass and the next moment he is using it?...
If you don't know physics, just say so.
You can't write dp/dt = mdv/dt because "m" is
not a constant, it is
variable by virtue of the fact that m=m(v)=m_0/sqrt(1-(v/c)^2) and "v" is also variable : v=v(t).
It is time for you to stop
pretending.. Hit the books Little Elf.
Omnibus
28th October 2008 - 02:56 PM
QUOTE
Why do you have a problem with that?
You have a problem, not I. Your questions contain ambiguities such as “local obser” and “non-local observer”. There is no such a thing. These questions are senseless and you have to do some reading and thinking in order to understand what really is going on here.
Just a little help. Forget local and non-local and imagine you are in K and know a certain law of Physics in K. Both first postulate and Lorentz transformations give how another observe, an observer at rest with k will view the law you’re seeing in K. Obviously, the observer in k cannot see one and the same law in two different ways.
Does that help?
bm1957
28th October 2008 - 02:56 PM
QUOTE (Omnibus+Oct 28 2008, 03:48 PM)
johanfprins is trying to say that although Lorentz transformations don’t give the real truth about spatial and temporal dimensions from within the moving system when observed by the stationary observer, they can be used by the stationary observer for practical purposes as engineering empirical equations. He thinks Lorentz equations somehow help the stationary observer to figure out from his own perspective for his own purposes what the story is from within the moving system.
Thus, although the moving observer sees things proper in his own frame, the deformed image provided by the Lorentz transformations can be of some use, johanfprins thinks, for the stationary observer who actually knows the image is deformed but he (the stationary observer) can always obtain the correct image by undoing them by applying the inverse Lorentz transformations.
This begs the question, why use equations to get a deformed image and then undo them to get the correct final answer?
I just gave you an accidental pos! Lucky you
Do you know what 'begs the question' means? I think not.
QUOTE
You have a problem, not I. Your questions contain ambiguities such as “local obser” and “non-local observer”. There is no such a thing. These questions are senseless and you have to do some reading and thinking in order to understand what really is going on here.
You're trying to bring down relativity and you admit that you don't know what local and non-local mean?
*Holds head in hands, head drops and hits the desk repeatedly*
Trout
28th October 2008 - 03:04 PM
QUOTE (bm1957+Oct 28 2008, 02:56 PM)
I just gave you an accidental pos! Lucky you
Baaad
Omnibus
28th October 2008 - 03:07 PM
QUOTE
If you don't know physics, just say so.
You can't write dp/dt = mdv/dt because "m" is not a constant, it is variable by virtue of the fact that m=m(v)=m_0/sqrt(1-(v/c)^2) and "v" is also variable : v=v(t).
It is time for you to stop pretending.. Hit the books Little Elf.
You need more than hitting the book, ginger Trout. You need to think. Because Physics books are not the Bible where you can get away on pure faith.
Theory of relativity cannot prove that m is variable. Therefore, the formula m=m(v)=m_0/sqrt(1-(v/c)^2) you’re using is illegitimate. You can slap any formula you wish, as you’ve done, but that doesn’t mean it’s valid.
The above formula is not valid because it contradicts the first postulate of the theory of relativity which requires that the mass m in a given system to be the same mass in all other systems. According to your formula m in one system is in another system m(v) =/= m for v =/= 0. That’s a fatal conflict with the first postulate.
Well, it’s another story if you start insisting that the first postulate isn’t valid. That’ll be very interesting. Go ahead, say it.
bm1957
28th October 2008 - 03:09 PM
QUOTE (Omnibus+Oct 28 2008, 03:56 PM)
Just a little help. Forget local and non-local and imagine you are in K and know a certain law of Physics in K. Both first postulate and Lorentz transformations give how another observe, an observer at rest with k will view the law you’re seeing in K. Obviously, the observer in k cannot see one and the same law in two different ways.
Does that help?
This is your mistake.
The first postulate says that the observer in k will see that same law in k as you are seeing in K.
The transforms tell you how you will see the law in k and how the observer in k will see the law in K.
Does that help?
Omnibus
28th October 2008 - 03:11 PM
QUOTE
You're trying to bring down relativity and you admit that you don't know what local and non-local mean?
Like I said, forget about "local" and "non-local". They are confusing you. We're not discussing quantum mechanics here. Read very carefully what I told you, especially the last post which I hope will really help you understand what's really going on here.
bm1957
28th October 2008 - 03:14 PM
QUOTE (Omnibus+Oct 28 2008, 04:11 PM)
Like I said, forget about "local" and "non-local". They are confusing you. We're not discussing quantum mechanics here. Read very carefully what I told you, especially the last post which I hope will really help you understand what's really going on here.
Read my reply above, it explains your gross misconception.
johanfprins
28th October 2008 - 03:15 PM
QUOTE (bm1957+Oct 28 2008, 04:40 PM)
What I showed is what x(/)
should have represented for the equation to be valid. You let x(/)=0, which is not what is required for the equation to be valid. That is where you blundered.
I did not blunder anywhere:
First epoch: Coordinates of clock stationary in unprimed system:
Relative to unprimed system: x=0, t
Relative to primed system: x(/), t(/)
Coordinates x(/) t(/) calculated by Lorentz transformation from x=0, t: i.e. transforming correctly from unprimed to primed system
Second epoch: Coordinates of clock stationary in primed system:
Relative to primed system: x(/)=0, t(/)
Relative to unprimed system: x, t
Coordinates x, t calculated by Lorentz transformation from x(/)=0, t(/): i.e. ftransforming correctly rom primed to unprimed system
So where did I let x(/)=0 in such a a manner that the transformations are wrong?
You are becoming like Omnibus: Just repeating the same wrong conclusion!
Omnibus
28th October 2008 - 03:16 PM
QUOTE
The first postulate says that the observer in k will see that same law in k as you are seeing in K.
The transforms tell you how you will see the law in k and how the observer in k will see the law in K.
You need the help not I. So don’t ask me “does that help”.
The above only shows your muddled thinking and unwillingness to understand things. I gave you two quotes from Einstein for rumination but you still refuse to understand that both first postulate and the Lorentz transformations, both of them are ways to transform a law from one frame into another. Both of them must give the same result. Read the quotes from Einstein i gave you and don’t fantasize.
Omnibus
28th October 2008 - 03:20 PM
QUOTE
So where did I let x(/)=0 in such a a manner that the transformations are wrong?
This isn't your blunder. The transformations you present are correct. bm1957 is confused, he doesn't know what he's talking about as all his recent post prove.
Your blunder is that you accept x = x(/).
This is untenable because x is in K while x(/) is in k.
In order for x to be equal to x(/) the time t must be equal ti t(/) which is exactly what you were supposed to prove.
johanfprins
28th October 2008 - 03:23 PM
QUOTE (bm1957+Oct 28 2008, 05:09 PM)
The first postulate says that the observer in k will see that same law in k as you are seeing in K.
The transforms tell you how you will see the law in k and how the observer in k will see the law in K.
You are finally getting there:
Your first sentence: That is why the clocks are ticking away at the same rate (as I have derived above)
Your second sentence: This is why a "stationary" observer will experience a time-dilation for a clock moving relative to him/her, although there is not an actual time-dilation within the moving reference frame.
Omnibus
28th October 2008 - 03:29 PM
QUOTE
Your first sentence: That is why the clocks are ticking away at the same rate (as I have derived above)
Your second sentence: This is why a "stationary" observer will experience a time-dilation for a clock moving relative to him/her, although there is not an actual time-dilation within the moving reference frame.
Yes, that's indeed your understanding but that's not what Einstein has in mind.
Recall from §6
"Evidently the two systems of equations found for system k must express exactly the same thing, since both systems of equations are equivalent to the Maxwell-Hertz equations for system K. "
or, say from §3
"We now have to prove that any ray of light, measured in the moving system, is propagated with the velocity c, if, as we have assumed, this is the case in the stationary system; for we have not as yet furnished the proof that the principle of the constancy of the velocity of light is compatible with the principle of relativity."
More importantly, try to understand your blunder when claiming that x = x(/). That unfounded acceptance kills your argument which otherwise is based on correct application of the Lorentz transformations.
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