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gnardog777
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I think I understand the gist of it. Is it a property that exhibits properties of angular momentum, without actually spinning, because it isn't made of anything else as far as we know, and has no inner structure?
Drakkith said:I think you hit the nail right on the head. It is simply a property of particles, similar to how electric charge is a property.
gnardog777 said:I think I understand the gist of it. Is it a property that exhibits properties of angular momentum, without actually spinning, because it isn't made of anything else as far as we know, and has no inner structure?
Drakkith said:Angular momentum is associated with rotating objects, such as a top or a rotating planet. I don't know if it will help, but you can look here: http://en.wikipedia.org/wiki/Angular_momentum
Quantum mechanics kind of makes these things difficult to understand since they don't quite work like macroscopic objects do. You never see a basketball that can only spin at certain speeds or that needs to spin around twice to get around once for example.
Drakkith said:To my knowledge there is no way to understand it conceptually. It is purely a result of observations and math. The particle isn't spinning around on it's axis, yet it still possesses angular momentum! It doesn't make any sense!
Drakkith said:Maverick I barely understood anything you said lol.
maverick_starstrider said:To the OPs inability to conceptualize spin let me say this, classical mechanics is the laws of physics that govern the macroscopic universe we interact with in our day to day lives, it governs billiard balls and tops and gyroscopes, etc. In the atomic realm classical physics gave wrong answers and thus a new physics had to be developed called quantum mechanics. If one could apply classical intuition to all of quantum mechanics then quantum mechanics WOULD BE classical mechanics, which it's not. The fact that it exists at all tells you that our world of billiard balls and tops is INSUFFICIENT in this realm.
As to Drakkith spin is one of those things that the MORE abstract your understanding and thinking the more it makes sense. Many will say you prove the existence of spin by postulating the Dirac equation on the electron by considering all terms in the action (including spinors) that obey lorentz invariance and quantizing to find an extra degree of freedom. Well this is true, it can actually come straight from QM (not QFT). I'd recommend reading the 3rd chapter of Ballentine''s book on this. In a nutshell you have the result that the angular momentum generates angular motion and you can naively find the form of it which is akin to the classical case. However, you realize that you can obtain the same relations if you allow an extra term with no dependence on q or p (intrinsic), you get the same relations. In this way spin is something like a gauge, a redundancy of description of the angular momentum. You can also prove that such an intrinsic term CAN'T be added to the linear momentum.
gnardog777 said:I understood the first paragraph, but you completely lost me on the second one. I can't wait until I go to college.
Intrinsic angular momentum, also known as spin, is a fundamental property of quantum particles that describes their intrinsic rotation. It is a form of angular momentum that cannot be explained by the particle's mass or orbital motion, and is inherent to the particle itself.
Intrinsic angular momentum is different from orbital angular momentum in that it does not involve physical rotation around an axis, but rather it is an intrinsic property of the particle itself. Orbital angular momentum, on the other hand, is associated with the motion of the particle around an axis.
Intrinsic angular momentum, or spin, is measured in units of angular momentum, which is typically expressed in units of ħ (h-bar), which is equal to 1.0545718 × 10^-34 joule seconds.
The spin quantum number, denoted as s, is a quantum number that describes the magnitude of the intrinsic angular momentum of a particle. The value of s determines the allowed values of the spin angular momentum, which can be either half-integer or integer values.
Intrinsic angular momentum, or spin, has many applications in physics, including in quantum computing, nuclear magnetic resonance imaging (MRI), and electron spin resonance spectroscopy. It also plays a crucial role in determining the properties of atoms and molecules, and has led to discoveries in quantum mechanics and particle physics.