# spin

1. ### I Ontology of spin measurement

Summary: If a measurement outcome depends on the measurement setup, is de measured not real or the measurement? If the factual outcome of an electron-spin measurement depends on the orientation of the SG magnet, for instance up or down in one orientation and left or right in the other, does...

9. ### Spin Annhilation and Creator Operators Matrix Representation

1. Homework Statement Given the expression s_{\pm}|s,m> = \hbar \sqrt{s(s+1)-m(m\pm 1)}|s,m \pm 1> obtain the matrix representations of s+/- for spin 1/2 in the usual basis of eigenstates of sz 2. Homework Equations s_{\pm}|s,m> = \hbar \sqrt{s(s+1)-m(m\pm 1)}|s,m \pm 1> S_{+} = \hbar...
10. ### B Doesn't the choice of measurement prove free will

I was reading the free will theorem and it basically says that subatomic particles and observers have to have free will because there's nothing prior to measurement that predetermines the outcome. Here's more: The free will theorem states: Given the axioms, if the two experimenters in question...
11. ### A Weinberg book-spin statistics

in this equation $J_{ \overline{ \sigma } \sigma }^{(j)}$ what are they sigma bared ? Thanks <mentor edit Latex>
12. ### Spin of a nucleus within an external magnetic field.

When a nucleus is placed inside an external magnetic field, it aligns itself parallel to the field, as that is the most stable position for it to be in. In more technical terms: it acquires an alpha spin. When you shine radio waves at this nucleus, it absorbs energy and flips over anti-parallel...
13. ### Torque on a DC motor spinning a wheel horizontally

I need a 12v DC with appropriate torque. In my design, the axle of the motor would be pointed straight in the air and I want to affix a wheel to it and have the wheel spin flat, sort of like a pottery wheel sort of design. I know what the wheel is made of, its dimensions and approximate weight...
14. ### I Angular momentum and spin unit

I know that spin is a type of intrinsic angular momentum. For electron spin is (1/2)ħ . But unit of (1/2)ħ is J.s, which is not the unit of angular momentum. Can you please explain this discrepancy?

30. ### Composite Spin 1/2 System Probability Question

1. Homework Statement Two spin $\frac 12$ particles form a composite system. Spin A is in the eigenstate $s_z = + \frac 12$ and Spin B is in the eigenstate $s_x = + \frac 12$ What is the probability that a measurement of the total spin will give the value $0$? 2. Homework Equations I...