OHANIAN WHAT IS SPIN PDF DOWNLOAD!
Of the three view points described by you, following article supports the third view point describing precessional motion. In this article Spin operator is introduced. Abstract. According to the prevailing belief, the spin of the electron or of some other particle is a mysterious internal angular momentum for which no concrete physical picture is available, and for which there is no classical analog. associated with theDirac Lagrangian density, Ohanian showed that spin angular momentum arises from a circular flow of energy in the electron.
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[physics/] What is spin?
My efforts on quantum mechanics has been to look at things at a qubit level, where one reduces the number of degrees of freedom down to an absolute minimum. So the quantum theories that arise this way look inconsistent from the outset. With QCD there are composite states that arise, and the issue of their Lorentz transformation properties is extremely non-trivial, a problem that ohanian what is spin be well-understood by anyone who knows the theory of finite nuclei at all well.
The perturbation theory is mapped on to real hadronic data only by means of great difficulty, by introducing structure functions and fragmentation functions, which are after all, probabilities and not probability amplitudes.
They're doing everything in the quantum way because the world is quantum, stupid. But that's something else than saying that particles aren't moving, decaying, spinning, or doing other things.
Physics > Classical Physics
When we say just "moving" or "spinning", we should never assume that it means "moving in the classical sense" or "spinning in the classical sense" — which is the huge mistake that Aidan is explicitly and proudly doing — because this huge mistake means that we fool ourselves into thinking that the "classical sense" is the "normal sense" or "default sense" or the "sense we should always assume".
Now, Aidan says ohanian what is spin the electron is not spinning because it's pointlike. Even if we adopt the usual definitions that were developed in the classical framework, this statement by Aidan is wrong at both levels. First, it's not true that the electron is strictly point-like.
Before the Planck scale, all particles have to have an internal ohanian what is spin because quantum gravity doesn't allow distances shorter than the Planck length to be resolved. The internal architecture of particles therefore can't be "strictly and sharply point-like".
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In all perturbative string vacua, the electrons are vibrating strings occupying space comparable to the string length, a few orders of magnitude longer than the Planck length and indeed, the spin may be understood as coming from some internal degrees ohanian what is spin freedom that are localized at an extended object.
In fact, the stringy picture of the spin tells us exactly where the reasoning that pointlike or tiny objects can't carry a nonzero or rather large angular momentum breaks down.
The string is locally a very heavy object — the tension or the linear mass density of the fundamental string in string theory is huge — and the ohanian what is spin of this string just a string length away from the center of mass has a big, Planck's-constant-sized impact on the angular momentum.
My broader point is that Aidan's attempt to treat the proton's spin as something qualitatively different from the electron's spin is totally misguided as well.
It's absolutely the same property or process, when it comes to the right mathematical ohanian what is spin as well as its measurable consequences. The spin carried by the proton is totally the same thing and has the same magnitude as the spin carried by the electron!
The only difference is that we already realize that the proton is a composite, extended particle which is why the angular momentum may be visualized as the motion of the components around the axis, at a nonzero distance from it. The electron is not composite in the Standard Model and most likely, it will always be elementary in any quantum field theory correctly and usefully approximating the phenomena around us.
But at the end, it's also an extended object — a string or whatever quantum gravity tells you quantum gravity doesn't allow you to make ohanian what is spin that are strictly point-like — so it's qualitatively analogous to the proton.
And the naive argument that an angular momentum that would be this large would require a very light particle such as the electron to rotate superluminally simply has loopholes because the lightness of the particle may arise ohanian what is spin and in string theory and perhaps many other descriptions explicitly does arise — from cancellations of large contributions to the mass.
The second level of Aidan's proposition is conceptually misguided, too. He says that a particle isn't allowed to be pointlike for it to be spinning.
But that's also false. Check your definition of the rotation or the spin in your closest encyclopedia. The "spin" is the rotation around an axis that goes through the center of mass while the rotation around an external axis is "orbital motion" composed of ohanian what is spin.