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I find myself becoming more and more sensitive to this basic mistake: We know relativity is wrong somehow. We know quantum mechanics is wrong somehow. They're b

by jerf 3y ago

I find myself becoming more and more sensitive to this basic mistake: We know relativity is wrong somehow. We know quantum mechanics is wrong somehow. They're both incredibly correct with their predictions but they don't go together, so they can't both be right and in the end they both have to be wrong somehow. Two of the places where they are both clearly somehow wrong are gravity (completely missing from QM, incompatible with quantization in relativity) and time (both theories having problems with them in the extreme cases). Therefore, grand pronouncements about how the universe is "really" a static four-dimensional object "because that's what relativity says" are just wrong, for the exact same reasons. Perhaps even in the "not even wrong" sense, on the grounds that it is no different than taking Newtonian physics and making ground pronouncements about the nature of the universe. Newtonian physics implies things like "there can be no absolute speed limit in the universe"; not just that there isn't one, but that there can't be one for the transforms it uses to be valid. There is such a speed limit and the transforms it uses aren't valid. Declaring the universe to have this or that characteristic based on relativity is no different than declaring it must not have a speed-of-light because that's what Newtonian physics says. The only difference is that "everybody" knows the latter is wrong; the former is just as wrong. So in general getting too worked up over what Einstein's relativity says about the universe at this level is a waste of time, no pun intended. Science history being what it is, it is quite likely that if we ever do penetrate down to what time "really" is it'll be even more mind-blowing than a static four-dimensional universe, but that's a problem for the future. (And the current leading contenders in that theory race I'm not sure are any more disruptive than QM already was. Total chaos space/time at scales so small that they are in some sense literally microscopically microscopically microscopically microscopic may be vaguely unsettling, but to my mind doesn't seem to add anything philosophically material that QM didn't already introduce.)

hetman 3y ago
[flagged]
- bee_rider 3y ago
  It doesn’t look downvoted to me. I think this post of true and nice, but I can’t think of anything to discuss about it. Because of the way the ranking system works here, spats like the philosophy/physics thing will always rise to the top, I think.
- LegionMammal978 3y ago
  By my reading, a lot of it just boils down to the "all models are wrong, but some are useful" aphorism, but denigrating models' usefulness in a philosophical context, calling the implications of relativity and whatnot "a waste of time". I think this is overly reductive. Indeed, many consequences that follow from the nonexistence or impossibility of a certain thing, event, or effect are brittle to the physical model being refined to include additional effects. But plenty of important consequences follow from existence or possibility and can be directly supported through experimental evidence. For instance, Newtonian physics predict absolute simultaneity: if one observer measures that two events occurred at the same time, then all other observers will measure likewise, regardless of their relative position or velocity. But special relativity violates this, instead predicting relativity of simultaneity. As long as special relativity's predictions hold to any extent (which, experimentally, they do), then simultaneity is definitely relative and not absolute. There's no way to recover absolute simultaneity short of postulating a grand cosmic conspiracy. And learning that the arrow of time isn't absolute definitely isn't a waste of time! Also, I think it's unwarranted to say that just because some consequences of nonexistence have historically been invalidated in the past, all the consequences of nonexistence in our current theories are inevitably going to fall over with further evidence. Why should we expect a priori that we haven't yet discovered a single true invariant of our universe? After all, some observed invariants, such as the conservation of energy, have withstood the numerous revisions to our physical models, and it seems odd to blithely assert that they'll be invalidated any year now. In the limit, to say that exceptions will be discovered to every principle ever is to say that the universe doesn't run on any kind of laws. And if we do concede that at least some of our current models' invariants truly do hold in reality, then it's no longer a waste of time to study their implications, since some subset of our findings will remain just as accurate now matter how far our models are revised.
  - jerf 3y ago
    I would characterize it more as "All models are wrong, some are useful, but it is never useful to use a model in a domain it is known to be wrong in". We are extremely confident in the wrongness of relativity and QM in this matter, so using them in that particular way for philosophy is really a waste of time. One could sensibly write philosophy of the form "If string theory is true, then..." or "If Loop Quantum Gravity is true, then...", because while those are not proved, they are also not proved actively wrong in the relevant ways.
- dang 3y ago
  "Please don't comment about the voting on comments. It never does any good, and it makes boring reading." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html There's also the uncollected-garbage problem, which this case is a good example of. https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=by%3Adang%20garbage%20downvote&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
  - hetman 3y ago
    While I'm generally on board with this principle, I felt, given the nature of the conversation, this was a particularly egregious instance. Besides, sometimes new users can use a reminder. I'm generally not a fan of absolutist rules as they always tend to break down in some corner cases doing more harm than good (though of course we can disagree whether this was such a case). Either way, thank you for your reminder to my reminder :)
mannykannot 3y ago
Fair enough, though it's at least equally so for the intuitions of Bergson et. al.
whatshisface 3y ago
There could be a Newtonian speed limit if there was a drag force with a vertical asymptote in v through the medium that filled space.
- jerf 3y ago
  I would call that something other than Newtonian physics, since that would constitute adding a term of some sort to some important equations, but I'm willing to agree this is just arguing about definitions and it doesn't really matter in the end since it still wouldn't be right. :)
  - whatshisface 3y ago
    Forces are terms added to the left hand side of 0 = ma.
  - tsimionescu 3y ago
    Not exactly. The way physicists tried to reconcile Newtonian mechanics with the Maxwell equations was by imagining that the space between the Earth and the Sun (at least) is not a void, but that it is filled with an actual substance, the luminiferous ether. Light waves were posited to be mechanical waves in this substance, and the measured speed-of-light limit would have been a simple frame dragging effect: the moving train pulls the ether with it. Of course, the Michelson-Morley experiment proved that even if this substance exists, it can't be dragged around, so frame dragging can't be an explanation for the constant speed of light, making the whole idea unnecessary. Future observations predicted by SR and GR would probably not have been compatible anyway. But, getting back to your point, if this ether had existed and had been the medium through which light propagates and had been draggable by moving objects, then this would not have been a contradiction or even modification of Newtonian mechanics.
foobar1962 3y ago
> I find myself becoming more and more sensitive to this basic mistake: We know relativity is wrong somehow. We know quantum mechanics is wrong somehow. Please don't use the word "wrong". Alchemy is wrong. Astrology is wrong. Relativity and Quantum Mechanics get many things right but are probably "incomplete" in the same way Newtonian mechanics wasn't wrong, only incomplete.
- fiddlerwoaroof 3y ago
  Newton mechanics was wrong: because it didn’t account for the relativistic terms, all the equations are off by some amount. It turns out that we can ignore the error in practical contexts, but that’s still being “wrong”. Another example: the math of a geocentric solar system is often precise enough for practical purposes and so, when it’s simpler, it can be useful to use it instead of Newtonian or relativistic models. I think this is important because physicists that popularize often make grandiose claims about how reality is when they should know better and then these claims form popular imagination in ways that shutdown thought.
  - andyferris 3y ago
    I would say Newtonian mechanics is a good approximation (as it is accurate in its domain, plus easier to conceptialize and compute with than either QM or GR). Approximations aren't "wrong", they are just simplifications of something less wrong, usually in certain corner cases. Sometimes approximations are derived from the broader theory, and sometimes the broader theory comes later. (And of course, sometimes old theories are proven plain "wrong" by evidence and new theories, but those are things more like alchemy, or mistakes in math proofs, and less like Newton's laws). Finally, iff we follow your logic then we can say nothing is ever "right". Philosophically it may be useful to realize we may never know the ultimate truth with 100% certainty, but in everyday English "right" can simply mean "appropriate".
    - fiddlerwoaroof 3y ago
      > Approximations aren't "wrong", they are just simplifications of something less wrong, usually in certain corner cases. I think it’s true that wrongness is relative to the use-case. But, on the other hand, before things like the Ultraviolet Catastrophe and the Michelson-Morley experiment, a lot of physicists thought they had the big picture of the universe basically right and just had to fill in the details. The revolution of GR and QM was barely even suspected and this should give us pause when it comes to our confidence in the modern picture of the universe. Relativity and QM will always be useful as models of the spheres they model, but the worldview we’ve built on top of them could change drastically overnight (in historical terms).
skullgrid 3y ago
"All models are wrong, some are useful"

by jerf 3y ago

hetman 3y ago

[flagged]

bee_rider 3y ago
It doesn’t look downvoted to me. I think this post of true and nice, but I can’t think of anything to discuss about it. Because of the way the ranking system works here, spats like the philosophy/physics thing will always rise to the top, I think.
LegionMammal978 3y ago
By my reading, a lot of it just boils down to the "all models are wrong, but some are useful" aphorism, but denigrating models' usefulness in a philosophical context, calling the implications of relativity and whatnot "a waste of time". I think this is overly reductive. Indeed, many consequences that follow from the nonexistence or impossibility of a certain thing, event, or effect are brittle to the physical model being refined to include additional effects. But plenty of important consequences follow from existence or possibility and can be directly supported through experimental evidence. For instance, Newtonian physics predict absolute simultaneity: if one observer measures that two events occurred at the same time, then all other observers will measure likewise, regardless of their relative position or velocity. But special relativity violates this, instead predicting relativity of simultaneity. As long as special relativity's predictions hold to any extent (which, experimentally, they do), then simultaneity is definitely relative and not absolute. There's no way to recover absolute simultaneity short of postulating a grand cosmic conspiracy. And learning that the arrow of time isn't absolute definitely isn't a waste of time! Also, I think it's unwarranted to say that just because some consequences of nonexistence have historically been invalidated in the past, all the consequences of nonexistence in our current theories are inevitably going to fall over with further evidence. Why should we expect a priori that we haven't yet discovered a single true invariant of our universe? After all, some observed invariants, such as the conservation of energy, have withstood the numerous revisions to our physical models, and it seems odd to blithely assert that they'll be invalidated any year now. In the limit, to say that exceptions will be discovered to every principle ever is to say that the universe doesn't run on any kind of laws. And if we do concede that at least some of our current models' invariants truly do hold in reality, then it's no longer a waste of time to study their implications, since some subset of our findings will remain just as accurate now matter how far our models are revised.
- jerf 3y ago
  I would characterize it more as "All models are wrong, some are useful, but it is never useful to use a model in a domain it is known to be wrong in". We are extremely confident in the wrongness of relativity and QM in this matter, so using them in that particular way for philosophy is really a waste of time. One could sensibly write philosophy of the form "If string theory is true, then..." or "If Loop Quantum Gravity is true, then...", because while those are not proved, they are also not proved actively wrong in the relevant ways.
dang 3y ago
"Please don't comment about the voting on comments. It never does any good, and it makes boring reading." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html There's also the uncollected-garbage problem, which this case is a good example of. https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=by%3Adang%20garbage%20downvote&sort=byDate&type=comment https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
- hetman 3y ago
  While I'm generally on board with this principle, I felt, given the nature of the conversation, this was a particularly egregious instance. Besides, sometimes new users can use a reminder. I'm generally not a fan of absolutist rules as they always tend to break down in some corner cases doing more harm than good (though of course we can disagree whether this was such a case). Either way, thank you for your reminder to my reminder :)

mannykannot 3y ago

Fair enough, though it's at least equally so for the intuitions of Bergson et. al.

whatshisface 3y ago

There could be a Newtonian speed limit if there was a drag force with a vertical asymptote in v through the medium that filled space.

jerf 3y ago
I would call that something other than Newtonian physics, since that would constitute adding a term of some sort to some important equations, but I'm willing to agree this is just arguing about definitions and it doesn't really matter in the end since it still wouldn't be right. :)
- whatshisface 3y ago
  Forces are terms added to the left hand side of 0 = ma.
- tsimionescu 3y ago
  Not exactly. The way physicists tried to reconcile Newtonian mechanics with the Maxwell equations was by imagining that the space between the Earth and the Sun (at least) is not a void, but that it is filled with an actual substance, the luminiferous ether. Light waves were posited to be mechanical waves in this substance, and the measured speed-of-light limit would have been a simple frame dragging effect: the moving train pulls the ether with it. Of course, the Michelson-Morley experiment proved that even if this substance exists, it can't be dragged around, so frame dragging can't be an explanation for the constant speed of light, making the whole idea unnecessary. Future observations predicted by SR and GR would probably not have been compatible anyway. But, getting back to your point, if this ether had existed and had been the medium through which light propagates and had been draggable by moving objects, then this would not have been a contradiction or even modification of Newtonian mechanics.

foobar1962 3y ago

> I find myself becoming more and more sensitive to this basic mistake: We know relativity is wrong somehow. We know quantum mechanics is wrong somehow. Please don't use the word "wrong". Alchemy is wrong. Astrology is wrong. Relativity and Quantum Mechanics get many things right but are probably "incomplete" in the same way Newtonian mechanics wasn't wrong, only incomplete.

fiddlerwoaroof 3y ago
Newton mechanics was wrong: because it didn’t account for the relativistic terms, all the equations are off by some amount. It turns out that we can ignore the error in practical contexts, but that’s still being “wrong”. Another example: the math of a geocentric solar system is often precise enough for practical purposes and so, when it’s simpler, it can be useful to use it instead of Newtonian or relativistic models. I think this is important because physicists that popularize often make grandiose claims about how reality is when they should know better and then these claims form popular imagination in ways that shutdown thought.
- andyferris 3y ago
  I would say Newtonian mechanics is a good approximation (as it is accurate in its domain, plus easier to conceptialize and compute with than either QM or GR). Approximations aren't "wrong", they are just simplifications of something less wrong, usually in certain corner cases. Sometimes approximations are derived from the broader theory, and sometimes the broader theory comes later. (And of course, sometimes old theories are proven plain "wrong" by evidence and new theories, but those are things more like alchemy, or mistakes in math proofs, and less like Newton's laws). Finally, iff we follow your logic then we can say nothing is ever "right". Philosophically it may be useful to realize we may never know the ultimate truth with 100% certainty, but in everyday English "right" can simply mean "appropriate".
  - fiddlerwoaroof 3y ago
    > Approximations aren't "wrong", they are just simplifications of something less wrong, usually in certain corner cases. I think it’s true that wrongness is relative to the use-case. But, on the other hand, before things like the Ultraviolet Catastrophe and the Michelson-Morley experiment, a lot of physicists thought they had the big picture of the universe basically right and just had to fill in the details. The revolution of GR and QM was barely even suspected and this should give us pause when it comes to our confidence in the modern picture of the universe. Relativity and QM will always be useful as models of the spheres they model, but the worldview we’ve built on top of them could change drastically overnight (in historical terms).

skullgrid 3y ago

"All models are wrong, some are useful"