Can I take the transactional interpretation seriously?

[gentzen]

My first "active" encounter with the transactional interpretation happened when I tried to react to Ruth Kastner's criticism of consistent histories. My next encounter happened when I was fighting with reciprocity occuring for crystal effects in electron scattering, and hoped for help from time symmetric interpretations. Naturally, I started studying TI by studying John Cramer's initial version, and was seriously underwhelmed. Roderich Tumulka in his book "Foundations of Quantum Mechanics" provides a good explanation for why this happend. He discusses TI in the section on the Copenhagen Interpretation, with reference to what he wrote in the subsection "Narratives, But No Serious Ones":

When calculating predictions that can be compared to experimental data, adherents of CI often tell a story about the physical meaning of the mathematical elements of the calculation. ... But this story is not intended to describe what actually happens. On the contrary, CI insists that such narratives should not be taken seriously. They are just metaphor, or allegory, or analogy; they just serve as a mnemonic for the calculation, as a help for remembering the correct formulas or for setting up the corresponding formulas in similar calculations.

He frames his explanation by writing: "In 2005, I met John Cramer at a conference in Sydney, and since we had both arrived a day early, we spent a pleasant afternoon at the zoo chatting about, among other things, the foundations of quantum mechanics. Let me describe my take on his view."

That is, with the “transactional interpretation,” he did not intend to replace orthodox quantum mechanics with something else, he wanted to flesh it out further, and he wanted to provide further ones of these stories that help you remember the formulas and that attach some picture to each symbol in the calculation. ... If you read Cramer’s paper expecting a fundamental physical theory, i.e., a hypothesis about what happens in nature comparable to Bohmian mechanics, GRW, and many-worlds, then you will find a mess. It will remain unclear, for example, what the ontology is, what the unexplained notion of “transaction” means in terms of the ontology, or how those of his stories should be understood that involve several rounds of revision of space-time histories (...). But if the stories serve more as a visualization of the formulas, then they do not have to provide an unambiguous, coherent picture of events.

I highlighted his description of how interactions like mine with Cramer's TI will likely play out.

However, I still have no idea whether interactions with Ruth Kastner's version of TI will play out similarly, or not. Can TI be a serious interpretation at all? But assuming Ruth Kastner's version would not exist, how could one describe TI? Perhaps as "an inconsistent interpretation"? Or as "a narrative", like Tumulka suggested? Can it make sense to take a mere narrative seriously? (The narrative told by Feynman diagrams suggests itself, which also attaches "some picture to each symbol in the calculation".)

 

[Ken G]

I think the deeper question to ask is if anyone should ever take any interpretations of a physics theory "seriously." Personally, I think that's a wrong purpose to attach to any interpretation, but it depends on what you mean by "serious." If all you mean is "useful" or "valuable," then sure, you can take any interpretation seriously if it helps you make correct predictions, or helps you organize your thinking in some way. But if you mean "describes what is really happening" in some sort of unique or absolute way, I would simply point to the history of our entire endeavor to critique that attitude. It generally leads to the unscientific perspective that "we were all confused in the past but now we have it," an attitude we see throughout history and one that is no doubt just as wrong today as it has always been.

 

[PeterDonis]

@gentzen only you can answer the title question. No one else can answer it for you.

 

[gentzen]

@gentzen only you can answer the title question. No one else can answer it for you.

but it depends on what you mean by "serious." If all you mean is "useful" or "valuable," then sure, you can take any interpretation seriously if it helps you make correct predictions, or helps you organize your thinking in some way.

The primary meaning of "take seriously" I had in mind was whether John Cramer tried to communicate something that he personally felt correct and important, or whether he acted just like an overwhelmed student or LLM trying to give the impression that his explanations make sense. (Maybe he accepts that he is overwhelmed, and wants to be heared and noticed nevertheless.)

What he told Tumulka clarifies that he never believed that his narrative was consistent. But maybe he still believed that the retrocausality occuring in that narrative was important and correct. Tim Maudlin discussed his interpretation because of that retrocausality, and Ruth Kastner later joined that discussion for the same reason. The result of that interaction was summarized by Sabine Hossenfelder as follows:

Indeed, that retrocausality could explain the seemingly strange features of quantum mechanics was proposed by John Cramer in the 1980s. It’s called the Transactional Interpretation. It was further developed by Ruth Kastner but Cramer seems to not be particularly enchanted by Kastner’s version. In a 2015 paper he called it “not incorrect, but we consider it to be unnecessarily abstract.” That’s academia. Nothing quite like being dissed in the 1st person plural.

For me, this is the point at which I can no longer take John Cramer seriously. But I am German, just like Sabine Hossenfelder. Ruth Kastner herself had no problem with his reaction. This is the reason why I have trouble answering the title question myself.

This is why I brought up Feynman (who just like Ruth Kastner and John Cramer is not German):

Can it make sense to take a mere narrative seriously? (The narrative told by Feynman diagrams suggests itself, which also attaches "some picture to each symbol in the calculation".)

In fact, Cramer tried to "rescue" the Wheeler–Feynman absorber theory with his interpretation, and both Feynman and Wheeler have proposed many other ideas that are hard to make fully consistent and useful. Negative probabilities, anyone? Feynman officially dedicated those to David Bohm in 1987, but in fact first elaborated them earlier in his quantum computer proposal in 1981. But Feynman knew that many of his ideas were fascinating and tempting, and still risked to be unproductive or old wine in new bottles.

Feynman was well aware that taking ideas seriously is normally a bad idea, just like Ken G explained:

But if you mean "describes what is really happening" in some sort of unique or absolute way, I would simply point to the history of our entire endeavor to critique that attitude. It generally leads to the unscientific perspective that "we were all confused in the past but now we have it," an attitude we see throughout history and one that is no doubt just as wrong today as it has always been.

René Descartes comes to my mind. And still he is praised more than Feynman, who avoided those mistakes. But allowing to propose ideas without taking them seriously has its downsides too, because you can end-up in a situation with no common ground left.

But this "no common ground left" warning is actually a good reason for me not to take the transactional interpretation seriously. Even if Ruth Kastner's version of the transactional interpretation should turn out to be consistent, nearly nobody studied it, and even its proponents don't agree with each other. There is simply not enough "common ground" to be found here, for this to be a good investment of my time.

 

[PeterDonis]

whether John Cramer tried to communicate something that he personally felt correct and important, or whether he acted just like an overwhelmed student or LLM trying to give the impression that his explanations make sense

That question is one that only John Cramer can answer.

this "no common ground left" warning is actually a good reason for me not to take the transactional interpretation seriously. Even if Ruth Kastner's version of the transactional interpretation should turn out to be consistent, nearly nobody studied it, and even its proponents don't agree with each other. There is simply not enough "common ground" to be found here, for this to be a good investment of my time.

This looks like your answer to your own question is "no". Which means this thread can be closed, so it is.