A Question for Cjlr
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18-09-2015, 02:49 PM
RE: A Question for Cjlr
(18-09-2015 02:40 PM)The Organic Chemist Wrote:  You are saying that your internet education is better than an academic one. Wikipedia is helpful but laughable as a concrete reference.

I am saying that internet has closed the gap between the expert and a "layman" to the point where the "layman" can challenge someone claiming to be an expert.
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18-09-2015, 02:56 PM
RE: A Question for Cjlr
(18-09-2015 02:39 PM)cjlr Wrote:  You still don't understand the difference between spin and angular momentum, nor the difference between quantum objects and classical mechanics.

So no, even though I admit to an overly broad phrasing - in the hope of getting through to you, since your "understanding" is entirely predicated on sloppy and inadequate analogies to intuitive classical behaviour! - I do not agree that any contradiction was given.

I understand classical spin. Classical spin is rotation around an axis that runs through the center of an object. Angular Momentum is the amount of that rotation.

I do not understand what spin is in the quantum sense which is why I was more than willing to concede to you when you said a 4d electron could not have 2 spins. I wasn't going to challenge you on it and still haven't.

I have only challenged you in this thread on classical level.
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18-09-2015, 03:09 PM
RE: A Question for Cjlr
(18-09-2015 02:43 PM)Heywood Jahblome Wrote:  ZoraPrime. Cjlr made this claim, "the electron quite literally cannot have simultaneously well-defined spin in multiple axes". We all agree that in 3d space an object cannot have simultaneously well-defined spin in multiple axes". In 4d space can an object have well defined spin in multiple axes?

Your question proves that you don't understand what you're asking.
(not that the original one didn't...)

An electron already has spin in multiple axes: x, y, and z. I don't think you understand the difference between spin, the quantum property of an object, and a spin state, in which that object exists (or, you know, Fermions versus Bosons, or indeed any real quantum mechanics whatsoever - but that's beside the point). An electron cannot have two spins any more than it can have two masses. When I say they cannot be simultaneously well-defined I am referring to the consequences of the operators being non-commuting. This leads to an uncertainty relation, which was the original germ of this pointless discussion - you don't like uncertainty and are trying to find a way around it.

If we assume instead that there are four space-like dimensions - and keeping everything else the same - then an electron would have spin in multiple axes: w, x, y, and z. The operators would still be non-commuting. Of course, this is pointless, because it's not reality.

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18-09-2015, 03:15 PM
RE: A Question for Cjlr
(18-09-2015 02:56 PM)Heywood Jahblome Wrote:  I understand classical spin. Classical spin is rotation around an axis that runs through the center of an object. Angular Momentum is the amount of that rotation.

I do not understand what spin is in the quantum sense which is why I was more than willing to concede to you when you said a 4d electron could not have 2 spins. I wasn't going to challenge you on it and still haven't.

I have only challenged you in this thread on classical level.

Your OP referred to - and here you again refer to - electrons. But, electrons are not classical. They do not possess classical properties. They do not obey classical rules.

And in any case what you think I'm "conceding" by deferring to ZoraPrime's more detailed explanation of 4D generalisations is still not what you originally claimed.
(if you're going to be stubborn about disk versus hyperdisk, you really ought to be very clear when you're talking about hyperspin as opposed to spin...)

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18-09-2015, 03:28 PM
RE: A Question for Cjlr
(18-09-2015 02:56 PM)Heywood Jahblome Wrote:  I understand classical spin. Classical spin is rotation around an axis that runs through the center of an object. Angular Momentum is the amount of that rotation.

I do not understand what spin is in the quantum sense which is why I was more than willing to concede to you when you said a 4d electron could not have 2 spins. I wasn't going to challenge you on it and still haven't.

I have only challenged you in this thread on classical level.

I am sure you do understand classical spin. You however, just showed your ignorance completely. THIS is why your wikipedia education is worth as much as your forgiveness.

"If we are honest—and scientists have to be—we must admit that religion is a jumble of false assertions, with no basis in reality.
The very idea of God is a product of the human imagination."
- Paul Dirac
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18-09-2015, 03:39 PM
RE: A Question for Cjlr
(18-09-2015 02:44 PM)cjlr Wrote:  
(18-09-2015 02:40 PM)The Organic Chemist Wrote:  I will repeat what I said: show mathematically that they are mistaken or STFU. Or show the math and still STFU.

He's reduced to harping on a bad choice of wording in my earlier statement(s), because that's all he's able to address. Don't hold your breath.

I didn't expect him to respond. If he had that kind of mathematical and scientific accumen, he would realize that what he is trying to do is silly.

"If we are honest—and scientists have to be—we must admit that religion is a jumble of false assertions, with no basis in reality.
The very idea of God is a product of the human imagination."
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18-09-2015, 06:56 PM
RE: A Question for Cjlr
this thread took a whole other turn towards stupid while I was out.

(18-09-2015 02:15 PM)Heywood Jahblome Wrote:  I am glad you are finally conceding that in a 4D space a dust cloud would not collapse into a disc.

The only reason why there was contention on this point is because you were arguing the semantics of what a "disc" means. No one conceded anything (other than perhaps the word "disc" is ambiguous); rather, we just caught on that you were getting hung up on semantics and had to clarify.

(18-09-2015 02:28 PM)Heywood Jahblome Wrote:  The nice thing about the internet is you don't have to take the word of someone who claims to be an expert. You can spend a few minutes and do some research on your own to see if what they are claiming makes sense.

Here is how the conversation went:

Heywood: "Cjlr, I have a question for you, would a 4d electron have two spins?"
Cjlr: "no"
Heywood: "Oh...I thought it would because a 4d dust cloud has two spins and would not collapse into a disc....I know electron spin is not the same as classical spin"
Organic Chemist: "The Yellow one....is the Sun!"
Heyood to OC: "Get lost Copernicus"
Cjlr in a condescending tone: "What makes you think that?"
Heywood: "In 4D you would have spin in the XY plane and spin in the WZ plane"
Cjlr: "Well you are wrong, spin occurs around a single axis...that is what spin is"
ZoraPrime: "A 4d dust cloud would collapse into a hyperdisc"
.
.
Cjlr: "Well obviously a 4d dust cloud wouldn't collapse into disc"

1.) That isn't how the conversation went at all.

2.) You're still treating classical angular momentum as analogous to quantum spin, as made clear in your next quote. You *say* that there's a difference, but your entire argument involving accretion disks is so irrelevant to quantum spin that I don't believe for a second you understand what the difference is.

(18-09-2015 02:43 PM)Heywood Jahblome Wrote:  I don't always re-read a post after I have read it. Here is a direct question for ZoraPrime.

ZoraPrime. Cjlr made this claim, "the electron quite literally cannot have simultaneously well-defined spin in multiple axes". We all agree that in 3d space an object cannot have simultaneously well-defined spin in multiple axes". In 4d space can an object have well defined spin in multiple axes?

Let me make this clear: in classical angular momentum, you can have a well-defined angular momentum along all axes (on in the case of 4D, planes). The fact that an accretion is biased along one axis (call it the z-axis) does not mean the other axes are ill-defined, they just happen to be zero. An accretion disk has a well-defined angular momentum along all axes.

What happens in quantum spin isn't that the z-axis happens to be spin up or spin down while the other two are zero; the other two aren't well-defined. Because of how the mathematics work out, we can make a stronger statement that both the x-axis and y-axis spin are in a superposition of up along x (or) y and down along x (or) y with equal probability of finding them along each one.

Just to make this argument end, I went ahead and took the unfortunate task of computing the damn commutator (i'm ignoring iћ, it's an annoying constant that doesn't change the main result). In the end, you have non-zero terms that remain even if you're talking about orthogonal planes. I honestly think you're going to open up the work, think it's alphabet soup, and never look at it again. The point is, even in higher Euclidean dimensions, the spin operators do not commute. Work here.

Unless I made arithmetic errors (which anyone is welcome to check) that commutation relationship basically ends this discussion.
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18-09-2015, 07:40 PM (This post was last modified: 18-09-2015 07:46 PM by Heywood Jahblome.)
RE: A Question for Cjlr
(18-09-2015 03:15 PM)cjlr Wrote:  
Heywood Jahblome Wrote:I have only challenged you in this thread on classical level.

Your OP referred to - and here you again refer to - electrons. But, electrons are not classical. They do not possess classical properties. They do not obey classical rules.

In post 3 of this very thread I replied to you saying

(11-09-2015 08:20 PM)Heywood Jahblome Wrote:  Your answer is that even if their were 4 spatial dimensions an electron can still only have well defined spin along one axis. Fair enough, I'm not going to dispute you on it.

What part of, "I am not going to dispute you on it" is unclear to you? From post 3 on we are no longer discussing electrons but classical objects. I accepted completely, without any dispute, the answer you gave me regarding electrons. Regarding my question to Zoraprime, I mentioned "electron" because I was quoting you when you were talking about electrons....that is all.
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18-09-2015, 07:59 PM
RE: A Question for Cjlr
(18-09-2015 06:56 PM)ZoraPrime Wrote:  2.) You're still treating classical angular momentum as analogous to quantum spin, as made clear in your next quote. You *say* that there's a difference, but your entire argument involving accretion disks is so irrelevant to quantum spin that I don't believe for a second you understand what the difference is.

Zoraprime, the reason I was so quick to just accept Cjlrs explaination about electrons is because I admint I don't understand quantum spin. I know it concerns angular momentum, but I don't know if it concerns a transformation or not. Seems more like a charge to me.


(18-09-2015 06:56 PM)ZoraPrime Wrote:  Let me make this clear: in classical angular momentum, you can have a well-defined angular momentum along all axes (on in the case of 4D, planes). The fact that an accretion is biased along one axis (call it the z-axis) does not mean the other axes are ill-defined, they just happen to be zero. An accretion disk has a well-defined angular momentum along all axes.

It seems you are contradicting Cjlr who said "Spin refers to angular motion about a single axis. That's how it's defined - it can't be anything else." Can a 4D dust cloud have 2 spins? Yes or no?


(18-09-2015 06:56 PM)ZoraPrime Wrote:  Just to make this argument end, I went ahead and took the unfortunate task of computing the damn commutator (i'm ignoring iћ, it's an annoying constant that doesn't change the main result). In the end, you have non-zero terms that remain even if you're talking about orthogonal planes. I honestly think you're going to open up the work, think it's alphabet soup, and never look at it again. The point is, even in higher Euclidean dimensions, the spin operators do not commute. Work here.

Unless I made arithmetic errors (which anyone is welcome to check) that commutation relationship basically ends this discussion.

It is alphabet soup to me.
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18-09-2015, 08:26 PM (This post was last modified: 18-09-2015 08:32 PM by ZoraPrime.)
RE: A Question for Cjlr
As will become clear in this post, my patience is practically nil at this point because you're spouting off nonsense.

(18-09-2015 07:59 PM)Heywood Jahblome Wrote:  Zoraprime, the reason I was so quick to just accept Cjlrs explaination about electrons is because I admint I don't understand quantum spin. I know it concerns angular momentum, but I don't know if it concerns a transformation or not. Seems more like a charge to me.

cjlr's explanation is correct. Electrons only have spin that is well-defined along one axis.

Quantum spins aren't angular momentum. They aren't really even a type of angular momentum--their more analogous to intrinsic magnetic moment. Very loosely, can be thought of an elementary particle intrisnic angular momentum, but even that explanation isn't quite correct.


Quote:It seems you are contradicting Cjlr who said "Spin refers to angular motion about a single axis. That's how it's defined - it can't be anything else." Can a 4D dust cloud have 2 spins? Yes or no?

I don't even know how to respond to this. Dust clouds don't have spin; only elementary particles do. Dust clouds have angular momentum, which are well-defined in all directions. The fact that accretion disc is confined to one plane has absolutely-fucking-nothing to do with spin. They're different concepts, actually get it through your head already. Cljr, others, and I have been saying this throughout the entire thread, and while you claim (e.g. your previous post to cljr) that you understand the difference, the fact you keep spouting nonsense like "can a dust cloud have 2 spins?" means you actually do not understand the difference.

Of course, since you claim that "The nice thing about the internet is you don't have to take the word of someone who claims to be an expert. You can spend a few minutes and do some research on your own to see if what they are claiming makes sense." i'm sure a few minutes on the internet will clarify the difference. In fact, let me get you started.

Moreover, I didn't contradict cljr for that reason. Spin is defined along one axis. Period. But accretion discs don't have spin because they're macroscopic. cljr have been consistent--when we discuss spins, we use electrons (which are an elementary particle and usually the go-to example for anything quantum); when discussing accretion discs, we use angular momentum.

Quote:It is alphabet soup to me.

It means that spins along different directions don't commute, i.e. spin can only be defined along one direction.
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