If I may jump in here… You can get from common-sense physical concepts to quantum physics in a finite number of steps, but the resulting construct almost certainly does not satisfy your criteria for being a theory. Roughly speaking, you can start with a few common-sense concepts like object, motion, mass, force, then proceed to their mathematical incarnation in Newton’s laws and Maxwell’s field equations. At this point you have classical physics, which offers a framework for talking about point particles with mass and charge, and force fields which pervade space and are described by a vector at every point in space, interacting according to some law. Then, when you proceed to quantum mechanics, you describe the particles and fields, not by saying exactly where the particle is or exactly where the field vectors are pointing, but rather by using probabilities for all the distinct classical possibilities. But you don’t even use ordinary probability functions; instead, each possibility has a complex number attached—basically, a two-dimensional vector, and then the probability is the square of the length of the vector.
As you may have surmised, these layered concepts are now several steps removed from a physics which offers exact, deterministic descriptions of recognizably physical objects. However, there isn’t a complete disconnection. At the bottom you’re still talking about objects and forces acting on them. You still have conservation of energy, straight-line motion unless a force acts, etc. The description is fuzzy and the predictions are just probabilities, but even the peculiar framework of complex numbers is just a slight modification of the mathematics of motion and interaction appearing in the classical theory.
By your conceptual standards, this is indeed not a theory. It’s a hybrid of sensible concepts (the classical picture) and mathematical rules (the quantum mathematics). The result does not provide a clear picture of reality and yet the physical concepts are indispensible in grounding the mathematics anyway. Hundreds of physicists across the decades have tried to restore clarity to physics by producing a deeper theory, but the mainstream has mostly adapted itself to simply working within the hybrid framework. This sequence of posts is about a radical attempt to make sense of the probabilities by saying that there are parallel universes; all possibilities are actual, existing alongside each other in some ultimate hyperspace. However, the complex numbers are still left over, unexplained, but attached to each parallel universe. The parallel universes are the “configurations” and the attached complex numbers are the “amplitudes”. So it’s still a hybrid construct in which the conceptual physical picture comes with some unintegrated mathematics that’s just tacked on… Beyond this point, you can (1) retain the multiverse concept but keep looking for a version which makes more sense (2) tell yourself that amplitudes-attached-to-configurations is just how reality is and you need to adapt your standards to this (3) look for an entirely different explanation.
I did mean you, specifically. Learning QM has been compared to learning to ride a bicycle. You don’t do that by first defining your terms, you just get out there and do it, and it’s hard to reduce the knowledge of how to ride a bike to definitions. When people learn QM, they slide past some difficulties of logic, and are “rewarded” with the ability to quantitatively describe and predict atomic behavior.
There is a huge spectrum of attitudes among physicists towards the logical or conceptual basis of QM. On this site, they want to make sense of QM by adopting a radical new picture of reality in which there are “flows” of “amplitude-stuff” through the hyperspace of parallel universes. This is a genuine faction of opinion among physicists. But then you have the more down-to-earth people who tell you that quantum physics is just like classical physics, except that everything is a little “fuzzy” or “uncertain”. This view is something of a philosophical placebo which allows its adherents to feel that there is no conceptual problem in QM.
Regarding even more basic matters, like what’s going on in the very first steps towards the mathematization of physical concepts, that is a discussion that interests me, but we would first need to agree on exactly what the “issues” are, which might take a while. So I think we should have it privately, and then report back to the site, rather than flailing around in public. My mail is mporter at gmail.com, please contact me there if you want to continue this dialogue.
Learning QM has been compared to learning to ride a bicycle. You don’t do that by first defining your terms, you just get out there and do it, and it’s hard to reduce the knowledge of how to ride a bike to definitions.
This may indeed be the case, but taking the outside view—if I didn’t know you were talking about QM, but knew it was about some purported scientific theory—giving a free pass to the usual strict rationalist requirement to “define your terms clearly” would seem pretty dubious. There are a lot of ways to build whole systems out of equivocations and other such semantic fudging, a lot of religious argument operates that way, and so on.
If I may jump in here… You can get from common-sense physical concepts to quantum physics in a finite number of steps, but the resulting construct almost certainly does not satisfy your criteria for being a theory. Roughly speaking, you can start with a few common-sense concepts like object, motion, mass, force, then proceed to their mathematical incarnation in Newton’s laws and Maxwell’s field equations. At this point you have classical physics, which offers a framework for talking about point particles with mass and charge, and force fields which pervade space and are described by a vector at every point in space, interacting according to some law. Then, when you proceed to quantum mechanics, you describe the particles and fields, not by saying exactly where the particle is or exactly where the field vectors are pointing, but rather by using probabilities for all the distinct classical possibilities. But you don’t even use ordinary probability functions; instead, each possibility has a complex number attached—basically, a two-dimensional vector, and then the probability is the square of the length of the vector.
As you may have surmised, these layered concepts are now several steps removed from a physics which offers exact, deterministic descriptions of recognizably physical objects. However, there isn’t a complete disconnection. At the bottom you’re still talking about objects and forces acting on them. You still have conservation of energy, straight-line motion unless a force acts, etc. The description is fuzzy and the predictions are just probabilities, but even the peculiar framework of complex numbers is just a slight modification of the mathematics of motion and interaction appearing in the classical theory.
By your conceptual standards, this is indeed not a theory. It’s a hybrid of sensible concepts (the classical picture) and mathematical rules (the quantum mathematics). The result does not provide a clear picture of reality and yet the physical concepts are indispensible in grounding the mathematics anyway. Hundreds of physicists across the decades have tried to restore clarity to physics by producing a deeper theory, but the mainstream has mostly adapted itself to simply working within the hybrid framework. This sequence of posts is about a radical attempt to make sense of the probabilities by saying that there are parallel universes; all possibilities are actual, existing alongside each other in some ultimate hyperspace. However, the complex numbers are still left over, unexplained, but attached to each parallel universe. The parallel universes are the “configurations” and the attached complex numbers are the “amplitudes”. So it’s still a hybrid construct in which the conceptual physical picture comes with some unintegrated mathematics that’s just tacked on… Beyond this point, you can (1) retain the multiverse concept but keep looking for a version which makes more sense (2) tell yourself that amplitudes-attached-to-configurations is just how reality is and you need to adapt your standards to this (3) look for an entirely different explanation.
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I did mean you, specifically. Learning QM has been compared to learning to ride a bicycle. You don’t do that by first defining your terms, you just get out there and do it, and it’s hard to reduce the knowledge of how to ride a bike to definitions. When people learn QM, they slide past some difficulties of logic, and are “rewarded” with the ability to quantitatively describe and predict atomic behavior.
There is a huge spectrum of attitudes among physicists towards the logical or conceptual basis of QM. On this site, they want to make sense of QM by adopting a radical new picture of reality in which there are “flows” of “amplitude-stuff” through the hyperspace of parallel universes. This is a genuine faction of opinion among physicists. But then you have the more down-to-earth people who tell you that quantum physics is just like classical physics, except that everything is a little “fuzzy” or “uncertain”. This view is something of a philosophical placebo which allows its adherents to feel that there is no conceptual problem in QM.
Regarding even more basic matters, like what’s going on in the very first steps towards the mathematization of physical concepts, that is a discussion that interests me, but we would first need to agree on exactly what the “issues” are, which might take a while. So I think we should have it privately, and then report back to the site, rather than flailing around in public. My mail is mporter at gmail.com, please contact me there if you want to continue this dialogue.
Thank you very much for your response and your offer.
This may indeed be the case, but taking the outside view—if I didn’t know you were talking about QM, but knew it was about some purported scientific theory—giving a free pass to the usual strict rationalist requirement to “define your terms clearly” would seem pretty dubious. There are a lot of ways to build whole systems out of equivocations and other such semantic fudging, a lot of religious argument operates that way, and so on.