## Events, Intervals and Speed

Discussions on classical and modern physics, quantum mechanics, particle physics, thermodynamics, general and special relativity, etc.

### Events, Intervals and Speed

This thread is a continuation of the long-standing debate on Faradave's "Interval speed", which again surfaced in rajnz00's Block Universe thread.

The core of the debate is contained in the following references.

1. Events
Burt Jordaan wrote:You have not answered where speed comes in for events with different, yet fixed spatial separation in each inertial frame. This (non-existent) "speed" is actually always zero…

Faradave » 14 May 2020, 21:35 wrote:I find that confusing. My home and the local convenience store have fixed spatial locations, yet I have a speed (∆x/∆t) going between them. If the store is in my home (∆x=0), my speed would be zero (as you say, a "non-existent speed") since I'm already there from the start.

Burt Jordaan wrote:Your home and your local convenience store are not events. Time ticks on for both. Spacetime intervals are defined in terms of events, for which neither space, nor time changes.

2. Speed
Faradave » 14 May 2020, 21:35 wrote:Spacetime events can have different spatial coordinates yet have zero interval (lightlike) separation. An absorber appears on the future light cone of its emitter. If I define interval speed as ∆d/∆t, when ∆d is zero (lightlike), the interval speed is indeed "non-existent" at zero. This also explains the "instantaneous" acceleration (to zero speed) of light quanta.
Wkipedia wrote:"In a light-like interval, ... events define a spacetime interval of zero ...the spacetime interval between two events on the world line of something moving at the speed of light is zero"

I construe this to mean the absorption event was already there at the emission event for a light quantum. Since ∆t is relative, the only interval speed (∆d/∆t) that all inertial observers agree on is 0/∆t, making c uniquely invariant. This also explains the instantaneous acceleration of light quanta. Physics offers no other explanation for the existence or invariance of speed limit c.

1. Spacetime events are unique occurrences at a specific place and a specific time. If properly drawn on a Minkowski spacetime diagram (Msd), an event is a single, static point in spacetime. Every conceivable inertial frame drawn on that same Msd, will use that single point as projected onto their respective space- and time axes in, order to establish the unique spatial (x,y,z) and time (t) coordinate of that event for that specific inertial frame.

Event A projected onto two inertial frames in relative motion

Since the two inertial frames are drawn with a common origin, the origin is usually taken as a common unique event at (0,0) for convenience, because its simplifies discussions and equations. It is important to emphasize that although the coordinates for an event are different in different inertial frames, it is static in spacetime for all inertial frames. It has happened, has been recorded in arbitrary many inertial frames and that's that.

2. The spacetime interval is a coordinate independent property that can be assigned to two Minkowski spacetime events, originating from the hyperbolic nature of Minkowski spacetime. It is obtained by squaring the time difference and the spatial difference between the two events (in any inertial frame) and then subtracting them. This gives the square of the invariant spacetime interval between the two events, as has been shown plenty of times in the referenced thread and numerous others. It is important to realize that the spacetime interval is not a distance.

When Faradave writes d² = (ct)² – x², it appears as if he intuit it as a distance of some sort, which is unfortunate. There is in fact a property related to spatial distance in SR, called the displacement four-vector, or four-displacement for short, defined as an arrow linking two events in 4-dimensional spacetime. It is patently not the spacetime interval and the spacetime interval is not a distance.

Based on this apparent misconception, Faradave then proceeds by equating the timelike interval (which is zero), to a zero separation between two events, e.g. emission and eventual absorption of a photon can happen 'instantaneously' over a distance. This then leads to the mysterious "interval speed" between two events, which are both static in space and time. Hence my repeated question: "where does speed come in?". One cannot even conceptualize any object to have speed relative to an event.

Apparently, the 'explanation' for the constancy of the speed of light and the "the instantaneous acceleration of light quanta" statement are also linked to this misconception.

The floor is open for discussion.

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### Re: Events, Intervals and Speed

BurtJordaan » May 15th, 2020, 6:57 am wrote:
It is patently not the spacetime interval and the spacetime interval is not a distance.

A spacetime interval is simultaneously a distance and a time as the name implies. Anything in our distance is also in our past and it works both ways. We are the past for any observer in our distance.
BurtJordaan » May 15th, 2020, 6:57 am wrote:
Hence my repeated question: "where does speed come in?". One cannot even conceptualize any object to have speed relative to an event.

Speed has nothing to do with it. I see no problem conceptualizing a speed relative to an event but one cannot conceptualize speed relative to a vacuum or a speed between two simultaneous events and light events are simultaneous at both signal and sink. However we can never see simultaneous events as simultaneous whenever there is a spacetime (space and time) interval separating them.

The “zero separation” between two light events is best considered as a superposition of two remote events where superposition is understood as a measurable transformation experienced by the detectors due to stimulations interactions induced by multiple waves simultaneously acting on the the detecting dipoles.

In other words, the interaction between the two light events is simultaneous at both ends and either instant or far too fast to measure. This understanding implies that the “motion” of light is cinematic like the moving letters on a signboard and it is not a “speed” through space.

The “multiple waves” in superposition are the wavelike background of space itself connecting the light source and sink before the instant exchange of light energy. This makes the presence of light, as either a particle or a wave, in the space between redundant to our understanding of light.

There is nothing in QM that requires a direct physical contact between two particles for one particle to interact with another particle no matter what the distance between them and this was first demonstrated by the experiments of Bell and Aspect.

Are you denying the possibility of a non-local “instant” interaction not involving speed wrt light?

These are two articles by N "Viv" Pope explaining the POAMS theory of light.

http://www.poams.org/wp-content/files/photon_fiasco.pdf
http://www.poams.org/what-is-light/
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### Re: Events, Intervals and Speed

What ‘queers the pitch’ is the concept of the light
quantum as a travelling particle called the ‘photon’. This makes trying to understand
quantum relativity like trying to fathom how a movie works in terms of something
having to ‘travel’ between the stills to create the phenomenon of motion. This is
because we usually think of a movie as an illusion created by a film camera taking
sequences of pictures which are no more than chunks out of what is really continuous
motion [2]. With this concept of underlying continuity stuck in our minds we can
scarcely contemplate the inverse of that concept, which is that on the ultimate
quantum level of physical analysis, it is the ‘chunks’ that are the reality and the
continuity the illusion.

I imagine part of the illusion's power is that we feel we may place a detector anywhere between emitter and absorber, this capability suggesting a continuum between them. Of course, there is no meaningful "original absorber, " only the absorber as the detector itself.

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### Re: Events, Intervals and Speed

I don't know why I am participating in this thread. But I just wanted to ask everyone else if my eyes are seeing what they apparently are seeing.

BurtJordaan has created a thread where he merely defines two neologisms in common physics textbooks.

1. The spacetime interval

2. the momentum four-vector.

I don't know why he is doing this , or if he is getting paid to be someone's physics tutor or what. But onward..

bangstrom has entered the thread. bangstrom briefly posted some incoherent gibberish about "wavelike background of space itself connecting the light source and sink". He then linked to some crackpot's website. This was a full throttled thread hijacking. The linked material has little or nothing at all to do with the lead post.

If I'm missing something, cue me in.

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### Re: Events, Intervals and Speed

hyksos » 16 May 2020, 06:37 wrote:
BurtJordaan has created a thread where he merely defines two neologisms in common physics textbooks.

1. The spacetime interval

2. the momentum four-vector.

I don't know why he is doing this , or if he is getting paid to be someone's physics tutor or what. But onward..

Hyksos, If you read the last page of the referenced thread and the OP properly, it should be clear why this one exists.

BTW, I did not discuss the momentum four-vector, but rather the four-displacement, because it is relevant to the issue discussed.

I agree with you on Bangstrom's linked material, especially after I have looked at the "about us" of the site:

http://www.poams.org/about wrote:This is an unusual cross-disciplinary merger of Physics and Philosophy in the grand manner of what used to be called Natural Philosophy.

However, in the spirit of open discussion, I think both Faradave's and Bangstrom's views are open for discussion in this thread. If it goes overboard, I can always transfer it to Personal Theories to save the canon.

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### Re: Events, Intervals and Speed

TheVat » 16 May 2020, 02:26 wrote:I imagine part of the illusion's power is that we feel we may place a detector anywhere between emitter and absorber, this capability suggesting a continuum between them. Of course, there is no meaningful "original absorber, " only the absorber as the detector itself.

We have many-many experiments and observations that indicate light is propagating through space.
One immediately jumps to my mind: the Shapiro tests of the gravitational time delay of light. A radar-type pulse was bounced off Venus when it was in opposition to the Sun. When it just grazed the Sun, the return pulses took 200 microseconds longer compared to when they missed the Sun by quite a bit.

Everything (Shapiro's and later refinements) fitted Einstein's prediction precisely, so the confidence in propagating e.m. waves is near 100%.

There are many other examples, e.g. gravitational lensing of distant quasars by intervening galaxies, effects of voids and clusters on the CMB redshift, etc.

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### Re: Events, Intervals and Speed

BurtJordaan » May 16th, 2020, 12:55 am wrote:
We have many-many experiments and observations that indicate light is propagating through space.
One immediately jumps to my mind: the Shapiro tests of the gravitational time delay of light.

The Shapiro tests lend support to GR and the gravitational lensing but I don’t see where they demonstrate the presence of light energy propagating through space. The delay in our observation of an EM signal is due to the the presence of both space and time “spacetime” between a signal source and receiver. The Shapiro effect includes the density of the gravitational field as a factor involved in increasing the amount of spacetime between a signal and receiver so we should observe a greater length of signal time whether light energy is passing through the observed space or not. The presence of light in space is an assumption in the Shapiro test- not an observation.

The question remains as to why we observe a time delay between a signal and receiver. I am saying the delay is explained by the presence of distance and time between the two which makes c a dimensional constant rather than a speed. Or c can be more precisely explained as it is found in Maxwell’s equations as the combined limiting effect of the magnetic permeability and the dielectric permittivity of space.

I find it more economical to attribute the c related delay in a light signal to the presence of spacetime between light events rather than the motion of light energy “photons” propagating through space. The two sources of time delay are mutually exclusive and the Shapiro delay is hard to comprehend if you have two competing sources time delay- gravitational lensing and the speed of light through space.
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### Re: Events, Intervals and Speed

I'm sorry to say Bangstrom, but I found what you wrote absolutely incomprehensible.

And sorry for being blunt, but let me point out that relativity gives a very precise positioning of the gradient of the space that "grows denser" and there is no other explanation for the additional time delay and the bending of light around massive objects than a wave which propagates through that region.

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### Re: Events, Intervals and Speed

BurtJordaan » May 15th, 2020, 10:55 pm wrote:
TheVat » 16 May 2020, 02:26 wrote:I imagine part of the illusion's power is that we feel we may place a detector anywhere between emitter and absorber, this capability suggesting a continuum between them. Of course, there is no meaningful "original absorber, " only the absorber as the detector itself.

We have many-many experiments and observations that indicate light is propagating through space.
One immediately jumps to my mind: the Shapiro tests of the gravitational time delay of light. A radar-type pulse was bounced off Venus when it was in opposition to the Sun. When it just grazed the Sun, the return pulses took 200 microseconds longer compared to when they missed the Sun by quite a bit.

Everything (Shapiro's and later refinements) fitted Einstein's prediction precisely, so the confidence in propagating e.m. waves is near 100%.

There are many other examples, e.g. gravitational lensing of distant quasars by intervening galaxies, effects of voids and clusters on the CMB redshift, etc.

Thanks. My tone was ironic, which perhaps didn't come across.

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### Re: Events, Intervals and Speed

BurtJordaan » May 16th, 2020, 8:30 am wrote:I'm sorry to say Bangstrom, but I found what you wrote absolutely incomprehensible.

And sorry for being blunt, but let me point out that relativity gives a very precise positioning of the gradient of the space that "grows denser" and there is no other explanation for the additional time delay and the bending of light around massive objects than a wave which propagates through that region.

Your comment is the point I was trying to explain. “Relativity gives a very precise positioning of the gradient of the space that "grows denser" and there is no other explanation for the additional time delay.”

Relativity explains the time delay in terms of curved spacetime in a denser gravitational field ignoring any effect on what that may have on the timing of a wave propagating through that region of what effectively has become a greater distance. The implication of this is that the time delay between a signal source and sink can be explained entirely by the amount of spacetime between the two and the speed of light has no effect on the timing of events. This is only possible if the speed of light contributes nothing to the timing as explained by GR’s curved spacetime which is only possible if the speed of light is instant.

To simplify things you can think of GR’s spacetime as a rubber band and the speed of light as an ant crawling from one end to the other. Stretching or contracting the rubber band should lengthen or shorten the time it takes the ant to cross. But, if the timing of events is solely determined by the length of the rubber band (GR’s spacetime) then the speed of the ant (speed of light) is irrelevant.
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### Re: Events, Intervals and Speed

bangstrom » 16 May 2020, 22:50 wrote:The implication of this is that the time delay between a signal source and sink can be explained entirely by the amount of spacetime between the two and the speed of light has no effect on the timing of events. This is only possible if the speed of light contributes nothing to the timing as explained by GR’s curved spacetime which is only possible if the speed of light is instant.

Hogwash! Please show a non-Vixra peer reviewed paper to support this claim.

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### Re: Events, Intervals and Speed: Dimensionality and Epstein

Part of the debate in the Block universe thread that has not been resolved, is the question of the dimensions of speed.

The international SI unit system gives the dimension m/s to speed. In relativity, most equations are written with ct in them, which implies that time is converted to meters. Then speed is dimensionless (m/m) and the speed of light becomes effectively unity, so one can leave the 'c' out of equations for economy of writing. We then speak of geometric, geometrical or geometrized units. This is common practice for relativistic spacetime diagrams from early times. Lately (1983) the meter has been defined[a] in terms of the speed of light, but that did not change the story.

What is important, is that we can view time as just another distance measure, so space-time becomes space-space, or 2-space in 2D diagrams.[b] This can be most vividly and geometrically pictured in an Epstein diagram, as below.

Epstein Scenario

The radius of the circle is 1 (unity) in any length unit that befits the problem at hand, be it Planck length, meters, light-seconds or billion light-years. Let's use light-seconds here, so that all clocks run in seconds.

Blue represents the Epstein coordinate system for the reference observer (Bob) and red the Epstein coordinate system for observer Alice, moving inertially at speed +0.6 relative to Bob. Each of them has a partner, say Dot and Cor respectively, who are stationary in their respective frames at a distance 1.0 from their partners.

Assume that all four clocks have been Einstein-synchronized sometime in the past in such a way that they all show zero when Alice and Bob pass the origin, just as a light flashes there. In 2-space Epstein coordinates, the light front[c] spreads out in a circle and reaches both Cor and Dot when their clocks read one second. Cor and Dot observes different parts of the light front, at the tips of the blue and red dashed arrows respectively.

This illustrates an important aspect of Epstein 2-space - the propagation of light is always shown at right angles to the world-lines of the observers that are not moving in the x-direction in that frame. This gives an excellent geometrical idea of the equivalence of inertial frames and how light seems to have the same propagation speed in each frame.

It is also immediately obvious that light-like spacetime intervals do not collapse into a null on the diagram. They are represented by the blue and the red dashed arrows and is therefore specific to each of the inertial frames. The usual equation for the interval applies. Bob reads his clock at the emission event of the e.m. wave and Pam reads her synchronized clock at the reception event. With △x=1 known, it is easy to see that △S2 = 12 - 12 = 0. Alice and Cor will obviously find the exact same zero result for the light-like interval in their inertial frame, albeit for a different portion of the light-front.

Now on to time-like intervals, which has the unique characteristic that a physical clock can depart at propertime Ƭ1 and arrive at propertime Ƭ2 and hence be present at both events. For example Alice and her clock are present at events E1 and E4, so she read the proper time interval between E1 and E4 as △Ƭ = Ƭ2 - Ƭ1. Since Alice did not change spatial coordinates in her own frame, the space-interval between the two events is zero. Hence the spacetime interval E4-E1 is △S = △Ƭ - 0 = △Ƭ = 1 sec for the example depicted.

I am laboring this to try and dispel Faradave's notion of 'interval speed' once and for all. There is no speed involved in the spacetime interval. The fact that Alice has changed spatial position relative to Bob is immaterial, because she has also changed spatial position relative a zillion other potential observers. If one insists on calculating a speed for the interval, it is zero/propertime = 0. IMO, it is meaningless.

Notes

[a] https://en.wikipedia.org/wiki/Speed_of_light#Numerical_value,_notation,_and_units

[b] In the real world, spacetime obviously becomes 4-space.

[c] There are no photons in relativity, so light propagates as a real e.m. wave.

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### Re: Events, Intervals and Speed: Dimensionality and Epstein

BurtJordaan » 17 May 2020, 10:37 wrote:I am laboring this to try and dispel Faradave's notion of 'interval speed' once and for all. There is no speed involved in the spacetime interval. The fact that Alice has changed spatial position relative to Bob is immaterial, because she has also changed spatial position relative a zillion other potential observers. If one insists on calculating a speed for the interval, it is zero/propertime = 0. IMO, it is meaningless.

One question that does remain is Faradave's concept of 'interval-time coordinates'. Is it meaningful in general? And if meaningful, is it useful?

As we have seen above, the spacetime interval between two time-like events equals the propertime interval between the two events, as measured by a clock that has moved inertially between the two events, say E4 and E1. Faradave wants interval-time coordinates, so I can only see two potentially meaningful coordinate systems.

1. Plot Alice's cumulative propertime against Bob's cumulative coordinate time for a specific relative speed, which is effectively the same as the Epstein diagram, just with the axes labeled differently.

2. Plot the ratio of propertime to coordinate time against a range of relative speeds say v from 0 to 1.0. This is a plot of the inverse Lorentz factor, which gives the same semi-circle as the top-right quarter of the Epstein diagram's unit circle.

Maybe there are other meaningful plots...?

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### Re: Eventuality

Jorrie, Thanks for taking the trouble to open this new thread. I thought I'd get my bearings before entering.

BurtJordaan OP wrote:1. …an event is a single, static point in spacetime. Every conceivable inertial frame drawn on that same Msd, will use that single point
Yes! But you must grant than a non-Euclidean system forced on a Euclidean map will have potentially large distortions. A single event in spacetime may thus appear as a line on such a map (e.g. the south pole on a Mercator projection). That seems central to our dissonance. Thus, my repetitions, much to the dismay of poor hyksos.

BurtJordaan OP wrote:1. …unique spatial (x,y,z) and time (t) coordinate of that event…
Case in point (literally). Even in a particular inertial frame, a single spacetime event may have infinite unique coordinate designations. In its proper geometry (a sphere), all observers agree that earth's south pole is a single geographic location with infinite (longitudinal) coordinate designations. Your apparently Euclidean avatar may affect your intuition on this.

BurtJordaan OP wrote:1. …event … in different inertial frames, it is static in spacetime for all inertial frames…
Yes. Spacetime events are fixed. Worldlines span many events but neither the events (nor the worldlines) move. Static worldlines may represent the classical motion of objects, such as particles.

BurtJordaan wrote:2. …It is important to realize that the spacetime interval is not a distance.
Too vague! An invariant interval is NOT a spatial distance. It IS a "4D separation" of the events which define it. Interval separation may be given in spatial or temporal units.

"In four-dimensional spacetime, the analog to distance is the interval." – spacetime interval

"This quantity is therefore something which, like distance, is "real" in some sense [earlier he mentions 'independent of coordinate system']; it is called the interval between the two spacetime points" – Feynman p.97

BurtJordaan OP wrote:2. the displacement four-vector
This seems like obfuscation or desperation, making things harder than they need to be. Feynman uses 4-momentum to derive Einstein’s energy formula (nice). An interval magnitude lacks direction (thus, not a vector). But it becomes a 4-vector when I provide direction in stating, "from emission event to absorption event".

BurtJordaan » May 14th, 2020, 5:34 pm wrote: Jorrie: Your home and your local convenience store are not events. Time ticks on for both. Spacetime intervals are defined in terms of events, for which neither space, nor time changes.
This is exactly what I mean. You should have well understood me to mean a trip from my home now to the store at ∆t. Both are then indeed 4D events, though I only intended an analogy.

BurtJordaan OP wrote:2. Faradave then proceeds by equating the timelike interval (which is zero), to a zero separation between two events, e.g. emission and eventual absorption of a photon can happen 'instantaneously' over a distance.
Let's fix this.
We are referring to a "lightlike" interval which has magnitude zero (a simple typo).
I equate that to zero "4D separation" between events.
An electron orbital transition is essentially instantaneous. Transmission of the quantum from emitter to absorber IS instantaneous in the inertial frame of the quantum – but convention holds that frame "invalid" (I prefer merely "degenerate"). Certainly, in the inertial frame of any real observer the transmission would be the measured spatial separation (∆x) divided by measured transmission time (∆t) in the ratio c.

BurtJordaan wrote:What is important, is that we can view time as just another distance measure, so space-time becomes space-space, or 2-space in 2D diagrams.
Nice review. I've already conceded this.

However, it's one thing to find, for example, in Einstein's light clock derivation the expression: √(1-v²/c²) and replace v/c with u, as fractional lightspeed, i.e. √(1-u²). It's quite another thing to find: f(v) = √(c²-v²) and make it √[(c²-v²)/c²] without also dividing f(v) by c thus, changing it. Of course, we agree.

BurtJordaan wrote:an important aspect of Epstein 2-space …It is also immediately obvious that light-like spacetime intervals do not collapse into a null on the diagram. They are represented by the blue and the red dashed arrows and is therefore specific to each of the inertial frames. …There are no photons in relativity, so light propagates as a real e.m. wave.
It's also important to recall Epstein's admission that he flubbed representing light, especially a single photon. Fields and EM wave nature are a different topic. The photo-electric effect demands the particle aspect of light, which I address.

BurtJordaan wrote:I am laboring this to try and dispel Faradave's notion of 'interval speed' once and for all.
I'll pause before addressing "interval speed". You're way over thinking it. Rest assured, we agree with SR that events and worldlines are fixed (Block Universe debate notwithstanding).

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### Re: Events, Intervals and Speed

BurtJordaan » May 16th, 2020, 10:54 pm wrote:
bangstrom » 16 May 2020, 22:50 wrote:The implication of this is that the time delay between a signal source and sink can be explained entirely by the amount of spacetime between the two and the speed of light has no effect on the timing of events. This is only possible if the speed of light contributes nothing to the timing as explained by GR’s curved spacetime which is only possible if the speed of light is instant.

Hogwash! Please show a non-Vixra peer reviewed paper to support this claim.

Could you mention what you consider "hogwash."

I presume your main complaint is with my comment about the speed of light being instant. The “speed of light” is measured to be c and I see two possible explanations for the result. One is that it truly is the speed of light and the other is that c is a dimensional constant giving us the amount of time present in any given distance. So, if the true speed of light is instant and c is a dimensional constant, we can never observe light as instant because our 3D environment always includes a c related interval of both space and time between any two points.

The observation that favors the latter point of view is that all observers measure c to be the same which suggests it is a universal dimensional constant rather than speed. If it were a speed it should be measured differently by observers in different reference frames.

My justification for considering c to be a dimensional constant comes from Minkowski’s diagrams where c is treated as a dimensional constant where every square of distance includes an amount of time such that the ratio of distance to time is equal to c. And GR where c is also used as a dimensional constant even though it may not be explained that way.

My quick and simple explanation is that the use of c in relativity works as a dimensional constant where the speed of light is instant and the observed amount of space and time “spacetime” between any two remote points is equal to 300,000 km/sec. So the instant nature of light contributes nothing to our observation of time.
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### Re: Events, Intervals and Speed

Faradave » 17 May 2020, 20:24 wrote:
BurtJordaan OP wrote:1. …an event is a single, static point in spacetime. Every conceivable inertial frame drawn on that same Msd, will use that single point

Yes! But you must grant than a non-Euclidean system forced on a Euclidean map will have potentially large distortions. A single event in spacetime may thus appear as a line on such a map (e.g. the south pole on a Mercator projection).

What you and I are doing is searching for alternative diagramming in order to make it more intuitive, but this cannot alter the inherent principles of physics.
Fd wrote:
BurtJordaan OP wrote:1. …unique spatial (x,y,z) and time (t) coordinate of that event…

Case in point (literally). Even in a particular inertial frame, a single spacetime event may have infinite unique coordinate designations. In its proper geometry (a sphere), all observers agree that earth's south pole is a single geographic location with infinite (longitudinal) coordinate designations.

The applicability of SR is limited to flat spacetime, so I disagree. In a particular inertial frame, a single spacetime event may not have infinite unique coordinate designations.
Fd wrote:
BurtJordaan OP wrote:2. the displacement four-vector

This seems like obfuscation or desperation, making things harder than they need to be.

I have a problem with many of your out of context little quotes. The context of my reply was:

Burt wrote:When Faradave writes d² = (ct)² – x², it appears as if he intuit it as a distance of some sort, which is unfortunate. There is in fact a property related to spatial distance in SR, called the displacement four-vector, or four-displacement for short, defined as an arrow linking two events in 4-dimensional spacetime. It is patently not the spacetime interval and the spacetime interval is not a distance.

The displacement four-vector correlates to the worldline of an observer and will become important in these discussions.

Fd wrote:We are referring to a "lightlike" interval which has magnitude zero ...
I equate that to zero "4D separation" between events.

This is where the fundamental disagreement starts. You define a "4D separation" and equate it to a light-like interval. From that it is an easy step to define "4D contact", but without a very tangible physical example. The electron jumping orbitals does not cut it, because IMO, it does not have to jump anywhere. It can merely change its wavelength to the next longer or shorter de Broglie wavelength available for its parent atom.

This happen when it emits or absorbs one or more quanta of energy. I'm not knowledgeable on atomic physics, so this is just my way of staying sane. But it is quite reasonable to say that such an event is instantaneous, because it is strictly local. An emitted quantum spreads out at the speed of light relative to the atom and its eventual absorption (event) by a distant atom is again instantaneous and local. But the two events, emission and absorption, are not "instantaneous", or rather simultaneous in any inertial frame whatsoever.

You postulated "pinholes" and other alike things (in other posts and writings) to try and overcome this, but your reasoning behind them is suspect IMO - and apparently also in the opinions of other experts.

"4D contact" is really at the core of our disagreements.

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### Re: Events, Intervals and Speed

bangstrom » 17 May 2020, 20:45 wrote:Could you mention what you consider "hogwash."

Pretty much what I have quoted. This was an extraordinary claim and would require a similar level of proof. I have never seen any of that.

The curvature of spacetime is propagated by gravitational waves, at speed c relative to the source and relative to any detector of those GWs. Spacetime curvature has been set up as a changing gravitational field right after inflation, or whatever started the expansion.

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### Re: Events, Intervals and Speed

BurtJordaan » May 18th, 2020, 5:20 am wrote:
bangstrom » 17 May 2020, 20:45 wrote:Could you mention what you consider "hogwash."

Pretty much what I have quoted. This was an extraordinary claim and would require a similar level of proof. I have never seen any of that.

The curvature of spacetime is propagated by gravitational waves, at speed c relative to the source and relative to any detector of those GWs. Spacetime curvature has been set up as a changing gravitational field right after inflation, or whatever started the expansion.

We know the value of c with a great deal of accuracy but is c the speed of light or is it a dimensional constant?

Cosmological determinations of of c tell us that c is a ratio and a conversion factor for converting between units of time and distance. It is not necessarily a speed just because it is in units of distance over time. c is used and it works as a dimensional constant but it acts nothing like a speed.

BurtJordaan » May 17th, 2020, 3:37 am wrote:
Lately (1983) the meter has been defined[a] in terms of the speed of light, but that did not change the story.

The meter is defined as the distance light travels in 1/c seconds. This illustrates the impossibility of trying to measure the speed of light. Any attempt to measure the speed of light is, on the lesser scale, an attempt to measure the speed of light over the distance of a light year. Our standard units of measure are mutually defined as values of c. The length of a second is defined as the time it takes light to travel 1/c meters and measured as wavelengths of a cesium microwave emission or whatever wavelength they are using now.
You can’t measure c in units defined by c because it will only return the same value you put in.

BurtJordaan » May 17th, 2020, 3:37 am wrote:
What is important, is that we can view time as just another distance measure, so space-time becomes space-space, or 2-space in 2D diagrams.[b] This can be most vividly and geometrically pictured in an Epstein diagram, as below.
EpsteinAliceCorSmall.png

This is worth repeating. “ What is important, is that we can view time as just another distance measure.” With measurements for light, c is a constant ratio of distance/ time.
Also with light, time is symmetric. We emit light into the future and receive light from the past. Your Epstein scenario should work when viewed as either time running forward or backward. The emission of light can be visualized as time moving forward and the reception of light can be visualized as the simple reverse.
BurtJordaan » May 17th, 2020, 3:37 am wrote:
It is also immediately obvious that light-like spacetime intervals do not collapse into a null on the diagram.

The order is in reverse. Spacetime intervals begin as null and collapse when observed. For any observer, the spacetime intervals extend into the past and exist as history.
That may make no sense to you now but keep it in mind because light is time-symmetric and you may understand it later.
BurtJordaan » May 17th, 2020, 3:37 am wrote:I am laboring this to try and dispel Faradave's notion of 'interval speed' once and for all. There is no speed involved in the spacetime interval. The fact that Alice has changed spatial position relative to Bob is immaterial, because she has also changed spatial position relative a zillion other potential observers. If one insists on calculating a speed for the interval, it is zero/propertime = 0. IMO, it is meaningless.

The meaning of zero propertime is that a light signal reaches all observers instantly rather than propagating through space as you describe and many in the past have done. What the several observers see is light from the past through the filter of 3D spacetime. I admit that view takes a lot of getting used to- it did for me- but that is the timing of the interaction observed in experiments with light.

Here is another consideration. A gravitational field increases the spacetime separation between remote points and we observe a greater time delay between the light signal and receiver as described by GR because the distance is greater. The time is longer and the distance is longer but the ratio between the two is always c.

If a light wave passes through space, the light should be slowed by gravity as well as being slowed by the greater amount of spacetime so a light wave should take longer to get from A to B if it travels through space (and gravity) rather than an instant transmission. That is one clue telling us that light does not exist between signal and source.

Try to understand what Faradave is saying before you labor so hard to dispell it.
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### Re: Events, Intervals and Speed

BurtJordaan » May 18th, 2020, 3:35 am wrote: The electron jumping orbitals does not cut it, because IMO, it does not have to jump anywhere. It can merely change its wavelength to the next longer or shorter de Broglie wavelength available for its parent atom.

In QM, electrons jump orbits instantly without passing through the space between. Energy is considered to be able to swap locations but, contrary a popular misconception, energy does not exist separate from matter. The electron in an atom does change to a longer or shorter wavelength as you said and in doing so it jumps to another orbit.

BurtJordaan » May 18th, 2020, 3:35 am wrote:
This happen when it emits or absorbs one or more quanta of energy.

NO, no, no. Forget the emits part. Energy does not emit from matter. The event is instant and local but the non-local part happens when a separate, and possibly extremely remote, electron simultaneously gains or loses precisely the same amount of energy so energy is conserved.
A non-local, wavelike connection is established between the electrons before the energy transfer takes place
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### Re: Events, Intervals and Speed

That last sentence sounds disturbingly like electron romance followed by electron sex.

Whew. My glasses are all steamed up!

Seriously, I would be grateful for a clearer explication of what is meant by a "wavelike connection. " And how wavelike connectedness can possibly not involve energy transfer.

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### Re: Events, Intervals and Speed

bangstrom » 18 May 2020, 19:45 wrote:In QM, electrons jump orbits instantly without passing through the space between. Energy is considered to be able to swap locations but, contrary a popular misconception, energy does not exist separate from matter. The electron in an atom does change to a longer or shorter wavelength as you said and in doing so it jumps to another orbit.

In QM electron orbitals are not orbits with a specific radius. Just a smeared out probability cloud wherein different orbitals exist.

BurtJordaan » May 18th, 2020, 3:35 am wrote:
This happen when it emits or absorbs one or more quanta of energy.

bangstrom » 18 May 2020, 19:45 wrote:NO, no, no. Forget the emits part. Energy does not emit from matter. The event is instant and local but the non-local part happens when a separate, and possibly extremely remote, electron simultaneously gains or loses precisely the same amount of energy so energy is conserved.

Huh? I trust that you have a reliable reference for this?

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### Re: Events, Intervals and Speed

bangstrom » 18 May 2020, 18:15 wrote:We know the value of c with a great deal of accuracy but is c the speed of light or is it a dimensional constant?

Not quite a dimensional constant - c is a constant of nature. The two-way speed of light in vacuum happens to be equal to, or extremely close to c, as established by observation. The one-way speed of light follows from the definition of simultaneity, i.e. by convention. https://www.livescience.com/29111-speed-of-light-not-constant.html

No comment on the rest of your post.

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### Re: Events, Intervals and Speed

TheVat » May 18th, 2020, 1:07 pm wrote:That last sentence sounds disturbingly like electron romance followed by electron sex.

Whew. My glasses are all steamed up!

Seriously, I would be grateful for a clearer explication of what is meant by a "wavelike connection. " And how wavelike connectedness can possibly not involve energy transfer.

The wavelike connection is essentially the Schroedinger wave going both forward and backward in time. https://en.wikipedia.org/wiki/Transacti ... rpretation

More information about the wavelike hook-up can be found in John Cramer’s Transactional Interpretation of Quantum Mechanics TIQM. This is a heavy read for those not familiar with the subject. He describes the transaction as a “handshake” with a picture of Feynman and Dirac shaking hands. Cramer writes in words borrowed from classical light theory to be as inoffensive as possible for innocent readers so you often have to read between the lines to follow what he is saying. Ruth Kastner has some nice videos about Cramer’s TIQM.

There is a non-local energy transfer. That is, the energy goes instantly from electron to electron without passing through the space between.

I could suggest a few easy pieces for the unexperienced but they are probably too kinky for this forum.
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### Re: Events, Intervals and Speed

BurtJordaan » May 18th, 2020, 3:38 pm wrote:
In QM electron orbitals are not orbits with a specific radius. Just a smeared out probability cloud wherein different orbitals exist.

That's right.

BurtJordaan » May 18th, 2020, 3:35 am wrote:
This happen when it emits or absorbs one or more quanta of energy.
bangstrom » 18 May 2020, 19:45 wrote:NO, no, no. Forget the emits part. Energy does not emit from matter. The event is instant and local but the non-local part happens when a separate, and possibly extremely remote, electron simultaneously gains or loses precisely the same amount of energy so energy is conserved.

Huh? I trust that you have a reliable reference for this?

Two extensive sources are John Cramer's TIQM and Carver Mead's "Collective Electrodynamics" The latter has a chapter about the non-local energy transfer among atoms in superposition that does not involve energy traveling through the space between. Part 5." Electrodynamic Interaction of Atoms."

I also posted a reference earlier from Carver Mead that included these points.
https://www.cns.caltech.edu/people/facu ... hotons.pdf

3. Every element of matter is coupled to all other matter on its light cone by time-symmetric interactions.
4. Matter interacts directly with other matter. The time-symmetric nature of these interactions make them effectively instantaneous.
10. A “photon” can be best viewed as a transaction between two atoms on the same light cone. Such a transaction requires an exquisite degree of phase matching between the quantum states of the two coupled atoms, and is therefore a rare event. Photon statistics result from the chance correlations of atomic wave function phases.
11. The “photon” transaction can be viewed as a brief entanglement of the quantum states of the two participating atoms.
12. The transaction is itself a completely continuous process. When a transaction is initiated, it grows exponentially with time. This highly nonlinear evolution gives the appearance of an abrupt “quantum jump”as the atomic wave functions “collapse”.
13. The observed particulate “photon” behavior is not due to the nature of fields,but is a manifestation of entropy, related to the thermodynamic arrow of time.
14. It is centrally important for a theory to be logically consistent.15.
17. The successes in technological enterprise are attributable to conceptual reasoning.“Fundamental” physical theory, as taught in universities and and propagated in the literature,has a long history of hindering conceptual reasoning, and therefore technological progress.
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### Re: Events, Intervals and Speed

bangstrom » May 19th, 2020, 1:47 am wrote:12. The transaction is itself a completely continuous process. When a transaction is initiated, it grows exponentially with time. This highly nonlinear evolution gives the appearance of an abrupt “quantum jump”as the atomic wave functions “collapse”.

How is this compatible with an instantaneous process?
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### Re: Events, Intervals and Speed

@bangstrom: I am also a fan of Cramer's Transactional interpretation. It is worth reading one of his later papers on the subject:

Quantifying Absorption in the Transactional Interpretation
R. E. Kastner, John G. Cramer https://arxiv.org/abs/1711.04501

I quote an extract from the Conclusions, page 10

Kastner, Cramer 2018 wrote:It is shown herein that emission and absorption processes are quantitatively well-defined in the transactional (direct-action) picture, and are essentially the same as in the standard theory of quantum electrodynamics, except for the replacement of the quantized field by the response of charged currents jj to an emitting current ji. Such emissions and responses cannot be predicted–they are inherently indeterministic. But the physical circumstances of their occurrence can be defined and quantified by identifying the coupling constant between interacting fields (e in the case of the electromagnetic interaction) as the amplitude for generation of an OW (Fock state |ki) or CW (dual Fock state hk| ), both being required for the existence of a ‘real photon,’ which in the direct-action picture is described by a Fock state projection operator |kihk.

Virtual photons are identified as the basic time-symmetric connections or propagators between currents, which do not prompt responses, do not precipitate the non-unitary transition, and thus remain an aspect of unitary (force-based) interactions only. Thus, virtual photons (time-symmetric propagator) convey force only, while real photons (projection operators, quanta of a real-valued field) convey real energy and break linearity. The latter is just an expression of what Einstein noted long ago: real electromagnetic energy (the actualized photon) is emitted and absorbed as a particle (projection operator with definite spatial momentum).
.

I think you are confusing the virtual transaction that happens through virtual photons and is therefore instantaneous, with the real transaction involving real photons that transfers the energy by propagating real waves through space and time.

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### Re: Events, Intervals and Speed

BurtJordaan » 18 May 2020, 10:35 wrote:"4D contact" is really at the core of our disagreements.

Is it just possible that you are contemplating this form of contact through mechanisms of the virtual transactions of Cramer's Relativistic Transactional Interpretation?

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### Re: Events, Intervals and Speed

Positor » May 19th, 2020, 12:08 am wrote:
bangstrom » May 19th, 2020, 1:47 am wrote:12. The transaction is itself a completely continuous process. When a transaction is initiated, it grows exponentially with time. This highly nonlinear evolution gives the appearance of an abrupt “quantum jump”as the atomic wave functions “collapse”.

How is this compatible with an instantaneous process?

This means that when two or more electrons are in a state of superposition it takes a little foreplay before their resonant states come together in a simultaneous climax resulting in an instantaneous transfer of energy.

Carver Mead discovered in his experiments with electrons in superconducting coils that, when an external electric field is applied to a current, the momentum of the electrons increases geometrically rather than linearly which one should expect..

Mead takes about three pages of explanations and equations borrowed from the Wheeler-Feynman Absorber theory to explain what is happening. It is my understanding that the W-F duo tried to calculate what happens when an electron in an atom loses energy and their calculations ended with infinities indicating that the electron’s lowest energy orbit should collapse into the nucleus.

The infinities were removed by solving the equations in 4D space using the Riemann-Sommerfeld differential. This shifts the problem being local to cosmological where single electrons can collectively share their momentum with other atoms on their light cone which never allows their orbits to totally collapse.
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### Re: Events, Intervals and Speed

BurtJordaan » 19 May 2020, 09:24 wrote:[@bangstrom]I think you are confusing the virtual transaction that happens through virtual photons and is therefore instantaneous, with the real transaction involving real photons that transfers the energy by propagating real waves through space and time.

This little animation is worth a thousand posts :-)

Dr. Ruth Kastner is apparently standing by her revision to the RTI theory, as evident in this recent interview on 'New Thinking Allowed'.

A bit drawn-out by host Jeffrey Mishlove, a "Parapsychologist", but from about the 32nd min, it deals with RTI in a physological way.
Last edited by BurtJordaan on May 19th, 2020, 6:51 am, edited 2 times in total.

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### Re: Events, Intervals and Speed

The Bob & Alice Story
A Ralf Entertainment Production

Once upon a time...

https://app.box.com/s/yt9x9y2vakdm01h99p6aepc16t87uhd7

On the left, Alice (green) speeds away from Bob at .6c, at Bt=At=0, sending a light pulse (blue) forward, to get a reading from her 2nd clock at 4 units distant.
Alice also sends a pulse at At=2, to get a clock reading from B.
Both pulses return to her at At=8, as indicated by the red calibration curve (Max Born).

Bob's (x, t) coordinates for Alice detects the return pulses are (6, 10).
Bob's (x, t) coordinates for R are (8, 8).
Bob's description includes time dilation (td) and length contraction (lc) of the A-frame.

Alice's (x, t) coordinates for the return pulses are (0, 8).
Alice concludes Bob is only 8*(.6)=4.8 units distant, and a marker in the B-frame indicating 8 units is only 6.4 units distant.
Alice assigns At=5 to Bt=4.
Alice's description includes time (td) and (lc) of the B-frame.
The Minkowski spacetime graphics provide a geometric means of applying the coordinate transformations.
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