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Too many people, including physicists, confuse theories with reality. Quantum mechanics is a very powerful theory that correctly predicts a lot of observed phen

Too many people, including physicists, confuse theories with reality. Quantum mechanics is a very powerful theory that correctly predicts a lot of observed phenomena. But while QM talks about a wavefunction, it doesn't mean the wavefunction actually exists. I myself particularly like the Everett interpretation, which some believe implies a multiverse, but I don't think the actual existence of a multiverse is necessary.

moonchild 6y ago
When you say 'theory', I think you mean 'model'.
lmm 6y ago
What other definition is there for saying that something exists, than that it correctly predicts observed phenomena? If you say that the table in front of me exists, surely that's nothing more or less than saying that the concept of a table correctly predicts the table-like sensations you see and feel.
- guerrilla 6y ago
  There's an entire field of philosophy called ontology which includes metaontology and it answers your question as "many definitions." I recommend this book [1] by Berto and Plebani. SEP [2] also has about a dozen articles on the ontology of quantum mechanics and quantum physics more generally. [1]. https://www.bloomsbury.com/us/ontology-and-metaontology-9781472573308/ https://www.bloomsbury.com/us/ontology-and-metaontology-9781... [2]. https://plato.stanford.edu/contents.html#q https://plato.stanford.edu/contents.html#q
- someguyorother 6y ago
  To me, "exists" is stronger than "predicts observation", although I can't entirely describe how, except by example. Let's say you're in a game. You can create a physics of the game world based on how that game behaves. However, the game world doesn't exist, as such. It's the result of a pattern produced by a computer, interpreted by our minds, which fills in the blanks and makes the game world feel more real than it is. It makes sense that an account of existence should either include the substructure (in this case, the computer) or the observer (in this case, the mind doing the filling-in), or possibly both. On the other hand, a description of the behavior of the system is much simpler. Another example: simulation hypothesis people sometimes talk about the possibility of "breaking out" of the simulation, as if the simulation is less somehow less true than whatever is behind it. But from a predicting-observed-phenomenon perspective, what you describe by physics exists. So the distinction between the rules of physics that apply in a certain domain because you're in a simulation, and the rules of physics that apply in another domain once you find a way to break out, is entirely artificial. That people don't see it that way seems to indicate that they mean something else by existence.
  - GoblinSlayer 6y ago
    Without relying on a thing that actually exists - a computer running the game - you can't properly describe the behavior of the game.
GoblinSlayer 6y ago
In Everett interpretation wave function actually exists. As actually as you can get. Well, quantum state exists, wave function describes what is the state. There's a physical object described by mathematical formula, this relation is called physical meaning.

moonchild 6y ago

When you say 'theory', I think you mean 'model'.

lmm 6y ago

What other definition is there for saying that something exists, than that it correctly predicts observed phenomena? If you say that the table in front of me exists, surely that's nothing more or less than saying that the concept of a table correctly predicts the table-like sensations you see and feel.

guerrilla 6y ago
There's an entire field of philosophy called ontology which includes metaontology and it answers your question as "many definitions." I recommend this book [1] by Berto and Plebani. SEP [2] also has about a dozen articles on the ontology of quantum mechanics and quantum physics more generally. [1]. https://www.bloomsbury.com/us/ontology-and-metaontology-9781472573308/ https://www.bloomsbury.com/us/ontology-and-metaontology-9781... [2]. https://plato.stanford.edu/contents.html#q https://plato.stanford.edu/contents.html#q
someguyorother 6y ago
To me, "exists" is stronger than "predicts observation", although I can't entirely describe how, except by example. Let's say you're in a game. You can create a physics of the game world based on how that game behaves. However, the game world doesn't exist, as such. It's the result of a pattern produced by a computer, interpreted by our minds, which fills in the blanks and makes the game world feel more real than it is. It makes sense that an account of existence should either include the substructure (in this case, the computer) or the observer (in this case, the mind doing the filling-in), or possibly both. On the other hand, a description of the behavior of the system is much simpler. Another example: simulation hypothesis people sometimes talk about the possibility of "breaking out" of the simulation, as if the simulation is less somehow less true than whatever is behind it. But from a predicting-observed-phenomenon perspective, what you describe by physics exists. So the distinction between the rules of physics that apply in a certain domain because you're in a simulation, and the rules of physics that apply in another domain once you find a way to break out, is entirely artificial. That people don't see it that way seems to indicate that they mean something else by existence.
- GoblinSlayer 6y ago
  Without relying on a thing that actually exists - a computer running the game - you can't properly describe the behavior of the game.

GoblinSlayer 6y ago

In Everett interpretation wave function actually exists. As actually as you can get. Well, quantum state exists, wave function describes what is the state. There's a physical object described by mathematical formula, this relation is called physical meaning.