Correct me if I am wrong, the "paradoxes" described here are due to our lack of understanding of the theory right and not because the theory is inconsistent.
Why have so many physicists shrugged off the paradoxes of quantum mechanics?
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Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#52Earlier quoted context omitted.
We may be using different definitions of the word philosophical. I'm classifying anything that can be decided experimentally as scientific. These interpretations are identical from an experimental standpoint.
That's a circular argument. It doesn't prove that experimental differences between interpretations are impossible. The existence of such a proof would provide a genuine scientific basis for not continuing to address the problem. Without that proof, the problem remains open.
It will surprise you to hear, just as it suprised me, that MWI and Copenhagen have been axiomatically identical from day one. I know what you are thinking, something like, "if the problem was closed we wouldn't be talking about it, so it must be open." Yeah, well...
There is a list of axioms of quantum mechanics, Copenhagen and MWI disagree only on how you get to them. (And also on their conceptual interpretation). That's why they're called interpretations of quantum mechanics, not theories of quantum mechanics.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#53Correct me if I am wrong, the "paradoxes" described here are due to our lack of understanding of the theory right and not because the theory is inconsistent.
In what circumstance does that not describe a paradox?
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#54> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
> with an error that is so small that you can just ignore the uncertainty and approximate them as classical objects. I’d say that’s the gist of it, that we cannot “just ignore” the uncertainty because it’s too small, because if you do that then your model and the real world are indeed different. Also, at the end of it all what does “too small” mean? “Too small” compared to what? To a galaxy? To a super-nova? To a pla…
"Too small" means either it can not be detected experimentally, or even in principle, depending on whether you are allowing gedankenexperiments.
I don't think it is reasonable to expect our models to be identical to reality. Otherwise, they wouldn't be models, they would be reality. A theory is correct if it produces experimentally verified predictions.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#55> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
> with an error that is so small that you can just ignore the uncertainty and approximate them as classical objects. I’d say that’s the gist of it, that we cannot “just ignore” the uncertainty because it’s too small, because if you do that then your model and the real world are indeed different. Also, at the end of it all what does “too small” mean? “Too small” compared to what? To a galaxy? To a super-nova? To a pla…
> To say nothing of the fact that comparing a number to physical stuff will eventually bring you head on against Zeno’s paradox, one way or the other.
Zeno's paradoxes are soluble by basic calculus. Once you distinguish between countable and uncountable infinities, the problem of crossing a bounded interval in finite time ceases to be paradoxical.
This is basically to say I don't think this is a particular problem for the resolution of outstanding inconsistencies in theoretical physics.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#56Earlier quoted context omitted.
No, there is not. The Everett aka many-worlds interpretation demonstrates that you can explain the observed effects of measurement without invoking "collapse" of the wave function, and without reference to anything outside of QM.
Many Worlds still owes us an explanation of the apparently huge difference between this, the actual, world and all the other apparently not quite so actual ones, does it not? The two most promising ideas (IMO) are the idea that the "wave function collapse" is a non-physical event describing a change in our knowledge, the quantum informatics approach as per Philip Ball's recent RI lecture,[1] and the "Relational" inte…
Many Worlds still owes us an explanation of the apparently huge difference between this, the actual, world and all the other apparently not quite so actual ones, does it not?
No.
For a start, there is no evidence that the ones you are calling "not quite so actual" are any less actual than the one we share an experience of.
Continuing on, the interpretation does not attempt to explain the phenomena of perceived consciousness. That is as much out of its remit as abiogenesis is out of the remit of Darwin's theory of evolution. Those problems are different in kind, much harder, and have to be addressed by very different theories.
Everett addressed a precise problem. That problem is explaining why, to the extent that QM describes an observer, the act of observation must turn that observer into a superposition of observers. Each of which has observed an apparent collapse, and none of which can interact further in any meaningful way.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#57They aren't paradoxes of quantum mechanics. They are a paradox between how we intuitively expect the world to work and reality. Our intuition is wrong.
Yes there are. Even without invoking any philosophical issues, quantum mechanics admits it's not self-contained. It takes measurement - the act of an outsider interacting with a system, which collapses the wavefunction, as a postulate. Measurement is not described by quantum mechanics.
The act of making a measurement/observation is nothing more than an interaction where the system is exchanging information or this this case quantum states which is described by quantum mechanics. I don't get where this "special/outside" observer coming from.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#58It seems to me that the resolution of the quantum mysteries might come from three sources: (1) the Holographic Principle, (2) Dark Matter, and (3) the Planck Length.
1. The Holographic Principle. The universe looks three dimensional but fundamentally it is different. 3-D space is a projection from some 2-D circuit board. If I believe that, then I have no problem hearing about (a) hidden variables or (b) spooky action at a distance.
2. Dark Matter. The universe is 98% unaccounted for. Could it be that space is not a vacuum? Perhaps we are like fish in water, moving through it but taking it for granted. How can "something" have travelled through "nothing" (a vacuum) anyway? Maybe there's an aether after all.
3. The Planck Length. Space is not an infinitely smooth line but instead there is a fundamental bit size. We thought atoms were it, that's how they got their name ("atom" means uncuttable). Later we found inside them protons and neutrons, and within those, quarks. Someone therefore might imagine that we could go on subdividing forever. But the Planck Length is a hard stop: 0.000000000000000000000000000000016 of a millimeter.
If we are immersed in invisible water, then it's unsurprising that there are "waves." And yet if there is a fundamental smallest size, like the grains of photographic film, then it's not all that weird to say that you can think of matter as particles. Perhaps that's all that a "particle" is, a piece of the water.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#59> Bohr postulated a distinction between the quantum world and the world of everyday objects. A “classical” object is an object of everyday experience. It has, for example, a definite position and momentum, whether observed or not. A “quantum” object, such as an electron, has a different status; it’s an abstraction. Some properties, such as electrical charge, belong to the electron abstraction intrinsically, but other…
> with an error that is so small that you can just ignore the uncertainty and approximate them as classical objects. I’d say that’s the gist of it, that we cannot “just ignore” the uncertainty because it’s too small, because if you do that then your model and the real world are indeed different. Also, at the end of it all what does “too small” mean? “Too small” compared to what? To a galaxy? To a super-nova? To a pla…
[For a technical answer, it's interesting to read the comment by AnimalMuppet https://news.ycombinator.com/item?id=19700979 ]
What??? Every Physicist believes that the uncertainty principle apply to any object from galaxies to elementary particles. So if you try to not apply the uncertainly principle in a particle collision in the CERN, they will think that you are crazy. But if you try to add the uncertainty principle to the simulation of the movement of the objects in a galaxy, they will think that you are crazy too because the difference is very small and the calculations are much more complicated.
There are some application of the uncertainly principle to neutron stars, and IIRC to the background radiation. Nobody thinks that the uncertainly principle doesn't apply to big objects, it just that in most cases the difference is ridiculously small.
Perhaps the “mathematization” of the physical world is a leaking abstraction, perhaps no. We don't know. If you can prove that “we’ll never really know what the world is made up of” you will get a Nobel prize. But you will need a real proof, not handwaving.
Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?
#60Earlier quoted context omitted.
MWI is what happens when you don't require the existence of anything extra (collapse phenomenon). It's like how isn't an unexplained phenomenon--it results from the evolution of the observer's perspective. In MWI there is no event corresponding to collapse for the same reason that Gallileo's model doesn't have any correlate of epicycles.
In MWI the event corresponding to collapse is the supposed appearance of an entire universe, which is - conveniently - impossible to detect. And which "explains" any one timeline of experience as "Actually, that's still just random." So MWI goes from "That's random and we don't know why" to "That's random, we don't know why, but now we've added a universe too, although we can't prove it exists." Something about this…
And yet there is an intermediate version. Which is that we can have an "observer" that is a moderately complex QM system where further post-observations are possible though difficult. And we can conduct experiments along that line and observe the growing difficulty of future interaction as systems get complex.
Unsurprisingly, these experiments with "partial collapse" produce exactly the predicted results of QM. And are exactly in line with, "And if the system gets more complicated still, collapse becomes irreversible." (Where "more complicated still" is very simple compared to ordinary macroscopic objects.)