story time :Quantum physics, like something out of a sci-fi movie, intriguing

[TappingTheZen]

Sorry, I mean brofessor. Brofessing quantonium physics

Brofessor of quantum phys-lifts

[BraddlesMcGee]

Well, actually, "Being in superposition" is not an objective property of a quantum mechanical state. Quantum mechanical states live in a Hilbert space, where, since it is a vector space, every state can be expressed as the sum of other states. That is what we mean by "superposition": The sum of two states is a again a state.

But as long as you don't choose a basis of this vector space as your reference for what an "unsuperposed" state is, asking whether a state is "in superposition" doesn't make any sense. A state of definite position is not a superposition of other states of definite position, but it is an infinite superposition of states of definite momentum. Every state is a superposition of states that belong to a basis where it itself isn't a basis vector.

So "quantum superposition" is not some sort isolated postulate of quantum mechanics, it is built right into the basic mathematical structure of the space of states. You cannot remove "superposition" from this formulation of the theory any more than you can remove real numbers from classical mechanics. So there is no experimental test like "Quantum mechanics with superposition" vs. "Quantum mechanics without superposition" where you could compare the predictions of two well-defined theories.

Also, note that this superposition really is about a technical property in the mathematical formalism: Our ability to form sums of states. The formalism itself makes no direct claim about how you should think about this, and indeed different quantum interpretations may disagree whether "the object is in both states at once" is really the correct natural language interpretation of the mathematical fact in the formalism. But since (most) quantum interpretations do not change the experimental predictions of quantum mechanics, none of these different ontologies of quantum superposition can be experimentally tested.

Therefore, every experimental test of quantum mechanics is an experimental test of "quantum superposition", if you so wish. The notion of superposition cannot be separated from the rest of quantum mechanics, it is too fundamental for that. Whether that "really means" an object "is in two states at the same time" is not a question physics can answer.

[TappingTheZen]

Well, actually, "Being in superposition" is not an objective property of a quantum mechanical state. Quantum mechanical states live in a Hilbert space, where, since it is a vector space, every state can be expressed as the sum of other states. That is what we mean by "superposition": The sum of two states is a again a state.

But as long as you don't choose a basis of this vector space as your reference for what an "unsuperposed" state is, asking whether a state is "in superposition" doesn't make any sense. A state of definite position is not a superposition of other states of definite position, but it is an infinite superposition of states of definite momentum. Every state is a superposition of states that belong to a basis where it itself isn't a basis vector.

So "quantum superposition" is not some sort isolated postulate of quantum mechanics, it is built right into the basic mathematical structure of the space of states. You cannot remove "superposition" from this formulation of the theory any more than you can remove real numbers from classical mechanics. So there is no experimental test like "Quantum mechanics with superposition" vs. "Quantum mechanics without superposition" where you could compare the predictions of two well-defined theories.

Also, note that this superposition really is about a technical property in the mathematical formalism: Our ability to form sums of states. The formalism itself makes no direct claim about how you should think about this, and indeed different quantum interpretations may disagree whether "the object is in both states at once" is really the correct natural language interpretation of the mathematical fact in the formalism. But since (most) quantum interpretations do not change the experimental predictions of quantum mechanics, none of these different ontologies of quantum superposition can be experimentally tested.

Therefore, every experimental test of quantum mechanics is an experimental test of "quantum superposition", if you so wish. The notion of superposition cannot be separated from the rest of quantum mechanics, it is too fundamental for that. Whether that "really means" an object "is in two states at the same time" is not a question physics can answer.

This is fair and a really solid post (perhaps too nuanced for the misc tho), but of course i was trying to use language for the misc, and the misc are unlikely to have a strong grasp of concepts like hilbert space, or the fact that the superposition is the sum of states (and what this 'means' outside of an abstract mathematical structure is down to the interpretation), and i am generally ignorant to the state of knowledge of the person i'm responding to.

My central point is that your coin analogy in your prior post didn't account for bells theorem, which is where the manifest 'weirdness' of entanglement is expressed

[sqal]

This is the one scientific area that I could never wrap my head around. The so called experts in the field are like "I don't even expect it to behave like this." Yet we have technology that uses this field? I don't understand that at all.

[chalup]

The one thing that REALLY blows my mind is nothing is actually SOLID, its particles vibrating on a certain frequency. There is a chance that any solid object COULD become completely "liquid" or passable. As in we could theoretically walk through walls if all the particles behaved a certain way.

[batmanman]

quantum entanglement is nonsense

you can tell because despite like 50 years of research, quantum computers have never evolved past "2+2=4"

brb make pair of gloves in a factory, put each one in a box and drive one box 200 miles away

"yooo I got the right hand glove, let me call my good friend back at the factory and see what he got!"

"OMG NO WAY! YOU GOT THE LEFT HAND GLOVE! WoooOoooOOOOOo sooo spoooky! omg they're definitely connected!"

"we did some bullshiit trigonometry and determined that they affect eachother AFTER we opened the boxes and not when we made them as a pair in the factory"

"uhhh ermmmm, no, if we have a tailor change the left hand glove into a right hand glove it doesn't change the right hand glove into a left.... STOP ASKING QUESTIONS!!!"

[sqal]

The one thing that REALLY blows my mind is nothing is actually SOLID, its particles vibrating on a certain frequency. There is a chance that any solid object COULD become completely "liquid" or passable. As in we could theoretically walk through walls if all the particles behaved a certain way.

[chalup]

Well, actually, "Being in superposition" is not an objective property of a quantum mechanical state. Quantum mechanical states live in a Hilbert space, where, since it is a vector space, every state can be expressed as the sum of other states. That is what we mean by "superposition": The sum of two states is a again a state.

But as long as you don't choose a basis of this vector space as your reference for what an "unsuperposed" state is, asking whether a state is "in superposition" doesn't make any sense. A state of definite position is not a superposition of other states of definite position, but it is an infinite superposition of states of definite momentum. Every state is a superposition of states that belong to a basis where it itself isn't a basis vector.

So "quantum superposition" is not some sort isolated postulate of quantum mechanics, it is built right into the basic mathematical structure of the space of states. You cannot remove "superposition" from this formulation of the theory any more than you can remove real numbers from classical mechanics. So there is no experimental test like "Quantum mechanics with superposition" vs. "Quantum mechanics without superposition" where you could compare the predictions of two well-defined theories.

Also, note that this superposition really is about a technical property in the mathematical formalism: Our ability to form sums of states. The formalism itself makes no direct claim about how you should think about this, and indeed different quantum interpretations may disagree whether "the object is in both states at once" is really the correct natural language interpretation of the mathematical fact in the formalism. But since (most) quantum interpretations do not change the experimental predictions of quantum mechanics, none of these different ontologies of quantum superposition can be experimentally tested.

Therefore, every experimental test of quantum mechanics is an experimental test of "quantum superposition", if you so wish. The notion of superposition cannot be separated from the rest of quantum mechanics, it is too fundamental for that. Whether that "really means" an object "is in two states at the same time" is not a question physics can answer.

I'm a decently smart person and this post makes absolutely no sense to me. It's borderline "we have no idea how things exist on X level, so here is word salad to make us look smart"

and I say this knowing they know what they are talking about but its so over my head its not even worth trying to understand.

[BraddlesMcGee]

This is fair and a really solid post (perhaps too nuanced for the misc tho), but of course i was trying to use language for the misc, and the misc are unlikely to have a strong grasp of concepts like hilbert space, or the fact that the superposition is the sum of states, and i am generally ignorant to the state of knowledge of the person i'm responding to.

My central point is that your coin analogy in your prior post didn't account for bells theorem, which is where the manifest 'weirdness' of entanglement is expressed

OK I confess, I plagiarized from here

https://physics.stackexchange.com/qu...ion-do-we-have

If it's good enough for Harvard deans it should pass here on the misc.

But it's a different reply lower down I wish to quote now

The answers to your questions are immediate consequences of the definition of a quantum state.

1. Every quantum state is a superposition for the same reason that every integer is a sum of other integers. One could try to test this empirically by checking that 8=3+5 and then that 9=2+7 and then that 10=(-3)+13, but to do that would be entirely to miss the point. The result is an immediate consequence of the definitions, and it would be pointless to "test" it in this way.

2. "I would like to know if objects of our world can be in two states at the same time." No they can't, for exactly the same reason that a bachelor cannot be married. Once again, this is a direct consequence of the definition and it would be pointless to test. (And this, incidentally, has pretty much nothing to do with quantum mechanics in particular; it has only to do with the broad general meaning of the word "state".)

"The result is an immediate consequence of the definitions"

i.e. that's how it's modeled.

[BraddlesMcGee]

I'm a decently smart person and this post makes absolutely no sense to me. It's borderline "we have no idea how things exist on X level, so here is word salad to make us look smart"

and I say this knowing they know what they are talking about but its so over my head its not even worth trying to understand.

See above.

[TappingTheZen]

OK I confess, I plagiarized from here

https://physics.stackexchange.com/qu...ion-do-we-have

If it's good enough for Harvard deans it should pass here on the misc.

But it's a different reply lower down I wish to quote now



"The result is an immediate consequence of the definitions"

i.e. that's how it's modeled.

lol fair enough re plagerism.

Yes, you're quite right that a large part of it is formalism and a lot of the layman confusion and mysticism around quantum mechanics is really a matter of formalism, but this post still seems to be missing the result of bells theorem and is heavily focussed on the formalism of superposition; this is where i suggest you look.

Bells theorem, and the experimental results show us that something weird (and by weird i mean non-classical) is going on with entanglement, beyond just mere formalism, as i've explained in prior posts in this thread, and also posted a video explaining (perhaps i'm poor at explaining myself in which case it would be a waste of time to try to explain the signifiance of bells theorem again, but there's tons of material out there on bells theorem, so i'll just define it and if anyone wishes to watch the video i posted or research themselves they can).

Essentially, bells theorem tells us that a local hidden variable theory is not sufficient to explain the correlations between entangled particles, and thus we have to give up locality (or change something more fundamental, like the many worlds interpretation and the whole 'many worlds' ontology that comes along with it).

[georgeenoob]

They're linked, meaning connected, so when one particle is altered, the change affects the other particle.

Stopped reading here. Dafuq are you even talking about. I'd rather be a dumbass than read more of this sht.

[georgeenoob]

and I say this knowing they know what they are talking about but its so over my head its not even worth trying to understand.

Wizard

[georgeenoob]

The one thing that REALLY blows my mind is nothing is actually SOLID, its particles vibrating on a certain frequency. There is a chance that any solid object COULD become completely "liquid" or passable. As in we could theoretically walk through walls if all the particles behaved a certain way.

Fuark should've stopped reading.

They are solid wtf.

[chalup]

OK I confess, I plagiarized from here

https://physics.stackexchange.com/qu...ion-do-we-have

If it's good enough for Harvard deans it should pass here on the misc.

But it's a different reply lower down I wish to quote now



"The result is an immediate consequence of the definitions"

i.e. that's how it's modeled.

See above.

This makes way more sense and dumbs it down pretty good.

[dingler]

B

this is straight from the department of energy

I work with the DOE a lot. Just because they say something doesn’t mean it’s true. They do help develop a lot of cool chit though.