Why have so many physicists shrugged off the paradoxes of quantum mechanics? • Hacker News Board

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#81

Post by yk » Sat, Apr 20, 2019, 9:59 AM UTC

ttlei wrote: post #51

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.

The paradoxes are because the theory is formulated in terms of complicated mathematical expressions that do not map neatly onto a naive understanding of macroscopic reality.

The entire problem of learning QM is, that one has to learn not to trust ones intuition and instead look at what the math is showing. For example the supposed paradox of being sometimes a wave and sometimes a particle is only there if you insist to use the macroscopic analogies of wave and particle. In the full theory, the object is always a vector in an Hillbertspace, which is a concept that does not map neatly onto some combination of wave and particle.

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#82

Post by tus87 » Sat, Apr 20, 2019, 10:09 AM UTC

> Pascual Jordan, an important member of Bohr’s circle, cut the Gordian knot: An electron does not have a position until it is observed; the observation is what compels it to assume one. Quantum mechanics makes statistical predictions about where it is more or less likely to be observed.

The things physicists will say instead of "we don't know the answer".

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#83

Post by gxwmg » Sat, Apr 20, 2019, 10:20 AM UTC

For the same reason psychologists have shrugged off the fact that most papers cannot be replicated.

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#84

Post by cygx » Sat, Apr 20, 2019, 10:25 AM UTC

Sylos wrote: post #35

gus_massa wrote: post #2

> 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…

> This is a common error. Macroscopic "everyday" objects don't have a definite position and momentum. Macroscopic objects are quantum objects. But when the mass is big enough, the position and momentum can be defined simultaneously with an error that is so small that you can just ignore the uncertainty and approximate them as classical objects. To put this into simpler terms: Whenever we measure something, we need to…

The observer effect and the uncertainty principle are not the same thing.

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#85

Post by atomack » Sat, Apr 20, 2019, 10:33 AM UTC

pdkl95 wrote: post #78

atomack wrote: post #68

Earlier quoted context omitted.

I think david927's intuition is more correct here. The uncertainty in the position and momentum is intrinsic to quantum mechanics - it's built into the 'wave function'. The suggestion that if one pushes away something by throwing something else builds on a purely classical intuition and wouldn't require quantum mechanics to explain if this was all we observed. The uncertainty in quantum mechanics is fundamental (to q…

3Blue1Brown has an extremely good explanation[1] of the intrinsic uncertainty, and why it's separate from measurement uncertainty. (the previous episode[2] is a recommended prerequisite for background on how the Fourier Transform works) > emerges through a different, as yet unknown, mechanism. In 3Blue1Bron's explanation[1], he shows how the intrinsic uncertainty is an inherent trade-off of trying to measure both pos…

Yes, I like these sources too. Good for building intuition. I would just add that Heisenberg-like here means that both systems share features of wave mechanics. Doppler type effects aren't quantum mechanical though.

When I suggest the mechanism is unknown, I mean that Heisenberg uncertainty is a postulate of quantum mechanics. In other words the fundamental reason that quantum mechanics should appeal to wave mechanics isn't really established - we don't really know yet the fundamental objects and interactions that lead to quantum mechanics (despite much effort).

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#86

Post by jcoffland » Sat, Apr 20, 2019, 10:37 AM UTC

All human models of reality are flawed. It is improbable that our small minds will ever comprehend the nature of the universe in it's entirety. Each answer uncovers more questions, more paradoxes.

That is not to say we should not continue to try to understand the world around us. Only that logic dictates that we proceed with humility.

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#87

Post by atomack » Sat, Apr 20, 2019, 10:37 AM UTC

bonoboTP wrote: post #71

atomack wrote: post #68

Earlier quoted context omitted.

I think david927's intuition is more correct here. The uncertainty in the position and momentum is intrinsic to quantum mechanics - it's built into the 'wave function'. The suggestion that if one pushes away something by throwing something else builds on a purely classical intuition and wouldn't require quantum mechanics to explain if this was all we observed. The uncertainty in quantum mechanics is fundamental (to q…

Why unknown? Heisenberg's uncertainty principle can be derived mathematically, using a property of the Fourier transform. It has nothing to do with disturbing the system during measurement.

I'd say that's more a mathematical statement than physical derivation. The effort of subjects like string theory is to lay down fundamental objects and interactions from which other theories (quantum mechanics, gravity) emerge. But I don't think there is a final word at the moment of what the fundamental theories than result in quantum mechanics should look like.

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#88

Post by cygx » Sat, Apr 20, 2019, 10:40 AM UTC

dghf wrote: post #76

TheOtherHobbes wrote: post #40

Earlier quoted context omitted.

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…

> In MWI the event corresponding to collapse is the supposed appearance of an entire universe, which is - conveniently - impossible to detect. My layman's understanding was that MWI doesn't postulate multiple universes. Rather, it posits that all particles are always in superpositions of states. What looks like a collapse to a single state is actually the particles under observation getting entangled with the particl…

Your description looks right to me. Note that the many-worlds interpretation was originally named the theory of the universal wave-function. You get there by trying to eliminate wave-function collapse and Heisenberg cuts.

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#89

Post by laszlokorte » Sat, Apr 20, 2019, 10:43 AM UTC

ChrisSD wrote: post #18

nikofeyn wrote: post #10

Earlier quoted context omitted.

you could say that about any paradox. it other words, it isn't a helpful position because it doesn't give any insight. why even have the word paradox? plus, our intuition is just as much a part of reality as your "reality".

A paradox is essentially a logical contradiction. As far as we know such contradictions don't occur in nature. Paradoxes indicate that there is a flaw in either our theory or our understanding of our theory.

Actually a paradox is something that appears to be a contradiction. It comes from the greek for "contrary to expectation". So often a paradox is about wrong expectations and not a contradiction in of it self.

Re: Why have so many physicists shrugged off the paradoxes of quantum mechanics?

#90

Post by bhouston » Sat, Apr 20, 2019, 10:50 AM UTC

I think the observes are in super position and measurement collapses us and the world. Thus there are no nonlocal effects rather we just get rid of multiple universes which were averages together and pick one, or at least the subset of possible universes that correspond to that particular measurement. Thus instead of non local effects one selects from multiple existing solutions at present and discard the rest.

I think this makes a lot more sense.

The other alternative was we are in a simulation and it has variable levels of resolution (wave verses particle) and it will computer higher resolutions on demand (eg observers), but that these on demand increases in resolution affect the simulation going forward. This seems to be overly complex thus I prefer the first interpretation.

I am a layman in this area so I am probably wrong.

There must already exist a formal name for this? Isn't this where multiverses comes into play?