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On the Lighter Side => New Theories => Topic started by: mad aetherist on 08/01/2019 04:44:50

Title: Einstein's thort-Xs up to 1920?
Post by: mad aetherist on 08/01/2019 04:44:50
Relativity: The Special and General Theory (1920) – Albert Einstein (1879-1955)
https://www.ibiblio.org/ebooks/Einstein/Einstein_Relativity.pdf      https://www.marxists.org/reference/archive/einstein/works/1910s/relative/relativity.pdf
The above 1920 translation by Robert W Lawson  has lots of imaginings, & every imagining is in effect a soft thort-X at least.   But the following  31 are hard core thort-Xs for sure………….

(1)   Ch2. Alby erects a pole perpendicularly on Trafalgar Square to reach a cloud, measuring its L with a rod, to specify position.

(2)   Ch3.  A moving railway carriage with a window, Alby drops a stone to the ground (embankment) & sees the stone descend in a straight line, a pedestrian observes the misdeed from the footpath notices that the stone falls to earth in a parabolic curve.  …. there is no such thing as an independently existing trajectory, but only a trajectory relative to a particular body of reference.

(3) ((2) again)  But with 2 clocks that tick, a man at the railway-carriage window is holding one, a man on the footpath the other -- to better measure the stones falling trajectory.   However we have not taken account of the inaccuracy involved by the finiteness of the velocity of propagation of light.

(4) Ch5.   Railway carriage, embankment, flying raven, 2 observers -- to show movement in a straight line in different frames of reference.

(5)   Embankment, railway carriage, organ-pipe (emitting a note when parallel)(& when perpendicular) -- showing effect of orientation.

(6)   Earth (orbiting the sun), railway carriage (with v = 30 km/sec) -- to show that the laws of nature are not affected by orientation.

(7) Ch6.   Railway carriage, rails, man (walking along carriage)(or standing still for 1 sec), embankment -- theorem of addition of vel (later to be shown false).

(8 ) Ch7.  Embankment, air (removed), ray of light (like man walking), tip of ray (vel c), railway carriage (vel v), railway lines -- vel of ray relative to carriage is less than c.

(9) ((8 ) again). Advising that (8 ) conflicts with the principle of relativity set forth earlier.

(10) Ch8.    Lightning, striking rails on embankment at A & B (far apart) simultaneously, Alby (commissioned to determine whether the 2 events took place simultaneously), meteorologist  (with a theory for simultaneous lighting) -- requires a definition of simultaneity which includes a method to decide.

(11) ((10) again).  Observer (at midpoint M of A-B), holding 2 mirrors (inclined at 90dg to see A&B) -- can see if simultaneous.
Alby says that (11) is ok if the lightning flash vel A-M is the same as B-M. Alby says....
"That my definition satisfies this demand is indisputable. That light requires the same time to traverse the path A-M as for the path B-M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which i can make of my own freewill in order to arrive at a definition of simultaneity". (Comment -- i don't understand this).

(12)   Clocks (placed at ABC of the railway line)(with pointers set simultaneously the same) -- give the time of an event if at an event.
Alby says that (12)  is ok if clocks go at the same rate, ie if they are of identical construction, & at rest in that reference frame. Alby says....
"This stipulation contains a further physical hypothesis, the validity of which will hardly be doubted without empirical evidence to the contrary".

(13)   Ch9.  The Relativity of Simultaneity.   Railway embankment, a very long train (at least 100 carriages)(vel = v), people in the train, 2 strokes of lightning at A & B.  Observer M midway tween A & B on the embankment & observer M' (sitting at M' on the train) coinciding with M at the time of the 2 flashes occur.  Einstein says......
  Events which are simultaneous with reference to the embankment are not simultaneous with respect to the train, and vice versa (relativity of simultaneity). Every reference-body (co-ordinate system) has its own particular time; unless we are told the reference-body to which the statement of time refers, there is no meaning in a statement of the time of an event.

(14) Alby says that (7) was wrong timewise, & says........
Now before the advent of the theory of relativity it had always tacitly been assumed in physics that the statement of time had an absolute significance, i.e. that it is independent of the state of motion of the body of reference. But we have just seen that this assumption is incompatible with the most natural definition of simultaneity; if we discard this assumption, then the conflict between the law of the propagation of light in vacuo and the principle of relativity (developed in Section VII) disappears.

  We were led to that conflict by the considerations of Section VI, which are now no longer tenable. In that section we concluded that the man in the carriage, who traverses the distance w per second relative to the carriage, traverses the same distance also with respect to the embankment in each second of time. But, according to the foregoing considerations, the time required by a particular occurrence with respect to the carriage must not be considered equal to the duration of the same occurrence as judged from the embankment (as reference-body). Hence it cannot be contended that the man in walking travels the distance w relative to the railway line in a time which is equal to one second as judged from the embankment.
  Moreover, the considerations of Section VI are based on yet a second assumption, which, in the light of a strict consideration, appears to be arbitrary, although it was always tacitly made even before the introduction of the theory of relativity.


(15)  Ch10.    Alby says that (7) was wrong distance wise. Instead of a man walking inside a carriage, a point moving -- giving an equation for addition of vel in one direction.  Alby says..........
LET us consider two particular points on the train  1 travelling along the embankment with the velocity v, and inquire as to their distance apart. We already know that it is necessary to have a body of reference for the measurement of a distance, with respect to which body the distance can be measured up. It is the simplest plan to use the train itself as the reference-body (co-ordinate system). An observer in the train measures the interval by marking off his measuring-rod in a straight line (e.g. along the floor of the carriage) as many times as is necessary to take him from the one marked point to the other. Then the number which tells us how often the rod has to be laid down is the required distance.
  It is a different matter when the distance has to be judged from the railway line. Here the following method suggests itself. If we call A' and B' the two points on the train whose distance apart is required, then both of these points are moving with the velocity v along the embankment. In the first place we require to determine the points A and B of the embankment which are just being passed by the two points A' and B' at a particular time t—judged from the embankment. These points A and B of the embankment can be determined by applying the definition of time given in Section VIII. The distance between these points A and B is then measured by repeated application of the measuring-rod along the embankment.
  A priori it is by no means certain that this last measurement will supply us with the same result as the first. Thus the length of the train as measured from the embankment may be different from that obtained by measuring in the train itself. This circumstance leads us to a second objection which must be raised against the apparently obvious consideration of Section VI. Namely, if the man in the carriage covers the distance w in a unit of time—measured from the train,—then this distance—as measured from the embankment—is not necessarily also equal to w.
Note 1.  e.g. the middle of the first and of the hundredth carriage.


(16)  Ch11.   A 3D consideration, by means of a framework of rods, for 3 co-ordinate planes -- showing equations for the Lorentz transforms.

(17) Ch12.  Alby looks at the behavior of a rod in motion, & says.........
  A priori it is quite clear that we must be able to learn something about the physical behaviour of measuring-rods and clocks from the equations of transformation, for the magnitudes x, y, z, t, are nothing more nor less than the results of measurements obtainable by means of measuring-rods and clocks. If we had based our considerations on the Galilei transformation we should not have obtained a contraction of the rod as a consequence of its motion.

(18)  Alby looks at the behavior of a rod in motion, & says.........
  Let us now consider a seconds-clock which is permanently situated at the origin (x' = 0) of K'. t' = 0 and t' = 1 are two successive ticks of this clock. The first and fourth equations of the Lorentz transformation give for these two ticks:
t = 0 and  [equation not shown] As judged from K, the clock is moving with the velocity v; as judged from this reference-body, the time which elapses between two strokes of the clock is not one second, but [equation not shown]  seconds, i.e. a somewhat larger time. As a consequence of its motion the clock goes more slowly than when at rest. Here also the velocity c plays the part of an unattainable limiting velocity.
 

(19) Ch13.  The Fizeau experiment, the vel of light in a moving liquid in a tube. The tube plays the part of the railway embankment, the liquid the carriage, the light plays the part of the man walking -- Zeeman's measurements accord with the above equation to within 1%.  (Alby ignores Fresnel's priority).

(20)  Ch18.  Embankment, railway carriage -- either are ok for a reference-body re the general laws of nature.

(21)   An occupant, brakes (giving a jerk & non-uniform motion) -- Galilean law does not hold (& mentions general principle of relativity).

(22) Ch20. A spacious chest (in space), with hook & rope attached to middle of lid, with a "being" pulling, observer (man)(with legs) inside chest (equipped with apparatus), observer fastened with strings to floor, viewed from another reference-body which is not being pulled with a rope, he releases a body which he previously had in his hand – the acceleration of the body towards the floor of the chest is always of the same magnitude, whatever kind of body he may happen to use for the experiment -- leading to law of equivalence of inertial & gravitational mass.

(23)   The man in the chest fixes a rope to the inner side of the lid & attaches a body to the free end of the rope.  The rope stretches & hangs "vertically" downwards.  The man in the chest & an observer poised freely in space will have different interpretations – leading to law of equivalence of inertial & gravitational mass.

(24)  Re observer in carriage experiencing a jerk due to brake -- might interpret this to be a gravitational field.

(25)  Ch21.   Alby, a gas range, with 2 pans (alike, half filled with water), steam emitting from only one pan, a luminous blueish color under this pan but not the other -- Alby is not astonished by the different behaviour.

(26)  Ch22.  A ray of light in the accelerated chest -- the path is curvilinear -- we conclude that in general rays of light are propagated curvilinearly in gravitational fields. The law of the constancy of the velocity of light in vacuo cannot claim any unlimited validity, & curvature can only take place when the velocity of propagation of light varies with position, in which case the special theory of relativity holds only if we are able to disregard the influences of gravitational fields on light.

(27)  Ch23.  A plane circular disc rotating in its plane, an observer on the disc might think he was at rest & that the force was gravitational -- an outside observer would interpret it as an effect of inertia & centrifugal force.

(28)  Observer on disc uses clocks & rods.  A clock at the rim is in motion & ticks  slower than a (stationary) clock at the center (for both observers), even though the observer on the disc thinks both clocks are at rest.  Alby says that this shows that in a gravitational field a clock will tick more quickly or less quickly according to position.

(29).  If the observer on the disc uses a short rod to measure the circumference & diameter, he will arrive at a ratio larger than pi, because the rod is contracted when measuring the circumference of the rotating disc, but not when measuring the dia.  Alby says that this shows that Euclidean geometry cannot hold exactly on the rotating disc, nor in general in a gravitational field.

(30)  Ch25.  Alby, a marble table (or slab), wholly covered by a large number of little rods arranged in squares giving Cartesian co-ordinates & a Euclidean continuum, & using one little testing-rod for squareness.  We heat the central part of the slab, those rods expanding & giving disorder.   Cartesian co-ordinates must then be discarded, & replaced by another which does not assume the validity of Euclidean geometry for rigid bodies, corresponding to the situation in general relativity.

(31) Re (30)    "…… Gauss undertook the task of treating this two-dimensional geometry from first principles, without making use of the fact that the surface belongs to a Euclidean continuum of three dimensions.  If we imagine constructions to be made with rigid rods in the surface (similar to that above with the marble slab), we should find that different laws hold for these from those resulting on the basis of Euclidean plane geometry, the surface is not a Euclidean continuum with respect to the rods, & we cannot define Cartesian co-ordinates in the surface.  Gauss indicated the principles according to which we can treat the geometrical relationships in the surface, and thus pointed out the way to the method of Riemann of treating multi-dimensional, non-Euclidean continua.  Thus it is that mathematicians long ago solved the formal problems to which we are led by the general postulate of relativity…..".
Title: Re: Einstein's thort-Xs up to 1920?
Post by: guest4091 on 10/01/2019 18:41:10
Quote
(11) ((10) again).  Observer (at midpoint M of A-B), holding 2 mirrors (inclined at 90dg to see A&B) -- can see if simultaneous.
Alby says that (11) is ok if the lightning flash vel A-M is the same as B-M. Alby says....
"That my definition satisfies this demand is indisputable. That light requires the same time to traverse the path A-M as for the path B-M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which i can make of my own freewill in order to arrive at a definition of simultaneity". (Comment -- i don't understand this)
.
The equivalence of the 'inertial frame' to a 'pseudo rest frame' requires the outbound transit time to equal the inbound transit time. Since an absolute velocity for the frame (c-v or c+v) cannot be detected,it must be defined.
Title: Re: Einstein's thort-Xs up to 1920?
Post by: mad aetherist on 10/01/2019 22:08:36
Quote
(11) ((10) again).  Observer (at midpoint M of A-B), holding 2 mirrors (inclined at 90dg to see A&B) -- can see if simultaneous.
Alby says that (11) is ok if the lightning flash vel A-M is the same as B-M. Alby says....
"That my definition satisfies this demand is indisputable. That light requires the same time to traverse the path A-M as for the path B-M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which i can make of my own freewill in order to arrive at a definition of simultaneity". (Comment -- i don't understand this.)
The equivalence of the 'inertial frame' to a 'pseudo rest frame' requires the outbound transit time to equal the inbound transit time. Since an absolute velocity for the frame (c-v or c+v) cannot be detected,it must be defined.
I dont remember why i said that i dont understand (i wrote that a couple of years ago).  Alby makes that stipulation re the equalness of the time taken (which of course also means the equalness of the speed of light) to give a definition of simultaneity in his system. But how can Alby say that in reality it is neither a supposition nor a hypothesis about the physical nature of light?  Physics is all about reality.  Is it an admission that his thort-X has nothing to do with reality? 
The aetherian objection is that the speed of light always depends on direction, because (for one thing) we always have an aetherwind (here blowing throo the rails & embankment & carriage etc).

Alby then introduces 3 clocks to better nail down that the flashes do travel both ways at the same speed. Here the three events are timed to prove that the two strokes were simultaneous (actually it only needs 2 clocks to prove this)(the 3rd clock is superfluous).  The aetherist objection here is that in reality if the 2 strokes are simultaneous then the flashes cannot be seen as being simultaneous (using the 2 mirrors), because as i said light speed always varies with direction.  Altho u dont have to be Einstein to point out that if the 2 flashes happened to travel square to the aetherwind then in that unlikely case yes by symmetry the speed of the 2 flashes would be equal in both directions (but each would be perceived or timed to be less than c kmps)(c kmps being the SOL in aether). 

In the end what it boils down to is that if Alby makes certain assumptions then (if using good logic) he quite rightly arrives at certain results. But none of that means that thems assumptions suppositions hypotheses stipulations & postulates are true, & if not true then the resulting principles & laws etc are unlikely to be real (or if real then that would only be due to happenstance)(which science calls equivalence).