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Funny that we call it classical. Newton wouldn't have called it so. Maybe we should categorize sciences based on the spatial scale at which they operate.A speci

by zkmon 1y ago

Funny that we call it classical. Newton wouldn't have called it so. Maybe we should categorize sciences based on the spatial scale at which they operate.A specific scale might define a world that has it's logic system, purpose, reasoning etc. For example, quantum scale, human scale and cosmic scales have their own physics, logic and causality.

kergonath 1y ago
> Newton wouldn't have called it so. Of course. To him that would be modern mechanics. Or just mathematical natural philosophy, or whatever. > Maybe we should categorize sciences based on the spatial scale at which they operate. That would not be very useful, because there is no boundary. Nothing in general relativity says "below this everything is Newtonian". As a matter of fact we need to consider relativistic effects in quantum chemistry calculations that involve some heavy elements, at length scales smaller than 0.1 nm. Similarly, they just gave a Nobel prize for work on "Quantum properties on a human scale". > For example, quantum scale, human scale and cosmic scales have their own physics, logic and causality. That is not at all how these frameworks are built, and that is not the dominant epistemological approach. The mainstream view is that there is a theory of everything that exists but is unknown to us, and that our various theories are approximations of that theory under different assumptions. They look categorically different because we don’t understand the overarching framework, not because nature is fundamentally different depending on scale. Also, I don’t see how the logic is fundamentally different between e.g. quantum mechanics and general relativity. Both rely heavily on things like Hamiltonian mechanics or symmetries. Some behaviours are different (like photons following geodesics and not straight lines, or superpositions of quantum states), but these are not a fundamental problem: a straight line is a limit case of a geodesic in a flat space, and a unique state is a limit case of superposition. I am not saying that everything is fine and we know everything, just that there is no clear boundary between the situations in which different theories are required and we cannot neatly decompose the universe into different realms where different theories apply.
- zkmon 1y ago
  From my little knowledge, logic at Quantum scale appears quite different: * Things don't have their own location or identity * Spatial and temporal extents don't exist * Something may be true and false at the same time, or concept of true and false may not be defined * cause and effect goes for a toss, as behavior of time is different * Existence and non-existence co-exist, or come into existence together Similar effects at relatively-infinite scale (maybe purely mathematical) * Comparisons (big/small/equal) breakdown * Regular arithmetic and logic breaks down
  - simiones 1y ago
    Most of these things are misunderstandings of quantum mechanics, as we know it today. The main thing that is at the root of all of them is the word "things". In QM, the ground truth of the world is the wavefunction of the system. The wavefunction assigns some amplitude (potentially 0) to any possible state of the system that it describes. It then evolves purely deterministically from past to future, according to Schrodinger's equation (or Dirac's equation, if you want to discuss speeds close to that of light). The only kink is interaction with a measurement device (what constitutes a measurement device is one of the big mysteries that we don't yet have an answer for). After a measurement, the wavefunction collapses non-deterministically to one of the states that the measurement device was set up to detect, with a probability that is proportional to the amplitude of the wave function of that state. Now, this is the "ground truth" of QM. Everything else, such as particles and space-time and so on are just stories we tell to make sense of the wavefunction and its behavior. Sometimes those descriptions break down, and they start assigning weird fanciful ideas, such as retrocausality etc - but these just prove that the stories are wrong, that they are misinterpreting the math of the wavefunction. I'd also note that the main "time is weird" factoid you encounter related to QM experiments, the delayed-choice quantum eraser, is mostly a misunderstanding / sensationalization of the actual physics and the experiment. It again only proves that certain interpretations of what the wavefunction and its collapse represent are not temporally consistent, but the direct conclusion from this should be that the interpretations are wrong, not that "cause and effect goes for a toss, as behavior of time is different".
IAmBroom 1y ago
We call music from Newton's age "classical". As the past recedes, "the golden age" advances in time. "Hollaback Girl" is now a classic oldie.
- seanhunter 1y ago
  The music of Newton’s age is Baroque music. Classical music either refers to the whole tradition of Western serious art music (starting approximately with Palestrina and continuing to the current day) or it refers to the period after Baroque. So “ Baroque” is J.S. Bach, Handel, Charpentier, Purcell etc (1600-1750 ish), “classical” is mozart, J.C. Bach, Hayden etc up to Beethoven (1750ish-1800ish). Classical mechanics as I was taught it is not to do with the time period,it means “mechanics when you don’t need to worry about relativity or quantum anything “.
hyperjeff 1y ago
These days “classical” just distinguishes all things quantum from non-quantum. General relativity is considered a classical theory, for example.
seanhunter 1y ago
That is very definitely classical mechanics, just that it emphasises the Lagrangian and Hamiltonian formulations rather than the Newtonian one (they explain their rationale for this in the beginning). These three formulations of classical mechanics are entirely equivalent though. When you learn mechanics at first you don’t learn the Hamiltonian at all and the Lagrangian isn’t mentioned by name but by formulating some problems in terms of kinetic and potential energy rather than equations of motion and showing that is equivalent. (Eg when I did mechanics we did that for simple harmonic motion). I mean Newton wouldn’t recognize most of what we teach as Calculus because we use Leibnitz’ notation[1] or Lagrange’s notation almost exclusively, and only use Newton’s notation for derivatives with respect to time and don’t ever use Newton’s terminology (fluxions etc). [1] So named because it was mostly invented by Euler.

by zkmon 1y ago

kergonath 1y ago

> Newton wouldn't have called it so. Of course. To him that would be modern mechanics. Or just mathematical natural philosophy, or whatever. > Maybe we should categorize sciences based on the spatial scale at which they operate. That would not be very useful, because there is no boundary. Nothing in general relativity says "below this everything is Newtonian". As a matter of fact we need to consider relativistic effects in quantum chemistry calculations that involve some heavy elements, at length scales smaller than 0.1 nm. Similarly, they just gave a Nobel prize for work on "Quantum properties on a human scale". > For example, quantum scale, human scale and cosmic scales have their own physics, logic and causality. That is not at all how these frameworks are built, and that is not the dominant epistemological approach. The mainstream view is that there is a theory of everything that exists but is unknown to us, and that our various theories are approximations of that theory under different assumptions. They look categorically different because we don’t understand the overarching framework, not because nature is fundamentally different depending on scale. Also, I don’t see how the logic is fundamentally different between e.g. quantum mechanics and general relativity. Both rely heavily on things like Hamiltonian mechanics or symmetries. Some behaviours are different (like photons following geodesics and not straight lines, or superpositions of quantum states), but these are not a fundamental problem: a straight line is a limit case of a geodesic in a flat space, and a unique state is a limit case of superposition. I am not saying that everything is fine and we know everything, just that there is no clear boundary between the situations in which different theories are required and we cannot neatly decompose the universe into different realms where different theories apply.

zkmon 1y ago
From my little knowledge, logic at Quantum scale appears quite different: * Things don't have their own location or identity * Spatial and temporal extents don't exist * Something may be true and false at the same time, or concept of true and false may not be defined * cause and effect goes for a toss, as behavior of time is different * Existence and non-existence co-exist, or come into existence together Similar effects at relatively-infinite scale (maybe purely mathematical) * Comparisons (big/small/equal) breakdown * Regular arithmetic and logic breaks down
- simiones 1y ago
  Most of these things are misunderstandings of quantum mechanics, as we know it today. The main thing that is at the root of all of them is the word "things". In QM, the ground truth of the world is the wavefunction of the system. The wavefunction assigns some amplitude (potentially 0) to any possible state of the system that it describes. It then evolves purely deterministically from past to future, according to Schrodinger's equation (or Dirac's equation, if you want to discuss speeds close to that of light). The only kink is interaction with a measurement device (what constitutes a measurement device is one of the big mysteries that we don't yet have an answer for). After a measurement, the wavefunction collapses non-deterministically to one of the states that the measurement device was set up to detect, with a probability that is proportional to the amplitude of the wave function of that state. Now, this is the "ground truth" of QM. Everything else, such as particles and space-time and so on are just stories we tell to make sense of the wavefunction and its behavior. Sometimes those descriptions break down, and they start assigning weird fanciful ideas, such as retrocausality etc - but these just prove that the stories are wrong, that they are misinterpreting the math of the wavefunction. I'd also note that the main "time is weird" factoid you encounter related to QM experiments, the delayed-choice quantum eraser, is mostly a misunderstanding / sensationalization of the actual physics and the experiment. It again only proves that certain interpretations of what the wavefunction and its collapse represent are not temporally consistent, but the direct conclusion from this should be that the interpretations are wrong, not that "cause and effect goes for a toss, as behavior of time is different".

IAmBroom 1y ago

We call music from Newton's age "classical". As the past recedes, "the golden age" advances in time. "Hollaback Girl" is now a classic oldie.

seanhunter 1y ago
The music of Newton’s age is Baroque music. Classical music either refers to the whole tradition of Western serious art music (starting approximately with Palestrina and continuing to the current day) or it refers to the period after Baroque. So “ Baroque” is J.S. Bach, Handel, Charpentier, Purcell etc (1600-1750 ish), “classical” is mozart, J.C. Bach, Hayden etc up to Beethoven (1750ish-1800ish). Classical mechanics as I was taught it is not to do with the time period,it means “mechanics when you don’t need to worry about relativity or quantum anything “.

hyperjeff 1y ago

These days “classical” just distinguishes all things quantum from non-quantum. General relativity is considered a classical theory, for example.

seanhunter 1y ago

That is very definitely classical mechanics, just that it emphasises the Lagrangian and Hamiltonian formulations rather than the Newtonian one (they explain their rationale for this in the beginning). These three formulations of classical mechanics are entirely equivalent though. When you learn mechanics at first you don’t learn the Hamiltonian at all and the Lagrangian isn’t mentioned by name but by formulating some problems in terms of kinetic and potential energy rather than equations of motion and showing that is equivalent. (Eg when I did mechanics we did that for simple harmonic motion). I mean Newton wouldn’t recognize most of what we teach as Calculus because we use Leibnitz’ notation[1] or Lagrange’s notation almost exclusively, and only use Newton’s notation for derivatives with respect to time and don’t ever use Newton’s terminology (fluxions etc). [1] So named because it was mostly invented by Euler.