Cramer's Transactional Interpretation.

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Cramer's Transactional Interpretation.

Postby hyksos on November 21st, 2019, 2:26 pm 

Okay we have a thread on CTI now.

My purpose for starting up a thread on the Transactional Interpretation of Quantum Mechanics -- mostly for purposes of criticizing and critique. Some random observations ...

1.
CTI claims to resolve retrocausality. (In particular the retrocausal paradoxes of QM) However does so by invoking copious amounts of retrocausal phenomena with backwards-in-time moving waves. I'm not completely sure you can resolve retrocausality by embracing retrocausality in everything.

2.
CTI bends the word determinism to its breaking point. We know what a mathematician means when he says

X uniquely determines Y.

The determination is not meant to unfold mechanically in space and time, like a calculation, but instead means something like "there exists a functional association between" X and Y in a world of deduction. Saying that a future event "determines" a physical event in the present, doesn't really mean "determine" in the sense of Laplace. Not the kind of gear-A-turns-gear-B determinism we normally associate with matter/substance.

3.
CTI might be argumentum ad mysterium. It might be approaching the measurement problem and not addressing it head on. I worry (this is my opinion of course) that CTI is moving the measurement problem to a backburner. While we seem to have found a source of determinism for a present spacetime event, the mystery is "outsourced" to a fuzzy future state which is seductively mysterious enough to be believably undetermined.

Your thoughts?
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Re: Cramer's Transactional Interpretation.

Postby hyksos on November 21st, 2019, 2:30 pm 

4.
CTI definitively asserts that the future definitely physically exists. Anything argument about the future "not yet manifest" cannot exist in CTI. Blustering over that topic seems either unwise or unscrupulous. Whole multipage threads on this forum have been spilt on that topic alone. Seems hasty to just accept it as easily as we would change into a different pair of socks.
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on November 22nd, 2019, 6:42 am 

hyksos » November 21st, 2019, 1:30 pm wrote:4.
CTI definitively asserts that the future definitely physically exists. Anything argument about the future "not yet manifest" cannot exist in CTI. Blustering over that topic seems either unwise or unscrupulous. Whole multipage threads on this forum have been spilt on that topic alone. Seems hasty to just accept it as easily as we would change into a different pair of socks.


My understanding of CTI is that particles in our local surroundings can interact non-locally in a wavelike manner with particles at remote distances which is what we observe with the retrocausal paradoxes of QM. So anything distant from us lies in our future, and from the other perspective, we are a part of the future for the material world that lies at a distance from us.

This means that interacting particles are in direct quantum contact despite their observational separation so that, at the quantum level, there is no such thing as distance. What we see as “distance” is a statistical readout of instantaneous non-local events separated by space and time. As the old saying goes, time is Nature’s way of keeping everything from happening at once and space is Nature’s way of keeping everything from happening in the same place.

I think of retrocausality in CTI as limited to particles but not necessarily “everything” above the particle level. And the “future” as limited to those particles remote from our own rather than something “not yet manifest” since our local particles are what interact non-locally (instantly) with the rest of the physical universe and vice versa.
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Re: Cramer's Transactional Interpretation.

Postby TheVat on November 22nd, 2019, 1:43 pm 

This means that interacting particles are in direct quantum contact despite their observational separation so that, at the quantum level, there is no such thing as distance. What we see as “distance” is a statistical readout of instantaneous non-local events separated by space and time. As the old saying goes, time is Nature’s way of keeping everything from happening at once and space is Nature’s way of keeping everything from happening in the same place.


Good ol' Wheeler, right? Man had a way with words. I still find it confusing to say there's no such thing as distance at a certain "level." If events are separated by space, then they are at a distance from each other. That is what "distance" means. If observation is to mean anything, it means that we are observing distances. IF someone wants to say that, at the "quantum level," the photosphere of the Sun is in their living room, that's all very poetic but it doesn't do much to make sense of quantum theory.
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on November 22nd, 2019, 8:05 pm 

TheVat » November 22nd, 2019, 12:43 pm wrote:
Good ol' Wheeler, right? Man had a way with words. I still find it confusing to say there's no such thing as distance at a certain "level." If events are separated by space, then they are at a distance from each other. That is what "distance" means. If observation is to mean anything, it means that we are observing distances. IF someone wants to say that, at the "quantum level," the photosphere of the Sun is in their living room, that's all very poetic but it doesn't do much to make sense of quantum theory.

Observations at the macro level do not necessarily apply at the quantum particle level because macro objects are massive collections of quantum particles so what we observe are the collective averages of particles and not necessarily what may be happening with every individual particle. This is collectively known as quantum wierdness.

We may observe distances between objects at the macro level, but at the quantum level, separation is not a persistent phenomenon and widely separated particles can momentarily interact as if they are parts of a single whole. Non-local interaction where distance no longer matters is one example of this wierdness.
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Re: Cramer's Transactional Interpretation.

Postby hyksos on November 23rd, 2019, 6:19 pm 

My understanding of CTI is that particles in our local surroundings can interact non-locally in a wavelike manner with particles at remote distances

That is not CTI. You just described regular entanglement.

So anything distant from us lies in our future, and from the other perspective, we are a part of the future for the material world that lies at a distance from us.

\hat you are attempting to describe with distant spacetime points being "in our future" is just the normal phenomenon of a wave approaching us from the distance place in the regular expand-out manner. Stuffy grad students call it the "future lightcone".

Secondly, it is definitely not CTI. CTI explicitly has waves that move backwards in time, and to a normal human observer, these A-waves would look like an explosion in reverse. They begin spread out over the environment, then coalesce to a point. This is a specific ontological commitment in CTI.

This means that interacting particles are in direct quantum contact despite their observational separation so that, at the quantum level, there is no such thing as distance.

That doesn't follow from CTI at all. I have never in my life seen "Direct quantum contact" mentioned in any article on Interpretations of QM in my entire life. The only place I've ever seen that phrase used is in Faradave's posts on this forum.

Your description of "no space" can be demonstrated false in simple lab experiment. When a quantum system is measured, it gives us actual values every time. When engineers are trying to build a quantum computer, this problem is called decoherence, and it annoys the hell out of them. The entangled qubits will "collapse" into their own little deterministic states if any kind of heat or disturbance sneaks into the computer. Once collapsed they can no longer leverage the non-local interactions that give them the special powers to compute.

Decoherence is the reason numero uno that we don't have quantum computers in our living rooms.

What we see as “distance” is a statistical readout of instantaneous non-local events separated by space and time. As the old saying goes, time is Nature’s way of keeping everything from happening at once and space is Nature’s way of keeping everything from happening in the same place.

I don't see how this applies. What you are describing is true of the unitary wave evolution -- that strange moment when nobody looks at matter. But this universe has measurement, wherein unitary wave evolution is suddenly stopped by measurement, and genuine particle properties are observed.

There are many different reasons for engaging with Interpretations of QM. (I'm not going to list them.) One of them is to resolve the Measurement Problem. It seems to me from all I have read that CTI is an attempt to resolve the Measurement Problem.

The question was posed in the narrative about the physics professor at Princeton in his office. A photon at a shallow angle to the glass window can reflect or transmit at a 50/50 chance. What in the universe causes the decision?

I agree wholeheartedly with non-local interactions, but those are insufficient at explaining why we physically observed that particular outcome.

I think of retrocausality in CTI as limited to particles but not necessarily “everything” above the particle level.

We are perfectly satisfied when we have uncovered what looks like a deterministic cause for the photon's decision at the glass window surface. But CTI is suggesting its cause was the emission of an A-wave in the future from an electron in the ceiling of the office. But what then caused the emission of that A-wave in the future?

This is what I was (fuzzily) saying about CTI moving the question to the back-burner and not addressing it head on. It has out-sourced the indetermism in the present to indeterministic events in the future. I then sneared at it as argumentum ad mysterium

https://en.wikipedia.org/wiki/Measurement_problem
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on November 23rd, 2019, 9:28 pm 

hyksos » November 23rd, 2019, 5:19 pm wrote:
My understanding of CTI is that particles in our local surroundings can interact non-locally in a wavelike manner with particles at remote distances

That is not CTI. You just described regular entanglement.


CTI is regular entanglement expressed in Cramer's way which is a bit more visual and teleological than the usual. Other than that, what is the difference?

hyksos » November 23rd, 2019, 5:19 pm wrote:
This means that interacting particles are in direct quantum contact despite their observational separation so that, at the quantum level, there is no such thing as distance.

That doesn't follow from CTI at all. I have never in my life seen "Direct quantum contact" mentioned in any article on Interpretations of QM in my entire life. The only place I've ever seen that phrase used is in Faradave's posts on this forum.

Cramer’s quantum handshake completing a transaction is just another way of saying direct quantum contact, non-local interaction, entanglement, quantum superposition or other phrases for the same type of phenomenon.

If you want to be picky about semantics, the acronym for John Cramer’s Transactional Interpretation of Quantum Mechanics is TIQM. I have never in my life seen "TIQM" mentioned in any article on Interpretations of QM as “CTI” in my entire life. The only place I've ever seen that phrase used is in your posts on this forum.

hyksos » November 23rd, 2019, 5:19 pm wrote:Your description of "no space" can be demonstrated false in simple lab experiment.

Bell and Aspect in the early sixties were the first to demonstrate non-local “no space” interaction in the laboratory and it has repeatedly been demonstrated ever since.
hyksos » November 23rd, 2019, 5:19 pm wrote:The question was posed in the narrative about the physics professor at Princeton in his office. A photon at a shallow angle to the glass window can reflect or transmit at a 50/50 chance. What in the universe causes the decision?


The primary cause for this 50/ 50 decision going one way or the other is the distance to the backside of the glass and wavelength of the light. Feynman has a detailed explanation of this in his QED and the Wheeler-Feynman Absorber Theory has an explanation that is no different from Cramer’s except that Cramer explains this as a wave phenomenon rather than with photon particles moving forward and backwards in time. Cramer's TIQM is essentially the old W-F Absorber theory with waves instead of particles preceding an EM interaction and the change over is an enormous improvement over Wheeler and Feynman.
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Re: Cramer's Transactional Interpretation.

Postby hyksos on November 26th, 2019, 8:08 am 

CTI is regular entanglement expressed in Cramer's way which is a bit more visual and teleological than the usual. Other than that, what is the difference?

CTI (pardon me, TIQM) has an A-wave, which is something you are avoiding talking about.

Bell and Aspect in the early sixties were the first to demonstrate non-local “no space” interaction in the laboratory and it has repeatedly been demonstrated ever since.

Yes there are dozens upon dozens of physical phenomena observed in labs that must be explained as non-local interactions. I'm not denying any of those. But this non-locality is destroyed upon measurement--- giving rise to something called the MEASUREMENT PROBLEM. I claimed explicitly in my post that this is what TIQM is trying to resolve. You skipped over that primary claim in my post, entirely.

https://plato.stanford.edu/entries/qt-issues/#MeasProb

https://en.wikipedia.org/wiki/Measurement_problem

http://www.pitt.edu/~jdnorton/teaching/ ... asurement/

https://www.britannica.com/topic/philos ... nt-problem


The primary cause for this 50/ 50 decision going one way or the other is the distance to the backside of the glass and wavelength of the light. Feynman has a detailed explanation of this in his QED

This is factually false. There is nothing in QED that resolves the measurement problem.

Yes QED contains a detailed explanation for why this shallow-angle probability is 50/50. But it pointedly and explicitly does NOT EXPLAIN why a particular outcome is observed.

The book QED is a "gentle introduction to field theory" for the layperson. You may have noticed that it contains zero equations. Like, zero. It is not a textbook.

To explain why a particular outcome is observed and not the other, we have to address the Measurement Problem. It my strong and bald claim: Cramer, in positing TIQM was primarily concerned with the Measurement Problem. If you respond to this post and you do not address that claim, then you and I are not having a "conversation".

Cramer's TIQM is essentially the old W-F Absorber theory with waves instead of particles preceding an EM interaction and the change over is an enormous improvement over Wheeler and Feynman.

It's not an improvement. I already typed up a bullet point list showing why it's not.
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on November 27th, 2019, 2:23 am 

hyksos » November 26th, 2019, 7:08 am wrote: But this non-locality is destroyed upon measurement--- giving rise to something called the MEASUREMENT PROBLEM. I claimed explicitly in my post that this is what TIQM is trying to resolve. You skipped over that primary claim in my post, entirely.

In TICM, the non-local events preceding our observation of light are time symmetric or atemporal and take place outside spacetime and are therefore not observable. Cramer’s retarded waves moving backward in time are nullified by his advance waves moving forward in time leaving behind a completed transaction that an observer interprets as a single photon exchange of energy traveling from a signal source to a receiver.

The observation of an energy exchange takes place AFTER the the non-local events are complete so measurement does not destroy non-locality. This is probably why Cramer has little or nothing to say about the measurement problem.

hyksos » November 26th, 2019, 7:08 am wrote:
The primary cause for this 50/ 50 decision going one way or the other is the distance to the backside of the glass and wavelength of the light. Feynman has a detailed explanation of this in his QED

This is factually false. There is nothing in QED that resolves the measurement problem.

Yes QED contains a detailed explanation for why this shallow-angle probability is 50/50. But it pointedly and explicitly does NOT EXPLAIN why a particular outcome is observed.

The chance of light entering or being reflected by a glass surface is not 50/50 but it ranges from nearly 0 to 100 percent and it is predictable given just the wavelength of the light and depth of the glass and Feynman explained why in simple terms in QED.

In QED Feynman’s field of photons moving backwards in time is absorbed into his field of photons moving forward in time leaving a single photon path that can be detected AFTER the non-local events have transpired so, in this case also, detection does not destroy non-locality so there is no measurement problem here either. The measurement problem is addressed in other theories where the question arises as to whether or not local “reality” can exist without observation.
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Re: Cramer's Transactional Interpretation.

Postby hyksos on November 29th, 2019, 4:35 pm 

In TICM, the non-local events preceding our observation of light are time symmetric or atemporal and take place outside spacetime and are therefore not observable. Cramer’s retarded waves moving backward in time are nullified by his advance waves moving forward in time leaving behind a completed transaction that an observer interprets as a single photon exchange of energy traveling from a signal source to a receiver.


"time symmetric or atemporal and take place outside spacetime and are therefore not observable."
(* citation needed)

The observation of an energy exchange takes place AFTER the the non-local events are complete so measurement does not destroy non-locality. This is probably why Cramer has little or nothing to say about the measurement problem.

Once again, I assert in plain text : Cramer's entire motivation for TIQM was to address the measurement problem.

There are many interps of QM out there of different flavors. They each have a different motivation, and sometimes their motivations overlap. For example, DeBroglie-Bohm Guiding Wave was an attempt to bring trajectories back into QM.

Cramer's TIQM has a specific ontological commitment, namely that a photon's decision to reflect or transmit is not an acausal event... (what Einstein called "God throwing dice.") but is in fact totally determined by an Advanced Wave emitted from the absorber in the future. Therefore I assert ---> TIQM is an attempt to address the Measurement Problem.

The chance of light entering or being reflected by a glass surface is not 50/50 but it ranges from nearly 0 to 100 percent and it is predictable given just the wavelength of the light and depth of the glass and Feynman explained why in simple terms in QED.

You already said this, and I already addressed it. Now you are saying it again and we are going in circles. This statement is not just "wrong" , it exhibits a profound lack of understanding of even the context of what you are reading. My job on this forum is not to give you a free education in modern physics, and so every minute I waste in my life correcting you is making me increasingly frustrated.

But let's try this.

+ QED is a wonderful book that. everyone should have it on their shelf {heap additional praise and other info about why it was written and Feynman as a science teacher blah blah blah}.

+ It's fun and other should have fun with it. I read it when I was 17.

+ QED is not NOT NOT Feynman's interpretation of Quantum Mechanics.

+ QED is NOT a textbook. It is a "gentle introduction" to Quantum Field theory of the electromagnetic force, written and targeted at a lay audience. It has no equations in it. Look at your copy of it. Zero equations. When Feynman says we "add all the arrows together" he is actually referring to a path integral. But laypersons have not sat in upper level university courses on Lagrangian mechanics and the calculus of variations : so he writes "add all the arrows". Get it?

https://en.wikipedia.org/wiki/Path_integral_formulation

https://en.wikipedia.org/wiki/Lagrangian_mechanics

https://en.wikipedia.org/wiki/Calculus_of_variations



+ QED explains how the 50/50 probability of the photon is calculated simple terms. Yes.

+ QED most assuredly DOES NOT tell you what causal mechanism determines how a photon behaves upon measurement. If Feynman spent a single sentence describing what CAUSES that decision, he would have been writing an interpretations of QM. But QED is not not NOT NOT an interpretation of QM.

This non-locality that you keep blabbering about is a feature of the orthodox 1939 version of QM and most of us called it "entanglement".

1.) Entanglement is not guaranteed to happen,

2.) Entanglement does not always happen maximally,

3.) Human observers can destroy non-local entanglement anytime we want by measuring a system explicitly.

4.) We have no quantum computers in our living rooms. Why? Because a noisy warm environment can destroy the fragile non-local interactions of qubits. This is not a every-once-in-a-while thing. Decoherence is the bane of all quantum computers. Even the ones they build in cryogenic labs.

These 4 items are perfectly described and explicitly predicted by the formalism. They derive from the fact that the (states of a) Schroedinger wave is expressed in a Hilbert space, and that these things called observables will either commute or not commute in that space. When two observables are totally orthogonal you get so-called "maximal" entanglement. YOu can also have "weakly" entangled systems. Long-story short : we don't need a theory of entanglement from you nor Faradave. We already have a theory.

There is unitary evolution where long-separated pieces of the same wave function affect each other across large distances. Then there is this thing variously called decoherence, or the "Collapse of the wave function" where these formally entangled pieces of a wave function become distinct, deterministic and local particles.

Why does this occur? Does it occur at all? <----- This is the Measurement Problem.

We don't have access to Richard Feynman on this forum. But very much in the manner of Susskind, I woudl presume that Feynman was averse to interps-of-QM. One of those guys who would probably say "We don't need them". This idea that we don't need interps-of-QM at all in the first place : this ideas is a sentiment that is widely shared by many people today. I'm sorry that this forum does not have any such people to come here and chime in.

Feynman had become very comfortable -- philosophically and intellectually comfortable -- in living in a universe where totally non-determined physical events happen. He was comfortable with non-local entanglement happening. He no longer felt any inner emotional need to probe deeper and find some completely deterministic mechanism "underlying" the large-scale features of the theory.

John Cramer is different. He is one of those guys feeling something is missing from the picture. He added these Advanced Waves to the formalism , which are not in the formalism. At the very least, we know he added these backwards-in-time A-waves in order to help undergrads visualize quantum processes.
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on November 30th, 2019, 2:07 am 

hyksos » November 29th, 2019, 3:35 pm wrote:
"time symmetric or atemporal and take place outside spacetime and are therefore not observable."
(* citation needed)

http://www-users.york.ac.uk/~mijp1/tran ... TI_30.html
"3.7 Collapse and Nonlocality in the Transactional Interpretation
In the TI the collapse of the state vector is interpreted as the completion of the transaction started by the OW and the CW exchanged between emitter and absorber. The emergence of the transaction from the SV does not occur at some particular location in space or at some particular instant of time, but rather forms along the entire four-vector which connects the emission locus with the absorption locus (or loci in the case of multiple correlated particles). The transaction employs both retarded and advanced waves which propagate, respectively, along positive and negative lightlike (or timelike) four-vectors. Since the sum of these four-vectors can span spacelike and negative timelike or lightlike intervals, the "influence" of the transaction in enforcing the correlations of the quantum event is explicitly both nonlocal and atemporal."

OW is an offer wave, CW is a confirmation wave. These are the advanced and retarded waves of the W-F Absorber theory. SV is the state vector of a quantum particle. It is the position, momentum, time, energy, spin and isospin and other variables that give a quantum particle its identity.[/i]

hyksos » November 29th, 2019, 3:35 pm wrote:
Once again, I assert in plain text : Cramer's entire motivation for TIQM was to address the measurement problem.

Cramer's TIQM has a specific ontological commitment, namely that a photon's decision to reflect or transmit is not an acausal event... (what Einstein called "God throwing dice.") but is in fact totally determined by an Advanced Wave emitted from the absorber in the future. Therefore I assert ---> TIQM is an attempt to address the Measurement Problem.


Assertions are meaningless without support. You may be entirely right so go ahead and explain why.

hyksos » November 29th, 2019, 3:35 pm wrote:
+ QED explains how the 50/50 probability of the photon is calculated simple terms. Yes.


Are you saying the calculated probability is 50/50 and not 0 to 100?
That is the one part I don't understand because the probability is rarely 50/50.

hyksos » November 29th, 2019, 3:35 pm wrote:
3.) Human observers can destroy non-local entanglement anytime we want by measuring a system explicitly.


The question remains as to whether entanglement was lost before the observation or if the measurement caused entanglement to be lost. The latter posibility is the measurement problem.

hyksos » November 29th, 2019, 3:35 pm wrote:
There is unitary evolution where long-separated pieces of the same wave function affect each other across large distances. Then there is this thing variously called decoherence, or the "Collapse of the wave function" where these formally entangled pieces of a wave function become distinct, deterministic and local particles.

Why does this occur? Does it occur at all? <----- This is the Measurement Problem.


We know entanglement and and decoherence occur. If they happen spontaneously without observation, then there is no Measurement Problem. If measurement is the cause of decoherence, then we have a measurement problem with the question of whether or not our awareness (consciousness) is an active participant in the nature of what we call reality. That is how I see the measurement problem.

hyksos » November 29th, 2019, 3:35 pm wrote:
Feynman had become very comfortable -- philosophically and intellectually comfortable -- in living in a universe where totally non-determined physical events happen. He was comfortable with non-local entanglement happening. He no longer felt any inner emotional need to probe deeper and find some completely deterministic mechanism "underlying" the large-scale features of the theory.

John Cramer is different. He is one of those guys feeling something is missing from the picture. He added these Advanced Waves to the formalism , which are not in the formalism. At the very least, we know he added these backwards-in-time A-waves in order to help undergrads visualize quantum processes.


The Wheeler-Feynman Absorber theory and QED both include forward and retarded signaling the same as Cramer’s TIQM.

http://www-users.york.ac.uk/~mijp1/tran ... TI_30.html

"3.1 Advanced Waves and Wheeler-Feynman Absorber Theory
The basic element of the transactional interpretation is an emitter-absorber transaction through the exchange of advanced and retarded waves, as first described by Wheeler and Feynman (1945, 1949) [see also (Feynman, 1967b)]. Advanced waves are solutions of the electromagnetic wave equation and other similar wave equations which contain only the second time derivative. Advanced waves have characteristic eigenvalues of negative energy and frequency, and they propagate in the negative time direction."
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Re: Cramer's Transactional Interpretation.

Postby hyksos on April 21st, 2020, 2:27 am 

bangstrom » November 30th, 2019, 10:07 am wrote:http://www-users.york.ac.uk/~mijp1/tran ... TI_30.html
"3.7 Collapse and Nonlocality in the Transactional Interpretation
In the TI the collapse of the state vector is interpreted as the completion of th

And nothing you have cited there implies or suggests something "outside of spacetime".



The Wheeler-Feynman Absorber theory and QED both include forward and retarded signaling the same as Cramer’s TIQM.

http://www-users.york.ac.uk/~mijp1/tran ... TI_30.html

"3.1 Advanced Waves and Wheeler-Feynman Absorber Theory
The basic element of the transactional interpretation is an emitter-absorber transaction through the exchange of advanced and retarded waves,

Again, absolutelyt none of the material you have linked supports or implies that Feynman was engaging with Advanced Waves moving backwards in time in at attempt to address the measurement problem.

The website you linked explicitly states that they Feynman messed around with these ideas for a few years in order to address the problem of electron self-interactions. THe website further states that he abandoned the idea, and why he abandoned it. Nice try though.
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on April 21st, 2020, 4:36 am 

hyksos » April 21st, 2020, 1:27 am wrote:
bangstrom » November 30th, 2019, 10:07 am wrote:http://www-users.york.ac.uk/~mijp1/tran ... TI_30.html
"3.7 Collapse and Nonlocality in the Transactional Interpretation
In the TI the collapse of the state vector is interpreted as the completion of th

And nothing you have cited there implies or suggests something "outside of spacetime".

If waves moving both forward and backward in time are not outside spacetime, then I don’t know where spacetime is.

hyksos » April 21st, 2020, 1:27 am wrote:Again, absolutelyt none of the material you have linked supports or implies that Feynman was engaging with Advanced Waves moving backwards in time in at attempt to address the measurement problem.

The website you linked explicitly states that they Feynman messed around with these ideas for a few years in order to address the problem of electron self-interactions. THe website further states that he abandoned the idea, and why he abandoned it. Nice try though.

Perhaps I don’t understand your view of the “measurement” problem but Wheeler and Feynman certainly did employ advanced and retarded waves moving both forward and backward in time as part of their Absorber Theory for light.

Einstein attended one of their early lectures on the topic and informed Wheeler and Feynman of a remarkably similar time symmetric theory proposed much earlier by Hugo Tetrode.
Einstein- and I think it was Bohr- once visited Tetrode to discuss his theory but they were turned away by his housekeeper because Tetrode was too sick to entertain visitors. He died of TB not long afterward and nothing remains of his theory beyond what he published in Zeitschrift fur Physik.

Feynman later abandoned the absorber theory. I don’t know why but suspect it was because of the absurdity of his “magic” photons flying everywhere taking all possible paths and traveling at every possible speed including all speeds in reverse.

The simpler part of the W-F theory with waves moving forward and backward in time (without the magic photons) as proposed by Tetrode was more recently taken up by Pope and Osborne in their Angular Momentum Synthesis POAMS and also by Milo Wolff in his Wave Structure of Matter theory WSM.

The old W-F Absorber theory was recently adopted- minus the magic photons- by John Cramer in his TIQM. Cramer is now retired and the main keeper of his theory is Ruth Kastner who has added a modification of her own so the time symmetric theory with waves moving both forward and backward in time is still very much alive.
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Re: Cramer's Transactional Interpretation.

Postby Positor on April 21st, 2020, 10:27 am 

Can someone please explain to me, as a layman, what it means for a wave to travel "backward in time"? If t2 is a later time than t1, in what sense does the wave reach t1 'after' it reaches t2?

How would this be represented on a Minkowski diagram?
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Re: Cramer's Transactional Interpretation.

Postby hyksos on April 21st, 2020, 12:48 pm 

Perhaps I don’t understand your view of the “measurement” problem but Wheeler and Feynman certainly did employ advanced and retarded waves moving both forward and backward in time as part of their Absorber Theory for light.

The website you linked does not say this -- at all. Feynman noodled around with it because of theoretical problems of the electron self-interaction. Anyone can click the link you provided and confirm.


Feynman later abandoned the absorber theory. I don’t know why but suspect it was

WHat do you mean that you "yont know why" ? The website explains why he abandoned it.
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Re: Cramer's Transactional Interpretation.

Postby Faradave on April 21st, 2020, 3:33 pm 

Positor » April 21st, 2020, 10:27 am wrote:Can someone please explain to me, as a layman, what it means for a wave to travel "backward in time"? If t2 is a later time than t1, in what sense does the wave reach t1 'after' it reaches t2?

How would this be represented on a Minkowski diagram?

Like Minkowski diagrams, Feynman diagrams typically have a vertical time coordinate and a horizontal space coordinate (representing the direction of motion). Speed limit c is represented with a slope of +1 (45° from vertical).* Anything traveling backward in time would make a greater angle than that.

The biggest difference between Minkowski's diagrams and Feynman's is scale. The former are typically cosmic and the latter quantum. A caveat is that like Las Vegas, what happens in a Feynman diagram stays in a Feynman diagram. That is, our observations in the macro world can only detect those "real" particles and energies which emerge from the bounds of a Feynman diagram. The processes within are considered "virtual" since they occur at a scale under the veil of uncertainty. This gives scientists great liberty in imagining what those processes might be, including faster than light phenomena, which cannot be disproved. The only criterion is that the predicted outcomes of these processes match observation. They do this exceedingly well!

A real particle interaction is considered the consolidation (or "integration") of many systematically imagined virtual interactions (each with its own Feynman diagram). But no one of these is completely real but itself. Thus, they can exhibit lots of rule breaking, so long as a meaningful majority of them consolidate to a real result.

*Actually, with time on the vertical, slope is Δt/Δx the inverse of speed but assigned a convenient value of 1, limit c looks the same either way. The coordinates may be rotated as convenient, so long as they are clearly labled.

So in a given Feynman diagram, not just waves but particles can appear to travel backward in time. Here's how an electron-positron annihilation is drawn.
Image
Note that the virtual particle (horizontal red line) appears instantaneous and the positron's arrow is pointing backward in time. Wheeler and Feynman both suggested that a positron is like an electron traveling backward in time. What that means is that the combined properties of intrinsic spin and electric charge of an electron, if reversed in time would be identical those of a positron moving forward in time.
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on April 21st, 2020, 5:50 pm 

hyksos » April 21st, 2020, 11:48 am wrote:
The website you linked does not say this -- at all. Feynman noodled around with it because of theoretical problems of the electron self-interaction. Anyone can click the link you provided and confirm.

What is your “it”? I am guessing “it” is waves moving forward and backward in time in electron self- interaction. This was the central part of Feynman’s Absorber theory.

hyksos » April 21st, 2020, 11:48 am wrote:
Feynman later abandoned the absorber theory. I don’t know why but suspect it was

WHat do you mean that you "yont know why" ? The website explains why he abandoned it.

If you know why he abandoned the Absorber theory, why not tell me what I missed?
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on April 21st, 2020, 6:46 pm 

Positor » April 21st, 2020, 9:27 am wrote:Can someone please explain to me, as a layman, what it means for a wave to travel "backward in time"? If t2 is a later time than t1, in what sense does the wave reach t1 'after' it reaches t2?

Yes, what Faradave said.

If two remote particles are able to act in unison as if they are side by side sharing a common wavefunction, this is only possible if the wave connecting them is moving both forward and backward in time. This condition is what we call entanglement. It means that events at t1 and t2 are simultaneous so there is no such thing as before or after from the perspective of the particles. Both events are happening at the same time on both ends.

Outside observers will see the same events as before and after depending upon which event is the closest so these observations are observer-dependent.

Making sense of this requires a non-Newtonian understanding of time such as Block time.

Positor » April 21st, 2020, 9:27 am wrote:How would this be represented on a Minkowski diagram?

On the Minkowski diagram, this means that any charged particle can interact instantly and directly with any other charged particle on the same light cone but our observation of the separate events is limited to the long route through the dimension of Minkowski spacetime.

From the dimension of light, emission and absorption are simultaneous events, but from our dimension of Minkowski spacetime, we see the emission and absorption of light as always including a c related ratio of distance and time.
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Re: Cramer's Transactional Interpretation.

Postby Positor on April 21st, 2020, 10:20 pm 

Faradave and bangstrom,

Thanks for the replies.
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Re: Cramer's Transactional Interpretation.

Postby hyksos on April 30th, 2020, 4:28 pm 

bangstrom » April 22nd, 2020, 1:50 am wrote:If you know why he abandoned the Absorber theory, why not tell me what I missed?

This is literally copy-pasted from the article that you linked.

Regrettably, the WF paper, while mathematically correct, proved be an invalid way of dealing with self-energy. When the offending assumption of non-interaction is removed from the WF formalism, what remains is a classical self-consistent and time-symmetric electrodynamics which cannot be used to deal with the problem of self energy.

This is pretty much what I said to you earlier. Feynman approached the paper as a way of dealing with a particular problem with electron self-interaction. Then he later abandoned the approach when it became evident that the WF paper only applies after having removed self-interactions of the electron.

Again from the very article you linked,
Further, this WF formalism is not particularly useful as an alternative method of calculating the electrodynamics of radiative processes because the mathematical description of radiation explicitly involves the interaction of the emitter with the entire future universe.

"the interaction of the emitter with the entire future universe". This sentiment re-iterates what I already posted earlier in this thread about CTI.

Here :


3.
CTI might be argumentum ad mysterium. It might be approaching the measurement problem and not addressing it head on. I worry (this is my opinion of course) that CTI is moving the measurement problem to a backburner. While we seem to have found a source of determinism for a present spacetime event, the mystery is "outsourced" to a fuzzy future state which is seductively mysterious enough to be believably undetermined.



and again, here :

This is what I was (fuzzily) saying about CTI moving the question to the back-burner and not addressing it head on. It has out-sourced the indetermism in the present to indeterministic events in the future. I then sneared at it as argumentum ad mysterium

I am happy to see that the articles you link agree with things I already concluded on my own. Both of these paragraphs have been in this thread for weeks. I guess nobody wants to respond to them (?)
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Re: Cramer's Transactional Interpretation.

Postby bangstrom on April 30th, 2020, 7:42 pm 

hyksos » April 30th, 2020, 3:28 pm wrote:
bangstrom » April 22nd, 2020, 1:50 am wrote:If you know why he abandoned the Absorber theory, why not tell me what I missed?

This is literally copy-pasted from the article that you linked.


Yes, Feynman abandoned his Absorber Theory but I don’t know why. I linked to an article critical of Feynman’s theory but it was not written by Feynman nor does it say why he abandoned it. I can guess why but I don't find that information in the quote.
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Re: Cramer's Transactional Interpretation.

Postby hyksos on April 30th, 2020, 10:23 pm 

It says WF is mathematically correct. But it is useless for calculations of radiative processes. Academics sometimes have different motivations and goals in their lives than do people on a forum like this. They need to publish. They want a in-road to a prettier/faster way to express something as an equation. The WF paper didn't provide this, because it gave a formulation of the emitter interacting with the entire future universe.
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