Shannon’s View on Wheeler’s credo by Eckard Blumschein

Eckard

Unfortunately, I do not understand the phrase: "However, different perspectives must not be taken at a time", so I am not sure what your objection is to what I am saying. Perpectives/calibrations/mearurements/whatever, are all irrelevant in the sense that reality occurred, and it was a definitive, discrete, physically existent state of whatever comprises it, ie there is only one at a time. So the first postulate, even with the superfluous caveat, is a statement of the obvious. A law is a generic valid representation of reality. And reality occurs independently, and the physical circumstance thereof is not affected by observation, etc. Then whilst any 'co-ordinate' can be utilised as the reference, the resulting calibration is not reality, but a calibration thereof. Establishing reality involves the comparison of a range of such calibrations.

So the essential point with postulate one is that physical existence is not affected by which co-ordinate/reference is utilised to calibrate it (forget the superfluous caveat about motion). Postulate two is about the constancy of light. How then to reconcile the two postulates, because we know there is a timing difference? This is why in introducing the second postulate he writes that it is "only apparently irreconcilable" with the first.

His reconciliation is SR, which, as defined by Einstein, involves:

-only motion that is uniform rectilinear and non-rotary

-only fixed shape bodies

-only light which travels in straight lines at a constant speed

It is special because there is no gravitational force (or more precisely, no differential in the gravitational forces incurred).

Nothing is happening in this circumstance, so the two postulates will reconcile. He then moves on to GR. But the point is he did not deploy the second postulate as defined, there was no observation. Another point is that in 1905, light is in vacuo, whilst everything else is not, so the two cannot physically co-exist. In SR (as defined by him) everything is in vacuo, and then in GR, everything is not.

Re simultaneity:

Simultaneity: Lorentz and Poincaré

18 The misconception of time and timing, which is effectively the formalisation of the ontologically incorrect way in which reality is perceived generally, arose through the flawed conceptualisation of simultaneity.

19 Following Voigt and Doppler, Lorentz starts to use the concept of local time:

Lorentz, 1895, section 3:

"The form of this expression suggests to introduce a new independent variable instead of t...the variable t' can be regarded as a time, counting from an instant that depends on the location of the point. We can therefore call this variable the local time of this point, in contrast to the general time t. The transition from one time to another is provided by equation (34)...In a point that moves together with the luminous molecule-and thus also for an observer who shares the translation... We can also examine, with which frequency these values in a stationary point are changing their sign. This frequency causes the oscillation period for a stationary observer...The "observed" period of oscillation is thus...is in agreement with the known law of Doppler. If the law, as it is usually applied, should be given, it must of course still be assumed, that the translation does not change the actual period of oscillation of the luminous particles. I must abstain from giving an account of this hypothesis, since we know nothing about nature of the molecular forces that determine the oscillation period. The case that the light source is at rest and the observer progresses, allows of a similar treatment...We most conveniently describe the perception of motion by means of a co-ordinate system, which shares the translation ...of the observer... from which it is given for the "observed" period of oscillation..."

Lorentz, 1895, section 5:

"We want to call the two states of motion-in the stationary and in the moving system of bodies...corresponding states. Now, they shall be mutually compared more precisely.

a. If in a stationary system the magnitudes (69) are periodic functions of t with the period T, then in the other system the magnitudes (70) have the same period with respect to t', thus also with respect to t, when we let x, y, z remain constant. When interpreting this result, we have to consider, that two periods must be distinguished in the case of translation (see paras 37 and 38), which we accordingly can call absolute and relative period. We are dealing with the absolute one, when we consider the temporal variations in a point that has a fixed position against the aether; but we are dealing with the relative one, when we consider a point that moves together with ponderable matter. The things found above can now be expressed as follows: If a state of oscillation in the moving system shall correspond to a state in the stationary system, then the relative oscillation period in the first mentioned case must be equal to the oscillation period in the second mentioned case.

b. In the stationary system, no motion of light may take place at an arbitrary location... so that at this place the motion of light is missing as well."

20 Comment: although the analysis overtly states an incorrect presumption, ie that there is a local time (ie instant at a specific spatial location), which is different from a common time (ie some form of general time), in practice, and without commenting on the quantifications attributed to the various effects and the precise detail, the underlying concepts are correct. That is, following on from Voigt and Doppler, timing is being related to oscillation/frequency, ie sequence over time. Existence, and the receipt of an observable representation of that, are being differentiated; even the fact that any hypothesised effect on matter will include the same effect on an observer is noted. The overall conclusion being that the actual rates of change (frequency) will remain the same, ie perception does not affect reality, and that the perceived rate of change will not vary if there is no variance in spatial position. Lorentz acknowledges a lack of precise understanding of how the physical process involved happens.

21 Later, Lorentz continues:

Lorentz, 1899, para 6:

"We shall now show how our general equations may be applied to optical phenomena. For this purpose we consider a system of ponderable bodies, the ions in which are capable of vibrating about determinate positions of equilibrium. If the system be traversed by waves of light, there will be oscillations of the ions, accompanied by electric vibrations in the aether. For convenience of treatment we shall suppose that, in the absence of lightwaves, there is no motion at all; this amounts to ignoring all molecular motion... an extremely small quantity, because the diameter of the ions is a very small fraction of the wave-length. This is the reason why we may omit the last term...if the displacements are infinitely small, the same will be true of the velocities and, in general, of all quantities which do not exist as long as the system is at rest and are entirely produced by the motion...We may therefore omit the last terms...In the system without a translation...would be, in all points of an ion, the same functions of t', i. e. of the universal time, whereas, in the moving system, these components would not depend in the same way on t' in different parts of the ion, just because they must everywhere be the same functions of t. However, we may ignore this difference, of the ions are so small, that we may assign to each of them a single local time, applicable to all its parts...we must add the equations of motion for the ions themselves. In establishing these, we have to take into account, not only the electric forces, but also all other forces acting on the ions. We shall call these latter the molecular forces and we shall begin by supposing them to be sensible only at such small distances, that two particles of matter, acting on each other, may be said to have the same local time."

Lorentz, 1899, para 8:

"In what precedes, the molecular forces have been supposed to be confined to excessively small distances. If two particles of matter were to act upon each other at such a distance that the difference of their local times might not be neglected, the theorem would no longer be true in the case of molecular forces that are not altered at all by the translation. However, one soon perceives that the theorem would again hold good, if these forces were changed by the translation in a definite way, in such a way namely that the action between two quantities of matter were determined, not by the simultaneous values of their coordinates, but by their values at equal local times.

If therefore, we should meet with phenomena, in which the difference of the local times for mutually acting particles might have a sensible influence, and in which yet observation showed the above theorem to be true, this would indicate a modification, like the one we have just specified, of the molecular forces by the influence of a translation. Of course, such a modification would only be possible, if the molecular forces were not direct actions at a distance, but were propagated by the aether in a similar way as the electromagnetic actions."

22 Comment: pursuing his hypothesis about the effect of movement on molecular forces, Lorentz suggests how several effects which are either neglible in themselves, or at least when the system is at rest, can be discounted. Again, the point is not so much about whether the detail of this argument is correct, but that it generated, and gave substantiation to, the concept that 'local time' differences could be ignored when considering certain distances (ie "excessively small distances"). As a simplification, this is correct. But unless it is understood to be a simplification, and what has been simplified is known, then its inadvertent reification subsequently can lead to significant errors. That is, in physical existence, by definition, there is always a spatial difference, which means there is always a time delay whilst that light travels. Consciously ignoring this when it has minimal effect for practical reasons, is not the same as asserting that it does not exist.

23 The thoughts of Poincaré on the subject of time and timing, expressed concurrently with those of Lorentz above, are as follows:

Poincaré, 1898, para 1:

"So long as we do not go outside the domain of consciousness, the notion of time is relatively clear. Not only do we distinguish without difficulty present sensation from the remembrance of past sensations or the anticipation of future sensations, but we know perfectly well what we mean when we say that of two conscious phenomena which we remember, one was anterior to the other; or that, of two foreseen conscious phenomena, one will be anterior to the other. When we say that two conscious facts are simultaneous, we mean that they profoundly interpenetrate, so that analysis can not separate them without mutilating them."

Poincaré, 1898, para 2:

"Think of two consciousnesses, which are like two worlds impenetrable one to the other. By what right do we strive to put them into the same mold, to measure them by the same standard? Is it not as if one strove to measure length with a gram or weight with a meter? And besides, why do we speak of measuring? We know perhaps that some fact is anterior to some other, but not by how much it is anterior. Therefore two difficulties: (1) Can we transform psychologic time, which is qualitative, into a quantitative time? (2) Can we reduce to one and the same measure facts which transpire in different worlds?"

Poincaré, 1898, para 3:

"The first difficulty has long been noticed; it has been the subject of long discussions and one may say the question is settled. We have not a direct intuition of the equality of two intervals of time...When I say, from noon to one the same time passes as from two to three, what meaning has this affirmation?... To measure time they use the pendulum and they suppose by definition that all the beats of this pendulum are of equal duration. But this is only a first approximation; the temperature, the resistance of the air, the barometric pressure, make the pace of the pendulum vary."

Poincaré, 1898, para 4:

"All this is unimportant, one will say; doubtless our instruments of measurement are imperfect, but it suffices that we can conceive a perfect instrument. This ideal can not be reached, but it is enough to have conceived it and so to have put rigor into the definition of the unit of time. The trouble is that there is no rigor in the definition. When we use the pendulum to measure time, what postulate do we implicitly admit? It is that the duration of two identical phenomena is the same; or, if you prefer, that the same causes take the same time to produce the same effects."

Poincaré, 1898, para 13:

"To conclude: We have not a direct intuition of simultaneity, nor of the equality of two durations. If we think we have this intuition, this is an illusion. We replace it by the aid of certain rules which we apply almost always without taking count of them.

But what is the nature of these rules? No general rule, no rigorous rule; a multitude of little rules applicable to each particular case. These rules are not imposed upon us and we might amuse ourselves in inventing others; but they could not be cast aside without greatly complicating the enunciation of the laws of physics, mechanics and astronomy. We therefore choose these rules, not because they are true, but because they are the most convenient, and we may recapitulate them as follows: "The simultaneity of two events, or the order of their succession, the equality of two durations, are to be so defined that the enunciation of the natural laws may be as simple as possible. In other words, all these rules, all these definitions are only the fruit of an unconscious opportunism."

24 Comment: this simplistic analysis of time and timing is fundamentally flawed. But it was this thinking that lead to the incorrect definition of simultaneity, and the consequent attribution of a local time to everything. Timing devices only 'tell' the time, ie they are not the time. That is, as far as is practicable, they are a representation of the actual reference, which is a constant rate of change. Duration is as measurable, and subject to the same practical issues in doing so, as any other quantity, contrary to his assertion. Poincaré concentrated on time in the sense of, at the same time, because he failed to understand the true nature of the reference, what timing devices represent, and that timing over a duration actually involves comparing numbers of changes, irrespective of type, in order to calibrate rates of change. Neither is consciousness or intuition relevant, this only applying to a subjective evaluation of time and the relative timing of occurrences, which is not a physical issue.

25 Later, Poincaré continues:

Poincaré, 1900, page 20:

"It is the case that, in reality, that which we call the principle of relativity of motion has been verified only imperfectly, as shown by the theory of Lorentz. This is due to the compensation of multiple effects, but:...2. For the compensation to work, we must relate the phenomena not to the true time t, but to a certain local time t' defined in the following fashion.

Let us suppose that there are some observers placed at various points, and they

synchronize their clocks using light signals. They attempt to adjust the measured

transmission time of the signals, but they are not aware of their common motion, and

consequently believe that the signals travel equally fast in both directions. They perform observations of crossing signals, one travelling from A to B, followed by another travelling from B to A. The local time t' is the time indicated by the clocks which are so adjusted. If V = 1/√Ko is the speed of light, and v is the speed of the Earth which we suppose is parallel to the x axis, and in the positive direction, then we have: t' = t − v x/V2."

Poincaré, 1900, page 22:

"Suppose T is the duration of the emission: what will the real length be in space of the perturbation?...The real length of the perturbation is L = (V - v')T. Now, what is the apparent length?...the local time corresponding to that is T(1-vv'/V2). At local time t', it is at point x, where x is given by the equations: t ' = t − vx/V2,

x = v'T + V(t - T), from which, neglecting V2: x = [v'T + V(t - T)](1 + v/V)...The apparent length of the perturbation will be, therefore,

L' = Vt' - (x - vt') = (V - v')T(1 +v/V) = L(1 + v/V)."

26 Comment: although the Michelson experiments had a null result, the concept of light travelling at different speeds with respect to earth, depending on their relative movement, is still maintained. As two moving entities, this must be so. Leaving aside actual variations in real conditions, the calibrated speed of light is dependent on a reference. In this circumstance, since the earth also has been attributed with a movement, then the reference is 'space'. Which is deemed, by virtue of being the reference, to be 'stationary'. Deeming an entity as the reference means it is, conceptually, stationary. That is the essence of measuring, ie identifying difference by comparison with a constant reference.

27 The notion of dimension alteration, which was hypothesised by Lorentz and Fitzgerald as an explanation for that null result, manifests here in the context of perturbation. This also may be correct. But the key point is that all the variables are now identified, and when taken out of context/applied incorrectly, this results in the fundamental mistake, which involves reifying time by presuming that there is duration, as in elapsed time, in distance. The example also involves the other fundamental mistake of conflating observational light with light used for the purpose of timing. The light beam is a timing mechanism ("they synchronize their clocks using light signals"), and is therefore a constant, its actuality as light is irrelevant. Light is being used to drive a timing device, ie as opposed to (say) crystal oscillation. Whereas observational light is the moving physical entity which enables sight, and does therefore vary in actual speed, depending on environmental conditions encountered, but more importantly, calibrated speed depending on the reference.

28 Following on from this, Poincaré develops the notion that 'everything is relative':

Poincaré, 1902, para 77:

"Hence, our law of relativity may be enunciated as follows: The readings that we can make with our instruments at any given moment will depend only on the readings that we were able to make on the same instruments at the initial moment. Now such an enunciation is independent of all interpretation by experiments. If the law is true in the Euclidean interpretation, it will be also true in the non-Euclidean interpretation."

Poincaré, 1902, para 90:

"...that treatises on mechanics do not clearly distinguish between what is experiment, what is mathematical reasoning, what is convention, and what is hypothesis....

1. There is no absolute space, and we only conceive of relative motion; and yet in most cases mechanical facts are enunciated as if there is an absolute space to which they can be referred.

2. There is no absolute time. When we say that two periods are equal, the statement has no meaning, and can only acquire a meaning by a convention.

3. Not only have we no direct intuition of the equality of two periods, but we have not even direct intuition of the simultaneity of two events occurring in two different places.

4. Finally, is not our Euclidean geometry in itself only a kind of convention of language? Mechanical facts might be enunciated with reference to a non-Euclidean space which would be less convenient but quite as legitimate as our ordinary space; the enunciation would become more complicated, but it still would be possible.

Thus, absolute space, absolute time, and even geometry are not conditions which are imposed on mechanics."

29 Comment: this analysis represents the culmination of what has gone before, and is incorrect. Legitimate concepts have been taken out of context and misinterpreted, in order to infer a physical existence that has no independent existent definitiveness. It is then asserted that this improved conceptualisation highlights the flaw with the previous (classical) stance. Whereas in fact, Poincaré failed to understand the functionality of measuring systems, the devices utilised to effect calibration, and the actual references underpinning those systems. All of which lead to the erroneous conclusion that 'everything is relative', ie there are no absolutes. This erroneous analysis encapsulates the essence of relativity.

30 Finally:

Poincaré, 1904, page 6:

"The most ingenious idea is that of local time. Let us imagine two observers, who

wish to regulate their watches by means of optical signals; they exchange signals,

but as they know that the transmission of light is not instantaneous, they are careful

to cross them. When station B sees the signal from station A, its timepiece should

not mark the same hour as that of station A at the moment the signal was sent,

but this hour increased by a constant representing the time of transmission. Let

us suppose, for example, that station A sends it signal at the moment when its

time-piece marks the hour zero, and that station B receives it when its time-piece

marks the hour t. The watches will be set, if the time t is the time of transmission,

and in order to verify it, station B in turn sends a signal at the instant when its

time-piece is at zero; station A must then see it when its time-piece is at t. Then

the watches are regulated."

"And, indeed, they mark the same hour at the same physical instant, but under

one condition, namely, that the two stations are stationary. Otherwise, the time

of transmission will not be the same in the two directions, since the station A, for

example, goes to meet the disturbance emanating from B, whereas station B sees

before the disturbance emanating from A. Watches regulated in this way, therefore,

will not mark the true time; they will mark what might be called the local time,

so that one will gain on the other. It matters little, since we have no means of

perceiving it. All the phenomena which take place at A, for example, will be

behind time, but all just the same amount, and the observer will not notice it since

his watch is also behind time; thus, in accordance with the principle of relativity

he will have no means of ascertaining whether he is at rest or in absolute motion."

31 Comment: this is correct, until the caveat: "but under one condition, namely, that the two stations are stationary". By definition, synchronised watches are synchronised, they do not cease to be so because of movement. Neither do they, unless they are malfunctioning, depict any other time than the "true time", within the realms of practicality, which is not the point being made anyway. The practical difficulty of ensuring all timing devices are synchronised is an issue which needs to be resolved, otherwise timing devices are useless.

32 The explanation of the caveat is revealed by the phrase: "Otherwise, the time of transmission will not be the same in the two directions". That is, the statement really is being made in the context of light reality, and observational light has been conflated with the mechanism used for timing. The allusion to relative movement resulting in some physical effect is therefore spurious. So, in that context, the statement is correct. But not for the reasons implied. The difference between entities involved in a constant spatial relationship, and being in one that is altering, in the context of receiving light, was explained in para 15 above. That is, the rate of change of a sequence will appear to alter if the time delay for the receipt of light is altering.

33 Obviously, movement, ie alteration in spatial relationship, whilst observational light is travelling, will result in different timings for the receipt of an observable image of an event (ie "goes to meet the disturbance"). And assuming all other factors to be equal/neutral, this will be a function of distance. But, when he writes of: "the time of transmission", the reference is to the light signal being used as a timing mechanism, which is different, and by definition, a constant. So relative movement is being attributed with some effect which is non existent, it being, in the context of observation, an optical illusion. Neither is the identification of movement relative to any given reference dependent on timing. So while the logical point is correct, ie that it is impossible to discern what is 'actually' moving and what is not, that is irrelevant, since the reference for calibrating relative movement is spatial position, not timing.

Paul

Eckard

There are no paradoxes if you understand what Einstein actually did, as opposed to what he said he was doing, and everybody (including himself believed he was doing).

The answer to your question is:

-because people do not read what was written. I am just lucky because I am able to read all the players involved on the net, and have no baggage

-because people do not understand how reality must occur, ie one physically existent state at a time

-because of egos, money, jobs, etc

-because I am a nobody, so whilst at best people will engage in the first place, once they get stuck, they then give up thinking that he must be wrong but cannot spot it, as the professors and everybody else obviously knows best.

I will look at these references.

Paul

Eckard

I am not sure I understand you, because obviously one can have as many 'perpectives' (or better phrasing is calibrations with respect to a reference) as are possible. It makes no difference to the reality, ie the physically existent state of whatever comprised it at that time, being calibrated. There is no such thing as 'birds eye or divine'. We are within a closed system, therefore the only way to discern what that constitutes is from within it, and involves comparing 'perspectives', and on the basis of understanding how they were established, extrapolating what occurred (within the confines of the closed system). The rule is to ensure comparability of references, ie converting all to a common denominator.

Paul

Eckard

"Is there a naturally privileged location/perspective in space?"

No. By definition, any judgement is made with respect to some specific reference, and assuming it has been effected properly it is correct wrt that reference. But that is not necessarily reality.

"Is there a natural point of reference?"

Yes, reality, ie what actually occurred. But one needs to correlate specific judgements and reconcile their individual references to find out what that was.

Obviously timing is common, that is the whole point of it. That is why timing devices are, within the realms of practicality, synchronised. In other words, all functioning wrt the same reference (ie a conceptual constant rate of change). 10.25 GMT is in effect meaningless, it is just a point on the scale. In just the same way that whatever point in time is chosen (which in order to isolate a reality would have to be far more definitive) is in effect zero. Which is the same as when one designates an entity as the reference for momentum, and is therefore, in effect, deeming it to be 'at rest'. It is reality which is determining all this, because it occurs in one physically existent state at a time, which means there is a turnover rate of realities as the sequence progresses.

Paul

Eckard

The synchronisation method that Einstein used does not work because it is the wrong conception of how timing works, and it was meant to apply to the receipt of a light based representation of reality, which would have been correct, but it did not, because there was no observation in Einstein as there was nothing to observe with. So the differential in effect was deemed a characteristic of reality itself. Einstein thought it would not be so when there was relative motion because they thought that what causes this motion also causes length alteration.

Leaving aside the nuance of the first postulate which you have, for me anyway, highlighted by quoting the original words, the whole spirit of it is that reality, and hence any law depicting it, do not alter depending on the reference used to calibrate it (forget the superfluous 'no relative motion' caveat). Which is obviously true, it is the calibration which alters as a function of what is used as the reference to effect the calibration.

It has nothing to do with timing devices. They just tell the time as best thy can. Physical existence is a sequence of realities, each one being a discrete, definitive, physically existent state of whatever comprises it. Time is the rate at which that sequence alters.

I have not read that paper yet, as I now set off to renovate my son's flat, and most evenings just fall asleep on return.

Paul

Dear Eckard,

My sincere apologies. I see I've been missing out on a very interesting discussion. Before I read through it and try to join back in, I want to refer back to your post on Jul. 7, 2013 @ 06:43 GMT. Since I've fallen out of sequence there, I'm posting this in a new thread.

The only thing that bothers me in what you wrote is the statement that you "consider it fallacious to have different perspectives at a time".

I think you're thinking too much about these people making observations and not enough about what their natural definition of space and time should be. I think we can get to the former easily enough after we deal with the latter--so I just want to ask you: do you think it's unreasonable for Albert to string out a measuring tape along the track and plot a graph of what he perceives as occurring along that axis of "space" through the course of "time"? Or to add a vertical tape measure and make a two-dimensional graph of an object's path through the two spatial dimensions? Or make a full three-dimensional graph?

Do you think it's any less reasonable for Henri to string out measuring tape along the floor and the wall of the train car and do something similar?

The principle of relativity says that they should both be able to do this, and the laws of physics should apply just as well in both of their frames.

Now, the clocks that they have with them in the first phase of the experiment have the same vertical distance between the mirrors, and a single photon bounces up and down. When this happens, the clock displays the number of "ticks", sending photons in all directions (and in these guys' frames of reference they can correct for the amount of time it takes those photons to reach their eyes by travelling through "space", etc.), so the experiment can actually be carried out in theory. But that really doesn't need to happen if you already just accept that their two coordinate systems are reasonable to use, because then you already know what's going to happen, from either perspective.

From Albert's perspective, H's clock moves to the right. The path of the photon in the clock on the train is therefore not vertical, but moves at an angle to the right. By the Pythagorean theorem, it travels a longer distance than the photon in Albert's clock, which just went up or down. Assuming c is a universal constant, this means that the "tick" of Henri's clock, as described by Albert, takes longer (t=d/c) than the "tick" of Albert's clock, as described by Albert.

The paradox is that the whole experiment can be *described* from Henri's perspective, where he just sits at rest and Albert moves gradually along his ruler. From Henri's perspective, the photon in his own clock goes vertically up and down, and it's Albert's that travels to the right. For all the same reasons as before, we conclude that as described in Henri's frame of reference, Albert's clock ticks more slowly than Henri's.

You said before that you "question the necessity to ascribe a different proper time to the observer" (meaning Albert in this example). This is the reason why. Relativistic time dilation is a real effect in the real world, and it's not a trivial problem to reconcile the fact with the ticking of an absolute clock. You also said that to you, "only the motion of the observer re train, or vice versa, is relevant", and not whether the train is actually moving. This was Einstein's way of thinking, and it's why I said before that you were thinking as a pure relativist. And the issue--the reason you and I are not seeing eye to eye, as far as I can tell--is that without defining a true cosmic frame of reference, actual or absolute motion, etc., and considering only relative motion as what matters, it's logically inconsistent to say that there is one absolute time, three-dimensional space is all that exists, time passes and all of reality is the three-dimensional present that exists "now", etc.

Time-dilation has to be admitted from a relativistic perspective, and it has to be reconciled with a global reference frame in order for it all to work. The way of actually allowing that their proper times tick at different rates while admitting an absolute time and the *existence* of a three-dimensional universe, is to define simultaneity as absolute, and therefore as something different from synchronicity. You and Paul are right that Einstein got simultaneity wrong, by defining it from an operationalist point of view. This is the point I keep trying to make. And I keep trying to show exactly how relativity works--and it works beautifully!--when it's understood in this way.

Cheers,

Daryl

Paul,

You said you find it stunning that anyone ever read past section 1 part 1. The reason is that everything was headed towards positivism. It was a load of positivists who got us to where we are today.

Regarding your answers to Eckard's question, I don't disagree with them, except for the last one. I've now written two essays arguing for the same presentist position as you, and against Einstein's "simultaneity=synchronicity", and trying to explain in detail just how relativity should be more objectively interpreted, and you simply object to everything. I think the closest you've ever come to agreeing with me was above, where you said you thought I'd agree with something you had written, but then proceeded to state your belief that there has to be a difference in our views.

Please let me state once more exactly where Einstein went wrong on the whole simultaneity/synchronicity issue:

A and B stand a distance d apart and B signals A. It takes t=d/c from the time of emission to the time of observation.

Now A is jogging towards B and B signals A when A is precisely d away. It takes t

Dear Eckard and Paul,

I have some comments. First of all, reading through this discussion has confirmed for me that I was right (see below) about the point of "at the same time" being a point of confusion in this discussion. Eckard, when one says that one reference frame or another can be used to describe events, the meaning is not that one person can be in two places at the same time. The meaning is that any frame of reference is suitable to describe the same sequences of events. And the theory *does* provide a consistent way to transform from the coordinates of one frame to another.

A simple exercise will help you to see this graphically. Draw a vertical line and a horizontal line and call them t and x, respectively. Now draw the lines t=x and t=-x. Now draw another line passing through the origin, rotated 30 degrees to the right of the t-axis. Call that t'. If t=x and t=-x represent the paths of photons through x in t, which both recede from an observer who sits at x=0 with unit velocity, and if the line t' is the worldline of another observer who moves through x in t, then clearly the photon that moves along t=x isn't moving away from this observer as quickly as the one that moves along t=-x.

But motion and speed are all relative anyway, and we want to be able to say that the photons both recede with unit velocity from the perspective of this other observer as well. Something tells me you think this can't be described consistently on this same graph--i.e., that a consistent description can't be given at the same time from either perspective. Am I right about this? Again, my sincere apologies if I'm mistaken about this point of confusion.

Anyway, it can. Draw a line rotated 30 degrees above the x-axis and call it x'. Now draw a line parallel to x' that lies somewhere above it. You should now have seven lines on the page, so it's getting a bit messy, but we're done drawing lines. Now, on the last line you drew, I want you to draw a dot where it intersects the two photon world-lines as well as where it intersects t'. These three events are synchronous along this observer's proper axis of space at this particular value of t'. And the distance that the two photons travelled from t'=0 to this value of t' should be the same in either direction along x'. If you drew the graph with a ruler, you can measure it.

Therefore, "at the same time" the same sequences of events can be described from both perspectives, and indeed, from either observer's perspective the speed of light is the same in both directions.

The only extra bit, in bringing things up to speed with Minkowski's 1908 paper, is that in order for the speed to have the same magnitude in both coordinate systems, this has to be a hyperbolic transformation, which rescales the axes relative to one another. Graphically, that's all there is to the Lorentz transformations in SR.

And indeed, you should plainly see that the synchronous events in one coordinate frame are not synchronous in the other. But both frames do provide accurate descriptions of the same sequence of events.

Now, you've asked if there is a naturally "privileged" perspective. If there's to be absolute simultaneity--i.e. if Einstein got it wrong when he defined synchronous events as simultaneous, and there's only a 3D Universe Now--then there has to be an absolute reference frame, relative to which bodies are either actually in motion or not; and when they actually are in motion, the actually simultaneous events will not be described by them as synchronous.

Daryl

Sorry, I forgot that the less than symbol doesn't work here:

Now A is jogging towards B and B signals A when A is precisely d away. It takes t less than d/c from the time of emission to the time of observation because light travels at a finite speed and A jogged a little further so the distance the light travelled was less than d when A eventually observed it.

Now A and B lock themselves up in the cabin of a ship and close all the windows. They stand a distance d apart and B signals A. How long is it from the time of emission to the time of the observation?

"Well, dumb-dumb," says Einstein to Newton, "it obviously has to be t=d/c because all that matters is how they describe things in their local frame of reference. I know it seems silly if you know that the ship's actually moving; but what's 'real' motion anyway? And I know the consequences are weird--there's no such thing as Now; time doesn't actually pass; there's no objective distinction between past, present, and future; etc.--but how could it be any different when you can't ever know whether the cabin is really moving or not. And you can't ever know whether the cabin is really moving or not."

Except you *can* know whether the cabin is really moving or not.

And while the theory *can* be used to describe everything that happens from any reference frame, because that's one of the basic principles that's in its design, you can't then turn around and use the fact as an argument that there's no such thing as "actual" motion, time doesn't actually pass, there's no "Now", and reality has to be described as a block universe. Logic doesn't work that way. It's like Ken Wharton wrote in his essay (he was referring to something else, but the argument still applies): it's like putting on rose-tinted glasses in order to justify claiming that the world is actually red.

It's been a hundred years, and hardly anyone will listen to Newton's muffled reply, "But all you have to do is look at the world around you to tell if you're really moving or not. I agree that you can describe everything that happens in a coordinate system in which you're "at rest"; but come on, Albert, open your eyes: the Earth is moving through the Universe at 370 km/s. There *is* an objective definition of motion, and therefore an objective definition of Now.

"Now, to get back to this business in which A and B are holed up in a cabin: if that cabin's actually moving--say along the line from A to B, in that direction--then after B signals A, A closes the distance a bit--i.e., the distance d between B and A at the time of emission, since A moves towards the point of emission and B moves away from it, so they maintain a constant relative distance from each other--so the actual time it takes the signal to get from B to A is t less than d/c. If you've got trouble with this, please refer to the above example where A is jogging towards B. It's the same thing."

I agree with Newton and disagree with Einstein. For these same reasons, I think Einstein's definition of simultaneity is wrong.

Daryl

Daryl

This is not what Einstein said. This is what people translate him as saying. What he meant to say was both correct and obvious (see below in respect of this paper that Eckard is referring to). The irony being that he had no observation, because there was nothing to observe with. So his c is not observational light, there are no frames of reference, etc, etc. His c is just a constant in order to calibrate distance and duration. This is why he then defines SR, in order to provide a circumstance within which the two 1905 postulates reconcile, before going on to GR.

So, yes in practice, the distance AB is irrelevant, because the distance travelled is from source (ie the position B was in at that time) to when the light is received, and A is moving towards it. But, as I said, Einstein did not have any observational light. He was, in effect, just measuring AB as is, when it exists, ie at a point in time. And that can be done two ways. Either one can establish the spatial difference. Or one can express the distance in terms of duration for something to travel it, like light at a constant speed. It cannot actually do this, because AB can only exist at one point in time, it being the spatial difference between two physically existent states.

Paul

Eckard

Re the essay you referred me to.

There is no synchronisation problem, or at least only at a practical level, which is an entirely different matter and not what Einstein was concerned with. Neither do timing devices have to be synchronised by signal exchanges.

His definition of Poincare/Einstein synchronization is wrong. Einstein did not say that clocks are synchronised by this method, in terms of telling the time, which is their function. He was saying that for them to indicate the time of occurrence of an event in any other spatial location, they would have to be synchronised this way. In other words, set out of synchronisation in order to compensate for the duration delay whilst light travels the distance between event and recipient of the light.

Einstein 1905 part 1 section 1:

"If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions of the hands which are simultaneous with these events. If there is at the point B of space another clock in all respects resembling the one at A, it is possible for an observer at B to determine the time values of events in the immediate neighbourhood of B. But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an "A time" and a "B time." We have not defined a common "time" for A and B, for the latter cannot be defined at all unless we establish by definition that the "time" required by light to travel from A to B equals the "time" it requires to travel from B to A".

His concept of "immediate proximity" is wrong, physically, as there is always a delay, but it is an understandable approximation. When not in whatever constitutes "immediate proximity", ie at B, the light from A will take some time to reach B (as opposed to at A where being in the "immediate proximity" is deemed to result in no time delay). In fact there is a time delay in all circumstances. So looking at the timing device at B will give a reading of time of theevent at A which is 'late', in terms of time of occurrence of that 'distant' event, as opposed to time of receipt of light repreentation thereof.

What he is supposed to be writing about is the receipt of a light representation of reality. But, apart from the incorrect approximation with the 'immediate proximity', he gets this wrong because the last caveat is incorrect. All he needs is the time taken for light to travel AB, under 'perfect conditions'. The 'common time' is only required for B in respect of A, or vice-versa, and it is not a 'common time' but an adjusted time taking into account the duration delay whilst light travels. In other words, discounting the different spatial position so that the reference is the same. And although he writes about clocks synchronising, what he means is that for the timing devices to, in any position, tell the time of the occurrence of an event in another spatial position, then they have to be adjusted to eliminate the time delay whilst light travels. He writes before this paragraph: "substituting "the position of the small hand of my watch" for "time." ". The word stationary, which is used throughout the section is superfluous.

The simple fact is that a reality occurs at a time. In doing so it generates physically existent light based representations of it, which in some cases are received, at a later time, depending on spatial position, and in real circumstances, physical conditions encountered. The timing system is about all devices showing the same time, ie being synchronised, in the proper sense of the word, within practical possibilities. That is the reference is one conceptual constant rate of change.

Paul

Eckard

Re the first postulate. We may have been talking at cross purposes. I am referring to the statement in the introduction, second paragraph. What does he actually write. You are referring to his statement at the start of section 2, part 1 (On the relativity of lengths and times).

Paul

Daryl

"this has to be a hyperbolic transformation"

? surely, it is just a matter(!) of relative spatial positions and timings of receipt of light. One could assume, to make it simpler, that all light travelled in the same physical circumstances.

Paul

Paul, that's not anything Newton said either. I said it.

But about Einstein, you're confusing two things. It's not just the first postulate that leads "him" to say what he says there, but the definition of simultaneity, as he did state it, because saying the time it takes light to cross the distance from A to B is equal to that distance divided by c is equivalent to making that definition of simultaneity.

Daryl

Paul,

It's not actually as complicated as it sounds. It's just another way of saying that the Lorentz transformation takes you from one frame to the other. The point I was really trying to get at was that by tilting the axes in that way, light is described as moving through space in time at the same rate in either direction, in both coordinate systems. But yes, in order to make that rate actually the same constant value in both coordinate systems, the axes do need to be rescaled in this way.

Daryl