PAP: Do we create the very reality that we observe?
https://csferrie.medium.com/do-we-create...62d1fab93b
EXCERPTS: John Wheeler called it the Participatory Anthropic Principle. It goes something like this. The answers we get from posing questions to Nature depend very much on the questions we ask. Without any questions, nothing would be answered — hence we are participants in the bringing about of events...
[...] The seeds of the participatory universe were sown in a thought experiment called the delayed choice experiment ... One of two things must be true. Either your choice sends a message back in time to tell the photon how to behave, or the photon doesn’t really exist as a definite entity until it is observed. Within a small laboratory experiment, this all seems academic. But Wheeler was thinking on a cosmic scale.
If you point your telescope in the right direction, you can create a double-slit experiment the size of the universe! [...] Every single photon from that star could have taken one of many paths to reach us here on Earth. The telescope used for the photo detects the path, and many photons project an image of a ring around the lensing galaxy. If instead, the light from all directions was combined before detection, then a wave-like pattern would be detected, implying the photon took all paths.
Surely, if the light chooses one path or another, it did so many billions of years ago when it encountered the intervening galaxy. Yet, how the photon manifests in the world is only decided up here and now, through the way we choose to arrange our telescope. From your point of view, that photon has been waiting for billions of years for you to come along and choose how it should manifest in the world.
Recall how the game 20 Questions works. [...] But let’s change it up a bit. Suppose there were 20 of us “answerers” and you had to ask each question to one person in succession...
[...] From your perspective, the game is no different. You assume the 20 people all agreed on the answer — transistor radio — before the game began. But here’s the kicker. In this game of 20 Questions, each of the 20 participants agreed beforehand to not think of something. The only thing they agreed to do was answer yes or no in a way that didn’t contradict any previous answer. Only when the last question was asked did “transistor radio” come into existence as the answer.
The point is subtle, but obvious in hindsight. Before you started asking the questions, there was no “answer.” It was only through your choice of question that an eventual answer materialized in the world. Wheeler called this “it from bit” — the physical world (“it”) is brought about through asking it yes or no questions (“bits”). Why is the universe the way it is? Turns out, it literally depends who’s asking... (MORE - missing details)
Quantum Bayesianism: our part in creating reality
https://iai.tv/articles/quantum-mechanic..._auid=2020
EXCERPTS: I first started to care about the "interpretation" of quantum physics several years after I began using it. Many physicists don't care about such things at all, or they grow out of it rather than into it. It does indubitably feel strange that we would have to "interpret" a scientific theory; such language seems like it would belong more to critics of free verse or abstract art. [...] But sometimes, when we're trying to develop the theory in new directions, or find the clearest way to teach it to the next generation, or we've just had one too many late nights wondering what it all means, we have to get our fingers philosophical.
[...] I found myself drawn to one that had only recently been articulated, the QBism laid out by Christopher Fuchs and Ruediger Schack. ... The QBist take on quantum mechanics is that, at its core, quantum mechanics is a theory of actions and consequences. A QBist looks for objectivity on a different level than the adherents of many other interpretations.
[...] We resort to jargon like "normative structural realism" and "participatory realism" to give our intuitions shape and form. No existing school of philosophy seems quite right for where the physics wants to go; we'll agree with many predecessors, but often with a caveat or a qualification. Perhaps the best place to start is with that capital B.
The Q in QBism came from Quantum, of course, and the B originated with "Bayes". In the wide spectrum of ways to think about probability, "Bayesianism" encompasses a variety of schools of thought which hold that a probability is a value that an agent asserts, a quantitative expression of a degree of belief. Probabilities encode expectations, and without someone around to do the expecting, there would be no probabilities. Before there were weather forecasters, there were no forecasts, even though the world had plenty of weather. In the proto-QBist days, around the turn of the millennium, the idea was just that the probabilities in quantum physics could be understood in a Bayesian way. But "Bayesian" is a broad label, and those early attempts were not very good at narrowing it down; nor, as further investigation revealed, were they internally self-consistent. That early "Quantum Bayesianism" took several more years to mature into QBism.
QBism regards quantum mechanics as a "user's manual". In this interpretation, quantum mechanics is about what happens at the interface between an agent and the rest of nature. Most of the mathematical entities employed in the theory, like the "wavefunctions" of which so much has been said, boil down to being bundles of expectations. Whose expectations? Yours, or mine, or those of whoever has picked up the user's manual and is trying to benefit from its guidance. Expectations for what? For the consequences of the user's own actions. What kind of actions? Any kind, in principle...
[...] Now, for all our sympathies with [John] Wheeler, QBism does diverge from his vision and terminology in some ways. For one, "observer" is to us far too passive a word; it carries the connotation of leaning back, not of pounding the pavement and wearing out the shoe-leather. That's why we talk instead of agents, as I did above. So, “agent-participancy”, then.
But Wheeler did have his finger on the right question. We need to nail down that "quantum principle"! The next level of sophistication, the next stage of understanding, is surely to abstract away the "agent-". What can we say of the situations where the "ubiquitous process" has nobody along for the ride, no agent Alice to partake? The first step to answering that, we think, is to quantify just how involved an agent is in eliciting an outcome. [...] So far, this is still only imagery. But by teasing apart the mathematics of quantum theory, unraveling the convenient conventions from the deep enigmas, perhaps the imagery can be made more precise and more evocative than ever before... (MORE - missing details)
https://csferrie.medium.com/do-we-create...62d1fab93b
EXCERPTS: John Wheeler called it the Participatory Anthropic Principle. It goes something like this. The answers we get from posing questions to Nature depend very much on the questions we ask. Without any questions, nothing would be answered — hence we are participants in the bringing about of events...
[...] The seeds of the participatory universe were sown in a thought experiment called the delayed choice experiment ... One of two things must be true. Either your choice sends a message back in time to tell the photon how to behave, or the photon doesn’t really exist as a definite entity until it is observed. Within a small laboratory experiment, this all seems academic. But Wheeler was thinking on a cosmic scale.
If you point your telescope in the right direction, you can create a double-slit experiment the size of the universe! [...] Every single photon from that star could have taken one of many paths to reach us here on Earth. The telescope used for the photo detects the path, and many photons project an image of a ring around the lensing galaxy. If instead, the light from all directions was combined before detection, then a wave-like pattern would be detected, implying the photon took all paths.
Surely, if the light chooses one path or another, it did so many billions of years ago when it encountered the intervening galaxy. Yet, how the photon manifests in the world is only decided up here and now, through the way we choose to arrange our telescope. From your point of view, that photon has been waiting for billions of years for you to come along and choose how it should manifest in the world.
Recall how the game 20 Questions works. [...] But let’s change it up a bit. Suppose there were 20 of us “answerers” and you had to ask each question to one person in succession...
[...] From your perspective, the game is no different. You assume the 20 people all agreed on the answer — transistor radio — before the game began. But here’s the kicker. In this game of 20 Questions, each of the 20 participants agreed beforehand to not think of something. The only thing they agreed to do was answer yes or no in a way that didn’t contradict any previous answer. Only when the last question was asked did “transistor radio” come into existence as the answer.
The point is subtle, but obvious in hindsight. Before you started asking the questions, there was no “answer.” It was only through your choice of question that an eventual answer materialized in the world. Wheeler called this “it from bit” — the physical world (“it”) is brought about through asking it yes or no questions (“bits”). Why is the universe the way it is? Turns out, it literally depends who’s asking... (MORE - missing details)
Quantum Bayesianism: our part in creating reality
https://iai.tv/articles/quantum-mechanic..._auid=2020
EXCERPTS: I first started to care about the "interpretation" of quantum physics several years after I began using it. Many physicists don't care about such things at all, or they grow out of it rather than into it. It does indubitably feel strange that we would have to "interpret" a scientific theory; such language seems like it would belong more to critics of free verse or abstract art. [...] But sometimes, when we're trying to develop the theory in new directions, or find the clearest way to teach it to the next generation, or we've just had one too many late nights wondering what it all means, we have to get our fingers philosophical.
[...] I found myself drawn to one that had only recently been articulated, the QBism laid out by Christopher Fuchs and Ruediger Schack. ... The QBist take on quantum mechanics is that, at its core, quantum mechanics is a theory of actions and consequences. A QBist looks for objectivity on a different level than the adherents of many other interpretations.
[...] We resort to jargon like "normative structural realism" and "participatory realism" to give our intuitions shape and form. No existing school of philosophy seems quite right for where the physics wants to go; we'll agree with many predecessors, but often with a caveat or a qualification. Perhaps the best place to start is with that capital B.
The Q in QBism came from Quantum, of course, and the B originated with "Bayes". In the wide spectrum of ways to think about probability, "Bayesianism" encompasses a variety of schools of thought which hold that a probability is a value that an agent asserts, a quantitative expression of a degree of belief. Probabilities encode expectations, and without someone around to do the expecting, there would be no probabilities. Before there were weather forecasters, there were no forecasts, even though the world had plenty of weather. In the proto-QBist days, around the turn of the millennium, the idea was just that the probabilities in quantum physics could be understood in a Bayesian way. But "Bayesian" is a broad label, and those early attempts were not very good at narrowing it down; nor, as further investigation revealed, were they internally self-consistent. That early "Quantum Bayesianism" took several more years to mature into QBism.
QBism regards quantum mechanics as a "user's manual". In this interpretation, quantum mechanics is about what happens at the interface between an agent and the rest of nature. Most of the mathematical entities employed in the theory, like the "wavefunctions" of which so much has been said, boil down to being bundles of expectations. Whose expectations? Yours, or mine, or those of whoever has picked up the user's manual and is trying to benefit from its guidance. Expectations for what? For the consequences of the user's own actions. What kind of actions? Any kind, in principle...
[...] Now, for all our sympathies with [John] Wheeler, QBism does diverge from his vision and terminology in some ways. For one, "observer" is to us far too passive a word; it carries the connotation of leaning back, not of pounding the pavement and wearing out the shoe-leather. That's why we talk instead of agents, as I did above. So, “agent-participancy”, then.
But Wheeler did have his finger on the right question. We need to nail down that "quantum principle"! The next level of sophistication, the next stage of understanding, is surely to abstract away the "agent-". What can we say of the situations where the "ubiquitous process" has nobody along for the ride, no agent Alice to partake? The first step to answering that, we think, is to quantify just how involved an agent is in eliciting an outcome. [...] So far, this is still only imagery. But by teasing apart the mathematics of quantum theory, unraveling the convenient conventions from the deep enigmas, perhaps the imagery can be made more precise and more evocative than ever before... (MORE - missing details)