Feb 9, 2023 08:25 PM
(This post was last modified: Feb 9, 2023 08:29 PM by C C.)
https://bigthink.com/13-8/quantum-mechanics-philosophy/
EXCERPTS (Marcelo Gleiser): . . . In one corner stands those who think that the wavefunction is an element of reality, that it describes reality as it is. This way of thinking is sometimes called the ontic interpretation, from the term ontology, which in philosophy means the stuff that makes up reality. People who follow the ontic school would say that even though the wavefunction does not describe something palpable, like the particle’s position or its momentum, its absolute square represents the probability of measuring this or that physical property — the superpositions that it does describe are a part of reality.
In the other corner stand those who think that the wavefunction is not an element of reality. Instead, they see a mathematical construct that allows us to make sense of what we find in experiments. This way of thinking is sometimes called the epistemic interpretation, from the term epistemology in philosophy. [...] There is no need to attribute any kind of reality to the wavefunction. It simply represents potentialities — the possible outcomes of a measurement. (The great physicist Freeman Dyson once told me that he considered the whole debate a huge waste of time. To him, the wavefunction was never intended to be a real thing.)
Note the importance in all this of measurements. Historically, the epistemic view goes back to the Copenhagen interpretation, the hodgepodge of ideas spearheaded by Niels Bohr and carried forward by his younger, powerhouse colleagues such as Werner Heisenberg, Wolfgang Pauli, Pascual Jordan, and many others.
This school of thought is sometimes unjustly called the “shut up and calculate approach” due to its insistence that we do not know what the wavefunction is, only what it does. It tells us we accept the superpositions of possible states, coexisting before a measurement is made, as a pragmatic description of what we cannot know. Upon measurement, the system collapses into just one of the possible states: the one that is measured. Yes, it is weird to state that a wavy thing, spread across space, instantaneously goes into a single position (a position that lies within what is allowed by the Uncertainty Principle). [...] It introduces the possibility that the measurer has something to do with determining reality. But the theory works, and for all practical purposes, that is what really matters.
At its essence, the ontic vs. epistemic debate hides the ghost of objectivity in science. Onticists deeply dislike the notion that observers could have anything to do with determining the nature of reality. Is an experimenter really determining whether an electron is here or there? One ontic school known as the Many Worlds interpretation would say instead that all possible outcomes are realized when a measurement is performed. It’s just that they are realized in parallel worlds, and we only have direct access to one of them — namely, the one we exist in...
[...] Other ontic approaches require, for example, adding elements of reality to the quantum mechanical description. For example, David Bohm proposed expanding the quantum mechanical prescription by adding a pilot wave with the explicit role of guiding the particles into their experimental outcomes. The price for experimental certainty, here, is that this pilot wave acts everywhere at once, which in physics means that it has nonlocality. Many people, including Einstein, have found this impossible to accept.
On the epistemic side, interpretations are just as varied. The Copenhagen interpretation leads the pack... (MORE - missing details)
RELATED (wikipedia): List of influential interpretations
EXCERPTS (Marcelo Gleiser): . . . In one corner stands those who think that the wavefunction is an element of reality, that it describes reality as it is. This way of thinking is sometimes called the ontic interpretation, from the term ontology, which in philosophy means the stuff that makes up reality. People who follow the ontic school would say that even though the wavefunction does not describe something palpable, like the particle’s position or its momentum, its absolute square represents the probability of measuring this or that physical property — the superpositions that it does describe are a part of reality.
In the other corner stand those who think that the wavefunction is not an element of reality. Instead, they see a mathematical construct that allows us to make sense of what we find in experiments. This way of thinking is sometimes called the epistemic interpretation, from the term epistemology in philosophy. [...] There is no need to attribute any kind of reality to the wavefunction. It simply represents potentialities — the possible outcomes of a measurement. (The great physicist Freeman Dyson once told me that he considered the whole debate a huge waste of time. To him, the wavefunction was never intended to be a real thing.)
Note the importance in all this of measurements. Historically, the epistemic view goes back to the Copenhagen interpretation, the hodgepodge of ideas spearheaded by Niels Bohr and carried forward by his younger, powerhouse colleagues such as Werner Heisenberg, Wolfgang Pauli, Pascual Jordan, and many others.
This school of thought is sometimes unjustly called the “shut up and calculate approach” due to its insistence that we do not know what the wavefunction is, only what it does. It tells us we accept the superpositions of possible states, coexisting before a measurement is made, as a pragmatic description of what we cannot know. Upon measurement, the system collapses into just one of the possible states: the one that is measured. Yes, it is weird to state that a wavy thing, spread across space, instantaneously goes into a single position (a position that lies within what is allowed by the Uncertainty Principle). [...] It introduces the possibility that the measurer has something to do with determining reality. But the theory works, and for all practical purposes, that is what really matters.
At its essence, the ontic vs. epistemic debate hides the ghost of objectivity in science. Onticists deeply dislike the notion that observers could have anything to do with determining the nature of reality. Is an experimenter really determining whether an electron is here or there? One ontic school known as the Many Worlds interpretation would say instead that all possible outcomes are realized when a measurement is performed. It’s just that they are realized in parallel worlds, and we only have direct access to one of them — namely, the one we exist in...
[...] Other ontic approaches require, for example, adding elements of reality to the quantum mechanical description. For example, David Bohm proposed expanding the quantum mechanical prescription by adding a pilot wave with the explicit role of guiding the particles into their experimental outcomes. The price for experimental certainty, here, is that this pilot wave acts everywhere at once, which in physics means that it has nonlocality. Many people, including Einstein, have found this impossible to accept.
On the epistemic side, interpretations are just as varied. The Copenhagen interpretation leads the pack... (MORE - missing details)
RELATED (wikipedia): List of influential interpretations
