Questions re Cramer's Transactional Interpretation?

[RUTA]

... there are still advanced waves involved in the atypical transaction; and it is their overlap with their out-of-phase reflected retarded component that builds up the field to full retarded strength and defines a quantum being emitted from the emitter and continuing on to the infinite future without being absorbed.

This explains my confusion -- I didn't know you could have CWs connecting x to infinity. Thus, there is no problem posed by the fact that the current reigning cosmology model (LambdaCDM) permits emission to infinity. This is very different than direct particle interaction (obviously), and I didn't realize you had made this change.

I don't have any other questions for you now ... maybe I'll generate more for your presentation in Miami next month. Have a safe trip down!

 

[rkastner]

If you look at Cramer 1983, he explains how the 'absorberless' transaction works. It all looks physically consistent to me. The reflected advanced wave from the emitter continues on to t=infinity in an open universe. We do have to keep in mind, however, that the 'current reigning cosmology' is not incontrovertible fact and should not be taken as ruling out any given interpretation even if the latter does not seem obviously harmonious with it. We are continually learning new things in cosmology and who knows how that will ultimately turn out...

 

[RUTA]

We do have to keep in mind, however, that the 'current reigning cosmology' is not incontrovertible fact and should not be taken as ruling out any given interpretation even if the latter does not seem obviously harmonious with it. We are continually learning new things in cosmology and who knows how that will ultimately turn out...

If a strong interpretation of QM is incompatible with the reigning cosmology model, I would say cosmology is probably wrong. That's actually how I expected you to respond

 

[rkastner]

As I explained , however, the interpretation (PTI) is *not * incompatible. But thanks for characterizing it as a strong interpretation.

 

[RUTA]

As I explained , however, the interpretation (PTI) is *not * incompatible.

To my surprise.

But thanks for characterizing it as a strong interpretation.

You're welcome.

 

[HelpNowPlease]

If yes, then why there is an appearance of the wave function collapse?

There is only something to collapse, if it has something to deflate in the first place.

Maybe the real question is, whether the wave function is objective or subjective. In other words, it is merely a field which is there for us to keep track of our calculations? Early quantum field theorists thought exactly that. But of course, we can't truly believe this today. What we might really believe is there is a battle to prove maybe the wave function is physical and tangible, not some ethereal field of probabilities.

 

[HelpNowPlease]

There is already evidence pointing to the physical interpretation of the wave function.

 

[Maui]

The biggest objection to a probability wave being real seems to be that the majority can not believe it(that the world is like that based on their personal preferences, despite all the evidence to the contrary).

 

[rkastner]

There is a recent proof by Pusey et al that the wave function cannot be considered merely as a statistical quantity describing our incomplete knowledge of quantum entities with real (but unknown) properties. See: http://arxiv.org/abs/1111.3328.

There was also a reply on the arxiv pointing out that the Pusey et al proof depends on realism about quantum objects (i.e., that they do have real but unknown properties). I do not recall the author(s) of that paper, but it argues that the proof does not rule out instrumentalist views of the wave function (or quantum state). As is probably evident from my work, I think that the quantum state does indeed refer to a real entity and that's what explains the predictive power of quantum theory. I am almost finished writing a book on my 'possibilist' variation of TI (PTI) and I hope you'll stay tuned for that. These possibilities may seem 'ethereal' compared to concrete events, but they are crucially important for the inception of a concrete event. I invite anyone interested to drop into my blog, rekastner.wordpress.com. Happy New Year, everyone!

 

[bohm2]

There is a recent proof by Pusey et al that the wave function cannot be considered merely as a statistical quantity describing our incomplete knowledge of quantum entities with real (but unknown) properties. See: http://arxiv.org/abs/1111.3328.

There was also a reply on the arxiv pointing out that the Pusey et al proof depends on realism about quantum objects (i.e., that they do have real but unknown properties). I do not recall the author(s) of that paper, but it argues that the proof does not rule out instrumentalist views of the wave function (or quantum state).

I didn't think the PBR theorem (or any theorem) can rule out the instrumentalist view. Leifer argues that such views are next to impossible to rule out:

I would classify the Copenhagen interpretation, as represented by Niels Bohr, under option 2 (e.g. Wavefunctions are epistemic, but there is no deeper underlying reality). One of his famous quotes is:

There is no quantum world. There is only an abstract physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature…[4]​

and “what we can say” certainly seems to imply that we are talking about our knowledge of reality rather than reality itself. Various contemporary neo-Copenhagen approaches also fall under this option, e.g. the Quantum Bayesianism of Carlton Caves, Chris Fuchs and Ruediger Schack; Anton Zeilinger’s idea that quantum physics is only about information; and the view presently advocated by the philosopher Jeff Bub. These views are safe from refutation by the PBR theorem, although one may debate whether they are desirable on other grounds, e.g. the accusation of instrumentalism.

Can the quantum state be interpreted statistically?
http://mattleifer.info/2011/11/20/can-the-quantum-state-be-interpreted-statistically/

Not that I buy this author's arguments but maybe you mean this paper?

Pusey, Barrett and Rudolph claim to prove that statistical interpretations of quantum mechanics do not work. In fact, their proof assumes that all statistical interpretations must be based on hidden variable realism. Effectively, the authors demand from the start that reality must be decided by mathematics, and not by measurements. If this unjustified assumption is dropped, the quantum formalism has a natural statistical interpretation that fully explains the paradox presented by the authors.

The quantum state should be interpreted statistically
http://lanl.arxiv.org/PS_cache/arxiv/pdf/1112/1112.2446v1.pdf

 

[rkastner]

Yes, thanks, that's the paper I was thinking of. I agree that pure instrumentalist views are hard to rule out via the kind of proof presented by Pusey et al.

 

[rkastner]

Update: My book on the possibilist approach to TI and its relativistic extension is forthcoming this fall, http://www.cambridge.org/us/knowledge/isbn/item6860644/?site_locale=en_US

Also I uploaded the audio and ppt from my recent talk on how TI solves the measurement problem, here: http://transactionalinterpretation.org

 

[bohm2]

This is an interesting paper/EPR experiment that seems compatible with the Transactional Interpretation. Then again, I might be misunderstanding it?

The only reasonable resolution seems to be that of the Two-State-Vector Formalism, namely that the weak measurement's outcomes anticipate the experimenter’s future choice, even before the experimenter themselves knows what their choice is going to be. Causal loops are avoided by this anticipation remaining encrypted until the final outcomes enable to decipher it...Ergo, the weak measurements’ agreement with the strong measurements could have been obtained only by the former anticipating the spin orientation to be chosen for the latter. This result indicates the existence of a hidden variable of a very subtle type, namely the future state-vector...Therefore, when a weak measurement precedes a strong one, the only possible direction for the causal effect is from future to past.

The authors also suggest support for free will but I don't understand their argument:

Finally, this experiment sheds a new light on the age-old question of free will. Apparently, a measurement's anticipation of a human choice made much later renders the choice fully deterministic, bound by earlier causes. One profound result, however, shows that this is not the case. The choice anticipated by the weak outcomes can become known only after that choice is actually made. This inaccessibility, which prevents all causal paradoxes like “killing one's grandfather,” secures human choice full freedom from both past and future constraints.

Can a Future Choice Affect a Past Measurement's Outcome?
http://arxiv.org/ftp/arxiv/papers/1206/1206.6224.pdf

 

[audioloop]

I would classify the Copenhagen interpretation, as represented by Niels Bohr, under option 2 (e.g. Wavefunctions are epistemic, but there is no deeper underlying reality). One of his famous quotes is:
There is no quantum world. There is only an abstract physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature…[4]
and “what we can say” certainly seems to imply that we are talking about our knowledge of reality rather than reality itself. Various contemporary neo-Copenhagen approaches also fall under this option, e.g. the Quantum Bayesianism of Carlton Caves, Chris Fuchs and Ruediger Schack; Anton Zeilinger’s idea that quantum physics is only about information; and the view presently advocated by the philosopher Jeff Bub. These views are safe from refutation by the PBR theorem, although one may debate whether they are desirable on other grounds, e.g. the accusation of instrumentalism.

leifer say that, but...

Fuchs say

...The quantum system represents something real and independent of us; the quantum state represents a collection of subjective degrees of belief about something to do with that system (even if only in connection with our experimental kicks to it). The structure called quantum mechanics is about the interplay of these two things—the subjective and the objective.Chris Timpson

Realists about quantum mechanics may also want to be realists about the quantum state. But what does that mean? If one wants to think of the quantum state as representing a kind of thing, there is the question of what kind of thing that would be.----
...then, how many types of realism ?
quantum state realists, quantum system realists and quantum mechanics realists and various combinations between them...

 

[rkastner]

I provide an answer to the above question --

("...realists about the quantum state. But what does that mean? If one wants to think of the quantum state as representing a kind of thing, there is the question of what kind of thing that would be.")

-- in my new book, which you can get for a 20% discount here:

http://www.cambridge.org/us/knowledge/discountpromotion/?site_locale=en_US&code=L2TIQM

Also see my website, transactionalinterpretation.org, for introductory and preview material.