Why is Quantum thoery so confusing that no body actually understand it ?

[Rico L]

It says that:

I think I can safely say that nobody understands quantum mechanics...Do not keep saysing to yourself, if you can possibly avoid it. But how can it be like that? Because you will go "down the drain" into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that.
by Richard Feynman


what does he mean by "down to the drain" and "blind alley"? . .

why is quantum world so confusing?

can anyone just come up with an example would be great



cheers..

 

[Rico L]

I mean I have read a few articles about them and I think its mainly to do with possibilities.. I haven't gone deep enough to find it confusing... so can anyone sort of explain for bit .. an example would be great


thanks

 

[madhatter106]

entanglement, unitary evolution (continuous, deterministic) and state reduction (discontinuous, probabilistic).

quantum jumping, I'll state that I had only read the textbooks and listened to lectures for the last 15yrs not as a student but as a hobby, weird I know. Now that I have a bit more spare time I'm taking the time to learn more of the math. I'll say that it to me seems to further divide probabilistic vs state vector.
just by measuring the momentum of the particle it jumps into an eigenstate of the momentum operator and if I've got this right it's now a wave form and spread over all of space. but if you try and measure this new state it jumps again, I think this is the collapse of the wave function or state reduction to probabilistic. So based on that the measuring is part of the system and each measurement effects it state so that you'll always have a missing piece.
That's how i see it for now, still learning and I'll say that don't expect it to get easier or make more sense. I enjoy going down the 'rabbit hole' though.

 

[LostConjugate]

There is a fundamental limitation with any attempt to self reference your own design. This is something computer programmers discovered when trying to build the ultimate debugger. We are trying to understand the elementary particles that make up the same tools we are using to measure them.

 

[Rico L]

i see..

cheers ppl

 

[dulrich]

I think there is a more fundamental reason here. It's not that we can't understand it because it is confusing. It's not confusing -- it's unimaginable. When we say we understand something this usually means we have explained the new thing in terms we have experienced. It's like going to a foreign culture: there is no decent frame of reference. But then you talk to people and learn what things are like. You gain experience.

But quantum mechanics is different because we cannot gain this direct experience. So we try and grasp it through analogies. But every analogy is to something macroscopic: is it a particle (read: billiard ball) or a wave (read: water wave). Well, it's a bit of both -- which makes no sense for billiard balls and water waves. Nonetheless that's the way the microscopic works.

 

[Fredrik]

The problem isn't with QM, which is just a set of rules that tells us how to calculate probabilities of possibilities. The problem is with the idea that "QM describes the world out there". It's very tempting to believe that this statement is true, or even obvious, but it's probably not even logically consistent.

 

[Rico L]

I think there is a more fundamental reason here. It's not that we can't understand it because it is confusing. It's not confusing

thats confusing.. :) lol

i see your point

 

[IcedEcliptic]

There is also the reality that without an understanding of linear algebra, understanding QM is going to be approximate, and confusing.

 

[rewebster]

I think its more like a spider web in a dream*.



edit:
*nightmare

 

[waht]

I don't like that Feynman's quote. It's too ambiguous and open to interpretation. QM is a well defined mathematical framework that is based on postulates the same way special relativity is, and it makes reliable predictions up to a certain limit.

What we don't understand is the theory of everything, if there ever is such an idea.

 

[rewebster]

I don't like that Feynman's quote. It's too ambiguous and open to interpretation. QM is a well defined mathematical framework that is based on postulates the same way special relativity is, and it makes reliable predictions up to a certain limit.

What we don't understand is the theory of everything, if there ever is such an idea.

I have a feeling it will be easier to understand than quantum

 

[qsa]

thats confusing.. :) lol

i see your point

It is classical physics that was confusing for me. Although, I could do it with my eyes shut I could not really understand why. It was the same old thing, we do experiments plot and get the equations no explanation as such( like f=GMm/r^2). Thank god for QM/QFT things make much more sense.

 

[GeorgCantor]

The problem isn't with QM, which is just a set of rules that tells us how to calculate probabilities of possibilities. The problem is with the idea that "QM describes the world out there". It's very tempting to believe that this statement is true, or even obvious, but it's probably not even logically consistent.

Any formalism that makes stunningly correct predictions about the world out there must be describing the world out there. Proposing otherwise is probably not even logically consistent.

 

[IcedEcliptic]

Any formalism that makes stunningly correct predictions about the world out there must be describing the world out there. Proposing otherwise is probably not even logically consistent.

That is absurd.

 

[GeorgCantor]

That is absurd.

No. What is very obviously absurd is that an ape-like creature that historically has just descended from the trees, actually thinks that reality MUST conform to his/her prejudice and intuition. I don't think that nature, the world, reality, or call it whatever, cares about how you want the world to be. In a wider context, everything is absurd - how reality works is absurd, existence is absurd, life is absurd, self-awareness is absurd, but it's a brute fact. Face it or suggest a reason why it must NOT be absurd.

It must all be stemming from the fact that we thought for so long that we understood reality and existence. We do not, and this is exactly 100.00% certain. We have no proper understanding of what is going on, how it is going on and why it is going on. We are still dumb animals born in a fairly absurd reality. Face this fact, or join the religious who think they have the important answers figured out.

 

[magpies]

So the choice is to remain monkey or be a man? Hurm...

I think the thing QM is that it's concepts are fairly simple on the surface but have a level of complexity at the bottom that you would need a super computer and 10 years at MIT to understand. So while everyone thinks they understand QM at the basics the reality is only a select few really get what its saying about the world. It's sort of like poker or chess :) Everyone thinks they know how to play yet only a select few end up at the championships year after year. Sorry if this comment gets the thread locked :( :(

 

[Fredrik]

Any formalism that makes stunningly correct predictions about the world out there must be describing the world out there. Proposing otherwise is probably not even logically consistent.

No. What is very obviously absurd is that an ape-like creature that historically has just descended from the trees, actually thinks that reality MUST conform to his/her prejudice and intuition.

You don't even seem to realize that the claim you made is only based on your own prejudice and intuition. The truth of the proposition that QM describes the physical system under consideration even at times between state preparation and measurement does not follow logically from the truth of the proposition that QM describes the system immediately after each measurement.

It's quite bizarre that you take what I said as evidence that I think reality must conform to my prejudice and intuition. The only unsual thing I've done is to let go of the prejudice that every theory that makes accurate predictions about probabilities of possible results of experiments must be a description of reality at all times.

I'm not saying that QM isn't a description of a physical system. I'm saying that maybe it is, and maybe it isn't. The information we get from experiments just isn't enough to rule one of these options out. I'm also not saying that the idea that "QM describes a physical system at all times" is logically inconsistent. As far as I know, it isn't. But it does seem to imply the existence of many worlds. So as far as I can tell, the idea that QM describes reality and the idea that reality consists of only our universe, can't both be true.

It must all be stemming from the fact that we thought for so long that we understood reality and existence. We do not, and this is exactly 100.00% certain. We have no proper understanding of what is going on, how it is going on and why it is going on. We are still dumb animals born in a fairly absurd reality. Face this fact, or join the religious who think they have the important answers figured out.

There are times and places where comments like these are appropriate, but this is definitely not one of them.

 

[Antiphon]

Quantum mechanics as a tool is understood by those who use it, professional physicists. What knowbody knows is why nature is this way. Most specifically, from Feynman, nobody knows why or how quantum interference takes place in nature. But that it does, and that it quantum theory is incredibly accurate is not in dispute.

As to the absurdity or not of asserting that QM describes thecreal world, it's a matter of fidelity. The 4 elements, air, earth, fire, water describe the world to a certain fidelity. The fidelity of QM is a lot higher but it is not the last word in understanding the physical world. In fact it's just the opening sentence. Humans have not addresed the how or why of it yet.

 

[GeorgCantor]

You don't even seem to realize that the claim you made is only based on your own prejudice and intuition. The truth of the proposition that QM describes the physical system under consideration even at times between state preparation and measurement does not follow logically from the truth of the proposition that QM describes the system immediately after each measurement.

I understand your unwillingness to say specifically that QM describes the system between measurements, but if everytime we do a measurement/observation we get an accurate result that exactly conforms to the calculations, what could it be that the said formalism is describing except reality itself? How could it even be otherwise? We have to be logical and logic dictates that if said theory makes correct predictions(so far QM is the most successful theory there is in physics), then it must describe reality. Be specific, how could it be otherwise? How could the world be different than QM describes, if QM's predictions are always accurate to a striking degree of precision?

I'm not saying that QM isn't a description of a physical system. I'm saying that maybe it is, and maybe it isn't. The information we get from experiments just isn't enough to rule one of these options out.

Right. But what is the other option and how would that be? We have a theory that makes correct predictions but you are saying it might not be a description of reality? How so? Are you proposing abandoning causality at certain level? If so, we'd be essentially abandoning science as we know it. I am not saying reality isn't that way, but if there is no fundamental cause as to why things happen the way they do at the macro scale, that'd be the end of the quest for answers to the deep philosophical questions. And abandoning causality opens the door to a myriad of "God did it" interpretations.

I'm not saying that QM isn't a description of a physical system. I'm saying that maybe it is, and maybe it isn't. The information we get from experiments just isn't enough to rule one of these options out. I'm also not saying that the idea that "QM describes a physical system at all times" is logically inconsistent. As far as I know, it isn't. But it does seem to imply the existence of many worlds. So as far as I can tell, the idea that QM describes reality and the idea that reality consists of only our universe, can't both be true.

Correct but MWI could be said to be "flowing" out of the QM formalism and experiments. As such, it is also a correct description of the world out there, as per qm formalism. Even between measurements and interactions.

 

[Fredrik]

I understand your unwillingness to say specifically that QM describes the system between measurements, but if everytime we do a measurement/observation we get an accurate result that exactly conforms to the calculations, what could it be that the said formalism is describing except reality itself?

A fictional universe with the property that a description of some aspect of it resembles a description of the real universe.

We have to be logical and logic dictates that if said theory makes correct predictions(so far QM is the most successful theory there is in physics), then it must describe reality.

That conclusion does not follow from that premise.

Be specific, how could it be otherwise? How could the world be different than QM describes, if QM's predictions are always accurate to a striking degree of precision?

I think this reveals what your mistake is. You're making an "argument from incredulity". You don't see how what I'm suggesting is possible, so it must be impossible. That's not a logical argument, it's a logical fallacy.

For the record, I don't see how it's possible either. To really see it, we would have to find a more fundamental theory from which QM can be derived.

 

[IcedEcliptic]

No. What is very obviously absurd is that an ape-like creature that historically has just descended from the trees, actually thinks that reality MUST conform to his/her prejudice and intuition. I don't think that nature, the world, reality, or call it whatever, cares about how you want the world to be. In a wider context, everything is absurd - how reality works is absurd, existence is absurd, life is absurd, self-awareness is absurd, but it's a brute fact. Face it or suggest a reason why it must NOT be absurd.

It must all be stemming from the fact that we thought for so long that we understood reality and existence. We do not, and this is exactly 100.00% certain. We have no proper understanding of what is going on, how it is going on and why it is going on. We are still dumb animals born in a fairly absurd reality. Face this fact, or join the religious who think they have the important answers figured out.

Fredrik beat me to this, but I will say that you keep the "dumb animal" part, and that may be true. Perhaps the universe is comprehensible to a dumb animal, you are not dealing in logic, just virulent personal bias. The real Cantor would be appalled.

 

[GeorgCantor]

Fredrik beat me to this, but I will say that you keep the "dumb animal" part, and that may be true. Perhaps the universe is comprehensible to a dumb animal, you are not dealing in logic, just virulent personal bias. The real Cantor would be appalled.

No. He has not beat you to it. You clearly did not understand what he said and what he had meant to say with his previous posts, considering his last post. If you have nothing better than an ad hominem, i am not intersted in contunuing this discussion with you.

 

[GeorgCantor]

A fictional universe with the property that a description of some aspect of it resembles a description of the real universe.

If the fictional universe becomes real according to the rules and predictions of qm, then the fictional universe is our universe and it is described by QM. I.e. QM describes the world "out there".

We have to be logical and logic dictates that if said theory makes correct predictions(so far QM is the most successful theory there is in physics), then it must describe reality.

That conclusion does not follow from that premise.

It doesn't? Why?

I think this reveals what your mistake is. You're making an "argument from incredulity". You don't see how what I'm suggesting is possible, so it must be impossible. That's not a logical argument, it's a logical fallacy.

For the record, I don't see how it's possible either. To really see it, we would have to find a more fundamental theory from which QM can be derived.

OK, one could be faithful that QM doesn't describe reality for fear or anxiety. But the fact that it has made the most successful and tested predictions in science means something very disturbing - that it is very likely the right description of reality. I still fail to see how one would justify a world different than the one 'projected' by qm, yet conforming to the experiments like DCE, the c60 molecules in the twin slit, observed superpositions, etc.

 

[IcedEcliptic]

No. He has not beat you to it. You clearly did not understand what he said and what he had meant to say with his previous posts, considering his last post. If you have nothing better than an ad hominem, i am not intersted in contunuing this discussion with you.

What discussion? You're relying on nonscientific reasoning to reach conclusions. There is nothing to discuss except the flaws in your reasoning. Your personal prejudices and views, intuition as Frederik has said, is what you rely on here. That's just not useful in this context.

 

[GeorgCantor]

What discussion? You're relying on nonscientific reasoning to reach conclusions. There is nothing to discuss except the flaws in your reasoning. Your personal prejudices and views, intuition as Frederik has said, is what you rely on here. That's just not useful in this context.

What prejudice? Please site the post that exposes my prejudices, as i claim I have no answers to philosophical questions. You never even made a statement so far, apart for the cryptic incoherent "That's absurd" reply to my post:

Any formalism that makes stunningly correct predictions about the world out there must be describing the world out there. Proposing otherwise is probably not even logically consistent.

And yes, it is a discussion even if you don't understand what is being discussed. The argument that QM doesn't describe reality isn't a new one, though i have not seen it being discussed here.

Further, what "nonscientific reasoning to reach conclusions" am i using? I claim that you don't understand at least 90% of what is being discussed here, so what's the point of your participation? Do you even understand that science is silent as to what happens to quantum systems between measurements? What science exactly do you have in mind? That of your fantasy or that of your personal philosophy?

Your personal prejudices and views, intuition as Frederik has said, is what you rely on here.

Fredrik DOESN'T KNOW how reality could be, if QM isn't a true description of it. But he is hopeful that it will be understood(one day). Do you understand as much?

 

[IcedEcliptic]

What prejudice? Please site the post that exposes my prejudices, as i claim I have no answers to philosophical questions. You never even made a statement so far, apart for the cryptic incoherent "That's absurd" reply to my post:




And yes, it is a discussion even if you don't understand what is being discussed. The argument that QM doesn't describe reality isn't a new one, though i have not seen it being discussed here.

Further, what "nonscientific reasoning to reach conclusions" am i using? I claim that you don't understand at least 90% of what is being discussed here, so what's the point of your participation? Do you even understand that science is silent as to what happens to quantum systems between measurements? What science exactly do you have in mind? That of your fantasy or that of your personal philosophy?





Fredrik DOESN'T KNOW how reality could be, if QM isn't a true description of it. But he is hopeful that it will be understood(one day). Do you understand as much?

Here is what I understand: The formalism of QM is a tool for making meaningful predictions, and not a complete theory. While it may describe some elements of reality, it is incomplete. This is hardly a stretch. I have seen it argued many times that QM is a series of mathematical tools, and not an ontology, if you have not, you have not been reading other people's posts.

For your prejudice, I would point to the monkeys in trees bit. I have no notion as to whether reality, if there is such a thing, can be understood. Perhaps human beings are perfectly capable of doing so, unlikely as that seems. Your prejudice is that reality must be of a nature and complexity that evolved apes cannot describe or understand that. It is not a bad assumption, but it is still just that, an assumption.

You also keep going on about how "dumb" we are as a species, so I'll ask you: compared to what? Arguing for the "What fools these mortals be." angle is rhetorical and biased, and you belabor it beyond all reason, as Frederik has already pointed out, thus "beating me to it" as I said earlier.

Frederik isn't certain as to the nature of reality, except that he personally believes in some limits (MWI for instance), but you are certain of its incomprehensibility. Why!? Where have you found evidence in our short history (which you keep referrring to) which proves your point? The fact that people once thought that the world was flat, did not stop the eventual understanding that it is spheroid. That understanding does not stop us from appreciating the possibility of a holographic principle, or some other deeper description either.

Arguing that past ignorance predicts a future of ignorance may be a likely thing, but it is not the biblical certainty that you present it as. For the "90%" comment, I assume that is a joke about statistical certainty, and not a baseless statement you have no hope of confirming.

Any formalism that makes stunningly correct predictions about the world out there must be describing the world out there. Proposing otherwise is probably not even logically consistent.

That is ABSURD, and not logical. QM makes stunningly correct predictions which have not been sufficiently tested to lead to the conclusion that it is a description of nature. In fact, that notion is on conflict with your argument of perpetual stupidity of people. Further, GR is a formalism that makes stunningly correct predictions which eventually break down and clash with QM, and visa versa. Which "stunningly correct" set of predictions is correct? This would seem to indicate that we are dealing in partial descriptions to accommodate our, how would you enjoy it, "monkey brains". There may be no need for non standard QM interpretations, but the fact is that they arose because of a conflict with the nature we predict and the nature we routinely observe.

It is not logically absurd, although I do not believe it, to conclude that all probabilities are expressed, and no collapse occurs. Your refutation is a bit of an ad hominem attack against, well, Hominids. My guess is that you are quite religious, and not well versed with the day to day workings of QM as applied by engineers and physicists doing work. It is only a guess, I may be wrong, and by your "reasoning" I only have about 10% to work with!

 

[Jimmy Snyder]

Any formalism that makes stunningly correct predictions about the world out there must be describing the world out there. Proposing otherwise is probably not even logically consistent.

But classical physics made stunningly correct predictions for 200 years. It turned out that the equations were excellent approximations in limited circumstances while the theoretical underpinnings were simply wrong.

 

[GeorgCantor]

But classical physics made stunningly correct predictions for 200 years. It turned out that the equations were excellent approximations in limited circumstances while the theoretical underpinnings were simply wrong.

Yet, classical physics was a partial description of reality. Quantum physics, according to most physicists, is a better description of reality(in the sense of 'truer' description of reality). Although it may be incomplete, it's hardly possible to call it a wrong description of reality or that it's NOT a description of reality(I still fail to see how an experimentally verified theory could be a wrong description of reality). Of course it is a better and fuller, though incomplete, description of reality. Is somebody arguing that point?

 

[magpies]

I can if you want me too?

 

[GeorgCantor]

I can if you want me too?

Yes, experiments that confirm thousands of times the formalism of QM are wrong and your ape-like intuition is right. Keep it coming.

 

[magpies]

Well the main problem I see with QM and any other theory is that none of them actually explain what "stuff" is made out of. You can say it's made out of electrons or particles or wood ect... But it will always leave you wondering what is that made out of... It may be an unanswerable question really. Because how do we define substance without using substance it's self? So this is really what QM or any other theory is trying to answer the question of the chicken and the egg clearly. I suppose the answer to what stuff is may exist however I highly doubt we will ever find it.

I would be willing to bet that it is in our nature to not find this answer and for it to be found will take a different type of being. I would guess that most humans would think that our children either in the form of actual children or some type of AI would be able to find it. However I'm thinking it will take a completely different type of mind to solve these problems and that mind either already exists or will at some point or will never. Most likely it does not exist and by what means it will come into existence I can not really think of. I suppose when this being does come into existence the world will never be the same.

 

[Jimmy Snyder]

Yet, classical physics was a partial description of reality.

What does classical physics get even partially right? As I understand it, the equations are slightly wrong in all circumstances and wildly wrong in some. But more to the point, the theoretical basis is incorrect.

 

[Fredrik]

If the fictional universe becomes real according to the rules and predictions of qm, then the fictional universe is our universe and it is described by QM. I.e. QM describes the world "out there".

Indirectly yes, but I don't think it's appropriate to say that "the theory describes reality" if this is the case. That phrase should be reserved for situations when the theory describes only the relevant aspects of our universe, and not for situations when it describes a much larger system that may or may not exist.

It doesn't? Why?

You're the one who says that it does, so the burden of proof is on you.

OK, one could be faithful that QM doesn't describe reality for fear or anxiety.

No fear or anxiety is needed to admit that the possibility exists. A healthy respect for logic is sufficient.

 

[Fredrik]

What does classical physics get even partially right?

Orbits of planets, that if you drop an apple it falls to the ground, that a current through a wire will produce a magnetic field, that a gas cools when it expands, time dilation, the expansion of the universe, ... We could probably fill a book just with the examples.

 

[Jimmy Snyder]

Orbits of planets, that if you drop an apple it falls to the ground, that a current through a wire will produce a magnetic field, that a gas cools when it expands, time dilation, the expansion of the universe, ... We could probably fill a book just with the examples.

Orbits of planets - classical mechanics gets the wrong orbits. The case of the planet Mercury around the sun is a famous example.

That if you drop an apple it falls to the ground - classical mechanics gives the wrong trajectory.

That a current through a wire will produce a magnetic field - it gets it wrong for the current associated with the orbit of an electron in an atom, qualitatively as well as quantitatively.

that a gas cools when it expands - gets the wrong equation because the rate of expansion is frame dependent.

time dilation - no, it failed to predict that.

the expansion of the universe - no, it failed to predict that.

We could probably fill a book just with the examples. - that's my point. There was a time when they did fill books with the examples because the predictions were "stunningly correct".

 

[IcedEcliptic]

Well, it would seem GeorgCantor's diversion worked relatively well. Meanwhile, I still note "ape-like intuition" and have a hearty chuckle. How have we come to this given the OP?

 

[GeorgCantor]

Well, it would seem GeorgCantor's diversion worked relatively well. Meanwhile, I still note "ape-like intuition" and have a hearty chuckle. How have we come to this given the OP?

I'd say that the moment i stopped responding to your mischaracterizations of my posts, the discussion got back on topic - What it is that QM describes and why nobody seems to understand it. But nice try anyway.

 

[GeorgCantor]

What does classical physics get even partially right? As I understand it, the equations are slightly wrong in all circumstances and wildly wrong in some. But more to the point, the theoretical basis is incorrect.

We get better approximations and we are definitely getting more accurate answers. We built internal combustion engines and airplanes without the aid of GR and QM. In certain 'everyday' domains, classical physics is still a perfectly valid tool. F=m.a is still as good as it gets within the same referrential frame. With better approximations and better theories, we get a better understanding of what reality is. Now if everything we have built as a model of how reality works is wrong, then yes, you might say that we are chasing a red herring, but as far as i know, there is no better way to understand reality than through physics.

We now know, through the aid of quantum physics, that matter is not made of balls but of entities that are neither particles nor waves in the classical sense. Whatever it is that an electron really is prior to interaction/measurement/decoherence, we now have a better and truer knowledge of reality. Agree?

Even if we are living in the Matrix, classical physics has a valid domain to fill in, and it's definitely a good approximation for mundane 'everyday' purposes.

 

[waht]

QM is a non-relativistic quantum theory.

QFT (Quantum Field Theory) is a relativistic quantum theory that explains three of the fundamental forces with stunning accuracy, and it could explain gravity all in one shot but we are getting lots of infinities in the equations.

QFT eventually breaks downs at very hight energies, but within its range of operation it's the most accurate theory yet, with predictions verified to more than 9 decimal places.

The cool part is QFT can be easily simplified to QM if needed.

 

[GeorgCantor]

Indirectly yes, but I don't think it's appropriate to say that "the theory describes reality" if this is the case. That phrase should be reserved for situations when the theory describes only the relevant aspects of our universe, and not for situations when it describes a much larger system that may or may not exist.

I agree with this, what i meant to say was that QM is likely an incomplete model of reality but not a wrong one. Confusing as it is, it's still a far better glimpse at what reality is, than classical physics.

No fear or anxiety is needed to admit that the possibility exists. A healthy respect for logic is sufficient.

The possibility exists, i'll concede that. But given our previous experience from Newtonian and relativity physics, we have good arguments to believe that qm is actually describing reality(or at least aspects of it). It is a far more interesting avenue to explore, given the philosophical inclination of the participants here, and a far more promising one. Classical physics is at a dead-end on most of the questions asked in the philosophy forum.

 

[GeorgCantor]

QM is a non-relativistic quantum theory.

QFT (Quantum Field Theory) is a relativistic quantum theory that explains three of the fundamental forces with stunning accuracy, and it could explain gravity all in one shot but we are getting lots of infinities in the equations.

QFT eventually breaks downs at very hight energies, but within its range of operation it's the most accurate theory yet, with predictions verified to more than 9 decimal places.

The cool part is QFT can be easily simplified to QM if needed.

Yes but what do you make of it all? Is this how reality is, based on the fact that qft 'explains three of the fundamental forces with stunning accuracy'. The only ontology, as far as i am aware, consistent with qft is the Relational Block Universe, which i take to be a case for a virtual world.

 

[Jimmy Snyder]

Agree?

You seem to be of two minds. On the one hand you agree that the model might be a red herring. Yet on the other hand, you claim that it brings us a truer knowledge of reality. How can I agree with that? We were bitten once by a stunningly good model, what makes you think it won't happen again?

 

[Fredrik]

Orbits of planets - classical mechanics gets the wrong orbits. The case of the planet Mercury around the sun is a famous example.

That if you drop an apple it falls to the ground - classical mechanics gives the wrong trajectory.

That a current through a wire will produce a magnetic field - it gets it wrong for the current associated with the orbit of an electron in an atom, qualitatively as well as quantitatively.

that a gas cools when it expands - gets the wrong equation because the rate of expansion is frame dependent.

time dilation - no, it failed to predict that.

the expansion of the universe - no, it failed to predict that.

We could probably fill a book just with the examples. - that's my point. There was a time when they did fill books with the examples because the predictions were "stunningly correct".

It's pretty frustrating to get this type of reply. First of all, you're clearly answering as if my post had been a reply to a different question than the one you actually asked. You need to go back and look at what I actually replied to. You asked "What does classical physics get even partially right?", so what you're saying now sounds like complete crazy talk to those of us who remember that. I'm sure you didn't intend to suggest that orbits are nothing at all like ellipses, but that's what you did.

Second, you're wrong about several of these things, regardless of what you think you're replying to. For example, time dilation is a prediction of special relativity, and special relativity is a classical theory.

Third, it's clear both from this post and your previous one that you think it's meaningful to label theories as either "right" or "wrong". It's not. They're all wrong. Some are just less wrong than others, and those are the ones we consider "good".

 

[waht]

Yes but what do you make of it all?

Is this how reality is, based on the fact that qft 'explains three of the fundamental forces with stunning accuracy'.

The definition of a "theory" in science loosely consists of two parts. The first part of a theory is a set of facts, evidence, and experimental data. And the second part is deductive explanation and analysis of that data.

A "theory" doesn't claim what reality is.

Theories like Classical Physics, GR, QM, QFT, are deductive explanations of empirical evidence that work up to a certain limit. That's all.

 

[Jimmy Snyder]

It's pretty frustrating to get this type of reply. First of all, you're clearly answering as if my post had been a reply to a different question than the one you actually asked. You need to go back and look at what I actually replied to. You asked "What does classical physics get even partially right?", so what you're saying now sounds like complete crazy talk to those of us who remember that. I'm sure you didn't intend to suggest that orbits are nothing at all like ellipses, but that's what you did.

Second, you're wrong about several of these things, regardless of what you think you're replying to. For example, time dilation is a prediction of special relativity, and special relativity is a classical theory.

Third, it's clear both from this post and your previous one that you think it's meaningful to label theories as either "right" or "wrong". It's not. They're all wrong. Some are just less wrong than others, and those are the ones we consider "good".

I think all theories are wrong. I am curious to have you identify what made you think I didn't.

There is an issue of vocabulary which I got wrong. When I said classical physics, I meant pre-1900 physics. This was an error which may have mislead people as to my meaning. This is why post-1905 predictions were in your post. I apologize for that. However, the problem with the orbit of Mercury was known before 1900.

I have answered all posts in the context of GeorgeCantor's post. Anyone who replied to my posts out of that context was probably surprised and dismayed when instead of interpretting their words as they meant them, I interpretted them within that context. Read Georg's post to see what my issue is. If you are not posting to that issue, then your post may well be misinterpretted.

My attitude toward science is that it gives us tentative theories that are good pending the next experiment. All that truth and reality stuff belongs in a philosophy or religion forum.

 

[Fredrik]

But given our previous experience from Newtonian and relativity physics, we have good arguments to believe that qm is actually describing reality(or at least aspects of it).

That...sounds like a prejudice.

It is a far more interesting avenue to explore, given the philosophical inclination of the participants here, and a far more promising one. Classical physics is at a dead-end on most of the questions asked in the philosophy forum.

I find it a bit odd that you seem to think of classical physics as the alternative. A person who believes that QM doesn't describe reality (or rather that the system it describes is much larger than anything that "actually exists") isn't automatically going to want to go back to classical physics.

Personally, I think it's definitely worthwhile to study the consequences of the assumption that QM describes an actual physical system. I also think there's lots of work that remains to be done in that area, because most of the work that's been done on "the" MWI has been based on the misguided idea that the Born rule can be dropped from the theory and derived from first principles.

A lot of people think it would be a complete waste of time to study the consequences of the assumption that QM describes reality, since it doesn't change the predictions of the theory. I think they're a little naive. Even if the assumption is wrong, we could learn a new way to think about QM that might even turn out to be useful when doing calculations.

I disagree with your reasons to think that QM describes reality, but I think there's a reasonable chance that QM with this extra assumption can be combined with anthropic arguments to explain a lot of things that "just QM" can't. I'm thinking of questions like, "why is there such a thing as time?" or "why did the universe start out in a low entropy state?" (No, I don't have the answers...at least not yet ).

 

[Fredrik]

I think all theories are wrong. I am curious to have you identify what made you think I didn't.

I expressed myself poorly there. What I should have said is that you seemed to think that a theory being "wrong" is a bad thing, but maybe I was wrong about that.

My attitude toward science is that it gives us tentative theories that are good pending the next experiment.

My attitude is that Newton's theory of gravity is still an excellent theory more than a century after the first inaccuracies in its predictions were discovered, and almost a century after a much better theory was found. To call these theories "tentative" makes it sound like we're keeping our fingers crossed hoping that "this one will be correct", and that we should be disappointed about our failure when we find a situation where its predictions are clearly wrong.

 

[Jimmy Snyder]

To call these theories "tentative" makes it sound like we're keeping our fingers crossed hoping that "this one will be correct", and that we should be disappointed about our failure when we find a situation where its predictions are clearly wrong.

OK, as long as you realize that you said all that, not me. I'll be out there dancing a jig and saying "told you so, told you so".

 

[IcedEcliptic]

I'd say that the moment i stopped responding to your mischaracterizations of my posts, the discussion got back on topic - What it is that QM describes and why nobody seems to understand it. But nice try anyway.

Right, and yet you're still suffering from a flux of the mouth. All you have is a rigid outlook and bombast. Boring.