7 ms·

Physics isn't simple. It took (literally) thousands of years of study by very smart people to get to the point where what we call "intuition" about the physical

by sidlls 5y ago

Physics isn't simple. It took (literally) thousands of years of study by very smart people to get to the point where what we call "intuition" about the physical world is what it is. And, as any physicist who paid attention in class will tell you, even that intuition isn't really right. Any simplicity observed in physics is born of long familiarity, or is the result of underlying complexities being masked or approximated away.

danbruc 5y ago
Physics is simple in a certain sense and the paper explains this. In theory the force acting on something you drop could be a function of the state of every particle in the universe and each one could contribute with a different weight. But this is not the case, things are only influenced by things nearby and the weights involved are not arbitrary, the charge of each electron, for example, is the same. In that sense physics is unbelievable simple as compared to what it could be.
- dekhn 5y ago
  nobody has proved the conjecture "things are only influenced by things nearby" this is one of the largest ongoing arguments in QM (locality: https://web.mit.edu/asf/www/Press/Holmes_Physics_World_2017.pdf https://web.mit.edu/asf/www/Press/Holmes_Physics_World_2017....) We also don't know for sure the "constants" are constant throughout the universe (spatially and temporally) This is assumed for now, and seems almost certainly true. I think it's unsafe to assume the above are Absolutely True and that that's why physics is simple.
  - danbruc 5y ago
    nobody has proved the conjecture "things are only influenced by things nearby" this is one of the largest ongoing arguments in QM This is a much more nuanced matter. Non-locality as in global wave function collapse or Bohmian mechanics has not the same consequences as classical non-locality, there is no causal influence from things you do to an entangled particle at the other end of the universe. Also to entangle particles they have to first interact locally before they can be separated. We also don't know for sure the "constants" are constant throughout the universe (spatially and temporally) This is assumed for now, and seems almost certainly true. This does not really change the argument, even if, for example, the fine-structure constant is not constant after all, then there will most likely be a hand full of other constants that describe how it varies over space and time. This is very different from every electron having a unique electric charge that is not governed by anything and the only way to figure it out is to measure it for each electron. It would also probably make a difference how values are distributed, are the charges of the electrons nicely distributed and vary by a factor of two or ten? Some statistical theory could probably deal with that. But what if there is no nice distribution, if values vary by hundreds of orders of magnitude, if the expectation value or the variance of the charge is infinite? I am certainly unqualified to make any definitive statements but I can imagine physics to be weird to the point that it becomes mathematically intractable or at least only produces useless answers because of the amount of uncertainty that enters the equations. In any case, we know that the universe is simple to a very good approximation, even if fundamentally everything depends on everything and the electron charges are all random, those effects are small and we can have a good approximation with simple theories.

by sidlls 5y ago

danbruc 5y ago

Physics is simple in a certain sense and the paper explains this. In theory the force acting on something you drop could be a function of the state of every particle in the universe and each one could contribute with a different weight. But this is not the case, things are only influenced by things nearby and the weights involved are not arbitrary, the charge of each electron, for example, is the same. In that sense physics is unbelievable simple as compared to what it could be.

dekhn 5y ago
nobody has proved the conjecture "things are only influenced by things nearby" this is one of the largest ongoing arguments in QM (locality: https://web.mit.edu/asf/www/Press/Holmes_Physics_World_2017.pdf https://web.mit.edu/asf/www/Press/Holmes_Physics_World_2017....) We also don't know for sure the "constants" are constant throughout the universe (spatially and temporally) This is assumed for now, and seems almost certainly true. I think it's unsafe to assume the above are Absolutely True and that that's why physics is simple.
- danbruc 5y ago
  nobody has proved the conjecture "things are only influenced by things nearby" this is one of the largest ongoing arguments in QM This is a much more nuanced matter. Non-locality as in global wave function collapse or Bohmian mechanics has not the same consequences as classical non-locality, there is no causal influence from things you do to an entangled particle at the other end of the universe. Also to entangle particles they have to first interact locally before they can be separated. We also don't know for sure the "constants" are constant throughout the universe (spatially and temporally) This is assumed for now, and seems almost certainly true. This does not really change the argument, even if, for example, the fine-structure constant is not constant after all, then there will most likely be a hand full of other constants that describe how it varies over space and time. This is very different from every electron having a unique electric charge that is not governed by anything and the only way to figure it out is to measure it for each electron. It would also probably make a difference how values are distributed, are the charges of the electrons nicely distributed and vary by a factor of two or ten? Some statistical theory could probably deal with that. But what if there is no nice distribution, if values vary by hundreds of orders of magnitude, if the expectation value or the variance of the charge is infinite? I am certainly unqualified to make any definitive statements but I can imagine physics to be weird to the point that it becomes mathematically intractable or at least only produces useless answers because of the amount of uncertainty that enters the equations. In any case, we know that the universe is simple to a very good approximation, even if fundamentally everything depends on everything and the electron charges are all random, those effects are small and we can have a good approximation with simple theories.