Comment by jerf | Hacker News Reader

Comment by jerf | Hacker News Reader

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.)

> 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.

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.

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".

> 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).

But they are wrong, that doesn’t make the not useful though

Newton was wrong if his project was about uncovering the deep workings of nature. His assumptions were wrong and don’t work. They will never work. They are not “incomplete”.

They are practical though. In that sense astrology can be said to be practical too.. hides.

> Alchemy is wrong. Astrology is wrong.

I think you are partly right. Quantum mechanics and general relativity are incomplete rather than wrong. I don’t think either has been falsified, it’s more that they are just useless in specific cases.

This is in contrast with Newtonian mechanics, which implies Galilean transformation when changing reference frames, which looks right at our usual scales, but is plainly wrong in the general case.

However, the things you mention are not even wrong. As in, they are not falsifiable so you cannot say whether they are right or wrong in theory.

> I don’t think either has been falsified, it’s more that they are just useless in specific cases.

Of course they have. If you try to use SR or GR to predict how particles behave, you will get none of the quantum effects we have observed experimentally.

If you try to use QM or QFT to predict how the planets move* or at least how black holes move, you'll get predictions that don't agree with what telescopes have observed.

So yes, both of the theories have already been falsified.

* I have been told that there are some ways to account for gravity in regular QM in a way similar to GR that essentially work until you get to the kinds of strong fields near a black hole, where they break down again.

astrology is not wrong, because it doesn't say anything provable. it just is. it's like saying poetry is wrong or paintings are wrong

Astrologers often make very falsifiable claims, such as "you'll meet the man of your dreams, because Mercury is ascending". Those claims are of course false.

"All models are wrong, some are useful"

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.

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. :)

Forces are terms added to the left hand side of 0 = ma.

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.

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

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