Unironically what is spin?

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Anonymous Sun Jan 20 02:37:11 2019 No.10311550 [Reply] [Original]

Unironically what is spin?

>>	Anonymous Sun Jan 20 02:42:53 2019 No.10311559 >>10311550 Intrinsic angular momentum.

>>	Anonymous Sun Jan 20 02:44:07 2019 No.10311561 File: 41 KB, 400x345, inigo-that-word.jpg [View same] [iqdb] [saucenao] [google] >>10311550 >Unironically

>>	Anonymous Sun Jan 20 02:46:08 2019 No.10311565 >>10311550 A number.

>>	Anonymous Sun Jan 20 02:47:21 2019 No.10311570 >>10311550 Spin is the name we give to whatever is the source of the effects we observe in experiments which satisfy all of our expectations of angular momentum except for the lack of rotational motion.

>>	Anonymous Sun Jan 20 02:53:37 2019 No.10311574 >>10311550 A property that particles have, like mass, charge, etc. it has no good macroscopic analogy and it results in a magnetic dipole moment.

>>	Anonymous Sun Jan 20 17:08:28 2019 No.10313201 File: 1.38 MB, 256x256, Belt_Trick.gif [View same] [iqdb] [saucenao] [google] The spacetime component of a field excitation

>>	Anonymous Sun Jan 20 17:23:58 2019 No.10313233 >>10311550 the particle spinning? I never got what was so confusing about this concept.

>>	Anonymous Sun Jan 20 17:26:15 2019 No.10313245 >>10313233 >the particle spinning? But it's not.

>>	Anonymous Sun Jan 20 17:42:02 2019 No.10313314 >>10313245 Do we have the technology to prove it? no. Does that mean it's not? no...

>>	Anonymous Sun Jan 20 17:43:47 2019 No.10313324 >>10313314 What speed is an electron spinning at?

>>	Anonymous Sun Jan 20 17:43:59 2019 No.10313326 >>10313201 https://www.youtube.com/watch?v=AFEX0usTNrU

>>	Anonymous Sun Jan 20 17:45:13 2019 No.10313329 >>10313324 1/2

>>	Anonymous Sun Jan 20 17:46:11 2019 No.10313334 >>10313329 Units?

>>	Anonymous Sun Jan 20 17:47:30 2019 No.10313341 A quantum state of orientation. That's literally it. It's called spin because language is retarded

>>	Anonymous Sun Jan 20 17:48:23 2019 No.10313343 >>10311550 A spinon.

>>	Anonymous Sun Jan 20 17:52:43 2019 No.10313363 >>10313324 (hbar/2)/([mass of an electron]*[displacement of the center of charge from the axis of rotation]^2)

>>	Anonymous Sun Jan 20 17:53:48 2019 No.10313369 >>10313363 So you don't know a number.

>>	Anonymous Sun Jan 20 17:54:29 2019 No.10313373 >>10311550 >Unironically kys

>>	Anonymous Sun Jan 20 17:59:18 2019 No.10313389 >>10313369 correct. problem?

>>	Anonymous Sun Jan 20 18:03:16 2019 No.10313400 >>10313389 Just the usual problem of electrons having no measured internal structure.

>>	Anonymous Sun Jan 20 18:08:23 2019 No.10313415 >>10313334 wit

>>	Anonymous Sun Jan 20 18:10:15 2019 No.10313417 >>10313363 >applying classical physics to a fucking electron

Anonymous Sun Jan 20 18:14:20 2019 No.10313429

>>10313400
Right, which is why there's no number. But it's pretty much as easy an application of occam's razor as it gets. There's not really any other plausible explanations other than that the electron is rotating in some regard.

If you assume the charge is uniformly distributed within the electron and the electron is a sphere, you probably could get a number in Hertz, because the diameter of the electron is approximately known.

If rams-saints goes to overtime I'll do it myself real quick. Also in the equation I gave the term "center of charge" is wrong, "charge analog of inertia divided by charge" would be more accurate. In this case (2/5)r^2

>>	Anonymous Sun Jan 20 18:14:21 2019 No.10313430 >>10311550 https://en.wikipedia.org/wiki/Wigner%27s_classification

>>	Anonymous Sun Jan 20 18:16:17 2019 No.10313435 >>10313417 >Physics=magic because I can't see it Copenhagen interpretation can rot in hell.

Anonymous Sun Jan 20 18:29:58 2019 No.10313469

>>10313429
>There's not really any other plausible explanations other than that the electron is rotating in some regard.
Or, you know, it could be intrinsic angular momentum, and the notion that angular momentum has to come from spinning is a bias.

If it's an actual spinning object, where does half integer angular momentum come from? It's well known in quantum mechanics that orbital angular momentum comes only in integer multiples. And where are the other possible orbital angular momentum states?

>>	Anonymous Sun Jan 20 18:30:40 2019 No.10313472 >>10313429 >>10313324 I got 2.9*10^24 Hz.

Anonymous Sun Jan 20 18:43:05 2019 No.10313496

>>10313469
>Or, you know, it could be intrinsic angular momentum, and the notion that angular momentum has to come from spinning is a bias.
I'm hoping this at least makes sense to you? Because it doesn't make sense to me. Angular momentum is a physical concept based on the mathematical concept of rotation, there's no "bias" involved. No rotation, don't call it angular momentum. Now, maybe there can exist some intrinsic magnetic field. But then that just raises more questions.

>If it's an actual spinning object, where does half integer angular momentum come from? It's well known in quantum mechanics that orbital angular momentum comes only in integer multiples. And where are the other possible orbital angular momentum states?

Where do all normal modes come from? Boundary conditions. Likely, different boundary conditions are caused by other properties of the particle. My guess is, it's caused by assymetries within the particle, but I'm not ready to divulge all my thoughts quite yet.

Anonymous Sun Jan 20 18:48:04 2019 No.10313509

>>10313496
>Angular momentum is a physical concept based on the mathematical concept of rotation
Angular momentum is a Noether current that you get by rotating your whole system. To state that elementary objects can't transform under rotations without being made of something that is spinning around an axis is a bias.

Anonymous Sun Jan 20 18:49:38 2019 No.10313512

>>10313496
>Angular momentum is a physical concept based on the mathematical concept of rotation
thats the elementary idea of it
its just like thinking of momentum as mass x velocity isnt always true
since photons have momentum and no mass, its a start, but its not always right

which is why physics is fucking gay and math is better

>>	Anonymous Sun Jan 20 19:24:54 2019 No.10313620 >>10311550 >what are books

Anonymous Sun Jan 20 20:07:24 2019 No.10313752

>>10313429
But given that we can put a very low upper limit on the radius of the electron, if you assume that the electron is spinning then a point on the electron would have to be moving faster than the speed of light in order to produce that magnetic field.

>>	Anonymous Sun Jan 20 20:14:14 2019 No.10313764 >>10313429 Fucking referees screwed the Saints. Dammit.

>>	Anonymous Sun Jan 20 20:44:38 2019 No.10313841 >>10311565 only right answer

>>	Anonymous Sun Jan 20 20:49:57 2019 No.10313848 >>10313334 No, 1/2.

>>	Anonymous Sun Jan 20 20:51:12 2019 No.10313849 >>10313752 >would have to be moving faster than the speed of light The speed of light is more changeable on the quantum scale m90.

>>	Anonymous Sun Jan 20 20:53:35 2019 No.10313853 >>10313849 Haha good one.

>>	Anonymous Sun Jan 20 20:54:30 2019 No.10313855 File: 1.59 MB, 1196x1126, kevin.png [View same] [iqdb] [saucenao] [google] >>10313849

>>	Anonymous Sun Jan 20 20:54:37 2019 No.10313856 >>10313848 Interesting unitless rotation speed.

Anonymous Sun Jan 20 20:54:48 2019 No.10313857

>>10313509
>To state that elementary objects can't transform under rotations without being made of something that is spinning around an axis is a bias.
no, that's common sense. In fact I'm sure you could easily prove it mathematically.

>>10313512
>its just like thinking of momentum as mass x velocity isnt always true
No, its like thinking of momentum as requiring a translation in space isn't always true. But the thing is, it is. Mass and energy are physical concepts. Translation, just like rotation, is a mathematical one.

>which is why physics is fucking gay and math is better
To me it's why math is gay and physics is better, but to each his own.

>>	Anonymous Sun Jan 20 20:57:02 2019 No.10313863 >>10313857 >no, that's common sense. In fact I'm sure you could easily prove it mathematically. Good luck proving that, since it's not true. Fields that transform nontrivially under rotations are well known to anyone who's ever done QFT.

Anonymous Sun Jan 20 21:01:06 2019 No.10313867

Angular momentum is a concept of classical mechanics. It arises from the fact that an object is made up of atoms, and the angular momentum is movement of the atoms around the center of mass of that object.
There's nothing to move in an electron. It's not made up of smaller parts that could move around something.

The next part might be the retard inside me speaking, but I do believe electrons and all particles that aren't made up of smaller particles are literally aggregations of energy in a dimensionless point, and only affecting other particles around it by being a lot of concentrated energy, and not by being a physical thing that has a size. Else, how could it behave like a wave?

>>	Anonymous Sun Jan 20 21:02:05 2019 No.10313869 >>10313334 No it's just 1/2.

>>	Anonymous Sun Jan 20 21:03:41 2019 No.10313871 >>10313341 This. With electrons, the actual literal definition of spin doesn't matter all that much.

>>	Anonymous Sun Jan 20 21:05:36 2019 No.10313874 >>10313363 What the fuck do you think an electron is?

Anonymous Sun Jan 20 21:08:15 2019 No.10313879

>>10313752
The circumference of an electron, or at least it's collection of charge is on the order of 10^-15 to 10^-18 m. I calculated the rotation of the electron at >>10313472 2.9*10^24 Hz. That means a point on the edge of the electron would move on the order of 10^6 to 10^9 m/s, so you can't really definitively say it's going ftl.

>>	Anonymous Sun Jan 20 21:08:25 2019 No.10313880 >>10313849 I want you guys to sit down and just imagine what our universe would be like if this was even close to true.

>>	Anonymous Sun Jan 20 21:08:28 2019 No.10313881 >>10313853 It's true, it averages out over larger scales tho.

>>	Anonymous Sun Jan 20 21:09:30 2019 No.10313883 >>10313880 Why don't you think it's true?

>>	Anonymous Sun Jan 20 21:13:15 2019 No.10313888 >>10313879 Which of end of the range of numbers did you use to calculate the angular frequency? Make sure you use the same one to get the radial speed.

>>	Anonymous Sun Jan 20 21:15:39 2019 No.10313890 >>10313881 No such phenomenon is present in QFT.

>>	Anonymous Sun Jan 20 21:24:47 2019 No.10313898 >>10313890 Is the energy state of a vacuum constant at very small scales?

>>	Anonymous Sun Jan 20 21:26:52 2019 No.10313903 >>10313898 Yes, as much as people like to pretend it's not. By definition, the vacuum state is an energy eigenstate.

>>	Anonymous Sun Jan 20 21:30:10 2019 No.10313911 >>10313752 >>10313849 >>10313879 http://bearsoft.co.uk/new_site/phys/qm-spin.pdf

>>	Anonymous Sun Jan 20 21:30:46 2019 No.10313913 >>10313903 Ignoring that you've managed to turn actual terminology into jargon (and also missing the point), then from where the Dirac sea my man?

Anonymous Sun Jan 20 21:36:10 2019 No.10313921

>>10313863
I didn't want to call you out on your B.S. but
angular momentum is the noether charge, not the noether current. The noether current is rotation. Like what are you even saying man? I can't understand your argument behind your wikipedia paraphrasing.

>>10313874
What do you think it is?

>>10313888
I used 10^-15 but I also assumed the charge was uniformly distributed. I also assumed the electron was spinning at the same speed at it's perimeter as it's center. Either could cause my number to be off by way more than 1 order of magnitude. it would be cause for concern if it was 10^20 or something, but 10^9 is easily within error.

>>	Anonymous Sun Jan 20 21:36:40 2019 No.10313922 >>10313913 You asked if the energy of the vavuum is constant at very small scales, and I said yes. Are you going to contest my answer, or just accuse me of missing the point? What does Dirac sea have to do with anything?

Anonymous Sun Jan 20 21:41:55 2019 No.10313928

>>10313921
>I didn't want to call you out on your B.S. but
>angular momentum is the noether charge, not the noether current.
You're right, I said current but meant charge. It was careless of me, but doesn't change my point.

>The noether current is rotation
No, rotation is the not the current. Rotation is the generator of the current.

>Like what are you even saying man?
Dirac fermions. Gauge bosons. They transform nontrivially under rotations.

Anonymous Sun Jan 20 22:00:00 2019 No.10313955

>>10313911
Again, makes a lot of assumptions you can't really make. The radius of an electron is an extremely hand wavy concept in the first place.

>>10313928
>No, rotation is the not the current. Rotation is the generator of the current.
Wrong again. The charge, in this case angular momentum, is the generator of the current, in this case rotation.

>Dirac fermions. Gauge bosons. They transform nontrivially under rotations.
Yes, if the axis of rotation is different than that of the spin... What I'm saying is, I don't understand what a system that transforms under rotations is supposed to prove?

>>	Anonymous Sun Jan 20 22:03:39 2019 No.10313964 >>10313955 >I don't understand what a system that transforms under rotations is supposed to prove? That angular momentum doesn't have to come from things that are spinning.

>>	high-pitched voice Sun Jan 20 22:07:09 2019 No.10313966 >>10313964 Woah wtf

Anonymous Sun Jan 20 22:12:33 2019 No.10313976

>>10313955
>Again, makes a lot of assumptions you can't really make. The radius of an electron is an extremely hand wavy concept in the first place.

I kind of agree- you can put an upper limit at least on the radius of an electron though. But the whole argument is meant to prove that electron spin is NOT like conventional spin. It's proof by contradiction of the view that the electron's spin comes from it actually "spinning" in a classical sense.

Anonymous Sun Jan 20 22:15:57 2019 No.10313980

>>10313964
it doesn't prove that. Literally every system that is not rotationally symmetric will transform under rotation. I can't begin to understand how that would begin to contribute to evidence for your point.

>>10313976
I understand, I'm saying the argument is not sufficient though.

Anonymous Sun Jan 20 22:20:10 2019 No.10313985

>>10313980
>it doesn't prove that. Literally every system that is not rotationally symmetric will transform under rotation. I can't begin to understand how that would begin to contribute to evidence for your point.

Are you denying that a Dirac field carries intrinsic angular momentum?

>>	Anonymous Sun Jan 20 22:50:50 2019 No.10314035 >>10313985 Yes. Angular momentum is due to spinors, a construct physicists defined literally to have angular momentum. It's a circular argument.

Anonymous Sun Jan 20 22:54:18 2019 No.10314043

>>10314035
>spinors
>a construct physicists defined literally to have angular momentum
Cartan defined spinors before it ever came up in physics. Because there are nontrivial representations of SO(3) (and the Lorentz group), fields can have intrinsic angular momentum.

Anonymous Mon Jan 21 00:00:40 2019 No.10314193

>>10314043
Sorry but you're misinterpreting it. Spin is a generator of rotation just like orbital angular momentum is. The difference is that rotation affects spinors differently than it does a normal position vector(notably, anti-symmetric under exchange), however the fact is that the spinor must be subject to rotation to be non-0, just like a normal vector would. It may sound like I am somewhat digressing, and I have gained better understanding which is always the goal. But I am also going to insist that the spinor is simply a convenient representation for something that is difficult to describe classically, something like >>10313201 and therefore the rotation I'm talking about is fundamentally a classical rotation.

Anonymous Mon Jan 21 00:58:15 2019 No.10314378

>>10314193
>But I am also going to insist that the spinor is simply a convenient representation for something that is difficult to describe classically, something like >>10313201 and therefore the rotation I'm talking about is fundamentally a classical rotation.
I don't understand why you would insist on that.

>>	Anonymous Mon Jan 21 01:40:09 2019 No.10314466 >>10311570 Except normal spin doesn't have the freak feature of always being exactly aligned with the measuring device.

>>	Anonymous Mon Jan 21 02:27:38 2019 No.10314536 >>10311550 You're Welcome https://www.youtube.com/watch?v=3k5IWlVdMbo&t=604s

Anonymous Mon Jan 21 06:17:42 2019 No.10314797

>>10314466
I thought that was normal if you consider how the measuring device works, since to measure spin you have to place the particles in a magnetic field which will align or anti-align them
the freaky part is that the particles always have the same spin value, positive or negative
am I wrong?

>>	Anonymous Mon Jan 21 06:32:26 2019 No.10314808 >>10313201 You are going to leap from your seat, when you realize that space-time itself is actually spinning.

>>	Anonymous Mon Jan 21 06:43:13 2019 No.10314824 xyyxx yxxyy ivvivv xyvivx

>>	Anonymous Mon Jan 21 07:22:44 2019 No.10314894 File: 3.48 MB, 256x256, Anti-Twister.gif [View same] [iqdb] [saucenao] [google] >>10314808 Precisely why I posted it, it blew my mind when I first saw it. This is the one that really set in that it is a spacial distortion.

Anonymous Mon Jan 21 13:14:47 2019 No.10315532

>>10314378
No proof, it's an interpretation. I admitted in my first post in this thread that there was no proof either way. As for why I am insisting, I hope you can agree it's a lot simpler explanation than some magical "quantum number." As above, so below, it's monkeys all the way down, etc.

That's what I hate about modern physics, there's this conception that just because the math is different the physics must be as well. The fact is there are some basic first principles in physics(mainly, causation and localization, although I understand a quantum number doesn't violate either of these) that people throw out the window just to glorify the math. To me, if you want to suggest quantum numbers are real physical objects, if you want to say a particle can really be in two places at once, the burden of proof is on YOU. And there's literally not a shred of proof in existence (don't make me laugh with the bell inequality), yet physicists still have adopted this voodoo bullshit. I'm not sure if it's religiously motivated(muh free will, muh quantum is god), or they're simply too arrogant to admit their model is nothing more than analogy.

>>	Anonymous Mon Jan 21 13:27:52 2019 No.10315568 >>10311550 electrons breakdancing

Anonymous Mon Jan 21 13:49:39 2019 No.10315625

>>10311574
>magnetic dipole moment.
This is where I get lost when it comes to spin.
I thought the magnetic dipole of an electron was caused by an actual physical spin of the electron.
But I also know "spin" isn't truly about rotation around an axis.
So does the spin of electrons to create the dipole moment have anything to do with its 1/2 spin?
Or is this one of those things that makes sense in the math, but breaks down when you try to reconcile it into plain english?

Anonymous Mon Jan 21 13:54:35 2019 No.10315642

>>10315532
>I hope you can agree it's a lot simpler explanation than some magical "quantum number."
Not the other guy, but you're right. The explanation is a lot simpler, but It's also wrong.
I'm not gonna reply to the rest because it's just too retarded.

Anonymous Mon Jan 21 14:21:58 2019 No.10315732

>>10315642
Care to give the correct explanation then?

I think most physicists would agree with my rant to at least some extent. They just don't like talking about it because it's not empirical, which I understand, but at this point, it's a discussion that needs to happen if we're going to progress in physics.

>>10315625
>I thought the magnetic dipole of an electron was caused by an actual physical spin of the electron
No it's from the 1/2 spin.

>So does the spin of electrons to create the dipole moment have anything to do with its 1/2 spin?
Again, they're the same.

It is indeed spinning as a rotation about an axis, but not like a merry go round, more like this>>10314894 which is why it has to be represented by spinons and not regular vectors.

It's hopeless to think of the electron as a point particle, it's a collection of charge, and those tendrils would represent how the charge is distributed (albeit as a continuous field and not condensed in strings like that)

Anonymous Mon Jan 21 14:26:38 2019 No.10315748

>>10315532
>I hope you can agree it's a lot simpler explanation than some magical "quantum number."
>magical "quantum number."

You say things like this, and it makes me think that you weren't listening when I was talking about Cartan studying the representations of SO(3).

>(don't make me laugh with the bell inequality)
So why should I continue taking you seriously?

>>	Anonymous Mon Jan 21 14:36:08 2019 No.10315778 Kepler's fractal

>>	Anonymous Mon Jan 21 14:42:59 2019 No.10315802 >>10313329 based answer

Anonymous Mon Jan 21 16:33:54 2019 No.10316150

>>10315748
Please read what I wrote more carefully. I fear you are a bit lost in the sauce when it comes to the math.

I take back what I said about spinors being a construct made by physicists. However, it's still just a mathematical analog. What the spinor really represents is a different type of rotation besides just plain old orbital. An example of such a rotation is this: >>10314894

If you take a rotating spherical magnet, you could model it's angular momentum in with a 3 dimensional unit vector in the direction of it's axis of rotation, just like you can with an electron. Is the angular momentum some magic variable? No, it represents how fast the bowling ball is spinning. The mathematical difference with an electron is it has half-integer values of the Casimir(or J^2) operator. All this means physically is that it takes two rotations to return to it's original state as opposed to one. There's nothing abstract, that shit is still spinning bro.

>So why should I continue taking you seriously?
Because all the bell inequality shows is that either causality was being violated OR there must exist hidden, non-local(within the scope of known variables, but ultimately local themselves) variables. Because causality being violated was such a preposterous proposition, Bell himself ORIGINALLY meant the bell inequality to prove the existence of these hidden variables. However, because this couldn't be proven, physicists decided to go with the copenhagen interpretation, which since then has been more and more misunderstood as actual physical reality. When in fact it was basically meant to just mean shut up and calculate.

>>	Anonymous Mon Jan 21 17:06:44 2019 No.10316249 >>10311550 https://www.youtube.com/watch?v=W-_4zOYTIVU

Anonymous Mon Jan 21 18:08:35 2019 No.10316452

>>10316150
You say that spinors are "just a math analog". But you have no basis for this other than that you don't like it. If you want to say there's an object actually spinning, you have to answer for why electrons can't spin faster. You have to explain why electrons have no structure.

>There's nothing abstract, that shit is still spinning bro.
Spinors are defined by how they change under rotations. There is zero requirement for them to be spinning objects. Just like vectors don't have to be spinning objects.

>Because all the bell inequality shows is that...
I really don't know how you managed to bring the Copenhagen interpretation into this.

>>	Anonymous Mon Jan 21 18:23:19 2019 No.10316492 >>10315732 >It's hopeless to think of the electron as a point particle I try not to, in general. It was just always the magnetic dipole moment that threw a monkey wrench in the "picture" I had in my head. I liked your explanation though.

Anonymous Mon Jan 21 18:41:30 2019 No.10316536

>>10316452
>Spinors are defined by how they change under rotations. There is zero requirement for them to be spinning objects.
Correct.
>Just like vectors don't have to be spinning objects.
Correct again. There is, however a requirement for the vector to be a spinning object in order to have angular momentum. The same is true of spinors. What is hard to understand about this?

>You say that spinors are "just a math analog". But you have no basis for this other than that you don't like it.
All math that describes real things is analogous.

>If you want to say there's an object actually spinning, you have to answer for why electrons can't spin faster.
Why would I have to do that?

>You have to explain why electrons have no structure.
Who said they have no structure?

Frankly, I don't have to explain anything until you provide an alternate interpretation of electron spin. The idea that spin is a classically explainable phenomenon, a rotating(albeit oddly) concentration of charge, agrees with the math and is the simplest possible explanation. If you want to posit that there are hidden dimensions involved, or whatever your understanding of spin is, then the burden of proof is on you. Again, this is not an empirical fact and I understand it is more or less a god of the gaps argument. But if your only objection is "shut up and calculate" then I feel pretty confident about my position.

Anonymous Mon Jan 21 18:55:59 2019 No.10316579

>>10316536
>There is, however a requirement for the vector to be a spinning object in order to have angular momentum. The same is true of spinors. What is hard to understand about this?
Well, there's the fact that it's not true. Any field that transforms nontrivially under rotations has angular momentum.

>Why would I have to do that?
Because, as already mentioned, if it's a spinning object, it'll have a bunch of different angular momentum modes. See e.g. hydrogen atoms.

>Who said they have no structure?
All current experiments.

Anonymous Mon Jan 21 19:06:42 2019 No.10316604

>>10316536
>I don't have to explain anything
>The idea that spin is a classically explainable phenomenon, a rotating(albeit oddly) concentration of charge, agrees with the math and is the simplest possible explanation.
So do you have an explanation or not?
If it's simple, please just tell me. An electron is clearly different from what one normally thinks of "a rotating concentration of charge" in the classical sense (a spinning ball). You said some handwavy stuff in >>10315732 but that doesn't constitute an explanation. Feel free to provide links to other resources.

Anonymous Mon Jan 21 19:31:47 2019 No.10316680

>>10316579
>Any field that transforms nontrivially under rotations has angular momentum.
This is incorrect and I'm not sure why you keep saying it. Like I said before, every field that isn't spherically symmetric transforms under rotations. You didn't acknowledge this when I told you it before and instead are choosing to sound like a broken record. I hope you don't think every such field has angular momentum?

>Because, as already mentioned, if it's a spinning object, it'll have a bunch of different angular momentum modes.
There's no reason this requires explanation only if it's a spinning object. It's just not something we know period. Regardless, consider that all the properties of a particle are related. So if the spin changes it loses all the qualities of an electron, and instead becomes a new particle or collection of particles.

>All current experiments.
what do you mean no structure? To me no structure means they don't exist, which I'm pretty sure isn't verified by experiments.

>>10316604
>you gave an explanation
>but that doesn't constitute an explanation
Are you serious?

If there's anything you don't understand, I'm happy to answer any questions. But I'm not going to repeat myself.

Still waiting for your interpretation, by the way.

>>	Anonymous Mon Jan 21 19:39:20 2019 No.10316707 >>10316680 >If there's anything you don't understand, I'm happy to answer any questions. But I'm not going to repeat myself. I'm going to stop responding now because I'm clearly being trolled. 8/10, made me reply multiple times.

Anonymous Mon Jan 21 19:40:05 2019 No.10316709

>>10316680
>This is incorrect and I'm not sure why you keep saying it. Like I said before, every field that isn't spherically symmetric transforms under rotations. You didn't acknowledge this when I told you it before and instead are choosing to sound like a broken record. I hope you don't think every such field has angular momentum?
Are you not familiar with the Wigner classification? Or Lorentz group representation theory? Do you know what it means for a field to transform nontrivially?

>Regardless, consider that all the properties of a particle are related. So if the spin changes it loses all the qualities of an electron, and instead becomes a new particle or collection of particles.
Particles which haven't been seen. That's my point.

>what do you mean no structure?
Pointlike particles without spacial extent.

Anonymous Mon Jan 21 20:27:40 2019 No.10316880

>>10316709
>Are you not familiar with the Wigner classification? Or Lorentz group representation theory?
I'm familiar with both. Are you ready to contribute or gonna just continue shitting out buzzwords you read on wikipedia?

>Do you know what it means for a field to transform nontrivially?
Do you? If so I hope you're just trolling.

>Particles which haven't been seen
photons, neutrinos, haven't been seen....?

>Pointlike particles without spacial extent.
Source?

>>10316707
>I'm going to stop responding now because I'm clearly being trolled
I'm glad. I'm sure the list of "things you don't understand" would be quite extensive.

Anonymous Mon Jan 21 20:34:07 2019 No.10316907

>>10316880
>I'm familiar with both. Are you ready to contribute or gonna just continue shitting out buzzwords you read on wikipedia?
Then you ought to know that the representation defines the intrinsic angular momentum. The fact that you don't understand this and suggest I'm just throwing out terms from wikipedia suggests that you don't really know what you're talking about.

>Do you? If so I hope you're just trolling.
It means it's not a scalar field, i.e. it has intrinsic angular momentum.

>photons, neutrinos, haven't been seen....?
Hey, guess what, those are all spin 1/2 and spin 1. You don't see a full spectrum of angular momentum that you'd expect from a physical object spinning. We don't even see any fundamental spin 3/2 particles. Now stop being obtuse.

>Source?
What the hell do you think experimental upper bounds on electron radii are?

>I'm glad. I'm sure the list of "things you don't understand" would be quite extensive.
Glad to see your bad faith extends to other people in the thread.

Anonymous Mon Jan 21 22:59:35 2019 No.10317143

>>10316907
>Then you ought to know that the representation defines the intrinsic angular momentum
If only you knew how dubious you sound. First of all angular momentum is representation independent. That's why spin can be represented in SU(2) in the first place. So I'm not sure how it can be "defined by it's representation." Second, spin angular momentum is an observable, and just like every other observable in quantum mechanics it is represented by an operator acting on a hilbert space. Hilbert spaces can represent literally anything, so the observable associated with any operator acting on such a space is as far from "intrinsic" as it gets. I feel like maybe this is what you were trying to say, but you misinterpreted it so badly that you actually thought it supported your argument when in reality it does completely the opposite.

>The fact that you don't understand this and suggest I'm just throwing out terms from wikipedia suggests that you don't really know what you're talking about.
wow, sorry I doubted the credibility of someone who claims to know the intricacies of qft yet doesn't know what a generator is. It would be more believable if you would've made a single accurate statement in relation to the concepts you keep namedropping.

>It means it's not a scalar field, i.e. it has intrinsic angular momentum.

>how do we know it has intrinsic angular momentum
>because it rotates nontrivially
>what does that mean
>it means it has intrinsic angular momentum
?
And yeah, I regret to inform you that not all vector fields have angular momentum. Ever heard of an electric field?

>You don't see a full spectrum of angular momentum that you'd expect from a physical object spinning
Why would you expect that? I can get back to you on exactly why not in a couple years, as it pertains to this thread it's a total strawman.

>What the hell do you think experimental upper bounds on electron radii are?
...And you're aware those bounds are non-0, right?

>>	Anonymous Mon Jan 21 23:01:39 2019 No.10317146 >>10316907 >>10317143 OK, I feel retarded. How can any ol' vector field have an angular momentum? Is this the same thing as Hemholtz decomposition? Pls halp

Anonymous Mon Jan 21 23:16:59 2019 No.10317173

>>10317143
>If only you knew how dubious you sound. First of all angular momentum is representation independent. That's why spin can be represented in SU(2) in the first place. So I'm not sure how it can be "defined by it's representation." Second, spin angular momentum is an observable, and just like every other observable in quantum mechanics it is represented by an operator acting on a hilbert space. Hilbert spaces can represent literally anything, so the observable associated with any operator acting on such a space is as far from "intrinsic" as it gets. I feel like maybe this is what you were trying to say, but you misinterpreted it so badly that you actually thought it supported your argument when in reality it does completely the opposite.
So you've either never heard of spin 0 representation, spin 1/2 representation, spin 1 representation, etc., or you're intentionally being obtuse again.

>wow, sorry I doubted the credibility of someone who claims to know the intricacies of qft yet doesn't know what a generator is. It would be more believable if you would've made a single accurate statement in relation to the concepts you keep namedropping.
I said generator instead of group element. You claimed rotation is a noether current. I've admitted to saying current when I meant charge, but you've never admitted to any of your mistakes.

>?
Remember that whole thing where you get angular momentum from Noether's theorem? If a field transforms nontrivially, then by necessity it has intrinsic angular momentum.

>And yeah, I regret to inform you that not all vector fields have angular momentum. Ever heard of an electric field?
Electric fields aren't the dynamical degrees of freedom, the vector potential is. And a vector potential does have angular momentum. I kind of figured it would be obvious I was talking about dynamical fields from the context of fundamental physics.

Anonymous Mon Jan 21 23:22:44 2019 No.10317186

>>10317143
>Why would you expect that? I can get back to you on exactly why not in a couple years, as it pertains to this thread it's a total strawman.
Well, gee, it's not like I've explained multiple times how all orbital angular momentum values exist naturally.

>...And you're aware those bounds are non-0, right?
And they will eternally be non-zero, because that's the nature of probing small scales. So by raising this as a point, are you saying there is no evidence that will ever be able to convince you that an electron doesn't have a spacial extent?

>>10317146
I mean vector fields in the specific sense of the dynamical gauge fields you'd see in a QFT, e.g. electromagnetic fields.

>>	Anonymous Mon Jan 21 23:24:56 2019 No.10317192 >>10317186 >QFT Well shucks, I just started EM this semester. I guess I am retarded.

Anonymous Mon Jan 21 23:29:05 2019 No.10317205

>>10317146
You're not retarded, that shouldn't make sense to you.

If the vectors represent momentum themselves(such as in a dirac field but with spinors instead of vectors), then yeah obviously it will have angular momentum.

The concept that a field can have intrinsic angular momentum sounds like schizo posting to me, but this guy seems really convinced he read it somewhere.

Anonymous Mon Jan 21 23:34:40 2019 No.10317212

>>10317192
You'll probably see angular momentum for electromagnetic waves before the end of the semester. You'll probably also see the 4-vector potential, but sometimes it's brushed under the rug and only E and B are treated seriously. However, your remark about the Helmholtz decomposition isn't far off. For the spacial components of the 4-potential, the part you get from the Helmholtz decomposition is the part that will contain electromagnetic waves.

>>	Anonymous Mon Jan 21 23:40:43 2019 No.10317222 >>10313329 >>10313848 >>10313869 1/2 what?

>>	Anonymous Mon Jan 21 23:42:39 2019 No.10317225 >>10313913 Get a load of this retard right here.

>>	Anonymous Mon Jan 21 23:45:26 2019 No.10317229 File: 577 KB, 656x554, noire.png [View same] [iqdb] [saucenao] [google] >>10313324 >Imagine being this retarded to think that the electron is actually spinning.

Anonymous Mon Jan 21 23:48:11 2019 No.10317232

>>10315532
>don't make me laugh with the bell inequality
>yet physicists still have adopted this voodoo bullshit. I'm not sure if it's religiously motivated(muh free will, muh quantum is god), or they're simply too arrogant to admit their model is nothing more than analogy
Alright you've been exposed. Back to >>>/x/ you go, pseud.

Anonymous Mon Jan 21 23:49:15 2019 No.10317234

>>10315732
>I think most physicists would agree with my rant to at least some extent
>physicists still have adopted this voodoo bullshit. I'm not sure if it's religiously motivated(muh free will, muh quantum is god), or they're simply too arrogant to admit their model is nothing more than analogy
lol

>>	Anonymous Mon Jan 21 23:53:20 2019 No.10317239 File: 74 KB, 645x729, 1517429337730.png [View same] [iqdb] [saucenao] [google] >>10316680 >To me no structure means they don't exist

Anonymous Tue Jan 22 00:11:29 2019 No.10317264

>>10317173
>So you've either never heard of spin 0 representation, spin 1/2 representation, spin 1 representation, etc.
Those are not representations of each other. They are independent representations of different eigenstates of J^2. The representation is dependent on the angular momentum, not the other way around. I guess that could be what you meant?

>but you've never admitted to any of your mistakes.
I did admit that spinors were not invented by physicists.

>Remember that whole thing where you get angular momentum from Noether's theorem? If a field transforms nontrivially, then by necessity it has intrinsic angular momentum.
Nope. Noether's theorem only makes a claim about if a quantity is conserved, not if that quantity is present or not. I can't tell if you're really this clueless or just terrible at explaining yourself. It might help if you posted some resources, instead of repeating this baseless nonsense over and over?

>And a vector potential does have angular momentum
oh no...

>>10317186
>Well, gee, it's not like I've explained multiple times how all orbital angular momentum values exist naturally.
...
spin isn't orbital angular momentum....

>So by raising this as a point, are you saying there is no evidence that will ever be able to convince you that an electron doesn't have a spacial extent?
Not at all! But first there has to be, you know, evidence.

>>10317229
>>10317232
>>10317234
>>10317239
cringe

Anonymous Tue Jan 22 00:19:55 2019 No.10317279

>>10317264
>The representation is dependent on the angular momentum, not the other way around.
The representation is defined by how it transforms under Lorentz transformations. The angular momentum is a result from that.

>Nope. Noether's theorem only makes a claim about if a quantity is conserved, not if that quantity is present or not.
Are you trying to trying to deny that we work with Lorentz invariant field theories?

>It might help if you posted some resources, instead of repeating this baseless nonsense over and over?
Look at the angular momentum operator for a Dirac field in Peskin and Schroeder, or any other source.

>spin isn't orbital angular momentum....
If it's from something rotating around an axis like you claim, then yes, it is.

>Not at all! But first there has to be, you know, evidence.
I think the precise predictions of quantum electrodynamics, where the electron is treated as having no spacial structure, are pretty good evidence.

>>	Anonymous Tue Jan 22 00:28:57 2019 No.10317288 >>10311550 You do it to win.

Anonymous Tue Jan 22 00:37:27 2019 No.10317304

>>10317279
>The representation is defined by how it transforms under Lorentz transformations.
I disagree but I don't care to make this semantic argument.

>Are you trying to trying to deny that we work with Lorentz invariant field theories?
No. Does the fact that we do address my argument or support yours?

>Look at the angular momentum operator for a Dirac field in Peskin and Schroeder, or any other source.
oh, you mean the angular momentum operator that acts on angular momentum basis vectors?

>If it's from something rotating around an axis like you claim, then yes, it is.
Clearly you haven't even begun to understand my argument...

>I think the precise predictions of quantum electrodynamics, where the electron is treated as having no spacial structure, are pretty good evidence.
There are precise predictions that can be made treating whole planets as point masses. I don't think doing the same for a 10^-15 m object will affect the results much.

>>	Anonymous Tue Jan 22 00:56:59 2019 No.10317327 >>10311550 >Unironically what is spin? The asymmetry of the fundamental String.

Anonymous Tue Jan 22 00:57:44 2019 No.10317330

>>10317304
>No. Does the fact that we do address my argument or support yours?
Well, if you accept Noether's theorem, then you have to agree that we get angular momentum, the conserved charge, by looking at how fields transform under rotation.

>oh, you mean the angular momentum operator that acts on angular momentum basis vectors?
Uhh... the angular momentum operator given in terms of the fields, which is eq. 3.111 in my edition. It acts on arbitrary states...

>Clearly you haven't even begun to understand my argument...
I'm not the one who calculated an electron's rotational speed by treating it as a uniformly distributed spherical charge.

>There are precise predictions that can be made treating whole planets as point masses
Sure, if you ignore all the predictions that don't work for treating planets as point masses, such as actual photographs. I don't think you proved the point you think you did.

Anonymous Tue Jan 22 01:47:56 2019 No.10317397

>>10317330
>then you have to agree that we get angular momentum, the conserved charge, by looking at how fields transform under rotation.
If the action due to the legrangian of a field doesn't change under rotation, but the legrangian is dependent on the rate of rotation, then the rate of rotation(which, when multiplied by inertia, is the angular momentum) must be constant. This follows simply from the euler-legrange equations(for single variables), and also from the fact that delta action=0. And that's all there is to noether's theorem. But how does this tell us anything about the angular momentum itself?

>Uhh... the angular momentum operator given in terms of the fields,
The eigenvalue of the operators which act on the field has no inherit meaning. The dirac field is constructed to be consistent with the premise that this eigenvalue is spin.

>I'm not the one who calculated an electron's rotational speed by treating it as a uniformly distributed spherical charge.
I'll admit I was mistaken to do that.

I actually wouldn't disagree with the lack of structure an electron, it is more like a point of rotation, but my thoughts aren't really developed enough for the level of rigor you seem to be demanding.

Anonymous Tue Jan 22 01:55:35 2019 No.10317408

>>10317397
>But how does this tell us anything about the angular momentum itself?
Noether's theorem tells you HOW to calculate angular momentum from how your fields transform.

>The eigenvalue of the operators which act on the field has no inherit meaning. The dirac field is constructed to be consistent with the premise that this eigenvalue is spin.
First of all, you're the one who brought up the eigenvalues. I just said "look at the operator". That operator comes from Noether's theorem, and includes two terms. Second of all, the eigenvalue definitely does have an inherent meaning. By its construction from Noether's theorem, it's angular momentum.

>>	Anonymous Tue Jan 22 02:33:02 2019 No.10317479 Imagine our universe had no stars, and only a bucket of water. Would spinning the bucket cause the edges of the water to rise up the sides?

Anonymous Tue Jan 22 02:36:37 2019 No.10317484

>>10317408
>Noether's theorem tells you HOW to calculate angular momentum from how your fields transform.
It doesn't and I've never heard such a thing. Noether's theorem doesn't tell you nearly as much as you think it does. Care to outline what you believe this process to be, though?

>the eigenvalue definitely does have an inherent meaning. By its construction from Noether's theorem, it's angular momentum.
It's not. It tells you the quantum state's value in the projective representation of the lie group of SO(3). The eigenvalue could mean anything, as long the state is an eigenstate of the casimir invariant J^2, and it would be mathematically equivalent to a fermionic spin state or field.

>>10317479
Yes as long as their is friction between the bucket and the water.

Anonymous Tue Jan 22 02:46:41 2019 No.10317498

>>10317484
>It doesn't and I've never heard such a thing. Noether's theorem doesn't tell you nearly as much as you think it does. Care to outline what you believe this process to be, though?
... Are you serious? Given a Lagrangian and field transformations which leave the action invariant, Noether's theorem gives you an equation for calculating the conserved current density. Integrate the time component of that current density (a.k.a. the charge density) over all of space, and there's your angular momentum. This is covered in probably every field theory book and course, even classical field theory. The non-field version is covered in classical mechanics when Lagrangians and Hamiltonians are introduced. Even the wikipedia page has the equation.

Anonymous Tue Jan 22 03:55:09 2019 No.10317628

>>10317498
>Noether's theorem gives you an equation for calculating the conserved current density
Dude, this is just simply not true. The equation you get sets the time derivative of angular momentum =0. Integrate with respect to time and you get an arbitrary constant.

Are you just saying the angular momentum can be calculated from dL/dq* (if q* is q dot, and q is angle)? Well yeah, but first of all that's euler-legrange, which precedes noether's theorem. Second, even if there was a non-zero angular velocity dependence of the legrangian, with no actual rotation occuring, the legrangian is based on the QFT which you are working in, which is not intrinsic. At the end of the day it's a circular argument.

Anonymous Tue Jan 22 10:54:15 2019 No.10318154

>>10317628
>Dude, this is just simply not true.
Uhh, yes it is. Let me say it again: given a Lagrangian and the field transformations that leave the action unchanged, Noether's theorem gives you an equation. Just open any field theory book. Do you want me to post a picture from one?

>>>10317628
>the legrangian is based on the QFT which you are working in, which is not intrinsic. At the end of the day it's a circular argument.

Okay, now you"re moving goalposts. We were talking about the angular momentum of a Dirac field. You insisted the operator I referred you to in Peskin, which came from Noether's theorem, had nothing to do with angular momentum.

>>	Anonymous Tue Jan 22 16:07:09 2019 No.10318734 >>10311550 Can someone explain what the pauli matrices actually are? I know they're the basis for 2 dim matrix representations of a vector in 3 dim space. Does a more intuitive definition for them exist?

>>	Anonymous Tue Jan 22 16:09:14 2019 No.10318737 >>10317479 According to machs principle, no

Anonymous Tue Jan 22 16:24:26 2019 No.10318777

>>10318154
>given a Lagrangian and the field transformations that leave the action unchanged, Noether's theorem gives you an equation
The legrangian is the ONLY thing you need in order to obtain the motion equations. Noether's theorem is just another consequence of the principle of least action.
>Do you want me to post a picture from one?
Please do. Even though I know you're just going to post fucking euler-legrange.

>You insisted the operator I referred you to in Peskin, which came from Noether's theorem, had nothing to do with angular momentum.
And it doesn't. I was obviously referring to the matrix representation of the operator. The angular momentum it represents isn't mathematically intrinsic in any sense of the word.

>>	Anonymous Tue Jan 22 18:09:40 2019 No.10318987 File: 15 KB, 1134x117, noether.png [View same] [iqdb] [saucenao] [google] >>10318777 Peskin and Schroeder, giving an equation for the conserved current corresponding to a symmetry.

>>	Anonymous Tue Jan 22 18:12:15 2019 No.10318996 >>10313341 one smart person in this thread

>>	Anonymous Tue Jan 22 18:13:09 2019 No.10318997 >>10311550 It's literally and physically which direction the particle is spiraling through space as an unbound function. In a bound state it's the same thing but there's different consequences.

Anonymous Wed Jan 23 06:38:47 2019 No.10320175

>>10318987
I thought about it for a while and did some research, and you might be right. Now that I think about it, momentum not necessarily relying on motion is one of the basic differences of QM. I mean the momentum operator is just the gradient of the probability amplitude with respect to x. I still think in the simple case, a change in probability amplitude between x's implies some time independence, but this only applies to linear and orbital momentum, and doesn't hold for generalized momentum.

>>10318996
He's smart because he provides no information whatsoever?

Anonymous Wed Jan 23 07:06:05 2019 No.10320213

>>10311550
In string theory, it literally is the fact that the fundamental string is rotating. You can't think of a particle as rotating, of course, but if you think of particles as just an approximation to very short fundamental strings, spin is exactly what you'd think it is for the strings, and this becomes this unintuitive, intrinsic angular momentum only because we've approximated a string, which has length, by a particle, which doesn't. In this limit, the different directions a particular vibrational mode of the string can vibrate in become the different polarisations of the corresponding particle.
This is a perfect explanation for the bosonic string, but you might worry that this is a bit of a non-answer for the superstring because it has worldsheet fields that are spinors, but the worldsheet theory is conformal so there are no particle states -- there is nothing to ask "how can a particle have spin if a particle can't spin". You have to focus on just the quantum fields, and you can think of these fields as what you get from quantising a Grassmann-valued (i.e anti-commuting) classical field. It will have two components, and we might call them spin up and spin down, but really we're just saying there's a field with two components and it anti-commutes with itself.

>>	Anonymous Wed Jan 23 07:09:13 2019 No.10320217 >>10320213 >muh string theory Call me when it makes testable predictions

>>	Anonymous Wed Jan 23 08:46:40 2019 No.10320343 >>10311559 In English please?

>>	Anonymous Wed Jan 23 09:13:30 2019 No.10320384 >>10320343 https://www.tfd.com/intrinsic https://www.tfd.com/angular https://www.tfd.com/momentum

>>	Anonymous Wed Jan 23 09:17:21 2019 No.10320392 >>10320384 https://en.wikipedia.org/wiki/Nigger

>>	Anonymous Wed Jan 23 09:37:01 2019 No.10320428 File: 123 KB, 500x325, YutoSasaki_Headshot.png [View same] [iqdb] [saucenao] [google] >>10311550 I am currently in a game of Cs:go playing Dust 2 ct

>>	Anonymous Wed Jan 23 12:59:59 2019 No.10320878 >>10320217 I'm not talking about testable predictions, I'm saying it makes spin much more intuitive.

>>	Anonymous Wed Jan 23 14:25:10 2019 No.10321052 File: 102 KB, 1000x743, 1000px-Faraday-effect.svg[1].png [View same] [iqdb] [saucenao] [google] >>10311550 Magnetism

Anonymous Wed Jan 23 15:14:54 2019 No.10321173

>>10320343
Angular momentum that a particle has by its very nature. Just like the way the corresponsing field changes under an electromagnetic U(1) gauge transformation gives the particle a certain electric charge, changing under rotation (or general Lorentz transformations) means a particle has a certain angular momentum.

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/sci/ - Science & Math