What is Spin: Definition and 1000 Discussions

OK I'm super frustrated.. I spent 50min typing the whole text here earlier and click preview only to be told I was logged out. Click back and and all was gone. Damn.. Ok here's the question, AGAIN. Weight: 1kg Type: Flywheel, OD is 80mm, ID is 40mm if that matters. So that's a typical...

In the article, "What is spin", by Hans C. Ohanian we are shown how to take the wave-function for a Dirac electron with spin up and localized in space and then determine the momentum density in the Dirac field. The momentum density divides into two parts, a part that depends on the motion of the...

Hello, I usually just lurk around the forums as a first year engineering student, but I'm 27 years old. I have my bachelor's in Accounting, but I'm not very passionate about it...anyway, that's a whole different thread, but the point I'm getting across here is that my practical knowledge of...

I tried searching through but didn't find this asked. If the spin of the particle detected at LHC comes back as 2, for instance, does it mean it's not a higgs boson? There are 5 higgs in supersymmetry, do they all have spin 0?

Hi, Just a quick question: When people talk about an atom's spin do they actually mean it is physically spinning or is it a word for some different process or property of the atom - if so, what property is this? Thank you for your time.

What is the spin direction of the electrons through the ferromagnetic material? It will become parallel or antiparallel? I was confused because the scattering rate and conductivity both depend on the density of state at Fermi level. For ferromagnetic material, is it right to say that at the...

In General Relativity, the assumption is made that the stress-energy tensor Tαβ is symmetric. However, if there are particles with intrinsic spin, then this assumption is false, as described here: http://en.wikipedia.org/wiki/Spin_tensor The spin tensor Sαβμ satisfies: ∂μ Sαβμ = Tβα -...

Hi, I am scratching the surface of information regarding particle physics. I have a basic understanding of standard model. What I am not quite understanding is what 'spin' is. I know that all fermions have a spin of 1/2, but what exactly is spin? Thanks

Hi, All articles on spin liquids I've seen treat them as insulators. This is understandable in the context in which they were first introduced i.e. the resonating valence bond state in which every electron is singlet-ed with every other, and thus essentially blocking conduction. Given...

Hi friends I've a big andu here. Electron revolts around the nucleus in the circular path. Its due to the force between them. Why the electron spins around its own axis?

Electrons paired up in an orbital have anti-parallel spins. One rotates in clockwise direction and the other in anti-clockwise direction in the same orbital. In that case wouldn't the electrons from opposite directions collide each other? Please don't mind if the question seems silly. But thank...

Which of the following require energy? - change the spin of photon - entangle photons - disentangle photons - change the phase of a photon - change the wavelength/frequency of a photon - cause a delay in path of a photon (by each of the various methods) - change the direction of a...

I have become fascinated by Topological Insulators (TI) and wish to learn more about them. I have successfully used a slab calculation to look at one of the prototypical TIs, Bi2Te3 using the LAPW+LO/APW+LO code Wien2K using a 4 quintuple layer slab. I can see the surface states across the...

Hi guys, My question is regarding defining spin operators in the zero field splitting principal axis system. I am currently working on a S = 2 spin system, and know how to define the Sx, Sy, and Sz spin matrices. My question is, how do I rotate them to the zfs-PAS? Some papers I came across...

Homework Statement two identical particles of spin 1/2 that confined in a cubical box of side L. find the energy and wave function (non-interacting between particles) Homework Equations for a cubic boxby and reducing the Schrodinger equation: ψ(x,y,z)=√(8/L3 ) sin((nx πx)/L)sin((ny...

(without using the intuitive yet eronneous idea of "spin" meaning "spinning")

Hi, If we think of an electron's spin as just being a classical kind of a spin, what happens as it speeds up close to the speed of light relative to a laboratory frame of reference? Does the lab frame see the spin of the particle "slow down"?

Suppose an electron crosses worldlines with me such our relative velocities v are a substantial fraction of that of light. Say the electron's spin is in some state \mid\psi\rangle; for example the doublet state. I would like to know, or read references that describe how to calculate, what...

When I was at Uni, in the 60s, we had a brief course on 'Space Physics'. It had a hotch potch of topics in it and one of them was about actually launching satellites. 'In those days', apparently, vehicles were rotated during the launch and this rotation had to be eliminated once they were in...

How is it that only 1 spin up and 1 spin down electron are allowed in an atom even though there is no measurement to collapse the state function?

So my main area of research is molecular biology and biochemistry, but nuclear and particle physics frequently manages to find its way in it and it's always baffling to me. I've been participating in research on bacterial Cytochrome P450 enzymes; they catalyze the oxidation of organic...

Due to diamagnetism in certain substances such as water, does this cause a faster orbital spin due to the change in magnetic dipole moment induced by an external magnet? I'm doing a Science-fair project at the moment and this is eluding me Thank you

Hi, Everybody! Currently, I am reading the book "Lectures on Quantum Field Theory" (by Ashok Das) But I am a bit confusing. Why does Dirac Equation describe spin 1/2 particles? I have already known that Dirac Equation bears some angular momentum structure, but why it just describe spin...

Homework Statement I use Griffiths and see the example for spin 1/2 to derive the eigenspinor of Sx. I just can't seem to follow how he get from there or how he is measuring the probability for a given state. Homework Equations I have correctly derived the...

Please teach me this: We know that orbit angular momentum is the product of coordinate operator vector and momentum operator,so when we reflect the coordinate system the angular momentum is unchanging(axial vector).But I do not understand why spin vector is axial vector. Thank you very much in...

Why does a force used to twist/alter the spin-axis of a spinning wheel increase when the spin motion increases? Why this Gyro effect?

Hi all, In class I've recently been taught the schrodinger equation and about spin(couple weeks apart). My questions are- 1. In laymans terms, what exactly does the S-eqn mean? What I have taken it to be so far, is an equation that determines the probability of the position of an e- in...

We are starting to learn about spin in my introductory quantum mechanics course, and I was wondering if anyone could provide a physical interpretation of an electron's spin. I understand its a form of angular momentum which has nothing to do with the motion of the electron in space, but since an...

It is said that massive stars spin faster than less massive ones and I am always wondering why.Could someone please tell me the reason? Thanks a lot.

Dear physicist, I designed an experiment for my undergraduate students. As we know, for spin operators, the commutation relation is [Si,Sj]=ihSk We also know, if we use two polarizers which are perpendicular each other, there is no light other side after polarizers. Namely apparatus is...

Is spin of electron taken into account when people accelerate electron in LHC?

When you have an ordinary (read: spin zero) particle with a quantum state |ψ>, the corresponding position-space wave function <x|ψ> is an ordinary scalar function of position. How do things work when the particle has spin? In that case its quantum state will live in the tensor product of two...

Some coordination compounds of imino-oximino ligands with cobalt(II) are revealing room temperature magnetic moments around 1.8 to 2.3 B.M. Their visible spectra are revealing broad symmetrical bands around 18 to 20 kK,23to 25 kK the pyridine adduct of one of the complexes also reveals an...

Homework Statement Find spin, parity and isospin of second excited state of {}^{10}B nucleus, if we know that the second excited state (at E_x=1.74 MeV) can intensively be excited with reactions: {}^{7}Li(\alpha,\ n),\ {}^{9}Be(d,\ n),\ {}^{9}Be({}^{3}He,\ d), {}^{11}B(p,\ d), and cannot be...

Homework Statement I have an element: {}^{207}Pb, with Z=82, and A=125, and I need to find spin and parity of it.Homework Equations The angular momentum is determined by the angular momentum of the last nucleon that is odd, in this case it will be one unpaired neutron. Now what confuses me is...

I'm reading about properties of electrons in atoms, and it says an electron's position in an atom can be described by energy level, shape, orientation, and spin roughly speaking: the energy level (n) dictates the radius from the nucleus (probability wise) the shape (l) dictates... the shape...

If I give you a box, completely empty except for one hydrogen atom, could you theoretically measure the spin of its electron to tell me if it is +1/2 or -1/2? If this can be done, how can it be accomplished (at least in theory). Or if the question is complete nonsense, why is that? (Sorry for...

Some friends and I have been having some discussions about why an unfletched arrow will spin right when shot from some bows and left when shot from other bows. We have taken bows and shot a series of different arrows and every arrow out of that bow went in the same direction. So I gues I...

Hi I am working my way through Griffith's Introduction To Quantum Mechanics and I have got to the section on addition of spin angular momenta. I'll copy and paste the bit I'm struggling with, as it's easier than paraphrasing: http://img714.imageshack.us/img714/2783/80183858.png...

I've asked my self this question. How is it that when you spin a bicycle wheel in a vertical plane while holding the axil only on one side that the whole essembly doesn't comes tumbling down. OK, now I know how that is possible. What I'm wondering now is if you take that essembly and rotate it...

modern metal yoyo with ball bearing works totally different with the old. it can spin about 5mins within one throw for some reason. and can it spin about 1min if I throw it horizontally? you may wonder about what is a horizontal throw. then see the video post below. https://vimeo.com/39247415...

Hey Given an anisotropic hamiltonian \mathcal{H} = -\sum_{j,\rho} \left( J_\rho^z s_j^z s_{j+\rho}^z + \frac{J_\rho^{xy}}{2}\left( s_j^+ s_{j+\rho}^- + s_j^- s_{j+\rho}^+ \right)\right) - g\mu_B H\sum_j s_j^z Here \rho is a vector connecting the neighbouring sites. How do I show that the...

Hi all, :shy: Could anyone explain in very simple language, for lower UGrad standard, what spin foams and spin networks are? Thank You. SINCERELY DPA

I was doing some reasearch on electrons, and I found that they have both particle and wave like characteristics. Is this the reason why? because they travel in waves around a nucleus? or am I missing a piece of the puzzel? :smile: Cheers

I think I have a pretty good handle on how scalar field scattering works in QFT, so now I'm trying to wrap my head around spin 1/2 particles, and I'm having a bit of trouble with it. For instance, in N + \phi \rightarrow N + \phi scattering, an application of the Feynman rules leads to an...

Hello , Homework Statement I'm supposed to find restrictions for the spin and parity of the Kaon from the the following decay : K^0 \rightarrow \pi^0 \pi^0 Homework Equations The only thing I know is that \pi^0 spin-parity is 0^- The Attempt at a Solution I said that the spin of the...

Dear forumers, I was thinking about how the Sz operator "couples" (has non zero matrix elements) states with the same expectation values for the projection of spin on the z-axis (duh! α and β are its eigenvectors), and how Sx and Sy couple different states (once again, duh!). I was also...

I have a pyrochlore antiferromagnetic system. In AC magnetic susceptibility measurements, there is a cusp at 4 K whose frequency dependence follows a spin-glass behavior. There is a cusp at around 5 K in magnetic heat capacity, also suggesting a spin-glass transition. But in neutron...

Hello all, Imagine two spin 1/2 particles that are entangled, going towards two stern-gerlach apparatuses, with some relative angle. Now imagine one stern-gerlach device measures the spin of one of the particles as up. What is the chance that the other stern-gerlach device measures the spin...

I already asked this question on physics.stackexchange.com, but did not get the desired response. I am interested in the opinion of your community. Picture an entangled pair of spin 1/2-spin particles with total spin 0. In the diagram, particle 1 of the pair is moving to the left (-y), and...