Spin

[swansont]

By phase-switching, I mean inversion of wave-directionality. I.e. a peak switching to become a trough. It's as if the wave propagates by the energy of the peak transmuting to become its own trough and vice-versa in a linear direction. So it seems as though electron spin is like a non-propagating EM wave oscillation. Then it's as if it propagates as an EM wave by propagating directional-switching of the spin. So the spin would be like actual moving charge that creates current to generate a combined electric-magnetic field. Then that combined field can propagate by oscillating along its axis of rotation. I wonder why electron angular momentum would propagate in that way. It's like it is extremely prone to motion but that its motion is constrained by some internal containment force that requires it to stick to itself whether rotating, propagating, etc. Maybe I'm reading too much into all this, idk.

EM waves propagate perpendicular to the direction of the field oscillation.

[Mike Smith Cosmos]

I didn't see the Ising model until graduate statistical mechanics. What does that mean? It means undergraduate courses (not necessarily just one semester) in general physics, upper-level classes in E&M, thermodynamics, dynamics, modern physics and quantum mechanics, along with calculus and differential equations. At a minimum. Oh, and then a graduate class in dynamics, too. We didn't just show up one day and say "I want to understand this, even if it takes all day"

 

This just in: physics is hard. One does not expect to take up a new sport and quickly be able to play at the professional level. Science is really no different.

 

Things seem to be making gradually a lot more sense with me now I have my little model in my head ( no matter if it is right or wrong ) . I know you are not too keen on these. But I need them as a prop for moving forward.

 

It would seem now to me that the paired electrons in shells , say the first shell, or any other paired electrons in higher shells have a combined angular momentum of 0 ( zero ) , derived from these paired electrons having + 1/2 and - 1/2 spin ( net 0 Zero ). This then is suitable for either a Photon exchange, angular momentum 0 ( zero ) to do some form of exchange and still conserve the angular momentum .

 

Is this a correct interpretation for conservation of angular momentum when moving from Fermion (electron ) to boson (photon ?

 

 

.

Edited March 8, 2011 by Mike Smith Cosmos

[swansont]

It would seem now to me that the paired electrons in shells , say the first shell, or any other paired electrons in higher shells have a combined angular momentum of 0 ( zero ) , derived from these paired electrons having + 1/2 and - 1/2 spin ( net 0 Zero ). This then is suitable for either a Photon exchange, angular momentum 0 ( zero ) to do some form of exchange and still conserve the angular momentum .

 

Is this a correct interpretation for conservation of angular momentum when moving from Fermion (electron ) to boson (photon ?

 

An atom can absorb a photon regardless of the pairing of the electrons, as long as the energy is correct. If the atom is in the S state (no orbital angular momentum), a photon (1 unit of angular momentum) can flip the spin of the electron (going from 1/2 to -1/2 is a change of 1), or promote it to a higher energy state, but only if that state has 1 more unit of angular momentum, i.e. you have to end up in the D state.

[Mike Smith Cosmos]

See http://jayryablon.fi...hat-is-spin.pdf

 

It represents spin as the energy flow of a wave packet of limited size around z-axis. However the spin does not depend on the packet size. Factually it is shown that a vector field has spin 1 and spinor field does 1/2. We knew this without wave packets.

 

BoB Could you contact me , when you have a moment. Thanks Mike Smith Cosmos

[swansont]

BoB Could you contact me , when you have a moment. Thanks Mike Smith Cosmos

 

This is what the "personal conversations" feature is for. Click on the user, and then the "send me a message" button.

[Mike Smith Cosmos]

This is what the "personal conversations" feature is for. Click on the user, and then the "send me a message" button.

 

Sorry, I have not got used to the full features of Science Forum yet.

 

I thought a photon was spin (0 zero) . If not what is spin 0 and spin 2 if a photon has spin 1

Edited March 8, 2011 by swansont
fix qiote

[steevey]

An atom can absorb a photon regardless of the pairing of the electrons, as long as the energy is correct. If the atom is in the S state (no orbital angular momentum), a photon (1 unit of angular momentum) can flip the spin of the electron (going from 1/2 to -1/2 is a change of 1), or promote it to a higher energy state, but only if that state has 1 more unit of angular momentum, i.e. you have to end up in the D state.

 

What exactly happens when a photon hits an electron with the improper amount of energy to push it up exactly to the next possible orbital? Why couldn't it jump two or more orbitals if it absorbed a really high energy photon? What happens if an electron with a really high energy orbital gets struck by a red photon?

[swansont]

What exactly happens when a photon hits an electron with the improper amount of energy to push it up exactly to the next possible orbital? Why couldn't it jump two or more orbitals if it absorbed a really high energy photon? What happens if an electron with a really high energy orbital gets struck by a red photon?

 

If the energy doesn't match an allowed transition, there is no excitation. It can jump an arbitrary number of levels as long as angular momentum is conserved.

[steevey]

If the energy doesn't match an allowed transition, there is no excitation. It can jump an arbitrary number of levels as long as angular momentum is conserved.

 

So what happens to the photon when it gets absorbed by the electron that doesn't jump an electron level?? Does the electron just re-emit it?

[Cap'n Refsmmat]

So what happens to the photon when it gets absorbed by the electron that doesn't jump an electron level??

It doesn't get absorbed by the electron.

[swansont]

I thought a photon was spin (0 zero) . If not what is spin 0 and spin 2 if a photon has spin 1

 

Photons are spin 1. The Higgs is spin 0, and the graviton, should it ever be confirmed, would be spin 2. There are other spin 1 elementary particles, and you can make integral spin composite systems with higher values.

 

http://en.wikipedia.org/wiki/List_of_particles#Bosons

[steevey]

It doesn't get absorbed by the electron.

 

So it just passes right through the electron as if the electron never existed? That doesn't make sense, I mean there waves, how do waves which spread out over technically indefinite probability fields not hit each other when they pass right through the same region of space at the same time? Why wouldn't it just hit a lower level electron if it passed right through outermost electron? Whats going to happen then? The electron would want to go someone, but there's no room in the higher orbitals...

Edited March 9, 2011 by steevey

[granpa]

the atom only absorbs certain frequencies.

all the rest pass right through

 

your radio only absorbs the frequency that it is tuned to.

it absorbs the frequency that resonates.

[Cap'n Refsmmat]

So it just passes right through the electron as if the electron never existed? That doesn't make sense, I mean there waves, how do waves which spread out over technically indefinite probability fields not hit each other when they pass right through the same region of space at the same time? Why wouldn't it just hit a lower level electron if it passed right through outermost electron? Whats going to happen then? The electron would want to go someone, but there's no room in the higher orbitals...

This is why materials can be transparent to certain wavelengths of light. If the electrons cannot accept that amount of energy exactly, then the light is either reflected or transmitted.

[steevey]

This is why materials can be transparent to certain wavelengths of light. If the electrons cannot accept that amount of energy exactly, then the light is either reflected or transmitted.

 

If the light is reflected, then that means the photon hit the electron, but the electron didn't absorb it? And if electron's exist in such improbable states, why are reflected photons so easy to predict perfectly? Also, what exactly do you mean by "transmitted"?

[Cap'n Refsmmat]

If the light is reflected, then that means the photon hit the electron, but the electron didn't absorb it? And if electron's exist in such improbable states, why are reflected photons so easy to predict perfectly? Also, what exactly do you mean by "transmitted"?

 

What improbable states?

 

By "transmitted," I mean the photon passes by without interacting with the electron.

[steevey]

What improbable states?

 

By "transmitted," I mean the photon passes by without interacting with the electron.

 

 

Like an improbability field, which I think you would understand as a "wave function" which essentially maps out a particle's existence. But how does a photon hit an electron without interacting with it? If a photon doesn't have enough energy, the universe automatically sees it coming for every electron and makes the electron move out of the way or something? And what about photon interactions with a nucleus?

 

 

[Cap'n Refsmmat]

Like an improbability field, which I think you would understand as a "wave function" which essentially maps out a particle's existence. But how does a photon hit an electron without interacting with it? If a photon doesn't have enough energy, the universe automatically sees it coming for every electron and makes the electron move out of the way or something? And what about photon interactions with a nucleus?

Stop thinking of the electron and photon like particles that can easily collide; it's just confusing you.

 

Nuclei have different excited states that photons can excite; I'm not certain of the details, as I'm not an atomic physicist.

[granpa]

you might want to study classical physics before trying to get into quantum mechanics.

[Mike Smith Cosmos]

I think its worth remembering that Einstein spent a great deal of time reading peoples ideas and inventions in the swiss patent office. Gazing out the window day after day. Coming up with thought experiments. Riding light beams in his mind , wondering what happened as he approached the speed of light. Being on rocket ships and in elevators. He seemed to come up with some pretty amazing theories. True he later did the maths in conjunction with other mathematicians.

 

Bring back pondering ; observation; postulation; testing by existing theory & experimentation : evaluation; rethinking; argument; discussion: surely that's what we are all about.

[steevey]

Stop thinking of the electron and photon like particles that can easily collide; it's just confusing you.

 

Nuclei have different excited states that photons can excite; I'm not certain of the details, as I'm not an atomic physicist.

 

Never thought they could "easily" collide, but if they occupy the same region of space at the same time, how does the electron know the difference between that fits its energy level and one that doesn't?

[Klaynos]

How does a round peg know it won't fit in a square hole?

[swansont]

Never thought they could "easily" collide, but if they occupy the same region of space at the same time, how does the electron know the difference between that fits its energy level and one that doesn't?

 

First off, they're waves, and second, don't anthropomorphize them. They hate that.

 

Excitation and scattering are not identical phenomenon. The QM view on scattering is that the electron absorbs and re-emits the photon almost immediately. That accounts for the delay in light propagation speed when passing through a medium. The absorbed state is virtual, and no momentum can be transferred to the atom — emission in directions other than straight ahead all destructively interfere. Reflection is similar in that one solution remains, which obeys Snell's law.

 

If there's a real state that matches the photon energy, then the photon disappears and the atom remains in the excited state for some period of time.

[steevey]

First off, they're waves, and second, don't anthropomorphize them. They hate that.

 

Excitation and scattering are not identical phenomenon. The QM view on scattering is that the electron absorbs and re-emits the photon almost immediately. That accounts for the delay in light propagation speed when passing through a medium. The absorbed state is virtual, and no momentum can be transferred to the atom — emission in directions other than straight ahead all destructively interfere. Reflection is similar in that one solution remains, which obeys Snell's law.

 

If there's a real state that matches the photon energy, then the photon disappears and the atom remains in the excited state for some period of time.

 

So if the photon doesn't fit the required energy to move the electron exactly the next or some multiple of the next energy level, then the photon will be absorbed and re-emitted nearly instantly?

[Mike Smith Cosmos]

So if the photon doesn't fit the required energy to move the electron exactly the next or some multiple of the next energy level, then the photon will be absorbed and re-emitted nearly instantly?

 

Steevey, I am going to do a bit of looking for information on the mechanism of electron to photon conversion within the atom. Similarly for photon absorption by the electron in the atom. If I find anything interesting and understandable I will let you know. I think it is all tied up with this angular momentum Spin issue.

Edited March 10, 2011 by Mike Smith Cosmos