电子自旋凭什么是1/2

[leiya]

明明就是1，角动量量子化可以理解，但是怎么能随便变？随便定义？

https://faculty.pku.edu.cn/leiyian/zh_C ... tm#article

英文版：

https://faculty.pku.edu.cn/leiyian/en/a ... tm#article

[朔方节度使]

自旋是1的话是玻色子。宇宙光有玻色子的话没办法构成物质

[leiya]

自旋是1的话是玻色子。宇宙光有玻色子的话没办法构成物质

自旋是1，这是客观值，物理值，不能改。不能因为你的理论需要它是1/2，就改成1/2

还因为说不清，就改成非物理的(不是经典角动量)

[朔方节度使]

自旋是1，这是客观值，物理值，不能改。不能因为你的理论需要它是1/2，就改成1/2

电子的自旋是可以和外界，宏观的磁场发生作用的。你改了，这个作用就大了一倍。可是实际上它就是那么多

[Amorphous]

电子的自旋是可以和外界，宏观的磁场发生作用的。你改了，这个作用就大了一倍。可是实际上它就是那么多

hbar 减半即可

[winniepooh2018]

自旋是1，这是客观值，物理值，不能改。不能因为你的理论需要它是1/2，就改成1/2

还因为说不清，就改成非物理的(不是经典角动量)

You need to ask ChatGPT

(a) Quantum states and symmetry

In quantum mechanics, every particle’s wavefunction must transform in a definite way when the reference frame is rotated.
These transformation rules fall into representations of the rotation group SO(3) or, more precisely, its double cover SU(2).

(b) Two kinds of representations
• Integer spins (0, 1, 2, …) correspond to bosons — fields that return to the same state after a 360° rotation.
• Half-integer spins (½, 3/2, …) correspond to fermions — fields that only return to the same physical state after a 720° rotation (a 360° rotation multiplies the wavefunction by –1).

The Dirac equation, which is the relativistic quantum equation for the electron, demands that the electron’s wavefunction transform according to a spinor representation of the Lorentz group.
That spinor representation has spin ½, not 1.

[leiya]

You need to ask ChatGPT

(a) Quantum states and symmetry

In quantum mechanics, every particle’s wavefunction must transform in a definite way when the reference frame is rotated.
These transformation rules fall into representations of the rotation group SO(3) or, more precisely, its double cover SU(2).

(b) Two kinds of representations
• Integer spins (0, 1, 2, …) correspond to bosons — fields that return to the same state after a 360° rotation.
• Half-integer spins (½, 3/2, …) correspond to fermions — fields that only return to the same physical state after a 720° rotation (a 360° rotation multiplies the wavefunction by –1).

The Dirac equation, which is the relativistic quantum equation for the electron, demands that the electron’s wavefunction transform according to a spinor representation of the Lorentz group.
That spinor representation has spin ½, not 1.

你把我贴的文章给ChatGPT （链接就行），再问它

[Amorphous]

自旋如果不是1/2，电荷也得改变？

[winniepooh2018]

有了AI理论家都得下岗：
If you’re interested, we can ask:
• Does the article derive all standard spin-½ phenomena (Pauli exclusion, Dirac equation, spinor behaviour) from its reinterpretation?
• Does it make predictions different from standard theory, and have those been tested?
• Are there peer-reviewed papers supporting this reinterpretation, or is it primarily a blog/personal article?
• How does it treat other spin-½ particles (muon, neutron, etc) and whether they also “really” have spin = 1 in their rest frame?

[winniepooh2018]

你把我贴的文章给ChatGPT （链接就行），再问它

北大的也翻墙问学术了、比中山大学翻墙做五毛强

Here are some points where the article diverges from or simplifies what mainstream quantum mechanics and relativity say:
1. Electron spin = ½ is a representation theory result
• In relativistic quantum mechanics, the electron is described by the Dirac equation, which leads to a 4-component spinor field. The allowed values of spin (intrinsic angular momentum) emerge from the fact that the wavefunction transforms under the “spin-½” representation of the rotation (and Lorentz) group.
• That intrinsically gives s = 1/2 and thus two possible S_z = \pm \frac12 \hbar.
• The article’s re-interpretation (that in the electron’s own rest frame it’s \hbar) would require re-interpreting that representation theory result or altering how we treat frames and transformations.
2. Thomas precession is real, but not enough to change spin quantum number
• Thomas precession is a relativistic correction which arises when you combine orbital motion + special relativity + non-inertial frames. It explains factors of ½ in, e.g., spin–orbit coupling in atomic physics.
• But standard theory holds that the fundamental spin s = 1/2 remains the same in all inertial frames — you don’t change the quantum number just by changing frames.
• The article implies the ½ is literally due to frame transformation. That’s a non-standard claim — I did not find mainstream literature saying “electron intrinsic spin is actually 1” and only appears ½ because of observer frame.
3. Magnetic moment & g-factor
• It’s true that the electron’s magnetic moment is \mu = g \frac{e\hbar}{2m} with g \approx 2. That is often loosely compared to what you’d expect for a rotating charged sphere with angular momentum \hbar.
• But that doesn’t imply the electron’s intrinsic angular momentum is \hbar; instead the “extra” factor of 2 comes from relativistic quantum effects (including Dirac theory).
• The article says “the magnetic moment aligns exactly with classical expectation if you assume angular momentum = \hbar”. It then uses that to argue the intrinsic spin is ℏ. But the standard interpretation is: electron spin = ½ so S = \sqrt{1/2(1/2+1)}\,\hbar = \frac{\sqrt3}{2}\hbar; the magnetic moment then emerges accordingly, with g ≈ 2 as predicted by Dirac theory. The “classical expectation” is not taken as a primary defining fact.
4. 720° rotation property of spinors
• A well-known result: spin-½ particles exhibit a minus sign after a full 360° rotation (you need 720° to return to the same quantum state). That comes from the spinor representation of SU(2).
• The article dismisses this as “mathematical artefact” and says it’s not physical. Standard quantum mechanics treats this as a real feature of how spinors behave under rotations; whether one calls it “physical” vs “mathematical” might be semantics, but in the ordinary interpretation it is a consequence of the spin-½ state. The article challenges that.
5. Frame of reference vs intrinsic property
• The article emphasizes that the “½” arises because one is measuring in the nuclear rest frame, while the “true” electron rest frame would give full ℏ. That implies the spin quantum number is not intrinsic but relative.
• Standard QM holds that spin is intrinsic and frame-invariant (apart from direction). Changing observer frames changes measured components (e.g., boosting changes spin projection), but not the spin quantum number itself.

[leiya]

北大的也翻墙问学术了、比中山大学翻墙做五毛强

Here are some points where the article diverges from or simplifies what mainstream quantum mechanics and relativity say:
1. Electron spin = ½ is a representation theory result
• In relativistic quantum mechanics, the electron is described by the Dirac equation, which leads to a 4-component spinor field. The allowed values of spin (intrinsic angular momentum) emerge from the fact that the wavefunction transforms under the “spin-½” representation of the rotation (and Lorentz) group.
• That intrinsically gives s = 1/2 and thus two possible S_z = \pm \frac12 \hbar.
• The article’s re-interpretation (that in the electron’s own rest frame it’s \hbar) would require re-interpreting that representation theory result or altering how we treat frames and transformations.
2. Thomas precession is real, but not enough to change spin quantum number
• Thomas precession is a relativistic correction which arises when you combine orbital motion + special relativity + non-inertial frames. It explains factors of ½ in, e.g., spin–orbit coupling in atomic physics.
• But standard theory holds that the fundamental spin s = 1/2 remains the same in all inertial frames — you don’t change the quantum number just by changing frames.
• The article implies the ½ is literally due to frame transformation. That’s a non-standard claim — I did not find mainstream literature saying “electron intrinsic spin is actually 1” and only appears ½ because of observer frame.
3. Magnetic moment & g-factor
• It’s true that the electron’s magnetic moment is \mu = g \frac{e\hbar}{2m} with g \approx 2. That is often loosely compared to what you’d expect for a rotating charged sphere with angular momentum \hbar.
• But that doesn’t imply the electron’s intrinsic angular momentum is \hbar; instead the “extra” factor of 2 comes from relativistic quantum effects (including Dirac theory).
• The article says “the magnetic moment aligns exactly with classical expectation if you assume angular momentum = \hbar”. It then uses that to argue the intrinsic spin is ℏ. But the standard interpretation is: electron spin = ½ so S = \sqrt{1/2(1/2+1)}\,\hbar = \frac{\sqrt3}{2}\hbar; the magnetic moment then emerges accordingly, with g ≈ 2 as predicted by Dirac theory. The “classical expectation” is not taken as a primary defining fact.
4. 720° rotation property of spinors
• A well-known result: spin-½ particles exhibit a minus sign after a full 360° rotation (you need 720° to return to the same quantum state). That comes from the spinor representation of SU(2).
• The article dismisses this as “mathematical artefact” and says it’s not physical. Standard quantum mechanics treats this as a real feature of how spinors behave under rotations; whether one calls it “physical” vs “mathematical” might be semantics, but in the ordinary interpretation it is a consequence of the spin-½ state. The article challenges that.
5. Frame of reference vs intrinsic property
• The article emphasizes that the “½” arises because one is measuring in the nuclear rest frame, while the “true” electron rest frame would give full ℏ. That implies the spin quantum number is not intrinsic but relative.
• Standard QM holds that spin is intrinsic and frame-invariant (apart from direction). Changing observer frames changes measured components (e.g., boosting changes spin projection), but not the spin quantum number itself.

原来单篇文章不行，还需要上下文。我前面还有一篇关于费米子的文章，后面有一篇关于粒子自旋灾难的文章，但是基础是全局诠释的框架

[leiya]

关于费米子：

站内帖子：费米子：从神秘到电磁物理

[leiya]

电子自旋1/2的逻辑链条：电子的经典自旋是1，对应的磁矩跟实验一致，与经典理论一致。
量子力学只是经典力学的频谱形式，不应该改变电子的自旋。
但电子自旋在原子中对角动量的贡献的确是1/2，这可以从谱线上看出来，也和量子力学的频谱分析图像一致。
但这是因为托马斯进动，经典条件下也会表现为1/2。
电子的本体自旋角动量还是1，在原子中角动量为1/2本身就是证明(因为存在托马斯进动)，也和磁矩测量数据一致，不需要g因子
g因子是一个经典物理中不存在的概念，或者说恒为1

[Rabboni]

旋个几把毛，量子这几把玩意看不见摸不着，说不定显微镜看到的都是几把假象。

[leiya]

旋个几把毛，量子这几把玩意看不见摸不着，说不定显微镜看到的都是几把假象。

这就叫虚无论，玻尔喜欢

[Waa]

尼玛，一个轨道里面只能容纳两个电子。

要是能容纳四个电子，怕是要1/4了。

角动量是 牛顿力学产生的概念，后来发现不太对，也懒得改了。

现在叫自旋量子数，你个老古董！

[winniepooh2018]

旋个几把毛，量子这几把玩意看不见摸不着，说不定显微镜看到的都是几把假象。

你看量子和看包子一样肤浅